糖类作为碳源对LiFePO_4/C正极材料性能的影响

Effects of glucide as carbon source on the performance of LiFePO_4/C cathode material

采用固相反应法在惰性气氛下合成了橄榄石型LiFePO4/C正极材料,采用X射线衍射光谱法(XRD),扫描电子显微镜法(SEM)和电化学手段对目标材料进行了结构表征和性能测试。考察了葡萄糖和蔗糖作为碳源对LiFePO4/C正极材料性能的影响。结果表明,以葡萄糖作为碳源的正极材料具有优良的电化学性能,首次放电比容量达136.3mAh/g,远远高于纯的LiFePO4正极材料,随着循环次数的增加,材料的放电比容量逐渐增加,然后趋于稳定。循环30次后,比容量为139.6mAh/g。

Olivine LiFePO4/C cathode material was synthesized by a solid state method in an inert atmosphere. The crystal stucture and electrochemical performance were characterized by XRD, SEM and electrochemical performance test. The effects of dextrose and sucrose as carbon source on the performance of LiFePO4/C cathode material were investigated and the causes were also analyzed. The results demonstrate that the composite material carbon-doped by dextrose has the most excellent electrochemical performance, The initial discharge capacity of the sample as a lithium secondary battery was achieved to 136.3 mAh/g at 0.1 C （corresponding to 17 mA/g）, larger than that of the sample without carbon-doped. The discharge capacity of the material increased and then became stable with the increasing of the circles. After 30 cycles, the capacity reached 139.6 mAh/g.