Preparation and characterization of Co²⁺ doped graphene/LiFePO₄ composite cathode materials for lithium battery

In order to obtain lithium ion battery cathode materials with high specific capacity, fast charging and discharging rate and excellent cycle performance, Co²⁺ doped graphene/LiFePO₄ composite cathode materials for lithium battery (graphene/LiCo_0.03Fe_0.97PO₄) were synthesized by using a sol-gel in-situ carbothermal reduction treatment. The structure and morphology characterization results show that graphene/LiCo_0.03Fe_0.97PO₄ composites form 3D conducting network structure. The particles grow homogeneously in graphene sheets with the diameters of about 200 nm. The electrochemical test results show that graphene/LiCo_0.03Fe_0.97PO₄ composites exhibit high reversible specific capacity and superior cycle rate performance with the first discharge specific capacity of 159 mA·h·g^-1 at 0.1 C (2.0-4.0 V charge-discharge) and 74 mA·h·g^-1 at 10.0 C of the first discharge. The specific capacity retention is 99.7% after 100 cycles at 0.5 C. The enhanced electrochemical property of graphene/LiCo_0.03Fe_0.97PO₄ composites is attributed to the synergistic effect of Co²⁺ doping and graphene-modification.