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摘要:
Cathode electrolyte interphase (CEI) layer plays a crucial role in determining the electrochemical perfor-mance of lithium-ion batteries. Limited by the sensitive nature of CEI and the lack of characterization techniques, its dynamic evolution during cycling, its formation mechanism, and its specific impact on battery performance are not yet fully understood. Herein, we systematically investigate the dynamic evo-lution of CEI layer and its critical effect on the cycling performance of LiCoO2 cathode by diverse charac-terization techniques. We find that cycling voltage plays a key role in affecting CEI formation and evolution, and a critical potential (4.05 V vs. Li) is identified, which acts as the switching potential between CEI deposition and decomposition. We show that CEI starts deposition in the discharge process when the potential is below 4.05 V, and CEI decomposition occurs when the potential is higher than 4.05 V. When the battery is cycled below such a critical potential, a stable CEI layer is developed, which leads to superior cycling stability. When the battery is cycled above such a critical potential, a CEI-free cathode interface is observed, which also demonstrates good cycle stability. However, when the critical potential falls in the cycling voltage range, CEI deposition and decomposition are repeatedly switched on during cycling, leading to the dynamically unstable CEI layer. The unstable CEI layer causes continuous interfacial reaction and degradation, resulting in battery performance decay. Our work deepens the understanding of the CEI formation and evolution mechanisms, and clarifies the critical effect of CEI layer on cycling performance, which provides new insights into stabilizing the electrode-electrolyte interface for high-performance rechargeable batteries.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.
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来源 :
JOURNAL OF ENERGY CHEMISTRY
ISSN: 2095-4956
年份: 2023
卷: 81
页码: 192-199
1 3 . 1 0 0
JCR@2022
ESI学科: CHEMISTRY;
ESI高被引阀值:20
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