AEM Update ~ 2024.08.17

Key Component Analysis of Anion Exchange Membrane (AEM) Electrolyzers The anion exchange membrane (AEM) is one of the core components of AEM electrolyzers, serving two primary functions: (1) acting as an internal channel for OH⁻ conduction; and (2) physically separating hydrogen gas generated at the cathode from oxygen gas generated at the anode—thereby preventing hazardous incidents. AEMs play a critical role in determining the overall performance and durability of the electrolyzer. Microstructurally, AEMs typically consist of various cationic functional groups anchored to a polymeric backbone; these cationic groups confer anion selectivity to the membrane. Most commonly, quaternary ammonium groups serve as the cationic moieties, while polymer backbones are often based on poly(arylene ether)s, polystyrene, polysulfone, polyethersulfone, or polyphenylene oxide. Existing research indicates that the polymer backbone structure predominantly governs mechanical strength and thermal stability, whereas the cationic groups primarily influence ion-exchange capacity, ionic conductivity, and transference number. Chemical stability, however, arises from the synergistic interplay between both the backbone and the cationic groups—and thus the overall polymer architecture significantly affects degradation mechanisms and rates. As the most advanced water electrolysis technology today, AEM electrolysis has a relatively short development history, and high-performance AEMs remain in the early exploratory stage. Compared with mature proton exchange membranes (PEMs), AEMs exhibit lower ionic conductivity and inferior chemical stability than perfluorosulfonic acid membranes. In terms of conductivity, OH⁻ transport in AEMs is roughly half as efficient as H⁺ transport in PEMs. Regarding stability, under alkaline conditions and at operating temperatures of 60–80 °C, both the polymer backbone and organic cationic groups are vulnerable to nucleophilic attack by OH⁻ ions, leading to rapid chemical degradation—manifested by sharp declines in mechanical integrity and ionic conductivity. Consequently, the comparatively low ionic conductivity and limited durability of AEMs have remained major obstacles hindering their large-scale commercial deployment. To fully realize the cost advantage of AEM electrolysis technology, developing non-precious-metal catalysts is crucial for reducing system costs. In recent years, extensive efforts have been devoted to developing transition-metal-based oxygen evolution reaction (OER) catalysts for water electrolysis under weakly alkaline conditions. These materials mainly involve first-row transition metals—including nickel (Ni), cobalt (Co), iron (Fe), and copper (Cu)—as well as second-row molybdenum (Mo). Among them, Ni-based OER catalysts demonstrate favorable activity and stability in alkaline media and are widely employed as OER electrocatalysts. Due to its strong oxophilicity, Fe exhibits a pronounced tendency to adsorb OH⁻ species and thus commonly serves as a kinetic promoter for OER. Numerous studies have shown that NiFe-based electrocatalysts possess high intrinsic activity and low energy barriers for intermediate adsorption, rendering them highly promising for weakly alkaline water electrolysis OER applications. Additionally, Co is favored for its relatively low cost and inherent oxidation resistance within the OER potential window. Like Ni-based OER electrocatalysts, it is also widely adopted as a precious-metal alternative. Analogous to the excellent OER performance demonstrated by NiFe-based catalysts, incorporating Fe into Co-based systems to form CoFe-based catalysts likewise yields commendable OER activity.

