中文摘要：

为提高锂离子电池正极材料LiMn2O4在高温下的循环性能，以Sn（OCH2CH2OCH3）4为原料，采用溶胶一凝胶法在LiMn2O4表面包覆了一层稳定的二氧化锡层．用X射线粉末衍射和扫描电镜对包覆前后LiMn2O4的结构进行了表征．结果表明，二氧化锡包覆层的存在减少了LiMn2O4与电解液的直接接触，有效地抑制了高温下LiMn2O4与电解液的相互作用，减少了锰在电解质中的溶解；经表面修饰处理后，LiMn2O4正极材料的初始容量虽稍有下降，但高温下（60℃）的充放电循环稳定性能得到了显著提高，40次循环后的高温容量衰减由改性前的31％降低到12％，并且电池的自放电速率也显著减小．作为锂离子电池的正极材料，该表面改性材料是众多取代LiCoO2材料中最具竞争力的材料之一，也有望成为锂离子动力电池的正极材料．

英文摘要：

In order to improve electrochemical performance of spinel LiMn2O4 for positive electrode material of lithium ion battery at high temperature （60 ℃）, the stable SnO2 film was coated on the surface of LiMn2O4 positive electrode material by sol-gel method with Sn（OCH2CH2OCH3）4. The structures of the coated and uncoated LiMn2O4 were characterized by XRD and SEM techniques. The results show that the SnO2 layer can reduce the direct contact between LiMn2O4 and electrolyte, and thus effectively restrains the harmful interactions between them at elevated temperature and reduces the dissolving of manganese in electrolyte. Although the initial electric volume of positive electrode material LiMn2O4 decreases slightly after modification, its cycling stability of charge/discharge increases remarkably, in this work, the capacity loss decreases from 31% for pure LiMn2O4 to 12% at 60℃ after 40 times cycling, and the self-discharge rate of the battery is largely reduced. As a cathode material of lithium-ion battery, this modified spinel is one of the most competitive substitutes for LiCoO2.