Electric vehicle (EV) batteries must be high energy density batteries with high efficiency, light weight, and long cycle life batteries to support low running cost, long range per charge, and high acceleration. All modern electric vehicles are using Lithium-Ion battery. Sodium-Sulfur (NaS) battery will be a cheaper alternative to Lithium-Ion battery.

Sumitomo Electric Industries Ltd. has developed a rechargeable battery that promises to cost about 10% as much as lithium ion batteries. The company aims to commercialize the molten-salt battery by 2015 and market it as an alternative to lithium ion batteries used in automobiles and homes.

The new Sodium-Sulfur (NaS) battery uses sodium-containing substances melted at a high temperature. The technology has been around for decades, but existing molten-salt batteries require keeping the electrolyte in a liquid state at a temperature higher than 300 C. Sumitomo Electric worked with researchers at Kyoto University to develop a sodium material that melts at 57 C.

Having roughly double the energy density of a typical lithium ion battery, the new battery would let an electric vehicle travel twice as far as a lithium ion battery of the same size. Automakers would be able to reduce the space taken up by batteries in their EVs. Molten-salt batteries also boast high heat and impact resistance and are said to be less susceptible to igniting than lithium ion batteries.

Sodium is cheaper than lithium because it is in abundant supply. The new battery is expected to be priced at about 10% as much as domestic lithium ion batteries.