Effect of antisite defects on Li ion diffusion in LiNiPO4: A first principles study

Abstract

Lithium diffusion properties in crystalline LiNiPO4 were studied using density functional theory. Formation and clustering energies of Li-Ni antisite defects are calculated, results showed the antisite defects are energetically favorable in the LiNiPO4 and they not tend to bind together. The energy barrier of Li is 0.28 eV in the pristine LiNiPO4. The energy barriers of Li diffusion along the [010] direction in the LiNiPO4 were not affected so much compared with that in the pristine system, however, the diffusion energy barrier of Ni diffusion was much larger than that of Li. This indicates that the existence of antisite defect will severely impede Li diffusion along the [010] direction and thus explains the poor cycling performance of LiNiPO4 cathode materials for LIBs.