(湘潭大学 化学学院,湘潭 411105)
摘 要: 通过溶胶-凝胶法合成了含铝富锂正极材料xLi2MnO3·(1-x)LiNi0.8Co0.15Al0.05O2,探讨了化学组分(x=0.5,0.6,0.7,摩尔分数)和煅烧温度(850,900,950 ℃)对材料形貌、结构和性能的影响。采用XRD、SEM和电池充放电测试仪对材料进行物理表征和电性能测试。结果表明:所制备的材料具有典型的α-NaFeO2层状结构。当x=0.6、煅烧温度为900 ℃时,所合成的材料具有较好的形貌和优良的电化学性能;在2.0~4.6 V、0.1C充放电条件下,0.6Li2MnO3·0.4LiNi0.8Co0.15Al0.05O2的首次放电比容量可达229.9 mA?h/g,且首次库仑效率为80.0 %;在0.5C倍率下循环100次后,其放电比容量仍为192.7 mA?h/g,容量保持率达83.8 %,显示了优良的循环性能。此外,材料显示了良好的倍率性能,在2.0C倍率下,其放电比容量仍为173.1 mA?h/g。
关键字: 锂离子电池;含铝富锂正极材料;溶胶-凝胶法;电化学性能
(School of Chemistry, Xiangtan University, Xiangtan 411105, China)
Abstract:Al-doped Li-rich layered xLi2MnO3·(1-x)LiNi0.8Co0.15Al0.05O2 cathode materials were synthesized via sol-gel method, and the influence of chemical component (x=0.5, 0.6, 0.7, mole fraction) and calcination temperature (850, 900 and 950 ℃) on the morphology, structure and performance of the as-prepared materials were discussed. The physical characterization and electrochemical performance test of the as-prepared materials were conducted by means of XRD, SEM and electrochemical measurements. The results demonstrate that the prepared material has a typical α-NaFeO2 layered structure, and the xLi2MnO3·(1-x)LiNi0.8Co0.15Al0.05O2 exhibits the optimal electrochemical performance when the Li content x is equals to 0.6 and sintering temperature at 900 ℃. The resultant 0.6Li2MnO3·0.4LiNi0.8Co0.15Al0.05O2 sample shows an high initial discharge capacity of 229.9 mA?h/g and coulomb efficiency of 80.0% for the first time when cycled in the voltage range of 2.0~4.6 V at 0.1C. In addition, the material exhibits good cycling stability with capacity retention of 83.8 % after 100 cycles at 0.5C. Furthermore, the material also shows good rate capability, delivering high discharge capacity of 173.1 mA?h/g at 2.0C.
Key words: lithium-ion battery; Al-doped Li-rich cathode material; sol-gel method; electrochemical performance