ABSTRACT
Polymer membrane possessing proton (H+) conducting property is made of a thin sheet of polymeric materials containing an extensive network of hydrophilic nanopores on a hydrophobic domain. This membrane can be explored for the separation purpose through transportation of H+ preferentially to create obstruction against the passage of a fluid. Polymer electrolyte membrane determines the efficiency and durability of fuel cells (FCs); research on direct methanol FCs (DMFCs), in particular, has been an area of great interest during the past several years. However, the main focus of the reduction of the methanol crossover with a significant H+-conductivity could not be achieved. As a result, the primary goals of researchers are to accomplish high proton conductivity, low gas permeability, high mechanical and chemical stability, recyclability, and low polymer membrane cost.
Out of several membranes tried during the last few years, the Nafion membrane is the most popular for high H+ conductivity because of the existence of hydrophilic functionality associated with hydrophobic fluorocarbon backbone. But the higher cost, pH splitting, and bio-fouling are the limitations of this membrane, which have provoked researchers to find an alternative improved membrane. CPs like polyaniline (PANI) and polypyrrole (PPy) can be utilized for the construction of polymer electrolyte membranes for FCs. However, these membranes still possess limited conductivity, which can be improved by “doping” methods, resulting in composite conducting polymer membranes. CPs succeeded in offering a ray of hope and have attracted researchers to get engaged in the manipulation of this opportunity.
This chapter highlights a discussion on conducting polymers, specifically PANI and PPy, and their applications as polymer electrolyte membrane constituents. Further, their effect on methanol crossover, H+-conductivity, gas diffusion, and thermal stability of composite membrane for the practical applications of DMFC are also discussed.
Conducting polymers, membrane, fuel cells, methanol fuel cells
