A Zirfon-type membrane based on exfoliated layered double hydroxide for advanced alkaline water electrolysis

Abstract

Large scale hydrogen production using clear and sustainable energy demands advanced alkaline water electrolysis (AWE) with high energy efficiency and good adaptation to fluctuating load. This would require the separator membrane in the electrolyzer to be more ion-conductive and more resistant to gas-crossover than the present commercially available, e.g. Zirfon, membranes. Herein, we report a membrane of exfoliated layered double hydroxide (LDH) bonded by polysulfone. The LDH-based membrane shows an area specific resistance of less than 50 mΩ cm², more than 50 % lower than Zirfon UTP 500, in 30 wt% KOH solution at 80 °C. While the H₂ permeability of the LDH-based membrane is 8.9 × 10⁻⁹ L cm cm⁻² s⁻¹, an order of magnitude lower than that of Zirfon UTP 500. The LDH-based membrane in water electrolysis enables a current density of 1 A cm⁻² at 1.75 V in 30 wt% KOH solution at 80 °C, outperforming Zirfon UTP 500 by 58 mV. Notably, the membrane with up to 90 wt% LDH nanosheets (LNS) is fabricated using industrially viable phase inversion method, enabling straightforward mass manufacturability.