• Journal of Electrochemical Science and Technology
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• 제14권3호
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• pp.231-242
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• 2023

Li₂O-based cathodes utilizing oxide-peroxide conversion are innovative next-generation cathodes that have the potential to surpass the capacity of current commercial cathodes. However, these cathodes are exposed to severe cathode-electrolyte side reactions owing to the formation of highly reactive superoxides (O^x-, 1 ≤ x < 2) from O^2- ions in the Li₂O structure during charging. Succinonitrile (SN) has been used as a stabilizer at the cathode/electrolyte interface to mitigate cathode-electrolyte side reactions. SN forms a protective layer through decomposition during cycling, potentially reducing unwanted side reactions at the interface. In this study, a composite of Li₂O and Ni-embedded reduced graphene oxide (LNGO) was used as the Li₂O-based cathode. The addition of SN effectively thinned the interfacial layer formed during cycling. The presence of a N-derived layer resulting from the decomposition of SN was observed after cycling, potentially suppressing the formation of undesirable reaction products and the growth of the interfacial layer. The cell with the SN additive exhibited an enhanced electrochemical performance, including increased usable capacity and improved cyclic performance. The results confirm that incorporating the SN additive effectively stabilizes the cathode-electrolyte interface in Li₂O-based cathodes.

• 한국결정성장학회지
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• 제34권3호
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• pp.103-107
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• 2024

본 연구에서는 NCM [Li(Ni_xCo_yMn_z)O₂] 양극활물질을 합성하기 위한 내화갑의 재료로 순수 금속 재료인 Nickel을 제안하였다. Nickel은 산화에 강하고 녹는점이 높은 금속으로 알려져 있다. 니켈은 NCM 양극활물질의 주성분 중 하나로 양극물질 합성 동안에 saggar로 부터의 오염에 대한 문제에 자유로울 것으로 기대하였다. 본 연구진은 니켈이 NCM 양극물질 합성용 내화갑으로서의 가능성을 확인하고자 하였다. 900℃에서 Ni 금속 도가니와 Ni_0.8Co_0.1Mn_0.1(OH)₂ (NCM 811) 전구체 물질을 장시간 반응시켰을 때, 시간 변화에 따른 도가니 표면 반응층 변화를 분석하였다. 900℃에서 열처리 동안에 형성된 니켈 도가니 반응층은 니켈 산화물이었으며, 양극 전구체 산화물로 부터의 산소확산과 대기 중의 산소와 반응이 동시에 이루어져서 생성된 것으로 생각된다. 산화층은 480시간 이후로 그 두께의 변화가 느려지는 것으로 보아 전구체로 부터의 산소 확산속도가 감소되는 것으로 생각된다. 480시간까지는 도가니로 부터 탈락되지 않고 결합되어 있었다. 그러나 720시간 후에는 산화층이 탈락되는 것이 확인되어 일정 시간까지만 NCM 합성용 Saggar로서 사용 가능할 것으로 생각된다.

• 한국미생물·생명공학회지
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• 제39권4호
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• pp.382-386
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• 2011

이 연구에서는 일반적인 음극부 한 개에 양극부 한 개로 구성된 single-cathode 미생물연료전지(SCMFC)와 음극부 한 개에 양극부 두 개로 이루어진 dual-cathode 미생물연료전지(DCMFC)를 이용하여 전류발생에 비치는 영향을 확인하였다. 이 결과 dual-cathode 미생물연료전지에서 single-cathode 미생물연료전지 보다 전류발생이 약 40% 높았으며 COD 제거율도 약 13% 더 높은 것으로 확인되었다. 이것은 양극부와 음극부의 접촉면적이 증가하여 양극반응속도가 향상된 것에 의한 것으로 판단되며 dual-cathode 미생물연료전지가 single-cathode보다 전류발생과 COD제거 측면서 더 효율이 높은것으로 나타났다. 음극부 전자수용체에 대한 영향 실험에서는 전자수용체로 사용된 질산성질소의 농도가 높아질수록 급격히 전류발생이 감소하는 것을 확인 할 수 있었으며, 이에 대한 적절한 처리가 필요한 것으로 나타났다.

• 한국공작기계학회논문집
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• 제16권1호
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• pp.75-79
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• 2007

The cathode design is one of the most important parts in order to enhance the performance of fuel cells. A 3-D model of the porous oxygen reducing cathode with perforated current collectors is analysed for the enhanced design in fuel cells. Simulation is performed using equations of electric potential balance, momentum balance, and mass balance. The gas concentrations are quite large and are significantly affected by the reactions that take place. The weight fraction of oxygen, velocity field for the gas phase, and local overvoltage are illustrated in the porous reactive cathode layer. The current density is also analysed and the result shows the distribution and variation are stated in a wide range. It is found that the rate of reaction and the current production is higher beneath the orifice, and decreases as the distance to the gas inlet increases. The significance of the results is discussed in the viewpoint of the mass transportation phenomena, which is inferred that the mass transport of reactants dictates the efficiency of the electrode in this design and at these conditions.

