Novel design of ultra-fast Si anodes for Li-ion batteries: crystalline Si@amorphous Si encapsulating hard carbon

Nanocrystalline Si (c-Si) dispersed in amorphous Si (a-Si) encapsulating hard carbon (HC) has been synthesized as a new anode material for next generation lithium-ion batteries. An excellent cycle retention of 80% was exhibited for a HC@c-Si@a-Si/LiCoO2 full cell after 160 cycles at 1 C discharge/charge rate.