Why Electrode Materials Are the Core Bottleneck — and Why Filing Activity Reflects That

Annual filings in the alkaline water electrolysis and green hydrogen patent space held steady at under 420 patent families per year through 2020, then accelerated sharply: 850 families in 2021, 1,294 in 2022, and a peak of 1,320 in 2023. The 2024 and 2025 figures — 1,237 and 834 respectively — should be read as understated given the standard 18-to-24-month publication lag for patent applications. The 135% growth rate across the recent period confirms that the lifecycle stage remains Growth, not maturation. The filing surge tracks directly with sovereign industrial-policy commitments to green hydrogen and with electrolyzer manufacturers moving from pilot to commercial scale, creating urgent IP positioning pressure across the supply chain.

The technology composition of the corpus makes the engineering bottleneck legible. The C25B (electrolytic production) branch accounts for 6,631 patent records — dwarfing every other category and reflecting the centrality of cell architecture, membrane configuration, and electrode design to the whole field. The next largest branches are H01M (batteries, cells, and fuel cells) at 1,166 records, C01B (inorganic compounds) at 778 records, B01J (catalysis and chemical processes) at 640 records, and B01D (separation and filtration) at 633 records. The relative thinness of the catalysis and inorganic-compound branches compared to C25B is notable: it indicates that while electrolytic cell engineering has been intensively patented, the specific catalyst chemistries that would enable noble metal-free operation at industrial current densities remain a comparatively less-claimed space — a pattern consistent with the technical difficulty Rheinmetall’s E²ngel project was designed to address. Polymer and coating-related branches (C08J, C23C) also appear, reflecting ongoing work on membrane and surface treatments that accompany electrode innovation.

Three Technology Themes Driving the Alkaline Electrolysis Patent Landscape

Across 7,064 patent families, three overlapping technical contests define where IP value is being created and where the next competitive advantage is likely to emerge.

Who Holds the IP: Applicant Rankings, Momentum, and Geography

De Nora Permelec Ltd leads the alkaline electrolysis patent landscape with 341 patent families — a position that reflects the company’s multi-decade focus on industrial electrode manufacturing. Asahi Kasei Kogyo Kabushiki Kaisha follows with 266 families, and Industrie De Nora SpA (the Italian parent entity) holds a further 218 families, meaning the De Nora group’s combined IP footprint across its entities is substantial. Thyssenkrupp Uhde Chlorine Engineers GmbH registers 181 families, and UOP LLC accounts for 180 families. Together, the top five filers represent 24% of the hundred largest filers in this space. The presence of an industrial chemicals licensor (UOP LLC) and an electrolyzer equipment manufacturer (Thyssenkrupp Uhde) alongside electrode specialists signals that the IP battleground spans the full system stack, not just individual components.

Momentum data reveals a more dynamic picture beneath the aggregate rankings. Industrie De Nora SpA has filed 132 patent families in the most recent period at a rate approximately 4.0 times its prior three-year average — the strongest acceleration in the cohort. Thyssenkrupp Uhde Chlorine Engineers GmbH and UOP LLC show similar step-changes, at 3.2x and 3.4x their prior baselines respectively, with 125 families each in the recent window. Siemens Energy Global GmbH & Co KG, which holds 147 total families, appears in the momentum data as a new entrant with 111 recent families — indicating that a major energy engineering group has rapidly built a material position in this space. By contrast, De Nora Permelec Ltd’s recent filings are down 68% from its prior rate, and Kawasaki Jukogyo KK shows an 86% decline — suggesting these incumbents may be consolidating or broadening their prosecution elsewhere while newer and re-energized entrants close the gap.

Co-filing patterns reveal a dense collaboration network centered on De Nora Permelec Ltd and Yokohama National University, which have co-filed 139 patent families — the most active pairing in the corpus. De Nora Permelec Ltd and Kawasaki Jukogyo KK account for 98 co-filings, and Yokohama National University and Kawasaki Jukogyo KK have jointly filed 55 families, forming a triangular cluster of industrial-academic cooperation. Yokohama National University and Kyoto University have co-filed 38 families, and De Nora Permelec Ltd and Kyoto University have 35 co-filings, extending the academic network. Agfa-Gevaert NV and Vito (the Flemish Institute for Technological Research) account for 27 co-filings, representing a separate European materials-science pairing. These co-filing relationships reflect publicly visible joint prosecution activity only; no further organizational relationship between these entities is stated in the evidence.

Geographically, the United States leads with 1,481 patent records, followed closely by Europe via the EPO at 1,441 records and China at 1,331 records. WIPO PCT filings total 1,011 records, indicating broad international prosecution strategies. Australia (618 records) and India (448 records) are notable secondary jurisdictions — consistent with both countries’ stated ambitions as green hydrogen export hubs. Canada (444 records), Japan (275 records), and Germany (196 records) complete the major filing destinations. The geographic spread across both established industrial economies and potential hydrogen-exporting nations indicates that applicants are pursuing global enforcement positions, not just home-market protection.

Foundational and most-cited patents

The most-cited filings in scope anchor the field; citation counts accrue over time, so this list favours older, broadly-cited work. Open any row to see it in Eureka.

Strategic Implications for IP and R&D Teams

• Electrode catalyst IP is the highest-leverage filing target. With C25B dominating at 6,631 records but the catalysis branch (B01J, 640 records) comparatively thin, noble metal-free catalyst formulations at the intersection of electrochemical engineering and inorganic chemistry represent the most patent-sparse territory relative to technical and commercial importance. R&D teams developing platinum-free or iridium-free electrode systems should audit freedom-to-operate carefully in C25B while actively building positions in B01J and C01B.
• Newcomers are accelerating; incumbent position is not static. Siemens Energy Global GmbH & Co KG appears as a new entrant in recent filing data with 111 families, and Industrie De Nora SpA and Thyssenkrupp Uhde Chlorine Engineers GmbH have both filed at multiples of their prior three-year rates. IP strategists should treat the landscape as actively contested at the system-integration level, not just at the electrode component level.
• Academic co-filing clusters signal where early-stage IP is forming. The 139 co-filings between De Nora Permelec Ltd and Yokohama National University, and the broader triangular cluster including Kawasaki Jukogyo KK (98 co-filings with De Nora Permelec Ltd) and Kyoto University, indicate that university-industry joint prosecution is a primary route by which fundamental materials science enters the commercial IP estate. Competitive-intelligence teams should monitor academic publications and patent applications from these institutions as leading indicators of next-generation electrode chemistry.
• Downstream processing and storage IP is comparatively underdeveloped. Filing volumes in F17C (84 records) and related storage and compression branches are low relative to upstream electrolysis IP. As projects scale toward multi-megawatt capacities, integrated IP positions covering both production and downstream handling are likely to become differentiating assets — a gap that new entrants could exploit.