Caterpillar started a research project to reduce warranty claims on their starter batteries, which did not last long in the cold. Their team eventually realized they could replace the lead plates with a graphite foam. This gave their batteries the energy density of NiMH, for the cost of lead. They spun off the venture into Firefly Energy [1]. This company was tooling up for release, then the 2008 financial crisis hit. Eventually an Indian company bought the IP. I don&#x27;t know if they are working towards commercialization or not...<p>tl&#x2F;dr: a better battery (probably) already exists, but is not fancy enough to get attention.<p><a href="http:&#x2F;&#x2F;fireflyenergy.com" rel="nofollow">http:&#x2F;&#x2F;fireflyenergy.com</a>