Revealing the Origin of Transition‐Metal Migration in Layered Sodium‐Ion Battery Cathodes: Random Na Extraction and Na‐Free Layer Formation. (9th February 2023)

• Record Type: Journal Article
• Authors: Chu, Shiyong; Kim, Duho; Choi, Gwanghyeon; Zhang, Chunchen; Li, Haoyu; Pang, Wei Kong; Fan, Yameng; D'Angelo, Anita M.; Guo, Shaohua; Zhou, Haoshen
• Is Part Of: Angewandte Chemie. Volume 135:Number 12(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-09
• Subjects: Layered Sodium-Ion Battery Cathodes -- Na-Free Layer -- Random Na Extraction -- Selective Na Extraction -- Transition-Metal Migration; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202216174
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Cation migration often occurs in layered oxide cathodes of lithium‐ion batteries due to the similar ion radius of Li and transition metals (TMs). Although Na and TM show a big difference of ion radius, TMs in layered cathodes of sodium‐ion batteries (SIBs) can still migrate to Na layer, leading to serious electrochemical degeneration. To elucidate the origin of TM migration in layered SIB cathodes, we choose NaCrO2, a typical layered cathode suffering from serious TM migration, as a model material and find that the TM migration is derived from the random desodiation and subsequent formation of Na‐free layer at high charge potential. A Ru/Ti co‐doping strategy is developed to address the issue, where the doped active Ru is first oxidized to create a selective desodiation and the doped inactive Ti can function as a pillar to avoid complete desodiation in Ru‐contained TM layers, leading to the suppression of the Na‐free layer formation and subsequent enhanced electrochemical performance. Abstract : The origin of cation migration in layered sodium‐ion battery cathode is first elucidated, which is attributed to the Na‐free layer forming under high charge potential due to the random desodiation reaction. A 3 d /4 d metal co‐doping strategy is developed to address the unfavourable cation migration by creating a selective desodiation reaction.