3D flexible Si based-composite (Si@Si₃N₄)/CNF electrode with enhanced cyclability and high rate capability for lithium-ion batteries

Kim, Si-Jin,Kim, Min-Cheol,Han, Sang-Beom,Lee, Gyu-Ho,Choe, Hui-Seon,Kwak, Da-Hee,Choi, Sun-Yong,Son, Byung-Goo,Shin, Myoung-Sun,Park, Kyung-Won Elsevier 2016 Nano energy Vol.27 No.-

<P><B>Abstract</B></P> <P>Despite extremely high capacity of Si-based anodes in lithium-ion batteries (LIB), Si-based materials have shown a structural collapse caused by a volumetric expansion/contraction during the cycling process. The conventional electrode structure, which consists of active materials, a current collector, a conducting agent, and a binder, actually showed a low loading of active material due to the other heavy components. In this study, we prepared a 3D flexible Si-composite electrode consisting of core (Si)-shell (Si<SUB>3</SUB>N<SUB>4</SUB>) NPs (Si@Si<SUB>3</SUB>N<SUB>4</SUB>) and carbon nanofibers (denoted as Si-composite/CNF). The Si-composite/CNF was directly utilized as an anode in the absence of the other components was electrochemically evaluated using a coin-type cell. The Si-composite/CNF showed a high capacity of 665mAhg<SUP>−1</SUP> at a fairly high current density of 10Ag<SUP>−1</SUP> and an extremely low capacity loss for 2000 cycles.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We prepared Si-composite/CNF exhibits a 3D flexible Si-composite electrode. </LI> <LI> The electrode consists of core (Si)-shell (Si<SUB>3</SUB>N<SUB>4</SUB>) NPs (Si@Si<SUB>3</SUB>N<SUB>4</SUB>) and carbon nanofibers. </LI> <LI> The Si-composite/CNF was directly utilized as an anode. </LI> <LI> Si-composite /CNF exhibited high specific capacity and improved high rate cycling performance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Microstructure and Tensile Properties in Low Pressure Cast Al-Si Alloy through Cooling Rate Control

Suh, Jun-Young,Park, Sung Jin,Lee, Hee-Kwon,Chang, Si Young Materials Research Society of Korea 2020 한국재료학회지 Vol.30 No.2

In this study, three kinds of metal chills such as SS400, AC4CH and brass, with different thicknesses of 40 ~ 80 mm, were applied for low pressure casting of Al-Si alloy to control cooling rate. The microstructural characteristics with increasing cooling rate were represented using factors including D₁, D₂, size of primary α phases and shape factor and size of eutectic Si. The tensile properties were investigated and additionally analyzed based on the microstructural characteristics. As the cooling rate increased, D₁, D₂, and sizes of primary α phases and eutectic Si apparently decreased and the shape factor of eutectic Si increased to over 0.8. The ultimate tensile strength (UTS) and yield strength (YS) increased with decreasing D₁, D₂, and size of primary α phases, while elongation increased with decreasing size of eutectic Si and concurrently increasing shape factor of eutectic Si. This indicated that the primary α phases and eutectic Si in Al-Si alloy were refined with increasing cooling rate, resulting in improvement of UTS and YS without sacrificing elongation. After the tensile test, preferential deformation of primary α phases was observed in the Al-Si alloy produced at higher cooling rates of more than 0.1 K/s.

Controlled infiltration profile of SiC coating layer on graphite by Si vapor deposition reaction

Kuk-Jin Hwang,Si-Young Bae,Kyoung-Ho Kim,Yoon-Cheol Lee,Jung-Tae Hwang,Heesoo Lee,Seong Min Jeong,Myung-Hyun Lee 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.2

SiC-coated graphite was successfully fabricated at different temperatures (1300-1600 oC) through a silicon vapor depositionreaction (Si-VDR) process. Si powder was used for the Si source of the SiC coating layers. When Si powder was evaporatedat high temperature near the melting point of bulk Si, Si gases are moved and changed into Si liquid at the surface of thegraphite. The high-temperature process facilitated the formation of SiC coating layers on the graphite. The microstructural,mechanical, and thermal oxidation properties of the coated graphite were investigated.

