A Cost‐effective Nafion Composite Membrane as an Effective Vanadium‐Ion Barrier for Vanadium Redox Flow Batteries

Abstract

Ion exchange membranes play a key role in all vanadium redox flow batteries (VRFBs). The mostly available commercial membrane for VRFBs is Nafion. However, its disadvantages, such as high cost and severe vanadium‐ion permeation, become obstacles for large‐scale energy storage. It is thus crucial to develop an efficient membrane with low permeability of vanadium ions and low cost to promote commercial applications of VRFBs. In this study, graphene oxide (GO) has been employed as an additive to the Nafion 212 matrix and a composite membrane named rN212/GO obtained. The thickness of rN212/GO has been reduced to only 41 μm (compared with 50 μm Nafion 212), which indicates directly lower cost. Meanwhile, rN212/GO shows lower permeability of vanadium ions and area‐specific resistance compared to the Nafion 212 membrane due to the abundant oxygen‐containing functional groups of GO additives. The VRFB cells with the rN212/GO membrane show higher Coulombic efficiencies and lower capacity decay than those of VRFB cells with the Nafion 212 membrane. Therefore, the cost‐effective rN212/GO composite membrane is a promising alternative to suppress migration of vanadium ions across the membrane to set up VRFB cells with better performances.

Advancements of Polyvinylpyrrolidone‐Based Polymer Electrolyte Membranes for Electrochemical Energy Conversion and Storage Devices

“…[69] Therefore, an ion exchange membrane with good conductivity and preferable selective permeability must be selected. [70] Taking the Nafion membrane as an example of the cation exchange membrane, [71] although it has high proton conductivity, there are a lot of negative charges in the membrane, which adversely affects the barrier of vanadium ions (Figure 11a). The positive charge of the anion exchange membrane forms a Donnan repulsion effect with vanadium ions, [72] which makes the membrane have lower vanadium ion penetration, but the proton conductivity of the anion exchange membrane is generally low (Figure 11b).…”

Application of Nanomaterials in Aqueous Redox Flow Batteries

“…To explore more advanced membrane, the thin Nafion/GO composite membrane was developed [72] . Though the thickness was decreased, the Nafion/GO composite membrane showed good vanadium ion permeability owing to the blocking effects of GO.…”

Synthesis and Characterization of Poly(5’‐hexyloxy‐1’,4‐biphenyl)‐b‐poly(2’,4’‐bispropoxysulfonate‐1’,4‐biphenyl) with High Ion Exchange Capacity for Proton Exchange Membrane Fuel Cell Applications

“…Therefore, PEM is important for the overall performances of fuel cell. At present, the most commonly used membrane is NAFION, which is a perfluorosulfonic acid membrane composed of hydrophobic fluorocarbon backbones and hydrophilic sulfonic acid side chains [3] . In the hydrated state, it has excellent mechanical and thermal stability and high proton conductivity because of the nanophase separation morphology formed by the hydrophobic backbone and hydrophilic side chains [4] .…”