Fabrication and characterization of GA-crosslinked PBI/PVA blend membranes with polydopamine surface modification for alkaline water electrolysis applications

초록

The membrane used in alkaline water electrolysis systems has performance limitations due to the trade-off between ionic conductivity and durability in alkaline environments. To address this limitation, a polybenzimidazole/poly (vinyl alcohol) (PBI/PVA) blend-based ion-solvating membrane was fabricated, then chemically crosslinked with glutaraldehyde (GA) and surface-modified with polydopamine (PDA). FT-IR, XPS, and SEM analyses were conducted to characterize the chemical structure and morphological changes of the fabricated membranes. Swelling behavior, hydroxide-ion conductivity, alkaline stability, and single-cell performance in alkaline water electrolysis were also evaluated. The results showed that GA crosslinking formed a dense polymer network, thereby improving the membrane's mechanical and dimensional stability. In addition, hydrophilic functional groups were introduced through PDA surface modification, enhancing interfacial affinity for the electrolyte. The optimal PBI-PVA-4-C-PDA membrane exhibited the lowest electrical resistance of 2145.97 S2, corresponding to a hydroxide-ion conductivity of 50.12 mS cm-1 , and achieved the highest current density of 337.53 mA cm-2 at 2.0 V in a single-cell test conducted at 60 degrees C in 30 wt% KOH. These results demonstrate that combining chemical crosslinking with PDA surface modification is an effective strategy for alleviating the trade-off between stability and ionic conductivity and for developing high-performance ion-solvating membranes for alkaline water electrolysis.

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