EEStor
Encyclopedia
EEStor is a company based in Cedar Park
, Texas
, United States
that claims to have developed a revolutionary new type of capacitor
for electricity storage, which EEStor calls the 'Electrical Energy Storage Unit' (EESU). The claims are described in detail in two of the company's patents, and .
used for electric cars:
claims of the inventors. This has led to the speculation that the claims are false. In January 2007 EEStor stated in a press release "EEStor, Inc. remains on track to begin shipping production 15 kilowatt-hour Electrical Energy Storage Units (EESU) to ZENN Motor Company
in 2007 for use in their electric vehicles." In September 2007, EEStor co-founder Richard Weir told CNET production would begin in the middle of 2008. In August 2008, it was reported he stated "as soon as possible in 2009". ZENN Motor Company
(ZMC) denied there was a delay, just a clarification of the schedule, separating "development" and "commercialization". In March 2008 Zenn stated in a quarterly report a "late 2009" launch was scheduled for an EEStor-enabled EV. In December 2009 Zenn announced that production of the lead acid based ZENN LSV would end April 30, 2010. At that time Zenn did not announce a date for production of an EEstor based car.
In April 2009 EEStor announced third-party certification of permittivity
. The press release did not mention the voltage at which it was tested, so EEStor's uniquely-high energy density claims remain to be demonstrated.
In July 2009 ZENN Motor Company, as a result of the April 2009 permittivity tests, invested an additional $5 million in EEStor, increasing its share of ownership to 10.7%. A Zenn press release indicates they were able to get a 10.7% stake because other EEStor investors did not increase their stake.
As for 2011, nobody has heard anything about the EEStor project, although a statement by the company had been deemed "imminent" for the past three years.
. Many in the industry have expressed skepticism regarding the claims. Jim Miller, vice president of advanced transportation technologies at Maxwell Technologies
and capacitor expert, stated he was skeptical because of current leakage
typically seen at high voltages and because there should be microfractures
from temperature changes. He stated "I'm surprised that Kleiner has put money into it."
(19818) at an unusually high electric field
strength of 350 MV/m, giving 10,000 J/cm³ in the dielectric
. Voltage independence of permittivity was claimed up to 500 V/μm to within 0.25% of low voltage measurements. Variation in permittivity at a single voltage for 10 different components was claimed by measurements in the patent to be less than +/- 0.15%. If true, their capacitors store at least 30 times more energy per volume than (other) cutting-edge methods such as nanotube designs by Dr Schindall at M.I.T., Dr. Ducharme's plastics research, and breakthrough ceramics discussed by Dr. Cann. In such a strong electric field, the permittivity usually decreases due to dielectric saturation, or the dielectric may break down
, causing a short circuit between the capacitor electrodes. Northrop Grumman and BASF have also filed patents with similar theoretical energy density claims. EEStor has the only patent which claims to have actually measured the high energy density in sample components.
The EEStor patents cite a journal article and a Philips Corporation
patent as exact descriptions of its "calcined composition-modified barium titanate powder." The Philips patent describes "doped barium-calcium-zirconium-titanate" (CMBT) and reports a permittivity of up to 33,500 at 1.8 V/μm, but does not report the permittivity at high electric fields such as the 350 V/μm EEStor claims. EEStor coats its 0.64 micrometer (average size) CMBT particles with 10 nm aluminum oxide (6% by volume) and immerses them in 6% PET
plastic by volume, giving 88% CMBT. The patent claims the aluminum oxide coating and PET matrix reduce the net permittivity to 88% of the CMBT permittivity. The Philips patent did not use either aluminum oxide or PET. The dielectric in solution is screen-printed
and dried in 10 μm layers, alternating with 1 μm aluminum plates (used to apply the working 3500 V).
A July 2008 press release states the PET plastic matrix allows for better crystal polarization
and that this "along with other proprietary processing steps provides the potential of a polarization saturation voltage required by EEStor, Inc." The patent states this is done at 180 C with 4000 V.
