Planar polymer electrolyte membrane fuel cells: powering portable devices from hydrogen
Polymer Electrolyte Membrane Fuel Cells (PEMFC) are often viewed as enablers of decarbonised energy systems since they transform hydrogen directly into electricity with water as the main by-product. The attraction for fuel cells is also in their versatility because they can be implemented across a wide range of applications from microelectronics to large scale power generation. Herein, we review recent progress on the design and fabrication of PEMFC with a special focus on their air-breathing planar configuration as this extends the possibility of PEMFC to thin and flexible designs. To date, the deployment of planar PEMFC highly depends upon scientific progress and technological solutions for cost reduction and long-term durability including the development of better proton conducting membranes and platinum-free catalysts to drive the oxygen reduction and hydrogen oxidation reactions efficiently. Long term durability is another challenge that can be addressed through the advancement of inexpensive and lightweight current collectors and highly efficient gas diffusion electrodes for better distribution of the reactants while maintaining an optimum hydration of the proton conducting membrane. Innovative fabrication methods for the various components of planar PEMFC as well as effective stack design and assembly are also critical for efficiency maximization, reproducibility and overall cost reduction.