Molten salt batteries or liquid sodium battery are a class of primary cell

Primary cell

A primary cell is any kind of battery in which the electrochemical reaction is not reversible, rendering the cell non-rechargeable. A common example of a primary cell is the disposable battery. Unlike a secondary cell, the reaction cannot be reversed by running a current into the cell; the chemical...

 and secondary cell high-temperature electric battery that use molten salt

Molten salt

Molten salt refers to a salt that is in the liquid phase that is normally a solid at standard temperature and pressure . A salt which is normally liquid at STP is usually called a room temperature ionic liquid, although technically molten salts are a class of ionic liquids.-Uses:Molten salts have...

s as an 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....

. They offer both a higher energy density through the proper selection of reactant pairs as well as a higher power density by means of a high-conductivity molten salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 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....

. They are used in services where high energy density

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...

 and high power density

Power density

Power density is the amount of power per unit volume....

 are required. These features make rechargeable molten salt batteries a preferred energy storage to balance out environment-dependent power plants (solar, wind, etc.), and a promising technology for powering 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...

s.