Synthesis And Electrochemical Study Of LiFePO₄/C/RGO As Cathode Materials For Lithium-ion Batteries

From the consideration of power density, cycle, price, cost and safety, olivine-typeLiFePO4has considered as a promising cathode material for power lithium-ionbatteries due to its advantages of being naturally abundant, inexpensive, nontoxic,high capacity of170mAh/g, flat voltage plateau around3.45V, safety, and goodcycling stability. However, its rate performance of pristine material is restricted bypoor electric conductivity and slow Li+diffusion. This thesis put effort intonano-LiFePO4, and modification of nano-LiFePO4materials were mainly by addgraphene to enhance electric conductivity.1、A novel, economic and scalable method is proposed in this context using animpinging jet reactor to continuously precipiate FePO4by enhance supersaturation.Then, LiFePO4/C/RGO composites were synthesized via an aqueous solution-evaporation route with FePO4, LiOH·H2O, GO and citric acid. Containing150nmprimary particles, the LiFePO4/C/RGO composite added GO by7%(by weight)exhibited the best electrochemical performance. Obtained core-shell cathodecomposite adhere to crepe-like texture graphene, in this way, building a conductivenetwork between particles.2、The synthesized graphene is good dispersibility by electrostatic force, then,LiFePO4/C/RGO composites were synthesized via mechanochemical activation routewith FeC2O4·2H2O, NH4H2PO4, Li2CO3and graphene, citric acid. the composite with3wt.%graphene content exhibited the best electrochemical performance.