Lithium ion batteries have been so far the best option for storing energy. Lithium is nevertheless an expensive material and a precious natural resource, whose extraction involves complex chemical processes, often damaging to the environment. Sodium-nickel chloride batteries, on the other hand, promise a cheaper alternative to lithium ion due to recent innovations from the Pacific Northwest National Laboratory.
The PNNL researchers have tweaked the otherwise old sodium-beta alumina batteries to deliver 30% more power at lower temperatures. Until now, sodium-beta batteries had lost territory in front of lithium because their cylindrical shape did not allow efficient discharge rates, and pushed the battery to work at high temperatures, lowering their lifespan and cost-effectiveness.
“This planar sodium battery technology shows potential as an option for integrating more solar and wind power into our electric grid,” said Carl Imhoff, PNNL electricity infrastructure sector manager at the Department of Energy laboratory.
The redesigned sodium-beta batteries do not use the classic cylindrical shape, but the researchers found that a planar design allows them to have a thinner cathode and a larger surface area for a given volume. The ions can flow in a larger area and a shorter pathway, thus reducing the electrical resistance. The usage of a thin layer of solid electrolytes also lowers the resistance.
Both these innovations allow the battery to be operated at lower temperatures and still get 30% more power than the old sodium-beta cylindrical piles.
“Our goal is to get a safer, more affordable battery into the market for energy storage. This development in battery technology gets us one step closer,” said PNNL Scientist Xiaochuan Lu, co-author of the paper published in the October 8 issue of ECS Transactions.