Sakthivel Mariappan, Batchu Sai Praneet, Shah Abbas Ali, Kim Kwangmin, Peters Willi, Drillet Jean-Francois
DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main, Germany.
Materials (Basel). 2020 Jul 3;13(13):2975. doi: 10.3390/ma13132975.
Due to the feasibility of an electrically rechargeable zinc/air cell made of a zinc foil as active material, an aqueous choline acetate (ChAcO) mixture as an electrolyte and a spinel MnCoO (MCO) and NiCoO (NCO) as a bi-functional oxygen catalyst was investigated in this work. The 30 wt.% water-containing aqueous ChAcO solution showed high contact angles close to those of KOH favoring triple-phase boundary formation in the gas diffusion electrode. Conductivity and pH value of 30 wt.% HO/ChAcO amounted to 5.9 mS cm and 10.8, respectively. Best results in terms of reversible capacity and longevity of zinc/air cell were yielded during 100 h charge/discharge with the MnCoO (MCO) air electrode polarization procedure at 100 µA cm (2.8 mA g). The corresponding reversible capacity amounted to 25.4 mAh (28% depth of discharge (DOD)) and the energy efficiency ranged from 29-54% during the first and seventh cycle within a 1500 h polarization period. Maximum active material utilization of zinc foil at 100 µA cm was determined to 38.1 mAh (42% DOD) whereas a further charging step was not possible due to irreversible passivation of the zinc foil surface. A special side-by-side optical cell was used to identify reaction products of the zinc/air system during a single discharge step in aqueous ChAcO that were identified as Zn(OH) and ZnO by Raman analysis while no carbonate was detected.
由于采用锌箔作为活性材料、醋酸胆碱（ChAcO）水溶液混合物作为电解质以及尖晶石型锰钴氧化物（MCO）和镍钴氧化物（NCO）作为双功能氧催化剂制成的可充电锌空气电池具有可行性，因此在本工作中对其进行了研究。含30 wt.%水的醋酸胆碱水溶液显示出与氢氧化钾相近的高接触角，有利于在气体扩散电极中形成三相边界。30 wt.% H₂O/ChAcO的电导率和pH值分别为5.9 mS cm⁻¹和10.8。在100 μA cm⁻²（2.8 mA g⁻¹）的电流密度下，采用锰钴氧化物（MCO）空气电极极化程序进行100小时充放电时，锌空气电池在可逆容量和寿命方面取得了最佳结果。相应的可逆容量为25.4 mAh（放电深度（DOD）为28%），在1500小时极化周期内的第一个和第七个循环中，能量效率在29%至54%之间。在100 μA cm⁻²的电流密度下，锌箔的最大活性材料利用率为38.1 mAh（DOD为42%），然而由于锌箔表面的不可逆钝化，无法进行进一步的充电步骤。在醋酸胆碱水溶液中进行单次放电步骤时，使用了一种特殊的并排光学电池来识别锌空气系统的反应产物，通过拉曼分析确定其为氢氧化锌和氧化锌，未检测到碳酸盐。
