Preparation And Electrochemical Characterization Of The Silver-nickel Catalyst And Catalyst Layer In Aluminum-air Battery

With the depletion of fossil energy,the development of new energy sources has become a top priority.The anode of the metal-air battery uses a reactive metal for the electron-depleting reaction,and the cathode absorbs the oxygen in the air for the oxygen reduction reaction.The battery does not emit any pollution during the discharge process,and is a clean and efficient energy system.Since the theoretical energy density of an aluminum-air battery is only lower than that of a lithium-air battery in a metal-air battery,and aluminum is richer in resources and lower in price than metal lithium,the aluminumair battery has broad application prospects.A major problem affecting the industrial production of aluminum-air batteries is that the polarization of the air electrode is severe and the service life is not long.The cause of this phenomenon is that the activity of the catalyst is not high and the hydrophobicity inside the air electrode is too low.This paper will start from two aspects of improving catalyst activity and improving the internal structure of the catalytic layer.The key point is to optimize the relevant parameters and improve the discharge performance of the air electrode.The Ag/C catalyst was modified by changing the loading of Ni relative to the catalyst,and the physical properties of the silver-nickel catalyst were characterized by means of XRD,TEM,etc.,and then the structure of the Ag-Ni catalyst was observed by SEM and HRTEM.It was found that when the loading of Ni was 7.76 mass %,the half-wave potential of the Ag-Ni/C catalyst was 0.695 V(?s.RHE)which was shifted by 56 m V compared with the Ag/C catalyst.After the catalyst was prepared as an air electrode,the electrode potential reached-0.774 V(?s.Hg/Hg O)under a constant current discharge of 100 m A·cm-2,and the potential was shifted by 34 m V compared with the air electrode before the modification.This shows that the discharge performance of the air electrode is improved after the Ni-modified catalyst is used.The amount of Ni supported in the catalyst and the preparation conditions of the catalyst were then optimized.It is found that when the loading of Ni is 19.4 mass %,the reduction temperature of the catalyst is 80 °C,and the amount of reducing agent is 3 times of the theoretical amount,the performance of the aluminum-air battery is optimal.Under this condition,the operating voltage of the aluminum-air battery at 100 m A·cm-2 is stabilized at 1.421 V.The structure of the catalytic layer is optimized.Including the effects of various parameters on the physical properties of the catalytic layer preparation process,and the optimization of the factors in the preparation process by orthogonal test.The results of the orthogonal test show that the change of PTFE content has the greatest influence on the electrode potential of the air electrode.The electrode potential of the air electrode prepared using the optimized parameters was-0.288 V(?s.Hg/Hg O)at 100 m A·cm-2.A pore former was added to the catalyst layer to investigate the effect of different types and amounts of pore former on the performance of the air electrode.The results show that the addition of 25 mass % PEG-200 can effectively increase the number of secondary pores inside the catalytic layer and increase the discharge capacity of the electrode.The air battery produced under these conditions can reach an operating voltage of 1.49 V.