Structural optimization of (La, Sr)CoO3-based multilayered composite cathode for solid-oxide fuel cells

Park, Sunyoung; Ji, Hyunjin; Kim, Hae-Ryoung; Yoon, Kyung Joong; Son, Ji‐Won; Kim, Byung-Kook; Je, Hae-Jun; Lee, Hae-Weon; Lee, Jong-Ho

doi:10.1016/j.jpowsour.2012.11.108

Cited by 11 publications

(5 citation statements)

References 37 publications

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“…This is plausible since the high-frequency domain is associated with oxygen ion transport at the cathode/electrolyte interface; this ion transport is referred to as the charge transfer process. 47,48 In this study, the CoO x treatment results in changes in the impedance at frequencies lower than 1 kHz; the modification should therefore, degrade the surface exchange property of the cathode including the non-charge transfer process. 46 The higher activation energy of the ASR pol of the CoO x -treated cell, compared to that of the bare cell (Figure 7), can be attributed to the degradation of surface exchange characteristics owing to modification.…”

Section: Resultsmentioning

confidence: 87%

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

Choi

Bae

Jang

et al. 2015

J. Electrochem. Soc.

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In the present study, the surface of La 0.6 Sr 0.4 CoO 3 (LSC) was modified via atomic layer deposition (ALD) using CoO x as the modification material. The effect of the ALD CoO x treatment on the LSC-based anode-supported solid oxide fuel cell was analyzed and the ALD CoO x -treated cell was found to exhibit lower power density than that of the bare cell. Based on the electrochemical impedance spectroscopy measurements, it was concluded that this degradation stems mainly from the increased polarization loss, which results from the deterioration of the oxygen surface exchange property. Similarly, examining the bode plot revealed that the impedance at frequencies lower than 1 kHz increased mainly after the CoO x treatment; this increased impedance is believed to be associated with the limitation of O 2 adsorption and dissociation. Conventional solid oxide fuel cells (SOFCs) are operated at high temperatures (≥800• C) in order to ensure rapid kinetics and fast ion transport.1 However, lower operating temperatures are required to decrease the thermal budget and guarantee long time stability.2 For this reason, thin film electrolyte SOFC systems such as μ-SOFCs, were proposed and reported to have high power density owing to low ohmic loss.3-8 The performance of SOFCs at low temperatures (<650 • C) is hindered by the sluggish kinetics of the cathode.9,10 Therefore, developing a cathode which exhibits low polarization loss is essential to further improving this performance. Various mixed ionic electronic conducting (MIEC) ceramics such as La 1-x Sr x CoO 3-δ (LSC), La 1-x Sr x FeO 3-δ (LSF), and La 1-x Sr x Co 1-y Fe y O 3-δ (LSCF) have been proposed as cathode materials for low-temperature operation of the SOFC. [11][12][13] The charge transport at the MIEC cathode consists of five steps: (1) oxygen adsorption and dissociation; (2) oxygen ionization; (3) oxygen ion incorporation; (4) bulk diffusion; (5) oxygen ion transfer at the cathode/electrolyte interface. Among these processes, the surface kinetics, which includes steps (1) to (3), is typically considered as the rate-determining step rather than a stage involving bulk oxygen ion conduction. [14][15][16] Composite cathodes, which are fabricated by mechanically mixing different materials, can lead to improved cathode performance. Although electrolyte materials such as yttria-stabilized zirconia (YSZ) have been widely used as additives in forming the composite cathodes, transition metal oxides such as cobalt oxide can also be added. 17A surface modification technique has recently been introduced as an alternative method of increasing the catalytic activity of SOFC cathodes. In contrast to the composite cathode strategy, surface modification ensures adhesion between the cathode and electrolyte without the use of high sintering temperatures.18 Surface modification of the backbone cathode with a nanoparticle or thin film has been suggested as one means of enhancing the surface kinetics. Furthermore, the addition of ceramic nanoparticles or a thin film to the SOFC cath...

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Section: Resultsmentioning

confidence: 87%

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

Choi

Bae

Jang

et al. 2015

J. Electrochem. Soc.

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“…The range of the postannealing temperatures was determined to be higher than the deposition temperature and near, but not too much higher than, the sintering temperature of the powder-processed cathode (950 • C). 20 The surface morphology and the cross-sectional microstructure were observed by using scanning electron microscopy (SEM, XL-30, FEI, Netherlands). For the specimen annealed at 1000 • C, epoxy was used to fill up the pores, and the focused ion beam (FIB, Nova 600, FEI, Netherland) milled cross-sectional image was acquired to identify each material and to investigate the formation of the interconnectivity of the different materials in the composite cathode in more detail.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Post-Annealing on the Properties of a Pulsed-Laser-Deposited La_0.6Sr_0.4CoO_3-δ-Ce_0.9Gd_0.1O_2-δNano-Composite Cathode

