Flow Battery Patents: Who Leads, Where the Gaps Are 2026
- Ownership is spread thin. the leading assignee holds 734 records and the top 5 combined account for just 14.5% of all 12,863 records in scope — no single filer controls this field.
- Filing has plateaued, not collapsed. the complete-year comparison shows 2021 (1,022) to 2024 (990) essentially flat at -3%, after a 2023 peak of 1,180.
- Grid electronics claims sit alongside the cell chemistry. H02J (power supply & grid systems) appears in 15.0% of records, second only to H01M at 67.4%, showing how much of this landscape is systems integration rather than pure electrochemistry.
Filing growth compares 2021 (1,022 records) with 2024 (990) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 12,863 records in scope (CR5), not by the ranked leaders only.
What the flow battery patent record actually shows
Flow battery patenting spans two distinct claim territories: the electrochemical cell itself — electrolyte stability, electrode capacity, state-of-charge management — and the power electronics and grid-integration layer that turns a stack into a dispatchable asset. The search set behind this page, 12,863 records filed between 2015 and 2026, captures both. H01M (batteries, cells & fuel cells) dominates at 67.4% of records, but H02J’s 15.0% share signals that a meaningful share of filing activity is about control and grid behaviour, not the redox chemistry alone.
No single company dominates this field the way early flow battery pioneers might suggest. The leading assignee holds 734 records against a field of 12,863, and the top 10 combined reach only 19.6% of all records in scope. That pattern — a modest leader plus a long tail of single- and few-filing entrants — is typical of a technology still being worked out at the systems-integration level, where chemistry, power electronics and software control each attract separate filers.
Filing trends and technology composition
Publication lags filing by roughly 18 months, so the most recent one or two years in the trend below are understated and should not be read as a decline. The technology composition chart uses IPC subclasses, and because a single record can carry several classes, the shares sum to more than 100% of the record total.
Filing trend, 2017-2026
Filings rose from 915 in 2017 to a peak of 1,180 in 2023. The last complete-year comparison, 2021 to 2024, shows 1,022 to 990 — a -3% shift, essentially flat rather than falling. Treat 2025 and 2026 figures as provisional; they will revise upward as later publications catch up.
Technology composition by IPC subclass
H01M (batteries, cells & fuel cells) covers 67.4% of the 12,863 records in scope, with H02J (power supply & grid systems) at 15.0%. Smaller but notable shares sit in G01R electric measurement (4.5%), B60L electric vehicle propulsion (4.4%) and C25B electrolytic production (3.8%) — evidence that flow battery claims increasingly touch adjacent fields like EV charging infrastructure and electrolytic manufacturing.
Shares are the percentage of the 12,863 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Flow Batteries Patent Landscape with Eureka
This page is one run against one query. Ask Eureka your own question about flow batteries patent landscape and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Redox Flow Battery System for Distributed Energy Storage
A large stack redox flow battery system provides a solution to the energy storage challenge of many types of renewable energy systems. Independent reaction cells arranged in a cascade configuration are configured according to state of charge conditions expected in each cell. The large stack redox flow battery system can support multi-megawatt implementations suitable for use with power grid applications. Thermal integration with energy generating systems, such as fuel cell, wind and solar systems, further maximizes total energy efficiency. The redox flow battery system can also be scaled down to smaller applications, such as a gravity feed system suitable for small and remote site application.Filed by EnerVault Corporation, published 2011-05-19 — an early and frequently-referenced articulation of cascade cell architecture for grid-scale flow battery deployment.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20090216910A1 | Computing infrastructure | 1,027 |
| 2 | US9722236B2 | Apparatus and method for use in storing energy | 843 |
| 3 | US8706914B2 | Computing infrastructure | 692 |
| 4 | US20120235579A1 | Methods, apparatus and systems for providing occupancy-based variable lighting | 500 |
| 5 | US20080097655A1 | Method and system to provide a distributed local energy production system with high-voltage DC bus | 496 |
| 6 | US20100047671A1 | High energy density redox flow device | 459 |
| 7 | US20160248631A1 | Computing infrastructure | 361 |
| 8 | US20050162018A1 | Multiple bi-directional input/output power control system | 350 |
| 9 | US20110200848A1 | High energy density redox flow device | 345 |
| 10 | US20220187847A1 | Robot Fleet Management for Value Chain Networks | 341 |
Citation counts favour older records simply because they have had more time to accumulate citations within the searched corpus — treat this as a signal of influence on subsequent filing, not of current technical importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Three patterns in the data matter more than the raw counts: how thin the concentration at the top really is, where the technology composition points beyond pure electrochemistry, and how the geography of filing splits between jurisdictions.
Ownership is fragmented, not cornered
The leading assignee holds 734 records; the fifth-ranked holds 142. Combined, the top 5 account for 14.5% of all records in scope, and the top 10 reach 19.6%. That leaves roughly four-fifths of filing activity spread across a long tail — a field where freedom-to-operate analysis has to look well beyond the household names.
