And it is looking good. Double the range within 2-4 years. Sounds great !!
A bit old news. There are other threads about this same battery tech. Saying "400Wh/kg" is a bit misleading because it drops very rapidly at first, looks like 70% after just few cycles, but then it steadies out. So in reality that is more like 280-300Wh/kg, which is not that huge improvement.
What they did improve (assuming it isn't just smoke and mirrors) is price. They claim to be able to manufacture those at $125/kWh, which is cheap. Very cheap even if you increase that by that same margin: ~$180/kWh. That would make Tesla Model S 85kWh battery cost just about $15k (+ assembly + cooling systems + wiring & connectors etc.).
Here is the original thread: