(650b) High-Energy Density Metal-Free Biobatteries Powered By Soft Drinks

More and more portable electronics urgently require better batteries featuring high-energy density, good safety, and low environmental impacts. Enzymatic fuel cells are a promising micro-power source for small electronics. However, incomplete oxidation of sugars mediated by few redox enzymes and low faraday efficiency result in low energy storage densities. Here we demonstrate the complete oxidization of sucrose, glucose, and fructose at the anodic compartment of biobatteries via a synthetic 15-enzyme pathway. The biobatteries generated maximum power densities from 0.65 to 0.98 mW cm^-2. Also, a nitrogen-doped activated carbon cloth was used as a flexible cathode to achieve oxygen reduction reaction faster than that catalyzed by platinum-coated membrane electrode assembly. Biobatteries comprised of 15 enzymes oxidize sucrose, fructose and glucose simultaneously, generated nearly 24 electrons per hexose with faraday efficiencies of approximately 95%. Metal-free biobatteries powered by commercial soft drinks whose energy-storage density was ~400 Ah kg^-1 of drinks exhibited maximum power densities of up to 0.55 mW cm^-2, implying that soft drinks could be perfect fuels for bioelectricity generation.