Lithium ion battery
Encyclopedia
A lithium-ion battery (sometimes Li-ion battery or LIB) is a family of rechargeable battery
types in which lithium
ions move from the negative electrode
to the positive electrode during discharge, and back when charging. Chemistry, performance, cost, and safety characteristics vary across LIB types. Unlike lithium primary batteries (which are disposable), lithium-ion electrochemical cell
s use an intercalated
lithium compound as the electrode material instead of metallic lithium.
Lithium-ion batteries are common in consumer electronics
. They are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities
, no memory effect
, and a slow loss of charge when not in use. Beyond consumer electronics, LIBs are also growing in popularity for military, electric vehicle
, and aerospace
applications. Research is yielding a stream of improvements to traditional LIB technology, focusing on energy density, durability, cost, and intrinsic safety
.
electrolyte
and separator diaphragm.
During charging, an external electrical power source (the charging circuit) applies a higher voltage (but of the same polarity) than that produced by the battery, forcing the current to pass in the reverse direction. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation
.
, cathode
, and electrolyte
. The anode of a conventional lithium-ion cell is made from carbon
, the cathode is a metal oxide
, and the electrolyte
is a lithium
salt in an organic
solvent
.
The most commercially popular anode material is graphite
. The cathode is generally one of three materials: a layered oxide
(such as lithium cobalt oxide
), a polyanion
(such as lithium iron phosphate
), or a spinel
(such as lithium manganese
oxide
).
The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate
or diethyl carbonate
containing complexes of lithium ions. These non-aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate , lithium hexafluoroarsenate monohydrate , lithium perchlorate , lithium tetrafluoroborate , and lithium triflate .
Depending on materials choices, the voltage
, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures
using nanotechnology
have been employed to improve performance.
Pure lithium is very reactive. It reacts vigorously with water to form lithium hydroxide
and hydrogen
gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes water from the battery pack.
Lithium ion batteries are more expensive than NiCd batteries but operate over a wider temperature range with higher energy densities, while being smaller and lighter. They are fragile and so need a protective circuit to limit peak voltages.
The lack of case gives pouch cells the highest energy density; however, pouch cells (and prismatic cells) require an external means of containment to prevent expansion when their state-of-charge
(SOC
) level is high.
Lithium batteries were first proposed by M.S. Whittingham
, now at Binghamton University
, while working for Exxon
in the 1970s. Whittingham used titanium(II) sulfide
as the cathode and lithium metal as the anode.
The reversible intercalation in graphite
and intercalation into cathodic oxides was also already discovered in the 1970s by J.O. Besenhard at TU Munich. He also proposed the application as high energy density lithium cells
Primary lithium batteries in which the anode is made from metallic lithium pose safety issues. As a result, lithium-ion batteries were developed in which both anode and cathode are made of a material containing lithium ions.
In 1979, John Goodenough demonstrated a rechargeable cell with high cell voltage in the 4V range using lithium cobalt oxide
(LiCoO2) as the positive electrode and lithium metal as the negative electrode. This innovation provided the positive electrode material which made LIBs possible. LiCoO2 is a stable positive electrode material which acts as a donor of lithium ions, which means that it can be used with a negative electrode material other than lithium metal. By enabling the use of stable and easy-to-handle negative electrode materials, LiCoO2 opened a whole new range of possibilities for novel rechargeable battery systems.
In 1981, Bell Labs
developed a workable graphite anode to provide an alternative to the lithium metal battery.
In 1982, Rachid Yazami
demonstrated the reversible electrochemical intercalation of lithium in graphite. The organic electrolytes available at the time would decompose during charging if used with a graphite negative electrode, preventing the early development of a rechargeable battery which employed the lithium/graphite system. Yazami used a solid electrolyte to demonstrate that lithium could be reversibly intercalated in graphite through an electrochemical mechanism.
In 1983, Dr. Michael Thackeray, Goodenough, and coworkers identified manganese
spinel
as a cathode material. Spinel showed great promise, given its low-cost, good electronic and lithium ion conductivity
, and three-dimensional structure, which gives it good structural stability. Although pure manganese spinel fades with cycling, this can be overcome with chemical modification of the material. Manganese spinel is currently used in commercial cells.
In 1985, Akira Yoshino
assembled a prototype cell using carbonaceous material into which lithium ions could be inserted as the anode, and as the cathode lithium cobalt oxide (LiCoO2), which is stable in air. By using an anode material without metallic lithium, safety was dramatically improved over batteries which used lithium metal. The use of lithium cobalt oxide (LiCoO2) enabled industrial-scale production to be achieved easily.
This was the birth of the current lithium-ion battery.
In 1991, Sony
and Asahi Kasei
released the first commercial lithium-ion battery.
In 1989, Goodenough and Arumugam Manthiram of the University of Texas at Austin
showed that cathodes containing polyanions, e.g., sulfate
s, produce higher voltages than oxides due to the inductive
effect of the polyanion.
In 1996, Goodenough, Akshaya Padhi and coworkers identified lithium iron phosphate
and other phospho-olivine
s (lithium metal phosphates with the same structure as mineral olivine) as cathode materials.
In 2002, Yet-Ming Chiang and his group at MIT
showed a substantial improvement in the performance of lithium batteries by boosting the material's conductivity by doping
it with aluminum, niobium
and zirconium
. The exact mechanism causing the increase became the subject of widespread debate.
In 2004, Chiang again increased performance by utilizing iron phosphate particles of less than 100 nanometers in diameter. This decreased particle density almost one hundredfold, increased the cathode's surface area and improved capacity and performance. Commercialization led to a rapid growth in the market for higher capacity LIBs, as well as a patent infringement battle between Chiang and Goodenough.
As of 2011, lithium-ion batteries account for 67% of all portable secondary battery sales in Japan.
Both the anode and cathode are materials into which, and from which, lithium can migrate. During insertion (or intercalation
) lithium moves into the electrode. During the reverse process, extraction (or deintercalation), lithium moves back out. When a lithium-based cell is discharging, the lithium is extracted from the anode and inserted into the cathode. When the cell is charging, the reverse occurs.
Useful work can only be extracted if electron
s flow through a closed external circuit. The following equations are in units of moles, making it possible to use the coefficient
.
The positive electrode half-reaction
(with charging being forwards) is:
The negative electrode half-reaction is:
The overall reaction has its limits. Overdischarge supersaturates lithium cobalt oxide
, leading to the production of lithium oxide
, possibly by the following irreversible reaction:
Overcharge up to 5.2 Volts leads to the synthesis of cobalt(IV) oxide, as evidenced by x-ray diffraction
In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co
), in
being oxidized from to during charging, and reduced from to during discharge.
s can electrolyze
, in addition lithium is highly reactive to water, therefore, nonaqueous or aprotic solutions are used.
