Abstract

Practical application of Li-S battery is limited by the fast capacity decay and low coulombic efficiency caused by the shuttling phenomenon. Modification of the battery separator to impart the separator with ionic sieving property is an effective strategy to alleviate the shuttling phenomenon. In this study, perfluorinated sulfonic acid (PFSA) ionomers with different equivalent weight (EW) values are used to modify the commercial polyethylene separator, and the electrochemical performance of these separators is systematically investigated. Our results show that the separator modified using PFSA ionomer with a low EW value of 830 shows optimal battery performance owing to its unique structure of the ionic cluster. The Li-S battery with this modified separator shows an initial discharge capacity of 1352 mAh g⁻¹ and a retained capacity of 931.6 mAh g⁻¹ after cycling 100 times at 0.2 C, which demonstrates the effectiveness of this modification strategy. Furthermore, the correlation between the properties of PFSA ionomers and the electrochemical performance of the modified separator unveiled in this study may provide insight for the rational design of advanced separator for battery applications.

中文翻译：

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高性能锂电池全氟磺酸离子筛修饰隔膜的合理设计

摘要

Li-S电池的实际应用受到穿梭现象引起的快速容量衰减和低库仑效率的限制。电池隔板的改性以赋予隔板离子筛选性能是减轻穿梭现象的有效策略。在这项研究中，使用具有不同当量重量（EW）值的全氟化磺酸（PFSA）离聚物来修饰商用聚乙烯隔膜，并对这些隔膜的电化学性能进行了系统的研究。我们的结果表明，使用具有830的低EW值的PFSA离聚物改性的隔板，由于其具有独特的离子簇结构，因此具有最佳的电池性能。带有改进型隔板的Li-S电池的初始放电容量为1352 mAh g ^-1在0.2 C下循环100次后的保留容量为931.6 mAh g ^-1，这证明了该修饰策略的有效性。此外，本研究中揭示的PFSA离聚物的性能与改性隔膜的电化学性能之间的相关性可能为合理设计用于电池的高级隔膜提供了见识。