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

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.