Large-area protonic ceramic cells for hydrogen purification

Large-area symmetrical protonic ceramic cells (PCCs) are fabricated and tested for electrochemical hydrogen pumping (EHP) applications. BaZr_0.1Ce_0.7Y_0.2O_3-δ (BZCY), one of the most popular proton-conducting materials, is selected as the electrolyte material. Two identical Ni(O)-BZCY electrodes are applied to either side of the electrolyte as the anode and cathode. The PCCs are characterized both in single-atmosphere at open circuit voltage (OCV, symmetrical cell testing) and in dual-atmosphere under current (EHP mode). The electrode polarization resistance (R_P) (per single electrode) under single-atmosphere testing is measured to be as low as 0.13, 0.07, 0.065 and 0.06 Ω cm² in 3% humidified 50H₂/50 N₂ at 650, 700, 750 and 800 °C, respectively. The distribution of relaxation times (DRT) analyses of the measured impedance spectra reveal that the cell resistance is dominated by the resistance of the dissociative adsorption of hydrogen processes at 650–700 °C or by that of the hydrogen diffusion at 750–800 °C. The cell shows good electrochemical performance and durability in EHP mode, demonstrating a hydrogen flux of 8.7 mL cm⁻² min⁻¹ at 1.33 A cm⁻² with a Faradaic efficiency of 90% for pumping pure hydrogen out of 3% humidified 50H2/50 N₂ at 650 °C.