EEStor's US patent 7033406 mentions aluminum oxide and calcium magnesium aluminosilicate glass as coating
s, although their subsequent US patent 7466536 mentions only aluminum oxide. Nickel was mentioned in the earlier US patent as the electrode but the later patent uses 1 μm aluminum plates as a less expensive alternative. According to the patents, both changes were made possible by selecting the PET matrix because it is pliable enough to fill voids at only 180 C.
In April 2007, ZENN Motor Company, a Canadian electric vehicle manufacturer, invested $2.5 million in EEStor for 3.8% ownership and exclusive rights to distribute their devices for passenger and utility vehicles weighing up to 1,400 kg (excluding capacitor mass), along with other rights. In July 2009, Zenn invested another $5 million for a 10.7% stake. A Zenn press release indicates they were able to get a 10.7% stake because other EEStor investors did not increase their stake. Zenn has received $34 million from the equity markets in the past 3 years, and spent $10.1 million of the proceeds on EEStor ownership and technology rights. In December 2009 Zenn canceled plans for the car but plans to supply the drive train. By April 2010, Zenn had cancelled all production of electric vehicles, leaving ownership of EEStor and their rights to the technology as their focus.
In January 2008, Lockheed-Martin signed an agreement with EEStor for the exclusive rights to integrate and market EESU units in military and homeland security applications. In December 2008, a patent application was filed by Lockheed-Martin that mentions EEStor's patent as a possible electrical energy storage unit.
In September 2008, Light Electric Vehicles Company announced an agreement with EEStor to exclusively provide EEStor's devices for the two and three wheel market.
Cedar Park, Texas
Cedar Park is a city in Travis and Williamson counties in the U.S. state of Texas. According to the 2010 U.S. Census, the population is 48,937. The city is a major suburb of Austin, the center of which is approximately to the southeast, although Austin directly borders Cedar Park at the latter's...
, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
that claims to have developed a revolutionary new type of capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
for electricity storage, which EEStor calls the 'Electrical Energy Storage Unit' (EESU). The claims are described in detail in two of the company's patents, and .
Claimed specifications
The following is how the EESU is claimed to compare to electrochemical batteriesElectrochemistry
Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor , and which involve electron transfer between the electrode and the electrolyte or species in solution.If a chemical reaction is...
used for electric cars:
| Ceramic EESU | NiMH NIMH NIMH or NiMH may refer to:*Nickel-metal hydride battery, a type of rechargeable battery*National Institute of Mental Health, a part of the United States National Institutes of Health... |
Lead-acid(Gel) | Lithium-ion | |
|---|---|---|---|---|
| Weight (kg/lbs) | 135/300 | 780/1716 | 1660/3646 | 340/752 |
| Volume (litres/cubic inches) | 74.5/4541 | 293/17,881 | 705/43,045 | 93.5/5697 |
| Self-discharge rate | 0.02%/30 Days | 5%/30 Days | 1%/30 Days | 1%/30 Days |
| EV Charging time (full) - 100% charge | 3-6 min | >3.0 hr | 3-15 hr | >3.0 hr |
| Life Reduced with deep cycle use | none | very high | high | very high |
| Hazardous Materials | none | yes | yes | yes |
| Temperature vs. effect on energy storage | negligible | high | very high | high |
| Commercially Available | no | yes | yes | yes |
- No degradation from charge/discharge cyclesCharge cycleA charge cycle is the process of charging a rechargeable battery and discharging it as required into a load. The term is typically used to specify a battery's expected life, as the number of charge cycles affects life more than the mere passage of time...
