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

21 May 2024, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

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-.

Keywords

Interface charge-transfer kinetics
Coupled ion-electron transfer
Li-ion batteries
Constrained density functional theory
Constant potential calculations

Supplementary materials

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Supporting information
Description
Computational and modeling details; parameter sensitivity analysis CIET simulations; density of states plots; Li vacancy formation energies; polarization curve at x=1.00; reorganization energy analysis.
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