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Title:	Enhancement of La0.6Sr0.4zCo0.2Fe0.8O3-g cathode material properties for solid oxide fuel cells
Authors:	Muhammad Ali S.A. (P74276)
Supervisor:	Andanastuti Muchtar, Dr.
Keywords:	Solid oxide fuel cells Fuel cells -- Materials Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	4-Oct-2018
Description:	A mixed ionic-electronic conducting oxide is widely explored as a high-performance cathode for intermediate-temperature solid oxide fuel cells (IT-SOFC). In particular, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) is the most suitable cathode material because of its higher surface catalytic activity toward the oxygen reduction reaction (ORR). However, the LSCF cathode performance is considerably influenced by the microstructural properties of the synthesised powders and sintered layers. Therefore, LSCF cathode microstructures need to be optimised by identifying an appropriate synthesis technique and fabrication conditions. Thus, the main aim of this work is to enhance the electrochemical properties of the LSCF cathode by adopting three different strategies to improve its microstructure. The first strategy is to identify the right choice of synthesis technique to prepare LSCF cathode powder with fine microstructure. Four different synthesis techniques are used in this work namely rotary evaporation, conventional oven assisted glycine nitrate process (GNP), hotplate assisted GNP and microwave assisted GNP. The results indicated that the phase formation and microstructure are strongly dependent on the nature of the synthesis methods used. A pure LSCF powder at lower calcination temperature (800 °C) with high BET specific surface area of 12.2 m2/g and low area specific resistance (ASR) was obtained from the LSCF cathode prepared by microwave assisted-GNP. However, the performance of the LSCF cathode prepared from this method can be further improved by the choice of fabrication conditions to print the LSCF cathode layers, as a second strategy. The screen printing technique was used to fabricate the cathode symmetrical cell. An improved electrochemical performance was achieved with the following fabrication conditions for the LSCF cathode sintered layers: thickness, 54 μm; 65 wt. %, LSCF solid content; and 1100 °C, sintering temperature. These conditions resulted in relatively low ASR value of 0.029 Ω cm2 at an operating temperature of 800 °C. Compatibility of the LSCF cathode with samarium doped ceria (SDC) powders was investigated by mixing LSCF with SDC powders to prepare LSCF-SDC composite cathode. The addition of SDC to LSCF cathode powder was found to exert significant increase in the ASR value of the LSCF cathode. The ASR of the LSCF-SDC composite cathode increased to 0.48 Ω cm2 at 800 °C, which is 16 times higher than the LSCF cathode. As a third strategy, the electrochemical performance of LSCF-SDC composite cathode was improved by employing a thin LSCF current collecting layer to enhance the in-plane electronic conductivity on the surface of the composite cathode. Together with these strategies which focussed on enhancing the electrochemical performance of LSCF cathode, this work achieved a low ASR value of 0.025 Ω cm2 at 800 °C for the LSCF-SDC composite cathode by printing a thin LSCF cathode current collecting layer (5 μm). In conclusion, this study proved that the right choice of synthesis techniques and fabrication conditions strongly contributes to the enhancement of the LSCF cathode performance for ITSOFC applications.,Ph.D.,Certification of Master's / Doctoral Thesis" is not available"
Pages:	170
Call Number:	TK2933.S65M8435 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Fuel Cell Institute / Institut Sel Fuel

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