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

Abstract

Fuel electrode-supported tubular protonic ceramic cells (FETPCCs) based on the BaZr0.4Ce0.4Y0.15Zn0.05O3−δ (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 ~25 μm was achieved by cofiring the fuel electrode support and electrolyte membrane at 1450 °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·cm−2 at 550–700 °C and exhibited relatively stable performance during continuous operation over 100 h at 650 °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·cm−2 were obtained at 600–700 °C with the applied voltage of 2.0 V when exposed to 20% CO2–80% H2 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.

Recent Advances and Challenges in Thin-Film Fabrication Techniques for Low-Temperature Solid Oxide Fuel Cells

“…These relatively simple techniques have been extensively used as cost-effective and flexible fabrication methods in fabricating electrolyte layers with thicknesses as small as a few tens of microns to more than 200 µm. Dip coating, also known as slurry coating, has been used as a simple method to deposit thin electrolyte layers in both planer and tubular SOFCs [376][377][378]. In most wet ceramic coating methods, a slurry consisting of a solvent (i.e., ethanol or an azeotropic mixture of toluene), dispersant (i.e., menhaden fish oil or phosphate ester), binder (i.e., polyvinyl alcohol or polyvinyl butyral), and fin ceramic powder (e.g., YSZ or GDC) is used to coat a porous substrate, e.g., anode or cathode [379].…”