Lithium diffusion in Li1−xFePO4: the effect of cationic disorder

Abstract

LiFePO₄ is a key material in the field of rechargeable lithium batteries. In this study the transport properties of partially delithiated LiFePO₄ are investigated by molecular dynamics simulations, giving particular emphasis to the effect of the presence of Li–Fe anti-site defects on the mechanisms of Li⁺ diffusion in the structure, with the aim to deepen the comprehension of the connection between cationic disorder and dimensionality of Li⁺ ion transport in this system. The main results indicate that Li diffusion in the system is preferentially anisotropic, with the [0 1 0] direction being the most favourable one. However, Li migration along different directions is possible under specific circumstances, as the Li–Fe anti-site defects effectively act as centres promoting the crossing between adjacent channels running along the [0 1 0] direction.