Vanadium Redox Flow Battery Patents: Leaders & Trends 2026
- Filing peaked in 2021 at 79 families, then declined through the midpoint year — this is a maturing claim space, not a growing one.
- H01M dominates with 647 of 650 records, while adjacent IPC subclasses like C07D, H02J and B60L carry fewer than 30 records each, marking thin but present cross-domain activity.
- The strongest co-assignee pair files 18 shared records, well ahead of the next pairs at 4 — collaboration in this field is rare and concentrated.
What the vanadium redox flow battery patent record shows
Vanadium redox flow battery patenting sits almost entirely inside H01M — batteries, cells and fuel cells — with 647 of 650 published families touching that subclass. The search corpus spans electrolyte concentration, membrane crossover, stack design, energy-power decoupling and shunt current: the mechanical and electrochemical problems that separate a working flow battery from a lab demonstration. Filing rose through the late 2010s, peaked in 2021, and has since fallen back toward the level seen at the start of the window, a pattern consistent with a chemistry that has moved from open invention into narrower, defensive claiming around specific stack and membrane configurations.
Receiving-office data shows the United States and the EPO carrying the bulk of filings, with WIPO PCT applications and Australian, Indian and Canadian filings forming a second tier — evidence of deliberate multi-jurisdiction protection rather than single-market filing. Publication lags actual filing by roughly 18 months, so the drop-off visible in the most recent one or two years understates real filing activity; it should not be read as a sudden stop.
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Filing trend and technology composition
Two views of the same 650-family dataset: how filing volume has moved year over year, and how those families distribute across IPC subclasses beyond the core battery classification.
Filing trend, 2017–2026
Annual filings ran from 59 in 2017 to a peak of 79 in 2021, easing to 44 by the midpoint year of 2022 and continuing to decline into the partial final year. Read the tail years as understated, not as a genuine collapse in activity.
IPC subclass distribution
H01M accounts for 647 of 650 records, confirming this is a tightly scoped battery-hardware search. Smaller counts in C07D, H02J, C07C, B60L, G01R, C01B and C07G point to electrolyte chemistry, grid integration, EV propulsion and measurement work that touches flow battery patents without being centred on them.
Shares are the percentage of the 650 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Vanadium Redox Flow Batteries with Eureka
This page is one run against one query. Ask Eureka your own question about vanadium redox flow batteries and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art and a representative recent filing
SYSTEM UND VERFAHREN ZUM AUSGLEICHEN EINER VANADIUM-REDOX-FLOW-BATTERIE (EP4053951A1)
A method for chemical reduction of an oxidised vanadium redox flow battery during operation by adding an organic reductant, where the same redox-active vanadium solution occupies both the cathode and anode tanks. The method monitors state of charge during charge and discharge configurations and applies the reductant to rebalance the electrolyte, addressing capacity loss from side reactions without requiring a separate rebalancing cell.Filed by Aarhus Universitet, 2022-09-07 — an example of university-originated electrolyte-rebalancing IP rather than a commercial stack patent.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20110223450A1 | Cascade Redox Flow Battery Systems | 227 |
| 2 | US20100003545A1 | Redox Flow Battery System for Distributed Energy Storage | 205 |
| 3 | US20100323264A1 | Fuel system using redox flow battery | 202 |
| 4 | US6764789B1 | Redox flow battery | 142 |
| 5 | US20160268621A1 | Fuel system using redox flow battery | 112 |
| 6 | US20150129081A1 | Fuel System Using Redox Flow Battery | 110 |
| 7 | US20160013507A1 | Fuel system using redox flow battery | 107 |
| 8 | US5851694A | Redox flow type battery | 107 |
| 9 | US9293781B2 | Fuel system using redox flow battery | 104 |
| 10 | WO2010118060A1 | Fuel system using redox flow battery | 100 |
Citation counts favour older, foundational filings inside a searched corpus — treat them as a measure of influence on later claim drafting, not as a signal that these are the most commercially active patents today.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the filing pattern implies for R&D and IP strategy
The numbers point to a chemistry where the foundational stack and electrolyte claims are already staked out, and where remaining opportunity sits in narrower configurations and adjacent integration.
Volume has already crested
Filings peaked in 2021 at 79 and eased through the 2022 midpoint of 44 before declining further. Combined with the 18-month publication lag, this reads as a chemistry settling into narrower claiming rather than one in early growth.
Almost all activity sits in one subclass
With 647 of 650 families in H01M, the dataset confirms this is squarely a battery-hardware search. The handful of records reaching into C07D, C07C and C01B chemistry subclasses suggest electrolyte additive work is a smaller, more specialised slice.
Protection is deliberately multi-jurisdiction
The United States and Europe carry the largest shares, with a substantial PCT tier and secondary filing in Australia, India and Canada. That spread signals applicants treating flow battery IP as globally defensible, not confined to a home market.
Co-assignment is rare and lopsided
Only 10 co-assignee pairs exist across the corpus, and the strongest pair files far more jointly than any other combination. Most applicants in this space patent alone.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to vanadium redox flow batteries, with the prior art for and against each one.
