Low resistance, thin, and lightweight electric double-layer capacitors (EDLC/supercapacitors)

Positioning as capacitors

Electric double-layer capacitors (EDLC/supercapacitors) can provide large amounts of energy due to their large capacitance.
TDK's electric double-layer capacitors (EDLC/supercapacitors) are available with capacitances ranging from several mF to 500 mF.
Rated voltage ranges from 3.2 V to 4.2 V.
Adequate energy can be obtained without raising the voltage.
Since they are low resistance, power density is outstanding.

Product Map　(Capacitance - Rated Voltage)

TDK has an extensive lineup of various capacitor types, which can support a wide range of capacitance and voltage values. Details can be viewed by clicking on the product types.

Category		Features
Electric Double-Layer Capacitors (EDLC / Supercapacitors)		EDLCs are capacitors with intermediate stored energy between that of a capacitor and a battery (secondary battery). By causing ions to adhere to the surface of activated carbon electrodes which have been soaked in electrolyte solution, an Electric Double Layer is formed to accumulate electric charge, giving these power storage devices extraordinarily large capacitance and energy density.

Electric double-layer capacitors (EDLC/supercapacitors) have extremely high capacitance compared to other capacitors and have high energy characteristics.
Also, although the energy density (the amount of power stored per unit of volume) is inferior to that of a battery (LIB), it is a device with high power density (output power per unit of volume) and excellent instantaneous power.

TDK’s electric double-layer capacitors (EDLC/supercapacitors) were designed to have extremely high power density and high energy density compared to other electric double-layer capacitors and are suitable for high-energy applications.

Principles of electric double-layer capacitors (EDLC/supercapacitors)

Electric double-layer capacitors (EDLC/supercapacitors) store electric charge by absorbing ions on the surface of activated carbon electrodes immersed in an electrolytic solution to form an electric double layer. Since the capacitance is proportional to the area of the electric double layer formed at the interface of the activated carbon, the electrode is made using activated carbon with a large surface area. Electric double-layer capacitors (EDLC/supercapacitors) do not involve a chemical reaction of the electrode active material, they can be charged and discharged rapidly, and because of the physical phenomenon of ion absorption and desorption, there is little deterioration and charging/discharging cycles are excellent. TDK’s electric double-layer capacitors (EDLC/supercapacitors) optimize the paired electrode, separator, and electrolyte to reduce resistance. By connecting two units in series in a single package, the rated voltage is increased.

Types of electric double-layer capacitors (EDLC/supercapacitors)

Electric double-layer capacitors (EDLC/supercapacitors) are categorized as followings according to structure and configuration.
The product lineup includes various types including compact chip-type and coin-type components to large cylindrical and square modules with multiple connections.

Structure and shape	Product external shape
Chip type
Coin type, mold type
Pouch type, laminated type
Cylindrical, square
Module (types with large number of cylinders or squares are connected)

Electrostatic capacitance
Ultra-low capacity: 0.1F or less
Low capacity: approx. 0.1F – 1F
Medium capacity: approx. 1F – 100F
High capacity: 100F or more

Main Applications
Clocks and memory backups for various electronic devices
Standby electric power for consumer electronics and AV products
Battery load leveling for mobile devices, current assistance for high-brightness LED flashes or wireless transmission, instantaneous power disruption backup for SSDs, energy harvesting
Road marking studs, LED signs, driving small motors in toys
Energy recovery in industrial equipment and automobiles, uninterruptible power supplies (UPS), emergency power supply for wind power generation control

Lineup and structure of TDK’s electric double-layer capacitors (EDLC/supercapacitors)

Electric double-layer capacitors (EDLC/supercapacitors) are a type of capacitor that have extremely high capacitance compared to other capacitors.
TDK's electric double-layer capacitors (EDLC/supercapacitors) have low resistance and high power density (output power per unit of volume) at the industry’s best levels, making them devices with excellent instantaneous power. Pouch-type components maintain the charging/discharging cycle life and safety of EDLCs, achieving thin and lightweight specifications.

Product Image	Features	Height	L×W size	Capacitance	Rated Voltage	Impedance	Operating Temperature Range	Series, Types	Product Catalog	Part No. Lists
	Thin Type	0.4mm	27 x 17mm	5 to 15mF	3.2V(Continous) 5.0V(Peak)	7Ω (1kHz)	-20 ~ +60°C	EDLC041720 (Preliminary)	119KB
	Low Profile Type	2.1mm	20 x 25mm (Without Lead)	350mF	4.2V(Continous) 5.5V(Peak)	55mΩ (1kHz)	-40 ~ +70°C	EDLC212520	112KB
		2.6mm		500mF		35mΩ (1kHz)	-40 ~ +70°C	EDLC262520	110KB
		2.7mm		500mF	4.2V(Continous) 5.5V(Peak)	95mΩ (1kHz)	-20 ~ +85°C	EDLC302520 (Preliminary)	119KB
	Small Footprint Type	3.7mm	20 x 14mm (Without Lead)	500mF	4.2V(Continous) 5.5V(Peak)	40mΩ (1kHz)	-40 ~ +70°C	EDLC371420	110KB
		3.8mm		500mF	3.2V(Continous) 4.2V(Peak)	70mΩ (1kHz)	-30 ~ +85°C	EDLC381420	110KB

TDK’s electric double-layer capacitors (EDLC/supercapacitors) are available in two types--wound type and film type. The wound type features two cells in which an electrode and a separator are wound at the same time and enclosed using an aluminum laminate film. In addition, the thin laminated type has electrodes and separators laminated and enclosed using a stainless steel lamination film to maintain high bending strength and support bending and twisting tests.