Liquid
electrolytes in lithium-ion batteries consist of lithium salts, such as
,
or
in an organic
solvent
, such as ethylene carbonate
, dimethyl carbonate
, and diethyl carbonate
. A liquid electrolyte conducts lithium ions, acting as a carrier between the cathode and the anode when a battery passes an electric current through an external circuit. Typical conductivities of liquid electrolyte at room temperature (20 °C (68 °F)) are in the range of 10 mS/cm (1 S/m), increasing by approximately 30–40% at 40 °C (104 °F) and decreasing by a slightly smaller amount at 0 °C (32 °F)
Unfortunately, organic solvents easily decompose on anodes during charging. However, when appropriate organic solvents are used as the electrolyte, the solvent decomposes on initial charging and forms a solid layer called the solid electrolyte interphase (SEI), which is electrically insulating yet provides sufficient ionic conductivity. The interphase prevents decomposition of the electrolyte after the second charge. For example, ethylene carbonate
is decomposed at a relatively high voltage, 0.7 V vs. lithium, and forms a dense and stable interface.
A good solution for the interface instability is the application of a new class of composite electrolytes based on POE (poly(oxyethylene)) developed by Syzdek et al. It can be either solid (high molecular weight) and be applied in dry Li-polymer cells, or liquid (low molecular weight) and be applied in regular Li-ion cells.
Another issue that Li-ion technology is facing is safety. Large scale application of Li cells in Electric Vehicles needs a dramatic decrease in the failure rate. One of the solutions is the novel technology based on reversed-phase composite electrolytes, employing porous ceramic material filled with electrolyte.
anode, metal oxide
cathodes, and lithium
salt in an organic
solvent
for the electrolyte
.
and cell rupture. In extreme cases this can lead to combustion. Deep discharge may short-circuit the cell, in which case recharging would be unsafe. To reduce these risks, Lithium-ion battery packs contain fail-safe circuitry that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell. When stored for long periods the small current draw of the protection circuitry itself may drain the battery below its shut down voltage; normal chargers are then ineffective. Many types of lithium-ion cell cannot be charged safely below 0°C.
Other safety features are required in each cell:
These devices occupy useful space inside the cells, add additional points of failure and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion.
These safety features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.
Because lithium-ion batteries can have a variety of cathode and anode materials, the energy density and voltage vary accordingly.
Lithium-ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal open-circuit voltage
of 3.2 V
and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide cathode with graphite anodes have a 3.7 V nominal voltage with a 4.2 V max charge. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. Some lithium-ion varieties can reach 90% in as little as 10 minutes.
Stage 1: CC: Apply charging current to the battery, until the voltage limit per cell is reached.
Stage 2: Balance: Reduce the charging current (or cycle the charging on and off to reduce the average current) while the State Of Charge
of individual cells is balanced by a balancing circuit, until the battery is balanced.
Stage 3: CV: Apply a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines asymptotically towards 0, until the current is below a set threshold
to prevent operation outside each cell's safe operating area (over-charge, under-charge, safe temperature range) and to balance cells to eliminate SOC
mismatches, significantly improving battery efficiency and increasing overall capacity. As the number of cells and load currents increase, the potential for mismatch also increases. There are two kinds of mismatch in the pack: state-of-charge (SOC) and capacity/energy ("C/E") mismatch. Though SOC is more common, each problem limits pack capacity (mA·h) to the capacity of the weakest cell.
a battery will cause the cell to overheat and possibly to catch fire. Adjacent cells may also then heat up and fail, in some cases, causing the entire battery to ignite or rupture. In the event of a fire, the device may emit dense irritating smoke.
Replacing the lithium cobalt oxide
cathode material in lithium-ion batteries with a lithium metal phosphate such as lithium iron phosphate, improves cycle counts, shelf life and safety, but lowers capacity. Currently, these 'safer' lithium-ion batteries are mainly used in electric car
s and other large-capacity battery applications, where safety issues are critical.
Lithium-ion batteries normally contain safety devices to protect the cells from disturbance. However, contaminants inside the cells can defeat these safety devices.
recalled over 46 million batteries at risk of overheating and exploding. One such incident occurred in the Philippines
involving a Nokia N91
, which uses the BL-5C battery.
In December 2006, Dell
recalled approximately 22,000 laptop batteries from the U.S. market. Approximately 10 million Sony batteries used in Dell
, Sony
, Apple, Lenovo/IBM
, Panasonic
, Toshiba
, Hitachi
, Fujitsu
and Sharp
laptops were recalled in 2006. The batteries were found to be susceptible to internal contamination by metal particles. Under some circumstances, these particles could pierce the separator, causing a short-circuit.
In October 2004, Kyocera Wireless recalled approximately 1 million mobile phone batteries to identify counterfeit
s.
ruled that passengers on board commercial aircraft could carry lithium batteries in their checked baggage if the batteries are installed in a device. Types of batteries affected by this rule are those containing lithium, including Li-ion, lithium polymer, and lithium cobalt oxide
chemistries. Lithium-ion batteries containing more than 25 gram (0.881849052627799 oz) equivalent lithium content (ELC) are exempt from the rule and are forbidden in air travel. This restriction greatly reduces the chances of the batteries short-circuiting and causing a fire.
Additionally, a limited number of replacement batteries may be transported in carry-on luggage. Such batteries must be sealed in their original protective packaging or in individual containers or plastic bags.
Some postal administrations restrict air shipping (including EMS) of lithium and lithium-ion batteries, and products containing these (e.g. laptops, cell phones etc.). Among these countries and regions are Hong Kong
, Australia and Japan
.
Solid-state designs have the potential to deliver three times the energy density of typical 2011 lithium-ion batteries at less than half the cost per kilowatt-hour. This approach eliminates binders, separators, and liquid electrolytes. By eliminating these,
"you can get around 95% of the theoretical energy density of the active materials."
Earlier trials of this technology ran into cost barriers, because the semiconductor industry's vacuum deposition technology cost 20–30 times too much. The new process deposits semiconductor-quality films from a solution. The nanostructured films grow directly on a substrate and then sequentially on top of each other. The process allows the firm to "spray-paint a cathode, then a separator/electrolyte, then the anode. It can be cut and stacked in various form factors.
Rechargeable battery
A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...
types in which lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
ions move from the negative electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
to the positive electrode during discharge, and back when charging. Chemistry, performance, cost, and safety characteristics vary across LIB types. Unlike lithium primary batteries (which are disposable), lithium-ion electrochemical cell
Electrochemical cell
An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...
s use an intercalated
Intercalation (chemistry)
In chemistry, intercalation is the reversible inclusion of a molecule between two other molecules . Examples include DNA intercalation and graphite intercalation compounds.- DNA intercalation :...
lithium compound as the electrode material instead of metallic lithium.
Lithium-ion batteries are common in consumer electronics
Consumer electronics
Consumer electronics are electronic equipment intended for everyday use, most often in entertainment, communications and office productivity. Radio broadcasting in the early 20th century brought the first major consumer product, the broadcast receiver...
. They are one of the most popular types of rechargeable battery for portable electronics, with one of the best energy densities
Energy density
Energy density is a term used for the amount of energy stored in a given system or region of space per unit volume. Often only the useful or extractable energy is quantified, which is to say that chemically inaccessible energy such as rest mass energy is ignored...
, no memory effect
Memory effect
Memory effect, also known as battery effect, lazy battery effect or battery memory, is an alleged effect observed in nickel cadmium rechargeable batteries that causes them to hold less charge...
