What Is a Supercapacitor?
The term “supercapacitor” has become synonymous with electric double-layer carbon (EDLC) capacitors and similar high-energy storage devices and is loosely described as any capacitor that operates in the extremely high capacitance range, which is usually above 1 farad. We also include hybrid capacitors that operate in the hundreds of thousands of microfarads. Other industry names for similar high-energy storage devices include “ultracapacitor” and “pseudocapacitor.”
The supercapacitor represents an attractive value proposition for the design engineer because it can store a significantly higher energy level than conventional capacitors (on a similar size and weight basis) and can deliver that charge in either a rapid rate of time or in a slower, controlled rate of time. Thus, these devices are capacitors that can be used as short-term batteries or for shaving peak power requirements in an electrical or electronic system.
So Where Do Supercapacitors Make Their Home?
The high capacitance of a supercapacitor under a controlled release can either be used to (1) replace more expensive batteries (lithium-ion) for memory protection in low voltage applications, (2) be used in addition to a battery to provide a significant load leveling pulse discharge in high voltage applications or (3) be used alone as a pulsed power source in both low and higher voltage circuits.
In early stages of market adoption in Japan, the majority of the existing market was for coin cell and cylindrical components in the consumer audio and video imaging markets for battery backup of CMOS clock functions in video cassette recorders. In 2024, the market has expanded to include additional battery backup and burst power applications in a variety of consumer and professional electronic systems as well as for actuated power in renewable energy platforms, energy recoup in electric rail systems and for pulsed data transmission of mixed metal oxide dielectrics.
Summary Table 1.0
Supercapacitors: Mapping Out the Complex Ecosystem in 2024
Historical Development of Supercapacitor Technology
The First Carbon Capacitors: 1972
The first supercapacitors were defined as such because of their ability to generate capacitance values measured in farads (instead of microfarads and picofarads, which are the quantity of measurement by which all other capacitor products are sold). The first explorers in this market emerge in patent searches in 1972 and include technology breakthroughs in Japan, Holland, and the U.S. simultaneously.
Expanding The Carbon Capacitor Market: 1973-1998
Between 1973 and 1990, many companies in Japan and Russia began experimenting and producing a variety of small can and large supercapacitor cells whose similarities were that they had a high-power density (charge/discharge rate) expressed as watts per kilogram and a high level of energy density (for burst power). Also, the “super” capacitors had capacitance values expressed well into the farad range and had low voltage per cell, usually between 2.5 and 2.7 Vdc. By 1998, there was full-scale production of supercapacitors in Japan and the U.S. at multiple manufacturing locations.
The Participants in EDLC Capacitors Multiply: 1999-2024
Between 1999 and 2024, the number of manufacturers of supercapacitors blossomed to more than 40 companies globally. This was the direct result of the ease of market entry made even smoother by the concerted effort of key raw material vendors supplying “turn-key” anode and cathode systems to the industry.
During this time period, major manufacturers of aluminum electrolytic capacitors and power film capacitors in Japan also entered the market for carbon supercapacitors and quickly assumed market leadership positions because of their access to the existing customer base in power conversion.
Supercapacitors And Their Unique Value Proposition
So why does a small market attract so many manufacturers in electronics? The reasons can be found in the value proposition that the electric double layer and mixed metal oxide supercapacitor manufacturer offers the design engineer.
High Capacitance Density
Supercapacitors do, in fact, provide the largest capacitance value of any capacitor. And while other dielectrics measure their capacitance in picofarads (ceramics, DC film) and microfarads (tantalum, aluminum), supercapacitors measure their capacitance in millions of microfarads, or in farads. In short, they hold a tremendous amount of charge, which can be released rapidly like a capacitor (pulse discharge) or slowly, like a battery.
Lowest Cost Per Farad
If a customer needs a single capacitor with a discharge of 1 farad or higher and approaches an aluminum electrolytic capacitor manufacturer, the job would be custom and more expensive than a double-layer carbon supercapacitor. Thus, supercapacitors operating at capacitance values greater than 1 farad must largely create their own market. To date, supercapacitors have largely been successful in load leveling the power systems of electric busses and in providing burst power for actuated movement (i.e. nacelles for windmills; motor cranking- start/stop, etc.).
Wide Operating Temperature
Although capacitance change with temperature may differ between manufacturers and between supercapacitor technologies, generally speaking, supercapacitors operate superbly in very cold and very warm environments, whereas lead-acid batteries do not. This makes supercapacitors more desirable than lead-acid batteries for engine-cranking applications in harsh automotive, military, and industrial environments.
Reliable, Long-Life Operation
Supercapacitors are extremely reliable. Ten year+ operation points to continuous long-life reliability that has been field tested. This is an excellent selling point when supercapacitors are used to replace the total or partial functions of a battery. Batteries have short shelf lives and must be replaced frequently. Supercapacitors do not readily degrade and therefore do not need to be replaced. This significantly limits expenditures on maintenance, which tends to be quite costly depending on the environment in which the battery is located. Therefore, a good marketing strategy for supercapacitor vendors has been to concentrate on battery markets, where maintenance costs are high.
