Sumitomo Electric Industries Ltd., in partnership with Kyoto University, has developed a lower temperature molten-salt rechargeable battery that promises to cost only about 10% as much as lithium ion batteries. Sumitomo intends to commercialize the battery around 2015 and market it as an alternative to lithium-ion batteries used in automobiles and homes.
The new 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 Y20,000 per kilowatt-hour–about 10% as much as domestic lithium ion batteries and one-fifth as much as Chinese products.
But unlike a room-temperature lithium ion battery, the new battery must be kept at 80 C to output power. So for the time being, Sumitomo Electric envisions it being used in applications where it is operating continuously, such as homes and electric buses. The company and the university have applied to have the battery patented.
Molten-salt batteries use highly conductive molten salts as an electrolyte, and can offer high energy and power densities. The ZEBRA battery is an example of a molten salt battery. A drawback to the general class of molten salt batteries has been high operating temperatures.