Park¹,

Hong²,

Kim³

et al. 2013

J. Electrochem. Soc.

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The effect of the post-annealing on the properties of the La 0.6 Sr 0.4 CoO 3-δ -Ce 0.9 Gd 0.1 O 2-δ (LSC-GDC) nano-composite cathode fabricated by pulsed laser deposition (PLD) is investigated. Implementing the post-annealing treatment at a temperature in the range of 800 • C ∼ 1000 • C enables the control of the grain size in the LSC-GDC over the range of several tens of nanometers to near one-hundred nanometers. Moreover, the post-annealing treatment improves the interconnectivity between the same materials and mitigates the vertical separation between the columnar domains, resulting in the reduction of the lateral conduction loss. In terms of the electrochemical properties, the cathodic activity of the post-annealed cathode appears to be reduced due to the reduction in the number of the surface reaction sites, which is a result of the post-annealing grain-size growth. Although this grain-size growth results less power output of the solid oxide fuel cell (SOFC) using a post-annealed LSC-GDC cathode relative to that of the SOFC using the as-deposited LSC-GDC cathode, the lifetime of the former at 650 • C is improved.

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“…Besides, to reduce the mechanical degradation from the thermal mismatch, we prepared SOFCs with cathode consisting of Ce 0.9 Gd 0.1 O 1.95 − La 0.6 Sr 0.4 CoO 3−δ cathode functional layer (CFL) and La 0.6 Sr 0.4 CoO 3−δ cathode current collecting layer (CCCL). 26 Finally, the electrochemical characteristics of IT-SOFCs with various morphologies of cathode layer were investigated using a microscopic and a spectroscopic analysis.…”

Section: Introductionmentioning

confidence: 99%

“…The microstructures of the cathode membrane as a function of deposition temperature ( T dep ) of ESD were analyzed, and the correlation with the thermal properties of the polymer dispersant was investigated. Besides, to reduce the mechanical degradation from the thermal mismatch, we prepared SOFCs with cathode consisting of Ce 0.9 Gd 0.1 O 1.95 − La 0.6 Sr 0.4 CoO 3−δ cathode functional layer (CFL) and La 0.6 Sr 0.4 CoO 3−δ cathode current collecting layer (CCCL) 26 . Finally, the electrochemical characteristics of IT‐SOFCs with various morphologies of cathode layer were investigated using a microscopic and a spectroscopic analysis.…”

Section: Introductionmentioning

confidence: 99%

Crack‐free cathode of intermediate‐temperature solid oxide fuel cells via electrospray deposition

Kim

Son

et al. 2021

Int J Applied Ceramic Tech

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Cracks and delamination primarily revealed in the microscale‐thick cathode have been known as the major cause of increasing the polarization resistance and inhibiting the low‐temperature operation of solid oxide fuel cells (SOFCs). Besides, these defects were originated from the polymer dispersant, essential for the fabrication of the bulk cathode layer. Herein, we manufactured a crack‐free cathode layer by optimizing the deposition temperature (Tdep) of the powder‐suspension electrospray deposition (ESD) process through thermal characterization of polyvinylpyrrolidone (PVP), a polymer used in the slurry of ESD. SOFCs with the cathode deposited at the glass transition temperature of PVP resulted in a maximum power density of 0.481 W/cm2, 37% and 39% improved than those with the cathode deposited at Tdep = 25 and 200℃, respectively, at 650℃. Furthermore, the effect of uniformly dispersed morphology of cathode without defects was demonstrated by the reduction of polarization resistance through electrochemical impedance spectroscopy analysis.

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Structural optimization of (La, Sr)CoO3-based multilayered composite cathode for solid-oxide fuel cells

Cited by 11 publications

References 37 publications

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

The Effect of Post-Annealing on the Properties of a Pulsed-Laser-Deposited La_0.6Sr_0.4CoO_3-δ-Ce_0.9Gd_0.1O_2-δNano-Composite Cathode

Crack‐free cathode of intermediate‐temperature solid oxide fuel cells via electrospray deposition

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Structural optimization of (La, Sr)CoO3-based multilayered composite cathode for solid-oxide fuel cells

Cited by 11 publications

References 37 publications

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

Performance Degradation of Lanthanum Strontium Cobaltite after Surface Modification

The Effect of Post-Annealing on the Properties of a Pulsed-Laser-Deposited La0.6Sr0.4CoO3-δ-Ce0.9Gd0.1O2-δNano-Composite Cathode

Crack‐free cathode of intermediate‐temperature solid oxide fuel cells via electrospray deposition

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Product

Resources

About

The Effect of Post-Annealing on the Properties of a Pulsed-Laser-Deposited La_0.6Sr_0.4CoO_3-δ-Ce_0.9Gd_0.1O_2-δNano-Composite Cathode