Alkaline Diaphragm / AEM Electrolysis Patent Landscape
The alkaline diaphragm and AEM electrolysis patent space comprises 608 patent families and is in a growth phase, with three-year filing volume up 228% versus the prior period, though annual output has eased from its 2023 peak. Activity is moderately concentrated among a Japanese-European industrial core, with Asahi Kasei holding the leading position and a tight cluster of electrolyser and membrane specialists immediately behind.
Asahi Kasei leads a moderately concentrated field with a strong industrial core
Asahi Kasei holds the top position with 68 patent families, ahead of Kawasaki Heavy Industries (54), De Nora Permelec (53), Agfa-Gevaert (51), and Nippon Shokubai (39). The top five filers account for 37% of the combined output of the hundred largest filers, indicating moderate but meaningful concentration.
The tier gap between the first-ranked applicant and the second is relatively narrow — just 14 patent families — suggesting that the leadership position is contestable. The top four applicants are separated by fewer than 20 families, forming a tightly bunched leading cluster rather than a clear monopoly.
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 1 | Asahi Kasei Corporation | 68 | |
| 2 | Kawasaki Heavy Industries, Ltd. | 54 | |
| 3 | De Nora Permelec Ltd. | 53 | |
| 4 | Agfa-Gevaert NV | 51 | |
| 5 | Nippon Shokubai Co., Ltd. | 39 | |
| 6 | ThyssenKrupp Uhde Chlorine Engineers (Japan) Ltd. | 31 | |
| 7 | ThyssenKrupp Uhde Chlorine Engineers GmbH | 29 | |
| 8 | Tokuyama Corporation | 27 | |
| 9 | Yokohama National University | 21 | |
| 10 | Stiesdal Hydrogen A/S | 15 |
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 11 | Industrie De Nora S.p.A. | 14 | |
| 12 | Richards, William R. | 13 | |
| 13 | Tsinghua University | 13 | |
| 14 | Cameron Health Inc. | 12 | |
| 15 | LUT University | 9 | |
| 16 | Nitto Denko Corporation | 9 | |
| 17 | Huaneng Clean Energy Research Institute | 8 | |
| 18 | ABB (Switzerland) AG | 8 | |
| 19 | Beijing University of Chemical Technology | 8 | |
| 20 | Volker, Alan L. | 7 |
The dominance of established Japanese chemical and electrolyser manufacturers, alongside European specialty-materials firms, reflects the technology’s roots in industrial chlor-alkali and water-electrolysis engineering. This incumbency creates a high IP density around core diaphragm cell configurations that new entrants must design around.
The most recent 18–24 months of filing data are subject to publication lag and likely undercount actual activity; conclusions about very recent momentum should be treated as provisional. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Multi-year growth is strong; electrolytic production dominates the technology mix
Two complementary views — annual filing trend and IPC technology composition — reveal both the pace of field expansion and the structural concentration of innovation around electrolytic cell design.
Annual filing trend
Annual filings rose sharply from 18 families in 2017 to a peak of 129 in 2023, representing the core of a 228% multi-year growth surge. Volume eased to 95 in 2024 and the 2025–2026 figures reflect publication lag rather than any confirmed reversal; the multi-year trajectory remains strongly positive.
↗ Hover for values · click a bar to ask EurekaTechnology composition
C25B (electrolytic production of compounds) dominates the IPC mix by a large margin, confirming that diaphragm and membrane design for electrolysers is the primary innovation axis. Secondary branches — C08J (polymer processing), H01M (batteries and fuel cells), and B01D (separation processes) — each account for a small share, signalling adjacent but underdeveloped innovation threads.
↗ Hover for values · click a bar to ask EurekaHighly cited patent families surfaced by the query
Citation-heavy patent families returned by the query. Use this section as citation context, not as a curated list of the most topic-specific patents.
Electrolysis system for hydrogen production and ca…
An electrochemical reactor for capturing carbon dioxide and producing bicarbonate and hydrogen is described herein. The electrochemical reactor is useful for, among other things, converting biogas to a bicarbonate and hydrogen feedstock for biomethanation. The reactor comprises at least one reactor unit comprising an electrolyzer cell and at least one… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Ion permeable diaphragm | 87 |
| 2 | Diaphragm for alkaline water electrolysis and alka… | 78 |
| 3 | Diaphragm for alkaline water electrolysis, alkalin… | 60 |
| 4 | Diaphragm for alkaline water electrolysis and meth… | 54 |
| 5 | Diaphragm for alkaline water electrolysis, and met… | 44 |
| 6 | Diaphragm for alkaline water electrolysis, method … | 42 |
| 7 | Diaphragm for alkaline water electrolysis, alkalin… | 36 |
| 8 | Diaphragm for alkaline water electrolysis and meth… | 36 |
Ranked by total forward citations. Citation counts favour older and broadly cited patent families, and broad or adjacent patents may appear when they match the search scope. Treat this section as citation context, not as a curated list of the most topic-specific patents. Some patent titles may be shown in their original, non-English language where an accurate translation could not be guaranteed.
