A Breakthrough in the Performance and Fuel Utilization of Methanol Microfluidic Fuel Cell via Viscous Co-flow Electrolyte

Abstract

<p>Microfluidic fuel cells (MFCs) employ laminar flows to eliminate the expensive polymer electrolyte membrane and overcome the various drawbacks caused by it. However, there is a trade-off between their electrochemical performance and fuel utilization, especially with methanol fuel due to its high diffusivity in water. Also, the power density and fuel utilization of existing methanol MFCs still need improvement. In this work, a MFC with an alkaline anolyte and acidic catholyte co-flow configuration was designed to achieve high open-circuit voltage and high power density. To better form a steady alkaline-acid co-flow interface and to suppress the methanol crossover, gelling polymers were added to increase the density and viscosity of the electrolytes. This reduced the flow rate required from hundreds to 25 μL min⁻¹. In this manner, not only the trade-off was resolved, but also the peak power density and fuel utilization were prominently promoted. The highest peak power density was nearly 43.5 and 90 mW cm⁻² at 25 and 100 μL min⁻¹, respectively, and the fuel utilization per pass was 7.5 times higher compared with that in the literature. Moreover, the cell robustness was greatly improved because of the viscous co-flow configuration.<br></p>