Study Of Ag/C Catalyst Preparation And Its Performance

In modern society, the energy crisis and environmental protection problemincreasingly become the focus that everybody pays close attention to,the developmentof green and clean energy has become the topic of Times developing. Zinc air batteryisn’t only a very promising metal air battery, but also one of green and clean energy.Zinc air battery becomes the focus of everybody’s attention, which has the followingcharacteristics: low price, large energy density, high specific capacity and cleanlinesswithout any pollution.In order to realize large-scale industrialization and commercialization of zinc airbattery, it has great significance to develop catalysts with low price and high catalyticactivity. Ag/C catalyst has advantages of low price and high catalytic activity. Silverparticles will reunite, which is a considerable factor not to be ignored during preparationof Ag/C catalyst. The increase in particle size and decrease in specific area are inducedby the reunion and then affect catalysis effect.In this study, a preparation method of Ag/C catalyst was proposed by usingpolymer molecule to protect AgNO₃. NaBH4was used as the reducing agent andPolyvinylpyrrolidone（PVP） was used as protective agent in this method. When massratio of PVP to AgNO₃were2:1,5:1and10:1, Ag/C catalysts whose mass fractionwere10%,20%,40%were prepared respectively. Ag/C catalysts were separatelyprepared with different addition order of carrier active carbon, when the mass ratio ofPVP to AgNO₃was constant and the concentrations of Ag+were different. The aboveprepared Ag/C catalysts were characterized by XRD and SEM. The Ag/C catalyst wasused to prepare air electrode which was tested electrochemical performance by threeelectrode system. Zinc air battery was measured performance, consisting of air electrodeloading Ag/C catalyst as the anode and zinc electrode as the cathode.Research shows that the polarization current and catalytic activity of air electrodeincreased gradually, the polarization curve of zinc air battery had a increasing trend andthe power density had a increasing tendency, with the increase of catalyst content from10%to40%. The polarization of the prepared Ag/C electrode was reduced and thepower density of zinc air battery was greater when [Ag⁺]=0.01mol/L; when carrieractive carbon was added first in the preparation process of catalyst, the catalytic activityof Ag/C catalyst was relatively great, the polarization of air electrode was decreased andpower density of zinc air battery became greater. Under optimized experimentalconditions of discharge performance of zinc air battery, the polarization of electrodewas least and power density was greatest when the mass fraction of silver catalyst was 40%; the discharge performance of battery was highest when the mass fraction of poreformer was50%. The catalytic activity of Ag/C catalyst was relatively great when thetemperature was200℃.when PTFE content was40%, the discharge performance of airelectrode was better.