锂金属电极与LiCl界面相互作用的第一性原理研究

First⁃principles Study on the Interface Interaction of Li and LiCl in Lithium Metal Batteries

锂金属因具有高理论容量及低还原电势等优点,是最具潜力的下一代高能量密度电池负极材料。但金属锂具有活跃的化学特性,在电池中易与电解质发生反应,导致锂枝晶的生长,进而使锂电池发生短路,影响其使用。研究表明,在固态电解质界面(SEI)膜形成过程中添加LiF可以调控锂在表面沉积的形貌,稳定电极/电解质界面,但机理尚不明确。本工作拟采用基于密度泛函理论的第一性原理研究方法,构建了金属Li和LiCl表面模型,通过对该模型电子态密度、Li在LiCl表面的吸附能以及Li在LiCl表面的扩散能垒等的计算,研究发现在SEI中添加LiCl可以对锂金属负极起到保护作用,为探索锂金属电池体系中稳定锂金属负极及界面保护材料的设计提供了新思路。

Due to its high theoretical capacity and low reduction potential, lithium metal is the most potential anode material of the next generation high energy density batteries. However, lithium metal reacts easily with electrolyte in the battery because of its active chemical properties, leading to the growth of lithium dendrite, which in turn occurs short circuit of lithium battery and affects its use. Studies have shown that adding LiF during the formation of the solid electrolyte interface membrane(SEI) can control the morphology of lithium deposition on the surface and stabilize the electrode/electrolyte interface, but the mechanism is still unclear. By using first-principles methods based on density functional theory, this work studied a metal Li and LiCl interface model, calculated the structure’s electronic density of states, the adsorption energy of Li on the surface of LiCl, and the diffusion barrier of Li on LiCl surface, analyzed the mechanism of the interface interaction, it is found that the addition of LiCl in SEI can protect the lithium metal anode. It provides new ideas for designing of stable lithium metal anodes and interface protection materials in lithium metal battery systems.