, and a slow loss of charge when not in use. Beyond consumer electronics, LIBs are also growing in popularity for military, electric vehicle
Electric vehicle
An electric vehicle , also referred to as an electric drive vehicle, uses one or more electric motors or traction motors for propulsion...
, and aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
applications. Research is yielding a stream of improvements to traditional LIB technology, focusing on energy density, durability, cost, and intrinsic safety
Intrinsic safety
Intrinsic safety is a protection technique for safe operation of electronic equipment in explosive atmospheres and under irregular operating conditions. The concept was developed for safe operation of process control instrumentation in hazardous areas, particularly North Sea gas platforms...
.
Charge and discharge
During discharge, lithium ions carry the current from the negative to the positive electrode, through the non-aqueousAqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
and separator diaphragm.
During charging, an external electrical power source (the charging circuit) applies a higher voltage (but of the same polarity) than that produced by the battery, forcing the current to pass in the reverse direction. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation
Intercalation (chemistry)
In chemistry, intercalation is the reversible inclusion of a molecule between two other molecules . Examples include DNA intercalation and graphite intercalation compounds.- DNA intercalation :...
.
Construction
The three primary functional components of a lithium-ion battery are the anodeAnode
An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....
, cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...
, and electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
. The anode of a conventional lithium-ion cell is made from carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
, the cathode is a metal oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
, and the electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
is a lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
salt in an organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
.
The most commercially popular anode material is graphite
Graphite
The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...
. The cathode is generally one of three materials: a layered oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
(such as lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
), a polyanion
Polyelectrolyte
Polyelectrolytes are polymers whose repeating units bear an electrolyte group. These groups will dissociate in aqueous solutions , making the polymers charged. Polyelectrolyte properties are thus similar to both electrolytes and polymers , and are sometimes called polysalts. Like salts, their...
(such as lithium iron phosphate
Lithium iron phosphate
Lithium iron phosphate , also known as LFP, is a compound used in lithium iron phosphate batteries . It is targeted for use in power tools and electric vehicles...
), or a spinel
Spinel
Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4. Balas ruby is an old name for a rose-tinted variety.-Spinel group:...
(such as lithium manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
).
The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate
Ethylene carbonate
Ethylene carbonate is an ester of ethylene glycol and carbonic acid. At room temperature ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state Ethylene carbonate is an ester of ethylene glycol and carbonic...
or diethyl carbonate
Diethyl carbonate
Diethyl carbonate is a carbonate ester of carbonic acid and ethanol. At room temperature diethyl carbonate is a clear liquid with a low flash point....
containing complexes of lithium ions. These non-aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate , lithium hexafluoroarsenate monohydrate , lithium perchlorate , lithium tetrafluoroborate , and lithium triflate .
Depending on materials choices, the voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures
Nanoarchitectures for lithium-ion batteries
Efforts in lithium-ion batteries research have been to improve two distinct characteristics: capacity and rate. The capacity of the battery to store energy can be improved through the ability to insert/extract more lithium ions from the electrode...
using nanotechnology
Nanotechnology
Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension sized from 1 to 100 nanometres...
have been employed to improve performance.
Pure lithium is very reactive. It reacts vigorously with water to form lithium hydroxide
Lithium hydroxide
Lithium hydroxide is an inorganic compound with the formula LiOH. It is a white hygroscopic crystalline material. It is soluble in water and slightly soluble in ethanol...
and hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas. Thus, a non-aqueous electrolyte is typically used, and a sealed container rigidly excludes water from the battery pack.
Lithium ion batteries are more expensive than NiCd batteries but operate over a wider temperature range with higher energy densities, while being smaller and lighter. They are fragile and so need a protective circuit to limit peak voltages.
Formats
Li-ion cells are available in various formats, which can generally be divided into four groups:- Small cylindrical (solid body without terminals, such as those used in laptop batteries)
- Large cylindrical (solid body with large threaded terminals)
- Pouch (soft, flat body, such as those used in cell phones)
- Prismatic (semi-hard plastic case with large threaded terminals, often used in vehicles' traction packs)
The lack of case gives pouch cells the highest energy density; however, pouch cells (and prismatic cells) require an external means of containment to prevent expansion when their state-of-charge
State of charge
State of charge is the equivalent of a fuel gauge for the battery pack in a battery electric vehicle , hybrid vehicle , or plug-in hybrid electric vehicle...
(SOC
State of charge
State of charge is the equivalent of a fuel gauge for the battery pack in a battery electric vehicle , hybrid vehicle , or plug-in hybrid electric vehicle...
) level is high.
History
M Stanley Whittingham
M. Stanley Whittingham is an American chemist. He is currently a professor of chemistry and director of both the Institute for Materials Research and the Materials Science and Engineering program at Binghamton University.- Education and career :Whittingham read Chemistry at the University of...
, now at Binghamton University
Binghamton University
Binghamton University, also formally called State University of New York at Binghamton, , is a public research university in the State of New York. The University is one of the four university centers in the State University of New York system...
, while working for Exxon
Exxon
Exxon is a chain of gas stations as well as a brand of motor fuel and related products by ExxonMobil. From 1972 to 1999, Exxon was the corporate name of the company previously known as Standard Oil Company of New Jersey or Jersey Standard....
in the 1970s. Whittingham used titanium(II) sulfide
Titanium(II) sulfide
Titanium sulfide is an inorganic chemical compound of titanium and sulfur.A meteorite, "Yamato 691", contains tiny flecks of this compound, making it a new mineral called Wassonite....
as the cathode and lithium metal as the anode.
The reversible intercalation in graphite
Graphite intercalation compound
Graphite intercalation compounds are complex materials having formula XCy where element or molecule X is inserted between the graphite layers. In this type of compound, the graphite layers remain largely intact and the guest molecules or atoms are located in between...
and intercalation into cathodic oxides was also already discovered in the 1970s by J.O. Besenhard at TU Munich. He also proposed the application as high energy density lithium cells
Primary lithium batteries in which the anode is made from metallic lithium pose safety issues. As a result, lithium-ion batteries were developed in which both anode and cathode are made of a material containing lithium ions.
In 1979, John Goodenough demonstrated a rechargeable cell with high cell voltage in the 4V range using lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
(LiCoO2) as the positive electrode and lithium metal as the negative electrode. This innovation provided the positive electrode material which made LIBs possible. LiCoO2 is a stable positive electrode material which acts as a donor of lithium ions, which means that it can be used with a negative electrode material other than lithium metal. By enabling the use of stable and easy-to-handle negative electrode materials, LiCoO2 opened a whole new range of possibilities for novel rechargeable battery systems.
In 1981, Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
developed a workable graphite anode to provide an alternative to the lithium metal battery.
In 1982, Rachid Yazami
Rachid Yazami
Rachid Yazami is a scientist best known for his research on lithium ion batteries.-Education:Yazami is a 1978 graduate of the Grenoble Institute of Technology, where he also received a Ph. D. degree in 1985.-Battery research:...
demonstrated the reversible electrochemical intercalation of lithium in graphite. The organic electrolytes available at the time would decompose during charging if used with a graphite negative electrode, preventing the early development of a rechargeable battery which employed the lithium/graphite system. Yazami used a solid electrolyte to demonstrate that lithium could be reversibly intercalated in graphite through an electrochemical mechanism.
