[DaoVeles]

With a lot of new chemistry the risk of fire is greatly reduced. It seems to be an issue mostly with lithium based systems. Things like Iron or sodium based are much safer, energy density is also lower because of this but it is a reasonable trade off. Also tend to have much greater life time charge cycles. Potential to go tens of thousands of cycles rather than just a thousand or so.

[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/