Stability of Positive Electrolyte Containing Trishydroxymethyl Aminomethane Additive for Vanadium Redox Flow Battery

Abstract

Trishydroxymethyl aminomethane (Tris) was used as an additive of the positive electrolyte for all vanadium redox battery (VRB) and cycling and electrochemical stabilities of the positive electrolyte were investigated. The 50 cyclic voltammetry (CV) cycles suggested that the positive electrolyte with the Tri additive after charge-discharge cycles has good cycle stability compared to that before the charge-discharge cycles. The VRB employing the vanadium electrolyte with the Tris additive as positive electrolyte exhibited better charge-discharge behavior and less discharge capacity fade rate with cycles compared with the blank electrolyte system. The UV/visible spectroscopy showed that the vanadium concentration in the positive electrolyte containing Tri additive during 40 charge-discharge cycles remains unchanged. The X-ray photoelectron spectroscopy (XPS) verified that the positive electrolyte with the Tri additive has no etching and oxidation effect on the carbon felt electrode.