In 1983, Dr. Michael Thackeray, Goodenough, and coworkers identified manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
spinel
Spinel
Spinel is the magnesium aluminium member of the larger spinel group of minerals. It has the formula MgAl2O4. Balas ruby is an old name for a rose-tinted variety.-Spinel group:...
as a cathode material. Spinel showed great promise, given its low-cost, good electronic and lithium ion conductivity
Fast ion conductor
In solid-state ionics, fast ion conductors, also known as solid electrolytes and superionic conductors, are materials that act as solid state ion conductors and are used primarily in solid oxide fuel cells. As solid electrolytes they conduct due to the movement of ions through voids, or empty...
, and three-dimensional structure, which gives it good structural stability. Although pure manganese spinel fades with cycling, this can be overcome with chemical modification of the material. Manganese spinel is currently used in commercial cells.
In 1985, Akira Yoshino
Akira Yoshino
is a Japanese chemist. Fellow, Asahi Kasei Corporation Inventor of lithium-ion battery used for cellular phone and notebook computer etc.-Education:1970: Kyoto University / Kyoto, Japan B.S. in Engineering...
assembled a prototype cell using carbonaceous material into which lithium ions could be inserted as the anode, and as the cathode lithium cobalt oxide (LiCoO2), which is stable in air. By using an anode material without metallic lithium, safety was dramatically improved over batteries which used lithium metal. The use of lithium cobalt oxide (LiCoO2) enabled industrial-scale production to be achieved easily.
This was the birth of the current lithium-ion battery.
In 1991, Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
and Asahi Kasei
Asahi Kasei
is a Japanese company. The main products are chemicals and materials science. The company has around 25,000 employees and had consolidated sales of ¥ 1.7 trillion in 2008. It was founded in May 1931, using the paid in capital of Nobeoka Ammonia Fiber Co., Ltd, a Nobeoka, Miyazaki based producer of...
released the first commercial lithium-ion battery.
In 1989, Goodenough and Arumugam Manthiram of the University of Texas at Austin
University of Texas at Austin
The University of Texas at Austin is a state research university located in Austin, Texas, USA, and is the flagship institution of the The University of Texas System. Founded in 1883, its campus is located approximately from the Texas State Capitol in Austin...
showed that cathodes containing polyanions, e.g., sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
s, produce higher voltages than oxides due to the inductive
Electromagnetic induction
Electromagnetic induction is the production of an electric current across a conductor moving through a magnetic field. It underlies the operation of generators, transformers, induction motors, electric motors, synchronous motors, and solenoids....
effect of the polyanion.
In 1996, Goodenough, Akshaya Padhi and coworkers identified lithium iron phosphate
Lithium iron phosphate
Lithium iron phosphate , also known as LFP, is a compound used in lithium iron phosphate batteries . It is targeted for use in power tools and electric vehicles...
and other phospho-olivine
Olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
s (lithium metal phosphates with the same structure as mineral olivine) as cathode materials.
In 2002, Yet-Ming Chiang and his group at MIT
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
showed a substantial improvement in the performance of lithium batteries by boosting the material's conductivity by doping
Doping (semiconductor)
In semiconductor production, doping intentionally introduces impurities into an extremely pure semiconductor for the purpose of modulating its electrical properties. The impurities are dependent upon the type of semiconductor. Lightly and moderately doped semiconductors are referred to as extrinsic...
it with aluminum, niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
and zirconium
Zirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
. The exact mechanism causing the increase became the subject of widespread debate.
In 2004, Chiang again increased performance by utilizing iron phosphate particles of less than 100 nanometers in diameter. This decreased particle density almost one hundredfold, increased the cathode's surface area and improved capacity and performance. Commercialization led to a rapid growth in the market for higher capacity LIBs, as well as a patent infringement battle between Chiang and Goodenough.
As of 2011, lithium-ion batteries account for 67% of all portable secondary battery sales in Japan.
Electrochemistry
The three participants in the electrochemical reactions in a lithium-ion battery are the anode, cathode, and electrolyte.Both the anode and cathode are materials into which, and from which, lithium can migrate. During insertion (or intercalation
Graphite intercalation compound
Graphite intercalation compounds are complex materials having formula XCy where element or molecule X is inserted between the graphite layers. In this type of compound, the graphite layers remain largely intact and the guest molecules or atoms are located in between...
) lithium moves into the electrode. During the reverse process, extraction (or deintercalation), lithium moves back out. When a lithium-based cell is discharging, the lithium is extracted from the anode and inserted into the cathode. When the cell is charging, the reverse occurs.
Useful work can only be extracted if electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s flow through a closed external circuit. The following equations are in units of moles, making it possible to use the coefficient
.The positive electrode half-reaction
Half-reaction
A half reaction is either the oxidation or reduction reaction component of a redox reaction. A half reaction is obtained by considering the change in oxidation states of individual substances involved in the redox reaction.-Example:...
(with charging being forwards) is:
The negative electrode half-reaction is:
The overall reaction has its limits. Overdischarge supersaturates lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
, leading to the production of lithium oxide
Lithium oxide
Lithium oxide or lithia is an inorganic chemical compound. Lithium oxide is formed along with small amounts of lithium peroxide when lithium metal is burned in the air and combines with oxygen:Pure can be produced by the thermal decomposition of lithium peroxide, at 450°C-Structure:In the solid...
, possibly by the following irreversible reaction:
Overcharge up to 5.2 Volts leads to the synthesis of cobalt(IV) oxide, as evidenced by x-ray diffraction
In a lithium-ion battery the lithium ions are transported to and from the cathode or anode, with the transition metal, cobalt (Co
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
), in
being oxidized from to during charging, and reduced from to during discharge.Positive electrodes
| Electrode material | Average potential difference | Specific capacity | Specific energy |
|---|---|---|---|
| 3.7 V | 140 mA·h/g | 0.518 kW·h Watt-hour The kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours... /kg |
|
| 4.0 V | 100 mA·h/g | 0.400 kW·h/kg | |
| 3.5 V | 180 mA·h/g | 0.630 kW·h/kg | |
| 3.3 V | 150 mA·h/g | 0.495 kW·h/kg | |
| 3.6 V | 115 mA·h/g | 0.414 kW·h/kg | |
| 3.6 V | 160 mA·h/g | 0.576 kW·h/kg | |
| Li | 4.2 V | 220 mA·h/g | 0.920 kW·h/kg |
Negative electrodes
| Electrode material | Average potential difference | Specific capacity | Specific energy |
|---|---|---|---|
| Graphite | 0.1-0.2 V | 372 mA·h/g | 0.0372-0.0744 kW·h Watt-hour The kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours... /kg |
| Hard Carbon | ? V | ? mA·h/g | ? kW·h/kg |
| Titanate | 1-2 V | 160 mA·h/g | 0.16-0.32 kW·h/kg |
| Si | 0.5-1 V | 4212 mA·h/g | 2.106-4.212 kW·h/kg |
| Ge | 0.7-1.2 V | 1624 mA·h/g | 1.137-1.949 kW·h/kg |
Electrolytes
The cell voltages given in the Electrochemistry section are larger than the potential at which aqueous solutionAqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
s can electrolyze
Electrolysis
In chemistry and manufacturing, electrolysis is a method of using a direct electric current to drive an otherwise non-spontaneous chemical reaction...
