Electrocatalytic MOF‐Carbon Bridged Network Accelerates Li+‐Solvents Desolvation for High Li+ Diffusion toward Rapid Sulfur Redox Kinetics
Electrocatalytic MOF‐Carbon Bridged Network Accelerates Li+‐Solvents Desolvation for High Li+ Diffusion toward Rapid Sulfur Redox Kinetics
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DOI：
10.1002/adfm.202212499
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发表时间：
2023-01
影响因子：
19
通讯作者：
Linge Li;Haifeng Tu;Jian Wang;Mingchao Wang;Wanfei Li;Xiang Li;Fangmin Ye;Qinghua Guan
中科院分区：
文献类型：
--
作者：
Linge Li;Haifeng Tu;Jian Wang;Mingchao Wang;Wanfei Li;Xiang Li;Fangmin Ye;Qinghua Guan
锂硫电池以高能量密度著称，但由于锂离子在电极/电解液界面传输的高能垒，穿梭效应和电化学转化动力学缓慢阻碍了锂硫电池的发展。本文通过设计一个碳桥金属-有机骨架(MOF@CC)来催化和模拟Li+-溶剂的分解动力学，旨在实现增加裸Li+的迁移，从而实现硫物种的快速转化动力学。理论模拟和光谱结果表明，桥连的MOF@CC势垒为加速Li+提供了一条特殊的输运通道，得益于聚集的阴阳离子团簇。此外，分子筛中的-NH_2配体与碳壳之间的C-N桥加强了电子交换，从而提高了多硫化物的催化效率，阻碍了多硫化物的聚集和积累。使用MOF@CC改性隔膜，组装的Li/S电池在0.5C时的可逆容量为1063mAhg-1,100次循环后的容量保持率为88%，5C时的高倍率性能为765mAhg−1。此外，采用100µm Li箔和贫电解液的大型面袋电池能够在70次循环后稳定855mAhg−1。这些结果很好地证明了催化脱溶对于快速的Li+迁移动力学和多硫化物的转化的有效性。
Lithium‐sulfur batteries are famous for high energy density but prevented by shuttling effect and sluggish electrochemical conversion kinetics due to the high energy barriers of Li+ transport across the electrode/electrolyte interface. Herein, the Li+‐solvents dissociation kinetics is catalyzed and stimulated by designing a carbon bridged metal‐organic framework (MOF@CC), aimed at realizing increased bare Li+ transport for the rapid conversion kinetics of sulfur species. Theoretical simulations and spectroscopic results demonstrate that the bridged MOF@CC well grants a special transport channel for accelerating Li+ benefited from aggregated anion/cation clusters. Moreover, the CN bridge between ‐NH2 ligand in MOF and carbon shell enhances electron exchange, and thus promotes polysulfide catalytic efficiency and hinder polysulfide aggregation and accumulation. With the MOF@CC‐modified separators, the assembled Li/S batteries deliver a reversible capability of 1063 mAh g‐1 at 0.5 C, a capacity retention of 88% after 100 cycles, and a high‐rate performance of 765 mAh g−1 at 5 C. Moreover, the large areal pouch cell with 100 µm Li foil and lean electrolyte is capable of stabilizing 855 mAh g−1 after 70 cycles. These results well demonstrate the efficiency of catalyzing desolvation for fast Li+ transport kinetics and the conversion of polysulfides.