Design of PVDF-g-PAA Binder Endowing High Sulfur Loading With Enhanced Performance of Lithium-Sulfur Batteries

초록

Lithium-sulfur (Li-S) batteries have received considerable attention as promising candidates for next-generation batteries because of their high theoretical energy density (approximate to 2600 Wh kg(-1)). However, despite their abundant active material and high theoretical capacity, the commercialization of Li-S batteries has been hindered by several difficulties such as the shuttle effect of lithium polysulfides (LiPS). In this study, we designed poly (vinylidene fluoride)-graft-poly (acrylic acid) (PVDF-g-PAA) as a novel binder to realize high sulfur loading electrodes for Li-S batteries. The synthesis conditions of PVDF-g-PAA were controlled based on its chemical structure, mechanical properties, and electrochemical performance. The optimal structure of PVDF-g-PAA exhibited high LiPS adsorption ability compared to that of PVDF, which retained its mechanical properties. Therefore, the unit cell with a high sulfur loading of 5.7 mg cm(-2) fabricated using PVDF-g-PAA yielded a high reversible capacity of 644.1 mAh g(-1) after 100 cycles. Consequently, this study provides a useful approach to improve the cycling performance of Li-S batteries by modifying commercial binders, which demonstrates their practical potential for developing Li-S batteries.

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