Design and simulation of a liquid electrolyte passive direct methanol fuel cell with low methanol crossover

This study investigates an aqueous solution of sulfuric acid that serves as the liquid electrolyte (LE) in a passive direct methanol fuel cell (DMFC). The addition of an LE can reduce methanol crossover and increase the fuel utilization significantly. To improve the performance of an LE-DMFC, a mathematical model is developed to optimize the thicknesses of both the LE layer and the Nafion membrane. The maximum power density of the LE-DMFC is improved by approximately 30% compared with a conventional DMFC (C-DMFC) when each is fed by methanol solutions of the same concentration. Due to the low methanol crossover of the LE-DMFC, a highly concentrated methanol solution can be directly fed into the LE-DMFC. The discharge time and volume energy density of the LE-DMFC are two times longer and three times greater than those of the C-DMFC, respectively. In addition, fuel utilization increases by approximately 100%.

► LE-DMFC has a 30% lager maximum power density than C-DMFC with the same methanol concentration. ► The LE-DMFC can be fed with high concentration methanol. ► The LE-DMFC can obtain an energy density higher than 110 Wh L−1. ► The LE-DMFC has a 100% higher fuel utilization than C-DMFC with the same methanol concentration.