Low Temperature Voltage Driven Oxygen Membranes and Solid Oxide Fuel Cells

Abstract

For NAMS 2018 Annual Meeting

June 9-13, Lexington, Kentucky

Oral Session: Membranes for Energy Applications Low Temperature Voltage Driven Oxygen Membranes and Solid Oxide Fuel Cells

Ralph A. Bauer and Hendrik Verweij

Department of Materials Science and Engineering, The Ohio State University

2041 College Rd, 291A Watts Hall, Columbus OH 43210, USA.

(: +1 (614) 805-3015, +1 (510) 847-2372, +1 (614) 247-6987

E-mail: Bauer.348@buckeyemail.osu.edu, and Verweij.1@osu.edu

The high cost price of pure O₂ is an important component of the overall costs in chemical processes, steel manufacturing food processing, water treatment, medical applications and the projected operation cost of new fossil fuel power plants. The production of O₂ by non-isothermal cryogenic oxidation is time, energy, and material intensive, with costs reaching asymptotic limits. Iso-thermal electrochemical O₂ pumping efficiencies can approach thermodynamic limits, provided irreversible losses are minimized. For practical reasons, limiting operating temperatures to well below 500°C is preferable. Recently we demonstrated a thin film solid oxide fuel cells (SOFC) that operated at <500°C with good efficiency. This SOFC when operated in reverse mode, functioned as an O₂ pump. Electrochemical pumping behavior was observed down to 200°C. The SOFC nano-layered structure was then optimized for oxygen pumping, by refining nano-particle dispersions, and reducing the layer thicknesses. Thin-film O₂ pump modules, consisting of ~200 nm thick, homogenous electrode and electrolyte layers were fabricated on porous α‑Al₂O₃ supports by depositing nano-particle dispersions followed by rapid thermal processing. O₂ pumping air and O₂ feeds were introduced to the cathode side and an N₂ permeate sweep flushed the anode side. O₂ permeate concentrations were analyzed with a Nernst cell. By optimizing the layer structures, the oxygen flux was drastically increased and electrochemical oxygen pumping behavior was observed at temperatures as low as 125°C.