Compressive Creep of Polymer Electrolyte Membranes: A Case Study for Electrolyzers

Abstract

For proton-exchange membrane (PEM) water electrolyzers to be commercially feasible, PEMs must perform over long lifetimes in liquid environments under compression while maintaining mechanical stability. Hydrated environment, while inherent for operation and conductivity, undermines PEM stability. Mechanical stability of PEMs is commonly characterized in tension, which is not applicable to electrolyzers, wherein PEMs could undergo high pressures. In this study, a compression creep procedure is developed using a custom-designed setup to monitor creep response of hydrated PEMs.Our results show PEMs exhibit continuous creep response under compression over 24 hours, with a dependence on the applied pressure and hydration state.

Recent progress in understanding the catalyst layer in anion exchange membrane electrolyzers – durability, utilization, and integration

“…Such behaviors can occur when surface porosity is too high, especially under H 2 backpressure operation, as has been shown in PEMWEs. 64…”

Membrane Strategies for Water Electrolysis

“…Proton selectivity (ratio of proton conductivity to hydrogen permeability) can be used as an estimated measure of membrane performance. For PFSA-based membranes, having higher IEC (lower equivalent weight) has shown a potential to improve proton selectivity and cell performance of PEMWE (4–6 A cm –2 at 1.85 V) by enhancing proton conductivity but keeping hydrogen permeability unchanged. , However, PFSA PEMs with higher IEC tend to swell, leading to delamination from electrodes and premature creep failure under high compression operation . Proton selectivity of PFSA membranes can be increased without increasing IEC by blending with polymers with low hydrogen permeability.…”

“…Polarization curves of PEMWEs using selected PEMs at 80 °C and ambient pressure. − ,, PEMWE performance using Nafion212 (light gray dash) was shown for comparison purpose. Nafion + GRC cell: anode: IrO 2 (0.4 mg cm –2 ), cathode: Pt/C (0.1 mg –2 ), Aquivion cell: anode: IrRuO (0.4 mg cm –2 ), cathode: Pt/C (0.5 mg cm –2 ), Aquivion ionomeric binder, BPSH cell: anode: IrO 2 (2.0 mg cm –2 ), cathode: Pt/C (0.4 mg cm –2 ), Nafion ionomeric binder, sPPS cell: anode: IrO 2 (1.5 mg cm –2 ), cathode: Pt/C (0.5 mg cm –2 ), ionomeric binder: sPPS.…”

“…14,15 However, PFSA PEMs with higher IEC tend to swell, leading to delamination from electrodes 16 and premature creep failure under high compression operation. 17 Proton selectivity of PFSA membranes can be increased without increasing IEC by blending with polymers with low hydrogen permeability. Electrospun polysulfone (PS)−Aquivion (IEC = 1.2 mequiv g −1 ) has demonstrated 2.6-times higher selectivity than Nafion117 (IEC = 0.9 mequiv g −1 ) with improved performance (2 A cm −2 at 1.76 V at 80 °C) 18 (Figure 4a).…”

Tailoring the Mass Transport to Achieve High-Performing Unitized Regenerative Fuel Cells Considering Practical Operating Conditions

“…Consequently, similar to a water electrolyzer, thick membranes μm) are necessary to provide high mechanical durability and low hydrogen permeation. [42][43][44][45][46][47] On the contrary, thinner membranes (<20 μm) are commonly used to diminish ohmic loss and achieve high performance at high current densities for a fuel cell. As URFCs need to function in both electrolyzer mode for charging and fuel-cell mode for discharging, such a Janus requirement suggests the existence of an optimum membrane thickness that balances cell performance, device longevity, and operational safety.…”