Research And Preparation Of Air Electrode For Zinc-air Battery

At present, the more demand for engeny and the dwindling reserves of fossilenergy, energy use, conversion and new energy development caused widespreadconcern. A Fuel cell is a kind of efficient and cleaner energy, including thezinc-air battery which was the focus of attention for its excellent specific energyand safety. Zinc is low-cost because of its abundant reserves and has highspecific capacity. But the cost of noble metal catalyst prevent the zinc-air batteryfrom universal application. In this paper, the cheaper catalyst was studie d, topromote large-scale commercialization of zinc-air battery.Firstly of all, the carbon carriers were used as catalysts, the preformanceand pretreatment of different carbon （coal activated carbon, wooden activatedcarbon, chemical activated carbon, acetylene black, V-72R activated carbon,phenolic activated carbon） were studied. The results showed that: coal activatedcarbon and phenolic activated carbon show the higher preformance, and themethod for alcohol washed was the best pretreatment, and the mixture of V-72Ractivated carbon and alcohol washed coal activated carbon show the highestpreformance at the mass ratio1:5. The orthogonal tests of catalyst layer indicatedthat the highest performance shows at the mass ratio of carbon carrier, PTFE andNa₂SO₄20:6:5and without the adding acetylene black.Second, a cheaper MnO₂/C catalyst was systhesized for air electrode. Theinfluence of synthetic procedures and sources of manganese was investigated.The result indicated that: the best way to synthesize MnO₂/C catalyst is asfollows: synthesis of the normalization method, manganese sulfate as manganesesource, mass ratio of MnO₂and carbon carriers9:20, concentration of KMnO415g/L, molar ratio of MnSO4·H2O and KMnO41.5:1. The zinc-air battery whichused above-mentioned MnO₂/C as catalyst, output power of100mW/cm2. Thesingle factor analysis indicated that the catalyst layer with MnO₂/C catalystshows the highest performance at mass ratio of Na₂SO₄and carbon carrier1:4,mass ratio of PTFE and total carbon （carbon carrier and acetylene black）3:10and without adding acetylene black. The specific power could be improved afterair electrode soaked by ethanol. The air electrode is flattened by0.875MPa/cm2 pressure. Temperature affects the performance much at high temperature, and theeffects can be magnified with higher temperatures.Finally, nano-Ag/C catalyst was prepared by the polymer protection. Theresult indicated that: the catalyst shows the highest performance at mass ratio ofAgNO3and PVP2:1, concentration of Ag⁺was0.01mol/L. The result oforthogonal experiments indicated that the optimum mass ratio of carbon carrier,PTFE, Na₂SO₄and Ag is20:8:7:4. A complex catalyst MnO₂-Ag/C with highperformance is systhesized at the mass ratio of MnO₂and carbon carrier1:5. Theorder of catalyst performance is MnO₂-Ag/C, Ag/C, MnO₂/C and carbon carrierand the order of the stability is Ag/C, MnO₂-Ag/C, MnO₂/C and carbon carrier.The SWOT analysis method was adopted to analyse the market of zinc-airbattery. The result show that: the zinc-air battery equipped with MnO₂/C catalystshows high competitive power.