RF 열플라즈마를 이용한 이차전지 음극재용 탄소나노실리콘복합소재 합성

이순직,김대신,연정미,박원규,신명선,최선용,주성후 한국재료학회 2023 한국재료학회지 Vol.33 No.6

To develop a high capacity lithium secondary battery, a new approach to anode material synthesis is required, capable of producing an anode that exceeds the energy density limit of a carbon-based anode. This research synthesized carbon nano silicon composites as an anode material for a secondary battery using the RF thermal plasma method, which is an ecofriendly dry synthesis method. Prior to material synthesis, a silicon raw material was mixed at 10, 20, 30, 40, and 50 wt% based on the carbon raw material in a powder form, and the temperature change inside the reaction field depending on the applied plasma power was calculated. Information about the materials in the synthesized carbon nano silicon composites were confirmed through XRD analysis, showing carbon (86.7~52.6 %), silicon (7.2~36.2 %), and silicon carbide (6.1~11.2 %). Through FE-SEM analysis, it was confirmed that the silicon bonded to carbon was distributed at sizes of 100 nm or less. The bonding shape of the silicon nano particles bonded to carbon was observed through TEM analysis. The initial electrochemical charging/ discharging test for the 40 wt% silicon mixture showed excellent electrical characteristics of 1,517 mAh/g (91.9 %) and an irreversible capacity of 133 mAh/g (8.1 %).

회전킬른반응기를 이용한 리튬이온전지용 Si/C/CNF 음극활물질의 제조 및 전기화학적 특성 조사

전도만,나병기,이영우 한국화학공학회 2018 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.56 No.6

Graphite is used as a sample anode active material. However, since the maximum theoretical capacity is limited to 372 mA h g-1, a new anode active material is required for the development of a high capacity lithium ion battery. The maximum theoretical capacity of Si is 4200 mA h g-1, which is higher than that of graphite. However, it is not suitable for direct application to the anode active material because it has a volume expansion of 400%. In order to minimize the decrease of the discharge capacity due to the volume expansion, the Si was pulverized by the dry method to reduce the mechanical stress and the volume change of the reaction phase, and the change of the volume was suppressed by coating the carbon layers to the particle size controlled Si particles. And carbon fiber is grown like a thread on the particle surface to control secondary volume expansion and improve electrical conductivity. The physical and chemical properties of the materials were measured by XRD, SEM and TEM, and their electrochemical properties were evaluated. In this study, we have investigated the synthesis method that can be used as anode active material by improving cycle characteristics of Si. 흑연은 리튬이온전지에 사용 되는 대표적인 음극활물질이다. 그러나 최대 이론 용량이 372 mA h g-1으로 제한되기 때문에 고용량의 리튬이온전지 개발을 위해서는 새로운 음극 소재 활물질이 필요하다. 실리콘의 최대 이론 용량은 4200 mA h g-1으로 흑연보다 높은 값을 나타내지만 부피 팽창이 400%로 크기 때문에 음극 소재 활물질로 바로 적용하기에는 적합하지 않다. 따라서 부피 팽창으로 인한 방전 용량의 감소를 최소화하기 위해 건식 방법으로 실리콘을 분쇄 하여 기계적 응력 및 반응상의 체적 변화를 감소시키고 입도 제어 된 실리콘 입자에 탄소를 코팅하여 체적의 변화를 억제하였다. 그리고탄소 섬유를 입자 표면에 실타래처럼 성장시켜 2차적으로 부피 팽창을 제어하고 전기전도성을 개선하였다. 실험 변수에따른 재료들의 물리화학적 특성을 XRD, SEM 및 TEM을 사용하여 측정하였고 전기화학적 특성을 평가 하였다. 본 연구에서는 실리콘의 수명 특성을 향상시켜 음극 소재 활물질로 사용 할 수 있는 합성 방법에 대하여 알아보았다.

Multiwalled nanotube-coated mesophase carbon microbeads for use as anode material in lithium ion batteries

양정진,박수길,최종환,김한주,Masayuki Morita 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

The recent developments in lithium ion secondary batteries (LIBs) have been achieved by using selected carbon materials as the anode. Mesophase carbon microbead (MCMB) anode materials have stable Li intercalation and de-intercalation characteristics, making them a good anode material for use in LIBs. However, batteries with pure MCMB anodes are known to have a low power density. Multiwalled carbon nanotubes (MWNTs) are one of the most promising materials for improving a range of electrochemical energy conversion and storage devices because of their unique physical properties, including high electrical conductivity and superior chemical and mechanical stability. Therefore, in this study, MWNTs were deposited on the surface of MCMB anodes to improve their electrical conductivity. The anode materials were separately functionalized using carboxylic acid and amine groups to form MWNT-COOH and MCMB-NH2, respectively, providing them with surfaces of opposite charge. The surface morphology was assessed using scanning electron microscopy, and the electrochemical characteristics were analyzed by cyclic voltammetry and AC impedance measurements in a coin cell. The AC impedance and cyclic voltammetry measurements indicated that MCMBs with MWNTs deposited on their surfaces are promising electrode materials, providing high power density for LIBs.

