将石墨(GP)和多壁碳纳米管(MWNT)按不同比例压片制成电极, 用于全钒氧化还原液流电池电极材料, 通过循环伏安、交流阻抗、充放电测试、SEM手段对MWNT-GP复合电极进行表征和分析. 研究结果表明, MWNT含量为15wt%的MWNT-GP复合电极性能最佳, 对组装成的静态电池在电流密度20~80 mA/cm2进行充放电性能比较, 电流效率均在93%以上, 电压效率随着电流密度的增加而有所下降.
Electrodes were prepared by mixture of graphite powder (GP) and multi-walled carbon nanotubes (MWNT) at various ratios for all-vanadium redox flow battery. In this studies, the surface morphologies of the composite electrodes were characterized by scanning electron microscope (SEM), and electrochemical behaviors were investigated by cyclic voltammograms, impedance spectroscope and charge-discharge technique. SEM observation shows that the electrode surface roughness increases after adding MWNT to GP. The research results indicate that the MWNT added into GP can provide good electron conductive network between the GP particles, which results in a shorter current conducting pathway in the sheet GP and also a lower internal resistance for the electrodes. The best composition for the positive electrode of all-vanadium redox flow battery (VRB) with different content of MWNT is 15wt%. The current efficiency of VRB using 15wt% MWNT-GP composite electrode is above 93% and the voltage efficiency decrease with current densities increasing under current densities of 20?80 mA/cm2. The improvement in the electrochemical activity of 15wt% MWNT-GP composite electrode is ascribed to the decrease in the total resistivity of vanadium ions adsorption and desorption from MWNT-GP composite electrode and the charge transfer resistivity of MWNT-GP electrode at the electrolyte/electrode interface.
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