First principles studies of self-diffusion processes on metallic lithium surfaces

Abstract

Due to the theoretical high specific capacity (3860 mAh/g) and the low standard electrode potential (-3.040 V vs. standard hydrogen electrode), rechargeable lithium metal batteries are considered as excellent energy storage systems. Unfortunately, security concerns related to dendrite formation during charge/discharge cycles still hinder the commercial use of Li metal-based batteries. Using density functional theory, we have studied the bulk and surface properties of metallic lithium at an atomistic level. In this process, bcc Li(100) proved to be the most stable metallic lithium surface. Subsequently, possible self-diffusion mechanisms on perfect and imperfect Li(100) surfaces were examined. For this purpose, nudged elastic band calculations were performed to characterize the respective diffusion processes and to determine the relevant pre-exponential factors and activation barriers. On the basis of the acquired data, it became possible to derive activation temperatures and reaction rates for the respective processes, which are useful for experimental verification as well as for the implementation in long-scale kinetic Monte Carlo simulations.