Who is filing, and where the gate sits for new entrants
Recent-year momentum has cooled across the named assignees tracked in this corpus, with only one showing any filing in the latest partial year — consistent with the broader decline visible in the filing trend.
UOP (Universal Oil Products) is the only assignee still filing
Among the tracked assignees, Universal Oil Products shows one filing in the latest year while every other named assignee — including ESS Tech, Sumitomo Electric, Invinity Energy Systems, Kemiwatt and Lockheed Martin Advanced Energy Storage — shows none in that window.
Sumitomo Electric and Kansai Electric Power file jointly at scale
The Sumitomo Electric–Kansai Electric Power pair files together far more than any other combination in the dataset, pointing to a long-running utility-and-manufacturer partnership around grid-scale deployment.
Cascade and distributed-storage system patents anchor the field
The most-cited records in the corpus describe cascade redox flow battery systems and distributed-energy-storage architectures, filed years before the 2021 peak — later applicants are building claims that sit downstream of this foundational IP.
| Assignee | Recent year | YoY |
|---|---|---|
| Universal Oil Products (UOP) | 1 | — |
| ESS Tech, Inc. | 0 | — |
| Sumitomo Electric Industries, Ltd. | 0 | — |
| Invinity Energy Systems | 0 | — |
| Kemiwatt | 0 | — |
| Lockheed Martin Advanced Energy Storage, LLC | 0 | — |
| UNIENERGY TECHNOLOGIES LLC | 0 | — |
| Biaoneng Co., Ltd. | 0 | — |
Where to take this analysis
The filing decline and thin cross-subclass activity both raise questions that a static table cannot answer on its own.
Check freedom-to-operate before scaling a stack design
With citation leaders concentrated in cascade and distributed-storage architectures, a new stack configuration should be checked against those foundational claims before committing to tooling.
Run a freedom-to-operate checkTrack the assignees still active in the latest year
Only one named assignee shows filing activity in the most recent partial year — worth monitoring for signs of renewed investment or a pivot to a different chemistry.
Set up assignee monitoringProbe the under-claimed adjacent subclasses
C07D, H02J and B60L each carry fewer than 30 records — enough to indicate interest, not enough to indicate saturation. A targeted search inside these subclasses may surface open claim space.
Explore adjacent IPC subclassesCommon questions about vanadium redox flow battery patents
This dataset tracks 650 patent families published between 2015 and mid-2026 that combine vanadium redox flow battery or flow-battery-stack terminology with specific technical terms like electrolyte concentration, membrane crossover, stack design, energy-power decoupling or shunt current, filtered to IPC classes H01M8, H01M4 and H01M50. Filing activity rose through the late 2010s, peaked in 2021 at 79 families, and has declined since. The true count for the most recent one to two years will rise as publications catch up, since publication typically lags filing by around 18 months.
Named assignees in this corpus include Sumitomo Electric Industries, Kansai Electric Power, Invinity Energy Systems, ESS Tech, Kemiwatt, Lockheed Martin Advanced Energy Storage and Universal Oil Products, among others. Sumitomo Electric and Kansai Electric Power form the strongest co-filing relationship in the dataset at 18 shared records, well ahead of any other pair. Recent-year filing has slowed across nearly all of these assignees, with Universal Oil Products the only one showing activity in the latest partial year.
The search terms behind this dataset — electrolyte concentration, membrane crossover, stack design, energy-power decoupling and shunt current — map to the core engineering problems in flow battery deployment: keeping the vanadium electrolyte stable and balanced, stopping ions crossing the membrane and degrading efficiency, packaging cells into a stack that scales, and managing the parasitic currents that leak through shared electrolyte manifolds. Almost all of the 650 records sit in IPC subclass H01M, confirming these are battery-hardware claims rather than pure chemistry patents. Smaller pockets of activity in grid-integration (H02J) and EV-propulsion (B60L) subclasses show where flow battery IP starts to overlap with adjacent systems.
No — filings peaked in 2021 at 79 and had fallen to 44 by the 2022 midpoint, with further decline into the most recent years tracked. This does not necessarily mean the technology is losing commercial interest; it is consistent with a field moving from broad foundational claiming into narrower, more defensive patenting around specific configurations. The most recent one or two years in any such trend are always undercounted because of publication lag, so the true 2025–2026 filing rate is higher than currently visible.
The thinnest but present activity sits in subclasses adjacent to the core H01M battery claims: organic-reductant electrolyte rebalancing, shunt-current mitigation across multi-stack systems, grid-integration controls overlapping H02J, EV-adjacent flow battery propulsion overlapping B60L, and membrane-crossover diagnostics. Each of these has enough records to show applicant interest but far fewer than the core stack and electrolyte claims, suggesting room for a well-drafted first claim rather than a crowded field. Any freedom-to-operate check in these areas should still be run against the highest-cited foundational patents, since broad early claims can reach into narrower later work.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.