Ni-F共掺纳米LiMn_(2)O_(4)正极材料及电化学性能  

Electrochemical Characterization of Ni-F Co-doped Nano LiMn_(2)O_(4) Cathode Materials

作　　者：陶扬 李燕 郭俊明 向明武 白玮 白红丽 刘晓芳 Tao Yang;Li Yan;Guo Junming;Xiang Mingwu;Bai Wei;Bai Hongli;Liu Xiaofang(School of Chemistry and Environment,National and Local Joint Engineering Research Center for Green Preparation Technology of Bio-based Materials,Key Laboratory of Green Chemical Materials in Universities of Yunnan Province,Yunnan Minzu University,Kunming 650500,China)

机构地区：[1]云南民族大学化学与环境学院生物基材料绿色制备技术国家地方联合工程研究中心云南省高校绿色化学材料重点实验室,云南昆明650500

出　　处：《稀有金属材料与工程》2021年第9期3248-3255,共8页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(U1602273,51972282);云南省教育厅科学研究基金(2020Y0262)。

摘　　要：采用熔盐燃烧合成了Ni-F共掺的纳米LiNi_(0.03)Mn_(1.97)O_(3.95)F_(0.05)(LNMOF)正极材料。结果表明,Ni-F共掺显著提高了材料的倍率性能、循环稳定性及初始比容量,在5、10、15和20 C倍率下,首次放电比容量分别为101.4、92.5、89.4和66.8 mAh∙g^(-1),循环1000次后容量保持率分别为77.9%、70.8%、70.9%和72.9%。循环伏安和电化学阻抗测试结果表明,与LiMn_(2)O_(4)样品相比,LNMOF正极材料有较低的表观活化能24.72 kJ∙mol^(-1)与较大的锂离子扩散系数1.174×10^(-8) cm^(2)∙s^(-1)。对循环前后极片进行XRD分析,发现LNMOF晶体结构基本没有变化。适量的镍和氟共掺杂能够有效抑制Jahn-Teller畸变,稳定晶体结构,在材料的比容量提高的同时,也改善了材料的循环性能。Ni-F co-doped nano LiNi_(0.03)Mn_(1.97)O_(3.95)F_(0.05)(LNMOF)cathode material was synthesized by a molten-salt combustion method.The results show that Ni-F co-doping markedly improves the rate performance,cycling stability and specific capacity of the LNMOF.At the rates of 5,10,15,20 C,LNMOF exhibits an initial discharge capacity of 101.4,92.5,89.4 and 66.8 mAh∙g^(-1),respectively.After 1000 cycles,a capacity retention rates of LNMOF are 77.9%,70.8%,70.9%and 72.9%,respectively.Cyclic voltammetry and electrochemical impedance spectroscopy show that LNMOF cathode material exhibits lower apparent activation energy 24.72 kJ∙mol^(-1) and greater diffusion coefficient of lithium ion 1.174×10^(-8) cm^(2)∙s^(-1),when compared to the LiMn_(2)O_(4) sample.The electrode before and after 1000 cycles were investigated by XRD.It is demonstrated that the crystal structure of the LNMOF sample has hardly changed.Moderate Ni-F co-doping effectively inhibits Jahn-Teller distortion,stabilizes crystal structure and improves the specific capacity and enhances the cycle performance of LiMn_(2)O_(4) cathode materials at the same time.

关 键 词：Ni-F共掺杂 尖晶石型LiMn_(2)O_(4) 熔盐燃烧法 正极材料 JAHN-TELLER畸变 

分 类 号：TM912[电气工程—电力电子与电力传动]