Catalytic Disproportionation for Suppressing Polysulfide Shuttle in Li–S Pouch Cells: Beyond Adsorption Interactions. Issue 37 (11th August 2022)

• Record Type: Journal Article
• Authors: Lin, Yilong; Zhou, Yecheng; Huang, Sheng; Xiao, Min; Han, Dongmei; Qin, Jiaxiang; Wang, Shuanjin; Meng, Yuezhong
• Is Part Of: Advanced energy materials. Volume 12:Issue 37(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-08-11
• Subjects: biradicals -- DFT calculations -- disproportionation -- homogeneous catalysts -- lithium–sulfur batteries -- polysulfide shuttle; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202201912
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: 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 (LiPO2 F2 ) is demonstrated as a homogeneous catalyst in electrolyte which mitigates polysulfide diffusion. The Li–S pouch cell with LiPO2 F2 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% LiPO2 F2 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 Li2 S2 /Li2 S. 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. Abstract : A homogeneous catalyst enables catalytic disproportionation for suppressing polysulfide shuttle to improve the electrochemical performance of Li–S pouch cells.