Sandwich-like graphene-Bi2S3 hybrid derived from (BiO)2CO3 nanosheets as advanced anode materials for lithium/sodium ion batteries

Abstract

Bismuth sulfides (Bi2S3) are potential electrode materials that have a high theoretical capacity for both lithium and sodium ion batteries. To better utilize the material in practical applications, it is urgent to solve the problem of severe capacity decay caused by low electronic conductivity and large volume change during cycling. Introducing graphene into the system would effectively alleviate these issues on account of the good electrical conductivity, high mechanical flexibility, and large surface area possessed by graphene. However, it is difficult to wrap Bi2S3 with a graphene layer due to the intrinsic hydrophobicity of graphene layers and the strong π-interaction of graphene nanosheets. In this work, sandwich-like graphene-Bi2S3 hybrids (rGO@Bi2S3) are synthesized from two-dimensional (BiO)2CO3 nanosheets (BOC NSs) by electrostatic self-assembly and a subsequent sulfidation process with the assistance of a cationic surfactant. The electrostatic force provides an efficient approach for graphene layers to wrap well around BOC NSs to form a sandwich-like structure that can be retained after the sulfidation process. Benefitting from the merits of high electronic conductivity, robust structure stability, and sufficient space for volume expansion, the as-obtained rGO@Bi2S3 hybrids show both high capacity and cycle stability as the anode of lithium/sodium ion batteries.