Synthesis Of Ag-Cu Catalyst And Application In Zinc-air Battery

Recently,metal-air battery has attracted more and more attention due to its high energy density,high-efficient,low cost and environment friendly.Oxygen reduction reaction?ORR?is the hot research topic in metal-air battery.In order to improve the catalytic activity and stability,lower the price of catalysts,it is much important to research the Ag-based catalysts.In this paper,we focus on the research of catalytic activity of Ag-Cu catalysts for oxygen reduction reaction.The galvanic displacement and electrodeposition methods were taken to synthesize the Ag-Cu bimetallic catalysts with dendritic morphology and Ag-Cu alloy with spheral morphology,respectively.The electrochemical methods were taken to investigate the catalytic activity of Ag-Cu catalysts.The catalytic mechanism of Ag-Cu catalysts for oxygen reduction reaction was studied by combining the physical characterization and the catalytic activity of Ag-Cu catalyst.The main conclusions of this paper is following:?1?The Ag-Cu catalyst was synthesized directly on Ni foam,which was regarded as the current collection,by galvanic displacement method.The product without carbon and binder was used as the air electrode of metal-air battery.The morphology of this Ag-Cu catalyst is dendrite with bimetallic structure.The concentration of CuSO₄ and AgNO₃ is the main parameters for the morphologies of Ag-Cu catalysts.The best condition for the synthesis of Ag-Cu catalysts with hierarchical dendrites is following: firstly,Ni foam was dipped into 0.3 M CuSO₄ solution for 2 h;then,the product was dipped into 10 mM AgNO₃ for 120 s.The transferred number of oxygen reduction reaction catalyzed by Ag-Cu bimetallic catalyst is 4.Ag-Cu bimetallic catalyst is 2 times more catalytically active in the oxygen reduction reaction than a pue Ag catalyst.The discharge voltage at 20 mA cm-2 of the Ag-Cu bimetallic catalyst based primary zinc-air battery is 1.11 V.The specific capacity and power density is 572 mAh g^-1and 641 mWh g^-1,respectivity.The round-trip efficiency of rechargeable zinc-air battery is 53.9%.?2?The Ag-Cu alloy was synthesized by electrodeposition method.The Ag-Cu nanoalloys with different Cu contents were synthesized by changing the mol ratio of Ag+ and Cu2+ in the precursor solutions.We also concluded that the effective Cu contents to improve the catalytic activity of Ag-Cu catalysts is 17%-40% by the results of the RDE curves of different Ag-Cu alloys.The catalytic activity of Ag-Cu catalyst is a 2.5fold improvement over pure Ag catalyst.The Ag-Cu alloy has enhanced resistance to oxidation.The discharge voltage at 20 mA cm-2 of the Ag-Cu alloy catalyst based primary zinc-air battery is 1.18 V.The round-trip efficiency of the rechargeable zinc-air battery is 56.4%.Ag-Cu alloy catalyst has excellent tolerance of CO₂ in the zinc-air battery.