A Study on the Electrochemical Characteristics by Ag and Si02 Nano-Particle Additives on Si Anode Materials for Lithium lon Batteries

JeongUk LEE,SeokHwi HAN,HyeonSeok LEE 국제과학영재학회 2016 APEC Youth Scientist Journal Vol.8 No.1

In modern society, the core goal of multiple electronic devices is miniaturization and lightening. Therefore, built-in batteries have to be built with higher capacities in smaller spaces. Nowadays, researchers around the world are studying how to make secondary batteries that can be charged and discharged without replacement in order to improve their performance. The most promising research centers around lithium-ion battery technology. Anode materials such as Carbon and Silicon are currently used in lithium ion batteries and have drawn the attention offorward thinking scientists due to their high capacity properties. However, silicon has a volume problem during the charge-discharge process; Silicon can expand up to four times its original size and destroy the structure of the electrodes around it. Therefore, it currently cannot be commercialized. We created an anode electrode by coting Si powder with various materials. The substance used to make the anode electrode increased the conductivity of Ag and helped control the volume change by adding NP-SiO2 (SiO2nano-particles) and HF. We analyzed our sample with STEM (Scanning Transmission Electron Microscope), XPS (X-ray Photoelectron Spectroscopy), XRD (X-ray Diffraction) and made a coin cell with to confirm the electrochemical performance of the coin cell. As a result, our sample had higher rates of conductivity (better than existing Si anode materials) and made many charge/discharge cycles during the performance test.

MATERIAL RELIABILITY OF Ni ALLOY ELECTRODEPOSITION FOR STEAM GENERATOR TUBE REPAIR

Kim, Dong-Jin,Kim, Myong-Jin,Kim, Joung-Soo,Kim, Hong-Pyo Korean Nuclear Society 2007 Nuclear Engineering and Technology Vol.39 No.3

Due to the occasional occurrences of stress corrosion cracking(SCC) in steam generator tubing(Alloy 600), degraded tubes are removed from service by plugging or are repaired for re-use. Since electrodeposition inside a tube does not entail parent tube deformation, residual stress in the tube can be minimized. In this work, tube restoration via electrodeposition inside a steam generator tubing was performed after developing the following: an anode probe to be installed inside a tube, a degreasing condition to remove dirt and grease, an activation condition for surface oxide elimination, a tightly adhered strike layer forming condition between the electro forming layer and the Alloy 600 tube, and the condition for an electroforming layer. The reliability of the electrodeposited material, with a variation of material properties, was evaluated as a function of the electrodeposit position in the vertical direction of a tube using the developed anode. It has been noted that the variation of the material properties along the electrodeposit length was acceptable in a process margin. To improve the reliability of a material property, the causes of the variation occurrence were presumed, and an attempt to minimize the variation has been made. A Ni alloy electrodeposition process is suggested as a primary water stress corrosion cracking(PWSCC) mitigation method for various components, including steam generator tubes. The Ni alloy electrodeposit formed inside a tube by using the installed assembly shows proper material properties as well as an excellent SCC resistance.

Effect of operating temperature using Ni-Al-ZrH₂ anode in molten carbonate fuel cell

서동호(Seo, Dongho),장성철(Jang, Seongcheol),윤성필(Yoon, Sungpil),남석우(Nam, Suk Woo),오인환(Oh, In-Hwan),임태훈(Lim, Tae-Hoon),홍성안(Hong, Seong-Ahn),한종희(Han, Jonghee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06

