Japanese scientists at Waseda University have recently developed a polymer based flexible paper-like battery that can be recharged. This organic radical battery could be used in pocket-sized integrated circuit cards, used for memory storage and micro processing within the next three years. The power-rate performance is strikingly high. It only takes one minute to fully charge the battery and it has a long cycle life, often exceeding 1000 cycles.
The designed battery consists of a redox-active organic polymer film around 200 nanometres thick. Nitroxide radical groups are attached, which act as charge carriers. The Japanese scientists made the thin polymer film by a solution-processable method: a soluble polymer, polynorborene with pendant nitroxide radical groups. The team made the thin polymer film by a solution-processable method - a soluble polymer with the radical groups attached is ‘spin-coated' onto a surface. After UV irradiation, the polymer becomes cross linked with the help of a bisazide crosslinking agent. The photo cross linking method used by the Japanese team overcomes the problem and makes the polymer mechanically tough. The battery has a high charge/discharge capacity because of its high radical density (two radicals for each repeat unit). In the future, these batteries may be used in applications that require high-power capability rather than high-energy density, such as a battery in electronic devices and motor drive assistance in electric vehicles.
A drawback of some organic radical polymers is their solubility in the electrolyte solution which results in self-discharging of the battery; however, the polymer needs to be soluble so it can be spin-coated. The photocrosslinking method used overcomes this problem and makes the polymer mechanically tough.

Earlier, Japan 's NEC Corporation had developed an ultra-thin, flexible, rechargeable battery capable of super-fast (30 second) charging, which can be embedded into smartcards and intelligent paper. The organic radical battery (ORB) uses a type of plastic called organic radical polymer as its cathode.
Organic radical polymer assumes an electrolyte-permeated gel state that makes the rechargeable battery remarkably flexible and pliant. In addition, the organic radical polymer electrode reaction is extremely fast and the supporting salts migrate through gel state polymer very smoothly. This results in little resistance to the charging reaction and an incredibly fast charging time of less than 30 seconds. Not only is this new battery thin, flexible and rechargeable, but it is also environmentally friendly as unlike conventional rechargeable batteries, it does not contain any harmful heavy metals such as mercury, lead or cadmium.
Key features of the battery include:

	An exceedingly thin structure (300 microns), which will enable it to be embedded into objects such as smartcards and intelligent paper in the future.
	A pliant and bendable structure, as flexible plastic is used as the cathode material
	An ultra-fast charging speed of less than 30 seconds.
	A high energy density of approximately 1 mWh (mili Watt hour) per cm squared. This means, for example, that if the ORB was used in an active RFID device, it would support up to approximately several tens of thousands of signal transmissions on a single charge.
	Environmentally friendly, as it does not contain any harmful metals.