Alphabet’s company X works on project “Malta”, a low-cost energy storage solution using salt and antifreeze.
▻https://9to5google.com/2017/07/31/alphabet-x-malta-clean-energy-storage
Malta’s solution is to contain just captured electricity as thermal energy. The work behind it comes from Nobel prize-winning Stanford physics professor Robert Laughlin who created as “theoretical system that stores electricity as heat (in high temperature molten salt) and cold (in a low temperature liquid similar to the antifreeze you have in your car).”
▻https://www.bloomberg.com/news/articles/2017-07-31/alphabet-wants-to-fix-renewable-energy-s-storage-problem-with-salt