Localizing Oxygen Lattice Evolutions Eliminates Oxygen Release and Voltage Decay in All‐Mn‐Based Li‐Rich Cathodes

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 19; no. 18; pp. e2300419 - n/a
• Main Authors: Wu, Kang, Zhao, Enyue, Ran, Peilin, Yin, Wen, Zhang, Zhigang, Wang, Bao‐Tian, Ikeda, Kazutaka, Otomo, Toshiya, Xiao, Xiaoling, Wang, Fangwei, Zhao, Jinkui
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.05.2023
• Subjects: anionic redox chemistry; Cathodes; Cycles; Distribution functions; Electric potential; Li‐rich Li–Mn–O cathodes; Nanotechnology; Oxygen; oxygen lattice evolution; Phase transitions; Redox reactions; stacking faults; Voltage; voltage decay; anionic redox chemistry; Li-rich Li-Mn-O cathodes; stacking faults; oxygen lattice evolution; voltage decay
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202300419

All‐Mn‐based Li‐rich cathodes Li2MnO3 have attracted extensive attention because of their cost advantage and ultrahigh theoretical capacity. However, the unstable anionic redox reaction (ARR), which involves irreversible oxygen releases, causes declines in cycling capacity and intercalation potential, thus hindering their practical applications. Here, it is proposed that introducing stacking‐fault defects into the Li2MnO3 can localize oxygen lattice evolutions and stabilize the ARR, eliminating oxygen releases. The thus‐made cathode has a highly reversible capacity (320 mA h g−1) and achieves excellent cycling stability. After 100 cycles, the capacity retention rate is 86% and the voltage decay is practically eliminated at 0.19 mV per cycle. Attributing to the stable ARR, samples show reduced stress–strain and phase transitions. Neutron pair distribution function (nPDF) measurements indicate that there is a structure response of localized oxygen lattice distortion to the ARR and the average oxygen lattice framework is well‐preserved which is a prerequisite for the high cycle reversibility. Unlike global oxygen lattice distortions observed in a layered structure without stacking‐fault defects, localized oxygen lattice distortions can be driven by a stacking‐fault layered structure in Li‐rich layered oxide cathodes. The localized lattice distortions disperse stress distributions and well preserve the global oxygen lattice framework, thus stabilizing lattice oxygen redox reactions with practically eliminated oxygen release.