Enhancing anionic redox stability via oxygen coordination configurations

Haoxin Li; Yining Li; Xiaolin Zhao; Yang Gan; Wujie Qiu; Jianjun Liu

doi:10.1039/d3mh00568b

Enhancing anionic redox stability via oxygen coordination configurations

Mater Horiz. 2023 Aug 29;10(9):3729-3739. doi: 10.1039/d3mh00568b.

Authors

Haoxin Li^{1

2

3}, Yining Li^{2

3}, Xiaolin Zhao^{2

3}, Yang Gan^{2

3}, Wujie Qiu^{2

3}, Jianjun Liu^{1

2

3}

Affiliations

¹ School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, 1 Sub-lane Xiangshan, Hangzhou, 310024, China. jliu@mail.sic.ac.cn.
² State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, China. wjqiu@mail.sic.ac.cn.
³ Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.

PMID: 37405377
DOI: 10.1039/d3mh00568b

Abstract

Anionic redox in Li-rich cathode materials with disordered crystal structures has potential to increase battery energy density. However, capacity fading due to anionic redox-induced structural transformation hinders practical implementation. To address this challenge, it is crucial to understand the influence of the anion coordination structure on redox reversibility. By comprehensively studying the spinel-like Li_1.7Mn_1.6O_3.7F_0.3 and layered Li₂MnO₃ model systems, we found that tetrahedral oxygen exhibits higher kinetic and thermodynamic stability than octahedral oxygen in Li_1.7Mn_1.6O_3.7F_0.3 and Li₂MnO₃, effectively suppressing aggregation of oxidized anions. Electronic structure analysis showed that the 2p lone-pair states in tetrahedral oxygen lie deeper than those in octahedral oxygen. The Li-O-TM bond angle in a polyhedron is identified as a characteristic parameter to correlate anionic redox stability. TM substitutions using Co³⁺, Ti⁴⁺ and Mo⁵⁺ could effectively regulate the Li-O-Mn bond angle and anionic active electronic state. Our finding that anionic redox stability is influenced by the polyhedral structure offers new opportunities for designing high-energy-density Li-rich cathode materials.