Zn-Al共掺杂和形貌调控制备LiMn2O4正极材料及其电化学性能
Preparation and electrochemical properties of LiMn2O4 cathode by Zn-Al co-doping and morphology control
朱琴 1马姣 1钱志慧 1李萌 1郭昱娇 2郭俊明1
作者信息
- 1. 云南民族大学 化学与环境学院 云南省高校绿色化学材料重点实验室,云南 昆明 650500
- 2. 昆明市生态环境局五华分局 生态环境监测站,云南 昆明 650031
- 折叠
摘要
采用固相燃烧法在不同焙烧温度(600、650、700和750℃)下制备了LiZn0.05Al0.03Mn1.92O4 正极材料,采用XRD、SEM、XPS对其进行了表征,通过循环伏安(CV)和电化学阻抗(EIS)测试了其电化学性能.结果表明,Zn-Al共掺杂和焙烧温度未改变LiMn2O4的晶体结构,正极材料的结晶性随焙烧温度(<750℃)的升高而增加,650℃及以上时形成了较多包含高暴露(111)晶面、小面积(110)、(100)晶面的截断八面体形貌晶粒,但 750℃时正极材料发生部分分解.焙烧温度 650℃的样品(LZAMO-650)表现出最佳的电化学性能,在5 C和10 C倍率下,初始放电比容量分别为101.3、99.9 mA·h/g,循环1000圈后容量保持率分别为81.5%、74.3%;LZAMO-650样品极化作用较小,有较好的循环可逆性,具有较低的电荷转移阻抗(Rct=132.14 Ω)和较大的锂离子扩散系数(DLi+=3.65×10-16 cm2/s).Zn-Al 共掺杂和形貌调控改性 LiMn2O4 正极材料有效抑制了Jahn-Teller效应,形成的截断八面体颗粒形貌降低了Mn的溶解,同时提供了更多的Li+迁移三维通道,从而改善了材料的电化学性能.
Abstract
LiZn0.05Al0.03Mn1.92O4 cathode material,synthesized from solid-state combustion at different calcination temperatures(600,650,700 and 750℃),was characterized by XRD,SEM and XPS,and tested by cyclic voltammetry(CV)and electrochemical impedance(EIS)for evaluation on its electrochemical performance.The results showed that Zn-Al co-doping and calcination temperature did not change the crystal structure of LiMn2O4,while the crystallinity increased with the increase of calcination temperature.More truncated octahedral grains containing high exposure(111),small area(110)and(100)crystal faces were formed at 650℃and higher but partial decomposition occured at 750℃.The sample prepared at 650℃(LZAMO-650)exhibited the best electrochemical performance,with the initial discharge specific capacity of 101.3 and 99.9 mA·h/g and the capacity retention after 1000 cycles of 81.5%and 74.3%at 5 C and 10 C respectively.The LZAMO-650 sample had a relatively small polarization effect and good cyclic reversibility,with a lower charge transfer impedance(Rct=132.14 Ω)and a larger lithium ion diffusion coefficient(DLi+=3.65×10-16 cm2/s).The Zn-Al co-doping and morphology control modified LiMn2O4 cathode material could effectively inhibit Jahn-Teller effect,resulting in truncated octahedral particle morphology,which reduced Mn dissolution and provided more Li+migration three-dimensional channels,thus improving the electrochemical performance of the material.
关键词
固相燃烧法/尖晶石LiMn2O4/Zn-Al共掺/形貌调控/焙烧温度/Jahn-Teller效应/Mn溶解/功能材料Key words
solid-state combustion method/spinel LiMn2O4/Zn-Al co-doping/morphology control/calcination temperature/Jahn-Teller effect/Mn dissolution/functional materials引用本文复制引用
基金项目
国家自然科学基金(51972282)
国家自然科学基金(U1602273)
出版年
2024
NETL
NSTL
万方数据