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Spatial and Kinetic Regulation of Sulfur Electrochemistry on Semi-Immobilized Redox Mediators in Working Batteries |
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| Authors: | Jin Xie Dr. Hong-Jie Peng Yun-Wei Song Dr. Bo-Quan Li Ye Xiao Meng Zhao Dr. Hong Yuan Prof. Jia-Qi Huang Prof. Qiang Zhang |
| Affiliation: | 1. Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 P. R. China These authors contributed equally to this work.;2. Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084 P. R. China;3. School of Materials Science & Engineering, Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing, 100084 P. R. China |
| Abstract: | Use of redox mediators (RMs) is an effective strategy to enhance reaction kinetics of multi-electron sulfur electrochemistry. However, the soluble small-molecule RMs usually aggravate the internal shuttle and thus further reduce the battery efficiency and cyclability. A semi-immobilization strategy is now proposed for RM design to effectively regulate the sulfur electrochemistry while circumvent the inherent shuttle issue in a working battery. Small imide molecules as the model RMs were co-polymerized with moderate-chained polyether, rendering a semi-immobilized RM (PIPE) that is spatially restrained yet kinetically active. A small amount of PIPE (5 % in cathode) extended the cyclability of sulfur cathode from 37 to 190 cycles with 80 % capacity retention at 0.5 C. The semi-immobilization strategy helps to understand RM-assisted sulfur electrochemistry in alkali metal batteries and enlightens the chemical design of active additives for advanced electrochemical energy storage devices. |
| Keywords: | cathode electrochemistry kinetics regulation lithium–sulfur batteries redox mediators sulfur redox reactions |