EDLC Reliability & Degradation Patent Landscape 2026
A small set of specialist and industrial players dominate this niche field, with OU Skeleton Tech Group and FastCap entities collectively holding the largest share of the top-ranked filers. Annual filing volume has eased back from its 2018 peak, placing the field in a decline phase, though the United States remains the primary protection jurisdiction by a wide margin.
Skeleton Tech and FastCap lead a concentrated but fragmented top tier
OU Skeleton Tech Group ranks first among the top hundred filers, followed closely by FastCap Ultracapacitors LLC and FastCap Systems Corp — entities that together represent a single technology lineage — making the FastCap cluster effectively the largest single commercial force in this space.
The top five filers account for 26% of the combined output of the hundred largest filers, a moderate concentration figure that reflects a field where no single actor holds a commanding lead. Below the top five, rankings compress quickly, with most applicants holding single-digit patent record counts.
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 1 | OU Skeleton Tech Group | 16 | |
| 2 | FastCap Ultracapacitors LLC | 15 | |
| 3 | FastCap Systems Corp | 13 | |
| 4 | Maxwell Technologies Global LLC | 11 | |
| 5 | Elna Co Ltd | 10 | |
| 6 | Kawasaki Jukogyo KK | 10 | |
| 7 | AGC Inc | 10 | |
| 8 | Panasonic Holdings Corp | 9 | |
| 9 | Honda Motor Co Ltd | 7 | |
| 10 | Semiconductor Energy Laboratory Co Ltd | 7 |
| # | Applicant | Patent records | Share |
|---|---|---|---|
| 11 | YEDA RES & DEV CO LTD | 6 | |
| 12 | Sustainable Energy Technologies Inc | 6 | |
| 13 | Battelle Memorial Institute | 5 | |
| 14 | UCAP Power Inc | 4 | |
| 15 | Atlas Power Technologies Inc | 4 | |
| 16 | Tokin Corp | 4 | |
| 17 | NEC Corp | 4 | |
| 18 | Nantong Jianghai Capacitor Co Ltd | 4 | |
| 19 | Panasonic Intellectual Property Management Co Ltd | 3 | |
| 20 | Nichicon Corp | 3 |
The presence of both dedicated ultracapacitor specialists (Skeleton, FastCap, Maxwell Technologies Global) and diversified industrial and materials firms (Elna, Kawasaki Jukogyo, AGC, Panasonic Holdings) in the top tier signals that reliability and degradation work is split between pure-play developers and component manufacturers protecting application-specific solutions.
The most recent 18–24 months of filing data are subject to publication lag and should be treated as incomplete; apparent low counts in 2024–2026 do not necessarily reflect a further structural decline. Longer-window growth, applicant concentration, and technology-route coverage are therefore more reliable signals than the latest-year bar alone.
Filing activity peaked in 2018 and has since eased; capacitor physics dominates the technology mix
The trend chart maps annual filing volume from 2017 to 2026, while the technology composition chart breaks down IPC class coverage across the corpus.
Annual filing trend
Annual filings reached a clear high in 2018 before settling into a lower, irregular cadence through the early 2020s, with a secondary uptick in 2023. Counts for 2024 onward are incomplete due to publication lag and should not be read as a continued drop.
↗ Hover for values · click a bar to ask EurekaTechnology composition
H01G (Capacitors) is the overwhelmingly dominant class, as expected for a capacitor-specific topic. Secondary classes — G01R (electric and magnetic measurement), H01M (batteries, cells and fuel cells), H02J (power supply and grid systems), and C01B (non-metallic elements and inorganic compounds) — reflect the diagnostic, hybrid-storage, system-integration, and materials dimensions of degradation research. The long tail of lower-count classes including B60L (electric vehicle propulsion), B82Y (nanotechnology applications), and G06N (AI-based computing) points to emerging application and modelling 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.
