Preparation And Characterization Of Positive Materials For Aluminum-Air Battery

Aluminum-air battery is a kind of environmental power with high energy density. Oxygen reduction electrode is important part of the cell, the improvement of the cathode will promote the development of high-energy chemical powder. In this dissertation, sol-gel method was applied to prepare the perovskite catalysts, including powders doping Co on B site of La0.6Ca0.4MnO3. A series of La_0.6Ca_0.4Co_xMn_1-xO_3-δ catalysts with different x values (x from 0 to 0.9) were obtained. The effects of pH value, calcination tempeature, mole ratio of metal to citric acid on the catalytic activity were discussed. XRD, IR, SEM, XPS, TG-DTA and particle size distribution were used to research the catalyst powders, moreover, CV and polarization curves, electrochemical impedance spectroscopy and constant current discharge were used to test the oxygen reduction electrode. According to the orthogonal experiment, the perovskite oxides'suitable preparation conditions was determined. In this thesis, composite catalysts, current collector and electrode configuration were also discussed.When x=0.3, perovskite oxide La_0.6Ca_0.4Co_xMn_1-xO_3-δ has the best catalytic activity. According to the XPS analysis, that's because of the abundant chemically adsorbed oxygen on the powder surface. Besides, La, Ca, Mn appeared +3, +2, +3, respectively, Co get two valence states of +2 and +3. When pH=4 at the sol preparation, catalyst obtains the minimum average size of 12.128 m, which is result from combined effects between the three-dimensional network structure and agglomeration. At R=1:2(R: the mole ration of metal ions to citric acid ), catalyst shows better electrochemical acitivity. The orthogonal experiment shows the optimum preparation condition of La_0.6Ca_0.4Co_xMn_1-xO_3-δ is: pH=6, x=0.3, T=600℃, R=1:3. The EIS test shows that the polarization resistance of oxygen elctrode is mainly caused by the charge transfer resistance. From SEM, the air electrode displayed bigger blocks and less pore size after discharged.When perovskite oxide composited with MnO₂ and Ag respectively, the suitable mass rations are 1:2. Nickel foam is a better current collector in the air electrode because of its porous nature through which the oxygen can pass easily. Configuration of diffusion layer/current collector/diffusion layer/catalyst layer was applied to the air electrode, not only can get a better battery performance, but also reduce the electrolyte leakage and Nickel's corrosion.