NEC Develops Rechargeable Organic Battery

August 04, 2005 by Jeff Shepard

Researchers at NEC Corp. (Japan) have developed a new type of rechargeable battery that is based on organic compounds and could be useful in a wide range of IT-related applications, such as protection of desktop PCs during power supply interruptions. The Organic Radical Battery (ORB) is based on a similar cell structure to a lithium-ion battery, but uses an organic compound called PTMA instead of poisonous ingredients like lithium and cobalt. The prototype cells measure 55 mm x 43 mm, have a thickness of 4 mm (about the size of three stacked credit cards), and each cell weighs 20 g.

The ORB can deliver much more power than a lithium-ion battery of the same size. However, the energy density is lower than lithium-ion. The combination points towards applications where a large amount of power is needed for a short time. For example, the ORB was used to provide power to a PC to backup data and shutdown properly in the event of a main power failure. Only four of the ORB cells were required to keep the desktop PC running for the 10 or 20 seconds required to carry out such an operation. It's not the same as an uninterruptible power supply (UPS), which can typically power a PC for about an hour, but the small size and likely low cost or the ORB means it could potentially become a standard feature inside desktop PCs, unlike UPS units that are bulky and expensive.

The ORB has other advantages over current rechargeable battery technologies. It's able to maintain an almost constant voltage during discharge and also loses its ability to be fully charged at a much slower rate than competitors. The battery can also be charged very fast. With enough current supplied, the battery can be charged to about 80 percent of its capacity in just one minute, which could make it suitable for wireless applications where fast charging is advantageous. Another advantage that comes from its close structure to lithium-ion is that the manufacturing process is very similar and so mass production, when or if it occurs, could likely be done on existing battery production lines with only minor adjustments.

More work remains on fine-tuning the ORB, and NEC plans to also spend the next two to three years working on possible uses for the technology as it moves towards possible commercialization.