Yoon Jeong Seop, Liao Daniel W, Greene Samuel M, Cho Tae H, Dasgupta Neil P, Siegel Donald J
Department of Mechanical Engineering, University of Michigan, 2350 Hayward Avenue, Ann Arbor, Michigan 48109, United States.
Oden Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712-1591, United States.
ACS Appl Mater Interfaces. 2024 Apr 17;16(15):18790-18799. doi: 10.1021/acsami.3c19034. Epub 2024 Apr 8.
A rechargeable battery that employs a Li metal anode requires that Li be plated in a uniform fashion during charging. In "anode-free" configurations, this plating will occur on the surface of the Cu current collector (CC) during the initial cycle and in any subsequent cycle where the capacity of the cell is fully accessed. Experimental measurements have shown that the plating of Li on Cu can be inhomogeneous, which can lower the efficiency of plating and foster the formation of Li dendrites. The present study employs a combination of first-principles calculations and sessile drop experiments to characterize the thermodynamics and adhesive (, wetting) properties of interfaces involving Li and other phases present on or near the CC. Interfaces between Li and Cu, CuO, and LiO are considered. The calculations predict that both Cu and CuO surfaces are lithiophilic. However, sessile drop measurements reveal that Li wetting occurs readily only on pristine Cu. This apparent discrepancy is explained by the occurrence of a spontaneous conversion reaction, 2 Li + CuO → LiO + 2 Cu, that generates LiO as one of its products. Calculations and sessile drop measurements show that Li does not wet (newly formed) LiO. Hence, Li that is deposited on a Cu CC where surface oxide species are present will encounter a compositionally heterogeneous substrate comprising lithiophillic (Cu) and lithiophobic (LiO) regions. These initial heterogeneities have the potential to influence the longer-term behavior of the anode under cycling. In sum, the present study provides insights into the early stage processes associated with Li plating in anode-free batteries and describes mechanisms that contribute to inefficiencies in their operation.
采用锂金属阳极的可充电电池要求在充电过程中锂以均匀的方式沉积。在“无阳极”配置中，这种沉积将在初始循环期间以及在电池容量被完全利用的任何后续循环中发生在铜集流体（CC）的表面上。实验测量表明，锂在铜上的沉积可能是不均匀的，这会降低沉积效率并促进锂枝晶的形成。本研究结合第一性原理计算和 sessile drop 实验来表征涉及锂以及 CC 上或其附近存在的其他相的界面的热力学和粘附（即润湿性）特性。考虑了锂与铜、氧化铜和氧化锂之间的界面。计算预测铜和氧化铜表面都是亲锂的。然而，sessile drop 测量表明锂仅在原始铜上容易发生润湿。这种明显的差异是由自发转化反应 2 Li + CuO → LiO + 2 Cu 的发生来解释的，该反应产生氧化锂作为其产物之一。计算和 sessile drop 测量表明锂不会润湿（新形成的）氧化锂。因此，沉积在存在表面氧化物物种的铜 CC 上的锂将遇到由亲锂（铜）和亲锂性（氧化锂）区域组成的成分不均匀的基底。这些初始的不均匀性有可能影响阳极在循环下的长期行为。总之，本研究提供了对无阳极电池中与锂沉积相关的早期过程的见解，并描述了导致其运行效率低下的机制。
