Nitrification protection of Si monocrystal nanoparticles into the graphene matrix as the high-performance anode material for lithium-ion batteries

Silicon is one of ideal anode materials for next-generation lithium ion batteries (LIBs). However, it suffers from a huge volume variation in lithiation/delithiation cycling, and its low conductivity also greatly baffles its far-ranging applications. In this work, novel core-shell structural nanoparticles (NPs), with ceramic Si3N4 shell coated monocrystal Si core, are successfully fabricated through isochronous nitrification within the in situ high-temperature arc plasma. The conductive graphene matrix is introduced into the (Si@Si3N4)/graphene (Gr) nanocomposites (NCs) by a spray-drying process and subsequent thermal treatment. It is indicated that the Si3N4 coating is favorable to the formation of an ionically conductive Li3N phase contained in SEI films, which protects the Si core from breakage and pulverization during cycling. Combination of the graphene matrix can lead to significant enhancement of the electrical conductivity, thus the electrode exhibits superior electrochemical activities, cycling stability and rate capability. The (Si@Si3N4)/Gr NCs are verified to own great potential as the high-performance anode material for LIBs.