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 β-In₂S₃ microspheres. The mesoporous β-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 β-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 β-In₂S₃ and β-In₂S₃@C mesoporous microspheres exhibited remarkable Li storage performance at the initial charge and discharge cycle. Compared with reported β-In₂S₃ microspheres without porous structure, the mesoporous β-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 β-In₂S₃@C microspheres was almost unchanged after the 5th cycle and was more than three times higher than that of mesoporous β-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.