Preparation of Graphene/Si/C Composite Nanolayer Electrodes by Magnetron Sputtering and Study on Lithium Storage Properties

A Si layer with a thickness of 100 nm and a 50 nm C layer were sputtered on copper-based graphene by magnetron sputtering to form a Graphene/Si/C composite nanolayer electrode. The lithium storage performance was studied by the constant current charge-discharge test, cyclic voltammetry test, cycle performance test, and AC impedance test. The results show that the reversible capacity of the Graphene/Si/C thin film electrode has a serious decay in the early cycle, with an average decay of 1.79 mAh/g per cycle within 200 cycles; the decay is relatively gentle in the latter stage, with an average decay of 0.723 mAh/g per cycle after 1000 cycles. By comparing the SEM and EDS before and after cycling, it was found that the film was broken after cycling, resulting in the loss of active substances.