• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.142-149
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• 2005

[ $LiNiO_2$ ] was mixed with $TiO_2$ or ZnO for the preparation of a cathode. The electrochemical properties of the cathode were investigated and the effects of the addition of $TiO_2$ or ZnO were discussed. The first discharge capacity decreased as the quantity of the added $TiO_2$ or ZnO increased. It is probably due to the decrease in the area of reaction interface according to the increase in the amount of the added oxide. When 2wt.% and 5wt.% of oxides are added, the discharge capacity increased as the number of cycles increased. It is considered that this results from the increase in the area of reaction interface because the oxide is detached from the $LiNiO_2$ with the increase in the number of cycles. The 1wt.% $TiO_2$ or ZnO-added $LiNiO_2$ had a larger first charge capacity than $LiNiO_2$. This is considered to result from the deintercalation of Li ions in the Ni sites along with the Li ions in the Li sites.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.383-390
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• 2001

We have investigated the L $i_{1+x}$M $n_2$ $O_4$system as a cathode material for lithium rechargeable batteries. To improve the cycle performance of spinel LiM $n_2$ $O_4$ as the cathode of 4V class lithium secondary batteries, spinel phase L $i_{1+x}$M $n_2$ $O_4$(x=0, 0.025, 0.05, 0.075) was prepared at 75$0^{\circ}C$ for 48h. The preparation of L $i_{1+x}$M $n_2$ $O_4$ from L $i_2$ $O_3$ and Mn $O_2$ under air is studied. The compounds were synthesized by using solid-state reaction. Structural refinements were carried out with a Rietveld-refinement program. Electrochemical properties were examined using the Li/L $i_{1+x}$M $n_2$ $O_4$ cells. The capacity of L $i_{1+x}$M $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ decreases with increases lithium content, while the cycle life improves. The initial discharge capacity are 118mAh/g and 116mAh/g for LiM $n_2$ $O_4$ and L $i_{1.025}$M $n_2$ $O_4$, respectively.pectively.

• 전기화학회지
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• 제3권4호
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• pp.191-195
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• 2000

교류 임피던스법을 사용하여 온도, 부하전위 및 전극내 테프론 함량에 따른 인산형 연료전지의 산소전극 반응의 특성을 연구하였다. $105wt.\%$ 인산에서 산소 전극의 임피던스 거동은 전극 계면 저항, 전극 계면 캐패스턴스 및 전해질 저항으로 이루어진 간단히 회로로 특징지어지고, 이것으로부터 구한 인산의 전기전도도는 $130\~190^{\circ}C$의 온도범위에서 0.31-0.47 S/cm 로 나타났다. 부하전위와 온도가 증가함에 따라 산소극의 계면저항은 감소하였으나 산소극의 계면 캐패스턴스는 증가하였으며, 이것은 산소극의 반응속도와 전극의 계면 임피던스가 직접적인 관계를 가진다는 것을 의미한다. 테프론 함량에 따른 인산형 연료전지 단전지의 성능을 조사하여 임피던스 측정결과와 비교하였으며, $40wt.\%$에서 최대 성능을 나타내었고, 이것은 산소극의 계면 임피던스 값이 최적 상태를 나타내었기 때문인 것으로 판단되며, 이러한 결과들이 전극의 3상계면 상태와 연관지어 토의되었다.

• 한국세라믹학회지
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• 제44권6호
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• pp.297-302
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• 2007

With aids of square wave voltammetry (SWV) the redox behavior for various combination of polyvalent ions (Sb+Fe, Sb+Zn, Sb+Ce+Ti+Zn) was investigated in alkali-alkaline earth-silica CRT (Cathode Ray Tube) glass melts. The current-potential curve so called voltammogram was produced at temperature range of 1400 to $1000^{\circ}C$ under the scanned potential between 0 and -800 mV at 100 Hz. In the case of the Sb+Fe and Sb+Zn doped melts, peak for $Sb^{3+}/Sb^0$ shown voltammogram was shifted to negative direction comparing to the only Sb doped melts. However, according to voltammogram of Sb+Ce+Ti+Zn doped melt, Ti and Ce except Zn had hardly any influence on the redox reaction of Sb. Based on the temperature dependence of the peak potential, standard enthalpy (${\Delta}H^0$) and standard entropy (${\Delta}S^0$) for the reduction of $Fe^{3+}$ to $Fe^{2+}$, $Sb^{3+}$ to $Sb^0$, $Zn^{2+}$ to $Zn^0$ and $Ti^{2+}$ to $Ti^0$ in each polyvalent ion combination of CRT glass melts were calculated.

• 한국세라믹학회지
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• 제56권5호
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• pp.497-505
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• 2019

Lanthanum-based transition metal cations containing perovskites have emerged as potential catalysts for the intermediate-temperature (600-800℃) oxygen reduction reaction (ORR). Here, we report a facile acetylacetone-assisted combustion route for the synthesis of nanostructured La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF6428) cathodes for intermediate-temperature solid-oxide fuel cells (IT-SOFCs). The as-prepared powder was analyzed by thermogravimetry analysis-differential scanning calorimetry. The powder calcined at 800℃ was characterized by X-ray diffraction, scanning electrode microscopy, energy dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area measurements. It was found that the porosity of the air electrode significantly increased by utilizing the nanostructured LSCF6428 instead of commercial powder. The performance of a single cell fabricated with the nanostructured LSCF6428 cathode increased by 112%, from 0.4 to 0.85 W cm^-2, at 700℃. Electrochemical impedance spectroscopy showed a considerable reduction in the area-specific resistance and activation energy from 133.5 to 61.5 kJ/mol, resulting in enhanced electrocatalytic activity toward ORR and overall cell performance.