• 한국전기전자재료학회논문지
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• 제11권1호
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• pp.18-25
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• 1998

G $d_{0.2}$C $e_{0.8}$ $O_{1.9}$(CGO) for electrolyte and L $a_{0.5}$S $r_{0.5}$Mn $O_3$(LSM50) for cathode in Solid Oxide Fuel Cells(SOFC) were synthesized by citrate process. Specimens were prepared with sintering temperatures at 110$0^{\circ}C$, 120$0^{\circ}C$ and 130$0^{\circ}C$, which were fabricated by slurry coating with citric acid contents. Interfacial resistance was measured between cathode and electrolyte using AC-impedance analyzer. With various citric acid content, the degree of agglomeration for the initial particles changed. Also sintering temperature changed the particle size and the degree of densification of cathode. Factors affecting the interfacial resistance were adherent degree of the electrolyte and cathode, distribution of TPB(three phase boundaries, TPB i.e., electrolyte/electrode/gas phase area) and porosity of cathode. By increasing the sintering temperature, particle size and densification of the cathode were increased. And then, TPB area which occurs catalytic reaction was reduced and so interfacial resistance was increased.sed.sed.d.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.424-425
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• 2005

The purpose of this study is to research and develop $LiFe_xMn_{1-x}PO_4$ cathode for lithium polymer batteries. $LiFe_xMn_{1-x}PO_4$ cathode active materials were prepared using a solid-state reaction by adding carbon black to the synthetic precursors. We investigated cyclic voltammetry and charge/discharge cycling of $LiFe_xMn_{1-x}PO_4$/SPE/Li cells. The discharge capacity of $LiFe_{0.5}Mn_{0.5}PO_4$ was l26mAh/g and 110mAh/g at 1st and 10th cycle.

• Korean Chemical Engineering Research
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• 제57권3호
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• pp.425-431
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• 2019

As rechargeable metal-air batteries will be ideal energy storage devices in the future, an active cathode electrocatalyst is required with bi-functionality on both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharge and charge, respectively. Here, a class of perovskite cathode catalyst with a micro-tubular structure has been developed by controlling bi-functionality from different Ru and Ni dopant ratios. A micro-tubular structure is achieved by the activated carbon fiber (ACF) templating method, which provides uniform size and shape. At the perovskite formula of $LaCrO_3$, the dual dopant system is successfully synthesized with a perfect incorporation into the single perovskite structure. The chemical oxidation states for each Ni and Ru also confirm the partial substitution to B-site of Cr without any changes in the major perovskite structure. From the electrochemical measurements, the micro-tubular feature reveals much more efficient catalytic activity on ORR and OER, comparing to the grain catalyst with same perovskite composition. By changing the Ru and Ni ratio, the $LaCr_{0.8}Ru_{0.1}Ni_{0.1}O_3$ micro-tubular catalyst exhibits great bi-functionality, especially on ORR, with low metal loading, which is comparable to the commercial catalyst of Pt and Ir. This advanced catalytic property on the micro-tubular structure and Ru/Ni synergy effect at the perovskite material may provide a new direction for the next-generation cathode catalyst in metal-air battery system.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.326-329
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• 2005

Proton exchange membrane (PEM) should be sufficiently hydrated with proper water management to maintain a good ionic conductivity and performance of a PEM fuel cell. However. cathode flooding resulting from excess water can impede the transport of reactants and hence deteriorate the fuel cell performance. For the PEM fuel cell to be commercially viable as vehicle or portable applications, the flooding on the cathode side should be minimized during the fuel cell operation. In this study, visualization technique was applied to understand the cathode flooding phenomena on the cathode side of a PEM fuel cell. To this end. a transparent PEM unit fuel cell wi th an act ive area of $25cm^2$ was designed and manufactured to allow for the visualization of cathode channel with performance characteristics. Two-phase flow resulting from the electro-chemical reaction of fuel cell was investigated experimentally. The images photographed by CCD camera with cell operating temperatures $(30\~50^{\circ}C)$ were presented. Results indicated that the flooding on the cathode side first occurs near the exit of cathode channel. As the operating temperature of fuel cell increases. it was found that liquid water droplets tend to evaporate easily and it can have an influence on lowering the flooding level. It is expected that this study can effectively contribute to the detailed researches on modeling water transport of an operating PEM fuel cell including two-phase flow phenomena.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.195-201
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• 2018

To enhance the performance of cathodes at low temperatures, a Cu-coated cathode is prepared, and its electrochemical performance is examined by testing its use in a single cell. At $620^{\circ}C$ and a current density of $150mAcm^{-2}$, a single cell containing the Cu-coated cathode has a significantly higher voltage (0.87 V) during the initial operation than does that with an uncoated cathode (0.79 V). According to EIS analysis, the high voltage of the cell with the Cu-coated cathode is due to the dramatic decrease in the high-frequency resistance related to electrochemical reactions. From XPS analysis, it is confirmed that the Cu is initially in the form of $Cu_2O$ and is converted into CuO after 150 h of operation, without any change in the state of the Ni or Li. Therefore, the high initial cell voltage is confirmed to be due to $Cu_2O$. Because $Cu_2O$ is catalytically active toward $O_2$ adsorption and dissociation, $Cu_2O$ on a NiO cathode enhances cell performance and reduces cathode polarization. However, the cell with the Cu-coated cathode does not maintain its high voltage because $Cu_2O$ is oxidized to CuO, which demonstrates similar catalytic activity toward $O_2$ as NiO.

• 한국전기전자재료학회논문지
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• 제11권11호
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• pp.1049-1054
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• 1998

The LiCo$O_2$ powder was synthesized by a solution phase reaction. This shows a high (003) peak intensity and low (104) or (101) peak intensities in X-ray diffraction spectra. The LiCo$O_2$/Li cell shows an initial discharge capacity of 102.9mAh/g and an average discharge potential or 3.877V at a current density of 50mA/g between 3.0~4.2V. The peaks of dQ/dV plot are associated with Li ion intercalation/deintercalation reaction. To evaluate the cycleability of an actual battery system, cylindrical lithium ion cell was manufactured using graphitized MPCF anode and LiCoO$_2$ cathode. After 100th cycle, this cel maintains 80% capacity of 10th cycle value. The LiCoO$_2$/MPCF cell has a high discharge voltage of 3.6~3.7V and a good cycle life performance on cycling between 4.2~2.7V.