SiC 단결정의 TSSG 공정을 위한 전이금속 특성 연구

이승준,유용재,정성민,배시영,이원재,신윤지,Lee, Seung-June,Yoo, Yong-Jae,Jeong, Seong-Min,Bae, Si-Young,Lee, Won-Jae,Shin, Yun-Ji 한국결정성장학회 2022 한국결정성장학회지 Vol.32 No.2

본 연구에서는 SiC 단결정의 TSSG 공정중 결정 품질을 저하시키지 않으면서도 의도하지 않은 질소 도핑(N-UID)을 쉽게 제어하기 위해 지금까지 Co 또는 Sc 전이금속을 첨가한 신규 용융조성을 제안한다. Co 또는 Sc의 특성을 파악하기 위해 Ar 분위기에서 1900℃ 온도에서 약 2시간 동안 열처리 실험을 수행했다. 용융조성은 Si-Ti 10 at% 또는 Si-Cr 30 at%를 비롯하여, 탄소 용해도에 효과적이라고 알려진 Co 또는 Sc을 각각 3 at% 첨가하였다. 열처리 후 도가니 단면을 가공하여 도가니-용융물 계면에서 발생한 Si-C 반응층을 관찰하고, 탄소황분석을 통해 조성에 따른 탄소 용해도를 간접적으로 분석하였다. 그 결과, Si-Sc 기반 용융조성이 TSSG 공정에 적합한 특성을 갖는 Si-C반응층을 형성하고 있었다. 또한 탄소황분석 결과에서도 Cr 다음으로 높은 탄소량이 갖는 것으로 분석되었다. Sc는 Cr에 비해 질소와의 반응성이 낮은 이점을 가지므로 TSSG 공정에 Si-Sc 용융조성을 적용하면, 본 연구에서 의도한 대로 SiC 단결정 성장속도와 질소 UID를 모두 제어할 수 있는 것으로 고려된다.

Wire Saw 슬러리로부터 Si, SiC 분리 및 제올라이트 합성에 대한 연구

한승열,이종대,박노국,이태진,류시옥 한국공업화학회 2004 응용화학 Vol.8 No.1

This study was focused on the separation of Si and from Wire Saw Slurry in Wire Saw Slicing process and synthesis of zeolite by mixing with water glass obtained from its process and Alumina. In order to separate Si and SiC from Wire Saw Slurry, Alkai disslution was used and then Na₂O showed superior dissoluble property of Si. At this time, SiC was separated as powder from Alkali apueous solution. Si was dissolved as a liquid in Alkali aqueous solution. After removing SiC powder, the powder formed was obtained from drying. Alkali aqueous solution and then it was the water glass (Na₂SiO₃)confirmed by XRD analysis. Water glass (Na₂SiO₃) and Alumina mixed with pure water made as a synthesis of zeolite through the crystallization by aging and hydrothermal reaction. The manufactured zeolite was Sodium Aluminum Silicate Hydrate confirmed by XRD analysis.

Wire Saw 슬러리로부터 Si와 SiC의 선택적 회수

한승열,이종대,전진혁,박노국,이태진,류시옥 嶺南大學校 工業技術硏究所 2004 工業技術硏究所論文集 Vol.32 No.1

This study was focused on the recovery of Si and SiC from wire saw slurry in wire saw slicing process. In order to separate Si and SiC from wire saw slurry, alkali dissolution method was used and then Na₂O showed superior dissolution property of Si. At this time, SiC was separated as powder from alkali aqueous solution. Si was dissolved as a liquid in alkali aqueous solution. After removing SiC powder, the powder was obtained by drying alkali aqueous solution and then it's XRD analysis showed that it was the water glass (Na₂SiO₃).

적외선 분광법에 의한 양이온 교환된 Faujasite 의 T - O 결합특성

김명철,이시훈,김종택 한국화학공학회 1989 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.27 No.5

양이온 교환된 faujasite에 대하여 적외선 분광법, X선 회절분석 및 X선 형광분석법을 이용하여 연구하였다. 적외선 흡수띠의 이동이나 Si/Al비 및 결정성의 정도를 고찰하였다. 양이온 교환된 faujasite에 대한 적외선 흡수띠를 분해하먼 T-O(T : Al 또는 Si)의 진동파수가 940-1051㎝^(-1)(띠 A), 1000-1100㎝^(-1)(띠 B), 1097-1190㎝^(-1)(띠 C), 680-730㎝^(-1)(띠 D), 748-780㎝^(-1)(띠 E) 영역에서 나타났다. 띠 A와 E는 각각 Al-O의 비대칭 신축진동(υ_1) 및 대칭 신축진동(υ_2)에 의한 것으로 볼 수 있다. 띠 C와 D는 Si-O의 비대칭 신측진동(υ_3)과 대칭 신축진동(υ_2)에 의한 것으로 각각 보여진다. 띠 B는 Si-O의 비대칭 신축진동(υ_1)과 Al-O의 비대칭 신축진동(υ_3)의 띠가 겹쳐져서 나타난 것으로 볼 수 있다. The cation-exchanged faujasite were characterized and studied by infrared spectrometer, X-ray fluorescence spectrometer and X-ray diffractometer. The shift of i.r. absorption band, Si/Al ratio and degree of crystallinity were studied respectively. The deconvoluted bands of spectra for the cation-exchanged faujasite corresponding T-O vibration frequency appeared at 940-1050 ㎝^(-1) (band A), 1000-1100 ㎝^-1 (band B), 1097-1190 ㎝^-1 (band C), 680-730 ㎝^-1 (band D), and 748-780 ㎝^-1 (band E). The bands A and E were assigned to the asymmetric stretching(υ_1) and symmetric stretching (υ_2) of Al-O respectively. The bands C and D were assigned to the asymmetric stretching (υ_3) and symmetric stretching (υ_2) of Si-O respectively. The band B was assigned to the overlapping of asymmetric stretching (υ_1) of Si-O and asymmetric stretching (υ_3) of Al-O.

