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Microstructure and Microfabrication Considerations for Self‐Supported On‐Chip Ultra‐Thin Micro‐Solid Oxide Fuel Cell Membranes
Author(s) -
Lai B.K.,
Xiong H.,
Tsuchiya M.,
Johnson A. C.,
Ramanathan S.
Publication year - 2009
Publication title -
fuel cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.485
H-Index - 69
eISSN - 1615-6854
pISSN - 1615-6846
DOI - 10.1002/fuce.200800144
Subject(s) - materials science , microstructure , microfabrication , thin film , solid oxide fuel cell , yttria stabilized zirconia , membrane , annealing (glass) , chemical engineering , nanocrystalline material , cathode , oxide , composite material , cubic zirconia , nanotechnology , ceramic , metallurgy , fabrication , electrode , chemistry , medicine , alternative medicine , engineering , pathology , biology , anode , genetics
La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 – δ (LSCF) has been sputtered on bare Si and Si 3 N 4 and yttria‐stabilised zirconia (YSZ) thin films to investigate annealing temperature‐ and thickness‐dependent microstructure and functional properties, as well as their implications for designing failure‐resistant micro‐solid oxide fuel cell (μSOFC) membranes. The LSCF thin films crystallise in the 400–450 °C range; however, after annealing in the 600–700 °C range, cracks are observed. The formation of cracks is also thickness‐dependent. High electrical conductivity, ∼520 Scm –1 at 600 °C, and low activation energy, ∼0.13 eV, in the 400–600 °C range, are still maintained for LSCF films as thin as 27 nm. Based on these studies, a strong correlation between microstructure and electrical conductivity has been observed and an annealing temperature‐thickness design space that is complementary to temperature‐stress design space has been proposed for designing reliable membranes using sputtered LSCF thin films. Microfabrication approaches that maintain the highest possible surface and interface quality of heterostructured membranes have been carefully examined. By taking advantage of the microstructure, microfabrication and geometrical structural considerations, we were able to successfully fabricate large‐area, self‐supported membranes. These results are also relevant to conventional or grid‐supported SOFC membranes using ultrathin nanocrystalline cathodes and μSOFCs using cathode thin films other than LSCF.