烧结温度对LiMn2O4基502030锂离子电池电化学性能的影响

摘要

In order to study the electrochemical performance of La0.7Sr0.3MnO3@LiMn2O4(LLMO)cathode ma-terial at different heat annealing temperatures,the structure and morphology of La0.7Sr0.3MnO3coating on the surface of spinel LiMn2O4cathode materials were investigated by X-ray diffraction (XRD)and transmission e-lectron microscopy (TEM).And the electrochemical performances of the LLMO samples were tested by elec-trochemical tests via full cells (502030).The XRD results show that there is no other diffraction peak in the La0.7Sr0.3MnO3coating with a mass fraction of 1.0 %,indicating that the La0.7Sr0.3MnO3coating does not change the spinel structure of LiMn2O4cathode material,because the atoms of coating material can only adhere to the surface rather than enter the spinel lattice.Heat annealing temperature has a significant effect on the elec-trochemical performance of the La0.7Sr0.3MnO3coating.At the mid-temperature (500 ℃),TEM results exhibit a more uniform and continuous coating,and its thickness is about 80 nm.The electrochemical results indicate that LLMO sample exhibits a good initial charge-discharge efficiency and cycle stability.The initial charge-dis-charge (0.1 C rate)efficiency of pure LiMn2O4is 85.97%,and the capacity retention rate is 82.09% after 400 cycles,while the initial charge-discharge efficiency of the sample annealed at 500 ℃ is 98.74%,and the capacity retention rate is 88.89% after 400 cycles.Thus,the La0.7Sr0.3MnO3@LiMn2O4annealed at 500 ℃ has an excel-lent electrochemical performance,showing potential for high power applications in lithium ion batteries.%为了研究不同烧结温度对La0.7Sr0.3MnO3@LiMn2O4(LLMO)材料电化学性能的影响,采用 X射线衍射(XRD)和透射电子显微镜(TEM)对其结构和形貌进行表征,将 LLMO 材料制作成502030型软包锂离子电池,测试其电化学性能.XRD结果表明,La0.7Sr0.3MnO3包覆后的材料没有其它衍射峰,说明质量分数为1.0%的La0.7Sr0.3MnO3包覆并没有改变LiMn2O4结构;TEM表明烧结温度为500 ℃时,表面包覆分布均匀,涂层厚度约为80 nm.对材料进行电化学性能测试,测试结果表明,纯相LiMn2O4首次充放电(0.1 C倍率)效率为85.97%,循环400周后容量保持率为82.09%;500 ℃热处理的样品首次充放电效率为98.74%,循环400周后容量保持率为88.89%.实验结果表明,经过包覆后LiMn2O4材料的电化学性能得到了明显的提高.