, in addition lithium is highly reactive to water, therefore, nonaqueous or aprotic solutions are used.
Liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
electrolytes in lithium-ion batteries consist of lithium salts, such as
Lithium hexafluorophosphate
Lithium hexafluorophosphate is an inorganic compound with the formula LiPF6. This white crystalline powder is used in commercial secondary batteries, an application that exploits its high solubility in nonpolar solvents. Specifically, solutions of lithium hexafluorophosphate in propylene carbonate...
,
Lithium tetrafluoroborate
Lithium tetrafluoroborate is a chemical compound with the formula LiBF4. It can be dissolved in propylene carbonate, dimethoxyethane, and/or gamma-butyrolactone for use as an electrolyte in lithium batteries....
or
Lithium perchlorate
Lithium perchlorate is the inorganic compound with the formula LiClO4. This white or colourless crystalline salt is noteworthy for its high solubility in many solvents. It exists both in anhydrous form and as a trihydrate.-Uses:...
in an organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
, such as ethylene carbonate
Ethylene carbonate
Ethylene carbonate is an ester of ethylene glycol and carbonic acid. At room temperature ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state Ethylene carbonate is an ester of ethylene glycol and carbonic...
, dimethyl carbonate
Dimethyl carbonate
Dimethyl carbonate, often abbreviated DMC, a carbonate ester, is a flammable clear liquid boiling at 90 °C. This compound has found use as a methylating agent and more recently as a VOC exempt solvent in paints and adhesives . There is also interest in using this compound as a fuel oxygenate...
, and diethyl carbonate
Diethyl carbonate
Diethyl carbonate is a carbonate ester of carbonic acid and ethanol. At room temperature diethyl carbonate is a clear liquid with a low flash point....
. A liquid electrolyte conducts lithium ions, acting as a carrier between the cathode and the anode when a battery passes an electric current through an external circuit. Typical conductivities of liquid electrolyte at room temperature (20 °C (68 °F)) are in the range of 10 mS/cm (1 S/m), increasing by approximately 30–40% at 40 °C (104 °F) and decreasing by a slightly smaller amount at 0 °C (32 °F)
Unfortunately, organic solvents easily decompose on anodes during charging. However, when appropriate organic solvents are used as the electrolyte, the solvent decomposes on initial charging and forms a solid layer called the solid electrolyte interphase (SEI), which is electrically insulating yet provides sufficient ionic conductivity. The interphase prevents decomposition of the electrolyte after the second charge. For example, ethylene carbonate
Ethylene carbonate
Ethylene carbonate is an ester of ethylene glycol and carbonic acid. At room temperature ethylene carbonate is a transparent crystalline solid, practically odorless and colorless, and somewhat soluble in water. In the liquid state Ethylene carbonate is an ester of ethylene glycol and carbonic...
is decomposed at a relatively high voltage, 0.7 V vs. lithium, and forms a dense and stable interface.
A good solution for the interface instability is the application of a new class of composite electrolytes based on POE (poly(oxyethylene)) developed by Syzdek et al. It can be either solid (high molecular weight) and be applied in dry Li-polymer cells, or liquid (low molecular weight) and be applied in regular Li-ion cells.
Another issue that Li-ion technology is facing is safety. Large scale application of Li cells in Electric Vehicles needs a dramatic decrease in the failure rate. One of the solutions is the novel technology based on reversed-phase composite electrolytes, employing porous ceramic material filled with electrolyte.
Advantages and disadvantages
Note that both advantages and disadvantages depend on the materials and design that make up the battery. This summary reflects older designs that use carbonCarbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
anode, metal oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
cathodes, and lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
salt in an organic
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
for the electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
.
Advantages
- Wide variety of shapes and sizes efficiently fitting the devices they power.
- Much lighter than other energy-equivalent secondary batteries.
- High open circuit voltage in comparison to aqueous batteries (such as lead acidLead-acid batteryLead–acid batteries, invented in 1859 by French physicist Gaston Planté, are the oldest type of rechargeable battery. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large...
, nickel-metal hydride and nickel-cadmiumNickel-cadmium batteryThe nickel–cadmium battery ' is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes....
). This is beneficial because it increases the amount of power that can be transferred at a lower current. - No memory effectMemory effectMemory effect, also known as battery effect, lazy battery effect or battery memory, is an alleged effect observed in nickel cadmium rechargeable batteries that causes them to hold less charge...
. - Self-dischargeSelf-dischargeSelf-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes...
rate of approximately 5-10% per month, compared to over 30% per month in common nickel metal hydride batteriesNickel metal hydride batteryA nickel–metal hydride cell, abbreviated NiMH, is a type of rechargeable battery similar to the nickel–cadmium cell. The NiMH battery uses a hydrogen-absorbing alloy for the negative electrode instead of cadmium. As in NiCd cells, the positive electrode is nickel oxyhydroxide...
, approximately 1.25% per month for Low Self-Discharge NiMH batteriesLow self-discharge NiMH batteryThe low self-discharge nickel-metal hydride battery was introduced in November 2005. These batteries were developed by Sanyo, who called them "eneloop". Subsequently, other manufacturers also offered LSD NiMH....
and 10% per month in nickel-cadmium batteriesNickel-cadmium batteryThe nickel–cadmium battery ' is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes....
. According to one manufacturer, lithium-ion cells (and, accordingly, "dumb" lithium-ion batteries) do not have any self-dischargeSelf-dischargeSelf-discharge is a phenomenon in batteries in which internal chemical reactions reduce the stored charge of the battery without any connection between the electrodes...
in the usual meaning of this word. What looks like a self-discharge in these batteries is a permanent loss of capacity (see Disadvantages). On the other hand, "smart" lithium-ion batteries do self-discharge, due to the drain of the built-in voltage monitoring circuit. - Components are environmentally safe as there is no free lithium metal.
Cell life
- Charging forms deposits inside the electrolyte that inhibit ion transport. Over time, the cell's capacity diminishes. The increase in internal resistance reduces the cell's ability to deliver current. This problem is more pronounced in high-current applications. The decrease means that older batteries do not charge as much as new ones (charging time required decreases proportionally).
- High charge levels and elevated temperatures (whether from charging or ambient air) hasten capacity loss. Charging heat is caused by the carbon anode (typically replaced with lithium titanateLithium titanateLithium titanate is a compound containing lithium and titanium. It is an off-white powder at room temperature and has the chemical formula Li2TiO3....
which drastically reduces damage from charging, including expansion and other factors).
Internal resistance
- The internal resistanceInternal resistanceA practical electrical power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This resistance is termed the internal resistance of the source. When the power source delivers current, the measured...
of standard (Cobalt) lithium-ion batteries is high compared to both other rechargeable chemistries such as nickel-metal hydride and nickel-cadmium, and LiFePO4 and lithium-polymer cells. Internal resistanceInternal resistanceA practical electrical power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This resistance is termed the internal resistance of the source. When the power source delivers current, the measured...
increases with both cycling and age. Rising internal resistance causes the voltage at the terminals to drop under load, which reduces the maximum current draw. Eventually increasing resistance means that the battery can no longer operate for an adequate period.
