Preparation And Electrochemical Properties Of Platinum-based Catalysts For Aluminum-air Batteries

Aluminum-air battery has high energy density and capacity density,and is a metal-air battery with great development potential.However,its slow oxygen reduction reaction（ORR）rate limits its development and application,and the development of low-cost and high-efficiency ORR catalysts is the key to promoting the development of aluminum-air batteries.Among various catalysts,platinum-based catalysts have the highest ORR activity and are considered to be the most ideal catalysts.But pure platinum content is limited and expensive,so the design and development of platinum-based catalysts with high platinum atom utilization,high activity,and high stability is the focus of current research.Firstly,the method of calcination after impregnation is adopted,and the control of platinum nanoparticles at 2～5 nm is realized by adjusting the conditions such as platinum loading and calcination temperature.Pt/C-400°C catalyst with uniform particle size was obtained at a platinum loading of 10%and a calcination temperature of 400°C,which exhibited better electrochemical performance than commercial JM Pt/C:the half-wave potential was 0.857 V,the mass activity can reach 0.087 A/mg _Pt,and the electrochemical active area（ECSA）has no decay after 5000 cycles of electrochemical scanning.The aluminum-air battery assembled with the air electrode based on this catalyst has a high and stable discharge plateau at a current of 10 m A,with a maximum power density of 4.32 m W cm^-2.In this paper,carbon-supported Pt-Zn nanoalloys were prepared by co-reduction on the surface of Vulcan XC-72R carbon black by impregnation reduction method.By adjusting the ratio of platinum to zinc,the Pt₃Zn/C catalyst with excellent performance was obtained.The electrochemical performance indicators are:the electrochemical active area is 85.0m²/g _Pt,the specific activity and mass activity at 0.9 V are 0.286m A/cm² and 0.244 A/mg _Pt,respectively,which are 1.93 times and 3.17 times that of JM Pt/C.The aluminum-air battery with Pt₃Zn/C as air cathode catalyst exhibits the highest power density of 5.86 m W/cm²,which is much higher than that of JM Pt/C.This work provides a new method to synthesize Pt-Zn alloy catalysts,which have broad application prospects in aluminum-air batteries.Finally,the application performance of the obtained platinum-based catalysts in aluminum-air batteries was studied,and the hydrogen evolution corrosion in neutral and alkaline electrolytes were compared.The performance of the aluminum-air battery was optimized by adjusting the cathode-anode distance,electrolyte concentration,electrolyte temperature and oxygen partial pressure.An 8-unit aluminum-air battery stack was assembled and the performance of the stack was studied.The stack can provide a high discharge voltage platform of 5.322 V when it is discharged at 10m A,and the peak power can reach 180 m W.