Various amounts of Ni dopant were successfully incorporated into LiFe_0.6Co_0.2Mn_0.2PO₄ via a facile chemical route. The influence of nickel doping on the structural, microstructural, and electrochemical properties was examined. Crystallization of an olivine structure exhibited the successful substitution of Ni instead of Fe, expanding the lattice parameters and inducing lattice microstrains. The specific surface area first increased from 46 to 64m² g⁻¹ and then decreased to 40 m² g⁻¹ by Ni doping. Cyclic voltammetry and galvanostatic charge/discharge techniques revealed redox peaks and voltage plateaus associated with the Co, Mn, and Ni dopants. The doped material (LiFe_0.575Co_0.2Mn_0.2Ni_0.025PO₄) exhibited higher values of specific capacity at all current rates (0.1C to 20C), with a rate capability of 16% and a high capacity retention of 93.8% for 3000 charge/discharge cycles at 10C.