State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Environmental Science and Engineering, Donghua University, 2999 Ren'min North Road, Shanghai 201620, China.
Nanoscale. 2018 Jul 19;10(28):13626-13637. doi: 10.1039/c8nr03162b.
Central to commercializing metal-air batteries is the development of highly efficient and stable catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, a composite catalyst with a unique interpenetrating network (denoted as NiCo2O4@MnO2-CNTs-3) was synthesized and exhibited better bifunctional activity (ΔE = 0.87 V) and durability than both Pt/C and Ir/C catalysts. The improved performance arises from three factors: (i) MnO2 promotes the ORR while NiCo2O4 facilitates the OER; (ii) carbon nanotubes improve the electronic conductivity; and (iii) the highly porous structure enables the adsorption-desorption of O2 and enhances the structural stability. As a result, the primary and rechargeable Zn-air battery affords a high power density and specific capacity (722 mA h g-1), an outstanding discharge stability (255 mW cm-2 after 1000 cycles) and a high cycling stability (over 2280 cycles). Electron microscopy and electrochemical analysis revealed that the degradation of the rechargeable Zn-air battery performance resulted from the damage of the air electrode and the hydrogen evolution reaction on the zinc electrode. A flexible Zn-air battery employing a solid-state electrolyte showed an exciting stability (540 cycles) and high power density (85.9 mW cm-2), suggesting that the anion exchange membrane effectively prevents the migration of Zn2+ ions and the deposition of carbonates.
商业化金属空气电池的核心是开发高效稳定的氧还原反应（ORR）和氧析出反应（OER）催化剂。在这项研究中，合成了一种具有独特互穿网络的复合催化剂（表示为 NiCo2O4@MnO2-CNTs-3），其比 Pt/C 和 Ir/C 催化剂具有更好的双功能活性（ΔE = 0.87 V）和耐久性。性能的提高源于三个因素：（i）MnO2 促进 ORR，而 NiCo2O4 促进 OER；（ii）碳纳米管提高了电子导电性；（iii）高度多孔的结构使 O2 的吸附-解吸成为可能，并增强了结构稳定性。结果，一次和可充电锌空气电池提供了高的功率密度和比容量（722 mA h g-1）、出色的放电稳定性（在 1000 次循环后为 255 mW cm-2）和高的循环稳定性（超过 2280 次循环）。电子显微镜和电化学分析表明，可充电锌空气电池性能的下降是由于空气电极的损坏和锌电极上的析氢反应造成的。采用固态电解质的柔性锌空气电池表现出令人兴奋的稳定性（540 次循环）和高功率密度（85.9 mW cm-2），这表明阴离子交换膜有效地阻止了 Zn2+离子的迁移和碳酸盐的沉积。
