| In this paper, Zr4+, Y3+ and Ga3+ were doped into Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode material which was synthesized by combustion method and the influence of doping cations on the crystal structures and electrochemical properties of samples were studied. The morphologies and structures were characterized by scanning electron microscopy(SEM), thermal gravimetric-differential thermal analysis(TG-DTA) and X-ray diffraction(XRD) and the elemental chemical compositions were tested by inductively coupled plasma atomic emission spectrometry(ICP). Electrochemical properties were analyzed by galvanostatic charge-discharge test, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).Cathode materials with the formula of Li[Li0.2Mn0.54-xNi0.13Co0.13Zrx]O2(x=0.00, 0.01, 0.02, 0.03 and 0.06) were synthesized by using CH3COOLi·2H2O,(CH3COO)2Mn·4H2O,(CH3COO)2Ni·4H2O,(CH3COO)2Co·4H2O, Zr(NO3)4·5H2O and polyvinyl pyrrolidone(PVP)as raw materials. When Zr4+ doping ratio was 0.02, the discharge capacity of Li[Li0.2Mn0.52Ni0.13Co0.13Zr0.02]O2 was 280.3 m Ah·g-1 for the first cycle and 237.4 m Ah·g-1 after 50 cycles; the capacity retention was increased by 8.2% compared to the pristine sample. When the current density increased to 5.0 C under the potential range of 2.0~4.8 V, the capacity retention of the prepared sample was 76.5 m Ah·g-1 after 50 cycles, which is about 5 times higher than that of the pristine one. The low temperature performance of the synthesized sample was investigated, the discharge capacity increased by 61.1% after 50 cycles at-10 ℃. The superior electrochemical performances could be attributed to the improved stability of the Li-rich layered structure by Zr4+ doping.The Y+ doping was using Y(NO3)3·6H2O as Y3+ source, and the influence of the doping cations on structure, morphology and electrochemical properties were discussed. Li[Li0.2Mn0.54-xNi0.13Co0.13Yx]O2(x=0.00, 0.01, 0.02, 0.03, 0.06) were characterized by XRD and SEM, the results indicated that all the samples had a good α-Na Fe O2 layered structure and the particle size was similar with a uniform distribution. Electrochemical test results showed that when x=0.02, the initial discharge capacity of the doped sample was 281.4 m Ah·g-1and maintained at 252.1 m Ah·g-1 after 50 cycles, the capacity retention was 15.7% higher than theun-doped sample. It was demonstrated that Y3+ doping could improve the electrochemical performances of the Li[Li0.2Mn0.54Ni0.13Co0.13]O2 cathode materials.The Li[Li0.2Mn0.54-xNi0.13Co0.13Gax]O2(x=0.00, 0.02, 0.04, 0.06) were synthesized and it was found that all the samples have a well layered structure and uniform morphology. The electrochemical tests showed that when x=0.04, the prepared sample delivered a discharge capacity of 261.7 m Ah·g-1 for the first cycle and the capacity retention was 96.7% after 50 cycles. When the current density was at 0.1 C and cutoff voltage was between 2.0 and 4.8 V(vs. Li/Li+), the discharge capacity of Li[Li0.2Mn0.50Ni0.13 Co0.13Ga0.04]O2 remained at 254.3 m Ah·g-1 after 10 cycles. When the current density was increased to 1.0 C, the discharge capacity was 206.2 m Ah·g-1 after 20 cycles, which was 38.1 m Ah·g-1 higher compared to the pristine sample. The capacity increased from 15.0 to 47.2 m Ah·g-1 at 5.0 C after 40 cycles, which indicated that the Ga3+ doping significantly improved the rate performance of the material.
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