Phase-Change Thermal Storage Patents: Who Leads, Where Gaps Are 2026
- Filing peaked in 2021 at 15 families, then slowed through the 2022 midpoint — activity is cooling from its high, not accelerating into it.
- China leads filing location with 18 records, ahead of the United States at 13 and India at 12, making this a genuinely multi-jurisdiction claim space rather than a single-market race.
- C09K materials claims dominate at 42 of 63 records, while heat-exchange apparatus (F28D) trails far behind at 10 — most of the fight is over the material itself, not the hardware around it.
What this landscape covers
Phase-change materials (PCMs) store and release heat as they cross a melting point, but repeated cycling exposes weaknesses — supercooling, phase separation, corrosion of containment, and degrading heat-transfer performance over hundreds of cycles. This landscape isolates the patent activity specifically addressing thermal cycling stability, degradation resistance, and supercooling control, rather than PCM chemistry in general. The corpus spans 63 patent families published between 2015 and mid-2026, concentrated overwhelmingly in materials-science claims under C09K.
Because publication lags filing by roughly 18 months, the 2025–2026 filing counts in the trend chart are undercounts of actual activity — the real trajectory beyond the 2021 peak will not be visible in the data for another year or so.
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Filing trend and technology composition
Two views of the same 63 families: how filing activity has moved year over year, and which technical subclasses are absorbing the claims.
Filing trend, 2017–2026
Filings ran from zero in 2017 to a peak of 15 in 2021, sitting at 5 by the 2022 midpoint — a pattern of rapid early growth followed by a slowdown rather than a straight climb.
IPC subclass composition
C09K (materials for miscellaneous applications) accounts for 42 of the 63 records, roughly two-thirds of the corpus. F28D (heat-exchange apparatus), A01N, C08K, B01J, C04B, C08L and C12N split the remainder in single digits each, showing the claim pressure is heavily weighted toward material formulation over device design.
Shares are the percentage of the 63 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Phase-Change Thermal Storage Reliability and Durability with Eureka
This page is one run against one query. Ask Eureka your own question about phase-change thermal storage reliability and durability and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited prior art in this space
Stable salt hydrate-based thermal energy storage materials (US20210340423A1)
A phase change material composition for latent heat storage built around a salt hydrate with a melting temperature between 1°C and 100°C, stabilized by a polysaccharide matrix — nanocellulose, sulfonated polysaccharide, starch, glycogen or chitin — with a composite article claimed alongside the composition.Filed by UT-BATTELLE, LLC, published 2021-11-04. Cited 13 times within this corpus.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20160090520A1 | Heat storage material composition, heat storage device, and heat storage method | 17 |
| 2 | US20210340423A1 | Stable salt hydrate-based thermal energy storage materials | 13 |
| 3 | EP3000859A1 | Heat storage material composition, heat storage device, and heat storage method | 9 |
| 4 | WO2021146122A1 | Devices and methods for high-stability supercooling of aqueous media and biological matter | 8 |
| 5 | JP1990036235A | Polyolefin composite containing phase transition substance | 8 |
| 6 | US20220325937A1 | Devices and Methods for High-Stability Supercooling of Aqueous Media and Biological Matter | 5 |
| 7 | CN110669476A | 一种有机复合相变储能材料及其制备方法和应用 | 5 |
| 8 | CN116426248A | 一种光热转化增强型CaCO<sub>3</sub>壳层相变微胶囊及其制备方法 | 4 |
| 9 | US11560503B2 | Stable salt hydrate-based thermal energy storage materials | 4 |
| 10 | EP4043416A1 | Thermal energy storage media based on concrete and use of hybrid cement as a binder for production of such co… | 4 |
Citation counts reflect influence within the searched corpus and favour older filings; treat them as a signal of what shaped the field, not of what is currently strongest.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three patterns stand out once the counts are read against the technical problem, not just the assignee league table.
Growth is slowing, not stopping
The peak year of 15 families in 2021 was followed by a drop to 5 at the 2022 midpoint. Combined with the 18-month publication lag, this reads as a market that filed hard around a specific stability breakthrough window and has since settled into steadier, lower-volume filing.
Material formulation is the contested ground
Two-thirds of records sit in C09K, the materials-for-misc-applications subclass, versus only 10 in F28D heat-exchange apparatus. Anyone entering this space is more likely to collide with existing claims on the PCM formulation itself than on the device that houses it.
No single jurisdiction dominates
China leads with 18 records, but the United States (13) and India (12) are close behind, with EPO, WIPO and Austria adding smaller counts. A freedom-to-operate check in only one office would miss a majority of the relevant art.
