Cross-Linked Poly(vinylbenzyl chloride) Anion Exchange Membranes with Long Flexible Multihead for Fuel Cells

Abstract

To enhance the ionic conductivity and mechanical property of the chemically stable aliphatic anion exchange membranes (AEMs), cross-linked poly­(vinylbenzyl chloride) AEMs (PVBC-xQ4) bearing long flexible cross-linker chains with multiple quaternary ammonium (QA) head were prepared via a facile one-step process. The AEMs exhibit high conductivity and excellent mechanical property. The cross-linked AEMs excluding any other heteroatomic bond especially the sulfone linkage or ether bond in the backbone have robust alkaline stability, low water uptake, and good dimensional stability. A well-developed hydrophilic/hydrophobic phase separated morphology was observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The PVBC-50Q4 membrane with ionic exchange capacity (IEC) of 1.87 mequiv g–1 displays a highest ionic conductivity of 74.3 mS cm–1 at 80 °C. After tested in a 2 M aqueous KOH solution at 80 °C for 1300 h, 88% of the conductivity and 89% of the IEC were remained. Furthermore, a single cell using the PVBC-50Q4 membrane has a maximum peak power density of 109.2 mW cm–2 at 60 °C.

Branched, Side-Chain Grafted Polyarylpiperidine Anion Exchange Membranes for Fuel Cell Application

“…The calculated E a values of qPBPTT-5, qPBPTT-3, qPBPTT-1, and qPBPTT-0 membranes are 13.51, 13.62, 14.73, and 16.71 kJ/mol, respectively, as shown in Figure b. The lowest E a comes from qPBPTT-5, which means that this membrane has the smallest energy barrier for ion transport, again confirming the free volume and microphase separation effects related with the Y-branched membrane structure. , …”

“…To achieve high performance of AEMs, different membrane structures have been designed in the literature via strategies such as cross-linking, , branching, , blending, and block copolymerization. − Meanwhile, the introduction of a bulky, rigid unit can provide free volume to help build ion transport channels in an AEM . In our previous work, we designed an AEM incorporating polymer of intrinsic microporosity (PIM), which showed a higher conductivity (20.7 mS/cm, 25 °C) than that without PIM (15.8 mS/cm, 25 °C) at a lower IEC (0.91 vs 1.13 mmol/g) .…”

Ionic Highways from Covalent Assembly in Highly Conducting and Stable Anion Exchange Membrane Fuel Cells

“…First, we needed to prevent high water uptake and swelling by constructing a cross-linked polymer network. 11,12 We decided installing cations as the cross-linkers would be the preferred strategy, as it balances IEC and mechanical stability. Second, we targeted fully substituted cationic rings to avoid reactive C-H groups.…”

Highly conductive and stable anion‐exchange membranes based on crosslinked poly(arylene ether sulfone)‐block‐poly(phenylene oxide) Networks

“…For example, c‐PES‐5.3‐PPO‐10 possessing the highest IEC (3.76 mmol g −1 ) had relatively low conductivity (70.3 mS cm −1 , 80 °C). It is speculated that long segments are prone to long‐range ordered arrangement in favor of high conductivity . Analogous to the movement of proton in Nafion, hydroxide ion transport in hydrated solid polymer electrolytes via vehicular mechanism and Grotthus mechanism .…”

“…(a) Conductivity, (b) swelling degree, (c) WU of membranes, and (d) relationship of hydroxide conductivity (80 °C) with IEC and SR (80 °C) for the crosslinked AEMs reported recently . [Color figure can be viewed at wileyonlinelibrary.com]…”