Status and delays
Several delays in production have occurred and there has not been a public demonstration of the uniquely high energy densityEnergy 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...
claims of the inventors. This has led to the speculation that the claims are false. In January 2007 EEStor stated in a press release "EEStor, Inc. remains on track to begin shipping production 15 kilowatt-hour Electrical Energy Storage Units (EESU) to ZENN Motor Company
ZENN Motor Company
ZENN Motor Company , ZENN is an acronym for Zero Emissions No Noise, is a Canadian-based company that previously developed small lead-acid electric vehicles that were suitable for the neighborhood electric vehicle market...
in 2007 for use in their electric vehicles." In September 2007, EEStor co-founder Richard Weir told CNET production would begin in the middle of 2008. In August 2008, it was reported he stated "as soon as possible in 2009". ZENN Motor Company
ZENN Motor Company
ZENN Motor Company , ZENN is an acronym for Zero Emissions No Noise, is a Canadian-based company that previously developed small lead-acid electric vehicles that were suitable for the neighborhood electric vehicle market...
(ZMC) denied there was a delay, just a clarification of the schedule, separating "development" and "commercialization". In March 2008 Zenn stated in a quarterly report a "late 2009" launch was scheduled for an EEStor-enabled EV. In December 2009 Zenn announced that production of the lead acid based ZENN LSV would end April 30, 2010. At that time Zenn did not announce a date for production of an EEstor based car.
In April 2009 EEStor announced third-party certification of permittivity
Permittivity
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how...
. The press release did not mention the voltage at which it was tested, so EEStor's uniquely-high energy density claims remain to be demonstrated.
In July 2009 ZENN Motor Company, as a result of the April 2009 permittivity tests, invested an additional $5 million in EEStor, increasing its share of ownership to 10.7%. A Zenn press release indicates they were able to get a 10.7% stake because other EEStor investors did not increase their stake.
As for 2011, nobody has heard anything about the EEStor project, although a statement by the company had been deemed "imminent" for the past three years.
Skepticism from experts
EEStor's claims for the EESU exceed the energy storage capacity of any capacitor currently sold by orders of magnitudeOrder of magnitude
An order of magnitude is the class of scale or magnitude of any amount, where each class contains values of a fixed ratio to the class preceding it. In its most common usage, the amount being scaled is 10 and the scale is the exponent being applied to this amount...
. Many in the industry have expressed skepticism regarding the claims. Jim Miller, vice president of advanced transportation technologies at Maxwell Technologies
Maxwell Technologies
Maxwell Technologies is a developer and manufacturer of energy storage and power delivery-related products.-History:The company was founded in 1965 as Maxwell Laboratories, originally as a government contractor, providing advanced physics, pulsed power, space effects analysis and other research and...
and capacitor expert, stated he was skeptical because of current leakage
Leakage (electronics)
In electronics, leakage may refer to a gradual loss of energy from a charged capacitor. It is primarily caused by electronic devices attached to the capacitors, such as transistors or diodes, which conduct a small amount of current even when they are turned off...
typically seen at high voltages and because there should be microfractures
Fracture mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture.In...
from temperature changes. He stated "I'm surprised that Kleiner has put money into it."
Patent description and claims
EEStor reports a large relative permittivityPermittivity
In electromagnetism, absolute permittivity is the measure of the resistance that is encountered when forming an electric field in a medium. In other words, permittivity is a measure of how an electric field affects, and is affected by, a dielectric medium. The permittivity of a medium describes how...
(19818) at an unusually high electric field
Electric field
In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...
strength of 350 MV/m, giving 10,000 J/cm³ in the dielectric
Dielectric
A dielectric is an electrical insulator that can be polarized by an applied electric field. When a dielectric is placed in an electric field, electric charges do not flow through the material, as in a conductor, but only slightly shift from their average equilibrium positions causing dielectric...
. Voltage independence of permittivity was claimed up to 500 V/μm to within 0.25% of low voltage measurements. Variation in permittivity at a single voltage for 10 different components was claimed by measurements in the patent to be less than +/- 0.15%. If true, their capacitors store at least 30 times more energy per volume than (other) cutting-edge methods such as nanotube designs by Dr Schindall at M.I.T., Dr. Ducharme's plastics research, and breakthrough ceramics discussed by Dr. Cann. In such a strong electric field, the permittivity usually decreases due to dielectric saturation, or the dielectric may break down
Electrical breakdown
The term electrical breakdown or electric breakdown has several similar but distinctly different meanings. For example, the term can apply to the failure of an electric circuit....
