Inhibition of oxygen dimerization by local symmetry tuning in Li-rich layered oxides for improved stability.

Ning, Fanghua; Li, Biao; Song, Jin; Zuo, Yuxuan; Shang, Huaifang; Zhao, Zimeng; Yu, Zhen; Chu, Wangsheng et al. · Nat Commun · 2020

basic_science · Level V

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Abstract

Li-rich layered oxide cathode materials show high capacities in lithium-ion batteries owing to the contribution of the oxygen redox reaction. However, structural accommodation of this reaction usually results in O-O dimerization, leading to oxygen release and poor electrochemical performance. In this study, we propose a new structural response mechanism inhibiting O-O dimerization for the oxygen redox reaction by tuning the local symmetry around the oxygen ions. Compared with regular Li<sub>2</sub>RuO<sub>3</sub>, the structural response of the as-prepared local-symmetry-tuned Li<sub>2</sub>RuO<sub>3</sub> to the oxygen redox reaction involves the telescopic O-Ru-O configuration rather than O-O dimerization, which inhibits oxygen release, enabling significantly enhanced cycling stability and negligible voltage decay. This discovery of the new structural response mechanism for the oxygen redox reaction will provide a new scope for the strategy of enhancing the anionic redox stability, paving unexplored pathways toward further development of high capacity Li-rich layered oxides.