A plateau, not a downturn
Filings peaked in 2023 at 1,180 before easing. The reliable year-over-year comparison — 2021's 1,022 against 2024's 990 — puts the shift at -3%, which reads as a mature, steady filing rate rather than retreat. Figures for 2025 and 2026 will rise as publication catches up with filing.
Cell chemistry still anchors the field, but grid electronics is close behind
H01M carries two-thirds of records, but H02J's 15.0% share and smaller pockets in G01R, B60L and C25B show that a substantial minority of filers are claiming around control systems, measurement, EV integration and electrolytic production rather than the redox couple itself.
Filing is US-led but genuinely global
The United States leads with 4,270 records, followed by the EPO (1,989), WIPO/PCT (1,598), China (894), Australia (783) and India (661). That spread means a clearance search confined to one office will miss a meaningful share of the active claim space.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to flow batteries patent landscape, with the prior art for and against each one.
Who is filing, and where the field is still open
The assignee ranking runs across 100 companies, counted in records — it is the full ranking the dataset returns, not a curated top list. Momentum data shows several established filers pulling back in the latest tracked year, which combined with the technology composition points to specific sub-areas still open for a first strong claim.
A clear leader without a dominant position
The top-ranked assignee holds 734 records against a field of 12,863 — enough to matter for freedom-to-operate work but nowhere near enough to foreclose the field. Its share of the whole is well below what would justify treating this as a one-company technology.
Several established filers are pulling back
Recent-year momentum shows multiple assignees with sharp year-over-year declines in filing volume, including drops of -67%, -75% and -80% among named entrants, alongside filers at 0% or -100% YoY. That is consistent with a field consolidating around fewer but larger filings rather than expanding filer count.
Collaboration is concentrated in a handful of pairings
Only 10 co-assignee pairs appear in the data, and one pairing accounts for 125 co-assigned records on its own — far ahead of the next strongest pairs. Most filers in this field patent alone rather than jointly.
| Assignee | Recent year | YoY |
|---|---|---|
| Fluence Energy LLC | 5 | 0% |
| UOP LLC | 2 | -67% |
| Lockheed Martin Advanced Energy Storage LLC | 1 | -80% |
| CMBlu Energy AG | 1 | -75% |
| ESS Tech Inc | 0 | -100% |
| Sumitomo Electric Industries Ltd | 0 | -100% |
| Strong Force VCN Portfolio 2019 LLC | 0 | -100% |
| Institute of Process Engineering, Chinese Academy of Sciences | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is clearance, licensing or new filing strategy.
Run a freedom-to-operate check against the long tail
With 80% of records held outside the top 10 assignees, a clearance search limited to the largest filers will miss most of the active claim space. A full landscape pull across the ranked 100 is the safer baseline.
Explore the full assignee ranking in EurekaWatch the grid-electronics overlap
H02J's 15.0% share alongside H01M's 67.4% suggests systems-integration claims are worth tracking separately from cell chemistry claims, especially where B60L and G01R classes overlap.
Trace IPC overlaps in EurekaRevisit 2025-2026 figures once publication catches up
The most recent one to two filing years will rise as publication lag closes. Treat any near-term decline reading with that in mind before drawing conclusions about the field slowing.
Track live filing trends in EurekaCommon questions on flow battery patents
The leading assignee in this dataset holds 734 records out of 12,863 total, which is a meaningful lead but far from field-dominating. The top 5 assignees combined account for only 14.5% of all records, and the top 10 reach 19.6%. In practice this means ownership is fragmented across a long tail of companies and research institutes, so competitive analysis needs to look well past the largest filer to get a real picture of freedom to operate.
Filing rose steadily through the mid-2010s and peaked in 2023 at 1,180 records. Comparing the last two complete years, 2021 (1,022) to 2024 (990), the change is -3%, which reads as a plateau rather than a decline. Figures for 2025 and 2026 are still partial because publication typically lags filing by around 18 months, so those years will revise upward and should not be used to call a downturn.
The core class is H01M (batteries, cells & fuel cells), covering 67.4% of the 12,863 records in scope. H02J (power supply and grid systems) follows at 15.0%, reflecting how much of the field is about grid integration and control rather than cell chemistry alone. Smaller but relevant shares appear in G01R (electric measurement, 4.5%), B60L (EV propulsion, 4.4%) and C25B (electrolytic production, 3.8%), each pointing to adjacent claim territory worth checking separately.
The United States is the largest single receiving office with 4,270 records, followed by the European Patent Office (1,989) and WIPO under the PCT (1,598). China (894), Australia (783) and India (661) each carry a meaningful share as well. A search or clearance exercise limited to one jurisdiction will miss a substantial portion of the active filings, particularly given how close the US, EPO and PCT totals are to each other.
Relative to the dense core claims around cell chemistry, several adjacent areas show thinner filing density: state-of-charge estimation algorithms for multi-stack balancing, electrolyte stability additives aimed at extended cycling life, and grid dispatch control software coordinating multiple stacks. The overlap between flow battery claims and separation-membrane durability (B01D) or electrolytic feedstock production (C25B) is also comparatively thin given how central those processes are to a working system. These are not guaranteed white space — they need a direct search before filing — but the composition data flags them as less crowded than the core electrochemistry claims.
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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.