Study On The Electrochemical Performance Of La_0.7Mg_0.3Ni_2.8Co_0.5 Alloy Electrode Catalyzed By Graphene-supported Cu,Co And Ce0₂ Composite

La-Mg-Ni-based hydrogen storage alloy is one of the most promising Ni-MH battery anode materials and have more performance advantages,compared with the traditional AB5-type hydrogen storage alloy.Graphene is a new type of two-dimensional material with excellent conductivity,high specific surface area,and other excellent mechanical and electrical properties.Therefore,graphene is introduced into the traditional hydrogen storage surface modification process.Graphene-supported transition metal composite and graphene-supported rare earth oxide composite are prepared,the respective advantages of graphene and transition metal/rare earth oxides are exerted.Graphene composite have better synergistic effect,get more excellent catalytic performance,has become a research hotspot.In this paper,graphene-supported Cu composite(Cu@rGO),graphene-supported Co composite(Co@rGO)and graphene-supported CeO2(CeO2@rGO)were prepared by hydrogen reduction process.The prepared graphene composite were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results show that the graphene composite of Cu,Co and CeO2 particles on the graphene layer can be prepared by the process of this experiment.The La0.7Mg0.3Ni2.8Co0.5 alloy powder was catalyzed by the milling process,and the maximum discharge capacity,cycle life and high rate discharge performance(HRD)were tested.The electrochemical behavior of the Catalyzed La0.7Mg0.3Ni2.8Co0.5 alloy electrode in alkaline solution was studied by cyclic voltammetry,constant potential scanning,linear polarization curve,electrochemical impedance spectroscopy(EIS)and other electrochemical methods.The results show that:1.For the addition of 6 wt.%Cu@rGO Catalyzed La0.7Mg0.3Ni2.8Co0.5 alloy electrode,the maximum discharge capacity was 407.3 mAh·g-1.At different additions,the maximum capacity of the electrodes is improved.The addition of the Cu@rGO composite has improved the kinetics of the electrode with respect to the non-added electrode.Among them,the addition of 6 wt.%Cu@rGO alloy electrode's high magnification HRD1500 reached 76%.The modification of La0.7Mg0.3Ni2.8Co0.5 alloy powder with proper amount of Cu@rGO composite can improve the maximum discharge capacity,activation performance and high rate discharge performance of alloy electrode.2.For the addition of 9 wt.%Co@rGO Catalyzed La0.7MgO.3Ni2.8MCo0.5 alloy electrode,the maximum discharge capacity was 418mAh·g-1,while the unCatalyzed alloy electrode was only 374 mAh·g'-.The kinetics of the Co@rGO composite Catalyzed electrode are better than the unCatalyzed electrode.The 6wt.%Co@rGO Catalyzed alloy electrode high magnification HRD1500 reached 58%,and the unCatalyzed alloy electrode has zero HRD1500 under 1500mA·g-1 high current.Co@rGO composite modification can significantly improve the LaO0.7Mg0.3Ni2.8Co0.5 alloy electrode high rate discharge performance.However,by adding an excess of Co@rGO composite,the diffusivity of hydrogen in the electrode is reduced,resulting in a decrease in the high rate discharge performance of the electrode.3.In this experiment,the CeO2 Catalyzed alloy powder increased the anodic oxidation peak current of the alloy electrode,but decreased the diffusivity of hydrogen in the alloy electrode body,and the maximum discharge capacity was 403 mAh·g-1.While the maximum discharge capacity of the unCatalyzed alloy electrode is only 376 mAh·g-1.Graphene(rGO)Catalyzed electrode,can significantly improve the hydrogen in the alloy electrode body diffusion coefficient.CeO2@rGO composite can raise the anodic oxidation peak current density of the alloy electrode,but also improve the electrode diffusion coefficient of hydrogen.The maximum discharge capacity of the alloy electrode is increased,and the high-rate discharge performance of the electrode is improved.4.