Redox Flow Battery Patent Landscape 2026
Redox Flow Battery Patent Landscape in 2026
The redox flow battery IP field spans 4,219 patent families and is led by Sumitomo Electric Industries, which holds a clear margin over the next tier. The field has reached maturity — annual volume has plateaued near its peak and the competitive structure is dominated by a handful of industrial and government-backed filers.
Sumitomo Electric leads a moderately concentrated field
Sumitomo Electric Industries holds the top position with 421 patent families, nearly 43% more than second-ranked Lockheed Martin Advanced Energy Storage with 294 patent families. The top five filers — Sumitomo Electric, Lockheed Martin Advanced Energy Storage, LG Energy Solution, Dalian Institute of Chemical Physics, and CEA — together account for 27% of the hundred largest filers’ combined total.
Below the top two there is a visible tier gap before a dense mid-tier cluster that includes LG Energy Solution (183 patent families), Dalian Institute of Chemical Physics (133), and CEA (119). This two-tier structure suggests that the market leaders have built substantial prior-art moats while the mid-tier remains actively contested.
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 1 | Sumitomo Electric Industries, Ltd. | 421 | |
| 2 | Lockheed Martin Advanced Energy Storage LLC | 294 | |
| 3 | LG Energy Solution, Ltd. | 183 | |
| 4 | Dalian Institute of Chemical Physics, Chinese Academy of Sciences | 133 | |
| 5 | Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) | 119 | |
| 6 | LG Chem, Ltd. | 104 | |
| 7 | The Kansai Electric Power Co., Inc. | 97 | |
| 8 | Asahi Kasei Battery Separator Corporation | 96 | |
| 9 | Resonac Holdings Corporation | 94 | |
| 10 | ESS Tech, Inc. | 86 |
| # | Applicant | Patent families | Share |
|---|---|---|---|
| 11 | Nisshinbo Holdings Inc. | 79 | |
| 12 | California Institute of Technology | 73 | |
| 13 | Lotte Chemical Corporation | 69 | |
| 14 | 3M Innovative Properties Company | 65 | |
| 15 | Regents of the University of California | 65 | |
| 16 | Asahi Kasei Corporation | 64 | |
| 17 | Kyocera Corporation | 62 | |
| 18 | Massachusetts Institute of Technology | 57 | |
| 19 | Dalian Rongke Power Co., Ltd. | 57 | |
| 20 | PRESIDENT & FELLOWS OF HARVARD COLLEGE | 55 |
Sumitomo Electric’s position, reinforced by a long-running co-development relationship with Kansai Electric Power, reflects decades of system-level integration work. Lockheed Martin’s large portfolio signals serious defense and grid-scale ambitions, while the presence of major Korean chemical companies and French public-sector labs illustrates the breadth of institutional investment across geographies.
Patent publication typically lags filing by 18–24 months, so figures for 2024–2026 understate actual activity; trend reads for those years 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.
A plateaued filing pace dominated by core electrochemical classes
Annual filing volumes and the technology class breakdown together reveal a maturing field where incremental cell and membrane innovation remains central but adjacent application areas are beginning to attract attention.
Annual filing trend
Annual filings have fluctuated in the 440–576 range across the evidence window, with a local peak in 2019. The field is still positive on a multi-year basis, though annual volume has eased from that 2019 peak. Data for 2024–2026 are subject to publication lag and should be read as lower bounds rather than real declines.
↗ Hover for values · click a bar to ask EurekaTechnology composition
H01M (batteries, cells and fuel cells) dominates the technology mix by a wide margin, confirming that core cell chemistry and stack engineering remain the primary innovation battleground. The next-largest classes — H02J (power supply and grid systems), H01G (capacitors), C25B (electrolytic production), and C01B (inorganic compounds) — each carry a share below 5%, pointing to pockets of adjacent activity in grid integration, hybrid storage architectures, and electrolyte chemistry.
↗ 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.
Membrane for redox flow battery, method for produc…
An object of the present invention is to provide a membrane for a redox flow battery which is prevented from being curled and exhibits high power efficiency, a membrane electrode assembly for a redox flow battery, a cell for a redox flow battery, and a redox flow battery. The object can be attained by a membrane for a redox flow battery, comprising a first… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Apparatus and method for use in storing energy | 842 |
| 2 | High energy density redox flow device | 457 |
| 3 | High energy density redox flow device | 343 |
| 4 | High energy density redox flow device | 236 |
| 5 | Redox flow battery system and cell stack | 235 |
| 6 | Cascade Redox Flow Battery Systems | 227 |
| 7 | High energy density vanadium electrolyte solutions… | 219 |
| 8 | Electrochemical Energy Storage Systems and Methods | 218 |
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 IP structure means for R&D investment decisions
Reading maturity, concentration, collaboration networks, and geographic reach together helps an R&D team calibrate where differentiation is still achievable and where freedom-to-operate will be most constrained.