Older heat-storage composition patents still anchor the field
The most-cited record, US20160090520A1 on heat storage material composition and device, predates most of the corpus and still draws the highest citation count. Newer entrants are building on, not replacing, this earlier composition-and-device framing.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to phase-change thermal storage reliability and durability, with the prior art for and against each one.
Who is filing, and where the field is still open
The assignee base mixes Chinese universities, a US national laboratory, and a small number of corporate filers, with most parties filing only once or twice in this specific reliability-and-durability niche.
Recent activity has thinned out sharply
Among the tracked assignees, only one — a China-based energy technology firm — shows a filing in the latest year; the rest, including the University of California Regents and Panasonic, show none in the same window. This is consistent with the broader slowdown from the 2021 peak.
Co-filing is rare and mostly academic
Only six co-assignee pairs appear across the corpus. The strongest pairing links the University of California Regents with the Arizona Board of Regents (representing the University of Arizona); another links South China University of Technology with its own Zhuhai innovation research institute.
A genuinely international filer base
Filers span Chinese universities (South China University of Technology, Changsha University of Science & Technology, Xi'an Polytechnic University), a US national laboratory (UT-Battelle), and Japanese and Spanish institutions, with corresponding filings distributed across China, the US, India, EPO, WIPO and Austria.
| Assignee | Recent year | YoY |
|---|---|---|
| Junheng Energy Technology (Sanming) Co., Ltd. | 1 | — |
| The Regents of the University of California | 0 | — |
| Panasonic Corporation (Japan) | 0 | — |
| South China University of Technology | 0 | — |
| UT-Battelle, LLC | 0 | — |
| Arizona Board of Regents on behalf of the University of Arizona | 0 | — |
| INDIAN INST OF TECH BANARAS HINDU UNIV VARANASI | 0 | -100% |
| Spanish National Research Council (CSIC) | 0 | — |
Where to take this analysis
The filing and citation data point to specific next steps depending on whether the goal is freedom-to-operate, whitespace filing, or tracking a competitor.
Check freedom-to-operate across three offices, not one
With China, the US and India each holding double-digit filing counts, a single-jurisdiction clearance search will miss most of the relevant art in this niche.
Run a multi-jurisdiction search in EurekaProbe the device-side claim space
F28D heat-exchange apparatus claims sit far below C09K material claims in volume — a starting point for design-around work that shifts novelty toward the hardware rather than the PCM formulation.
Explore F28D claim gaps in EurekaTrack the slowdown against 2023–2024 re-publications
The apparent drop after 2021 may partly be a publication-lag artefact; re-running this search in a few months will sharpen the real trajectory.
Set a monitoring alert in EurekaCommon questions on phase-change thermal storage patents
The bulk of this activity sits in C09K, the IPC subclass for materials used in miscellaneous applications, which accounts for 42 of the 63 records in this corpus. F28D (heat-exchange apparatus), A01N, C08K, B01J, C04B, C08L and C12N make up smaller shares, generally covering containment, additive chemistry and biological or ceramic composite angles. A search limited to F28D alone would miss the majority of the relevant filings, since most of the technical contest is over the PCM formulation itself rather than the device housing it.
Supercooling — where a PCM fails to solidify at its expected freezing point — undermines the reliability that latent heat storage depends on, and several highly cited records address it directly, including WO2021146122A1 on high-stability supercooling of aqueous media. Because supercooling control is a specific, testable failure mode, it shows up as a distinct claim angle within the broader durability search rather than being folded into general composition claims. Filers targeting this niche should expect prior art concentrated around nucleating agents and stabilizing matrices.
The assignee base is a mix of Chinese universities such as South China University of Technology, Changsha University of Science and Technology and Xi'an Polytechnic University, a US national laboratory (UT-Battelle), and corporate filers including Panasonic. Most parties in this specific reliability-and-durability niche filed only once or twice, and recent-year momentum has thinned sharply, with only one tracked assignee — a China-based energy technology firm — showing a filing in the latest year. This is a fragmented field rather than one led by a dominant repeat filer.
China leads with 18 records by receiving office, followed by the United States at 13 and India at 12, with the EPO, WIPO/PCT route and Austria adding smaller counts. This spread means a clearance or landscape search confined to one office will miss a majority of the art — a multi-jurisdiction check across at least China, the US and India is necessary for a reasonably complete picture. PCT filings are a minority route here, at only 4 records.
Filing activity rose from zero in 2017 to a peak of 15 families in 2021, then dropped to 5 by the 2022 midpoint, suggesting the strongest growth phase has passed for now. Because publication lags actual filing by roughly 18 months, the most recent one to two years in the trend will always understate true activity, so this apparent slowdown should be treated as provisional rather than final. A re-check of the 2023–2025 counts in a future data pull would confirm whether filing has genuinely plateaued or is simply still working through the publication pipeline.
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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.