【摘要】 为进一步提高动力电池正极材料锰酸锂（LiMn₂O₄）的循环稳定性,通过溶胶-凝胶法用快离子导体La_0.8Sr_0.2MnO₃作为包覆材料对LiMn₂O₄进行表面修饰,探讨了不同包覆量对复合材料电化学性能的影响。采用X射线衍射仪（XRD）、场发射扫描电镜（FESEM）和透射电子显微镜（TEM）对样品的微观结构以及形貌进行表征。结果表明:La_0.8Sr_0.2MnO₃的包覆并没有改变LiMn₂O₄晶体结构及空间构型;相比纯的LiMn₂O₄样品,La_0.8Sr_0.2MnO₃包覆后的样品颗粒表面较为粗糙;涂层为薄膜状结构,均匀且完全包覆在LiMn₂O₄颗粒的表面。利用电化学测试方法测试其电化学性能,测试结果表明,当La_0.8Sr_0.2MnO₃包覆量为5%时,具有较好的电化学性能,首次放电比容量为127.4 m A·h/g（0.1 C）,25℃循环400次后容量保持率为91.2%,55℃循环100次后容量保持率为91.1%;与未经表面修饰的样品相比,其首次放电比容量为119.1 m A·h/g（0.1 C）,400次的容量保持率为61.9%,100次容量保持率为77.9%,La_0.8Sr_0.2MnO₃包覆后的样品的电化学性能尤其是循环性能得到明显的提高。更多还原

【Abstract】 LiMn₂O₄ coated with La_0.8Sr_0.2MnO₃ fast ionic conductor was synthesized by sol-gel method,and the influence of coating content on the electrochemical performance was explored.X-ray diffractometer（XRD）,field emission scanning electron microscope（FESEM） and transmission electron microscope（TEM） were employed to characterize the microstructure and morphology of sample.Results showed that La_0.8Sr_0.2MnO₃ coating did not change the crystal structure and spatial configuration of LiMn₂O₄.Compared with pure LiMn₂O₄,the sample particles coated with La_0.8Sr_0.2MnO₃ appeared rougher surface.The coating was membranous structure,and entirely coated the surface of LiMn₂O₄ particles.In addition,the electrochemical performance was evaluated by electrochemical method,and the test showed that when La_0.8Sr_0.2 MnO₃ content was 5%,the sample had better electrochemical performance with 127.4mA ? h/g（0.1 C） of discharge specific capacity of the first cycle,91.2%of capacity retention ratio after 400 times cycle at 25 ℃and 91.1%after 100 times cycle at 55 ℃.By contrast,the initial LiMn₂O₄ without modification had only 119.1 mA ? h/g at 0.1 C,the capacity retention ratios were 61.9%and 77.9%after 400 and100 cycles,respectively.Therefore,the electrochemical performance,especially cycle performance of LiMn₂O₄ coated with La_0.8Sr_0.2MnO₃ was improved apparently.更多还原