Field has plateaued near peak
The lifecycle stage is Maturity: annual filings have plateaued near their peak (2019), and the overall growth rate for the recent window is –7%. This means the core IP foundations — vanadium electrolytes, membrane chemistry, stack design — are well covered. Differentiation will increasingly come from system integration, novel chemistries, and adjacent applications rather than fundamental cell patents.
Lifecycle: MaturityTwo-tier structure with a clear leader gap
The top five filers account for 27% of the hundred largest filers’ combined total, with Sumitomo Electric substantially ahead of Lockheed Martin Advanced Energy Storage and a cluster of mid-tier challengers. A new entrant must either target white-space niches or accept operating in the shadow of these deep prior-art positions. The mid-tier gap between rank 2 and rank 3 leaves some room for challengers to build meaningful positions in sub-domains.
High concentrationSumitomo–Kansai Electric anchors the ecosystem
The most active co-filing pair is Sumitomo Electric Industries and Kansai Electric Power with 90 joint patent families, reflecting a long-standing utility-manufacturer partnership on vanadium flow battery systems. CEA and Orano form the dominant European co-filing pair (41 families), signaling a government-backed push in France. LG Energy Solution and the Regents of the University of California co-filed 12 families, illustrating a corporate-academic channel for novel chemistry. Dalian Institute of Chemical Physics and Dalian Rongke Power represent the main Chinese industry-academia pipeline (11 families).
Strong bilateral tiesUS leads; China and Europe are close competitors
The United States is the lead filing jurisdiction, followed by China and Europe (EPO). Japan and South Korea are also significant, reflecting the strong presence of Japanese industrial firms and Korean chemical companies in the ranking. Australia and India appear as notable secondary markets, consistent with grid-scale storage deployment programs in both countries. A new entrant should prioritize at minimum US, China, and EPO coverage for meaningful protection.
Multi-polar geographyGo 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 |
|---|---|---|
| Sumitomo Electric Industries, Ltd. | The Kansai Electric Power Co., Inc. | 90 |
| Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) | Orano SA | 41 |
| Sumitomo Electric Industries, Ltd. | Toyobo Co., Ltd. | 21 |
| Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) | Safty Group Co., Ltd. | 16 |
| Sumitomo Electric Industries, Ltd. | Toyobo MC Corporation | 13 |
| LG Energy Solution, Ltd. | Regents of the University of California | 12 |
| Sumitomo Electric Industries, Ltd. | Gelion Technologies Pty Ltd | 11 |
| Dalian Institute of Chemical Physics, Chinese Academy of Sciences | Dalian Rongke Power Co., Ltd. | 11 |
| Sumitomo Electric Industries, Ltd. | Nippon Chemical Industrial Co., Ltd. | 6 |
| Dalian Institute of Chemical Physics, Chinese Academy of Sciences | Shaanxi Huayin Technology Co., Ltd. | 6 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Sumitomo Electric and Lockheed Martin dominate; ESS Tech and LG Energy Solution are the fastest-moving challengers
The top two filers hold commanding positions built over decades, but momentum data reveal meaningful divergence: while legacy leaders are trimming output, two challengers are actively building their positions.
Sumitomo Electric Industries
Sumitomo Electric Industries holds 421 patent families — the largest portfolio in the field — concentrated overwhelmingly in H01M cell and stack technology. Its co-development program with Kansai Electric Power (90 joint families) has produced system-level IP that extends across grid-scale vanadium flow battery deployment. However, recent-period filings are down 70% versus the prior window, indicating a shift from volume filing to portfolio consolidation or a maturing of its core technology base.
patent families: 421ESS Tech
ESS Tech holds 86 patent families and is one of the fastest-growing filers in the field, with recent-period filings up 85% versus the prior window. Its technology focus is split between H01M cell chemistry and stack design, consistent with its iron flow battery platform. This momentum, combined with a commercially active product pipeline, makes ESS Tech the challenger most likely to close the gap with the established leaders in a focused chemistry segment.
