• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.411-420
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• 2020

Undesirable interfacial reactions between the cathode and sulfide electrolyte deteriorate the electrochemical performance of all-solid-state cells based on sulfides, presenting a major challenge. Surface modification of cathodes using stable materials has been used as a method for reducing interfacial reactions. In this work, a precursor-based surface modification method using Zr and Mo was applied to a LiNi_0.6Co_0.2Mn_0.2O₂ cathode to enhance the interfacial stability between the cathode and sulfide electrolyte. The source ions (Zr and Mo) coated on the precursor-surface diffused into the structure during the heating process, and influenced the structural parameters. This indicated that the coating ions acted as dopants. They also formed a homogenous coating layer, which are expected to be layers of Li-Zr-O or Li-Mo-O, on the surface of the cathode. The composite electrodes containing the surface-modified LiNi_0.6Co_0.2Mn_0.2O₂ powders exhibited enhanced electrochemical properties. The impedance value of the cells and the formation of undesirable reaction products on the electrodes were also decreased due to surface modification. These results indicate that the precursor-based surface modification using Zr and Mo is an effective method for suppressing side reactions at the cathode/sulfide electrolyte interface.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권1호
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• pp.21-25
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• 2002

To maximize and sustain the productivity of Monascus pigments, various environmental and nutritional parameters, such as the initial moisture content, pH, inoculum size, sample size, and nutrient supplement, that influence pigment production were evaluated in solid-state cultures as follows: initial moisture content, $50\%;$ pH, 6.0; inoculum size $1\;\times\;10^4$ spore cells $(grams\;of\;dry\;solid\;substrate)^{-1};$ sample size, 300 g. All supplementary nutrients (carbon, nitrogen, and mineral sources) added has inhibitory effects on the cell growth and red pigment production. In open tray culture the maximum biomass yield and specific productivity of red pigments were 223 mg DCW $(grams\;of\;initial\;dry\;substrate)^{-1}$ and, $47.6\;OD_{500}\;(DCW\;grams)^{-1}h^h{-1}$ respectively.

• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.282-290
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• 2020

In this article, we report the effect of blended cathode materials on the performance of all-solid-state lithium-ion batteries (ASLBs) with oxide-based organic/inorganic hybrid electrolytes. LiFePO₄ material is good candidates as cathode material in PEO-based solid electrolytes because of their low operating potential of 3.4 V; however, LiFePO₄ suffers from low electric conductivity and low Li ion diffusion rate across the LiFePO₄/FePO₄ interface. Particularly, monoclinic Li₃V₂(PO₄)₃ (LVP) is a well-known high-power-density cathode material due to its rapid ionic diffusion properties. Therefore, the structure, cycling stability, and rate performance of the blended LiFePO₄/Li₃V₂(PO₄)₃ cathode material in ASLBs with oxidebased inorganic/organic-hybrid electrolytes are investigated by using powder X-ray diffraction analysis, field-emission scanning electron microscopy, Brunauer-Emmett-Teller sorption experiments, electrochemical impedance spectroscopy, and galvanostatic measurements.

• Steel and Composite Structures
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• 제33권3호
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• pp.463-472
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• 2019

Initial thermo-elastic and steady state creep deformation of a rotating functionally graded simple blade is studied using first-order shear deformation theory. A variable thickness model for cantilever beam has been considered. The blade geometry and loading are defined as functions of length so that one can define his own blade profile and loading using any arbitrary function. The blade is subjected to a transverse distributed load, an inertia body force due to rotation and a distributed temperature field due to a thermal gradient between the tip and the root. All mechanical and thermal properties except Poisson's ratio are assumed to be longitudinally variable based on the volume fraction of reinforcement. The creep behaviour is modelled by Norton's law. Considering creep strains in stress strain relation, Prandtl-Reuss relations, Norton' law and effective stress relation differential equation in term of effective creep strain is established. This differential equation is solved numerically. By effective creep strain, steady state stresses and deflections are obtained. It is concluded that reinforcement particle size and form of distribution of reinforcement has significant effect on the steady state creep behavior of the blade.

• 한국전기전자재료학회논문지
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• 제36권6호
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• pp.627-632
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• 2023

Lithium-ion batteries are widely used in various applications, including electric vehicles and portable electronics, due to their high energy density and long cycle life. The performance of lithium-ion batteries can be improved by using solid electrolytes, in terms of higher safety, stability, and energy density. Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) is a promising solid electrolyte for all-solid-state lithium batteries due to its high ionic conductivity and excellent stability. However, the ionic conductivity of LATP needs to be improved for commercializing all-solid-state lithium battery systems. In this study, we investigate the microstructures and ionic conductivities of LATP by incorporating B₂O₃ glass ceramics. The smaller grain size and narrow size distribution were obtained after the introduction of B₂O₃ in LATP, which is attributed to the B₂O₃ glass on grain boundaries of LATP. Moreover, higher ionic conductivity can be obtained after B₂O₃ incorporation, where the optimal composition is 0.1 wt% B₂O₃ incorporated LATP and the ionic conductivity reaches 8.8×10^-5 S/cm, more than 3 times higher value than pristine LATP. More research could be followed for having higher ionic conductivity and density by optimizing the processing conditions. This facile approach for establishing higher ionic conductivity in LATP solid electrolytes could accelerate the commercialization of all-solid-state lithium batteries.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2257-2262
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• 2014

