AC impedance of influence of glycerin on all vanadium redox flow battery anodic electrolyte

Electrochemical impedance spectrum (EIS) was employed to investigate the mechanism of electrode reaction in anodic electrolyte of vanadium redox battery with additive of glycerin. The spectrums were simulated through the equivalent circuit of RS(Cd(RpW)), and the results show that with the increase of the content of glycerin, the values of RS (the solution resistance), Cd (the double electric layer capacitor) and Rp (the polarization resistance) reach their minimum with 1% glycerin and the concentration polarization reaches its maximum with 1% glycerin. It indicates glycerin containing electron-donating group has effectively promoted the vanadium ion dispersed in solution, so that the solution resistance decreases. When the vanadium ions combining with the glycerin, the increase of molecule volume results in the distance of double electric layer increase, which leads to the decrease of the value of double electric layer capacitor. The adsorption of vanadium ions on electrode surface has been enhanced by added glycerin in anodic electrolyte so as to increase redox catalyst efficiency of anodic electrolyte. Because of the increase of electrode reaction, relative concentration difference between the vanadium ions in solutions and on the surface of electrode has become wider. © All Rights Reserved.