负极材料Li_4Ti_5O_(12)的改性及其电化学性能的研究

Modification and electrochemical performance of Li_4Ti_5O_(12) as anode material

以CH3COOLi·2 H2O和Ti(OC4H9)4为原料,C6H15NO3为络合剂,CH3CH2OH为溶剂,采用溶胶-凝胶法制备Li4Ti5O12材料,并且复合掺杂Mg、Mn、Ni、Co四种金属。采用X射线衍射(XRD)、扫描电镜、电化学阻抗(EIS)分析研究了材料的结构、形貌和电化学性能。结果表明:掺杂Mn、Mg两种金属的Li4-x MgxTi5-yMnyO12材料,其中x=0.02,y=0.02时所制备的Li3.98Mg0.02Ti4.98Mn0.02O12样品,具有良好的电化学性能。在1～2.5V进行充放电,0.1C时,首次放电容量达到154.7 mAh/g。在0.2C、0.5C、1.0C下循环20次后,稳定在107.2、99.3、73.9 mAh/g。再次进行0.1C充放电时,放电比容量为110.8 mAh/g,容量保持率为75%。掺杂金属改善了Li4Ti5O12材料的导电性,提高了该材料的倍率性能以及循环性能。

Li4Ti5O12 as anode material was prepared by sol-gel method, using CH3COOLi .2 H2O, Ti（ OC4H9）4 as raw materials, C6H15NO3as complexing agent, CH3CH2OH as solvent, doping four different metals of Mg, Mn, Ni, Co. The products were characterized by XRD,SEM, constant current charge and discharge, electrochemical impedance spectrescopy （EIS） to analyze the structure, morphology and electrochemical performance of the products. The results show that, Li4-xMgxTi5-yMnyO12 was doped the metals of Mg, Mn, and when the xis 0.02, yis 0.02, the prepared materials of Li3.90Mg0.02Ti4.98Mn0.02O12 has a good electrochemical performance. When discharge and charge between 1.0-2.5 V, its initial discharge specific capacity is 154.7 mAh/g at the rate 0.1 C. When circling 20 times at 0.2, 0.5, 1.0 C, the specific capacity is respectively stabilized at 107.2, 99.3, 73.9 mAh/g. When discharge and charge at 0.1 C, the discharge specific capacity is 110.8 mAh/g, and the capacity retention is of 75%. The doping metals not only improve the conductivity of Li4Ti5O12 but also its rate performance and cycle performance.