Nano Carbon Lead Acid technology pricey but impressive

At $17,000 per battery, they can be cycled 5000 times.  That is 5 times more than regular lead-acid but the price is more than 5 times higher.  But, it's a new technology and prices will surely drop, perhaps dramatically.

https://www.civicsolar.com/support/installer/articles/bridge-nano-carbon-lead-acid