# Influence of elastic strain on the thermodynamics and kinetics of lithium vacancy in bulk LiCoO2

## TL;DR

This study uses first-principles calculations to show how elastic strain significantly impacts lithium vacancy behavior and ionic conductivity in LiCoO2, affecting battery performance.

## Contribution

It provides a detailed analysis of strain effects on vacancy formation and migration in LiCoO2 using DFT and elasticity theory, highlighting their impact on battery efficiency.

## Key findings

- Elastic strain can change ionic conductivity by an order of magnitude.
- Strain influences vacancy formation and migration energies.
- Elastic dipole tensor effectively predicts strain effects.

## Abstract

The influence of elastic strain on the lithium vacancy formation and migration in bulk LiCoO2 is evaluated by means of first-principles calculations within density functional theory (DFT). Strain dependent energies are determined directly from defective cells and also within linear elasticity theory from the elastic dipole tensor (Gij) for ground state and saddle point configurations. We analyze finite size-effects in the calculation of Gij, compare the predictions of the linear elastic model with those obtained from direct calculations of defective cells under strain and discuss the differences. Based on our data, we calculate the variations in vacancy concentration and mobility due to the presence of external strain in bulk LiCoO2 cathodes. Our results reveal that elastic in-plane and out-of-plane strains can significantly change the ionic conductivity of bulk LiCoO2 by an order of magnitude and thus strongly affect the performance of Li-secondary batteries.