Solid oxide carbonate composite fuel cells: Size effect on percolation. (26th November 2016)

• Record Type: Journal Article
• Authors: Shawuti, Shalima; Gülgün, Mehmet Ali
• Is Part Of: International journal of hydrogen energy. Volume 41:Number 44(2016)
• Page Start: 20343
• Page End: 20349
• Publication Date: 2016-11-26
• Subjects: Composite electrolyte -- SOFC -- Interface -- Percolation -- Carbonate -- Impedance; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2016.07.208
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In the studies of solid oxide carbonate composite fuel cell, percolation behaviour of the two phases was investigated as a function of particle size of the oxide phase. The ratio of amount of samarium doped ceria (SDC; Sm0.2 Ce0.8 O) to Na2 CO3 was varied to determine an optimum ionic conductivity as function of oxide particle size. The roles of both phases in the composite electrolyte were investigated. SDC particles were mixed in different amounts of Na2 CO3 to obtain composites with carbonate ratios from 1 wt% to 50 wt%. Micro-structural investigations showed that Na2 CO3 phase served as the matrix in the micro-structure gluing the oxide particles together. The lowest and the highest carbonate ratios caused low conductivities in the composite as in these samples the 3D connectivity of both phases were disrupted. Low conductivity at both ends of the mixture composition could be interpreted as none of the components of the composite dominated the ionic conductivity. The highest conductivity was obtained at 10 wt% Na2 CO3 amount in the composite electrolyte when nano-sized SDC (5–10 nm) oxide powders were used. Two different particle sizes of SDC powders were used to show that the optimum phase ratio, i.e. percolation of both phases, is function of particle size as well. The conductivity in the composite showed percolation behaviour with respect to the two constituent phases. Highlights: The percolation behaviour of oxide carbonate composite fuel cell was investigated. The ratio of SDC to Na2 CO3 was varied to find the optimum ionic conductivity. The low and the high carbonate ratios caused low conductivities in the composite. The conductivity showed the percolation behaviour with respect to the particle size.