Current and clamping pressure distribution studies on the scale up issues in direct methanol fuel cells

The focus of the present study is to obtain the performance on a larger area (45 cm2) equivalent to that obtained on a smaller area (4 cm2) single cell DMFC overcoming performance losses associated with scale-up of single cell DMFCs due to uneven clamping pressure distribution on MEA through the end-plates and non-uniform distribution of reactants to MEA. The current distribution profile along the cathode flow field channel is measured using a segmented current measurement plate to understand the influence of uneven clamping pressure distribution on the MEA. Uniform current distribution in a single cell DMFC with 45 cm2 electrode area is achieved using angular ribbed end-plates. Also, in the present study performance of conventional DMFC is compared with that of mixed-reactant (MR), i.e. methanol and air. Performance of DMFC operating on mixed reactant (MeOH + air) at anode and air at cathode is superior compared with DMFC operating on aqueous methanol at anode and air at cathode. A power density of 55 mW cm−2 at 0.3 V is obtained for a DMFC single cell with an effective area of 45 cm2 using angular ribbed end-plates and MR at anode and air at cathode under ambient conditions. Pressure film test is conducted to obtain the clamping pressure distribution and cyclic voltammetry is performed to obtain the electrochemical surface area of small and large area electrodes.