Insight into the internal mechanism and performance variation of a paper-based microfluidic fuel cell with longitudinal distribution of electrodes

This paper presents a three-dimensional numerical model for a paper-based microfluidic fuel cell with a distinctive structure. Unlike conventional side-by-side arrangements, the electrodes are longitudinally distributed, which effectively reduces ohmic resistance and enhances fuel transport. To elucidate the internal reaction mechanisms of this paper-based microfluidic fuel cell, the model integrates multiple physical fields, including Darcy’s law, mass transfer in porous medium, secondary current distribution. Additionally, both steady-state and transient simulations are employed to investigate the key factors influencing the performance and sensitivity of the cell. The numerical results align well with experimental data, validating the reliability and accuracy of the model. Based on the simulation findings, appropriately reducing the electrode width and increasing the electrolyte concentration can significantly enhance the output performance. In contrast, modifications to the channel thickness and electrode pair position primarily affect the stability and integration of the cell. At optimal performance, the corresponding peak power density, current density, and fuel utilization are 63.1 mW/cm2, 314.55 mA/cm2, and 3.92 %, respectively, surpassing most passive microfluidic fuel cells. Furthermore, the transient analysis reveals that a shorter inlet channel and paper with larger average pore sizes generally promote faster cell response.