EFFECTS OF NiO LOADING AND PRE-CALCINATION TEMPERATURE ON NiO-SDCC COMPOSITE ANODE POWDER FOR LOW-TEMPERATURE SOLID OXIDE FUEL CELLS

Abstract

The microstructural and thermal characteristics of NiO-samarium-doped ceria carbonate (NiO-DCC) composite powders have been explored in terms of NiO loading and pre-calcination temperature. NiO-SDCC composite powders were intimately mixed via fast ball-milling using different NiO loadings (50-70 wt. %) and subjected to various pre-calcination temperatures (600-800°C). Subsequently, the pre-calcined powders were then used to fabricate composite pellets using a uniaxial press and sintered at a low temperature of 600°C. The crystalline phase, carbonate bonding, microstructure and thermal behaviour of the composite anode powders were investigated. The microstructure, porosity, and hardness of sintered composite pellets were also evaluated. All samples maintained their chemical compatibility and carbonate bonding after various processes. The findings indicated that the pre-calcination factor was more important than NiO loading in terms of powder and pellet morphologies as well as the thermal expansion behaviour. Moreover, the composite pellets prepared with composite powders pre-calcined at increasing temperatures exhibited an increase in porosity, but within an acceptable range (30-40 %). Overall, composite pellets fabricated with 50 wt. % NiO exhibited the optimum hardness values of 21-31 HV and the lowest thermal expansion of 12.2-12.7 × 10-6 K-1 .

Effect of SSC Loading and Calcination Temperature on The Phase and Microstructure Formation of SSC-SDCC Cathode

“…These observations are kept settlement within the acceptable range (32.3% to 38.7%) and have been reported earlier in the previous paper [21]. Ng et al, (2016) have suggested that the porosity of the cathode within 20% to 40% is recommended for enhancement of electrochemical performance for LTSOFC [14].…”

“…Meanwhile, prior research work revealed the presence of impurities or secondary phases from SSC such as strontium carbonate (strontionite), SrCO3, and strontium cobalt carbonate SrCoCO3 towards the structural stability and performance of LTSOFC need to be clearly investigated [14]. Identified SSC-SDC cathodes of SOFC become unstable in reduction atmospheres, which have been affected due to the occurrence of the decomposition process of SSC to strontium oxide (SrO) and samarium oxide (Sm2O3), throughout the performance.…”

Characteristics of Ag Element on LSCF-SDCC-Ag Composite Cathode for LTSOFC Potential Applications

“…From the observation, ascribed Ag as an additive element has been promoting on the better powder distribution with all the elements remain detectable and clearly perceived after the addition of 3 wt.% Ag content. Unfortunately, lithium (Li) elements accredited from the composite cathode of LSCF-SDCC and LSCF-SDCC-Ag were not discovered by the EDS analysis, due to low atomic mass property of lithium element [5]. The result discussed earlier has demonstrated that all the critical elements in LSCF-SDCC-Ag composite cathode powder have been homogeneously mixed and well-distributed powder has successfully achieved via HEBM method.…”

“…The homogeneity of elements is essential as each element contributes to the electrochemical reactions occurred in the cathode. HEBM method in this research has successfully produced the homogenously dispersed powders of LSCF-SDCC-Ag composite cathode [5,11].…”

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Recently, the addition of electrolyte material to cathode material resulted in the increased of the triple-phase boundary (TPB) (air/electrode/electrolyte) area, where the electrochemical reactions occurred. A mixed ionic and electronic conductors (MIECs), such as La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), is one of the potential candidates that has been utilized in this approach since LSCF has been recognized as one of the promising cathode material for SOFC [4][5].

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