(吉首大学 生物资源与环境科学学院，吉首 416000)
摘 要: 采用原位包覆法制备表面包覆Li1.3Al0.3Ti1.7(PO4)3(LATP)的LiNi0.5Mn1.5O4(LNMO)，即LNMO@LATP正极材料。采用X-射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)及电化学测试等手段对其物相结构、表面形貌及电化学性能进行研究。结果表明：LATP 以无定型态紧密包覆于LiNi0.5Mn1.5O4的表面，包覆层厚度约为5 nm。由于LATP包覆层具有保护电极材料表面和提高锂离子导电的双重作用，减少了电极过程的副反应，降低了电化学极化，提供了更多的锂离子扩散通道，导致LNMO@LATP具有比LNMO更稳定的循环性能和更好的倍率性能，特别是在高温的情况下。室温下在0.2C放电时，LNMO@LATP和LNMO的首次放电容量分别为141.5和142.6 mA？h/g，经80次循环后，二者放电容量保持率分别达到99.2%和98.0%；而在10.0C放电时，LNMO@LATP和LNMO的首次放电容量分别为93.5和70.6 mA？h/g，经80次循环后，二者放电容量保持率分别达到66.1%和49.5%。当循环温度提高到55 ℃时，LNMO@ LATP和LNMO在0.2C循环80次后的放电容量保持率分别为95.5%和79.2%；而在10.0C放电循环80次后，放电容量保持率分别为88.0%和51.0%。
关键字: LiNi0.5Mn1.5O4；Li1.3Al0.3Ti1.7(PO4)3；高电压正极；表面包覆；电化学性能
（College of Biology and Environmental Science, Jishou University, Jishou 416000, China）
Abstract:LiNi0.5Mn1.5O4 (LNMO) cathode materials coated with lithium ion conductor Li1.3Al0.3Ti1.7(PO4)3 (LATP), namely LNMO@LATP cathode, was prepared by in situ coating method. X-ray diffraction(XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical measurements were used to evaluate the properties of the cathodes. The results show that the coating of LATP does not change the structure of LNMO, and the LATP is attached tightly on the surface of LNMO in amorphous form. The coating layer of LATP is about 5 nm. Due to the dual roles of protecting the surface of LNMO and improving of lithium ion conductivity of LATP, LNMO@LATP cathode can reduce the side reaction between the electrolyte and LNMO, decrease the electrochemical polarization and provide more lithium ion diffusion channels in cycling, which leads to that LNMO@LATP cathode exhibits more enhanced cycling performance and better rate capability than the uncoated LNMO, especially at high temperature. The initial discharge capacities of LNMO@LATP and LNMO are 141.5 and 142.6 mA？h/g, respectively, 99.2% and 98.0% of their initial discharge capacity can be kept up after cycling at 0.2C for 80 times at room temperature. Under the discharge conditions of cycling at 10C for 80 times, the initial discharge capacities of LNMO@LATP and LNMO are 93.5 and 70.6 mA？h/g with a capacity retention rate of 66.1% and 49.5%, respectively. When cycled at 55 ℃ for 80 times, the capacity retention rates of LNMO@LATP and LNMO are 95.5% and 79.2% at 0.2C rate, and 88.0% and 51.0% ar 10.0C rate, respectively.
Key words: LiNi0.5Mn1.5O4；Li1.3Al0.3Ti1.7(PO4)3; high voltage cathode; surface coating; electrochemical property