What the structure means for R&D investment decisions
The combination of a growth-phase trajectory, moderate incumbent concentration, and active multi-party collaboration defines a field where both incumbents and well-positioned challengers can carve out defensible positions.
Growth phase — expanding on a multi-year basis from a 2023 peak
The field is classified as Growth, driven by a 228% increase in three-year filing volume versus the prior three-year window. Annual volume peaked in 2023 at 129 families and has eased since, though publication lag means recent years are understated. The overall trajectory remains expansionary, consistent with green-hydrogen policy tailwinds accelerating commercialisation of AEM and improved alkaline diaphragm systems.
Growth stageModerate concentration with a contestable top tier
The top five filers hold 37% of the hundred largest filers’ combined output — meaningful concentration but not a dominant-player lock-in. The narrow gap between the first and fourth ranked applicants (68 vs 51 patent families) means the leading position is within reach of a focused programme. Chinese universities and start-ups are entering the ranking, signalling a broadening competitive base that could compress incumbents’ lead over time.
Moderate concentrationA dense Japanese co-filing network anchors the ecosystem
The most active co-filing pairs are Kawasaki Heavy Industries with De Nora Permelec (42 joint families) and Kawasaki Heavy Industries with ThyssenKrupp Uhde Chlorine Engineers (Japan) (28 joint families). De Nora Permelec also collaborates with Yokohama National University (16 joint families), bridging industrial and academic research. These alliances cluster around cell-assembly and electrode-diaphragm integration, suggesting that key system-level IP is jointly held and harder to replicate unilaterally.
Alliance-drivenChina leads filing volume; Europe and Japan hold deep prior-art bases
China accounts for the largest share of patent records among jurisdictions, followed by Europe (EPO) and WIPO (PCT). Japan and the United States are tied for fourth. Australia, India, and Canada show meaningful secondary coverage, reflecting global commercial interest in electrolyser deployment. The PCT route is well-used, consistent with applicants seeking broad multi-jurisdictional protection for platform membrane technologies.
China-led, global reachGo beyond the landscape: Eureka’s TRIZ Solution agent breaks down an R&D problem and returns patented concept solutions, each with a technical approach and cited patent & literature evidence.
| Applicant | Collaborator | Co-filings |
|---|---|---|
| Kawasaki Heavy Industries, Ltd. | De Nora Permelec Ltd. | 42 |
| Kawasaki Heavy Industries, Ltd. | ThyssenKrupp Uhde Chlorine Engineers (Japan) Ltd. | 28 |
| De Nora Permelec Ltd. | ThyssenKrupp Uhde Chlorine Engineers (Japan) Ltd. | 18 |
| De Nora Permelec Ltd. | Yokohama National University | 16 |
| Kawasaki Heavy Industries, Ltd. | Yokohama National University | 14 |
| Yokohama National University | Sumitomo Electric Industries, Ltd. | 5 |
| Kawasaki Heavy Industries, Ltd. | Chlorine Engineers Corp. | 3 |
| De Nora Permelec Ltd. | Chlorine Engineers Corp. | 3 |
| Nippon Shokubai Co., Ltd. | Yokohama National University | 3 |
| Industrie De Nora S.p.A. | Cameron Health Inc. | 2 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Asahi Kasei and Agfa-Gevaert lead on divergent technology emphases
The top two highlighted applicants illustrate the field’s dual innovation axes: integrated electrolyser cell architecture versus diaphragm/membrane material engineering.
Asahi Kasei
Asahi Kasei holds 68 patent families — the largest position in the corpus — concentrated in electrolytic cell configuration (C25B 9), hydrogen/chlorine production processes (C25B 1), and electrode design (C25B 11). Recent-period momentum shows a 27% decline versus the prior three-year window, suggesting a maturing programme rather than active acceleration, though the absolute portfolio remains the largest.
families: 68Agfa-Gevaert
Agfa-Gevaert holds 51 patent families and is the fastest-accelerating major filer, at 3.6× its prior three-year volume. Its emphasis falls on diaphragm/membrane materials (C25B 13) and electrolytic production processes (C25B 1), a profile distinct from the cell-assembly focus of the Japanese incumbents. This momentum and material-science orientation position Agfa-Gevaert as the most dynamic challenger in the current window.