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R&D Projects Underway in Japan 1. Toyota + Tanaka Kikinzoku Joint Development of Low-Platinum Alloy Catalysts: Supported by NEDO’s ¥10 billion special initiative, the project targets reducing platinum loading to below 0.05 g/kW by 2030. It remains firmly committed to platinum-based catalysts, tightly integrating with Japan’s domestic precious-metal supply chain and maintaining robust material patent barriers. 2. NEDO’s Five-Year Industry–Academia–Research Project (2020–2024): Jointly conducted by Tokyo Institute of Technology and Toyota, this initiative focuses on optimizing Pt–Co alloy catalysts’ resistance to degradation. Cycle-life testing shows a 50% improvement in operational longevity; all underlying fabrication processes remain strictly confidential and undisclosed externally. Chinese Counterpart R&D Cases 1. Research Institutions: The Xing Wei team at Changchun Institute of Applied Chemistry (CIAC), Chinese Academy of Sciences, developed a lanthanum-doped Pt–Co intermetallic catalyst to address the critical issue of platinum-alloy dissolution-induced degradation. Their work was published in the Journal of the American Chemical Society (JACS); on January 26, 2026, CIAC’s official website announced successful pilot-scale validation, achieving platinum loading below 0.1 g/kW. Meanwhile, the Shanghai Advanced Research Institute of CAS developed a novel Pt/C catalyst exhibiting 5.4× higher mass activity than commercial benchmarks, with only 27% activity loss after 20,000 cycles. 2. Industrial Enterprises: Wuhan University of Technology Hydrogen Power launched mass production of its fifth-generation membrane electrode assemblies (MEAs), featuring platinum loading of 0.3 mg/cm², and now supplies domestic commercial vehicle system manufacturers—achieving full localization and substitution of imported catalysts. Guangdong Taiji Power is establishing a pilot line for platinum-free iron-based catalysts, targeting cost-effective heavy-duty commercial vehicles. 4.2 Emerging Proton Exchange Membrane (PEM) Sector R&D Projects Underway in Japan Toyota and Asahi Kasei jointly developed a long-life reinforced perfluorinated PEM, exclusively supplied for the Mirai series. Patents comprehensively cover membrane tear resistance and radical-corrosion resistance. Concurrently, NEDO is advancing high-temperature PEMs (operating at 120 °C), designed solely for compact Japanese passenger-car stacks—membrane formulations and manufacturing processes are not licensed to overseas entities. Chinese Counterpart R&D Cases 1. Shao Zhigang’s team at Dalian Institute of Chemical Physics (DICP), CAS: Developed AEM electrolyzer technology utilizing a dilute-alkaline system, targeting green hydrogen production. A 50-kW AEM electrolyzer stack achieved stable operation for 150 hours without requiring precious-metal catalysts—opening a radically new, low-cost pathway for green hydrogen generation and completely circumventing the perfluorinated PEM patent landscape. 2. Dongyue Group has commenced mass production of domestically manufactured reinforced PEMs, supporting China’s million-unit-per-year MEA production lines and enabling bulk supply of membrane materials for both passenger and commercial vehicles. 4.3 Metal Bipolar Plates Replacing Graphite Bipolar Plates R&D Projects Underway in Japan Toyota’s second-generation Mirai employs proprietary titanium-coated metal bipolar plates, with corrosion-resistant coating processes protected by in-house patents. Accelerated aging tests confirm stable operation for up to 15,000 hours—exclusively supplied for Toyota’s own passenger vehicles. Honda’s FCSM factory operates a metal-bipolar-plate production line tailored for North American passenger vehicles, with coating formulations withheld from external licensing. Chinese Counterpart R&D Cases 1. Enterprise Examples: Xin Yan Hydrogen Energy independently developed its fifth-generation ultra-thin metal bipolar plates, mastering the full suite of proprietary technologies—including stamping, sealing, and anti-corrosion coating processes. Stack costs are reduced by 40% compared with imported Japanese plates, and these plates are now mass-supplied to commercial vehicle systems ranging from 36 kW to 240 kW. Shanghai Hydrogen Morning’s metal-bipolar-plate stack production capacity exceeds 10,000 units annually, with products exported to commercial vehicle markets in Europe and North America. 2. Technical Route Divergence: Japanese metal bipolar plates prioritize extreme miniaturization for passenger cars, whereas domestic Chinese plates relax volumetric constraints, simplify precision machining steps, and optimize for high-volume, low-cost production of heavy-duty trucks.

Asahi Kasei partners with Power to Hydrogen to commercialize AEM electrolysis

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Asahi Kasei and Power to Hydrogen signed an MOU to commercialize anion exchange membrane (AEM) water electrolysis systems for clean hydrogen. The partnership aims to integrate technologies for manufacturing scale-up and support renewable energy integration beyond 2030.

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