Study on the dynamics of a vanadium doped LiFePO₄ lithium-ion battery using quasi-elastic neutron scattering technique

The investigation into the lithium diffusion in active electrode materials is especially interesting since it is directly connected with electrochemical performance of lithium-ion battery. Quasi-elastic neutron scattering (QENS) is a powerful experimental tool to study lithium diffusion dynamics. Here, Li_0.99V0_.01FePO₄ (LFPV) cathode material is investigated using QENS technique. The QENS data showed that lithium diffusion can be well described in LFPV using a jump diffusion model. The Li self-diffusion coefficient in LFPV material was estimated to be ~3 × 10⁻⁷ cm²/s at T = 600 K. This result is about 10⁸ times faster than previous reports using electrochemical measurements, but similar to the molecular dynamic simulation. The slower Li ion diffusion might be due to the barrier at two phase boundary, grain boundary, and solid-electrolyte interface.