Revealing the dynamic temperature of the cathode catalyst layer inside proton exchange membrane fuel cell by experimental measurements and numerical analysis.

• A homemade microsensor measures CCL dynamic temperature. • An improved transient thermal model is developed to analyze the process. • Both experiment and simulation indicate 0–7 °C temperature variation. • Temperature variation is dramatically affected by cathode operation. • Underlying mechanisms for temperature variation are analyzed. Temperature variation inside the cathode catalyst layer (CCL) is significant, which could greatly damage fuel cell performance and durability. However, limited by CCL microstructure and complex physicochemical processes, the knowledge regarding CCL dynamic temperature is indeed insufficient. Thus, this work integrates a pre-prepared thin-film microsensor into the fuel cell to measure CCL surface temperature under dynamic load. At the same time, an improved transient thermal model considering local mass transport and liquid effect on thermal contact resistance (TCR) is established for the first time to analyze the internal process. Results show that CCL temperature is greatly affected by local resistance and interface accumulated water. And, as confirmed by both experiment and simulation, the CCL surface exhibits 0–7 °C temperature variation, whose profile changes sharply at the beginning and then evolutes slowly, eventually taking tens or hundreds of seconds to reach a new steady state due to thermal inertia. Moreover, the temperature is further increased by ∼1 °C as cathode humidity increases or stoichiometric ratio decreases, but only slight changes with the anode condition. The significant role of cathode operation is attributed to the greater mass transfer resistance and more sensitive intrinsic oxygen reduction reaction to reactant change. This study is expected to provide a deeper understanding of CCL dynamic temperature, thus improving fuel cell thermal management. [ABSTRACT FROM AUTHOR]