• 한국결정성장학회지
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• 제32권2호
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• pp.61-67
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• 2022

폐리튬이차전지 스크랩으로부터 회수한 유가금속인 니켈, 코발트, 망간을 정제하여 제조한 리튬이차전지 전구체 금속염 용액으로 테일러반응을 통해 NCM 811 전구체를 제조하였다. 반응 시간에 따른 전구체 형태 변화를 SEM, PSA, ICP 분석 결과를 기반으로 합성 조건을 확립하였다. 이에 상업용 전구체와 재활용하여 합성한 전구체의 전기 화학적 특성인 충·방전 특성, 율특성, 수명특성 등을 평가하여 비교 연구하였으며, 상업용 전구체와 비교 시 큰 차이가 없거나 일부 특성에서는 우수한 특성을 확인할 수 있었다.

• 자원리싸이클링
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• 제33권1호
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• pp.15-21
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• 2024

전기차용 리튬이온배터리의 수요가 증가함에 따라 향후 발생할 폐리튬이온배터리 중의 유가금속 회수가 필요하다. 본 연구에서는 리튬이온배터리의 NCM계 양극재를 수소환원과 수침출에 의해 리튬을 수산화리튬으로 회수할 때의 회수율에 미치는 반응온도의 영향을 조사하였다. 반응온도가 상승함에 따라 수소에 의한 NiO, CoO의 환원에 의해 무게 감소율이 반응초기부터 급격하게 증가하였으며 동시에 H₂O 발생량도 증가하였다. 602 ℃ 이상에서는 양극재 중의 Ni, Co가 전부 환원되어 금속상으로 존재하였다. 그리고 수소환원 온도의 상승과 함께 Li 회수률도 증가하였으나 704 ℃ 이상에서는 약 92 % 이상의 유사한 수준을 나타내었다. 따라서 폐Li이온 배터리의 전처리로 수소환원하는 것에 의해 리튬만 사전에 회수하고 잔사를 재처리하면 효율적으로 유가금속을 분리하여 회수할 수 있을 것으로 기대된다.

• 에너지공학
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• 제19권2호
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• pp.73-80
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• 2010

고체산화물연료전지(SOFC)는 청정에너지기술로써 화학에너지를 전기에너지로 직접 전환한다. SOFC는 열병합발전과 결합하여 80%이상의 효율을 올릴 수 있으며 천연가스와 바이오가스 등 연료에 대한 융통성이 폴리머전해질막연료전지(PEMFC)보다 높다. YSZ전해질과 함께 SOFC에 주로 채용되는 공기극 재료는 아직까지 Sr이 첨가된 $LaMnO_3$(LSM)이다. LSM 이외에, 혼합전도성을 가지는 페로브스카이트로서 Sr첨가 $LaCoO_3$(LSCo), $LaFeO_3$(LSF), $LaFe_{0.8}Co_{0.2}O_3$(LSCF)는 공기극 임피던스가 LSM에 비해 현저히 낮아 연구가 증가하고 있다. 그러나 SOFC전극의 소결온도에서 YSZ과 고체반응을 일으키는 문제점과 열팽창 계수가 YSZ와 격차가 크게 나는 문제점 때문에 전극 제조가 복잡하다. 따라서 전해질과의 화학적 안정성 및 유사한 열팽창계수(TEC)를 가지면서 우수한 전기화학활성을 제공하는 것이 해결해야할 중요한 문제로 남는다.

• 한국세라믹학회지
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• 제42권6호
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• pp.425-431
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• 2005

Line Shaped Solid Oxide Fuel Cell (SOFC) with multilayered structure has been fabricated via direct-writing process. The cell is electrolyte of Ni-YSZ cermet anode, YSZ electrolyte and LSM cathode. They were processed into pastes for the direct writing process. Syringe filled with each electrode and electrolyte paste was loaded into the computer-controlled robe-dispensing machine and the paste was dispensed through cylindrical nozzle of 0.21 mm in diameter under the air pressure of 0.1 tow onto a moving plate with 1.22 mm/s. First of all, the anode paste was dispensed on the PSZ porous substrate, and then the electrolyte paste was dispensed. The anode/electrolyte and the PSZ substrate were co-fired at $1350^{\circ}C$ in air atmosphere for 3 h. The cathode layer was similarly dispensed and sintered at $1200^{\circ}C$ for 1 h. All the electrode/electrolyte lines were visually aligned during the direct writing process. The effective reaction area of fabricated SOFC was $0.03 cm^2$, and the thickness of anode, electrolyte and cathode was 20 $\mu$m, 15 $\mu$m, and 10 $\mu$m, respectively. The single line-shaped SOFC fabricated by direct-writing process exhibited OCV of 0.95 V and maximum power density of $0.35W/cm^2$ at $810^{\circ}C$.

• 한국세라믹학회지
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• 제43권2호
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• pp.121-125
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• 2006

[ $LiFePO_4$ ] is one of the promising materials for cathode material of secondary lithium batteries due to its high energy density, low cost, environmental friendliness and safety. $LiFePO_4$ was synthesized by the solid-state reaction method at 500 - 800°C. The crystal structure of $LiFePO_4$ was analyzed by X-ray powder diffraction. The samples synthesized at 600 and $700^{\circ}C$ showed a single phase of a olivine structure. The particle sizes were increased and the specific surface areas were decreased with heating temperatures. The electrochemical performance was investigated by coin cell test. The discharge capacities at 0.1 C-rate were 118 mAh/g and 112 mAh/g at $600^{\circ}C,\;700^{\circ}C$, respectively. In an attempt to improve the electrical conductivity of cathode materials, $LiFePO_4/graphite$ composite was prepared with various graphite contents. The electrical conductivity and discharge capacity were increased with increasing the graphite contents in composite samples. The rate capabilities at high current densities were also improved.