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通过溶胶-凝胶法并结合热处理工艺制备LiFePO4粉体,采用XRD、SEM及恒电流充放电技术等方法,研究了煅烧时间对LiFePO4粉体结构、形貌及电化学性能的影响。结果表明:以聚丙烯酸(PAA)、硝酸铁、硝酸锂和磷酸二氢铵为原料,在一定温度下合成了稳定的溶胶和凝胶,经650℃煅烧得到LiFePO4粉体。随着煅烧时间的延长,粉体颗粒逐渐增大,晶型趋于完整;煅烧16 h获得的LiFePO4颗粒大小均匀,晶型完整且没有明显团聚现象。1C倍率下首次放比电容量达到140 mAh/g,经100次循环后仍高于130 mAh/g,容量保持率高达93%,表现出良好的充放电稳定性。
LiFePO4 powder was prepared by sol-gel method combined with heat treatment. The effects of calcination time on the structure, morphology and electrochemical performance of LiFePO4 powder were investigated by XRD, SEM and galvanostatic charge-discharge technique. The results showed that LiFePO4 powder was synthesized by polyacrylic acid (PAA), ferric nitrate, lithium nitrate and ammonium dihydrogen phosphate at a certain temperature. With the prolongation of calcination time, the size of the powder particles gradually increases and the crystal form tends to be complete. The size of LiFePO4 particles obtained after calcination for 16 h is uniform and the crystal form is complete without obvious agglomeration. The initial discharge capacity of 140 mAh / g at 1C rate is higher than 130 mAh / g after 100 cycles, and the capacity retention rate is as high as 93%, showing good charge-discharge stability.