Study on graphite felt electrode
Study on graphite felt electrode for vanadium redox battery
Abstract: Based on the vanadium battery with the surface of graphite felt electrode material modification, focuses on the electrochemical oxidation of graphite felt, discussed the cathode of V (IV) /V (V) reaction mechanism in the graphite felt electrode, the main contents are as follows: first reported the vanadium battery by electrochemical oxidation treatment method of graphite felt electrode. It is found that electrochemical oxidation can greatly improve the electrochemical activity of graphite felt in vanadium batteries. The battery can discharge under 30 mA cm<'-2>, the voltage efficiency can reach to 85%, the current efficiency is about 95%, the charge discharge performance is better than the results obtained by acid and heat treatment, and the circulation performance is stable. The greater the degree of oxidation of the electrode, the electrochemical activity of the better. The electrochemical activation mechanism of graphite felt electrode was studied by X ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), BET/N<, AC impedance and other analytical techniques. XPS and FT-IR analysis showed that the electrochemical treatment mainly increased the O/C ratio and the number of oxygen-containing functional groups in the carbon fiber surface, especially the content of COOH functional groups. SEM and BET/N<, 2> analysis showed that electrochemical oxidation increased the surface area of graphite felt, which increased the electrode reaction area. AC impedance analysis showed that electrochemical oxidation mainly reduces the charge transfer resistance of the electrode reaction process, the increase can be attributed to the surface of COOH modified carbon fiber content, the formation of -C-O-V- bonds, in favor of electron loss with O atoms in VO<'2+> and VO<, 2><'+> transfer. The electrochemical mechanism of V (IV) /V (V) on graphite felt electrode was studied by cyclic voltammetry, polarization curves and electrochemical impedance spectroscopy. Cyclic voltammetry analysis showed that the oxidation reaction of V (IV) to V (V) was a quasi reversible process, and the oxidation process included the step of post chemical conversion. Polarization curves and AC impedance studies show that the charge transfer step may be the controlling step of the whole reaction.
carbon carbon composite, graphite, graphite felt http://www.cfccarbon.com/