Uncovering the degradation mechanism induced by ion-diffusion kinetics in large-format lithium-ion pouch cells  

作　　者：Shi Zhou Xiaohong Zhang Cong Chen Ming Chen Fanpeng Kong Yingjie Qiao Jiajun Wang 

机构地区：[1]Key Laboratory of Superlight Materials and Surface Technology,Ministry of Education,College of Materials Science and Chemical Engineering,Harbin Engineering University Harbin 150001,Heilongjiang,China [2]Chongqing Research Institute of Harbin Institute of Technology,Chongqing 401135,China

出　　处：《Journal of Energy Chemistry》2023年第8期98-105,I0005,共9页能源化学（英文版）

基　　金：supported by the Natural Science Foundation of Heilongjiang Province (LH2021E031);National Key Research and Development Program of China (2021YFB2011200);funds from Chongqing Research Institute of HIT。

摘　　要：Battery electrochemistry in an actual cell is a complicated behavior influenced by the current density,uniformity,and ion-diffusion distance,etc.The anisotropism of the lithiation/delithiation degree is usually inevitable,and even worse,due to a trend of big-size cell design,typically such as 4680 and blade cells,which accelerated a battery failure during repeat lithiation and delithiation of cathodes.Inspire by that,two big-size pouch cells with big sizes,herein,are selected to reveal the ion-diffusion dependency of the cathodes at different locations.Interestingly,we find that the LiCoO_(2) pouch cell exhibits ~5 A h loss after 120 charge-discharge cycles,but a 15 A h loss is verified in a LiNixMnyCO_(1-x)-yO_(2)(NCM) cell.Synchrotron-based imaging analysis indicates that higher ion-diffusion rates in the LiCoO_(2)than that in the LiNixMnyCO_(1-x)-yO_(2)is the determined factor for the anisotropic cathode fading,which is responsible for a severe mechanical issue of particle damage,such as cracks and even pulverization,in the cathode materials.Meanwhile,we verify the different locations at the near-tab and bottom of the electrode make it worse due to the ion-diffusion kinetics and temperature,inducing a spatially uneven electrochemistry in the big-size pouch cell.The findings give an in-depth insight into pouch cell failure and make a guideline for high-energy cell design and development.

关 键 词：Ah-level lithium-ion pouch cells Cathode materials lon-diffusion kinetics X-ray tomography 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ131.11[化学工程—无机化工]