• 한국세라믹학회지
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• 제36권2호
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• pp.172-177
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• 1999

흑연 및 카본재료는 알칼리 금속을 intercalation/de-intercalation 시킬수 있는 특성을 지니고 있으며, 또한 Li-intercalated carbon의 화학 potential이 Li 금속에 가까운 낮은 값을 지닌 특성으로 리튬 이차전지의 anode 전극재료로서 널리 쓰일 가능성이 매우 크다. 본 연구에서는 카본재료 중 mesocarbon microbeads (MCMB)를 리튬 이차전지의 anode 전극재료로 사용하여 전지반응을 수행하고, 전극의 충.방 전 특성과 전극계면 반응특성에 대하여 연구하였다. 즉, Li/carbon(MCMB) 전지 cell를 제작하고 전해질과 전극계면에서 일어나는 전기화학 반응특성을 충.방 전 시험, Potentionat/Galvanostat 시험, FT-IR 분석, XRD 및 SED 분석에 의하여 고찰하였다. 전지반응이 진행되면서 전극과 전해질 계면에서 고체상태의 부동태 막 (passivation film)이 형성되었으며, 일단 형성된 막은 전해질 내에 용해되지 않고 충.방 전 횟수가 증가하면서 두께가 증가되었다. 또한, 이러한 전극 계면에서 형성된 부동태 막과 중전용량과의 관계에 대하여 고찰하였다.

• 한국산학기술학회논문지
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• 제16권8호
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• pp.5728-5735
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• 2015

단일챔버 미생물연료전지에 분리막으로 세라믹막과 나피온막을 적용하여 전기발생특성을 분석함으로써 세라믹막의 적용가능성을 구명하고자 하였다. 또한 환원전극으로서 백금촉매가 도포된 탄소천과 일반 탄소천을 사용하여 백금촉매 효과 및 전기발생특성을 비교하였다. 회분식 실험에서 전기발생특성이 가장 안정적인 것은 acetate를 기질로 사용하였을 때였다. Formate는 전기발생특성이 acetate보다 다소 높았으나 불안정하였고 propionate와 butyrate는 acetate에 비하여 전기발생량이 상대적으로 낮았다. 환원전극으로서 백금촉매가 도포되어 있는 탄소천과 일반 탄소천을 비교한 결과 백금촉매가 도포된 탄소천의 전력발생량이 일반 탄소천에 비하여 1.2배 높게 나타났지만 약 5배 정도 비용 차이가 있음을 고려하면 미생물연료전지의 적용에 있어 효율성과 경제성은 함께 고려되어야 할 것으로 판단된다. 분리막으로서 세라믹막과 나피온막을 적용한 미생물 연료전지에서 발생한 평균 전압은 합성폐수를 이용한 실험에서 각각 $523.67mV{\pm}49.41mV$, $424.09mV{\pm}79.95mV$이었다. 미생물연료전지에 분리막으로 세라믹막과 나피온막을 적용하여 전력발생 및 유기물제거효율을 비교한 결과, 세라믹막이 나피온막의 대안이 될 수 있음을 확인하였다.

• 한국세라믹학회지
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• 제55권5호
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• pp.407-418
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• 2018

Increasing demand for portable and wireless electronic devices with high power and energy densities has inspired global research to investigate, in lieu of scarce rare-earth and expensive ruthenium oxide-like materials, abundant, cheap, easily producible, and chemically stable electrode materials. Several potential electrode materials, including carbon-based materials, metal oxides, metal chalcogenides, layered metal double hydroxides, metal nitrides, metal phosphides, and metal chlorides with above requirements, have been effectively and efficiently applied in electrochemical supercapacitor energy storage devices. The synthesis of self-grown, or in-situ, nanostructured electrode materials using chemical processes is well-known, wherein the base material itself produces the required phase of the product with a unique morphology, high surface area, and moderate electrical conductivity. This comprehensive review provides in-depth information on the use of self-grown electrode materials of different morphologies in electrochemical supercapacitor applications. The present limitations and future prospects, from an industrial application perspectives, of self-grown electrode materials in enhancing energy storage capacity are briefly elaborated.

• 한국세라믹학회지
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• 제53권3호
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• pp.376-380
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• 2016

A composite electrode made of iron oxide nanoparticles/multi-wall carbon nanotube (iNPs/M) delivers high specific capacity and cycle durability. At a rate of $200mAg^{-1}$, the electrode shows a high discharge capacity of ${\sim}664mAhg^{-1}$ after 100 cycles, which is ~ 70% of the theoretical capacity of $Fe_3O_4$. Carbon black, carbon nanotube, and graphene as anode materials have been explored to improve the electrical conductivity and cycle stability in Li ion batteries. Herein, iron oxide nanoparticles on acid treated MWCNTs as a conductive platform are combined to enhance the drawbacks of $Fe_3O_4$ such as low electrical conductivity and volume expansion during the alloying/dealloying process. Enhanced performance was achieved due to a synergistic effect between electrically 3D networks of conductive MWCNTs and the high Li ion storage ability of $Fe_3O_4$ nanoparticles (iNPs).

