Performance of Fuel Electrode-Supported Tubular Protonic Ceramic Cells Prepared through Slip Casting and Dip-Coating Methods

Fuel electrode-supported tubular protonic ceramic cells (FETPCCs) based on the BaZr0.4Ce0.4Y0.15Zn0.05O3-delta (BZCYZ) membrane electrolyte was fabricated through a two-step method, in which the polyporous electrode-support tube was prepared with a traditional slip casting technique in a plaster mold, and the BZCYZ membrane was produced by a dip-coating process on the outside surface of the electrode-support tube. The dense thin-film electrolyte of BZCYZ with a thickness of similar to 25 mu m was achieved by cofiring the fuel electrode support and electrolyte membrane at 1450 degrees C for 6 h. The electrochemical performances of the FETPCCs were tested under different solid oxide cell modes. In protonic ceramic fuel cell (PCFC) mode, the peak power densities of the cell reached 151-191 mW center dot cm(-2) at 550-700 degrees C and exhibited relatively stable performance during continuous operation over 100 h at 650 degrees C. It was found that the major influence on the performance of tubular PCFC was the resistance and cathode current collectors. Additionally, in protonic ceramic electrolysis cell (PCEC) mode, the current densities of 418-654 mA center dot cm(-2) were obtained at 600-700 degrees C with the applied voltage of 2.0 V when exposed to 20% CO2-80% H-2 and 3% H2O/air. Using distribution of relaxation time analysis, the electrolytic rate-limiting step of the PCEC model was determined as the adsorption and dissociation of the gas on the electrode surface.