“The energy density performance was verified by [test house] Mobile Power Solutions. The results indicate that this cell model provides >504Wh/kg and >1,321Wh/litre at 25°C,” according to Amprius.
This comes from switching from graphite to silicon for the anode – easily said, but not easily done. The problem is that silicon anodes swell greatly as they take in ions, breaking the anode apart.
Amprius solution is a move to silicon nanowires (see images) whose geometry is far less prone to swelling. It claims offer a life of between 200 and 1,200 cycles – at least for early commercial versions of its silicon anode Li-ion cells, which it describes as having capacities in the 360 – 450Wh/kg (up to 1,150Wh/litre) range.
How much these cost is not revealed – the company is currently aiming at high value applications such as the military and aviation – not vehicles or phones, although it said that the “next-generation cells are well positioned to power products in aviation and, eventually, electric vehicles”.
While pilot manufacturing is in California, Amprius recently signed a letter of intent for a facility in Colorado “that initially provides a potential of up to 5GWh manufacturing capacity”.