N-doped graphitic self-encapsulation for high performance silicon anodes in lithium-ion batteries

N-doped sites at CNT and graphene trigger spontaneous encapsulation of Si particles by simple pH control at room temperature. Significantly, N-doped CNT encapsulated Si composite electrode materials show remarkable cycle life and rate performance in battery operations. Superior capacity retention of 79.4% is obtained after 200 cycles and excellent rate capability of 914 mA h g(-1) is observed at a 10 C rate.