• 한국세라믹학회지
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• 제30권10호
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• pp.819-822
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• 1993

The purpose of this paper is a investigation of sensing mechanism for the carbon monoxide gas in CuO infiltrated ZnO ceramics. Potential barriers between CuO and ZnO can explain the selective sensing of carbon monoxide gas in the physically contacted CuO/ZnO ceramics. A specimen having no potential barrier between CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO and ZnO was prepared to see whether the gas sensing mechanism is related to the potential barrier. CuO was painted on the non electrode sides of ZnO ceramics. The CuO painted ZnO ceramics showed that the sensitivityfor the carbon moxnoxide gas was 1.3 times as high as that for the hydrogen gas. It is almost same gas sensitivity as that of the CuO infiltrated ZnO ceramics.

• Journal of Ceramic Processing Research
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• 제19권6호
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• pp.499-503
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• 2018

In this paper, cobalt embedded in nitrogen and sulfur co-doped carbon nanotubes (CoNSTs) were synthesized for oxygen reduction reaction (ORR) catalysts. The CoNSTs were prepared through a facile heat treatment method without any templates. Different amounts of the metal salt were employed to examine the physicochemical and electrochemical properties of the CoNSTs. The CoNSTs showed the bamboo-like tube morphology with the encased Co nanoparticles in the tubes. Through the x-ray photoelectron spectroscopy analysis, the catalysts exhibited different chemical states of the nitrogen and sulfur species. As a result, the CoNST performed high activity toward the ORR in an acidic condition with the onset potential of 0.863 V (vs. reversible hydrogen electrode). It was clearly demonstrated from the electrochemical characterizations that the quality of the nitrogen and sulfur species significantly influences the ORR activity rather than the total amount of the dopants.

• 한국세라믹학회지
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• 제47권1호
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• pp.92-96
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• 2010

Based on the differential electrode equilibria approach, potentiometric YSZ sensors with semiconducting oxide electrodes for CO detection are developed. To improve the selectivity, sensitivity and response-time of the sensor, our strategy includes (a) selection of an oxide with a semiconducting response to CO, (b) addition of other semiconducting materials, (c) addition of a catalyst (Pd), (d) utilization of combined p- and n-type electrodes in one sensor configuration, and (e) optimization of operating temperatures. Excellent sensing performance is obtained by a novel device structure incorporating $La_2CuO_4$ electrodes on one side and $TiO_2$-based electrodes on opposite substrate faces with Pt contacts. The resulting response produces additive effects for the individual $La_2CuO_4$ and $TiO_2$-based electrodes voltages, thereby realizing an even higher CO sensitivity. The device also is highly selective to CO versus NO with minor sensitivity for NO concentration, compared to a notably large CO sensitivity.

• 한국세라믹학회지
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• 제55권1호
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• pp.50-54
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• 2018

This study investigated the long-term durability of catalyst(Pd or Fe)-infiltrated solid oxide cells for $CO_2$/steam co-electrolysis. Fuel-electrode supported solid oxide cells with dimensions of $5{\times}5cm^2$ were fabricated, and palladium or iron was subsequently introduced via wet infiltration (as a form of PdO or FeO solution). The metallic catalysts were employed in the fuel-electrode to promote $CO_2$ reduction via reverse water gas shift reactions. The metal-precursor particles were well-dispersed on the fuel-electrode substrate, which formed a bimetallic alloy with Ni embedded on the substrate during high-temperature reduction processes. These planar cells were tested using a mixture of $H_2O$ and $CO_2$ to measure the electrochemical and gas-production stabilities during 350 h of co-electrolysis operations. The results confirmed that compared to the Fe-infiltrated cell, the Pd-infiltrated cell had higher stabilities for both electrochemical reactions and gas-production given its resistance to carbon deposition.

• Journal of Ceramic Processing Research
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• 제19권5호
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• pp.413-418
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• 2018

All-solid-state lithium batteries (ASSBs) using inorganic sulfide-based solid electrolytes are considered prospective alternatives to existing liquid electrolyte-based batteries owing to benefits such as non-flammability. However, it is difficult to form a favorable solid-solid interface among electrode constituents because all the constituents are solid particles. It is important to form an effective electron conduction network in composite cathode while increasing utilization of active materials and not blocking the lithium ion path, resulting in excellent cell performance. In this study, a mixture of fibrous VGCF and spherical nano-sized Super P was used to improve rate performance by fabricating valid conduction paths in composite cathodes. Then, composite cathodes of ASSBs containing 70% and 80% active materials ($LiNi_{0.6}Co_{0.2}Mn_{0.2}O_2$) were prepared by a solution-based process to achieve uniform dispersion of the electrode components in the slurry. We investigated the influence of binary carbon additives in the cathode of all-solid-state batteries to improve rate performance by constructing an effective electron conduction network.

• 한국기계가공학회지
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• 제13권6호
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• pp.119-126
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• 2014

Micro-holes of conductive ceramic are required in micro structures. Micro-electrical discharge machining (Micro-EDM) is an effective machining method since EDM is as process for shaping hard metals and complex-shaped holes by spark erosion in all kinds of electro-conductive materials. However, as the depth of micro hole increases, the machining condition becomes more unstable due to inefficient removal of debris between the electrode and the workpiece. In this paper, micro-EDM was performed to evaluate machining characteristic such as electrode wear, machining time, taper angle, radial clearance with varying voltage and ultrasonic vibration on 10 vol.% Carbon-nanotube reinforced conductive $Al_2O_3$ composite fabricated by spark plasma sintering in previous research.