Abstract
High-energy-density, green, safe batteries are highly
desirable for meeting the rapidly growing needs of portable electronics. The
incomplete oxidation of sugars mediated by one or a few enzymes in enzymatic
fuel cells suffers from low energy densities and slow reaction rates. Here we
show that nearly 24 electrons per glucose unit of maltodextrin can be produced
through a synthetic catabolic pathway that comprises 13 enzymes in an
air-breathing enzymatic fuel cell. This enzymatic fuel cell is based on
non-immobilized enzymes that exhibit a maximum power output of 0.8 mW cm−2 and
a maximum current density of 6 mA cm−2, which are far higher than the values
for systems based on immobilized enzymes. Enzymatic fuel cells containing a 15%
(wt/v) maltodextrin solution have an energy-storage density of 596 Ah kg−1,
which is one order of magnitude higher than that of lithium-ion batteries.
Sugar-powered biobatteries could serve as next-generation green power sources,
particularly for portable electronics.