First they prototyped a mini fuel cell, now it seems Sony hasn’t given up yet on their idea of a bio battery, which was introduced back in 2007. The company is still working on the battery, which can be recharged not by using methanol as fuel but glucose. Sony says the battery features a high energy density, is safe to use, and environmentally friendly.
Users can recharge the battery by using a bottle of coke, for example, when their cell phone died. The energy that can be generated by the glucose found in a single bowl of rice is the same of that in 96 AA batteries.
This sounds pretty cool but the bio batteries still look pretty big at 39x39x39mm. And depending on what you power with them, you need to carry around several of them.
Sony is currently exhibiting the bio battery at the 6th Hydrogen and Fuel Cell Expo in Tokyo.