Analytical electrolyzer enabling operando characterization of flow plates

We present an analytical electrolyzer with sensors embedded within flow plates to enable direct measurement of electrolyte temperatures and pressures in real time during water electrolysis. Flow plates with either parallel or serpentine channels and a total of eight equally spaced sensors were integrated into a flow cell containing a nickel foam gas diffusion layer and an anion exchange membrane. The temperature and pressure of the electrolyte in the channels increase relative to the inlet by as much as 7.3 °C and 11.5 kPa, respectively, during electrolysis at an applied current density of 200 mA cm⁻². The measured increases in temperature and pressure differ depending on the flow plate geometry: A greater increase in temperature is observed in parallel flow plates, whereas the serpentine flow plate geometry results in greater variability in pressure. This work represents the first demonstration of an analytical flow cell capable of spatially resolved operando temperature and pressure sensing within the flow channels of a water electrolyzer.