Preparation Of Nanometer La_1-XSr_xMnO₃ And Its Use In Air Electrode

Air electrode is one of the most important components in zinc-air cell. The main effect factors on performance of air electrode are catalysts'oxidation and deoxidization capability and structure of oxygen electrode. In this paper, nanometer perovskite-type catalysts La1-xSrxMnO3 are prepared by citric acid sol-gel method that add surface-active agent.In this paper, the optimum conditions of catalyst preparation were found by studying the influences of the sol-gel process parameters on the crystal structure of the nanometer La1-xSrxMnO3, such as the value of original solution pH, the temperature of water bath, the baking temperature of sol. The baking condition of perovskite-type oxide is confirmed by means of TG-DTA. At last, the catalyst with good performance were prepared as follows: mixed the metal ion and citric acid together by molar ratio of 1:2, then the mixture was dissolved in 150ml water with original solution pH value of 5.0 to prepare the sol; then the water in the sol was vaporized for 5h in water bath at temperature of 80℃, and the gel is dried for 10h at the temperature of 90℃. At last, the catalyst is prepared after roasting the gel for 5h at 700℃. It is verified that the oxide have obvious characteristic diffraction peaks and less impurity by X-ray diffraction (XRD). The average diameter of the catalysts, observed by the Transmission Electron Microscope (TEM), is 20~30nm.Experiments showed that the semi-hydrophobic and porous gas diffusion electrodes were fabricated by use of La0.7Sr0.3MnO3 as catalyst. Meanwhile, employing Hg/HgO elecreode as reference electrode and nickel foam as counter electrode, a semi-cell model was made. The optimum conditions for air electrode preparation were shown as follows: active carbon which was baked for 15 min in 900℃as carrier for catalyst, bond is 60mass% polytetrafluoroethylene(PTFE) liquor, 20% PTFE in waterproof layer, 10mass% pore-making in waterproof layer thickness of waterproof layer 0.30mm, 10mass% PTFE in catalysis layer, nickel screen for current collector, compacting pressure 6MPa. The air electrode exhibited so good performance that current density was as high as 163.33mA at -0.3V(vs. Hg/HgO). The electrode that was prepared with above method can...