A New Insight into the Polaron-Li Complex Diffusion in Cathode Material LiFe1-yMnyPO4 for Li Ion Batteries

Based on the Heyd-Scuseria-Ernzerhof hybrid density functionals study, we proposed a new insight into the diffusion of polaron-Li vacancy complexes in LiFe1-yMnyPO4 (y = 0, 1/2, 1). It is found that the polaron migrates along a crossing or a parallel path relative to the Li moving direction. In LiFePO4, the complex diffusion along the zigzag pathway is favorable and has a barrier of 600 meV, while the diffusion along the parallel pathway with a barrier of 623 meV is favorable in LiMnPO4. For LiFe1/2Mn1/2PO4, since the polaron is formed within a single Fe layer, the diffusion proceeds along the parallel pathway with a barrier of 635 meV. (C) 2012 The Japan Society of Applied Physics