Ultrathin Si Nanosheets Dispersed in Graphene Matrix Enable Stable Interface and High Rate Capability of Anode for Lithium-ion Batteries

Owing to the thinness and large lateral size, 2D Si materials exhibit very promising prospects as the high-performance anodes of lithium-ion batteries (LIBs). However, the facile synthesis of ultrathin 2D Si nanosheets (Si-NSs) and their efficient application still remain a great challenge. Herein, the fabrication of ultrathin Si-NSs with the average thickness of <2 nm is demonstrated using a unique etching-reduction protocol. After hybridizing with graphene, the as-prepared Si-NSs@rGO material delivers ultrahigh rate capability (2395.8 mAh g⁻¹ at 0.05 A g⁻¹ and 1727.3 mAh g⁻¹ at 10 A g⁻¹), long cycling lifespan (1000 cycles at 2 A g⁻¹ with a capacity decay rate of 0.05% per cycle) and high average Coulombic efficiency (99.85% during 1000 cycles). The superior performance is attributed to the ultrathinness of Si-NSs that greatly improves the diffusivity and reversibility of Li⁺ ions. This work provides a strategy for fabricating a high-rate-capability anode material to meet the growing demand for high power density LIBs.