摘要
为有效抑制尖晶石锰酸锂的Jahn-Teller效应,改善其在高倍率充放电循环中容量衰减快的问题,采取熔盐燃烧法和不同焙烧温度成功制得LiNi_(0.05)Mn_(1.95)O_(4)样品。实验结果表明,Ni掺杂和不同的焙烧温度没有改变LiMn_(2)O_(4)的晶体结构,随焙烧温度升高,结晶性增加,颗粒尺寸增大,逐渐由纳米级变为亚微米级。在优化焙烧温度650℃下制备的样品电化学性能最优,5C下初始放电比容量及500次循环后容量保持率分别为100.8 mA·h/g和80.0%,更高倍率(10C)下500次循环容量仅衰减7.5%。动力学性能测试结果表明,其具有较大锂离子扩散系数(3.26×10^(-16)cm^(2)/s)和较小表观活化能(25.67 kJ/mol)。Ni掺杂和不同的焙烧温度抑制了LiMn_(2)O_(4)材料的Jahn-Teller效应,提高了材料的倍率性能和循环寿命。
To effectively suppress Jahn-Teller effect of spinel lithium manganate and improve the problem of rapid capacity decay during high⁃rate charge discharge cycles,the LiNi_(0.05)Mn_(1.95)O_(4)samples were successfully prepared by using a molten salt combustion method and different calcination temperatures.The experiment results demonstrated that the crystal struc⁃ture of LiMn_(2)O_(4)did not change under Ni-doping and different calcination temperatures.With the rise of calcination tempera⁃ture,the crystallinity and particle size of the samples were increased continuously.Besides,the particle sizes were gradually increased from nanoscales to submicron scales.The optimal calcination temperature of 650℃delivered excellent electro⁃chemical performance.The initial discharge specific capacity at 5C and the capacity retention rate after 500 cycles were 100.8 mA·h/g and 80.0%,respectively.At a higher rate of 10C,the capacity of 500 cycles only attenuated by 7.5%.The dy⁃namic performance test results indicated that it had a large lithium⁃ion diffusion coefficient of 3.26×10^(-16) cm^(2)/s and a smaller apparent activation energy of 25.67 kJ/mol.Ni doping and different calcination temperatures inhibited the Jahn⁃Teller effect of LiMn_(2)O_(4)materials,thereby promoted the rate performance and cycle life of LiMn_(2)O_(4)materials.
作者
钱志慧
朱琴
马姣
郭昱娇
向明武
郭俊明
QIAN Zhihui;ZHU Qin;MA Jiao;GUO Yujiao;XIANG Mingwu;GUO Junming(Key Laboratory of Green-Chemistry Materials in University of Yunnan Province,School of Chemistry and Environment,Yunnan Minzu University,Kunming 650500,China;Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China)
出处
《无机盐工业》
CAS
CSCD
北大核心
2024年第4期50-56,84,共8页
Inorganic Chemicals Industry
基金
国家自然科学基金项目(51972282,U1602273)。
作者简介
钱志慧(1999-),女,硕士,研究方向为锂离子电池正极材料,E-mail:1138562350@qq.com;通讯作者:郭昱娇,女,高级工程师,E-mail:guoyujiao1988@163.com;通讯作者:郭俊明,男,教授,硕士生导师,E-mail:guojunming@tsinghua.org.cn。
