Sony developed a Bio-Battery that generates electricity from carbohydrates (sugar) utilizing enzymes as its catalyst, through the application of power generation principles found in living organisms. It is an Enzymatic Biofuel Cell Battery. Test cells of this bio battery have achieved power output of 50 mW, currently the world’s highest level for passive-type Bio-Batteries. The output of these test cells is sufficient to power music play back on a memory-type Walkman.

In order to realize the world’s highest power output, Sony developed a system of breaking down sugar to generate electricity that involves efficiently immobilizing enzymes and the mediator (electronic conduction materials) while retaining the activity of the enzymes at the anode. Sony also developed a new cathode structure which efficiently supplies oxygen to the electrode while ensuring that the appropriate water content is maintained. Optimizing the electrolyte for these two technologies has enabled these power output levels to be reached.

Biobattery-BioFuel Cell Battery Generates Electricity from Sugar and GlucoseSugar is a naturally occurring energy source produced by plants through photosynthesis. It is therefore regenerative, and can be found in most areas of the earth, underlining the potential for sugar-based bio batteries as an ecologically-friendly energy device of the future. Glucose is broken down on the anode side of the battery, producing protons (H+) and electrons (e-). The protons (H+) are transferred to the cathode side through the separator, while the electrons (e-) are transported to the cathode side through the mediator, which transfers them to the external circuit. The cathode uses the enzymes to drive an oxygen-reduction reaction which ultimately produces water using both the protons (H+) and the electrons (e-) transferred from the anode. These reactions at the anode and cathode generate electric energy by creating proton (H+) and electron (e-) flow in the cell system.

Like a conventional fuel cell battery, Bio Battery basically consists of an anode, cathode, electrolyte and separator. However, Bio Battery has certain specific characteristics. First, biological enzymes are used as catalysts for the anode and cathode. Second, enzymes and electronic mediators (which transfer electrons between enzymes, and between enzymes and electrodes) are fixed on the anode and cathode.

While many technological challenges still remain, Bio Battery has great potential as a next-generation energy device. Advantages include its excellent harmony with the environment as a product fueled by a carbohydrate (glucose) having high energy density. Sony’s longer-term goal for R&D in this area is to further enhance performance to ultimately develop batteries suitable for notebook computers and other mobile devices.