氧化淀粉为碳源冷冻干燥法制备LiFePO_4/C的研究

Study on performance of the LiFePO_4/C prepared by freeze drying method using oxidized starch as carbon source

以氧化淀粉为碳前驱体和分散剂,采用冷冻干燥法制备LiFePO4/C正极材料,利用XRD、SEM、恒流充放电等手段对LiFePO4/C复合正极材料的物相结构、表观形貌及材料的电化学性能进行研究。结果表明:冷冻干燥法可以使原料变成粉末,同时不破坏其均匀的混合状态;以氧化淀粉为碳源,碳含量为7.07%,在700℃高温下煅烧12h合成的材料具有完整的晶型结构,颗粒大小均一,首次放电比容量达到l65mAh/g,接近理论放电比容量。1C倍率下,50次循环后的容量衰减仅为0.20%,5C倍率下,50次循环后的容量衰减为1.39%,电化学性能优异。

The LiFePO4/C cathode materials was prepared by freeze drying method using oxidized starch as carbon source and dispersant, The structure, apparent morphology, electronic conductivity were characterized by means of XRD, SEM, electrochemical techniques. The optimized process conditions were： oxidized starch as carbon source, carbon content of 7.07%, calcinations temperature is 700 ℃, calcinations time is 12 h. The sample which was synthesized by the optimized technology conditions has a complete crystal structure, size of the particle uniformity, the first discharge capacity was 165 mAh/g, close to the theoretical discharge capacity. After 50 cycles at 1 C rate, the capacity fade is only 0.20%, and 50 cycles at 5 C rate,the capacity fade is only 1.39%.1t shows excellent electrochemical performance.