【摘要】 采用TiO₂对LiNi_0.5Mn_1.5O₄ （LNMO）正极材料进行表面包覆,以达到改善LNMO电化学性能的目的。利用X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、恒流充放电、循环伏安（CV）和交流阻抗（EIS）测试手段对制备的材料进行结构表征和电化学性能评价。结果表明,TiO₂能够在LNMO表面形成包覆层,且LNMO-T-2样品（TiO₂包覆量为w=1.0%）表现出最为优异的倍率性能及循环稳定性。LNMO-T-2样品在5和7 C (1 C=140 mAh·g^-1)倍率下的放电比容量为102.3和72.1 mAh·g^-1,比未包覆改性的LNMO分别提高14.3%和33.5%。另外,LNMO-T-2样品在2 C倍率下进行200次循环后放电比容量保持率达到87.9%,高于未包覆改性的LNMO的放电比容量保持率（82.7%）。LNMO-T-2样品电化学性能的改善归因于TiO₂表面包覆可以有效减小电极极化,同时降低电荷转移阻抗(R_ct)。更多还原

【Abstract】 LiNi_0.5Mn_1.5O₄（LNMO） cathode materials were coated by TiO₂ to enhance electrochemical performance. Structural characterization and electrochemical performance evaluation of the prepared materials were studied by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, transmission electron microscope（TEM）, X-ray photoelectron spectroscopy system（XPS）, galvanostatic charge-discharge, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS） tests. The results indicate that there is a TiO₂ layer on the surface of LNMO, and the LNMO-T-2 sample coated with w = 1.0% TiO₂ exhibits the best rate capability and cycling stability. The corresponding discharge capacities of LNMO-T-2 were 102.3 and 72.1 m Ah·g^-1, respectively, which showed an improvement of 14.3% and 33.5% at 5 and 7 C(1 C = 140 mAh·g^-1)compared with raw LNMO. Moreover, LNMO-T-2 kept 87.9% discharge capacity after 200 cycle charge-discharged tests at 2 C, which was higher than raw LMNO（82.7%）. The improvement was due to TiO₂ can reduce electrode polarization and charge-transfer resistance(R_ct).更多还原