AMPRIUS

Company announced Li-Ion batteries with a silicon anode and 500 Wh/kg

Company Amprius of Fremont, California has announced a new version of its silicon batteries. This new generation has a silicon anode and thus enables the achievement of significantly higher energy densities than is usual today. Most of the Li-Ion available today is somewhere around 160-300 Wh/kg, depending on the mixture, and NIO electric cars with a density of 360 Wh/kg should start to be sold in these months. In terms of volume densities, today we are somewhere around 700-800 Wh/l of the best cells commonly available, although prototypes with a density of around 1000 Wh/l have already been announced. But Amprius goes much further. Its new generation of articles should reach more than 500 Wh/kg a 1300 Wh/l.

Is it just a dream that is far from being realized? Maybe, but it doesn’t look like much. These batteries were independently tested in the Mobile Power Solution laboratories, where 504 Wh/kg and 1321 Wh/l were measured at a temperature of 25 °C. It doesn’t have to mean much either, because one thing is a prototype test and another is real deployment. However, the company already supplies similar cells for stratospheric deployment, which have a density of 450 Wh/kg and 1150 Wh/l at a temperature of 23 °C. They are optimized for a wide range of working temperatures from -30 °C to +55 °C and can handle charging up to 10C. In practice, they should charge 80% capacity in less than 6 minutes. The new generation increases these highly above-average densities by another 12-15%. Although deployment at the edge of space is essential, the company would like to gradually extend these cells to the field of electric air and eventually also land transport (i.e. in electric cars).

If we do the math, such a 100kWh battery could weigh just under 200 kg in cells and have a volume of over 75 liters. The entire battery, i.e. including the package, its control, cooling and other things, would understandably be a bit heavier and larger, but even so, electric cars could already be similarly heavy, if not in some cases lighter, than cars with internal combustion engines ( e.g. compared to diesel cars, especially when it comes to four-wheelers and an automatic transmission, you can expect a lower weight, but gasoline cars with a manual and single-axle drive probably won’t even beat this). Prototypes of cells with 500 Wh/kg should be shipped to selected customers later this year.

In terms of safety, 390 Wh/kg cells have recently been tested to MIL-PRF-32383 (Military Performance Specification) section 4.7.4.4 and withstand a nail puncture with only a slight increase in internal temperature. The US Army has already ordered 30 accumulators with these cells. Future customers include the Advanced Battery Consortium (car companies Ford, GM, Stellantis), which invested in a company to develop cheap cells for electric cars, the company also has a contract with FLIR for batteries for drones, and BAE has a contract to develop batteries for electric aircraft. The company announced plans to build a new factory in Brighton, Colorado. In the first phase, it will have a production capacity of 5 GWh, later it should rise to 10 GWh per year.

by Milan Šurkala