高温固相法合成Li0.98M0.02Fe0.99Mg0.01PO4/C及其电化学性能

摘要

通过高温固相法合成以Fe2O3为铁源,Li2CO3为锂源,柠檬酸为碳源的Li0.98M0.02Fe0.99Mgg0.01PO4/C(M=Al,Ti,V)锂离子电池正极材料,利用了X射线衍射光谱法(XRD)、循环伏安(CV)、电化学阻抗谱(EIS)和恒流充放电等实验方法研究了在铁位固定掺杂摩尔分数为1％的Mg的情况下,变换锂位掺杂金属对产物结构和电化学性能的影响.结果表明,少量金属掺杂后的产物Li0.98M0.02Fe0.99Mg0.01PO4/C其充放电容量和循环性能都比未掺杂的纯相要高.在室温下,Li0.99Al0.02Fe0.99Mg0.01PO4/C材料以0.1倍率放电时,首次比容量达到156 mAh/g,循环几次后达到160.2 mAh/g,循环性能良好,晶胞系数c/a的值与其他掺杂材料相比较高,结晶度好.%Lithium-ion battery cathode material Li0.98M0.02Fe0.99Mg0.01PO4/C (M=Al, Ti, V) was synthesized by high temperature solid state method with Fe2O3 as iron source, Li2CO3 as lithium and citrate -as carbon source. The structure and electrochemical properties were studied by X-ray diffraction spectroscopy (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and constant current charge-discharge experiments. The electrochemical properties of lithium-ion battery were studied with transformation of lithium-bit product of doping metal when iron-bit fixed molar fraction of 1% of the case of Mg. The results show that small amounts of metal doping do not affect the electrochemical performance of LiFePO4, but improve its electrochemical performance. The results analysis shows that, at room temperature the initial specific capacity of Li0.98M0.02Fe0.99Mg0.01PO4/C materials is 156 mAh/g at 0.1 C discharge rate, and after 8 cycles it up to 162.7 mAh/g with good cycle performance, and the cell factor of c/a is greater than other materials with good crystallinety.