The proton exchange membrane fuel cell (PEMFC) requires an “activation” process to optimize its function to a consistent level. This paper offers a comprehensive exploration of the fundamental principles, activation techniques, and characterization methods involved in the activation process. Initially, existing literature is reviewed to identify activation mechanisms, with a focus on modifying the membrane electrode assembly (MEA) morphology. This includes adjusting factors like catalyst layer porosity, catalyst activity, shape, size, and chain orientation of polymers. Various activation methods are then analyzed, including pre-activation by steam, plasma, acid, or compression. Conditions such as dynamic operation, high pressure/temperature, and supersaturation are found to enhance activation kinetics. For automotive PEMFC stacks, meeting producer-specified rated beginning-of-life (BOL) performance is crucial prior to integration into vehicles. This discussion covers progress in reducing conditioning times, often to 4 h or less, without the need for additional inert gases. It examines techniques for creating oxidizing and reducing conditions through approaches such as cathode starvation, cyclic voltammetry, short circuiting, or switching reactants. The paper also discusses the limitations of traditional activation characterization methods, emphasizing the need for enhanced reproducibility through modern electrochemical characterization, postmortem analysis, and the examination of cell output species.
