基于聚合反应制备的钛离子掺杂LiFePO4/C复合材料

首先基于聚合反应合成FePO4/PANI前驱体,再以为LiOH·H2O,FePO4/PANI 和 PVA原料制备了LiFePO4正极材料,此外再对其进行碳包覆以及Ti4+掺杂,三种试样分别标记为LiFePO4,LiFePO4/C及LiFe0.96Ti0.02PO4/C.通过XRD、EDS及充放电测试等手段表征了材料的微观结构与电化学性能.实验结果证明:试样的XRD图谱均与标准LiFePO4图谱一致,不存在无定形碳衍射峰.与未掺杂试样LiFePO4/C相比,LiFe0.96Ti0.02PO4/C的电子电导率与其相近,但离子扩散系数有所改善,Ti4+在晶格中均匀分布,因此与其他两试样相比,其电化学性能更好.试样在C/10、C/2、1C、3C及5C倍率下的放电比容量为158.7 mAh·g-1、153.3 mAh·g-1、147.6 mAh·g-1、136.4 mAh·g-1及123.5 mAh·g-1,具有良好的倍率性能与电位稳定性.

Synthesis of Ti Ion Doped LiFePO4/C Composite Material Based on Polymerization Reaction

Firstly, the precursor powder FePO4/PANI was synthesized by polymerization reaction.Then, the cathode material LiFePO4 was synthesized by using LiOH·H2O, FePO4/PANI and PVA as the raw materials.In addition the carbon-coated and Ti4+-doped material were synthesized simultaneously.These three samples were marked as LiFePO4, LiFePO4/C and LiFe0.96Ti0.02PO4/C.Their respective microstructure and characteristics were investigated via XRD, EDS and charge-discharge tests.The XRD patterns agree well with the standard LiFePO4 pattern and without amorphous carbon.Comparing with sample LiFePO4/C, LiFe0.96Ti0.02PO4/C has approximate electronic conductivity and higher Li+ diffusion coefficient.Ti4+ distributes in the lattice evenly.Thus, LiFe0.96Ti0.02PO4/C has better electrochemical performances than the other samples.It's initial discharge capacities are 158.7 mAh·g-1,153.3 mAh·g-1,147.6 mAh·g-1,136.4 mAh·g-1 and 123.5 mAh·g-1 at C/10、C/2、1C、3C and 5C rate respectively.The rate performance and potential stability of LiFe0.96Ti0.02PO4/C are favorable.