[rootusrootus]

> an issue mostly with lithium based systems. Things like Iron or sodium based are much safer

The iron battery you are thinking of is a lithium battery. It is not the lithium that is a fire risk; lithium ion batteries do not contain metallic lithium. In an LFP battery the phosphate-oxide bond is much more stable and not subject to thermal runaway compared with e.g. cobalt-oxide.

[DaoVeles]

That sounds much better than the dribble I was spouting. Thanks!

[DennisP]

There's also someone building a factory to make iron-air batteries for grid storage. They're way cheaper than lithium or even sodium, with one of the most common materials on the planet, but only about 50% efficient. They're too heavy for vehicles, and have lower power output so aren't much good as peakers, but if you want four days of grid backup like we'd need with a 100% wind/solar grid, they're great.

https://formenergy.com/technology/battery-technology/