Electric Double-Layer Capacitor for Smart Cards
TDK Corporation announces the release of an ultra-thin, high-energy capacitor suitable for powering devices such as electronic paper displays in the next generation of smart cards. The EDLC041720-050-2F-13, a 5mF electric double-layer capacitor. With a footprint of 27 mm x 17 mm and a maximum thickness of just 0.45 mm, the new capacitor can be mounted inside a smart card or other thin device.
When fully charged, it provides around 50mJ of energy to power a load. In smart cards, the fast-charging characteristics of the EDLC041720-050-2F-13 make it compatible with radio-frequency energy harvesting circuits. Tests based on NFC energy-harvesting circuits in use today show that its 5mF capacitance can be charged in less than 1s by the field emitted by a standard NFC reader.
When embedded in a contactless ticketing card for users of a metro transit system, for instance, the EDLC041720-050-2F-13 is fully charged in the time it takes the user to present the card to the entry gate’s card reader. The energy stored on the card on entry to the transit system is sufficient to refresh the card’s e-paper display, enabling the card to show for instance an updated read-out of the user’s remaining credit.
The device’s 5mF capacitance also provides sufficient energy to power advanced biometric forms of authentication, as used for example in contactless access control cards. While RF energy harvesting is suitable for many smart and contactless payment card applications, the capacitor may in addition be charged by other forms of harvested energy, such as that generated by TDK film solar cells.
Despite being only about one fifth as thick as TDK’s previous generation of EDLCs, the new EDLC041720-050-2F-13 is highly resistant to damage by twisting and bending, and offers a long operating lifetime. It can reliably be used in smart cards that must conform to ISO 10373-1 5.8 for dynamic bending stress, and ISO 10373-1 5.9 for dynamic torsion stress. It is rated for operation over a temperature range of -20 to 60 degrees C. It also has high resistance to electro-static discharges and pressure. The EDLC041720-050-2F-13 contains no rare or heavy metals, is non-flammable, and poses no risk of explosion. It is available now for sampling.
