First principles study on electronic properties and occupancy sites of molybdenum doped into LiFePO4

The electronic properties of Mo-doped LiFePO4 and occupancy sites of Mo are investigated by employing the density functional theory plane-wave pseudopotential method. The calculated results show that Mo doping at Fe site has lower formation energy, which implies that Mo dopants prefer to occupy Fe sites within the LiFePO4 lattice. Furthermore, the LiFe1−3/12Mo1/12PO4 has wider lithium ion migration channels than Li1−6/12Mo1/12FePO4. For the case of LiFe1−3/12Mo1/12PO4, the calculated narrow band gap (0.18 eV) indicates that the electronic conductivity of LiFePO4 could be enhanced by doping Mo at the Fe sites. The density of states and charge densities of LiFe1−3/12Mo1/12PO4 demonstrate that the Mo-4d states and MoO bonding play important roles in band gap reduction of LiFe1−3/12Mo1/12PO4.