固体电解质包覆LiMn2O4正极材料的合成及表征

Synthesis and characterization of Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4

摘要:

采用湿化学法制备Li1.3Al0.3Ti1.7(PO4)3包覆LiMn2O4。采用X-射线衍射、扫描电镜、恒电流充放电等技术对合成产物进行物相、形貌和电化学分析。结果表明：Li1.3Al0.3Ti1.7(PO4)3包覆LiMn2O4与LiMn2O4有相似的X-射线衍射结果，LATP包覆后的LiMn2O4循环伏安峰电流和电荷转移阻抗变化不大。室温及55℃以0.2C充放电倍率循环40次时，Li1.3Al0.3Ti1.7(PO4)3包覆LiMn2O4的容量保持率分别为98.2%和93.9%，高于未包覆LiMn2O4的85.4%和79.1%。当以2C倍率室温充放电循环时，Li1.3Al0.3Ti1.7(PO4)3包覆LiMn2O4的容量保持率比未包覆LiMn2O4高8.4%；55℃充放电循环时，Li1.3Al0.3Ti1.7(PO4)3包覆LiMn2O4的容量保持率比未包覆LiMn2O4高11.1%。

Abstract:

Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 was prepared by wet chemical route. The phase, surface morphology, and electrochemical properties of the prepared powders were characterized by X-ray diffraction, scanning electron micrograph, and galvanostatic charge-discharge experiments. Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 has similar X-ray diffraction patterns, cyclic voltammograms, and charge-transfer resistance as LiMn2O4. The two powders show similar values of lithium-ion diffusion coefficient. When cycled at room temperature and 55癈 for 40 times at the charge-discharge rate of 0.2C, Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 shows capacity retention of 98.2% and 93.9%, respectively, which are considerably higher than the values of 85.4% and 79.1 % for the uncoated one. Both the capacity retention difference between LATP-coated LiMn2O4 and LiMn2O4 cycling at room temperature and 55癈 become larger with the increase of the charge-discharge rate. When the charge-discharge reaches 2C, the capacity retention of LATP-coated LiMn2O4 becomes 8.4% higher than uncoated LiMn2O4 for room temperature cycling, and it becomes 11.1% higher than the latter when cycled at 55癈.