Preparation And Electrochemical Hydrogen Storage Properties Of Co_0.9Cu_0.1Si Composites

Cobalt-based hydrogen storage alloys have been widely studied for their good cyclic stability and high discharge capacity.However,cobalt is expensive and environmental pollution is serious,so the use of cobalt should be reduced.In this paper,cobalt-copper-silicon raw materials were prepared by mechanical alloying.Cobalt-copper-silicon alloy was used as the research object.Cobalt-based alloy-based composite materials were formed by doping nitrogen-sulfur co-doped graphene（NSG）,cobalt-nitrogen co-doped graphene（Co-N@r GO）,molybdenum carbide-loaded carbon nanotubes（Mo₂C@MWCNTs）and nickel-doped cerium dioxide（Ni-Ce O₂）.The morphology,structure and performance of the composite materials were studied.The composite materials were prepared into negative materials of nickel-hydrogen battery to analyze their electrochemical hydrogen storage performance.The research results of this paper are as follows:1.Graphene oxide（GO）,nitrogen-doped graphene（NG）and nitrogen and sulfur co-doped graphene（NSG）were doped into Co_0.9Cu_0.1Si alloy by mechanical alloying.It was found that the properties of the multiphase material were better than those of the matrix Co_0.9Cu_0.1Si alloy.This is due to the high surface area and excellent conductivity of graphene,which accelerates the charge transfer and the addition of nitrogen and sulfur improves the electrocatalytic activity of graphene.At the same time,in order to determine the optimal proportion,3%,5%,7%and 10%NSG were doped into Co_0.9Cu_0.1Si alloy.The results show that the discharge capacity of Co_0.9Cu_0.1Si multiphase material doped with 5%NSG reaches 580.1 m Ahg^-1,and the capacity retention rate reaches 64.1%.The electrochemical kinetic performance of the alloy electrode was improved.2.Reduced graphene oxide（r GO）,nitrogen-doped graphene（N@r GO）,cobalt-doped graphene（Co@r GO）and cobalt-nitrogen co-doped graphene（Co-N@r GO）were doped into Co_0.9Cu_0.1Si alloy by mechanical alloying.It was found that the properties of the multiphase material were better than those of the matrix Co_0.9Cu_0.1Si alloy.This is because graphene has excellent electrical conductivity,nitrogen doping causes a large number of surface defects,which is beneficial to the adhesion of hydrogen.And cobalt doping also has a good effect on energy conversion.At the same time,in order to determine the optimal proportion,3%,5%,7%and 10%NSG were doped into Co_0.9Cu_0.1Si alloy.The results show that the discharge capacity of Co_0.9Cu_0.1Si multiphase material doped with 5%NSG reaches 584.6 m Ahg^-1,and the capacity retention rate reaches 64.6%.The electrochemical kinetic performance of the alloy electrode was improved.3.Molybdenum carbide（Mo₂C）,carbon nanotubes（MWCNTs）and carbon nanotubes loaded with molybdenum carbide（Mo₂C@MWCNTs）were doped into Co_0.9Cu_0.1Si alloy by mechanical alloying method.It was found that the properties of the multiphase material were better than those of the matrix Co_0.9Cu_0.1Si alloy.This is due to the excellent conductivity of carbon nanotubes and the strong catalytic activity of molybdenum carbide.The carburizing process makes it uniformly dispersed on the carbon nanotubes,and the covalent binding structure provides a highly exposed reaction site,which is beneficial to the adhesion of hydrogen.At the same time,in order to explore the optimum concentration of Mo₂C@MWCNTs,under the condition of keeping the amount of carbon nanotubes unchanged,by changing the amount of ammonium molybdate to change the concentration of Mo₂C@MWCNTs,5%of different concentrations of Mo₂C@MWCNTs were doped into Co_0.9Cu_0.1Si alloy,the discharge capacity and cycle stability of the composite materials were significantly improved,and the electrochemical kinetics of the alloy electrode was improved.4.Cerium oxide（Ce O₂）and nickel doped cerium oxide（Ni-Ce O₂）were doped into Co_0.9Cu_0.1Si alloy by mechanical alloying method.It was found that the properties of the multiphase material were better than those of the matrix Co_0.9Cu_0.1Si alloy.At the same time,in order to determine the optimum proportion,different proportions of cerium oxide and nickel doped cerium oxide were doped into Co_0.9Cu_0.1Si alloy.The results show that when the mass ratio of Co_0.9Cu_0.1Si alloy and doping is 20:1,the electrochemical hydrogen storage performance of the composite material is the best,and at the same mass ratio,the composite material doped with nickel doped cerium oxide is better than the composite material doped with cerium oxide,because cerium oxide has high specific capacitance and good reversibility,nickel reserves are rich,low cost,good electrochemical performance,and nickel doping enhances the conductivity.The electrochemical hydrogen storage performance of Co_0.9Cu_0.1Si alloy was significantly improved by doping.