Wu Kang, Zhao Enyue, Ran Peilin, Yin Wen, Zhang Zhigang, Wang Bao-Tian, Ikeda Kazutaka, Otomo Toshiya, Xiao Xiaoling, Wang Fangwei, Zhao Jinkui
Songshan Lake Materials Laboratory, Dongguan, 523808, China.
Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
Small. 2023 May;19(18):e2300419. doi: 10.1002/smll.202300419. Epub 2023 Feb 1.
All-Mn-based Li-rich cathodes Li MnO 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 Li MnO 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 ) 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.
所有基于锰的富锂正极材料LiMnO因其成本优势和超高理论容量而备受关注。然而，涉及不可逆氧释放的不稳定阴离子氧化还原反应（ARR）会导致循环容量和嵌入电位下降，从而阻碍其实际应用。在此，有人提出在LiMnO中引入堆垛层错缺陷可以使氧晶格演化局部化并稳定ARR，消除氧释放。由此制成的正极具有高度可逆容量（320 mA h g）并实现了出色的循环稳定性。100次循环后，容量保持率为86%，电压衰减实际上消除，每循环为0.19 mV。由于ARR稳定，样品显示出降低的应力应变和相变。中子对分布函数（nPDF）测量表明，存在局部氧晶格畸变对ARR的结构响应，并且平均氧晶格框架保存良好，这是高循环可逆性的先决条件。