, causing a short circuit between the capacitor electrodes. Northrop Grumman and BASF have also filed patents with similar theoretical energy density claims. EEStor has the only patent which claims to have actually measured the high energy density in sample components.
The EEStor patents cite a journal article and a Philips Corporation
Philips
Koninklijke Philips Electronics N.V. , more commonly known as Philips, is a multinational Dutch electronics company....
patent as exact descriptions of its "calcined composition-modified barium titanate powder." The Philips patent describes "doped barium-calcium-zirconium-titanate" (CMBT) and reports a permittivity of up to 33,500 at 1.8 V/μm, but does not report the permittivity at high electric fields such as the 350 V/μm EEStor claims. EEStor coats its 0.64 micrometer (average size) CMBT particles with 10 nm aluminum oxide (6% by volume) and immerses them in 6% PET
Polyethylene terephthalate
Polyethylene terephthalate , commonly abbreviated PET, PETE, or the obsolete PETP or PET-P, is a thermoplastic polymer resin of the polyester family and is used in synthetic fibers; beverage, food and other liquid containers; thermoforming applications; and engineering resins often in combination...
plastic by volume, giving 88% CMBT. The patent claims the aluminum oxide coating and PET matrix reduce the net permittivity to 88% of the CMBT permittivity. The Philips patent did not use either aluminum oxide or PET. The dielectric in solution is screen-printed
Screen-printing
Screen printing is a printing technique that uses a woven mesh to support an ink-blocking stencil. The attached stencil forms open areas of mesh that transfer ink or other printable materials which can be pressed through the mesh as a sharp-edged image onto a substrate...
and dried in 10 μm layers, alternating with 1 μm aluminum plates (used to apply the working 3500 V).
A July 2008 press release states the PET plastic matrix allows for better crystal polarization
Polarization density
In classical electromagnetism, polarization density is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material. When a dielectric is placed in an external electric field, its molecules gain electric dipole moment and the dielectric is...
and that this "along with other proprietary processing steps provides the potential of a polarization saturation voltage required by EEStor, Inc." The patent states this is done at 180 C with 4000 V.
EEStor's US patent 7033406 mentions aluminum oxide and calcium magnesium aluminosilicate glass as coating
Coating
Coating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance...
s, although their subsequent US patent 7466536 mentions only aluminum oxide. Nickel was mentioned in the earlier US patent as the electrode but the later patent uses 1 μm aluminum plates as a less expensive alternative. According to the patents, both changes were made possible by selecting the PET matrix because it is pliable enough to fill voids at only 180 C.
Partnerships
In July 2005, Kleiner Perkins Caufield & Byers invested $3 million in EEStor.In April 2007, ZENN Motor Company, a Canadian electric vehicle manufacturer, invested $2.5 million in EEStor for 3.8% ownership and exclusive rights to distribute their devices for passenger and utility vehicles weighing up to 1,400 kg (excluding capacitor mass), along with other rights. In July 2009, Zenn invested another $5 million for a 10.7% stake. A Zenn press release indicates they were able to get a 10.7% stake because other EEStor investors did not increase their stake. Zenn has received $34 million from the equity markets in the past 3 years, and spent $10.1 million of the proceeds on EEStor ownership and technology rights. In December 2009 Zenn canceled plans for the car but plans to supply the drive train. By April 2010, Zenn had cancelled all production of electric vehicles, leaving ownership of EEStor and their rights to the technology as their focus.
In January 2008, Lockheed-Martin signed an agreement with EEStor for the exclusive rights to integrate and market EESU units in military and homeland security applications. In December 2008, a patent application was filed by Lockheed-Martin that mentions EEStor's patent as a possible electrical energy storage unit.
In September 2008, Light Electric Vehicles Company announced an agreement with EEStor to exclusively provide EEStor's devices for the two and three wheel market.