Computational Insights into Electrolyte-Dependent Li-ion Charge-Transfer Kinetics at the LixCoO2 Interface

Abstract

Interface engineering remains a largely underexplored area and yet it holds the keys to high performance Li-ion batteries. It is the charge transfer across electrode-electrolyte interfaces, its inefficient energetics and sluggish kinetics that are oftentimes significant obstacles for achieving fast charging and high power regimes without compromising battery lifespan. This work propose a Boltzmann-averaged first principles workflow based on constant potential and constrained density functional theory for estimation of atomic scale factors influencing coupled ion-electron charge transfer kinetics across battery electrode-electrolyte interfaces. The approach estimates diabatic Li+ interface energy landscapes as function of the interface character and operational conditions, needed to simulate charging/discharging currents. Experimental trends for the LixCoO2 (0.5≤x≤1.0) electrode in varied organic electrolytes with LiPF6 and LiClO4 salts are reproduced, identifying Li+ transfer energy and Li+ adsorption energy as decisive factors influencing the enhanced kinetics in LiClO4-based electrolytes over LiPF6, rationalized by a stronger surface interaction of ClO4-.