patent families: 86| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| Sumitomo Electric Industries, Ltd. | 28 | ▼ -70% |
| Lockheed Martin Advanced Energy Storage LLC | 7 | ▼ -75% |
| LG Chem, Ltd. | 1 | ▼ -97% |
| Asahi Kasei Corporation | 45 | ▼ -39% |
| Dalian Institute of Chemical Physics, Chinese Academy of Sciences | 24 | ▼ -14% |
| LG Energy Solution, Ltd. | 104 | ▲ 5.5× vs prior 3-yr |
| Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA) | 29 | ▼ -68% |
| ESS Tech, Inc. | 48 | ▲ +85% |
Under-served branches adjacent to the core flow battery domain
Five IPC classes sit at the edge of the dominant H01M core with relatively low patent-record counts. Two stand out as having plausible technical value and realistic entry paths for R&D teams seeking differentiation.
H02J · Power supply and grid systems
H02J covers grid integration, power conditioning, and storage dispatch control — functions that are essential for commercial flow battery deployment but represent only a small share of records in the corpus. As flow batteries move from standalone products to grid assets managed by energy management systems, IP on dispatch algorithms, grid-forming inverters, and hybrid-system architectures becomes strategically valuable. Entry is realistic for teams with power-electronics or software competency, and the relatively low density means freedom-to-operate is less constrained than in the core H01M space.
Search this in Eureka →C25B · Electrolytic production of compounds
C25B covers electrolytic synthesis processes, which intersects flow battery technology in two ways: electrolyte preparation and regeneration, and the emerging concept of flow batteries coupled with electrochemical synthesis (e.g., hydrogen production or chemical co-generation). The branch has a modest record count relative to the total corpus, suggesting that the intersection of flow battery electrolyte management with industrial electrochemistry is not yet heavily patented. Teams working on electrolyte recycling, capacity restoration, or dual-use flow architectures would find relatively open ground here.
Search this in Eureka →How leaders differ by technology route
Strength of each leader across the main technology routes.
| Player | H01M 4 · Batteries, cells & fuel cells | H01M 8 · Batteries, cells & fuel cells | H01M 10 · Batteries, cells & fuel cells | H01M 50 · Batteries, cells & fuel cells | H01M 2 · Batteries, cells & fuel cells |
|---|---|---|---|---|---|
| Sumitomo Electric Industries, Ltd. | Strong · 300 | Strong · 389 | Moderate · 115 | Emerging · 21 | Emerging · 30 |
| Lockheed Martin Advanced Energy Storage LLC | Strong · 191 | Strong · 227 | Moderate · 100 | Absent | Emerging · 27 |
| LG Chem, Ltd. | Strong · 140 | Strong · 75 | Moderate · 67 | Absent | Emerging · 13 |
| Dalian Institute of Chemical Physics, Chinese Academy of Sciences | Strong · 118 | Strong · 100 | Absent | Absent | Absent |
| LG Energy Solution, Ltd. | Strong · 93 | Absent | Strong · 112 | Absent | Absent |
| Asahi Kasei Corporation | Absent | Absent | Strong · 95 | Strong · 86 | Moderate · 24 |
| The Kansai Electric Power Co., Inc. | Absent | Strong · 93 | Strong · 85 | Absent | Moderate · 20 |
Frequently asked questions
The corpus covers 4,219 patent families, representing global filings across all major jurisdictions. The United States is the lead filing jurisdiction, followed by China and Europe (EPO).
Sumitomo Electric Industries holds the largest portfolio with 421 patent families, well ahead of second-ranked Lockheed Martin Advanced Energy Storage with 294 patent families.
The field is at a Maturity stage. Annual filings have plateaued near their 2019 peak, and the recent-window growth rate is -7%. The apparent drop in 2024–2026 data is at least partly attributable to publication lag and should not be read as a definitive decline.
ESS Tech shows the strongest upward momentum among active challengers, with recent-period filings up 85% versus its prior window. LG Energy Solution is also accelerating, at 5.5 times its prior three-year rate, though that growth comes from a smaller prior base.
The most active co-filing pair is Sumitomo Electric Industries and Kansai Electric Power with 90 joint patent families. CEA and Orano form the leading European pair with 41 families, and Dalian Institute of Chemical Physics co-filed 11 families each with Dalian Rongke Power and with Shaanxi Huayin Technology.
Based on relative record counts, H02J (power supply and grid systems), C25B (electrolytic production), C01B (inorganic compounds), and C08J (polymer processing) are among the lower-density adjacent branches. H02J and C25B stand out for having clear technical relevance to commercial flow battery deployment while remaining relatively sparse compared to the dominant H01M class.
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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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