锌掺杂对LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2正极材料结构和电化学性能的影响

Effect of Zinc Doping on Structure and Electrochemical Performance of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 Cathode Material

采用草酸盐共沉淀法制备出锌掺杂的锂离子电池正极材料,结合X射线衍射(XRD)、扫描电镜(SEM)、EDS能谱(EDS mapping)、恒电流充放电和电化学阻抗(EIS)测试,研究Zn2+掺杂对材料晶体结构、形貌及电化学性能的影响。实验结果表明,Zn2+掺杂可抑制高镍材料中的离子混排,形成多孔结构,缩短Li+的扩散路径,从而改善材料的倍率和循环性能。在2.7~4.3 V电压范围内,10 C倍率下Li(Ni_(0.6)Co_(0.2)Mn_(0.2))0.99Zn0.01O2表现出87.8 m Ah·g-1的放电比容量,比LiNi_(0.6)Co_(0.2)Mn_(0.2)O2提高了37.0%,1 C倍率下循环100圈后,Li(Ni_(0.6)Co_(0.2)Mn_(0.2))0.99Zn0.01O2的容量保持率为84.7%,比未掺杂的材料提高了12%。EIS测试结果则进一步验证锌掺杂有效降低了材料的电荷传质阻抗。

By the oxalate co-precipitation method, a zinc-doped cathode material for lithium-ion battery was prepared. X-ray diffraction（XRD）, scanning electron microscopy（SEM）, EDS mapping, galvanostatic charge-discharge and electrochemical impedance spectroscopy（EIS） tests were performed to investigate the effect of Zn2＋ doping on the structure, morphology, and electrochemical performance of the material. The results show that Zn2＋ doping can inhibit the cation mixing, form a porous structure, shorten the diffusion path of Li＋ and improve the rate and cycling performance of the material. In the voltage range of 2.7-4.3 V, Li（Ni（0.6）Co（0.2）Mn（0.2））0.99 Zn0.01 O2 shows a discharge specific capacity of 87.8 m Ah·g-1 at 10 C, which is 37.0 % higher than that of Li Ni（0.6）Co（0.2）Mn（0.2） O2. After 100 cycles at 1 C, the capacity retention of Li（Ni（0.6）Co（0.2）Mn（0.2））0.99 Zn0.01 O2 is 84.7 %, which is 12 % higher than that of the undoped material. EIS test results further verify that zinc doping effectively reduces the charge transfer resistance of the material.