Application of Novel Anion-Exchange Blend Membranes (AEBMs) to Vanadium Redox Flow Batteries

Abstract

Both cation-exchange membranes and anion-exchange membranes are used as ion conducting membranes in vanadium redox flow batteries (VRFBs). Anion-exchange membranes (AEMs) are applied in vanadium redox flow batteries due to the high blocking property of vanadium ions via the Donnan exclusion effect. In this study, novel anion-exchange blend membranes (AEBMs) were prepared, characterized, and applied in VRFBs. Bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide), poly[(1-(4,4′-diphenylether)-5-oxybenzimidazole)-benzimidazole] (PBI-OO) and sulfonated polyether sulfone polymer were combined to prepare 3-component AEBMs with 1,2,4,5-tetramethylimidazole (TMIm) for quaternization. 3-component AEBMs showed significantly enhanced chemical and mechanical properties compared with those of 2-component AEBMs, resulting in an improved performance in VRFBs. The compositions of the anion-exchange polymers in 3-component AEBMs were systematically varied to optimize the AEBMs for the redox-flow battery application. While the 3-component AEBMs showed comparable efficiencies with Nafion® 212 membranes, they displayed improved vanadium ions cross-over as was confirmed by open circuit voltage tests and capacity fade tests conducted in VRFBs. In addition, one of the synthesized 3-component AEBM had a superior coulombic efficiency and capacity retention in a charging–discharging test over 300 cycles at a current density of 40 mA/cm2. It can thus be concluded that 3-component AEBMs are promising candidates for long-term operation in VRFBs.

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

“…To evaluate the vanadium redox flow battery performance, a single cell was built as described in the literature [21]. The membrane was placed between two electrodes (active area: 28 cm 2 , SIGRACELL ® Polymers 2020, 12, 915 5 of 14 GDF 4.6 EA, SGL Carbon GmbH, Bonn, Germany,) which were thermally treated at 450 • C for 5 h after immersion in 1 M sulfuric acid for 1 day.…”

“…In order to evaluate the VRFB performance, a single VRFB cell was constructed as described in the literature [21]. It is important to note that all of the measurements were performed without electrolyte circulation, in a stationary mode.…”

“…As seen in Figure 6a, the CEs of blend membranes were higher than that of the Nafion membrane, due to the Donnan exclusion effect as described above, while the Nafion membrane showed a low CE due to increased vanadium cross-over. It should be noted that AEMs do not always show high CEs, as this would also require a high dimensional stability of the membrane [21]. In addition, more dense PBI membranes yielded higher CEs due to the low vanadium ion permeability [34].…”

The Structure–Activity Relationship in Membranes for Vanadium Redox Flow Batteries

“…Various polyketones like poly(ether ether ketone) (PEEK), [89] poly(phthalazinone ether ketone) (PPEK), [90] poly(phthalazinone ether ketone ketone) (PPEKK), [91] poly(aryl ether ketone) (PAEK), [92] cardo-poly(ether ketone) (PEK-C), [93] polysulfones like poly(arylene ether sulfone) (PAES), [94] poly(ether sulfone) (PES), [87,95] polysulfone (PSF or PSU), [96] and poly(phenyl sulfone) (PPSU), [96] polyolefins like Diels Alder poly(phenylene) (DAPP), [97] polyethers like poly(fluorenyl ether) (PFE) [98] and poly (ethylene) (PE), [99] Adv. Various polyketones like poly(ether ether ketone) (PEEK), [89] poly(phthalazinone ether ketone) (PPEK), [90] poly(phthalazinone ether ketone ketone) (PPEKK), [91] poly(aryl ether ketone) (PAEK), [92] cardo-poly(ether ketone) (PEK-C), [93] polysulfones like poly(arylene ether sulfone) (PAES), [94] poly(ether sulfone) (PES), [87,95] polysulfone (PSF or PSU), [96] and poly(phenyl sulfone) (PPSU), [96] polyolefins like Diels Alder poly(phenylene) (DAPP), [97] polyethers like poly(fluorenyl ether) (PFE) [98] and poly (ethylene) (PE), [99] Adv.…”

“…To solve the problems, AEMs with various polymer backbones have been studied for VRFBs. Various polyketones like poly(ether ether ketone) (PEEK), poly(phthalazinone ether ketone) (PPEK), poly(phthalazinone ether ketone ketone) (PPEKK), poly(aryl ether ketone) (PAEK), cardo‐poly(ether ketone) (PEK‐C), polysulfones like poly(arylene ether sulfone) (PAES), poly(ether sulfone) (PES), polysulfone (PSF or PSU), and poly(phenyl sulfone) (PPSU), polyolefins like Diels Alder poly(phenylene) (DAPP), polyethers like poly(fluorenyl ether) (PFE) and poly (ethylene) (PE), and poly(benzimidazole) (PBI)95a,100 have been developed as polymer backbones for VRFBs.…”