Characteristics of TDK’s electric double-layer capacitors (EDLC/supercapacitors)

Electric double-layer capacitors (EDLC/supercapacitors) perform charging and discharging by absorbing and releasing ions on the surface of activated carbon electrodes.
Since there is no chemical reaction of the electrode surface, they can be charged and discharged rapidly, and because of the physical phenomenon of ion absorption and desorption, electrode deterioration is minimal and charge/discharge cycle characteristics are excellent.

The graph above shows changes in electrical characteristics when TDK electric double-layer capacitors (EDLC/supercapacitors) are subjected to repeated charging/discharging cycled by charging at 5.5 V, discharging at 20 A in 5 ms and charging to 0.9 A 20,000 times.

As shown in Figure 6, there is almost no change in characteristics as a result of the charging/discharging cycles.
As a result, products can be used with confidence despite charging/discharging at high current.

Measurement conditions

EDLC262520-501-2F-40
Capacitance: 500 mF
Impedance @ 1 kHz: 35mΩ typ.

The main materials making up electric double-layer capacitors (EDLC/supercapacitors) are activated carbon, aluminum, and ion electrolyte.
The capacitors are repeatedly charged and discharged by a mechanism that does not involve chemical reactions to achieve the functions of a capacitor.
Since the material composition and mechanism are safe and clean, there is no danger of ignition or smoke, even if the component is penetrated by a nail, bent, or heated when fully charged.

Uses of TDK’s Electric Double-Layer Capacitors (EDLC/supercapacitors)

Areas of use that take advantage of the characteristics of TDK’s electric double-layer capacitors (EDLC/supercapacitors).

By assisting the limits of battery power, it is possible to achieve functions that are not possible with a battery alone.
As a backup during power loss, a large amount of energy can be achieved per unit.
By storing micro-energy or regenerative energy, effective use of energy is possible.

Battery assist: Power assist when rewriting a screen using battery drive/electronic paper

With electronic paper, using EDLCs for battery assist smooths screen display speed, and the pages can be turned like flipping actual paper. They are also effective for enlarged display of small figures or tables, enabling smooth display of PDF files.

Battery assist: Voltage leveling during high loads using battery drive/portable audio players

In audio equipment, where sudden power changes occur, a large amount of power is simultaneously supplied from the electric double-layer capacitor (EDLC/supercapacitors) to the amplifier unit to assist the battery.

D class amps are used in portable audio players and other devices.D class amps consist of a low-pass filter circuit block made up of a PWM modulator, two output power MOSFET, noise suppression filer (including LPF inductor) , and notch filter with ESD protection function.
By combining the output power MOSFET (in the example below, the PVCC part) with a TDK electric double-layer capacitor (EDLC/supercapacitors), even if a sudden power change occurs, the electric double layer capacitor (EDLC/supercapacitors) can be used instantaneously, assisting the battery by supplying a large amount of power to the amplifier unit.

Battery assist: Power assist during wireless transmission using battery drive/water and gas smart meters

As the high-performance of water and gas smart meters increases, wireless information transfer functions are being added. Water and gas smart meters, use batteries as a power source, but with the improvement of wireless functions, power assistance is becoming necessary. Pouch type electric double-layer capacitors (EDLC/supercapacitors), which are effective for battery assist and are compact, are attracting attention.

Power supply assist: Power supply assist during operation of fingerprint sensors/fingerprint authentication cards

Fingerprint authentication cards use power supply assist during operation of fingerprint sensors. There are many types of NFC terminals, and there are differences in the power that can be supplied. Electric double-layer capacitors (EDLC/supercapacitors) are effective for smooth card authentication operation even with terminals that are currently in widespread use. Since biometric data does not leak outside the card, the high level of security is attracting attention and thin electric double-layer capacitors (EDLC/supercapacitors) that make them possible are useful. In addition, the card is a safe device structure, and they can be disposed of with reassurance.

Power backup: Power backup during power loss (Last Gasp)/SSD

Large-capacity electric double-layer capacitors (EDLC/supercapacitors) are suitable for use a backup power supplies in the event of unexpected power failure and can be used for power loss protection for devices such as SSDs.

For enterprise SSDs and so on, NAND flash memory is used as the storage element, and when writing data, the data is temporarily stored in DRAM cache memory and is collectively written to the flash memory to improve the data writing speed.
If an unexpected power failure occurs, to ensure that the data in the cache memory is reliably written to the NAND flash memory, generally multiple capacitors are used and power loss protection measures are implemented.
Large-capacity electric double-layer capacitors (EDLC/supercapacitors) can be used for such power loss protection measures.

Micro-energy storage: Storage of micro-energy generated from the environment and provision when needed/Batteryless wireless sensors

TDK’s electric double-layer capacitors (EDLC/supercapacitors) have low impedance, so excellent charging can be achieved even with unstable amounts of power from energy harvesting and discharging suitable for the application is possible, making them ideal for energy harvesting applications.

Regenerative energy storage: Storage of regenerative energy and battery assist/micromotors

Utilization of surplus regenerative power from regenerative energy is a technology that will contribute to further energy conservation in the future.
As small robots become more common, electric double-layer capacitors (EDLC/supercapacitors) will be used to efficiently store surplus power in batteries.
Stable operation is possible by passing unstable energy through electric double-layer capacitors (EDLC/supercapacitors).
The stored energy can also be used to provide a large amount of energy to assist during operation.