熔盐燃烧制备纳米LiN_(i0.05)Mn_(1.95)O_(4)正极材料及电化学性能研究  

Preparation and electrochemical properties of nano-LiN_(i0.05)Mn_(1.95)O_(4) cathode materials by molten salt combustion

作　　者：马姣 钱志慧 朱琴 白玮 郭昱娇 郭俊明 Ma Jiao;Qian Zhihui;Zhu Qin;Bai Wei;Guo Yujiao;Guo Junming(Key Laboratory of Green Chemical Materials in Yunnan Universities,College of Chemistry and Environment,Yunnan Minzu University,Kunming 650500;Eco-environment Monitoring Station of Wuhua Branch,Kunming Eco-environment Bureau,Kunming 650031)

机构地区：[1]云南民族大学化学与环境学院,云南民族大学云南省高校绿色化学材料重点实验室,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

出　　处：《化工新型材料》2024年第9期136-142,共7页New Chemical Materials

基　　金：国家自然科学基金(51972282和U1602273)。

摘　　要：采用熔盐燃烧法在300℃、400℃、500℃和600℃下燃烧反应1h,然后经650℃焙烧3h,制得4种LiN_(i0.05)Mn_(1.95)O_(4)正极材料。结果表明:所制LiN_(i0.05)Mn_(1.95)O_(4)正极材料的原有立方尖晶石结构均没有被改变,随燃烧反应温度递增,粒径略微增大,由纳米类球形颗粒变为亚微米多面体类球形颗粒。其中,燃烧反应优化温度500℃制备的LiN_(i0.05)Mn_(1.95)O_(4)正极材料为纳米级多面体类球形颗粒,电化学性能优良,在1C下首次放电比容量和100次充放电后容量保持率分别是103.8mAh/g和90.3%,而5C和更高倍率10C时,首次放电比容量分别为98.4mAh/g和88.2mAh/g,分别经500和1000次循环后仍有79.0%和76.1%的容量保持率。该材料具有较小的表观活化能(25.7kJ/mol)及较大的锂离子扩散系数(3.54×10^(-16)cm^(2)/s)。Ni掺杂提高了循环过程中LiMn 2O 4晶体结构稳定性,抑制了Jahn-Teller畸变,适宜的燃烧反应温度可制备纳米级颗粒样品,提升其高倍率容量和电化学性能。Four LiN_(i0.05)Mn_(1.95)O_(4)cathode materials were prepared at 300℃,400℃,500℃and 600℃for 1h,and then calcined at 650℃for 3h by molten salt combustion.The results showed that the original cubic spinel structure of LiN_(i0.05)Mn_(1.95)O_(4)was not changed,and the particle size increased slightly with the increase of combustion reaction temperature,transitioning from nanoscale spherical particles to submicron polyhedral spherical particles.Among them,the LiN_(i0.05)Mn_(1.95)O_(4)cathode material prepared at an optimized combustion temperature of 500℃was nanoscale polyhedral spherical particles with excellent electrochemical performance.At 1C,the first discharge specific capacity and the capacity retention ratio after 100 charge-discharge cycles were 103.8mAh/g and 90.3%,respectively.Furthermore,at 5C and higher rate of 10C,the first discharge specific capacities were 98.4 and 88.2mAh/g,respectively,and the capacity retention ratios were 79.0%and 76.1%after 500 and 1000 cycles,respectively.The material had a small apparent activation energy(25.7kJ/mol)and a large lithium-ion diffusion coefficient(3.54×10^(-16)cm^(2)/s).Ni doping improved the crystal structure stability of LiMn 2O 4 during cycling and inhibited Jahn-Teller distortion.Nanoscale particle samples could be prepared at a suitable combustion reaction temperature,improving the high-rate capacity and electrochemical performance.

关 键 词：LiMn_(2)O_(4) 熔盐燃烧法 镍掺杂 JAHN-TELLER畸变 纳米尺寸 高倍率容量 

分 类 号：TM912[电气工程—电力电子与电力传动]