- To power larger devices, such as electric cars, connecting many small batteries in a parallel circuit is more effective and efficient than connecting a single large battery.
Safety requirements
If overheated or overcharged, Li-ion batteries may suffer thermal runawayThermal runaway
Thermal runaway refers to a situation where an increase in temperature changes the conditions in a way that causes a further increase in temperature, often leading to a destructive result...
and cell rupture. In extreme cases this can lead to combustion. Deep discharge may short-circuit the cell, in which case recharging would be unsafe. To reduce these risks, Lithium-ion battery packs contain fail-safe circuitry that shuts down the battery when its voltage is outside the safe range of 3–4.2 V per cell. When stored for long periods the small current draw of the protection circuitry itself may drain the battery below its shut down voltage; normal chargers are then ineffective. Many types of lithium-ion cell cannot be charged safely below 0°C.
Other safety features are required in each cell:
- Shut-down separator (for overtemperature)
- Tear-away tab (for internal pressure)
- Vent (pressure relief)
- Thermal interrupt (overcurrent/overcharging)
These devices occupy useful space inside the cells, add additional points of failure and irreversibly disable the cell when activated. They are required because the anode produces heat during use, while the cathode may produce oxygen. These devices and improved electrode designs reduce/eliminate the risk of fire or explosion.
These safety features increase costs compared to nickel metal hydride batteries, which require only a hydrogen/oxygen recombination device (preventing damage due to mild overcharging) and a back-up pressure valve.
Specifications and design
- Specific energy density: 150 to 250 W·hWatt-hourThe kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours...
/kg (540 to 900 kJ/kg) - Volumetric energy density: 250 to 620 W·h/l (900 to 1900 J/cm³)
- Specific power density: 300 to 1500 W/kg (@ 20 seconds and 285 W·h/l)
Because lithium-ion batteries can have a variety of cathode and anode materials, the energy density and voltage vary accordingly.
Lithium-ion batteries with a lithium iron phosphate cathode and graphite anode have a nominal open-circuit voltage
Open-circuit voltage
Open-circuit voltage is the difference of electrical potential between two terminals of a device when there is no external load connected, i.e. the circuit is broken or open. Under these conditions there is no external electric current between the terminals, even though there may be current...
of 3.2 V
Volt
The volt is the SI derived unit for electric potential, electric potential difference, and electromotive force. The volt is named in honor of the Italian physicist Alessandro Volta , who invented the voltaic pile, possibly the first chemical battery.- Definition :A single volt is defined as the...
and a typical charging voltage of 3.6 V. Lithium nickel manganese cobalt (NMC) oxide cathode with graphite anodes have a 3.7 V nominal voltage with a 4.2 V max charge. The charging procedure is performed at constant voltage with current-limiting circuitry (i.e., charging with constant current until a voltage of 4.2 V is reached in the cell and continuing with a constant voltage applied until the current drops close to zero). Typically, the charge is terminated at 3% of the initial charge current. In the past, lithium-ion batteries could not be fast-charged and needed at least two hours to fully charge. Current-generation cells can be fully charged in 45 minutes or less. Some lithium-ion varieties can reach 90% in as little as 10 minutes.
Battery charging procedure
The charging procedures for single Li-ion cells, and complete Li-ion batteries, are slightly different.- A single Li-ion cell is charged in 2 stages:
- CC
- CV
- A Li-ion battery (a set of Li-ion cells in series) is charged in 3 stages:
- CC
- Balance (not required once a battery is balanced)
- CV
Stage 1: CC: Apply charging current to the battery, until the voltage limit per cell is reached.
Stage 2: Balance: Reduce the charging current (or cycle the charging on and off to reduce the average current) while the State Of Charge
State of charge
State of charge is the equivalent of a fuel gauge for the battery pack in a battery electric vehicle , hybrid vehicle , or plug-in hybrid electric vehicle...
of individual cells is balanced by a balancing circuit, until the battery is balanced.
Stage 3: CV: Apply a voltage equal to the maximum cell voltage times the number of cells in series to the battery, as the current gradually declines asymptotically towards 0, until the current is below a set threshold
Variations in materials and construction
The increasing demand for batteries has led vendors and academics to focus on improving the power density, operating temperature, safety, durability, charging time, output power, and cost of LIB solutions.| Area | Technology | Researchers | Target application | Date | Benefit |
|---|---|---|---|---|---|
| Cathode | Manganese spinel (LMO) | Lucky Goldstar Chemical LG Chem LG Chem Ltd. , often referred to as LG Chemical and also known as Lucky GoldStar Chemical, is the largest Korean chemical company and is headquartered in Seoul, South Korea... , NEC NEC , a Japanese multinational IT company, has its headquarters in Minato, Tokyo, Japan. NEC, part of the Sumitomo Group, provides information technology and network solutions to business enterprises, communications services providers and government.... , Samsung Samsung The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea... , Hitachi Hitachi Hitachi is a multinational corporation specializing in high-technology.Hitachi may also refer to:*Hitachi, Ibaraki, Japan*Hitachi province, former province of Japan*Prince Hitachi and Princess Hitachi, members of the Japanese imperial family... , Nissan/AESC |
Hybrid electric vehicle Hybrid electric vehicle A hybrid electric vehicle is a type of hybrid vehicle and electric vehicle which combines a conventional internal combustion engine propulsion system with an electric propulsion system. The presence of the electric powertrain is intended to achieve either better fuel economy than a conventional... , cell phone, laptop Laptop A laptop, also called a notebook, is a personal computer for mobile use. A laptop integrates most of the typical components of a desktop computer, including a display, a keyboard, a pointing device and speakers into a single unit... |
1996 | durability, cost |
| Lithium iron phosphate | University of Texas/Hydro-Québec Hydro-Québec Hydro-Québec is a government-owned public utility established in 1944 by the Government of Quebec. Based in Montreal, the company is in charge of the generation, transmission and distribution of electricity across Quebec.... ,/Phostech Lithium Inc., Valence Technology Valence Technology Valence Technology, Inc. develops and manufactures advanced lithium iron phosphate cathode materials as well as programmable battery modules and trays. Valence's products are used in electric vehicle and Plug-in hybrid electric vehicles such as cars, scooters, motorbikes, commercial vehicles such... , A123Systems A123Systems A123 Systems develops and manufactures advanced lithium-ion batteries and battery systems for the transportation, electric grid and commercial markets. The company has about 2,500 employees globally and is headquartered in Waltham, Massachusetts. Founded in 2001 by Dr. Yet-Ming Chiang, Dr... /MIT |
Segway Personal Transporter, power tools, aviation products, automotive hybrid systems, PHEV conversions | 1996 | moderate density (2 A·h outputs 70 amperes) operating temperature >60 °C (140 °F) | |
| Lithium nickel manganese cobalt (NMC) | Imara Corporation, Nissan Motor | 2008 | density, output, safety | ||
