Graphene confined core-shell Si@Cu nanoparticles as integrated anode with enhanced capacity and high-rate performance for Li-ion batteries

Abstract

To cope with volume expansion, poor silicon conductivity and capacity decay due to solid electrolyte interface rupture, rational design of silicon negative electrode is an effective means to cope with the above challenges. We designed a graphene confined Si@Cu core-shell structure (Si@Cu@rGO) as integrated anode, in which the copper shell on the Si nanosurface enhances the electronic conductivity between the silicon particles and graphene. Meanwhile, the flexibility of the copper shell and graphene help suppress the change of electrode morphology during cycling and keep good contact between electrode material and collector. The graphene cladding not only effectively prevents the aggregation of Si@Cu nanoparticles, but also provides enough space for the expansion of silicon during lithiation, while the three-dimensional redox graphene layer builds a conductive structure that accelerates the reaction kinetics of the cell. Thanks to this design, Si@Cu@rGO has a satisfactory electrochemical performance. After 70 cycles in the rate performance test, the specific capacity of Si@Cu@rGO reached 2243.1 mAh g−1.