A woven thread-based microfluidic fuel cell with graphite rod electrodes

Abstract

A woven thread-based microfluidic fuel cell based on graphite rod electrodes is proposed. Both inter-fiber gaps and inter-weave spaces could provide flow channels for the liquid transport through the woven cotton thread. Therefore, no external pumps are required to maintain the co-laminar flow, benefiting for the integration and miniaturization. In the experiment, sodium formate and hydrogen peroxide are used as fuel and oxidant, respectively. To improve the electrochemical reaction kinetics, KOH and H2SO4 serve as supporting electrolyte at the anode and cathode, respectively. Na2SO4 solution is used as the electrolyte to separate the cathode and anode in the middle flow channel and alleviate the reactant crossover. The open circuit potential of the fuel cell achieves 1.44 V and the maximum current density and power density are 56.6 mA cm−2 and 20.7 mW cm−2, respectively. Moreover, the cell performance reduces with increasing the electrode distance due to a high ohmic resistance. With an increase in the fuel concentration from 1 M to 4 M, the performance increases and it reduces with further increasing to 6 M owing to a correspondingly low flow rate. The highest fuel utilization rate reaches 10.9% at 4 M fuel concentration.