Exfoliated-SnS₂ restacked on graphene as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries.

Abstract

Designed as a high-capacity, high-rate, and long-cycle life anode for sodium ion batteries, exfoliated-SnS2 restacked on graphene is prepared by the hydrolysis of lithiated SnS2 followed by a facile hydrothermal method. Structural and morphological characterizations demonstrate that ultrasmall SnS2 nanoplates (with a typical size of 20-50 nm) composed of 2-5 layers are homogeneously decorated on the surface of graphene, while the hybrid structure self-assembles into a three-dimensional (3D) network architecture. The obtained SnS2/graphene nanocomposite delivers a remarkable capacity as high as 650 mA h g(-1) at a current density of 200 mA g(-1). More impressively, the capacity can reach 326 mA h g(-1) even at 4000 mA g(-1) and remains stable at ∼610 mA h g(-1) without fading up to 300 cycles when the rate is brought back to 200 mA g(-1). The excellent electrochemical performance is attributed to the synergetic effects between the ultrasmall SnS2 and the highly conductive graphene network. The unique structure can simultaneously facilitate Na(+) ion diffusion, provide more reaction sites, and suppress aggregation and volume fluctuation of the active materials during prolonged cycling.