Supercapacitor to electrochemical hybrid system wi…
A method for powering an electric vehicle including an electrochemical battery and one or more supercapacitor batteries includes determining self-discharge rate data for the one or more supercapacitor batteries and, in response to the self-discharge rate data satisfying at least one threshold condition, notifying a user to charge the one or more… (excerpt from the patent abstract)
| # | Patent | Citations |
|---|---|---|
| 1 | Electric double-layer capacitor and carbon materia… | 106 |
| 2 | Thermopolymerizable composition for battery use | 81 |
| 3 | Electric double-layer capacitor and carbon materia… | 59 |
| 4 | High capacitance electric double-layer capacitor | 59 |
| 5 | Carbon material and method of making same | 58 |
| 6 | Method of supplying electric current, method of st… | 56 |
| 7 | High temperature energy storage device | 43 |
| 8 | Polarizing electrode for electric double-layer cap… | 42 |
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 competitive structure means for R&D investment decisions
Four structural dimensions — maturity, concentration, collaboration, and geography — shape the risk-return profile of entering or extending work in EDLC reliability and degradation.
Decline phase: annual volume has eased from its 2018 peak
The lifecycle stage is classified as Decline, with annual filings easing back from the 2018 peak and a recent-window growth rate of –19%. This suggests that foundational reliability concepts are becoming well-covered, and incremental filings may face prior-art density in core H01G claims. New entrants should look for residual white space in adjacent IPC branches rather than attempting broad capacitor-physics claims.
Lifecycle: DeclineModerate top-tier concentration with a rapid drop-off below rank five
The top five filers hold 26% of the combined output of the hundred largest filers, leaving the remaining 74% distributed across a large number of smaller applicants. This structure is typical of a field where application-specific know-how matters more than platform scale. A mid-tier entrant with genuine materials or system-level differentiation can realistically compete on quality rather than volume.
HHI: moderateTwo documented co-filing pairs: Elna–AGC and Kawasaki–Shizuki Electric
The most active co-filing pair is Elna Co Ltd and AGC Inc (10 joint records), reflecting a materials-supplier / capacitor-manufacturer collaboration on electrolyte and electrode interface durability. Kawasaki Jukogyo and Shizuki Electric Co Ltd have 6 joint records, pointing to a system-integration angle in industrial or rail applications. No broader consortium-level collaboration is evident, leaving open-ecosystem partnership as a potential strategic lever for new entrants.
2 active pairsUS-centric filing with meaningful secondary coverage in Japan, EPO, and China
The United States leads with 70 patent records, followed by Japan (38), Europe via EPO (31), China (30), and WIPO PCT filings (26). India (19) and Israel (10) show meaningful secondary presence, consistent with active university and government research programs in those markets. South Korea and Germany each have only 3 records, suggesting limited protection in those otherwise significant capacitor manufacturing markets.
Lead office: USGo 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 |
|---|---|---|
| Elna Co Ltd | AGC Inc | 10 |
| Kawasaki Jukogyo KK | Shizuki Electric Co Ltd | 6 |
Co-filing pairs, ranked by the number of jointly-filed patent families.
Skeleton Tech leads on volume; FastCap entities dominate on combined cluster weight
The top-ranked applicants are all specialist energy-storage companies, distinguishing this field from broader capacitor landscapes where diversified electronics manufacturers tend to dominate.
OU Skeleton Tech Group
Ranks first with 16 patent records, concentrated entirely in H01G 11 (electrochemical capacitors) and H01G 13 (capacitor manufacturing), with a secondary thread in H01M 10 (battery and cell electrochemistry). The H01M overlap signals work on hybrid or degradation-comparable storage chemistries. No momentum trend is directly reported for Skeleton in the evidence.
patent records: 16FastCap Systems Corp
Ranks third individually with 13 patent records but is part of a FastCap cluster (FastCap Ultracapacitors LLC at 15 + FastCap Systems Corp at 13 = 28 combined records) that collectively outweighs any single applicant. Technology focus sits squarely in H01G 11 and H01G 9 (conventional capacitors), with a small B23K 20 (welding and joining) thread suggesting cell assembly and hermeticity work relevant to reliability. FastCap Ultracapacitors LLC carries a new-entrant momentum flag in the recent filing window.
patent records: 13| Applicant | Recent (3 yrs) | Trend |
|---|---|---|
| FastCap Systems Corp | 5 | ▲ new entrant |
| Semiconductor Energy Laboratory Co Ltd | 2 | ▲ new entrant |
Under-served adjacent branches worth monitoring
Several IPC classes appear at low-to-moderate counts relative to the dominant H01G core, pointing to branches where the patent density is comparatively thin and technical relevance to EDLC degradation is plausible.
