Interfacial engineering of Si anodes by confined doping of Co toward high initial coulombic efficiency

A Si/Si-Co multilayer film, with Co confined doping in the silicon anode, was successfully fabricated by alternating magnetron sputtering, achieving both metal doping and surface coating. Operando magnetometry revealed the stability of the Si-Co layers during cycling. The symmetrical Si-Co layers can protect the overall structure of the Si anodes and facilitate electron conduction. Consequently, the resultant Si anode delivers an impressive initial coulombic efficiency of 93.4% with large capacity retention of 85.07% after 100 cycles. In situ magnetometry is used to verify the formation and reveal the stabilizer role of Si/Si-Co multilayer film. The resultant Si/Si-Co anode delivers an initial coulomb efficiency of 93.4% at 1 A g-1 and 85.07% capacity retention after 100 cycles.