PNNL

Abstract

Herein, we found that a new gel polymer interface (GPI) with a large amount of amino and carboxylic acid groups introduced between positive electrode and membrane acts as a key role to prevent the diffusion of vanadium ions across the membrane leading to a severe capacity loss in vanadium redox-flow batteries (VRFBs) over long-term cycling and improving the surface wettability of carbon felt for better reduction and oxidation reactions. XPS and 1H NMR spectra demonstrated that the cross-linked GPI is chemically stable without dissolution of polymers and swellable in the strong acidic electrolytes for 100 cycles. ICP-MS, FT-IR and EDX results proved that the GPI in the electrolytes keeps the concentration of VO2+ as a reversible redox-active species in catholyte, resulting in improved cycling stability due to its functionality to prevent the diffusion of active species across the membrane and stabilize the oxidation states of active species