Ni doping carbon skin on SiOx surface to promote the formation of graphitic-N and graphite microcrystals for stable Li storage

Carbon coating is an effective way to solve the structural disintegration problem associated with silicon-based anodes. Although N-doped carbon can increase the number of lithium storage active sites and promote local charge transfer, the decrease of order degree often leads to the decline of electronic conductivity and structural stability during long-term cycling. In this paper, the formation of graphitic N-doped active sites and graphite microcrystals are promoted by the introduction of nickel composites, which effectively improve the conductivity of the carbon skin and the uniform distribution of charge transfer on the carbon skin. Particularly, the order degree of the carbon layer further improves the stability of electrode/electrolyte interfaces. The sample with a suitable amount of Ni sources shows a satisfactory electrochemical performance among samples with different amounts of nickel source introduced. Specifically, the specific capacity of 667.1 mAh g−1 can be maintained after 2000 cycles at 0.5 A g−1, and the capacity retention ratio is up to 77.6%. This work provides effective guidance for the structural design of N-doped carbon coating to optimize the electrochemical properties of SiOx/C composites.