Few component categories carry as many names as this one. The same 2.7 V, 3000 F cell can appear as an ultracapacitor in one catalog, a supercapacitor in another, and an electric double-layer capacitor on the standard it was tested against. Buyers comparing quotes sometimes suspect they are pricing three different products.
They are not. This page settles the terminology: which names are interchangeable, which ones describe a different storage mechanism, and what to write on a purchase order so a supplier ships the part you actually need.
Are Ultracapacitor and Supercapacitor the Same Device?#
Yes. The two words describe the same class of component: a capacitor that stores charge in an electric double layer at the electrode–electrolyte interface, with capacitance measured in farads rather than microfarads.
The split is regional and commercial, not technical. US manufacturers built their catalogs around “ultracapacitor”. European and Asian suppliers, together with the standards bodies, use “supercapacitor” or “electric double-layer capacitor”. A part labelled with either word has the same construction, the same voltage window and the same aging behaviour.
The two words stop being interchangeable one level down. “Supercapacitor” is the umbrella term, and not every supercapacitor is an EDLC.
Where the Two Names Come From#
| Where you see it | Wording | Example |
|---|---|---|
| Maxwell Technologies | ultracapacitor | application notes titled “…Characterizations of Ultracapacitors” |
| Eaton / PowerStor | supercapacitor | Technical Note 10888, “Supercapacitor Modules Application Guidelines” |
| IEC 62391-1 | electric double-layer capacitor | standard title |
| Academic literature | supercapacitor, EDLC | used interchangeably |
Maxwell’s application notes use “ultracapacitor” throughout (maxwell.com), while reference coverage of the underlying physics sits under “supercapacitor” (Wikipedia).
The practical consequence: you cannot infer the storage mechanism from the label. A catalog page that says “supercapacitor” may be describing a hybrid lithium-ion capacitor with a different voltage window and a different charge profile. The datasheet, not the noun, tells you what you are buying.
The Term Tree: EDLC, Hybrid and Lithium-Ion Capacitors#
| Type | Storage mechanism | Typical cell voltage | Is it an EDLC? |
|---|---|---|---|
| EDLC | physical charge separation at the electrode–electrolyte interface, no chemical reaction | 2.5–2.7 V | Yes |
| Pseudocapacitor | fast, reversible faradaic reactions (RuO₂, MnO₂) | varies by chemistry | No |
| Hybrid / lithium-ion capacitor | one double-layer electrode plus one lithium-ion intercalation electrode | 3.8 V | No |
A lithium-ion capacitor is a supercapacitor but not an EDLC. Our 3.8 V lithium-ion capacitor range is a hybrid: one electrode stores charge in a double layer, the other by lithium-ion intercalation. That is why it reaches 3.8 V per cell where an EDLC stops near 2.7 V, and why the two are not drop-in substitutes even at the same capacitance.
Stored energy scales with the square of the voltage:
$$E = \frac{1}{2}CV^{2}$$For the same capacitance, a 3.8 V hybrid cell therefore holds roughly twice the energy of a 2.7 V EDLC (\(3.8^{2}/2.7^{2}\approx 1.98\)). The gain comes from the electrochemistry, not from the name on the label.
What Buyers Call It in Other Languages#
English is not the only place the terminology splits. When you source across regions, the local word is often not a translation of either English term.
| Language | Common term | Note |
|---|---|---|
| Russian | ионистор (ionistor), суперконденсатор | ionistor is a long-established term and remains the default search word |
| Spanish | supercondensador | “ultracapacitor” appears as a loanword in technical literature |
| German | Doppelschichtkondensator, Superkondensator | Doppelschicht = double layer |
| Japanese | 電気二重層コンデンサ | older Japanese datasheets sometimes use ゴールドキャパシタ (gold capacitor) |
If you are matching a part number against a Russian-language datasheet, searching ионистор will find it faster than searching supercapacitor.
What to Write in a BOM or Purchase Order#
- Lead with the family and the parameters. A line item such as
EDLC, 2.7 V, 3000 F, ESR ≤ 0.25 mΩleaves no room for interpretation; the noun only tells the supplier which family you mean. - Match the supplier’s own wording. Maxwell lists parts under ultracapacitors, Eaton under supercapacitors. Searching the supplier’s term returns the right datasheet faster than arguing about synonyms.
- Avoid informal shorthand on formal documents. “Supercap” is conversational and “gold capacitor” is a historical Japanese trade name; a new supplier may quote a different package on the strength of the word.
- Disambiguate hybrids explicitly. If a line item could be met by either an EDLC or a lithium-ion capacitor, state the voltage window. A 2.7 V and a 3.8 V part are not interchangeable, however similar the capacitance.
Which Cells Fit Which Term#
Every listing in our catalog uses the manufacturer’s own wording, and each datasheet confirms the storage mechanism.
- EDLC single cells: Maxwell 2.7V 3000F, CAP-XX EDLC 2.7V 5F
- Multi-cell modules: Maxwell 16V 500F, Maxwell 48V 165F
- Hybrid cells, not EDLC: Eaton LIC 3.8V 200F, Jianghai LIC 3.8V 200F
- Full range: all supercapacitors
If a listing is ambiguous, the technical FAQ explains how our QC process verifies capacitance, ESR and leakage current before dispatch. For the measurement procedure itself, see how to measure supercapacitor capacity; for the comparison against batteries, see supercapacitors vs batteries.
Is an Ultracapacitor the Same as a Supercapacitor?#
Yes — same device, same construction, same voltage window. The words differ by supplier origin and region, not by technology.
Is an EDLC the Same as a Supercapacitor?#
No. An EDLC is one type of supercapacitor. The family also includes pseudocapacitors and hybrid lithium-ion capacitors, which store charge by different mechanisms.
Is a Lithium-Ion Capacitor an EDLC?#
No. A lithium-ion capacitor pairs one double-layer electrode with one lithium-ion intercalation electrode, which is why it runs at 3.8 V instead of 2.7 V. Our lithium-ion capacitor guide covers the trade-offs.
Do You Stock Both Ultracapacitors and Supercapacitors?#
Yes — it is the same inventory under two labels. The catalog carries EDLC cells and modules from Maxwell, SAMWHA, CRRC and CAP-XX, plus hybrid lithium-ion capacitors from Eaton and Jianghai.
What Should I Ask For When Requesting a Datasheet?#
Give the family name, the capacitance and the voltage, and we will send the original manufacturer datasheet. If you are comparing an EDLC against a hybrid part, ask for ESR and the voltage window as well — two cells with the same capacitance can differ by a factor of two in stored energy.
Summary#
Ultracapacitor and supercapacitor are the same component under two names. EDLC describes how the most common type stores charge, and only that second distinction changes what you buy. State the family and the parameters first; the word on the label stops mattering. Browse the full supercapacitor range or send us your specification.