Engineers at NEC have developed a flexible battery that is less than 1mm thick and can be charged in half a minute, the company said on Wednesday.
The battery has been designed for use in applications such as active RFID (radio frequency identification) cards and could provide enough power to keep such cards running for several weeks before requiring a recharge, said Yoshimi Kubo, chief manager of fuel cell and battery research at NEC's fundamental and environmental research laboratories, speaking at a Tokyo briefing.
The device is an 'organic radical battery', a technology developed by NEC that uses materials that are more environmentally friendly than the chemicals found in common rechargeable batteries, the company said. NEC began researching the technology in 2000 and its work has been partly funded by Japan's New Energy and Industrial Technology Development Organization (NEDO).
One of the features of such batteries is their ability to be charged quickly; the device unveiled on Wednesday can be charged to about 80 percent of its capacity in around 30 seconds.
A prototype is being demonstrated this week at an NEC event in Tokyo. The battery on show measures about 4cm square and has been fitted into a card about the same size as an identification or credit card. After a charge it can keep an LED embedded in the card lit for about 20 minutes before requiring a recharge.
Such thin batteries are important for active-type RFID cards. Most current RFID cards or tags are passive devices which aren't capable of transmitting data on their own and work when brought into proximity with a radio field from a tag reader. This typically means they work over a range of several centimetres. Active tags are more like miniature radios and can transmit over longer distances, which means they can be read without having to bring them so close to the tag reader.
NEC said it has no current plans for commercial production of the device or an estimate of how much it will cost at such a time as production begins.
It's not the first organic radical battery application developed by NEC.
A larger version of the battery was shown earlier this year and proposed as a possible future emergency power source for computers. Because the battery is capable of delivering a large amount of power in a short period NEC demonstrated it being used to power a PC for about 15 seconds, which is enough time for the PC to back up important data and shut down properly.
That application used four batteries, each of which measure 55x43x4mm, which is about the same size as a stack of three credit cards. Each cell weighs 20g. As with the prototype on show this week, NEC didn't have any immediate commercialisation plans for the technology.