【作者】 杨鹰；

【导师】 叶红齐；

【作者基本信息】 中南大学 ， 化学工艺， 2002， 硕士

【摘要】 空气电极是锌空气电池的重要组成之一。影响空气电极性能的主要因素是氧还原催化剂和空气电极结构。采用柠檬酸辅助的前驱体法制备了ABO₃、AA’BO₃、ABB’O₃三个系列共十种钙钛石型氧化物催化剂。通过热重分析，确定了催化剂的焙烧制度。XRD分析表明，催化剂样品特征衍射峰明显，杂峰少，晶形完整。 常温H₂O₂催化分解实验表明，La_0.8Sr_0.2MnO₃催化分解活性较高，LaCoO₃的活性最高。通过测量稳态极化曲线和交流阻抗曲线，考察了催化剂的电化学活性，结果表明，La_0.8Sr_0.2MnO₃的电化学活性在所制备的催化剂中最高。总体上，催化剂的H₂O₂催化分解活性越高，其电化学活性也越高。但LaCoO₃表现异常，催化分解活性最高，电化学活性反而最小，可能是催化剂不稳定造成的。对AA’BO₃型和ABB’O₃型催化剂的研究表明，通过有选择地对钙钛石型氧化物催化剂的A位、B位金属离子进行部分替换，可使催化剂活性明显提高。 通过分析空气电极表面的传质过程，以La_0.8Sr_0.2MnO₃为催化剂，制作了多孔、疏水、透气的空气电极。在此基础上，以Hg／HgO电极作参比电极，镍网为对电极，制作了半电池模型。确定了制备空气电极的最优工艺条件，催化层PTFE含量约20％，厚度控制在0.20～0.35mm，疏水层厚度0.3mm，20MPa下冷压成型，电极各层采用D|S|A排布方式。结果表明，在-0.6V（Vs Hg／HgO）扫描电位下电流达到378mA，表明此空气电极具有较好的电极性能。极化曲线的数学处理表明，电极制备工艺稳定，重现性好。更多还原

【Abstract】 Air electrode is extensively equipped in fuel cell and metal-air battery, settled between the electrolyte and air, employed to be cathode in discharging procedure. In this article, the approaches to enhancing the air electrode performance were examined, namely preparing the more effective oxygen reduction catalysts to lessen the electrochemical polarization and improving the electrode structure to decrease the material diffusion resistance.Ten kinds of perovskite-type oxides were synthesized by the calcination of amorphous citric acid complex precursors. The thermal decomposition behavior of the precursor was examined by means of thermogravimetry (TG). X-ray diffraction verified the catalyst materials with obvious characteristic diffraction peaks and perfect crystalline phases.In the experiment of H2O2 catalytic decomposition, the catalytic decomposition activity of La0.8Sr0.2MnO3 was high and that of LaCoOs reached the highest among ten kinds of perovskite-type oxide catalysts. By measuring the curve of steady-state polarization and AC impedance , the electrochemical activity of catalyst was investigated. The results showed that La0.8Sr0.2MnO3 exhibits the highest electrochemical activity among all of the catalysts. It suggested that the higer the activity of H2O2 catalytic decomposition the higher the electrochemical activity with the exception of LaCoOs presumably for inherent instability. The study on AA’BOs and ABB’O3 showed that the partial substitution of A-site or B-site ion could always obtain new catalysts with good catalytic activity.Combined with the investigation of mass transfer on the surface of air electrode, the semi-hydrophobic and porous gas diffusion electrodes were fabricated by use ofas catalyst. Then employing Hg/HgO elecreode as reference electrode and nickel screen as counter electrode, a semi-cell model was made. The optimum conditions for air electrode preparation were shown as follow: 20% PTFE in active layer, thickness of active layer 0.2~0.35mm, diffusion layer 0.3mm, compacting pressure 20MPa and layers sequence D|S|A layout. The air electrode exhibited good performance that current was as high as 378mA at -0.6V ( Vs Hg/HgO ).The mathematical process of polarization curve revealed that the fabrication technique of air electrode was steady and prone to bring high electrode performance.更多还原