The solid state battery people continue to inch forward to 500Wh/Kg.[1] That's about 2x lithium-ion. There are now a small number of prototype cars on the road with solid state batteries. There's even a Dodge Charger, from Stellantis. But nobody has solved the production cost problem yet. CATL has a summary of their approach.[2]
This is the real win, but it's hard to make it work in production. Eventually it will displace hybrids, but not before 2030.
[1] https://electrek.co/2026/08/20/geely-500-wh-kg-solid-state-b...
[2] https://www.intelligentliving.co/catl-500-whkg-solid-state-b...
China's regulators have recently issued an official definition of "solid state battery".[1] This applies to advertising, and, importantly, to investment fund-raising. Semi solid state batteries, with gels or some liquid, do not qualify. They will officially be called “hybrid solid-liquid battery.”
The test is simple and tough. Heat a cut battery to 120C, and the weight must not decrease by more than 0.5%. Once the standard takes effect, only batteries passing that test can be called "solid state". Nobody has this yet outside of lab samples.
This will help avoid fake solid state battery claims such as the Donut Labs fiasco [2]
[1] https://www.intelligentliving.co/solid-state-battery-standar...
[2] https://www.cnet.com/home/electric-vehicles/donut-lab-solid-...