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Synthesis and characterization of nanocomposite Ni-YSZ anodes by water-in-oil micro-emulsion for solid oxide fuel cells

Title
Synthesis and characterization of nanocomposite Ni-YSZ anodes by water-in-oil micro-emulsion for solid oxide fuel cells
Translated Title
W/O 마이크로에멀젼을 통한 나노컴퍼지트 Ni-YSZ 음극 제조와 고체산화물 연료전지의 성능 향상을 위한 알칼리 농도의 최적화
Authors
Jung, Yong Min
DGIST Authors
Jung, Yong Min; Lee, Kang TaK
Advisor(s)
Lee, Kang TaK
Co-Advisor(s)
Lee, Chan Woo
Issue Date
2017
Available Date
2017-01-18
Degree Date
2017. 2
Type
Thesis
Keywords
SOFCsNanocompositeNi-YSZW/O micro-emulsionAlkali concentrations고체산화물 연료전지나노복합체W/O 마이크로에멀젼알칼리 농도
Abstract
Homogeneously distributed nanocomposite Nickel oxide-yttria stabilized zirconia (NiO-YSZ) powders were synthesized by water-in-oil (W/O) micro-emulsion method for solid oxide fuel cells. The particles synthesized by W/O micro-emulsion procedure with the calcination temperature of 500 oC, showed fine microstructures with a particle size less than 50 nm. Electrochemical performances were improved by the nanocomposite anode synthesized by micro-emulsion, compared with the results obtained by the conventional anode. The maximum power density of a single cell with micro-emulsion synthesized Ni-YSZ anode showed a higher maximum power density, 359 mW cm-2, compared with that of a single cell composed of conventional Ni-YSZ anode, 204 mW cm-2, at the operating temperature of 850 oC. The electrode resistance of a single cell fabricated by micro-emulsion had a value of 0.44 Ω cm2, which was much smaller than the value of conventional cell, 1.14 Ω cm2, at the same operating temperature with I-V analysis. The enlarged TPB length obtained by the microemulsion synthesized Ni-YSZ anode composed of uniformly distributed nano-grains might be the reason of the improved electrochemical performance of a single cell. Further studies were done to optimize the micro-emulsion procedures for improved cell performances. Three types of micro-emulsion synthesized NiO-YSZ powders, W10N10, W5N15, W0N20, with different alkali concentrations, were discussed. Particle size of W0N20 decreased to 30nm compared with the value of W10N10, around 40nm. Moreover, specific surface area of W0N20 drastically increased to 42.27 m2/g, from the value of W10N10, 14.98 m2/g. However, the maximum power density of a single cell was not affected by the alkali concentrations. The electrode resistance of a single cell with W0N20 showed a higher value of 0.65 Ω cm2, compared with the value of a single cell with W10N10, 0.44 Ω cm2, at the open circuit voltage with the operating temperature of 850 oC, although the particle size of W0N20 is smaller than that of W10N10. The reduced TPB length caused by the agglomeration of too small particles might be the reason of the electrochemical performances of single cells. ⓒ 2017 DGIST
Table Of Contents
1. INTRODUCTION 1-- 2. RESEARCH BACKGROUND 3-- 2.1. FUEL CELLS 3-- 2.1.1. Definition and principle of fuel cells 3-- 2.1.2. Types of fuel cells 3-- 2.2. SOLID OXIDE FUEL CELLS (SOFCS) 4-- 2.2.1. Definition and properties of SOFCs 4-- 2.2.2. Properties of SOFC anode 4-- 2.2.3. Research trends of SOFC anode 5-- 2.3. MICRO-EMULSION 5-- 2.4. EFFECTS OF ALKALI CONCENTRATIONS 6-- 3. EXPERIMENTAL PROCEDURES 13-- 3.1. SYNTHESIS OF NIO-YSZ NANOCOMPOSITE POWDERS 13-- 3.2. FABRICATION OF AN ELECTROLYTE-SUPPORTED SINGLE CELL 14-- 3.3. CHARACTERIZATIONS AND ELECTROCHEMICAL PERFORMANCE TESTS 14-- 4. PREPARATION AND CHARACTERIZATION OF NI-YSZ NANOCOMPOSITE ANODE FOR SOLID OXIDE FUEL CELLS BY WATER-IN-OIL MICRO-EMULSION METHOD 18-- 4.1. INTRODUCTION 18-- 4.2. RESULTS AND DISCUSSION 19-- 4.2.1. Phase diagram of micro-emulsion method 19-- 4.2.2. Thermo-gravimetric analysis 19-- 4.2.3. Phase analysis 20-- 4.2.4. Morphology analysis 20-- 4.2.5. Electrochemical performances 21-- 4.3. CONCLUSIONS 22-- 5. EFFECTS OF ALKALI CONCENTRATIONS ON THE PROPERTIES OF NI-YSZ NANOCOMPOSITE ANODE PREPARED BY WATER-IN-OIL MICRO-EMULSION METHOD 35-- 5.1. INTRODUCTION 35-- 5.2. RESULTS AND DISCUSSION 36-- 5.2.1. Phase diagram of micro-emulsion method 36-- 5.2.2. Phase analysis 36-- 5.2.3. Morphology analysis 37-- 5.2.4. Electrochemical performances 37-- 5.3. CONCLUSIONS 38-- 6. CONCLUSION 47
URI
http://dgist.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002326558
http://hdl.handle.net/20.500.11750/1520
DOI
10.22677/thesis.2326558
Degree
Master
Department
Energy Systems Engineering
University
DGIST
Files:
Collection:
Energy Science and EngineeringThesesMaster


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