Spray Pyrolysis Strategy for Preparation of Cathode-Supported Protonic Ceramic Fuel Cells

Abstract

Since the discovery of proton conducting ceramic materials many research efforts have been focused into overcoming processing difficulties that hinder long-term stability and high performance of protonic ceramic fuel cells (PCFCs). Notably, high processing temperatures exceeding 1600 °C are often required to meet the microstructural demand of a dense proton conducting electrolyte membrane [1-2]. At this temperature range most potential electrode materials are chemically incompatible and therefore preclude the fabrication of electrode supported structures. In addition, for barium-based electrolytes (e.g. BaZr1-xYxO3-d) barium loss is anticipated resulting in lower conductivities and formation of structural defects. To overcome this major challenge thin film deposition techniques can be employed[3-4].Spray pyrolysis is a cost effective and simple deposition technique for preparation of ultra-thin films (i.e.<5μm) enabling the reduction of operating and processing temperatures of fuel cells [5]. Microstructures and electrochemical performance of multi-layered thin film PCFCs fabricated at exceptional low temperatures of 950 °C, are investigated. Large area 5x5cm2 cathode substrates of (La0.8Sr0.2)0.95MnO3-d prepared by tape casting were used for mechanical support of the cells. To modify and reduce the surface porosity of the substrate Ce0.9Gd0.1O3-d was coated to facilitate the deposition of the BaZr0.9Y0.1O3-d (BZY) thin electrolyte. Subsequently, the anode electrode was sprayed in two stages comprised by a nano-porous layer of BZY and infiltrated Ni particles. Characterization of the cathode-supported PCFCs was performed by electrical measurements operating up to 600°C and scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) techniques.[1] Shanwen Tao and John T.S. Irvine, Adv. Mater., 18, 1581-1584, (2006).[2] Peter Babilo and Sossina M. Haile, J. Am. Ceram. Soc., 88 2362-2368, (2005).[3] Kiho Bae et al., Adv. Energy Mater., 8, 1801315, (2018).[4] Georgios Tsimekas et al., ECS J. Solid State Sci. Technol.,6(8), P553-P560, (2017).[5] Georgios Tsimekas et al., ECS Trans., 70(1), 205-212, (2015).