Zhao Yunhe, Li Yang, Ihsan-Ul-Haq Muhammad, Mubarak Nauman, Xu Mengyang, Qin Xianying, Zhao Tian-Shou, Kim Jang-Kyo
Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, P. R. China.
Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, P. R. China.
Nanoscale. 2022 Apr 14;14(15):5804-5813. doi: 10.1039/d1nr08376g.
The electrochemical performance of carbon nanofiber (CNF) electrodes in vanadium redox flow batteries (VRFBs) is enhanced by optimizing the morphological and physical properties of low-cost electrospun CNFs. The surface area, porosity and electrical conductivity of CNFs are tailored by modifying the precursor composition, especially the sacrificing agent, Fe(acac), in the polymer precursor and carbonization temperature. A highly porous structure with a large surface area is generated by the catalytic growth of graphitic carbon spheres surrounding the iron nanoparticles which are removed by an acid etching process. The graphitic carbon layers formed at a high carbonization temperature improve the electrical conductivity of CNFs. The large surface area of 349 m g together with the abundant mesopore-dominant structure leads to high wettability and high activity for redox reactions of the electrode, giving rise to enhanced electrochemical performance in VRFBs. It delivers an energy efficiency (EE) of 91.4% at a current density of 20 mA cm and 79.3% at 100 mA cm, and maintains an average EE of 72.5% after 500 charge/discharge cycles at 100 mA cm.
通过优化低成本电纺碳纳米纤维（CNF）的形态和物理性能，可提高其在钒氧化还原液流电池（VRFB）中的电化学性能。通过改变前驱体组成，特别是聚合物前驱体中的牺牲剂乙酰丙酮铁（Fe(acac)）和碳化温度，可对CNF的表面积、孔隙率和电导率进行调整。围绕铁纳米颗粒的石墨碳球的催化生长产生了具有大表面积的高度多孔结构，这些铁纳米颗粒通过酸蚀刻工艺被去除。在高温碳化温度下形成的石墨碳层提高了CNF的电导率。349 m²/g的大表面积以及以中孔为主的丰富结构导致电极具有高润湿性和高氧化还原反应活性，从而提高了VRFB中的电化学性能。在20 mA/cm²的电流密度下，其能量效率（EE）为91.4%，在100 mA/cm²时为79.3%，并且在100 mA/cm²下经过500次充放电循环后，平均EE保持在72.5%。
