Improving the performance of direct methanol fuel cells by implementing multilayer membranes blended with cellulose nanocrystals

Methanol crossover through the proton exchange membranes of a direct methanol fuel cell (DMFC) significantly affects its performance and efficiency. Low methanol permeability and high proton conductivity of the membrane is desired for optimum performance. In this work, a multilayer (ML) membrane configuration prepared by a simple pressing technique is employed with and without the incorporation of sprayed cellulose nanocrystals (CNC) to achieve enhanced membrane properties. Assembled multilayer electrolytes show 19% enhanced maximum power density, while the addition of 1.5 wt% CNC (wt % of total final membrane) further improves the performance, giving a 38% better performance compared to standard Nafion N115. Methanol flux density and electrochemical impedance measurements attribute these improvement to the ~20% enhancement in the proton conductivity for the multilayer membrane which is enhanced further by an 11% reduction in methanol crossover when the cellulose nanocrystals are added.