苯胺用量对固相法合成LiFePO_4/C电化学性能的影响

Efluence of aniline on electrochemical performance of LiFePO_4/C by solid phase method

通过聚苯胺包覆法制备LiFePO4／C，研究了苯胺用量对LiFePO4／C电化学性能的影响。采用X射线衍射（XRD）测试材料结构并用扫描电镜（SEM）和透射电镜（TEM），观察材料形貌及碳层包覆情况。结果表明：该方法制得的LiFePO4结晶度高并且具有规整的球状结构，粒径在50~80nm之间，碳层厚度约为2．5nm。经电化学性能测试发现：在相同合成工艺下，苯胺用量对合成的LiFePO4／C的电化学性能有很大影响．当苯胺加入量为0．5mL时所得LiFePO4／C（6mmol）的电化学性能最佳，0．2C下首次放电比容量可达161．6mAh·g^-1，5C下放电比容量可达112．2mAh·G^-1～，且在5C下循环300次无明显衰减。

The LiFePO4/C composite electrode material was synthesized by an in-situ polymerization restriction method with polyaniline as the carbon source. The electrochemical performance of LiFePO4 with the difference mass of ani- line was researched. The structure and morphology of the samples were investigated by X--ray diffraction（ XRD）, scanning electron microscopy（ SEM ） and transmission electron microscopy. The results showed that the synthesized LiFePO4/C composite was in pure phase and spherical morphology with the particle sizes in the range of 50 ~ 80 nm. The thickness of the carbon film could be as thin as about 2. 5 nm for the isolated LiFePO4/C particles. It also showed that its electrochemical performances were quite different from the mass of aniline. When 0. 5ml aniline was used to synthesize LiFePO4 （0.03 mol）, the results were best. The initial discharge capacities of LiFePO4/C composite reached 161.6 and 112.2mAh/g at the rate of 0. 2 C and 5 C rates. Remarkably,even after 300 cycles the discharge capacity didn＇t had reduced.