Core-shell structured Si@Ni nanoparticles encapsulated in graphene nanosheet for lithium ion battery anodes with enhanced reversible capacity and cyclic performance

A Si-based alloy as the negative electrodes of the Lithium-ion batteries (LIBs) possesses the advantages of high discharge capacity and better safety, but low electronic conductivity and poor property limit Si-based anode materials to commercialize for the LIBs. In this article, in order to solve the problems of poor conductivity and cycling instability, core-shell structured Si/Ni nanoparticles encapsulated in graphene nanosheet (Si@Ni-NP@GNS) has been proposed to enhance the electronic conductivity and cycling stability. The nanocomposite was characterized by using the measures of X-ray diffraction and transmission electron microscopy. The Si nano-particles as centre of sphere were coated with interconnected GNS and nickel-plated layer. The electrochemical performance was tested by cyclic voltammetry and galvanostatic charge-discharge tests. The nanocomposite behaves excellent specific capacity, outstanding cycle stability and perfect rate capability, the results show a reversible charge capacity of 2005 mA h g−1 after 50 cycles, which are superior to those of Si@GNS anode and Si@Ni-NP anode. We can be sure that the enhanced electrochemical performance is due to the core-shell structure, which interconnected GNS and nickel-plated layer act as buffer compound to avoid the excessive volume expansion and the electrode pulverization.