Silicon Based High Performance EV Batteries

Nanomakers is a French start-up that manufactures at industrial scale four types of nanosilicon for high capacities Li-ion batteries for electric vehicles (EV): pure Si with particles size at 40 and 75 nm carbon-coated Si particles at 40 and 75 nm. Those ultra fine particles are produced with narrow particle size distribution by laser pyrolysis. This process is reproducible, robust and the particles have low oxygen contents. The existing Li-ion technology uses for the anodes graphite with 350 mAh/g capacities. Nanomakers particles enable the manufacturing of high capacities Li-ion batteries anodes: 800 mAh/g along with a good capacity retention along cycling (>100 cycles). For silicon anodes, various formulations are studied but the most promising uses pre-composite in which the silicon is dispersed in a carbon matrix which is then partly decomposed by a thermal treatment. It is processed at a much lower temperature than graphitization processes. This micronic pre-composite can then be used as a high capacity raw material for anodes without changing anode preparation existing processes. The use of carbon-coated particles improves the anode performances during cycling, especially the capacity stability. This presentation compares the results obtained with various preparations and types of particles. The carbon coating has a positive impact on the batteries performances.