• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.527-530
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• 2015

The electrical properties of nanostructured Gd-doped $CeO_2$ (n-GDC) as a function of temperature and water partial-pressure were investigated using ac and dc measurements. For n-GDC, protonic conductivity prevails under wet condition and at low temperatures (< $200^{\circ}C$), while oxygen ionic conductivity occurs at high temperatures (> $200^{\circ}C$) under both dry and wet conditions. The grain boundaries in n-GDC were highly selective, being conductive for protonic transport but resistive for oxygen ionic transport. The protonic conductivity reaches about $4{\times}10^{-7}S/cm$ at room temperature (RT).

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.71-74
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• 2010

We have investigated protonic conduction in highly dense (>98%) polycrystalline Y-doepd $BaZrO_3$ (BYZ) ceramic with an average grain size of ~85 nm. It is observed that the protonic conductivity across the grain boundaries in this nano-crystallilne BYZ (n-BYZ) is significantly higher than the microcrystalline counterpart. Such a remarkable enhancement in grain boundary conductivity results in high overall conductivity that may allow this chemically stable protonic conductor to serve as a solid electrolyte for low-temperature solid oxide fuel cell applications.

• Journal of Hydrogen and New Energy
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• v.35 no.1
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• pp.48-55
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• 2024

The electrochemically active site of mixed ionic and electronic conductor (MIEC) as a cathode material is restricted to the triple phase boundary in protonic ceramic fuel cells (PCFCs) due to the insufficient of proton-conducting properties of MIEC. This study primarily focused on expanding the electrochemically active site by La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ(LSCF6428)-BaZr_0.4Ce_0.4Y_0.1Yb_0.1O_3-δ (BZCYYb4411) composite cathode. The electrochemical properties of the composite cathode were evaluated using anode-supported PCFC single cells. In comparison to the LSCF6428 cathode, the peak power density of the LSCF6428-BZCYYb4411 composite cathode is much enhanced by the reduction in both ohmic and non-ohmic resistance, possibly due to the increased electrochemically active site.

• Polymer(Korea)
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• v.28 no.2
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• pp.149-153
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• 2004

The cesium hydrogen sulfate (CsHSO$_4$) crystal is a superprotonic conductor above 140$^{\circ}C$ and possesses protonic conductivity three to low orders of magnitude higher than that at room temperature. Recently, the possibility of it as an electrolyte material for fuel cell system draws much attention. However, its plasticity and absorption of humidity place a limitation on its application. In this study, composites consisting of CsHSO$_4$ and polyacrylonitrile were prepared, and their phase transition properties and the ionic conductivities were evaluated. When the content of CsHSO$_4$ was about 80 vol%, a mechanically strong film with the protonic conductivity of 1${\times}$10$\^$-3/ Scm$\^$-1/ were made.

• Bulletin of the Korean Chemical Society
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• v.23 no.8
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• pp.1144-1148
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• 2002

We prepared the polyaniline (Pani) film and powder by chemical polymerization and doping with different dopants and also investigated the capability of Li//polyaniline cells after assembling. The oxidation/reduction potentials and electrochemical reaction of Li//polyaniline cells were tested by cyclic voltammetry technique. The Li//Pani-HCl cells with 10% and 20% conductors show a little larger specific discharge capacities than that without conductor. The highest discharge capacity of almost 50 mAh/g at 100th cycle is also achieved. However, Li//Pani-LiPF6 with 20% conductor shows a remarkable performance of ~90 mAh/g at 100th cycle. This is feasible value for using as the positive electrode material of lithium ion secondary batteries. It is also proved that the powder type electrode of Pani is better to use than the film type one to improve the specific discharge capacity and its stability with cycle.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.22-32
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• 2008

Because of an emerging importance of clean energy, fuel cells are attract more attention due to their ability to produce high efficient power without any harmful emission. Fuel cells are energy conversion device with directly convert chemical energy into electrical energy by the chemical reactions, which have potential applications in automobile, spacecraft, stationary, industrial and home appliances. Recently there are gaining demand to develop an intermediate temperature fuel cell and available proton conductors at $200{\sim}500^{\circ}C$, which promising operating temperatures range for both material science and energy conversion processes. In this paper, we have reviewed electrochemical properties and current technology of solid state proton conductors. In addition, development of intermediate temperature fuel cell using the perovskite-type solid protonic conductor is also discussed.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.45-51
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• 2005

$K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ in the $K_2O-Li_2O-Al_2O_3$ ternary system was synthesized using aluminum nitrate solution as a starting material. For the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$, raw materials with chemical composition of $0.84K_2O{\cdot}0.082Li_2O{\cdot}5.2Al_2O_3$ were mixed in solution state. The effects of dispersant and solution-pH were investigated in minimizing the particle size and on the synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$. Ethanol was used for a dispersant, and $NH_4OH$ solution and nitric acid were added for pH adjustment. The solution pH was increased from 1.0 to 7.5 by 0.5 increments. Each sample was calcined at $1200^{\circ}C$ for 2 h and characterized with X-ray diffraction and particle size analyzer. The pH of solution significantly effected both particle size and phase formation, while the addition of ethanol only effected particle size. The synthesis of pure $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ was favored by addition of nitric acid (for pH control).

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.271-277
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• 2014

To overcome the limitations of the solid oxide fuel cells (SOFCs) due to the high temperature operation, there has been increasing interest in proton conducting fuel cells (PCFCs) for reduction of the operating temperature to the intermediate temperature range. In present work, the perovskite $BaCe_{0.85-x}Zr_xY_{0.15}O_{3-\delta}$ (BCZY, x = 0.1, 0.3, 0.5, and 0.7) were synthesized via solid state reaction (SSR) and adopted as an electrolyte materials for PCFCs. Powder characteristics were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer, Emmett and Teller (BET) surface area analysis. Single phase BCZY were obtained in all compositions, and chemical stability was improved with increasing Zr content. Anode-supported cell with $Ni-BaCe_{0.55}Z_{0.3}Y_{0.15}O_{3-\delta}$ (BCZY3) anode, BCZY3 electrolyte and BCZY3-$Ba_{0.5}Sr_{0.5}Co_{0.8}Fe_{0.2}O_{3-\delta}$ (BSCF) composite cathode was fabricated and electrochemically characterized. Open-circuit voltage (OCV) was 1.05 V, and peak power density of 370 ($mW/cm^2$) was achieved at $650^{\circ}C$.