铜
空位缺陷
晶界
扩散
离子
电化学
化学物理
惰性
溶解
材料科学
晶体缺陷
化学
冶金
电极
结晶学
热力学
物理化学
微观结构
物理
有机化学
作者
A.I. Kartamyshev,D.O. Poletaev,A.O. Boev,Dmitry A. Aksyonov
标识
DOI:10.1016/j.commatsci.2023.112517
摘要
Adoption of Li-ion batteries for stationary energy storage requires to prolong their operational lifetimes to several decades calling to inhibit all degradation mechanisms. One of such mechanisms is associated with gradual formation of Cu–Li alloys at copper current collector - a component traditionally assumed inert in a Li-ion cell. Recent studies shows that Li can penetrate inside a Cu upon electrochemical cycling. We demonstrate that this process may be strongly intensified due to the presence of grain boundaries (GB) in copper. Using density functional theory calculations, we discover that Li segregate at copper GBs, which facilitates its GB diffusion according to vacancy-assisted mechanism. The vacancy formation and migration energies at GBs are significantly decreased in comparison to the values in bulk copper causing strong accelerating of Li diffusion. The segregation is caused by atomic-size effect, while the decrease of migration barriers is explained by a more stable coordination of ionized Li at a saddle point. To prevent Li penetration and subsequent formation of Li–Cu alloys, the amount of grain boundaries in thin film copper current collectors should be minimized.
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