Study On Solid-Phase Synthesis Of LiFePO₄/C Cathode Materials

Olivine-structured LiFePO4 is considered as a promising cathode material for lithium-ion batteries, due to its advantages such as environmentally friendliness,abundant raw materials, inexpensive price and high safety.The paper for the actual industrial production,solid phase synthesis method,using different performance of the synthesized LiFePO4/C cathode material, and material synthesis and material properties were studied..LiFePO4/C cathode material is synthesized by method of high temperature Solid-phase synthesis, taking ferric oxide and lithium carbonate and sucrose as raw materials. The effects of Doped carbon,synthesis temperature and reaction time on cathode materials and electrochemical performance were investigated. The addition of carbon effectively controls the size of particle in the process of LiFePO4 synthesized and improves the electrochemical performance of synthetic materials. The optimum synthetic process condition is obtained,the amount of carbon is 10%,the material was synthesized at 720℃for 12h. The discharge capacity of LiFePO4/C is 143.9mAh/g at O.2Crate and 143 mAh/g mAh/g at O.5C rate,and the cycle performance is better.LiFePO4/C cathode material is synthesized taking ferric oxide and lithium dihydrogen phosphate as raw materials. The influence level of the electrochemical performance is obtained by orthogonal experimental. The biggest is lithium ion ratio, secondly is the quantity of additives, and then synthesize temperature and synthesized time. The influences of the various synthetic factors for material performance are studied by parallel experiment. The optimum synthetic process is that lithium ion ratio is 1.005, the ten percent of carbon,700℃and 10h. The capacity of the material is 152.1 mAh/g at 0.1 C rate.The high performance spherical LiFePO4/C cathode material using iron phosphate and lithium carbonate and Lithium hydroxide is synthesized by the wet ball milling process and spray drying granulation technology. Sizing agent after 3 hours ball-milling has smaller size and better particle size distribution. The materials synthesized by the two Lithium raw materials are both better spherical feature and the electrochemical performance. The capacity of the material synthesized by LiCO3 and LiOH-H2O is 151.5mAh/g and 146.5mAh/g.