Battery test cells have generated up to 50 milliwatts, or enough electricity to power music playback on a memory-type Walkman. Sony said in a statement released in Japan on Thursday that the output is the highest for a bio battery of this type.
The battery generates electricity through the use of enzymes that break down carbohydrates, which is essentially sugar. Sony has increased battery output by efficiently immobilizing enzymes and the electronic conduction materials, while retaining enzyme activity at the anode, an electrode through which positive electric current flows into a polarized device.
Sony also developed a new structure for the cathode, which is an electrode through which positive current flows out of a polarized electrical device. The new structure efficiently supplies oxygen to the cathode while ensuring that appropriate water content is maintained to optimize enzyme activity and the flow of electricity.
The bio battery could evolve into an ecologically friendly device, because sugar is a naturally occurring energy source produced by plants through photosynthesis and can be found in most areas of the earth, Sony said. In addition, Sony made the battery casing of vegetable-based plastic.
Such ecologically friendly batteries could help reduce the disposal problem with batteries used today. Many of the chemicals used in current batteries are toxic and environmentally destructive. Sony plans to continue its research into so-called "immobilization systems," electrode composition, and other technologies to increase power output and durability. Sony hopes to one day use the new technologies for practical applications.
Sony presented its research this week as an academic paper at the American Chemical Society National Meeting & Exposition in Boston.
In other recent ecologically friendly battery research, scientists at the Rensselaer Polytechnic Institute reported last week creating a paper-sized device that functions as a high-energy battery and a supercapacitor that can use human blood and sweat to recharge. The device is lightweight, thin, flexible, and geared toward future use for medical implants, transportation, and gadgets.