Loz Blain – 
One of the primary problems with renewable energy, particularly wind and solar, is that power gets generated when the wind or sun is available, rather than when it’s most needed. This problem would more or less disappear if the world could come up with a massive, cheap, long-lasting battery design that could be used to store power at grid-scale levels and feed it back out when required.
Lithium batteries are the current darlings (heh heh) of the electric vehicle and consumer electronics industries, due to their high performance, power density and light weight. But lithium is way too expensive a material for grid-scale storage, and when you’re talking about making batteries for a whole city, size and weight are far less important than making something super cheap, safe and reliable that will last for as long as possible. All the better if it can be made out of common and easily available materials.
Good news, then, from MIT on this front, as a team of researchers has found a cheap, effective and durable way of resurrecting an old battery idea first documented 50 years ago.
The discovery centers around molten salt batteries such as sodium/sulfur or sodium/nickel chloride designs in which electrodes are kept at high temperatures to keep them in a molten state and allow charge to transfer between them.
(For complete article see: https://newatlas.com/mit-molten-salt-battery-membrane/53085/)