Good Cycling Stabilities of Sn/SnO₂/C/S Composite Electrodes with Introduced Active Tin Atoms in Li–S Batteries

Abstract

Polysulfides are easily dissolved in the electrolyte of Li−S batteries after long cycles. Sn atom modification electrodes are beneficial for improving cycling stabilities of Li−S batteries. However, the influence of Sn atoms on the structure and electrochemical performance of SnO 2 /C composite materials is not explored. Sn/SnO 2 /C composite materials are developed as sulfur carriers in Li−S batteries in our work. In addition, the cycling stability mechanism of Sn/SnO 2 /C/S composite electrodes is also elucidated. Results show that introduced Sn/SnO 2 /C/S composite electrodes display good cycling stability (420.1 mAh•g −1 at 1C after 1000 cycles) in Li−S batteries. The sulfur load of Sn/ SnO 2 /C/S composite electrodes is 80 wt % (2 mg −1 •cm −2 ). The introduction of Sn into Sn/SnO 2 /C/S composite electrodes plays three roles. The first role is to enhance the structural stability of SnO 2 . The second role is to help adsorb active sulfur ions. The last role is to promote the electron transportation ability during the initial discharging/charging process. Sn/SnO 2 /C/S composite electrodes are beneficial for inhibiting the dissolution of polysulfides in electrolytes after long cycles.