Redflow ZCell batteries
These batteries have been in development for ten years. They are flow batteries, which basically means there is a liquid flowing around inside.
Anyway, there are some important differences between these and lithium ion batteries.
1. The solution is comprised of a liquid that is (or was) used in fire extinguishers. So no fear of them causing fires.
2. There is no loss of capacity over time. a 10KWh battery will still be providing 10KWh of storage in 10 years time.
3. There is no reserve needed, which means you can completely run the battery down. So you actually get to use the full 10KWh.
4. These batteries are relatively small in comparison to other flow batteries. Meaning, you can use them to power your home or office location.
They do cost more than their lithium ion counterparts, but the total cost of ownership is already less and the price is expected to come down a lot over time.
Sounds good to me, if only for the fact that the more diversity and competition in the home storage market, the better.