Composite Anion Exchange Membranes Fabricated by Coating and UV Crosslinking of Low-Cost Precursors Tested in a Redox Flow Battery

This paper presents a novel, cost-effective approach to the fabrication of composite anion exchange membranes (AEMs). Hierarchical AEMs have been fabricated by coating a porous substrate with an interpenetrating polymer network (IPN) layer where poly(vinylpyrrolidone) (PVP) is immobilized in a crosslinked matrix. The IPN matrix was formed by UV initiated radical crosslinking of a mixture of acrylamide-based monomers and acrylic resins. The fabricated membranes have been compared with a commercial material (Fumatech FAP 450) in terms of ionic transport properties and performance in a vanadium redox flow battery (VRFB). Measures of area-specific resistance (ASR) and vanadium permeability for the proposed membranes demonstrated properties approaching the commercial benchmark. These properties could be tuned by changing the content of PVP in the IPN coating. Higher PVP/matrix ratios facilitate a higher water uptake of the coating layer and thus lower ASR (as low as 0.58 Ω.cm2). On the contrary, lower PVP/matrix ratios allow to reduce the water uptake of the coating and hence decrease the vanadium permeability at the cost of a higher ASR (as high as 1.99 Ω.cm2). In VRFB testing the hierarchical membranes enabled to reach energy efficiency comparable with the commercial AEM (PVP_14—74.7%, FAP 450—72.7% at 80 mA.cm−2).

Anion-Exchange Membrane with Poly(3,3’-(hexyl) bis(1-vinylimidazolium) bromide)/PVC Composites Prepared by Inter-polymerization

The advanced anion-exchange membranes with the poly(3,3’-(hexyl)bis(1-vinylimidazolium)bromide), PHVB, was synthesized by inter-polymerization of a 3,3'-(hexyl)bis(1-vinylimidazolium) bromide in poly(vinyl chloride), PVC, solution. We confirmed the successful preparation of the advanced anion-exchange membrane (AEM) such as ionic conductivity (S/cm), water uptake (%), ion-exchange capacity (meq/g), vanadium permeability, thermal properties, and SEM analysis, respectively. The vanadium redox flow battery (VRFB) performances using the prepared AEM based on PHVB/PVC composite polymers in organic electrolytes was examined. In the prepared advanced AEM, the maximum voltages reached 2.5 V under the fixed current value of 0.005mA. The synthesized advanced AEM has also good stability with organic electrolyte by battery performance under 1000 cycles. As results, the advanced AEM based on PHVB/PVC prepared by the inter-polymerization is suitable for use as a battery separator in VRFB.

Novel sulfonated poly(ether ether ketone)/triphenylamine hybrid membrane for vanadium redox flow battery applications

The novel TPAM hybrid membrane exhibited both lower vanadium permeability and higher proton conductivity than pristine SPEEK membrane.