Abstract
The use of platinum as a catalyst and the nonuniform distribution of current density inside a membrane electrode assembly result in high cost and low durability, which strongly hinders the wide adoption of proton exchange membrane fuel cells. For proton exchange membrane fuel cells operated at various loads, the required activities and mass transport rates are different because the reactant and product are nonuniformly distributed inside the membrane electrode assembly. Thus, a rational design for a membrane electrode assembly with a spatial distribution of functional components is helpful for reducing the usage of precious components, improving cell performance, and achieving uniform distributions of current density and heat. Herein, the graded design of the functional components in the gas diffusion layer, microporous layer, catalyst layer, and membrane along both the through-plane and in-plane directions within the membrane electrode assembly are reviewed for the purpose of reducing the cost and improving the performance and durability of proton exchange membrane fuel cells.
•A first review of functional graded design of MEA for PEM fuel cells was finished.•Functional components distributed along both trough-plane and in-plane directions.•Platinum, ionomer, porosity, hydrophobicity and SO42− group were investigated.•Species transport rate better matched intrinsic reaction rate by the graded design.•Provided a method of reducing cost and improving performance of PEM fuel cells.