钛酸酯偶联剂表面处理对LiMn_(2)O_(4)结构及性能的影响  

Effect of Surface Treatment with Titanate Coupling Agent on Structure and Performance of LiMn_(2)O_(4)

作　　者：蔡海洋 李振京 范广新[1] 孟德轩 刘超帅 CAI Haiyang;LI Zhenjing;FAN Guangxin;MENG Dexuan;LIU Chaoshuai(School of Materials Science and Engineering,Henan Polytechnic University,Jiaozuo 454000,Henan,China;LongBai Group Co.,Ltd.,Jiaozuo 454000,Henan,China)

机构地区：[1]河南理工大学材料科学与工程学院,河南焦作454000 [2]龙佰集团股份有限公司,河南焦作454000

出　　处：《矿冶工程》2024年第4期18-23,30,共7页Mining and Metallurgical Engineering

基　　金：国家自然科学基金重点项目(U1804135,51671080);河南省科技创新人才计划(194200510019)。

摘　　要：通过加热分解钛酸酯偶联剂在LiMn_(2)O_(4)表面包覆TiO_(2),研究包覆处理对LiMn_(2)O_(4)材料结构、电化学性能及在循环过程中材料结构的影响。结果表明:550℃下加热分解钛酸酯偶联剂,可使TiO_(2)均匀包覆在材料表面;表面包覆不改变LiMn_(2)O_(4)的晶体结构,但能明显提升其电化学性能,特别是高温倍率性能和循环性能;包覆TiO_(2)后的LiMn_(2)O_(4)材料在55℃、5C下比容量为75.34 mAh/g,高于原始材料的比容量(43.05 mAh/g);经150次循环后,未包覆TiO_(2)的材料容量保持率为62.85%,包覆TiO_(2)后的材料容量保持率提高至77.27%。表面处理后LiMn_(2)O_(4)电化学性能提升的原因是TiO_(2)包覆层减少了正极材料中Mn的溶解,抑制了循环过程中的晶体结构变化,降低了电极极化和电荷转移阻抗,提高了材料的充放电可逆性及Li+的扩散能力。TiO_(2)was coated on the surface of LiMn_(2)O_(4)by thermal decomposition of titanate coupling agent,and the effects of coating treatment on the structure and electrochemical performance of LiMn_(2)O_(4),as well as material structure in the cycling were all explored.The results show that TiO_(2)can be uniformly coated on the surface of the LiMn_(2)O_(4)by thermal decomposition of titanate coupling agent at 550℃.Surface coating does not change the crystal structure of LiMn_(2)O_(4),but obviously improves its electrochemical performance,especially high temperature rate performance and cycle performance.At 55℃,LiMn_(2)O_(4)with TiO_(2)coating delivers a specific capacity of 75.34 mAh/g at 5C,which is higher than that without coating(43.05 mAh/g).After 150 cycles,the capacity retention rate of the material with TiO_(2)coating and without coating is 77.27%and 62.85%,respectively.The improvement of electrochemical performance is attributed to reduction of Mn dissolution in the cathode material by TiO_(2)coating,which thus inhibits the change of crystal structure during cycling process,reduces the electrode polarization and charge transfer impedance,as well as improves the charge-discharge reversibility of the material and the Li+diffusion.

关 键 词：正极材料 LiMn_(2)O_(4) TiO_(2) 钛酸酯偶联剂 表面包覆 改性 电化学性能 

分 类 号：TQ152[化学工程—电化学工业]