High specific capacity retention of graphene/silicon nanosized sandwich structure fabricated by continuous electron beam evaporation as anode for lithium-ion batteries

Abstract

A graphene/silicon (Si) multilayer sandwich structures are fabricated using electron beam (EB) deposition without air exposure. The graphene and Si thin films are formed on Cu current correctors through a continuous process in high-vacuum EB chamber. Synthesized graphene should be suggested to the stacked multiple layer from Raman analysis. The fabricated multilayer films are used as anodes. In the beginning, the half-cell, which used a seven-layer of each thickness 50-nm graphene and Si film, exhibits good specific capacity retention over 1000mAhg−1 after 30 charge/discharge cycles. The capacity value changed with the number of graphene and Si layers. In this study, the number of layers that exhibited optimal properties is seven. Morphological investigation showed a fine layer-by-layer structure. The relationship between different thicknesses of graphene and Si is investigated at 7L. A 100-nm thickness exhibited optimal properties. Finally, the optimal 7L and 100-nm thick graphene/Si exhibited high discharge capacitance >1600mAhg−1 at a current density of 100mAg−1 after 30 cycles. Initial coulombic and reversible efficiencies exceed 84%. The capacity retention (30th/1st discharge value) at 100nm and 7L exceeds 90%. Finally, the soft package battery is assembled by combining the fabricated graphene and Si electrode as anode, LiCoO2 as cathode, separator and liquid electrolyte. It can be used for commercial light-emitting diode (LED) lighting even under bending status.