Preparation And Performance Study Of Ag-coated MnO₂ Aluminum-air Battery Cathode

As a new type of green chemical power source,aluminum air battery has the advantages of abundant raw materials,low price,high specific energy and long service life.The catalytic activity and stability of the catalyst in the air electrode affects the further application of aluminum air cells.In this thesis,AgNO₃ was used as precursor to prepare Ag-coated MnO₂ catalyst?linear and spherical?by chemical reduction method and used as active component to optimize catalyst loading.The interaction between Ag and MnO₂ was investigated.The methods of preparation of activated carbon and pretreatment were studied.The preparation conditions of the catalyst were investigated and a series of Ag-based catalysts were prepared.XRD,SEM,XPS and other characterization methods show that the spHerical MnO₂ is better than the linear?-MnO₂ deposited silver particles,and the Ag particles are coated with MnO₂.The 50%Ag-MnO₂ is determined as the best coating quality ratio.When the concentration of current precursor AgNO₃ is:10g/L,the number of transferred electrons at 0.6 V during catalytic oxygen reduction is 3.86 and the yield of hydrogen peroxide is the lowest,6.3%;In addition,when the pH of the solution is about 10.4,the reduction rate of Ag is the largest,so that the powder gains the most.Pretreatment of Vulcan XC-72 carbon carrier and adjustment of the ratio showed that the internal resistance of the electrode was the smallest when the mass ratio of?Ag/MnO₂?:C was 1:1 and the pretreatment was much more optimized than the untreated property.It is calculated from the electrochemical performance test that the number of transferred electrons in the catalytic oxygen reduction reaction of the catalyst is about 3.8,which is basically a catalytic oxygen reduction reaction according to the 4-electron reaction pathway;When the PTFE content in the waterproof gas permeable layer is 60%,the electrode polarization is the smallest and the electrochemical performance is the best;The tablet forming pressure also has a great influence on the electrode performance.When the tableting pressure is 10 MPa,the carbon particle bonding degree is suitable.The gas and liquid forest have good diffusion performance.In the constant current test,the stable potential of the Ag/MnO₂/C gas diffusion electrode is about 20 mV lower than the stable potential of the Pt/C gas diffusion electrode,but is about 140 mV higher than the conventional Ag/C gas diffusion electrode.The whole discharge process is relatively stable.There is no obvious fluctuation and the stable voltage is around 1.45V.