The Preparation and Electrochemical Performance of Olivine Cathode Materials Based on LiMn₁/₃Fe₁/₃Co₁/₃PO₄/C

Solid solution LiMn₁/₃Fe₃Co₁/₃₃PO₄/C ternary materials were prepared by sol-gel method with glycine or citric acid as chelating agents. SEM images indicate that the particles are well distributed with regular morphologies, and the particle sizes are around 300 nm for both samples. The cyclic voltammetry (CV) and charge-discharge curves show that the reversibility of Mn²+/Mn3+ couple is improved apparently. The redox potential corresponding to Fe²⁺/Fe³⁺ couple has been increased which is beneficial to the energy density, and the redox potential related to Co²⁺/Co³⁺ couple has been declined which could accelerate dynamics of intercalation/deintercalation and make the electrochemical reaction more smoothly. The obtained LiMn₁/₃Fe₁/₃Co₁/₃3PO₄/C materials with glycine as chelating agent deliver a capacity of 151.5, 142.6, 122.8, 97.9 mAh g⁻¹ at 0.05 °C, 0.1 C, 0.5 C and 1 C, respectively. And the obtained material with citric acid as chelating agent delivers a capacity of 150.8, 135.0, 111.5, 85.2 mAh g⁻¹, respectively, at the same rates.