Safe Operation
Supercapacitors operate more safely than batteries with fewer instances of catastrophic failures. This is because many of the materials consumed in the construction of supercapacitors are designed not only to offer high energy density at operational voltages but to be inert to the environment as well, thus there is an emphasis on developing activated carbon from organic sources and water-based (KOH) electrolytes.
Applications In Load Leveling and Burst Power
Supercapacitor manufacturers were able to identify early on in ecosystem development that in a power system, supercapacitors worked best when they were paired with batteries. The battery provides for steady state power and supercapacitors provide the peak power shaving and overall system load leveling requirements that create a superior power system. It was also revealed over time that supercapacitors, as stand-alone components, also outperformed other products for burst power applications.
Using these two pillars of growth, the supercapacitor industry was able to find traction in consumer electronics circuits requiring protection of CMOS clock functions in case of a power outage, protecting solid state disc drives in server farms in case of power disruption and in load leveling power requirements in transit busses. It also gained traction for transport start/stop (engine cranking) burst data transmission from satellites, smart metering devices, and adjusting the nacelles in wind turbines.
Supercapacitors: Available Technologies
We have identified three separate markets based upon the fundamental supercapacitor technology of providing capacitance in the farad range: activated carbon, lithium-ion, and mixed metal (hybrid) supercapacitors.
Activated Carbon Supercapacitors
The majority of supercapacitors deployed today are manufactured from some form of activated carbon material, either a pressed synthetic PTFE or an activated carbon fiber fabric. Generally speaking, powder-type carbon materials that are molded and extruded into anodes represent the approach taken by many of the manufacturers of smaller components that are mass-produced because the process lends itself to mass production. Large can supercapacitors use carbon fabric wound on a mandrel and placed in a large can with separator materials and electrolytes. The large can segment of the supercapacitor market has intrigued many major scientists at key materials and packaging companies with brands that extend beyond components.
Lithium-Ion Supercapacitors
The lithium-ion supercapacitor market was born out of the need for higher voltage per cell in activated carbon-type supercapacitors. The solution is to dope the substrate with various amounts of lithium material.
Mixed Metal Supercapacitor Hybrids
The market for mixed metal oxide (MMO) supercapacitors has blossomed in the past few years for applications in aerospace, primarily for satellite transmissions and deep space communications. The massive pulse capabilities of the supercapacitor create a burst power charge that is significant. We have identified that MMO-type capacitors also have a promising future for pulsed data transmission from handheld devices.
Successful EDLC Configurations
We note that the majority of growth over the time period beginning in 1993 and into 2024 has been in (1) large can supercapacitor configurations. This also includes the double-layer carbon module assemblies. These large can EDLC capacitor product markets have experienced excellent growth over 30 years, with a significant amount of that growth consolidated within the past seven years.
EDLC Coin Cells and Cylindrical Markets
Where we have seen value growth over time has been in the older portion of the market – the double layer carbon coin cells and radial leaded capacitor configurations for printed circuit board mounting in consumer electronics and this is why Panasonic is exiting the EDLC coin cell business. Newer Li-Ion capacitors are also targeting these end markets with capacitors that demonstrate higher energy density and higher voltage per cell.
SMD EDLC Chip Packages
The double-layer carbon supercapacitor surface mount “slim-line” designs are just now gaining momentum and have a different business model, so the verdict is still out on how well the SMD chip supercapacitor will fare as a viable load-leveling solution for portable electronics
Li-Ion Capacitors
The lithium-ion supercapacitor market developed out of the double-layer carbon supercapacitor market. The lithium capacitor operates at the farad level but has higher energy density and a higher voltage per cell than the carbon capacitor market from which it was developed, making complete systems smaller because of the requirement of fewer cells to achieve the required operating voltage of a given system.
Hybrid Supercapacitor Configurations
The hybrid supercapacitor market, or what we call the mixed metal oxide supercapacitor market is of great interest to us because we see a growth market in the value-added and application-specific segment of the components market because it offers the design engineer a burst power capacitor that has extremely low equivalent series resistance (ESR).
Summary And Conclusions
Many important eyes in the global high-tech economy have looked at EDLC and mixed metal oxide supercapacitors and their potential as load-leveling devices for hybrid and electric vehicles, recouping energy, and burst power. The leading vendor portfolios also contain supercapacitor products that can be used for pulsed data transmission in satellites and for deep space communications which also fit well with the forecasted view of the global high-tech economy.
The supercapacitor is available in many types and configurations as noted in this article, but with the common thread of being at the maximum level of available capacitance value per cell. Voltages per cell are limited but are improved with newer technologies or by putting individual capacitors in assemblies. Applications are noted across multiple end markets in consumer, professional, telecommunications, and renewable energy systems. The outlook for this ecosystem remains positive because of the energy storage and burst power capabilities of supercapacitors.
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