Performance of a glucose-driven bio-battery was improved by enhancing electrode characteristics and oxygen supply efficiency to a cathode. The bio-battery generates electric power from glucose through three enzymatic reactions using glucose dehydrogenase, diaphorase and bilirubin oxidase. A flexible and thin Pt electrode was employed instead of a glassy carbon (GC) electrode on which enzymes, a coenzyme, and mediators were immobilized by layer-by-layer method. The maximum current and power densities of the constructed bio-battery were 257 ± 22 μA/cm 2 and 86 ± 3 μW/cm 2 , respectively, in 5 mM glucose solution. In addition, a newly designed compact gas/liquid diaphragm cell, which allowed to reduce the internal resistance by shortening the anode-cathode distance and enhance oxygen supply to a cathode using a highly-porous cotton mesh diaphragm, was implemented to the bio-battery to develop a high-performance Air bio-battery. As a result, improved Air bio-battery showed the maximum current and power densities of 451 ± 27 μA/cm 2 and 162 ± 7 μW/cm 2 , which was 3.6-fold improvement from the previous GC electrode-based bio-battery. In addition, continuous operation for 210 min revealed high stability of power generation as it decreased by 3.3% at the end of operation. Additional supply of oxygen to a cathode exhibited proportional increase of the power density to the oxygen concentration, which demonstrates a promising potential of Air bio-battery for a high-performance and continuous powering device.
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