络合剂对溶胶-凝胶法制备LiNi_(0.80)Co_(0.15)Al_(0.05)O_2正极材料电化学性能影响

Effect of Complexing Agent on Electrochemical Performance of LiNi_(0.80)Co_(0.15)Al_(0.05)O_2 Cathode Materials Prepared by Sol-gel Method

以马来酸、甘氨酸或柠檬酸作为络合剂,采用溶胶-凝胶法制备锂离子电池Li Ni0.80Co0.15Al0.05O_2正极材料,对比了络合剂种类对样品电化学性能的影响。结果表明:采用不同络合剂制备的样品都具有层状结构,以柠檬酸为络合剂制备的样品存在较多的八面体单晶体。电化学分析显示,以马来酸为络合剂制备的样品具有最佳的充放电和循环性能:0.2C下首次放电容量为176 m A·h/g,30次循环后容量保持率为97.3%;1C下首次放电容量为162 m A·h/g,30次循环后容量保持率为92.3%。根据循环伏安曲线得到的锂离子的扩散系数表明,采用马来酸为络合剂制备的样品具有最大的扩散系数。

LiNi0.80Co0.15Al0.05O2 （NCA） cathode materials were prepared by a sol-gel method using maleic acid, glycine or citric acid as complexing agent. The microstructure and morphology of the cathode materials were characterized by X-ray diffraction and scanning electron microscopy（SEM）. The electrochemical properties, i.e., galvanostatic charge-discharge capacity, cyclic voltammetry, and cycling performance were determined. XRD analysis demonstrates that all the samples prepared using different complexing agents present a hexagonal α-NaFeO2 layered structure with the space group R3m. SEM observation reveals that, the sample prepared using citrate has the more octahedral single crystals. For the NCA cathode material prepared using maleic acid, its initial discharge capacities of are 176 mA.h/g at 0.2C and 162 mA·h/g at 1C, respectively; after 30 cycles, the capacity retention rate is 97.3% for 0.2C and 92.3% for 1C, respectively.