Membranelss micro fuel cell chip enabled by self-pumping of fuel-oxidant mixture

Despite the significant research in micro fuel cells, miniaturizing a whole fuel cell system to below a few millimeters did not appear feasible until very recently, because ancillary parts (e.g. external pump, gas separator) are needed to complete a self-standing system. Building on the recently discovered self-pumping fuel cell free of the ancillary parts, here we design and test new self-pumping fuel cell architecture free of the membrane electrode assembly (MEA). Benefiting from the selectivity of catalysts on each electrode under slow flow rates, we find that the device can be run in a mixed stream instead of the two streams of unmixed laminar flows of fuel and oxidant, greatly simplifying the design. Proof-of-concept device verifies the mechanism of embedded fuel pumping and CO₂ degassing, while producing 8 mW/cm² of peak power density.