Zheng Xiaoying, Mohammadi Naser, Moreno Zuria Alonso, Mohamedi Mohamed
Institut National de la Recherche Scientifique (INRS), Énergie Matériaux Télécommunications (EMT), 1650, Boulevard Lionel-Boulet, Varennes, Québec J3X 1P7, Canada.
ACS Appl Mater Interfaces. 2021 Dec 29;13(51):61374-61385. doi: 10.1021/acsami.1c22371. Epub 2021 Dec 19.
It is today advanced that the development of a free-standing (binderless) air cathode via direct growth of nonprecious metal electrocatalysts onto the surface of the conductive collector would be a cutting-edge strategy to reduce the interfacial resistance, improve the mechanical stability, and reduce the final weight and the cost of manufacturing. Here, for Zn-air batteries (ZABs), we propose an innovative binderless noble-metal-free hierarchical nanostructured bifunctional air cathode in which high-density MnO nanorods (NRs) are directly grown on carbon nanotubes (CNTs) themselves synthesized on a microfibrous carbon paper (CP) substrate. All carbon/MnO air cathodes achieved specific capacities very close to the theoretical value of 820 mAh g. A very stable voltage gap between the charge and discharge processes along hundred cycles was obtained, demonstrating the stability and good bifunctional electrocatalytic activities of these cathodes toward the oxygen reduction reaction/oxygen evolution reaction in a real ZAB device. As a proof-of-concept for handheld electronic applications, a ZAB assembled with CP/MnO NRs as the air electrode and a Zn plate anode operated a timer for 14 days successfully, whereas two ZAB-based CNTs/MnO cathodes connected in series powered a 2 V light-emitting diode (LED) bulb and a 3 V multimeter. The proposed strategy and results may pave the way for the rational design of hierarchical free-standing bifunctional electrocatalysts for ZABs, other metal-air batteries, and fuel cells.
如今有人提出，通过在导电集流体表面直接生长非贵金属电催化剂来开发一种独立式（无粘结剂）空气阴极，将是一种前沿策略，可降低界面电阻、提高机械稳定性，并降低最终重量和制造成本。在此，对于锌空气电池（ZABs），我们提出了一种创新的无粘结剂无贵金属分级纳米结构双功能空气阴极，其中高密度MnO纳米棒（NRs）直接生长在微纤维碳纸（CP）基板上自行合成的碳纳米管（CNTs）上。所有碳/MnO空气阴极的比容量都非常接近820 mAh g的理论值。在数百次循环中，充电和放电过程之间获得了非常稳定的电压间隙，证明了这些阴极在实际ZAB装置中对氧还原反应/析氧反应具有稳定性和良好的双功能电催化活性。作为手持式电子应用的概念验证，一个以CP/MnO NRs作为空气电极和锌板阳极组装的ZAB成功地为一个定时器供电14天，而两个串联的基于ZAB的CNTs/MnO阴极为一个2 V发光二极管（LED）灯泡和一个3 V万用表供电。所提出的策略和结果可能为合理设计用于ZABs、其他金属空气电池和燃料电池的分级独立双功能电催化剂铺平道路。
