氧电极催化剂的制备及可充锌—空气电池工艺研究

【作者】 曹兴；

【导师】 唐有根；

【作者基本信息】 中南大学 ， 应用化学， 2010， 硕士

【摘要】 双功能氧电极催化剂是二次锌-空气电池研制的关键问题之一；此外,空气电极的结构和锌电极的结构对二次锌-空气的性能也有极大的影响。本文对空气电极催化剂的合成、空气扩散电极的制作方法以及锌电极集流体进行了比较系统的探索和研究。采用改进的溶胶-凝胶法合成了钙钛矿型双功能氧电极催化剂LaNi0.8Co0.2O3。采用XRD、SEM、TEM对催化剂进行了表征和物相分析。用极化曲线、交流阻抗技术、恒流放电曲线等电化学手段对催化剂在7mol/L KOH溶液中的电化学性能进行了测试。采用改进的溶胶-凝胶法制备LaNi0.8Co0.2O3,在前驱体中按n(总金属离子)：n(石墨)为1：1添加石墨,在不同温度下制得了催化剂氧化物,结果表明,其中以500℃下制得的催化剂团聚最小,催化活性最高,以此产物为催化剂制备的空气电极在-0.4V时电流密度能达到-230mA·cm-2;当以乙二醇和丙酮的复合溶剂代替去离子水作溶剂,在600℃下制得了钙钛矿型催化剂,催化剂粒径在20-30nm之间,以此产物为催化剂制备的空气电极在-0.4V时电流密度能达到-273mA·cm-2,并优化了其它制备条件。确定了可充空气电极的最佳配方,其中碳载体采用乙炔黑。催化层的最佳配方PTFE:乙炔黑：催化剂质量比为1：1：2,同时添加占催化层总质量16.7%的醋酸铅的造孔剂；防水层的最佳配方为,PTFE:乙炔黑质量比7：3,同时添加占防水层总质量4.7%的醋酸铅作造孔剂；空气电极采取催化层／导电网／防水透气层的结构。研究了可充锌-空气电池的制备工艺,辅助电极采用附钴泡沫镍具有最佳的析氧性能；锌电极集流体采取镀铅铜带能明显降低析氢腐蚀。以此工艺制备的锌-空气电池,在10A恒流放电、5.3A恒流充电的制度下能循环35次。更多还原

【Abstract】 The bifunctional oxygen electrode catalyst is the one of key problem of secondary zinc-air battery. Additionally, the structure of air electrode and zinc electrode have a great influence on zinc-air battery.In this article, the preparation of the catalyst, air electrode and the current collector of zinc electrode were studied and explored systematically. The perovskite type oxides LaNi0.8Co0.2O3 was prepared by the improved sol-gel method. XRD, SEM and TEM were employed to characterize the prepared catalysts.The polarization curves, electrochemical impedence spectroscopy methods and the galvanostatic discharge curves were used to study the electrocatalytic performances of the prepared catalyst in 7 mol/L KOH solution.The perovskite catalyst was prepared by the improved sol-gel method, the graphite was added into precursor by the molar ratio of all metal ion to the graphite was 1:1.The catalyst was prepared under different calcination temperatures, The results showed that the catalyst had the lowest agglomerates and the best electrochemical performance at the calcination temperature of 500℃. The oxygen reduction current density was 230mA·cm-2 at the electrode potential of -0.4V(vs.Hg/HgO). When the solvent was mixed by glycol and acetone instead of deionized water, The catalyst was prepared at the calcination temperature of 600℃, the grain diameter could get to 20-30nm and the oxygen reduction current density was 273mA·cm-2 at the same condition, respectively, a series of factors were considered during preparing process.The best composition of the rechargeable air electrode was established. The acetylene black was applied as the gas diffusion electrode carrier. In the catalysis layer, the best quality ratio of the component of PTFE, acetylene black and catalyst was 1:1:2. When adding 16.7%wt lead acetate as pore forming material, the best quality ratio of PTFE and acetylene black was 7:3 in the waterproof layer, the lead acetate was added in the mass ratio of 4.7% of the waterproof layer. Finally, the component of air electrode were arrayed as catalysis layer/ current collector/waterproof layer.The preparation technology of the rechargeable zinc-air battery was analyzed. The air electrode has the best oxygen evolution property if the foamy nickel as a auxiliary electrode. The lead plating copper as the current collector of zinc electrode can decrease hydrogen corrosion remarkably. The zinc-air battery was fabricated, the discharging and recharging number of the battery attained 35 times when the galvanostatic discharge current was 10A and galvanostatic charge current was 5.3A.更多还原