G01R · Electric & Magnetic Measurement
With 30 patent records, G01R is the largest adjacent branch but remains a fraction of the H01G core, indicating that in-situ and real-time degradation measurement methods — impedance spectroscopy, capacitance fade monitoring, leakage-current diagnostics — are under-patented relative to their engineering importance. A team with sensor integration or signal-processing expertise could establish a defensible position in condition-monitoring IP before this space densifies.
Search this in Eureka →H02J · Power Supply & Grid Systems
H02J carries 25 patent records in this corpus, reflecting system-level reliability concerns: balancing circuits, charge/discharge management under degraded conditions, and grid-integration resilience. The count is sparse relative to the operational importance of these functions in transport and grid-storage deployments. An entry path exists through fault-tolerant power management architectures that explicitly account for capacitor aging models, an area where G06F (5 records) and G06N (5 records) AI-modelling branches are also thin.
Search this in Eureka →How leading applicants differ by IPC technology route
Route coverage across the main technology branches in the current evidence set.
| Player | H01G 11 · Capacitors | H01G 9 · Capacitors | G01R 31 · Electric & magnetic measurement | H02J 7 · Power supply & grid systems | H01M 10 · Batteries, cells & fuel cells |
|---|---|---|---|---|---|
| FastCap Systems Corp | Strong · 24 | Emerging · 4 | Emerging · 2 | Absent | Absent |
| OU Skeleton Tech Group | Strong · 14 | Absent | Absent | Moderate · 6 | Moderate · 6 |
| AGC Inc | Strong · 10 | Strong · 10 | Absent | Absent | Absent |
| Panasonic Holdings Corp | Strong · 10 | Strong · 7 | Absent | Moderate · 3 | Absent |
| Elna Co Ltd | Strong · 10 | Strong · 10 | Absent | Absent | Absent |
| Maxwell Technologies Global LLC | Strong · 12 | Moderate · 4 | Absent | Absent | Absent |
| Kawasaki Jukogyo KK | Strong · 8 | Strong · 8 | Absent | Absent | Absent |
Frequently asked questions
The corpus contains 113 patent families in scope for EDLC reliability and degradation, filed across multiple jurisdictions globally.
OU Skeleton Tech Group leads with 16 patent records, followed by FastCap Ultracapacitors LLC (15), FastCap Systems Corp (13), Maxwell Technologies Global LLC (11), and Elna Co Ltd and Kawasaki Jukogyo each with 10. Together these five account for 26% of the combined output of the top hundred filers.
The lifecycle stage is Decline. Annual filings peaked in 2018 and have eased since, with a recent-window growth rate of –19%. Note that 2024–2026 counts are incomplete due to publication lag and do not necessarily reflect a further structural fall.
The United States leads with 70 patent records, followed by Japan (38), Europe via EPO (31), China (30), and WIPO PCT filings (26). India (19) and Israel (10) have meaningful secondary presence.
The most-cited work relates to electric double-layer capacitor carbon materials (106 and 59 citations), a thermopolymerizable composition for battery use (81 citations), high capacitance EDLC design (59 citations), and high-temperature energy storage devices (43 citations). Patent numbers were not returned in the evidence for all records.
Two co-filing pairs are documented: Elna Co Ltd and AGC Inc with 10 joint patent records (materials-supplier and capacitor-manufacturer collaboration), and Kawasaki Jukogyo and Shizuki Electric Co Ltd with 6 joint records (industrial system-integration focus). No broader multi-party consortium is evident in the evidence.
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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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