Ab Initio Modeling of Transition Metal Dissolution from the LiNi0.5Mn1.5O4 Cathode.

Abstract

Irreversible dissolution of transition metals (TMs) from cathode materials in lithium-ion batteries (LIBs) represents a serious challenge for the application of high-energy-density LIBs. Despite substantial improvements achieved by Ni doping of the LiMn2O4 spinel, the promising high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode material still suffers from the loss of electro-active materials (Mn and Ni). This process contributes to the formation of solid-electrolyte interfaces and capacity loss severely limiting the battery life cycle. Here, we combine static and ab initio molecular dynamics free energy calculations based on the density functional theory to investigate the mechanism and kinetics of TM dissolution from LNMO into the liquid organic electrolyte. Our calculations help deconvolute the impact of various factors on TM dissolution rates such as the presence of surface protons and oxygen vacancies and the nature of TMs and electrolyte species. The present study also reveals a linear relationship between adsorption strength of the electrolyte species and TM dissolution barriers that should help design electrode/electrolyte interfaces less vulnerable to TM dissolution.