Toward Scalable Production: Catalyst‐Coated Membranes (CCMs) for Anion‐Exchange Membrane Water Electrolysis via Direct Bar Coating

Abstract

Direct catalyst coating of membranes is an obvious membrane‐electrode assembly (MEA) fabrication approach. Nevertheless, it bears significant challenges related to excessive swelling of the wetted membranes and catalyst layers during coating. Thermal decaling, which is currently used in proton exchange electrolysis, cannot be used with typical hydrocarbon‐based anion‐exchange membranes due to the lack of a glass transition point. In this work, a novel direct‐coating approach for MEAs for anion‐exchange membrane water electrolysis is proposed. An additional adhesive foil is used to minimize membrane swelling during the coating of the second catalyst layer. The resulting cell efficiency (1 A cm−2 at 1.8 V with ≥ 1.9 mgIr cm−2) is comparable to spray‐coated cells, while the mass transport is reduced at higher current densities (2.11 V vs 2.27 V at 2.7 A cm−2). A fully self‐casted catalyst‐coated membrane with low thickness (35 µm) achieves promising performance of 1.4 A cm−2 at 1.8 V in 0.1 m KOH and 2.0 A cm−2 in 1 m KOH. Constant current holds at 1 A cm−2 in 1 m KOH further shows a comparably low degradation rate of both spray‐ and bar‐coated cells (≈1 mV h−1) after a stabilization period.

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

“…2b) and must be electronically conductive to allow electrons to move between the catalyst particles and the current collectors. It is also important to note that, on the anode side, the transport layer must be able to withstand high potentials (i.e., often up to and exceeding 2 V) and an aqueous, alkaline environment (i.e., pH of [12][13][14]. Common materials for transport layers in AEMWEs include C paper and Ni, Ni alloy, or stainless steel meshes and foams, 21,57,58 although C is not a viable choice for the anode transport layer because it oxidizes and degrades at high potentials and pH.…”

“…43,44 These improvements, alongside advances in catalyst development, have enabled AEMWE cell performances exceeding 3 A cm −2 at reasonable voltages (1.8–2.2 V). 13,14…”

Single atom catalysts for water electrolysis: from catalyst-coated substrate to catalyst-coated membrane

“…37 Subsequently, recognizing the importance of the catalyst/membrane interface, the catalyst-coated membrane (CCM) method was developed, allowing the direct introduction of catalysts onto the membrane. 38–40 This method demonstrates several advantages that position itself as a compelling option for water electrolysis, including low ohmic losses, efficient mass transport, and scalability. Recent studies have highlighted the significant impact of the MEA fabrication method on cell performance and scalability.…”

Key components and design strategy of the membrane electrode assembly for alkaline water electrolysis

“…(c): 1,26 2,180 3,204 4,93 5,205 6,54 7,206 8,86 9,207 10,183 11,74 12,29 13,208 14,181 15,184 16,185 17,186 18,187 19,209 20,36 21,94 22,210 23,188 24,211 25,190 26,191 27 212. (d): 1,26 2,59 3,213 4,214 5,215 6,216 7,217 8,218 9,219 10,147 11,220 12,221 13,222 14,223 15,29 16,67 17,185 18,94 19,224 20,210 21,225 22,226 23,227 24,228 ...…”