Fuel cell is a device that directly converts chemical energy in the form of a fuel into electrical energy by way of an electrochemical reaction. In the anode for a high temperature fuel cell, nickel or nickel alloy has been used in consideration of the cost, oxidation catalystic ability of hydrogen which is used as fuel, electron conductivity, and high temperature stability in reducing atmosphere. Most MCFC stacks currently operate at an average temperature of 650?C. There is some gains with decreased temperature in MCFC to diminish the electrolyte loss from evaporation and the material corrosion, which could improve the MCFC life. However, operating temperature has a strong related on a number of electrode reaction rates and ohmic losses. Baker et al. reported the effect of temperature (575 to 650?C). The rates of cell voltage loss were 1.4mV/?C for a reduction in temperature from 650 to 600?C, and 2.16mV/?C for a decrease from 600 to 575?C. The two major contributors responsible for the change in cell voltage with reducing operation temperature are the ohmic polarization and electrode polarization. It appears that in the temperature range of 550 to 650?C, about 1/3 of the total change in cell voltage with decreasing temperature is due to an increase in ohmic polarization, and the electrode polarization at the anode and cathode. In addition, the oxidation reaction of hydrogen on an ordinary nickel alloy anode in MCFC is generally considered to take place in the three phase zone, but anyway the area contributing to this reaction is limited. Therefore, in order to maintain a high performance of the fuel cell, it is necessary to keep this reaction responsible area as wide as possible, that is, it is needed to keep the porosity and specific surface area of the anode at a high level. In this study effective anodes are prepared for low temperature MCFC capable of enhancing the cell performance by using zirconium hydride at least in part of anode material.

알루미늄 아노다이징 컬러표준화를 위한 컬러시편 개발 연구

이혜선 디자인융복합학회 2005 디자인융복합연구 Vol.4 No.1

알루미늄 표면처리업체의 국내외 현황을 전반적으로 모면 국내의 3D 업종기피와 더물어 중국의 저임금 구조를 바탕으로 국외 기업의 추격이 점차 심해지고 있는 실정이다. 따라서 국내 알루미늄 표면처리산업이 국제 경쟁력을 갖추려면 표준화 작업을 롱하여 산업의 구조적 생산성 향상이 필요하다. 생산성 향상을 위해서는 신기술의 개발도 중요하지만, 국내 알루미늄 표면처리업체 공장이 매우 영세한 관계로 현장작업 생산 시에 일어나는 각종 문제점들에 대한 정확한 파악과 그 원인 분석을 하여 개선함으로써 좋은 품질의 최종제품을 만들 수 있는 표준화의 확립이 매우 시급한 실정이다. 본 연구에서는 공정 표준화에 쓰일 1 차 컬러시편이 개발과 함께 실제 제품에 적용되는데 사용되어질 수 있도록 컬러 스펙트럼에 의한 컬러 추출이 아니라 트랜드의 분석을 통한 컬러를 추출하였다. 이를 위해 통신기기 및 고급 가전제품의 소재 및 컬러 트랜드를 분석하고 컬러예측 기관에서 제시된 트랜드 컬러와 2004 년 시판 되어진 제품의 컬러를 비교 분석하였다. 패션, 인테리어, 자동차 등 연관 분야의 컬러 트랜드와 그 변화 방향을 살펴보았다. 이를 토대로 1 차 50 가지의 컬러를 선정하였고 아노다이징 기술의 한계성과 실험 중 구현되는 컬러 바리에이선을 감안하여 26 가지를 선정하였다. Aluminum anodizing is one of the finish processes to apply aluminum as the products` finishing material. Products with aluminum finish gain premium value over many advantages that aluminum as genuine material already has. Increasing usage of aluminum, magnesium, and titanium is showing in various categories of products. Not only benefit of metallic material forces the move toward more uses of aluminum, but also user value products with genuine materials. Previous research shows that early adopter segment shows strong preference toward genuine materials especially with metallic finishes. However, situations in anodizing industries are not very competitive. They are lack of standardized process and are not prepared to communicate with designers who want to select appropriate colors for their products. Therefore, this research aimed to select color samples for aluminum anodizing that will use for standardization of anodizing process. First, general color trend and color trend of fashion, interior, and products were analyzed. Based on the analyses products that were introduced and sold in the market at 2004 were placed on the color spreading sheet and analyzed from different perspectives. Comparison of 2004 color trend analysis, 2006 color trend analysis, and colors from the market was carried out by color experts from different fields. Finally the study selected 26 colors for the first set of anodizing color samples to be developed.

