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Catalytic Disproportionation for Suppressing Polysulfide Shuttle in Li–S Pouch Cells: Beyond Adsorption Interactions
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2022-08-11 , DOI: 10.1002/aenm.202201912 Yilong Lin 1 , Yecheng Zhou 1, 2 , Sheng Huang 1 , Min Xiao 1 , Dongmei Han 1, 3 , Jiaxiang Qin 1 , Shuanjin Wang 1 , Yuezhong Meng 1
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2022-08-11 , DOI: 10.1002/aenm.202201912 Yilong Lin 1 , Yecheng Zhou 1, 2 , Sheng Huang 1 , Min Xiao 1 , Dongmei Han 1, 3 , Jiaxiang Qin 1 , Shuanjin Wang 1 , Yuezhong Meng 1
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Addressing the lithium polysulfide shuttle is critical for the high-energy-density lithium–sulfur pouch cells in practical applications, especially under high sulfur loading and lean electrolyte conditions. In contrast to previously reported heterogeneous adsorption catalysis within cathode or separator with slow catalytic kinetics and limited adsorption area, herein, lithium difluorophosphate (LiPO2F2) is demonstrated as a homogeneous catalyst in electrolyte which mitigates polysulfide diffusion. The Li–S pouch cell with LiPO2F2 in the electrolyte has record-breaking shelving stability of two months, significantly improved capacity retention from 37.0% to 81.4% after long cycling, and electrical-car-level energy density over 400 Wh kg−1. A minimal amount of 1 wt% LiPO2F2 tends to facilitate lithium polysulfide disproportionation on the S/C cathode instead of in the electrolyte, which initiates the fast transformation of soluble lithium polysulfide to insoluble solid S8 and Li2S2/Li2S. The reliable mechanism of polysulfide disproportionation via biradicals is further proposed by both density functional theory calculation and experiments. To best of the authors’ knowledge, this is the first report on mechanism of polysulfide disproportionation via biradical intermediates. It is believed that this new insight into homogeneous catalytic mechanisms in electrolytes may pave the way for the commercialization of high-energy-density Li–S batteries.
中文翻译：
用于抑制 Li-S 软包电池中多硫化物穿梭的催化歧化：超越吸附相互作用
解决多硫化锂穿梭问题对于实际应用中的高能量密度锂硫软包电池至关重要，尤其是在高硫负载和贫电解质条件下。与之前报道的具有缓慢催化动力学和有限吸附面积的阴极或隔膜内的非均相吸附催化相比，本文证明二氟磷酸锂 (LiPO 2 F 2 ) 是电解质中的均相催化剂，可减轻多硫化物的扩散。含 LiPO 2 F 2的 Li-S 软包电池在电解液中具有创纪录的两个月搁置稳定性，长时间循环后容量保持率从 37.0% 显着提高至 81.4%，电动汽车级能量密度超过 400 Wh kg -1。最小量的 1 wt% LiPO 2 F 2倾向于促进多硫化锂在 S/C 正极上而不是在电解液中歧化，从而引发可溶性多硫化锂快速转变为不溶性固体 S 8和 Li 2 S 2 /Li 2S.通过密度泛函理论计算和实验进一步提出了多硫化物通过双自由基歧化的可靠机理。据作者所知，这是关于多硫化物通过双自由基中间体歧化机理的第一份报告。相信这种对电解质中均相催化机制的新见解可能为高能量密度锂硫电池的商业化铺平道路。
更新日期：2022-08-11
中文翻译：
用于抑制 Li-S 软包电池中多硫化物穿梭的催化歧化：超越吸附相互作用
解决多硫化锂穿梭问题对于实际应用中的高能量密度锂硫软包电池至关重要，尤其是在高硫负载和贫电解质条件下。与之前报道的具有缓慢催化动力学和有限吸附面积的阴极或隔膜内的非均相吸附催化相比，本文证明二氟磷酸锂 (LiPO 2 F 2 ) 是电解质中的均相催化剂，可减轻多硫化物的扩散。含 LiPO 2 F 2的 Li-S 软包电池在电解液中具有创纪录的两个月搁置稳定性，长时间循环后容量保持率从 37.0% 显着提高至 81.4%，电动汽车级能量密度超过 400 Wh kg -1。最小量的 1 wt% LiPO 2 F 2倾向于促进多硫化锂在 S/C 正极上而不是在电解液中歧化，从而引发可溶性多硫化锂快速转变为不溶性固体 S 8和 Li 2 S 2 /Li 2S.通过密度泛函理论计算和实验进一步提出了多硫化物通过双自由基歧化的可靠机理。据作者所知，这是关于多硫化物通过双自由基中间体歧化机理的第一份报告。相信这种对电解质中均相催化机制的新见解可能为高能量密度锂硫电池的商业化铺平道路。
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