Sun Jing, Jiang Haoran, Zhao Chen, Fan Xinzhuang, Chao Christopher, Zhao Tianshou
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China; Institute for Advanced Study, The Hong Kong University of Science and Technology, Hong Kong, China.
Sci Bull (Beijing). 2021 May 15;66(9):904-913. doi: 10.1016/j.scib.2020.12.019. Epub 2020 Dec 16.
Fabricating electrodes with large specific surface area (SSA) and high permeability has been the long-standing target in redox flow batteries (RFBs). In this work, we propose a novel ZIF-8-assisted etching approach to form holey fibers in the electrospinning process of aligned electrode structures. The etching approach allows the formation of holey fibers with small pores of ~50 nm, offering large active surface areas for redox reactions, while the aligned macrostructure with the holey fibers of 3-5 μm in diameter ensures a high permeability along the fiber direction. The application of the prepared electrodes to a vanadium redox flow battery (VRFB) enables an energy efficiency (EE) of 87.2% at the current density of 200 mA cm, which is 13.3% higher than that with conventional electrospun carbon electrodes. Even at high current densities of 300 and 400 mA cm, the battery still maintains energy efficiencies of 83.3% and 79.3%. More excitingly, the prepared electrode yields a high limiting current density of 4500 mA cm and a peak power density of 1.6 W cm. It is anticipated that the present electrospinning method combining the ZIF-8-assisted etching approach with a way to form ordered fiber structures will allow even more high-performance electrodes for RFBs in the future.
制备具有大比表面积（SSA）和高渗透性的电极一直是氧化还原液流电池（RFBs）的长期目标。在这项工作中，我们提出了一种新颖的ZIF-8辅助蚀刻方法，以在排列电极结构的静电纺丝过程中形成多孔纤维。该蚀刻方法允许形成具有约50nm小孔的多孔纤维，为氧化还原反应提供大的活性表面积，而直径为3-5μm的多孔纤维的排列宏观结构确保了沿纤维方向的高渗透性。将制备的电极应用于钒氧化还原液流电池（VRFB），在200mA cm的电流密度下能量效率（EE）达到87.2%，比传统静电纺丝碳电极高13.3%。即使在300和400mA cm的高电流密度下，电池仍保持83.3%和79.3%的能量效率。更令人兴奋的是，制备的电极产生了4500mA cm的高极限电流密度和1.6W cm的峰值功率密度。预计目前将ZIF-8辅助蚀刻方法与形成有序纤维结构的方法相结合的静电纺丝方法未来将为RFBs带来更多高性能电极。
