LiFePO_4锂电池正极材料的Li_(0.5)La_(0.5)TiO_3包覆改性

Li_(0.5)La_(0.5)TiO_3 Coating for LiFePO_4 Cathode Material of Li-ion Battery

研究了以快离子导体Li_(0.5)La_(0.5)TiO_3(LLTO)包覆的LiFePO_4正极材料的锂离子电池的电化学性能。采用溶剂热法制备锂电池正极材料LiFePO_4,再采用溶胶凝胶法制备的LLTO粉体对LiFePO_4进行包覆,包覆量为LiFePO_4质量分数的1%~4%.通过进行充放电测试、交流阻抗测试及循环伏安测试,研究了不同包覆量对电池的充放电比容量、循环性能及可逆性的影响。发现当LLTO含量为3 wt%,2 C、5 C时,充放电时相对于没有包覆LLTO的电池正极材料的比容量分别提高29.7%、31.6%,30次循环之后,容量损失率减小4.13%,循环伏安曲线上氧化还原峰之间的电位差仅为0.117 V,以3 wt%的LLTO包覆改性LiFePO_4显著提高了电池的电化学性能。

The cathode material LiFePO4 was coated with fast ionic conductor Li0.5La0.5TiO3（LLTO）to investigate the electrochemical properties of Li-ion battery. LiFePO4 was synthesized via solvothermal route,and LLTO powder was synthesized via sol-gel route,then LiFePO4 was coated by LLTO with the LLTO proportion of 1 wt% ~ 4 wt%.The effects of LLTO coating proportion on discharge specific capacity,cycle performance and reversibility were studied by charge/discharge test,AC impedance test and cyclic voltammetry test. The results indicate that when LLTO coating proportion is 3 wt%,the specific capacity increases by 29. 7 % in the current rate of 2 C and increases by 31. 6 % in the current rate of 5 C,the capacity loss rate after 30 charge/discharge cycles decreases by 4.13%,and the potential difference between redox peaks in cyclic voltammetry curve is only 0. 117 V. LLTO coating LiFePO4 with proportion of 3 wt% significantly improves electrochemical properties of Li-ion battery.