化工进展 ›› 2021, Vol. 40 ›› Issue (7): 3915-3922.DOI: 10.16085/j.issn.1000-6613.2020-1718

• 材料科学与技术 • 上一篇    下一篇

亚微米LiFe0.05Mn1.95O4正极材料的制备及电化学性能

刘红雷(), 郭俊明(), 向明武, 白玮, 白红丽, 刘晓芳, 段开娇   

  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
  • 收稿日期:2020-08-27 修回日期:2020-11-03 出版日期:2021-07-06 发布日期:2021-07-19
  • 通讯作者: 郭俊明
  • 作者简介:刘红雷(1995—),男,硕士研究生,研究方向为锂离子电池正极材料。E-mail:liuhong_lei@foxmail.com
  • 基金资助:
    国家自然科学基金(51972282)

Synthesis and electrochemical performance of submicron LiFe0.05Mn1.95O4 cathode material

LIU Honglei(), GUO Junming(), XIANG Mingwu, BAI Wei, BAI Hongli, LIU Xiaofang, DUAN Kaijiao   

  1. School of Chemistry and Environment, Yunnan Minzu University, National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, Key Laboratory of Green-chemical Materials in University of Yunnan Province, Kunming 650500, Yunnan, China
  • Received:2020-08-27 Revised:2020-11-03 Online:2021-07-06 Published:2021-07-19
  • Contact: GUO Junming

摘要:

采用固相燃烧法合成了亚微米单晶多面体LiFe0.05Mn1.95O4正极材料。借助XRD、FE-SEM、TEM、XPS和恒电流充放电等手段对样品的结构、形貌、物相组成和电化学性能进行测试。结果表明,Fe掺杂未改变尖晶石型LiMn2O4的立方晶系结构,其{400}和{440}衍射峰相对应的晶面出现显著的择优生长,形成了形貌为{111}、{110}和{100}晶面的单晶去顶角八面体晶粒。LiFe0.05Mn1.95O4正极材料表现出比纯LiMn2O4材料更为优异的电化学性能,在1C和5C时有着114.7mA·h/g、104.7mA·h/g首次放电比容量,10C倍率下经1000次循环后,容量保持率为83.9%。循环伏安与阻抗分析得出掺杂后的样品有着较大的锂离子扩散系数与较小的活化能。对5C倍率循环1000次后Fe掺杂样品的极片分析发现,其晶体结构基本无变化,适量的Fe掺杂能够有效抑制尖晶石型LiMn2O4在充放电循环过程中的Jahn-Teller效应以及Mn的溶解,提升材料的结构稳定性与容量保持率。

关键词: 尖晶石型LiMn2O4, Fe掺杂, 单晶多面体, 亚微米, 正极材料, Mn溶解, 电化学, 动力学

Abstract:

The cathode material of submicron LiFe0.05Mn1.95O4 single crystal was synthesized by a solid state combustion method. The structure, morphology, phase composition and electrochemical performance of the sample were investigated by XRD, FE-SEM, TEM, XPS and galvanostatic charge and discharge. The results showed that, Fe-doping did not change the cubic crystal structure of spinel LiMn2O4, but the crystal surface corresponding to {400} and {440} diffraction peak exhibited a significant selective growth, and the single crystal deciding-angle octahedral grains with the morphologies of {111}, {110} and {100} crystal surface were formed. The LiFe0.05Mn1.95O4 cathode material exhibited better electrochemical performance than the undoped sample of LiMn2O4. The initial specific discharge capacities were 114.7mA·h/g and 104.7mA·h/g at 1C and 5C, respectively. The capacity retention was 83.9% at 10C after 1000 cycles. By analyzing the cyclic voltammogram and electrochemical impedance spectroscopy, we found that the Fe-doped sample possessed large lithium ion diffusion coefficient and low apparent activation energy. The spinel structure of the sample's electrode slice was almost unchanged after 1000 cycles at 5C. Appropriate Fe-doping can effectively inhibit the Jahn-Teller effect and the Mn dissolution of spinel LiMn2O4 in the process of charge and discharge cycles, and hence improve the capacity retention and structural stability of the material.

Key words: spinel LiMn2O4, Fe-doping, single crystal polyhedron, submicron, cathode material, Mn dissolution, electrochemistry, kinetics

中图分类号: 

版权所有 © 《化工进展》编辑部


本系统由北京玛格泰克科技发展有限公司设计开发 技术支持:support@magtech.com.cn