Rensselaer Polytechnic Institute researchers have developed a new energy storage device that resembles a sheet of black paper. The nanoengineered battery is lightweight, ultra-thin, flexible, and geared toward meeting the design and energy requirements of tomorrowÃs gadgets, implantable medical equipment, and transportation vehicles. It is completely integrated and can be printed like paper. The device can be rolled, twisted, folded, or cut into any shape. The paper batteries can also be stacked, like a ream of printer paper, to boost total power output.
The device is unique in that it can function as both a high-energy battery and a high-power supercapacitor. Another key feature is the capability to use human blood or sweat to help power the battery. More than 90 percent of the device is made up of cellulose, the same plant cells used in newsprint, lunch bags, and nearly every other type of paper. The researchers infused the paper with aligned carbon nanotubes, which give the device its black color. The nanotubes act as electrodes and allow the storage devices to conduct electricity. The device provides the steady power output comparable to a conventional battery, with a supercapacitor's quick burst of high energy.
Along with use in small handheld electronics, the paper batteries' light weight could make them ideal for use in automobiles, aircraft, and boats. The paper also could be molded into different shapes, such as a car door, which would enable important new engineering innovations. The hybrid battery/supercapacitors have potential as power supplies for devices implanted in the body. The team demonstrated that naturally occurring electrolytes in human sweat, blood, and urine can be used to activate the battery device.