| LMO/NMC | Sony, Sanyo | power, safety (although limited durability) | |||
| Lithium iron fluorophosphate | University of Waterloo University of Waterloo The University of Waterloo is a comprehensive public university in the city of Waterloo, Ontario, Canada. The school was founded in 1957 by Drs. Gerry Hagey and Ira G. Needles, and has since grown to an institution of more than 30,000 students, faculty, and staff... |
2007 | durability, cost (replace Li with Na or Na/Li) | ||
| Lithium air Lithium air battery The lithium–air battery is a class of lithium battery that employs a cathode which relies on oxygen reduction forming a discharge product... |
University of Dayton Research Institute University of Dayton Research Institute University of Dayton Research Institute is a research institute led by the University of Dayton in Dayton, Ohio. In 2004 and 2005, the Research Institute was ranked #2 in the nation in federal and industry-funded materials research by the National Science Foundation... |
automotive | 2009 | density, safety | |
| 5% Vanadium-doped Lithium iron phosphate olivine | Binghamton University Binghamton University Binghamton University, also formally called State University of New York at Binghamton, , is a public research university in the State of New York. The University is one of the four university centers in the State University of New York system... |
2008 | output | ||
| Anode | Lithium-titanate battery Lithium-titanate battery The lithium–titanate battery is a type of rechargeable battery, which has the advantage of being faster to charge than other lithium-ion batteries. Some analysts speculate that lithium–titanate batteries will power electric cars of the future.... (LT) |
Altairnano Altairnano Altair Nanotechnologies is a Reno, Nevada-based research company that develops nanotechnology-based products for energy storage and the life sciences. In particular, the company is known for its "NanoSafe" lithium-ion battery technology that is used in battery-electric vehicles... |
automotive (Phoenix Motorcars Phoenix Motorcars Phoenix MC, Inc. is a privately held Delaware corporation headquartered in Ontario, California, that does business as Phoenix Motorcars. The Company develops full-size, freeway speed electric vehicles... ), electrical grid (PJM Interconnection Regional Transmission Organization control area, United States Department of Defense United States Department of Defense The United States Department of Defense is the U.S... ), bus (Proterra) |
2008 | output, charging time, durability (20 years, 9,000 cycles), safety, operating temperature (-50 C |
| Lithium vanadium oxide | Samsung/Subaru. | automotive | 2007 | density (745Wh/l) | |
| Cobalt-oxide nano wires from genetically modified virus Genetically modified virus A genetically modified virus is a virus that has gone through genetic modification for various biomedical purposes.-General usage:Genetic modification involves the insertion or deletion of genes. When genes are inserted, they usually come from a different species, which is a form of horizontal gene... |
MIT | 2006 | density, thickness | ||
| Three-Dimensional (3D) Porous Particles Composed of Curved Two-Dimensional (2D) Nano-Sized Layers | Georgia Institute of Technology | high energy batteries for electronics and electrical vehicles | 2011 | specific capacity > 2000 mA·h/g, high efficiency, rapid low-cost synthesis | |
| Iron-phosphate nano wires from genetically modified virus | MIT | 2009 | density, thickness | ||
| Silicon/titanium dioxide composite nano wires from genetically modified tobacco virus | University of Maryland | explosive detection sensors, biomimetic structures, water-repellent surfaces, micro/nano scale heat pipes | 2010 | density, low charge time | |
| Porous silicon/carbon nanocomposite spheres | Georgia Institute of Technology | portable electronics, electrical vehicles, electrical grid | 2010 | high stability, high capacity, low charge time | |
| nano-sized wires on stainless steel | Stanford University Stanford University The Leland Stanford Junior University, commonly referred to as Stanford University or Stanford, is a private research university on an campus located near Palo Alto, California. It is situated in the northwestern Santa Clara Valley on the San Francisco Peninsula, approximately northwest of San... |
wireless sensors networks, | 2007 | density (shift from anode- to cathode-limited), durability issue remains (wire cracking) | |
| Metal hydride Hydride In chemistry, a hydride is the anion of hydrogen, H−, or, more commonly, a compound in which one or more hydrogen centres have nucleophilic, reducing, or basic properties. In compounds that are regarded as hydrides, hydrogen is bonded to a more electropositive element or group... s |
Laboratoire de Réactivité et de Chimie des Solides, General Motors | 2008 | density (1480 mA·h/g) | ||
| Silicon Nanotubes (or Silicon Nanospheres) Confined within Rigid Carbon Outer Shells | Georgia Institute of Technology, MSE, NanoTech Yushin's group | stable high energy batteries for cell phones, laptops, netbooks, radios, sensors and electrical vehicles | 2010 | specific capacity 2400 mA·h/g, ultra-high Coulombic Efficiency and outstanding SEI stability | |
| Silicon nano-powder in a conductive polymer binder | Lawrence Berkeley National Laboratory, Environmental Energy Technologies Division | Automotive and Electronics | 2011 | high capacity anodes (1400 mA·h/g) with good cycling characteristics | |
| Electrode | LT/LMO | Ener1 Ener1 Entrepreneur Mike Zoi and Scientist Peter Novak founded Ener1 in 2001 to develop energy storage technology company that develops compact, lithium-ion-powered battery solutions for the transportation, utility grid and industrial electronics markets. Headquartered in New York City, the company has... /Delphi, |
2006 | durability, safety (limited density) | |
| Nanostructure Nanoarchitectures for lithium-ion batteries Efforts in lithium-ion batteries research have been to improve two distinct characteristics: capacity and rate. The capacity of the battery to store energy can be improved through the ability to insert/extract more lithium ions from the electrode... |
Université Paul Sabatier/Université Picardie Jules Verne | 2006 | density |
Prolonging battery pack life
- Depletion below the low-voltage threshold (2.4 to 2.8 V/cell, depending on chemistry) results in a dead battery which does not even appear to charge because the protection circuit (a type of electronic fuse) disables it.
- Lithium-ion batteries should be kept cool; they may be stored in a refrigerator.
- The rate of degradation of Lithium-ion batteries is strongly temperature-dependent; they degrade much faster if stored or used at higher temperatures.
Multicell devices
Li-ion batteries require a battery management systemBattery Management System
A battery management system is any electronic system that manages a rechargeable battery , such as by monitoring its state, calculating secondary data, reporting that data, protecting the battery, controlling its environment, and / or balancing it.-Monitor:A BMS may monitor the state of the...
to prevent operation outside each cell's safe operating area (over-charge, under-charge, safe temperature range) and to balance cells to eliminate SOC
State of charge
State of charge is the equivalent of a fuel gauge for the battery pack in a battery electric vehicle , hybrid vehicle , or plug-in hybrid electric vehicle...
mismatches, significantly improving battery efficiency and increasing overall capacity. As the number of cells and load currents increase, the potential for mismatch also increases. There are two kinds of mismatch in the pack: state-of-charge (SOC) and capacity/energy ("C/E") mismatch. Though SOC is more common, each problem limits pack capacity (mA·h) to the capacity of the weakest cell.
