熔盐燃烧法制备Ni-Cr共掺LiMn_(2)O_(4)正极材料及电化学性能研究  

Preparation and electrochemical properties of Ni-Cr co-doped LiMn_(2)O_(4)cathode material by molten salt combustion method

作　　者：郭昱娇 罗学英 林杰 宁平[1] 郭俊明 Guo Yujiao;Luo Xueying;Lin Jie;Ning Ping;Guo Junming(Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650500;Eco-environment Monitoring Station of Wuhua Branch,Kunming Eco-environment Bureau,Kunming 650031;School of Chemistry and Environment,Yunnan Minzu University,Kunming 650500)

机构地区：[1]昆明理工大学环境科学与工程学院,昆明650500 [2]昆明市生态环境局五华分局生态环境监测站,昆明650031 [3]云南民族大学化学与环境学院,昆明650500

出　　处：《化工新型材料》2023年第3期166-172,共7页New Chemical Materials

基　　金：国家自然科学基金(51972282)。

摘　　要：采用熔盐燃烧法和不同焙烧温度处理制备了一系列尖晶石型LiNi_(0.05)Cr_(0.05)Mn_(1.90)O_(4)(LNCMO)正极材料,研究了焙烧温度对LNCMO的结构、微观结构形貌、电化学性能和动力学性能等的影响。结果表明,所制备样品都归属于LiMn_(2)O_(4)立方晶系Fd3m空间群,随焙烧温度升高,样品颗粒逐渐增大,其中550℃制备的为纳米级颗粒,其余为亚微米级。其中600℃焙烧温度制备的LNCMO样品展现出最佳的电化学性能,在5C倍率下,其首次放电比容量为109.1mAh/g,500次循环容量保持率为75.7%。电流密度增大到15C和30C时,经800次循环后该样品仍有64.4%和60.6%的容量保持率,并且其具有最大的Li+扩散系数(6.31×10^(-16) cm^(2)/s)和最小的电荷转移电阻(89.0Ω)。Ni-Cr共掺有效抑制了Jahn-Teller效应,适宜的二次焙烧温度有利于稳定材料的晶体结构,从而提高其倍率性能和循环性能。A series of spinel LiNi_(0.05)Cr_(0.05)Mn_(1.90)O_(4)(LNCMO-x)cathode materials were prepared by molten-salt combustion method and different calcination temperature treatments.The effects of calcination temperature on the structure,microstructure morphology,electrochemical performance and dynamic performance of LNCMO were studied.The results showed that all the prepared samples belonged to the Fd3mspace group of the LiMn_(2)O_(4)cubic crystal system.With the increase of the calcination temperature,the sample particles gradually increased.Among them,the particles prepared at 550℃were nano-sized particles,and the rest were sub-micron-sized particles.The LNCMO sample prepared at 600℃exhibited the best electrochemical performance.At 5C,its first discharge specific capacity was 109.1mAh/g and its capacity retention rate after 500cycles was 75.7%.When the current density was increased to 15C and 30C,the sample still had a capacity retention rate of 64.4%and 60.6%after 800cycles,and it had the largest Li+diffusion coefficient(6.31×10^(-16) cm^(2)/s)and the smallest the charge transfer resistance(89.0Ω).Ni-Cr co-doping effectively suppressed the Jahn-Teller effect,and an appropriate secondary calcination temperature was conducive to stabilize the crystal structure of the material,thereby improving its rate performance and cycle performance.

关 键 词：LiMn_(2)O_(4) Ni-Cr共掺杂 熔盐燃烧法 焙烧温度 正极材料 JAHN-TELLER效应 

分 类 号：TM912[电气工程—电力电子与电力传动]