Mo,Cu-doped CeO₂ as Anode Material of Solid Oxide Fuel Cells (SOFCs) using Syngas as Fuel

Diaz-Aburto, Isaac,Hidalgo, Jacqueline,Fuentes-Mendoza, Eliana,Gonzalez-Poggini, Sergio,Estay, Humberto,Colet-Lagrille, Melanie The Korean Electrochemical Society 2021 Journal of electrochemical science and technology Vol.12 No.2

Mo,Cu-doped CeO₂ (CMCuO) nanopowders were synthesized by the nitrate-fuel combustion method aiming to improve the electrical and electrochemical properties of its Mo-doped CeO₂ (CMO) parent by the addition of copper. An electrical conductivity of ca. 1.22·10^-2 S cm^-1 was measured in air at 800℃ for CMCuO, which is nearly 10 times higher than that reported for CMO. This increase was associated with the inclusion of copper into the crystal lattice of ceria and the presence of Cu and Cu₂O as secondary phases in the CMCuO structure, which also could explain the increase in the charge transfer activities of the CMCuO based anode for the hydrogen and carbon monoxide electro-oxidation processes compared to the CMO based anode. A maximum power density of ca. 120 mW cm^-2 was measured using a CMCuO based anode in a solid oxide fuel cell (SOFC) with YSZ electrolyte and LSM-YSZ cathode operating at 800℃ with humidified syngas as fuel, which is comparable to the power output reported for other SOFCs with anodes containing copper. An increase in the area specific resistance of the SOFC was observed after ca. 10 hours of operation under cycling open circuit voltage and polarization conditions, which was attributed to the anode delamination caused by the reduction of the Cu₂O secondary phase contained in its microstructure. Therefore, the addition of a more electroactive phase for hydrogen oxidation is suggested to confer long-term stability to the CMCuO based anode.

다양한 바이오매스 기반의 탄소 제조 및 리튬이온전지 음극활물질로의 응용

김찬교,제갈석,김하영,김지원,추연룡,심형섭,윤창민 유기성자원학회 2023 유기물자원화 Vol.31 No.3

본 연구에서는 여러 종류의 식물성 바이오매스 폐기물을 리튬이온전지용 음극활물질로 재활용하고자 하였다. 수거한 바이오매스는 세척 및 분쇄 후 질소 환경(850℃)으로 탄화하였으며, 이를 FE-SEM, EDS, FT-IR을 사용하여물리⋅화학적 특성을 비교하였다. 바이오매스 기반의 탄소 전구체로 왕겨, 밤껍질, 녹차 티백, 커피 폐기물을 사용했으며, 전구체의 성분에 따라 형태 및 탄소화 정도의 차이가 발생함을 확인하였다. 바이오매스 폐기물로 제조된탄소를 음극재로 활용하여 전기화학 성능을 비교한 결과 각각 65.8, 80.2, 90.6, 104.7mAh g-1의 방전용량을 나타내었으며, 커피 폐기물을 전구체로 제조한 탄소가 가장 높은 방전용량을 나타내었다. 이는 바이오매스의 원소 조성 및구성성분 차이로 인해 탄화 정도가 달라지기 때문이다. 최종적으로, 환경오염을 유발하는 다양한 식물성 바이오매스를 탄화를 통해 효과적인 에너지 저장매체로 활용할 수 있는 가능성을 제시하였다. In this study, various plant-based biomass are recycled into carbon materials to employ as anode materials for lithium-ion batteries. Firstly, various biomass of rice husk, chestnut, tea bag, and coffee ground are collected, washed, and ground. The carbonization process is followed under a nitrogen atmosphere at 850℃. The morphological and chemical properties of materials are investigated using FE-SEM, EDS, and FT-IR to compare the characteristic differences between various biomass. It is noticeable that biomass-derived carbon materials vary in shape and degree of carbonization depending on their precursor materials. These materials are applied as anode materials to measure the electrochemical performance. The specific capacities of rice husk-, chetnut-, tea bag-, and coffee ground-derived carbon materials are evaluated as 65.8, 80.2, 90.6, and 104.7 mAh g-1 at 0.2C. Notably, coffee ground-based carbon exhibited the highest specific capacity owing to the difference in elemental composition and the degree of carbonization. Conclusively, this study suggests the possibility of utilizing as energy storage devices by employing various plant-based biomass into active materials for anodes.

Enhancing Electrochemical Performance of Co(OH)₂ Anode Materials by Introducing Graphene for Next-Generation Li-ion Batteries

Kim, Hyunwoo,Kim, Dong In,Yoon, Won-Sub The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.3

To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH)₂-based anode materials to further improve electrochemical performance. The resultant Co(OH)₂/graphene composite exhibited a larger reversible capacity of ~1090 mAh g^-1, compared with ~705 mAh g^-1 for bare Co(OH)₂. Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH)₂ facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.