阴极
砜
电解质
溶解
化学
催化作用
无机化学
硫黄
氧化还原
多硫化物
化学工程
材料科学
电极
有机化学
物理化学
工程类
作者
Pengcheng Shi,Xin Liang,Kun Xu,Yi Sun,Sheng Cheng,Chunhua Chen,Hongfa Xiang
标识
DOI:10.1016/j.cej.2020.125608
摘要
Li2S is highly desired for high energy-density lithium sulfur batteries since it allows to be matched with Li metal-free anodes and alleviates the volume expansion of S cathode. However, Li+ extraction from Li2S usually suffers from a huge voltage barrier due to its poor electron conductivity and sluggish Li+ ion diffusion during activation. In this work, trace sulfone-assisted-NH4I is adopted as an electrolyte additive with synergistic dissolution and catalysis effects to alleviate the voltage barrier of Li2S. On one hand, the intercalation between sulfone-NH4+ and Li2S turns solid Li2S into liquid phase, which significantly speeding up the transport of electrons and Li+ ions during activation. On the other hand, I− works as a redox mediator, which further facilitates the oxidation of Li2S to polysulfides. By taking the advantages of synergistic dissolution and catalysis effects from sulfone-NH4+ and I−, the Li2S cathode can be activated at ~3.0 V with a very flat plateau. Finally, the Li2S cathode cycled in the electrolyte with optimized 0.5% sulfone-assisted-NH4I additive shows a high initial discharge capacity of 1160 mAh g−1 at 0.05C, along with enhanced cycling performances and rate capabilities.
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