Surface Treatment with CO2 to Improve Electrochemical Characteristics of Carbon Felt Electrode for VRFB

Abstract

<p>The carbon felt is usually hired as electrodes for vanadium redox flow battery (VRFB). In the study, surface modification of carbon felt under CO<sub>2</sub> atmosphere with variables of operating various temperature ranges between 700<italic>°C</italic> and 900<italic>°C</italic>. The qualitative and quantitative analysis were carried out such as scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) to observe degree of surface modification. Result of XPS analysis confirmed increase of carbon and oxidation functional group on the surface with increase of temperature. SEM image was discovered similar phenomena. Electrochemical characteristics such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) revealed the improved electrode performance with increase of temperature. However, the electrochemical performance under treatments temperature of 900<italic>°C</italic> was less than that of under treatment temperature of 850<italic>°C</italic> due to weight loss at the treatment temperature of 900<italic>°C</italic>. From the CV and EIS results, the best electrochemical characteristics was at the temperature of 850<italic>°C</italic>. That of at the temperature of 900<italic>°C</italic> was decreased due to weight loss. The energy efficiencies (EE) obtained from full cell test were 69.37, 80.76, 82.45, and 75.47%, at the temperature of 700, 800, 850, and 900<italic>°C</italic>, respectively.</p>