材料科学
阴极
相(物质)
离子
电化学
衍射
氧化物
化学工程
分析化学(期刊)
化学物理
电极
热力学
化学
物理化学
冶金
光学
物理
工程类
有机化学
色谱法
作者
Lea de Biasi,Alexander Schiele,M. Roca-Ayats,Gonzalo Rodríguez García,Torsten Brezesinski,Pascal Hartmann,Jürgen Janek
出处
期刊:Chemsuschem
[Wiley]
日期:2019-04-04
卷期号:12 (10): 2240-2250
被引量:162
标识
DOI:10.1002/cssc.201900032
摘要
Abstract Ni‐rich layered oxide cathode materials, in particular the end member LiNiO 2 , suffer from drawbacks such as high surface reactivity and severe structural changes during de‐/lithiation, leading to accelerated degradation and limiting practical implementation of these otherwise highly promising electrode materials in Li‐ion batteries. Among all known phase transformations occurring in LiNiO 2 , the one from the H2 phase to the H3 phase at high state of charge is believed to have the most detrimental impact on the material's stability. In this work, the multistep phase transformation process and associated effects are analyzed by galvanostatic cycling, operando X‐ray diffraction, and in situ pressure and gas analysis. The combined results provide thorough insights into the structural changes and how they affect the stability of LiNiO 2 . During the H2–H3 transformation, the most significant change occurs in the c ‐lattice parameter, resulting in large mechanical stress in LiNiO 2 . As for electrochemical stability, it suffers strongly in the H3 region. Oxygen evolution is observed not only during charge but also during discharge and found to be correlated with the presence of the H2 and H3 phases. Taken together, the experimental data improve the understanding of the degradation processes and the inherent instability of LiNiO 2 in Li‐ion cells when operated above around 75 % state of charge.
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