Safety
Lithium-ion batteries can rupture, ignite, or explode when exposed to high temperature. Short-circuitingShort circuit
A short circuit in an electrical circuit that allows a current to travel along an unintended path, often where essentially no electrical impedance is encountered....
a battery will cause the cell to overheat and possibly to catch fire. Adjacent cells may also then heat up and fail, in some cases, causing the entire battery to ignite or rupture. In the event of a fire, the device may emit dense irritating smoke.
Replacing the lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
cathode material in lithium-ion batteries with a lithium metal phosphate such as lithium iron phosphate, improves cycle counts, shelf life and safety, but lowers capacity. Currently, these 'safer' lithium-ion batteries are mainly used in electric car
Electric car
An electric car is an automobile which is propelled by electric motor, using electrical energy stored in batteries or another energy storage device. Electric cars were popular in the late-19th century and early 20th century, until advances in internal combustion engine technology and mass...
s and other large-capacity battery applications, where safety issues are critical.
Lithium-ion batteries normally contain safety devices to protect the cells from disturbance. However, contaminants inside the cells can defeat these safety devices.
Recalls
In March 2007, Lenovo recalled approximately 205,000 batteries at risk of explosion. In August 2007, NokiaNokia
Nokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
recalled over 46 million batteries at risk of overheating and exploding. One such incident occurred in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
involving a Nokia N91
Nokia N91
The Nokia N91 is a mobile phone that was released to the public in April of 2006. It is part of the Nokia Nseries range of mobile phones. At the time of release, it was the most advanced music phone ever launched by nokia. N91 also won the 'Most Innovative Product' award in recognition of its true...
, which uses the BL-5C battery.
In December 2006, Dell
Dell
Dell, Inc. is an American multinational information technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest...
recalled approximately 22,000 laptop batteries from the U.S. market. Approximately 10 million Sony batteries used in Dell
Dell
Dell, Inc. is an American multinational information technology corporation based in 1 Dell Way, Round Rock, Texas, United States, that develops, sells and supports computers and related products and services. Bearing the name of its founder, Michael Dell, the company is one of the largest...
, Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
, Apple, Lenovo/IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
, Panasonic
Panasonic
Panasonic is an international brand name for Japanese electric products manufacturer Panasonic Corporation, which was formerly known as Matsushita Electric Industrial Co., Ltd...
, Toshiba
Toshiba
is a multinational electronics and electrical equipment corporation headquartered in Tokyo, Japan. It is a diversified manufacturer and marketer of electrical products, spanning information & communications equipment and systems, Internet-based solutions and services, electronic components and...
, Hitachi
Hitachi, Ltd.
is a Japanese multinational conglomerate headquartered in Marunouchi 1-chome, Chiyoda, Tokyo, Japan. The company is the parent of the Hitachi Group as part of the larger DKB Group companies...
, Fujitsu
Fujitsu
is a Japanese multinational information technology equipment and services company headquartered in Tokyo, Japan. It is the world's third-largest IT services provider measured by revenues....
and Sharp
Sharp Corporation
is a Japanese multinational corporation that designs and manufactures electronic products. Headquartered in Abeno-ku, Osaka, Japan, Sharp employs more than 55,580 people worldwide as of June 2011. The company was founded in September 1912 and takes its name from one of its founder's first...
laptops were recalled in 2006. The batteries were found to be susceptible to internal contamination by metal particles. Under some circumstances, these particles could pierce the separator, causing a short-circuit.
In October 2004, Kyocera Wireless recalled approximately 1 million mobile phone batteries to identify counterfeit
Counterfeit
To counterfeit means to illegally imitate something. Counterfeit products are often produced with the intent to take advantage of the superior value of the imitated product...
s.
Transport restrictions
In January 2008, the United States Department of TransportationUnited States Department of Transportation
The United States Department of Transportation is a federal Cabinet department of the United States government concerned with transportation. It was established by an act of Congress on October 15, 1966, and began operation on April 1, 1967...
ruled that passengers on board commercial aircraft could carry lithium batteries in their checked baggage if the batteries are installed in a device. Types of batteries affected by this rule are those containing lithium, including Li-ion, lithium polymer, and lithium cobalt oxide
Lithium cobalt oxide
Lithium cobalt oxide is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS: it consists of...
chemistries. Lithium-ion batteries containing more than 25 gram (0.881849052627799 oz) equivalent lithium content (ELC) are exempt from the rule and are forbidden in air travel. This restriction greatly reduces the chances of the batteries short-circuiting and causing a fire.
Additionally, a limited number of replacement batteries may be transported in carry-on luggage. Such batteries must be sealed in their original protective packaging or in individual containers or plastic bags.
Some postal administrations restrict air shipping (including EMS) of lithium and lithium-ion batteries, and products containing these (e.g. laptops, cell phones etc.). Among these countries and regions are Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
, Australia and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
Research
Researchers are working to improve the power density, safety, recharge cycle, cost and other characteristics of these batteries.Solid-state designs have the potential to deliver three times the energy density of typical 2011 lithium-ion batteries at less than half the cost per kilowatt-hour. This approach eliminates binders, separators, and liquid electrolytes. By eliminating these,
"you can get around 95% of the theoretical energy density of the active materials."
Earlier trials of this technology ran into cost barriers, because the semiconductor industry's vacuum deposition technology cost 20–30 times too much. The new process deposits semiconductor-quality films from a solution. The nanostructured films grow directly on a substrate and then sequentially on top of each other. The process allows the firm to "spray-paint a cathode, then a separator/electrolyte, then the anode. It can be cut and stacked in various form factors.
See also
- Potassium-ion batteryPotassium-ion batteryThe potassium-ion battery was first invented by the American/Iranian chemist, Ali Eftekhari, in 2004 as an alternative to lithium-ion batteries. The battery uses Prussian blue as the cathode material for its stability, the prototype could be successfully used for millions of cycles...
- Nanowire batteryNanowire batteryA nanowire battery is a lithium-ion battery invented by a team led by Dr. Yi Cui at Stanford University in 2007. The team's invention consists of a stainless steel anode covered in silicon nanowires, to replace the traditional graphite anode...
External links
- Asahi Kasei Corporation -- Father of the lithium-ion battery
- Argonne opens chapter in battery research -- lithium air. Argonne National Labs. Press release. 14 September 2009.
- Battery and Energy Technologies - Rechargeable Lithium batteries. Electropaedia; Woodbank Communications Ltd. Updated 28 April 2010.
- Stanford's nanowire battery holds 10 times the charge of existing ones. Stanford Report, 18 December 2007. Press release.
- The Lithium Ion Battery. E-Articles.com. (Self-publishing site).
- The Future of Electric Vehicles: Setting the Record Straight on Lithium Availability. Journal of Energy Security, 27 August 2009. Keith Evans.
- http://www.prnewswire.com/news-releases/researchers-from-spheric-technologies-and-arizona-state-university-describe-major-advances-in-the-use-of-microwaves-to-produce-key-lithium-ion-battery-materials-present-papers-at-mst10-conference-october-17-21-105166424.htmlResearchers from Spheric Technologies and Arizona State University Describe Major Advances in the Use of Microwaves to Produce Key Lithium Ion Battery Materials; Present Papers at MS&T'10 Conference, October 17-21]. Spheric Technologies. Press release. October 18, 2010.