Optimizing the Operation Strategy of the Solid-Conversion Sulfur Cathode for Achieving High Total Capacity Contribution Throughout the Lifespan

A solid-solid sulfur conversion reaction caused by the cathode electrolyte interface (CEI) can effectively prevent the dissolution of lithium polysulfides and theoretically improve the cycle stability of lithium-sulfur (Li-S) batteries. However, since the volume of the reduction product (Li 2 S) exceeds the maximal volume of the host, the as-formed CEI can be destroyed and significantly shorten the cycle life. In this study, we report a simple capacity control strategy to obtain a stable CEI which can greatly increase the total capacity of Li-S batteries throughout whole lifespan. Adjusting the discharging condition leads to a prolonged cycle life over 950 cycles and achieves a remarkable total capacity of 289 Ah g −1 based on sulfur during the whole lifetime of the Li-S cell. Meanwhile, it is also found that the cycle life is depended to a great extent on the lithium anode. This discharging strategy and understanding the solid phase sulfur conversion under the CEI mechanism can advance progress in the development of Li-S batteries.