Xie Jia, Xue Jing, Wang Hongyi, Li Jingze
Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China, Huzhou 313001, P. R. China.
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 611731, P. R. China.
Phys Chem Chem Phys. 2023 Nov 8;25(43):29797-29807. doi: 10.1039/d3cp03713d.
A Li alloy based artificial coating layer can improve the cyclic performance of Li metal anodes. However, the protective mechanism is not well clarified due to multiple components of the artificial layer and complicated interface in liquid electrolytes. Herein, a single-component LiSn alloy layer buffered Li anode is paired with a solid-state polymer electrolyte, where a metallic Sn film is sputtered onto the Li anode and the subsequent alloying reaction leads to the formation of a LiSn phase. During the striping/plating process, the thickness and composition of the Li-Sn alloy passivation layer remain unchanged. Meanwhile, Li ions are reduced on the top surface of the LiSn layer, then the reduced Li atoms immediately pass through the alloy layer, and finally dense Li deposition occurs beneath the protective layer, realizing spatial isolation of the electrochemical reduction of Li from Li nucleation/growth. This unique protection mechanism can principally avoid the formation of Li dendrites and efficiently mitigate irreversible reactions between the Li anode and the polymer electrolyte. The synergistic effects lead to a clean and flat surface of the protected Li electrode, enabling a prolonged cycle lifetime over 1300 h at 25 °C at 0.1 mA cm and 0.1 mA h cm in a configuration of symmetrical cells.
基于锂合金的人工涂层可以改善锂金属负极的循环性能。然而，由于人工层的多组分以及液体电解质中复杂的界面，其保护机制尚未得到很好的阐明。在此，一种单组分锂锡合金层缓冲锂负极与固态聚合物电解质配对，其中在锂负极上溅射金属锡膜，随后的合金化反应导致形成锂锡相。在脱嵌/镀锂过程中，锂锡合金钝化层的厚度和组成保持不变。同时，锂离子在锂锡层的顶表面被还原，然后被还原的锂原子立即穿过合金层，最终在保护层下方发生致密的锂沉积，实现了锂的电化学还原与锂成核/生长的空间隔离。这种独特的保护机制原则上可以避免锂枝晶的形成，并有效减轻锂负极与聚合物电解质之间的不可逆反应。协同效应使得被保护的锂电极表面干净且平整，在对称电池配置中，于25℃、0.1 mA cm和0.1 mA h cm条件下可实现超过1300小时的长循环寿命。
