Ni0.8Co0.15Al0.05C2O4@Graphene的合成及电化学性能研究

过渡金属氧化物/石墨烯复合材料具有优异的电化学性能被广泛应用在锂离子电池中。本文以硫酸镍、硫酸钴、硫酸铝、草酸为原料按一定的物质的量比配制成溶液,在120°C的条件下水热反应12小时,得到多元过渡金属氧化物前驱体Ni_0.8Co_0.15Al_0.05C₂O₄(NCA-C₂O₄)；该前驱体经聚烯丙基胺盐酸盐修饰后,与氧化石墨烯进行复合并还原得到石墨烯包覆的多元过渡金属氧化物/石墨烯负极材料Ni_0.8Co_0.15Al_0.05C₂O₄@Graphene(NCA-C₂O₄@G)。对材料的结构、形貌和电化学性质进行了表征。扫描电镜测试结果显示样品粒度均一,具有两端不规则长方体形貌。电化学性能测试结果表明：石墨烯包覆后的NCA-C₂O₄@G充放电容量高于前驱体NCA-C₂O₄,NCA-C₂O₄@G复合材料在0.1C电流密度 (1C=1000 mAh/g)下首次放电比容量为1956 mA h/g；经过0.1C、0.2C、0.5C、1C、2C高倍率循环后,当测试电流密度恢复至100 mA/g时,复合材料比容量可迅速回升至720 mA h/g,并在随后50次循环中比容量保持稳定,显示出良好的循环稳定性和倍率性能。

Preparation andelectrochemical performance study of Ni0.8Co0.15Al0.05C2O4@Graphene material

Transition metal oxide/graphene composites have excellent electrochemical performance which are widely used in lithium ion batteries.In this work, with the raw materials of NiSO₄?6H₂O, CoSO₄?7H₂O, Al₂(SO₄)₃?18H₂O and H₂C₂O₄at a certain molar ratio prepared into solution, precursor Ni_0.8Co_0.15Al_0.05C₂O₄ was obtained by hydrothermal reaction for 12 h under 120°C; Then transition metal oxide/graphene composites Ni_0.8Co_0.15Al_0.05C₂O₄@Graphene were prepared by reduction of graphene oxide. And the structure, morphology and electrochemical properties of materials were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). SEM indicated that all the samples were cuboid with uniform size and irregular shape. Electrochemical test showed that the capacity of NCA-C₂O₄@G was higher than that of NCA-C₂O₄. And the first discharge capacity of NCA-C₂O₄@G composites at 0.1C density is 1956 mA h/g. After at 0.1C, 0.2C, 0.5C, 1C, 2C for cycles, the discharge capacity of composite material could be quickly increased to 720 mAh/g when the test conditions recovered to 100 mA/g, and the capacity remain stable in the subsequent 50 cycles. These indicate that the NCA-C₂O₄@G composites prepared have good electrochemical performance.