families: 51| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| Asahi Kasei Corporation | 8 | ▼ -27% |
| Kawasaki Heavy Industries, Ltd. | 3 | ▲ new entrant |
| De Nora Permelec Ltd. | 3 | ▲ new entrant |
| Agfa-Gevaert NV | 36 | ▲ 3.6× vs prior 3-yr |
| Nippon Shokubai Co., Ltd. | 9 | ▼ -40% |
| ThyssenKrupp Uhde Chlorine Engineers GmbH | 28 | ▲ new entrant |
| Tokuyama Corporation | 7 | ▼ -65% |
| Yokohama National University | 10 | ▲ new entrant |
Under-served branches adjacent to the dominant electrolysis core
Beyond the dominant C25B electrolytic-production class, several IPC branches show low patent density relative to their technical relevance to diaphragm and AEM systems, representing areas where prior-art coverage is sparse.
H01M · Batteries, cells & fuel cells
H01M carries only 48 patent records — 4% of the branch distribution — despite the direct structural and materials overlap between AEM electrolysis cells and anion-exchange membrane fuel cells. Ion-exchange membrane design, electrode-membrane assembly, and degradation mechanisms are shared engineering problems. A team with AEM electrolysis IP could extend into fuel-cell configurations with relatively low incremental R&D, and the sparse prior art reduces freedom-to-operate obstacles.
Search this in Eureka →B01D · Separation processes (filtration)
B01D holds 43 patent records — 4% share — covering membrane separation and filtration, adjacent to diaphragm permselectivity and gas-bubble management in electrolysers. Improved gas-liquid separation within the cell stack is a known performance bottleneck, and tailored microporous or asymmetric membrane architectures developed under B01D frameworks could address it. The low density suggests this functional angle has not been heavily patented by current participants.
Search this in Eureka →How leaders differ by technology route across C25B sub-classes
Route coverage across the main technology branches in the current evidence set.
| Player | C25B 1 · Electrolytic production of compounds | C25B 9 · Electrolytic production of compounds | C25B 13 · Electrolytic production of compounds | C25B 15 · Electrolytic production of compounds | C25B 11 · Electrolytic production of compounds |
|---|---|---|---|---|---|
| Asahi Kasei Corporation | Strong · 55 | Strong · 65 | Moderate · 27 | Moderate · 19 | Moderate · 27 |
| De Nora Permelec Ltd. | Strong · 40 | Strong · 48 | Moderate · 21 | Moderate · 12 | Strong · 29 |
| Kawasaki Heavy Industries, Ltd. | Strong · 35 | Strong · 49 | Strong · 32 | Emerging · 5 | Moderate · 21 |
| Agfa-Gevaert NV | Strong · 45 | Moderate · 25 | Strong · 51 | Emerging · 6 | Absent |
| Nippon Shokubai Co., Ltd. | Strong · 27 | Strong · 22 | Strong · 39 | Absent | Absent |
| Yokohama National University | Strong · 24 | Strong · 24 | Absent | Absent | Strong · 21 |
| Tokuyama Corporation | Strong · 20 | Strong · 27 | Moderate · 9 | Moderate · 13 | Absent |
Frequently asked questions
The corpus covers 608 patent families in scope. China is the leading filing jurisdiction by patent records, followed by Europe (EPO) and WIPO (PCT).
Asahi Kasei holds the largest position with 68 patent families, followed closely by Kawasaki Heavy Industries (54), De Nora Permelec (53), and Agfa-Gevaert (51). The top five filers account for 37% of the hundred largest filers’ combined total.
The field is in a Growth stage. Three-year filing volume is up 228% versus the prior three-year window. Annual filings peaked at 129 families in 2023 and have eased since, though recent years are understated by publication lag, so the multi-year expansion trend remains intact.
Agfa-Gevaert shows the strongest recent momentum among major filers, at 3.6× its prior three-year volume. ThyssenKrupp Uhde Chlorine Engineers GmbH and Yokohama National University are recorded as new entrants in the recent window. Asahi Kasei and Nippon Shokubai show declines of 27% and 40% respectively, suggesting maturing programmes.
The most active collaboration is between Kawasaki Heavy Industries and De Nora Permelec, with 42 jointly filed families. Kawasaki Heavy Industries and ThyssenKrupp Uhde Chlorine Engineers (Japan) account for 28 joint families, and De Nora Permelec and Yokohama National University share 16 joint families.
The branches H01M (batteries, cells, and fuel cells) and B01D (separation processes) each hold relatively few patent records — 48 and 43 respectively — despite clear technical relevance to AEM cell design and gas-liquid separation. C02F (water and wastewater treatment) and C08L (polymer compositions) are also lightly filed adjacent branches worth monitoring.
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Disclaimer. This page is generated from PatSnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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