Performance Stabilization of Lithium-Sulfur Batteries Containing Sulfolane-based Electrolyte and Microporous Cathode by Controlling Working Voltage Range (Supporting Information)

For lithium-sulfur (Li-S) batteries, high-concentration electrolyte that inhibits the dissolution of Li polysulfide has been widely studied; one such electrolyte contains sulfolane. This study investigates the conditions under which a microporous activated carbon cathode, derived from azurmic acid, operates stably in a sulfolane-based electrolyte. We expected this cathode to maintain a stable capacity in a sulfolane-based electrolyte because its micropores stabilize the S species. However, Li-S batteries containing this cathode and electrolyte exhibit significant capacity decay during cycling. The cutoff voltage during charge-discharge cycling is varied to suppress the capacity decay. At a discharge voltage of 1.4 V or lower, the cycle life of the Li-S batteries is significantly reduced. Conversely, increasing the cutoff voltage during discharge suppresses the capacity decay of Li-S batteries. On the other hand, increasing the upper voltage limit during charging increases the reversible capacity. Thus, the operating voltage range is optimized. This study indicates that the voltage range of Li-S batteries should be carefully determined depending on the type of cathode material and electrolyte.

针对锂硫（Li-S）电池，高浓度电解质抑制锂多硫化物溶解的研究已广泛展开；其中一种电解质含有硫杂环己烷。本研究旨在探讨以硫杂环己烷为基的电解质中，由蓝矾酸制备的微孔活性碳负极稳定工作的条件。我们预期该负极在硫杂环己烷基电解质中能够维持稳定的容量，因其微孔结构能够稳定硫物种。然而，含有此负极和电解质的Li-S电池在循环过程中表现出显著的容量衰减。通过调整充放电循环的截止电压以抑制容量衰减。在放电电压1.4伏或更低时，Li-S电池的循环寿命显著降低。相反，在放电过程中提高截止电压可以抑制Li-S电池的容量衰减。另一方面，在充电过程中提高上限电压可以提高可逆容量。因此，优化了工作电压范围。本研究表明，Li-S电池的电压范围应根据正极材料和电解质类型进行仔细确定。