(吉首大學(xué) 生物資源與環(huán)境科學(xué)學(xué)院，吉首 416000)
摘 要: 采用原位包覆法制備表面包覆Li1.3Al0.3Ti1.7(PO4)3(LATP)的LiNi0.5Mn1.5O4(LNMO)，即LNMO@LATP正極材料。采用X-射線衍射(XRD)、掃描電鏡(SEM)、透射電鏡(TEM)及電化學(xué)測試等手段對其物相結(jié)構(gòu)、表面形貌及電化學(xué)性能進(jìn)行研究。結(jié)果表明：LATP 以無定型態(tài)緊密包覆于LiNi0.5Mn1.5O4的表面，包覆層厚度約為5 nm。由于LATP包覆層具有保護(hù)電極材料表面和提高鋰離子導(dǎo)電的雙重作用，減少了電極過程的副反應(yīng)，降低了電化學(xué)極化，提供了更多的鋰離子擴(kuò)散通道，導(dǎo)致LNMO@LATP具有比LNMO更穩(wěn)定的循環(huán)性能和更好的倍率性能，特別是在高溫的情況下。室溫下在0.2C放電時(shí)，LNMO@LATP和LNMO的首次放電容量分別為141.5和142.6 mA？h/g，經(jīng)80次循環(huán)后，二者放電容量保持率分別達(dá)到99.2%和98.0%；而在10.0C放電時(shí)，LNMO@LATP和LNMO的首次放電容量分別為93.5和70.6 mA？h/g，經(jīng)80次循環(huán)后，二者放電容量保持率分別達(dá)到66.1%和49.5%。當(dāng)循環(huán)溫度提高到55 ℃時(shí)，LNMO@ LATP和LNMO在0.2C循環(huán)80次后的放電容量保持率分別為95.5%和79.2%；而在10.0C放電循環(huán)80次后，放電容量保持率分別為88.0%和51.0%。
關(guān)鍵字: LiNi0.5Mn1.5O4；Li1.3Al0.3Ti1.7(PO4)3；高電壓正極；表面包覆；電化學(xué)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
