Performances of Anion-Exchange Blend Membranes on Vanadium Redox Flow Batteries

Abstract

Anion exchange blend membranes (AEBMs) were prepared for use in Vanadium Redox Flow Batteries (VRFBs). These AEBMs consisted of 3 polymer components. Firstly, PBI-OO (nonfluorinated PBI) or F6-PBI (partially fluorinated PBI) were used as a matrix polymer. The second polymer, a bromomethylated PPO, was quaternized with 1,2,4,5-tetramethylimidazole (TMIm) which provided the anion exchange sites. Thirdly, a partially fluorinated polyether or a non-fluorinated poly (ether sulfone) was used as an ionical cross-linker. While the AEBMs were prepared with different combinations of the blend polymers, the same weight ratios of the three components were used. The AEBMs showed similar membrane properties such as ion exchange capacity, dimensional stability and thermal stability. For the VRFB application, comparable or better energy efficiencies were obtained when using the AEBMs compared to the commercial membranes included in this study, that is, Nafion (cation exchange membrane) and FAP 450 (anion exchange membrane). One of the blend membranes showed no capacity decay during a charge-discharge cycles test for 550 cycles run at 40 mA/cm2 indicating superior performance compared to the commercial membranes tested.

Novel Anion Exchange Membrane Based on Poly(Pentafluorostyrene) Substituted with Mercaptotetrazole Pendant Groups and Its Blend with Polybenzimidazole for Vanadium Redox Flow Battery Applications

“…Width Thickness The IECs of the blend membranes were relatively low (up to 1.6 mmol/g) as compared to other published results, due to the low DOS [29,30]. Accordingly, the blend membranes showed low chloride conductivities of 0.043 and 0.038 mS/cm for M-PPFSt-Me 3 and M-PPFSt-Me 4, respectively, measured in 1 M sodium chloride solution.…”

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

“…Selected membranes were tested in VRFB cycling experiments. This RFB system was selected due to vast literature available for performance comparisons [ 13 , 33 , 56 , 57 ]. Two membranes having an opposite combination of properties were studied: moderate ASR-low vanadium permeability (sample PVP_8%) and low ASR–moderate vanadium permeability (sample PVP_14%).…”

H+-Conducting Aromatic Multiblock Copolymer and Blend Membranes and Their Application in PEM Electrolysis

“…Before characterization, the membranes (MBI and 3 CBM) were post-treated for 48 h in 10 vol% hydrochloric acid at 90 • C, followed by a post-treatment in deionized water at 90 • C for 24 h to remove excess acid. The dry and wet weight of the membranes was determined as described in [43]. The water uptake (WU) was calculated using Equation (1) Determination of the ion-exchange capacities (IEC direct and IEC total in mmol SO 3 H/g polymer or membrane) was performed by acid-base titration as described earlier [45].…”