期刊
ENERGY STORAGE MATERIALS
卷 36, 期 -, 页码 115-122出版社
ELSEVIER
DOI: 10.1016/j.ensm.2020.12.018
关键词
in situ STEM; Lithium ion batteries; Layered lithium transition metal oxides; Oxygen release; Local heterogeneity
资金
- National Natural Science Foundation of China [22005230, 21905169]
- Fundamental Research Funds for the Central Universities [WUT: 2019III012GX, 2020III002GX]
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing at Wuhan University of Technology
- State Key Laboratory of Silicate Materials for Architectures at Wuhan University of Technology
This study reveals the origin of heterogeneous oxygen release in layered cathodes and provides insights for the rational design of cathode materials with enhanced oxygen stability by suppressing cation migration.
The irreversible release of the lattice oxygen in layered cathodes is one of the major degradation mechanisms of lithium ion batteries, which accounts for a number of battery failures including the voltage/capacity fade, loss of cation ions and detachment of the primary particles, etc. Oxygen release is generally attributed to the stepwise thermodynamic controlled phase transitions from the layered to spinel and rock salt phases. Here, we report a strong kinetic effect from the mobility of cation ions, whose migration barrier can be significantly modulated by the phase epitaxy at the degrading interface. It ends up with a clear oxygen release heterogeneity and completely different reaction pathways between the thin and thick areas, as well as the interparticle valence boundaries, both of which widely exist in the mainstream cathode design with the secondary agglomerates. This work unveils the origin of the heterogenous oxygen release in the layered cathodes. It also sheds light on the rational design of cathode materials with enhanced oxygen stability by suppressing the cation migration.
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