Electrochemical Hydrogen Storage Performance Of Co-based Alloy Composite Electrodes

In recent years,Co-based alloy has become a new energy storage and energy conversion material due to their good reversible electrochemical hydrogen storage performance,and can be used as a negative electrode material for nickel-hydrogen batteries.In this paper,Co_0.9Cu_0.1Si alloy was used as the research object.doping with palladium,muti-walled carbon nanotubes?MWCNTs?or Li-modified muti-walled carbon nanotubes?Li-MWCNTs?and mesoporous?-Fe₂O₃ were formed into cobalt-based alloys.The effects of composite on the structure and electrochemical properties of Co_0.9Cu_0.1Si alloy were studied.The research contents and results of this thesis are as follows:?1?Different amounts of palladium were doped into the Co_0.9Cu_0.1Si alloy by mechanical ball milling.A composite alloy of Co_0.9Cu_0.1Si+xPd?x=2.5,5 and 7.5 wt.%?was prepared.Studies have shown that the maximum discharge capacity of 5 wt.%Pd is559.2 mAh/g,and the cycle stability is also improved.In addition,the effects of milling time?0.5 h,1 h,2 h,3 h and 5 h?on the electrochemical properties of Co_0.9Cu_0.1Si+5wt.%Pd alloy were investigated.The ball milling time is 2 h,and the electrochemical performance is the best.Studies have shown that Pd-doping can accelerate charge transfer and improve the kinetics and electrochemical activity of alloy electrode reactions.?2?Composite materials of Co_0.9Cu_0.1Si alloy doping with different amounts of multi-walled carbon nanotubes?MWCNTs?or lithium modified muti-walled carbon nanotubes?Li-MWCNTs?were obtained via ball-milling.It was found that all composite materials have better electrochemical performance than Co_0.9Cu_0.1Si alloy.The electrocatalytic action of MWCNTs,the particle size reduction and specific surface area of Co_0.9Cu_0.1Si alloy can provide a larger electrochemical reach and a fast hydrogen transport channel.In addition,the simultaneous doping of Li-MWCNTs alloy is superior to that of pure MWCNTs alloy.After adding Li-MWCNTs,it is shown that MWCNTs and Li have synergistic effects in improving the discharge capacity and reaction kinetics of Co_0.9Cu_0.1Si alloy electrode.?3?The composite of Co_0.9Cu_0.1Si alloy and different amounts of mesoporous?-Fe₂O₃was formed by mechanical ball milling.It was found that the discharge capacities for the composites were higher than those for the Co_0.9Cu_0.1Si alloy and reached a maximum?605.9 mAh/g?with 5 wt.%content of?-Fe₂O₃,the composite alloys showed higher cycling stabilities,high-rate discharge ability and lower charge-transfer resistance.Due to the mesoporous structure and the large surface area of mesoporous?-Fe₂O₃,this facilitates hydrogen transport inside the alloy during charging/discharging.