EU project designs self-rechargeable solar batteries
If, like most people these days, your mobile phone is your lifeline, then you know how frustrating it feels when the phone's battery runs out of juice and has to be recharged. To solve the problem, researchers in EURO-PSB, an EU funded project, have designed a polymer battery with integrated thin-solar cells, which can re-charge itself when exposed to natural light. The results of the now completed project are published in the journal Solar Energy. Weighing in at just two grams and measuring less than one millimetre thick, the prototype battery is flexible enough to be used in a wide range of low-wattage electronic gadgets, including flat but bendable objects like a smart card and, potentially, mobile phones with curves. The device is designed to ensure that the battery is always charged with the optimum voltage, independently of the light intensity. Each solar strip in a cell can produce 0.6 volts and the battery can fit the requirements of the device by simply adding extra strips to a cell. In order to sustain the life of the cells, which are vulnerable to photodegradation after only a few hours of air exposure, the researchers encapsulated them inside a flexible gas barrier. This extended their life for about 3,000 hours. Researchers say that the production of the solar cells is cost effective, since they can be printed on a roll-to-roll machine at low temperatures. Tests on the prototype are proving that using solar-powered batteries are feasible alternatives to existing batteries. They were found to be effective under low-light conditions, such as sunlight shining in through a window. Researchers however believe that artificial light, such as office light, may be too weak to generate enough power for mobile phones. The project consortium says that a solar-battery device could be on sale as early as next year. In addition to the solar technology, VARTA-Microbattery, a German battery company and one of the project consortium partners, has also developed an extremely thin and highly flexible lithium-polymer battery which is already on the market, in Apple's new iPod nano. The battery is as thin as 0.1 millimetre, can be recharged more than 1,000 times, and has a relatively high energy density.
Countries
Austria, Switzerland, Germany, Estonia, France