폐암과 동반되어 나타난 기관기관지병증 골연골형성증 1예

이영진,전현수,박시형,김모세,김현주,이승헌,이영민,이현욱,이현경 仁濟大學校 白病院 2010 仁濟醫學 Vol.31 No.-

Tracheobronchopathia osteochondroplastica (TPO) is a rare benign disease of unknown etiology characterized by multiple cartilaginous or bony submucosal nodules, which project into the tracheobronchial lumen. Although some disorders were reported combined with TPO, these seemed to be considered casual. We report a case of TPO that combined with adenocarcinoma of lung. She was 50-year-old non smoking woman presented with chronic cough with right chest pain. Lung mass on right lower lobe was found on chest x-ray, so lung cancer was suspected. Multiple scattered whitish small elevations from trachea to bronchial trees were found on bronchoscopic exam. We mistook these lesions for metastases from lung cancer and biopsies of these lesions were done. Transbronchial biopsy for right lower lobe mass lesion was also done. But biopsies from trachea and bronchus revealed TPO rather than lung cancer. Transbronchial lung biopsy of right lower lobe mass was diagnosed adenocarcinoma of lung. So TPO combined with adenocarcinoma of lung was diagnosed.

A Study on Improvement and Degradation of Si/SiO₂ Interface Property for Gate Oxide with TiN Metal Gate

Lee, Byung-Hyun,Kim, Yong-Il,Kim, Bong-Soo,Woo, Dong-Soo,Park, Yong-Jik,Park, Dong-Gun,Lee, Si-Hyung,Rho, Yong-Han The Korean Institute of Electrical and Electronic 2008 Transactions on Electrical and Electronic Material Vol.9 No.1

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

석탄회분의 융착형성 연구

이시훈,박주식,임영준,김형택 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1

본 연구에서는 DTF를 이용하여 준역청탄인 Alaska탄의 회분과 deposit을 제조하고 조성을 분석하여 각각의 조성이 용융성에 미치는 영향을 고찰하였으며 ASTM 회분의 결과와 비교하였다. ASTM 회분은 alumina, silica, mullite, Ca-com-pound 등이 결정성으로 존재하는 반면 DTF 회분은 표면에 K, Fe, Ca 등이 농축된 구형의 drop이 만들어지는 것을 알 수 있었다. 또한 DTF 회분에는 mullite만이 결정성으로 존재하였다. Deposit은 용융후 고형화된 glass phase로 만들어 졌는데 Fe는 Fe^(3+) silicate로 전이되고 deposit하부에 Si가 농축되는 것으로부터 석탄 내의 무기물 조성 중에 용융을 지배하는 것은 Si인 것을 알 수 있었다. Alaska탄은 ASTM 회분분석결과로부터는 용융성이 강하게 예측되었으나 DTF에서 형성된 deposit 분석결과 표면에 부착강도를 낮게 하는 Ca가 농축되어 열전달면에서의 제거는 용이한 것으로 판단되었다. Ash and deposits were made using Alaska sub-bituminous coal in a drop tube furnace(DTF) and the effects of their compositions on fusion were compared with those of the ashes prepared from the ASTM aching procedure. It has been found that the ASTM ash includes alumina, silica, mullite, and Ca compounds as crystalline phases, whereas the DTF ash includes spherical drops with K, Fe, and Ca condensed on the surface. In a DTF ash, only mullite existed as crystalline phase. 'Che deposits existed as glass phases which were formed by solidification from melts, and Fe was transformed to Fe^(3+) silicate and Si was concentrated on the lower part of the deposit. This fact indicates that, among various inorganic elements in coal, Si controls the fusion. Although it was initially predicted that Alaska coal ash have strong slagging propensity based on the results of ASTM ash characterization, the results of analysis of the DTF deposits shows that the deposits can be easily removed from the heat transfer area because it is enriched with Ca which reduces the strength of its adhesion to the solid surface.