The high rate capability and structural stability of the olivine phosphates attracted a lot of interest as promising cathode materials for high energy density batteries. Alteration on these cathode materials, for instance, reducing particle size, conductive coating and metal ion doping were performed in order to improve the conductivity and to obtain high specific Li + diffusion. However, the drastic improvement in electrical conductivity for the aliovalent doping is still unclear. Rather writing a lengthy standard review, this manuscript intends to describe briefly the lattice defects owing to metal ion doping and its influence in improving the cathode performance of the olivine phosphates. This gives a new approach in this field.