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 SnO2/C composite materials is not explored. Sn/SnO2/C composite materials are developed as sulfur carriers in Li-S batteries in our work. In addition, the cycling stability mechanism of Sn/SnO2/C/S composite electrodes is also elucidated. Results show that introduced Sn/SnO2/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/SnO2/C/S composite electrodes is 80 wt % (2 mg-1·cm-2). The introduction of Sn into Sn/SnO2/C/S composite electrodes plays three roles. The first role is to enhance the structural stability of SnO2. 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/SnO2/C/S composite electrodes are beneficial for inhibiting the dissolution of polysulfides in electrolytes after long cycles.