Improved electrode performance of mesoporous β-In2S3 microspheres for lithium ion batteries using carbon coated microspheres

Abstract

Mesoporous structure and carbon coating are two important techniques for improving electrode performance for Li ion batteries. The combining of these two techniques in one system offers a new strategy for producing new high-performance electrode materials. Here, we demonstrate a two-step method for preparing carbon coated mesoporous beta-In2S3 microspheres. The mesoporous beta-In2S3 microspheres were synthesized through a solvothermal route, with the assistance of surfactant poly (vinyl pyrrolidone). After treating with glucose in a hydrothermal condition and calcinating under an inert atmosphere, mesoporous beta-In2S3@C microspheres were obtained. Electron microscope and nitrogen absorption studies showed that the sample maintained microsphere morphology and mesoporous structure after carbon treating, but an amorphous carbon layer with a thickness of 8 nm could be found on the surface. Both beta-In2S3 and beta-In2S3@C mesoporous microspheres exhibited remarkable Li storage performance at the initial charge and discharge cycle. Compared with reported beta-In2S3 microspheres without porous structure, the mesoporous beta-In2S3 microspheres showed limited improvement on electrode performance. Furthermore, the carbon coating greatly improved the Li intercalation-deintercalation cycling behaviour. The specific capacity of mesoporous beta-In2S3@C microspheres was almost unchanged after the 5th cycle and was more than three times higher than that of mesoporous beta-In2S3 microspheres after 50 cycles. We suggested that the mesoporous structure and carbon coating together exhibited a better buffering effect for compensating volume changes and enhancing the reversibility of electrode reactions.