$C_{60}$ is widely investigated because of its unique structure. But its applications in solid propellant seem to be relatively neglected. $C_{60}$ has more outstanding features than carbon black which is widely used as a catalyst ingredient of solid propellant. To combine the advantages of fullerene and lead salts, another good composite in propellant catalysts, we synthesized a kind of fullerene phenylalanine lead salt (FPL) and explored its thermal performances by differential thermal analysis (DTA) and thermogravimetry analysis (TGA). The results show it undergoes four exothermic processes started from 408 K. Combined TGA and X-ray diffractometer (XRD), the decomposition mechanism of FPL was derived by TG-IR and comparing IR spectra of FPL and its residues after burned to $327^{\circ}C$, $376^{\circ}C$ and $424^{\circ}C$, respectively. Effect of FPL on the decomposition characteristic of hexogen (RDX), a type of explosive in propellant, has been investigated using DTA at different heating rate, which shows the decomposition temperatures of the explosive are all reduced by more than 20 K. The corresponding activation energy ($E_a$) is decreased by $30kJ{\cdot}mol^{-1}$. So FPL has potential application as a combustion catalyst in solid propellant.

• 설비공학논문집
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• 제12권1호
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• pp.1-11
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• 2000

This study investigates the problem of phase change from liquid to solid in the inviscid stagnation flow. The solution of dimensionless governing equations is determined by the three dimensionless parameters of (temperature ratio/conductivity ratio), Stefan number, and diffusi-vity ratio. The solution at the initial stage of freezing is obtained by expanding it in powers of time, and the final equilibrium state is determined from the steady-state governing equations. The equilibrium state is dependent on (temperature ratio/conductivity ratio), but is independent of Stefan number and diffusivity ratio. The effect of fluid flow on the pure conduction problem can be clearly seen from the solution of the initial stage and the final equilibrium state, and the characteristics of the solidification process for all the dimensionless parameters are elucidated.

• 전기화학회지
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• 제24권4호
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• pp.100-105
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• 2021

최근 리튬이차전지의 안전성을 향상시킨 전고체 전지가 많은 관심의 대상이 되고 있으나 전도성 세라믹 또는 고체 고분자 전해질을 적용한 고체전지는 높은 계면 저항, 부반응 등과 같은 문제점을 지니고 있어 전기화학적 특성이 낮다. 기존 전고체 전지의 이러한 문제점을 해결하기 위하여 복합고체 전해질이 제안되었으며 본 연구에서는 나시콘 구조의 나노 입자 Li_1.5Al_0.5Ti_1.5P₃O₁₂ (LATP) 전도성 세라믹, PVdF-HFP, 카보네이티 기반 액체전해질을 복합화 하여 유사고체 전해질을 제작하였다. 이 복합고체 전해질은 5.6 V의 높은 전압 안전성을 가지며 리튬이온의 탈리-착리 테스트에서 리튬 금속전극의 덴드라이트 성장 억제 효과가 있음을 보여준다. 또한 복합고체 전해질을 적용한 LiNi_0.83Co_0.11Mn_0.06O₂ (NCM811)기반 전지에서 4.8 V의 높은 충전 종지 전압에도 241.5 mAh/g의 높은 방전 용량을 나타내며 안정적인 전기화학 반응이 일어난다. NCM811 기반 전지의 90도 충전-방전 중에도 전지의 단락이나 폭발 없이 139.4 mAh/g 방전 용량을 보인다. 따라서 LATP기반 복합고체 전해질은 리튬이차전지의 안전성과 전기화학적 특성을 향상 시킬 수 있는 효과적인 방법임을 알 수 있다.

• Journal of Pharmaceutical Investigation
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• 제31권3호
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• pp.167-172
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• 2001

All-trans retinoic acid (ATRA), vitamin A acid, has been shown to exert anticancer activity in a number of types of cancers, particularly in acute promyelocytic leukaemia (APL). Due to its highly variable bioavailability and induction of its own metabolism after oral treatment, development of parenteral dosage forms are required. However, its poor aqueous solubility and chemical unstability give major drawbacks in parenteral administration. This study was undertaken to investigate a possibility to develop a parenteral formulation of ATRA by employing solid lipid nanoparticle (SLN) as a carrier. By optimizing the production parameters and the composition of SLNs, SLNs with desired mean particle size (<100 nm) as a parenteral dosage form could be produced from trimyristin (as solid lipid), Egg phosphatidylcholine and Tween 80 (as SLN stabilizer). The mean particle size of SLN formulation of ATRA was not changed during storage, suggesting its physical stability. Thermal analysis confirmed that the inner lipid core of SLNs exist at solid state. The mean particle size of ATRA-loaded SLNs was not significantly changed by the lyophilization process. ATRA could be efficiently loaded in SLNs, while maintaining its anticancer activity against HL-60, a well-known APL cell line. Furthermore, by lyophilization, ATRA loaded in SLN could be retained chemically stable during storage. Taken together, our present study demonstrates that physically and chemically stable ATRA formulation adequate for parenteral administration could be obtained by employing SLN technology.

• Journal of Electrochemical Science and Technology
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• 제9권2호
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• pp.126-132
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• 2018

For the first time, an innovative approach using P(VDF-TrFE) as a polymer electrolyte for high efficiency, all-solid-state supercapacitors is presented. The polymer electrolyte was successfully achieved by dissolving P(VDF-TrFE) copolymers in dimethylformamide (DMF). Thermal analysis and infrared spectroscopy revealed excellent thermal stability up to $400^{\circ}C$ and copolymer's interaction with DMF. Electrochemical capacitors fabricated using P(VDF-TrFE) in DMF and ZnO NWs demonstrated high capacitive performance. Furthermore, the gel electrolyte-based supercapacitors demonstrated excellent mechanical durability up to a bend angle of $120^{\circ}$. Novel P(VDF-TrFE) electrolytes could be a promising approach for applications in flexible, fabric-based, and high-efficiency energy devices.