文献类型：期刊文献

英文题名：Study on the intergranular cracks evolution and mechanisms in PC-NCM811 particles through long-term real-time observation

作者：Yao, Yiming[1,3];Chen, Ying[1];Yao, Zhiheng[1];Liu, Zexuan[1];Chen, Haofeng[1,2];Li, Hailong[3];Luan, Weiling[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Adv Battery Syst & Safety CPCIF, Shanghai 200237, Peoples R China;[2]Univ Strathclyde, Dept Mech & Aerosp Engn, Glasgow G1 1XJ, Scotland;[3]Malardalen Univ, Sch Business Soc & Engn, SE-72123 Vasteras, Sweden

年份：2024

卷号：102

外文期刊名：JOURNAL OF ENERGY STORAGE

收录：;EI(收录号：20244217196931);WOS:【SCI-EXPANDED(收录号:WOS:001369208700001)】；

基金：The authors gratefully acknowledge the support from the National Natural Science Foundation of China (52375144 and 52205153) , Shanghai Pujiang Programme (23PJD019) during the course of this work.

语种：英文

外文关键词：NCM; Intergranular crack; Real-time observation; Crack evolution; Lithium-ion diffusion

摘要：Nickel-rich polycrystalline LiNixCoyMn1-x-yO2 (PC-NCM, 0.8 <= x < 1) particles suffer capacity degradation due to intergranular cracks, which catalyze side reactions at fresh interfaces, diminishing battery performance. Understanding the mechanisms behind crack evolution is essential for mitigating these issues. Real-time crack observation is crucial for this understanding, yet long-term monitoring remains unachieved. This study develops a versatile method using an optical in-situ reaction cell, modified from a coin cell structure, to enable long-term, real-time tracking of volume changes, crack evolution and lithium-ion diffusion in the particle. This method has provided new insights into the evolution of intergranular cracks and mechanisms in PC-NCM811 particles. Intergranular cracks can be categorized into main cracks, microcracks and cracks at the boundaries of inactive domains based on the stress origin. Main cracks stem from strain mismatches caused by asynchronous domains during initial activation, while their subsequent propagation is driven by alternating stresses from cycling. The initiation of microcracks is caused by stress concentration at grain boundaries due to abrupt volume contraction during charging process. Volume changes along the a-axis exacerbate the irreversible propagation of these microcracks at a high state of charge. Optical imaging shows regions with limited lithium-ion diffusion align with boundary cracks caused by uneven lithium-ion concentrations at high C-rate. These findings emphasize the value of long-term, real-time observation for understanding electrochemical-mechanical interactions. The observation and analysis method can be applied to investigate and evaluate the crack evolution of various materials under different conditions, facilitating the optimization of material design and the formulation of effective cycling protocols.