Tak-Hyoung Lim

Carbon-free cobalt oxide cathodes with tunable nanoarchitectures for rechargeable lithium–oxygen batteries

Carbon-free cobalt oxide cathodes for lithium-oxygen batteries are fabricated via an electrodeposition-conversion process. The Co3O4-only cathodes show a remarkably reduced voltage gap (by ca. 550 mV compared to the carbon-only cathode) as well as excellent long-term cyclability.

Correlation between fast oxygen kinetics and enhanced performance in Fe doped layered perovskite cathodes for solid oxide fuel cells

Many researchers have recently focused on layered perovskite oxides as cathode materials for solid oxide fuel cells because of their much higher chemical diffusion and surface exchange coefficients relative to those of ABO3-type perovskite oxides. Herein, we study the catalytic effect of Fe doping into SmBa0.5Sr0.5Co2O5+δ on the oxygen reduction reaction (ORR) and investigate the optimal Fe substitution through an analysis of the structural characteristics, electrical properties, redox properties, oxygen kinetics, and electrochemical performance of SmBa0.5Sr0.5Co2−xFexO5+δ (x = 0, 0.25, 0.5, 0.75, and 1.0). The optimal Fe substitution, SmBa0.5Sr0.5Co1.5Fe0.5O5+δ, enhanced the performance and redox stability remarkably and also led to satisfactory electrical properties and electrochemical performance due to its fast oxygen bulk diffusion and high surface kinetics under typical fuel cell operating conditions. The results suggest that SmBa0.5Sr0.5Co1.5Fe0.5O5+δ is a promising cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs).

La 0.8 Ca 0.2 CrO 3 Interconnect Materials for Solid Oxide Fuel Cells: Combustion Synthesis and Reduced-Temperature Sintering

Sub-micrometer powders for ceramic interconnects of solid oxide fuel cells were synthesized by the aqueous combustion process. The materials were prepared from the precursor solutions with different glycine (fuel)-to-nitrate (oxidant) ratios (). Single-phase powders with a perovskite structure were obtained after combustion when was equal to or larger than 0.480. Especially, the stoichiometric precursor with

Development of Tubular Solid Oxide Fuel Cells with Advanced Anode Current Collection

In this study, tubular SOFC unit cell with advanced anode current collector was fabricated to improve the cell performance. First, we prepared two types of single cells having the same manufacture processes such as the same electrolyte, electrode coating condition and sintering processes. And then to compare the developed single cell performance with conventional cells, we changed the anode current collecting methods. From the impedance analysis and I-V curve analysis, the cell performance of advanced cell is much higher than that of conventional cell.

Fabrication and Electrochemical Characterization of LSM/GDC based Cathode Supported Direct Carbon Fuel Cells

In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at . The porous structure of LSM/GDC cathode substrate, after sintering at , was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V, independent of testing temperature. The peak power densities were 116, 195 and at 750, 800 and , respectively.

Fabrication and Performance Evaluation of Tubular Solid Oxide Fuel Cells Stack

In present work, optimized the manufacturing process of anode-supported tubular SOFCs cell and stack were studied. For this purpose, we first developed a high performance tubular SOFC cell, and then made electrical connection in series to get high voltage. The gas sealing was established by attaching single cells to alumina jig with ceramic bond. Through these process, we can obtain such high OVP as around 15V, which means that the electrical connection and gas sealing were optimized. Finally we developed a new tubular SOFC stack which shows a maximum power of 65W @ 800℃.

Quantitative Microstructure Analysis to Predict Electrical Property of NiO-YSZ Anode Support for SOFCs

Abstract >> The correlation between NiO-YSZ microstructure and its electrical property used for SOFC anode was critically evaluated with image processing and direct measurement techniques. These innovative processing techniques were employed to quantify the contiguity of the anode constituent phase. The calculated contiguitieswere then correlated with electrical conductivity attained from 4-probe DC method. This investigation describedthat contiguity of nickel oxide phases of an anode has a linear relationship with its electrical conductivity. We observed that the contiguity of NiO increased from 0.18 to 0.50 then electrical conductivity attained was significantly increased from 520 S/cm to 1468 S/cm at 900°C. Key words : SOFC(고체산화물연료전지), Microstructure(미세구조), Anode(연료극), NiO-YSZ, Contiguity(연결도), PMMA † Corresponding author : sblee@kier.re.kr [ 접수일 : 2013.6.14 수정일 : 2013.6.28 게재확정일 : 2013.6.30 ]Copyright ⓒ 2012 KHNES 1. Introduction Anode support for a solid oxide fuel cells (SOFCs) is desired to have high electrical conductivity and mechanical stability at its operating temperature range (650 – 1000°C)

Development of LSM-Coated Crofer Mesh for Current Collectors in Solid Oxide Fuel Cells

A Crofer 22 APU mesh coated with a conductive ceramic material was developed as an alternative cathode current collector to Ag-based materials for solid oxide fuel cells. (LSM) layer was deposited onto the Crofer mesh using a spray-coating technique, in an attempt to mitigate the degradation of electrical properties due to surface oxidation at high temperatures. The oxidation experiments at in air indicated that the areaspecific resistance (ASR) of the LSM-coated Crofer mesh was strongly dependent on the wire diameter and the contact morphology between mesh and cell. In addition, the post-heat-treatment in resulted in a reduced thickness of Cr-containing oxide scales at the interface between Crofer mesh and LSM layer, leading to a decreased ASR.

Synthesis and Characterization of La 0.75 Sr 0.25 FeO 3 Used as Cathode Materials for Solid Oxide Fuel Cell by GNP Method

We synthesized and investigated by Glycine Nitrate Process(GNP) method used as cathode materials for SOFC(solid oxide fuel cell). Optimized amount of glycine is 3.17 mol. ICP elemental composition analysis indicated that the stoichiometry of the synthesized powders have nearly nominal values. SEM images and XRD patterns reveal that the synthesized powder has uniform size distribution and high degree of crystallinity. The sample powders were isostatically pressed to form a pellet. The green body was sintered at and the relative density of the sintered specimens were measured by Archimedes mettled. We measured electrochemical performance of LSF by AC impedance spectroscopy. Resistance of LSF shows lower value than that of LSM throughout all temperature region. The anode-supported solid oxide fuel cell showed a performance of at . The electrochemical characteristics of the single cell were examined by at impedance method.

Fabrication and Performance of Anode-Supported Flat Tubular Solid Oxide Fuel Cell Unit Bundle

KIER has been developing the anode-supported flat tubular solid oxide fuel cell unit bundle for the intermediate temperature() operation. Anode-supported flat tubular cells have Ni/YSZ cermet anode support, 8 moi.% stabilized thin electrolyte, and cathode multi-layer composed of Sr-doped , LSM-YSZ composite, and . The prepared anode-supported flat tubular cell was joined with ferritic stainless steel cap by induction brazing process. Current collection for the cathode was achieved by winding Ag wire and paste, while current collection for the anode was achieved by using Ni wire and felt. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of connected in series with 12 unit bundles, in which unit bundle consists of two cells connected in parallel. The performance of unit bundle in 3% humidified and air at shows maximum power density of (@ 0.7V). Through these experiments, we obtained basic technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular cell unit bundle.