In-situ migration of Ni induced crystallization to boost the initial coulombic efficiency of nano Si anode for lithium ion batteries

Silicon (Si) has attracted enormous attention as next-generation anode material for lithium-ion batteries (LIBs) because of its ultra-high capacity. However, the practical application of Si is limited by its low initial coulombic efficiency (ICE) and unstable cycle performance. Here, a Ni-doped highly crystalline porous Si (Ni–CPSi) was prepared through facile magnesiothermic reduction and acid treatment. The enhanced crystallinity of Si effectively decreases the structural defects and suppresses the adverse side reactions. With moderate surface area and porous structure, the side reactions and volumetric expansion of Si during cycling are mitigated. Ni doping in Si crystal lattice further contributes to the enhancement of overall conductivity. As a result, the synthesized Ni–CPSi delivers a high ICE of 83.59%, and a superb rate capability of 682.8 mAh g−1 at 8.4 A g−1. In addition, Ni–CPSi anode achieves ultralong cycle life of 904.5 mAh g−1 at 4.2 A g−1 after 1000 cycles.