Search

Your search keyword '"Park, Min-Sik"' showing total 909 results
Start Over Author "Park, Min-Sik"
909 results on '"Park, Min-Sik"'

303. The origin of the stabilized simple-cubic structure in Po

Author

Min, B. I., Shim, J. H., Park, Min Sik, Kim, Kyoo, Kwon, S. K., and Youn, S. J.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

The origin of the stabilized simple-cubic (SC) structure in Po is explored by using the first principle band calculations. We have found that the prime origin is the inherent strong spin-orbit (SO) interaction in Po, which suppresses the Peierls-like structural instability as usually occurs in p-bonded systems. Based on the systematic analysis of electronic structures, charge densities, Fermi surfaces, and susceptibilities of Se, Te, and Po, we have proved that the stable crystal structure in VIA elements is determined by the competition between the SO splitting and the crystal field splitting induced by the low-symmetry structural transition. The trigonal structure is stabilized in Se and Te by the larger crystal field splitting than the SO splitting, whereas in Po the SC structure is stabilized by the large SO splitting., 4 pages, 4figures

Published
2005

304. Enhanced Li+ conduction in perovskite Li3xLa2/3−x□1/3−2xTiO3 solid-electrolytes via microstructural engineering.

Author

Kwon, Woo Ju, Kim, Hyeongil, Jung, Kyu-Nam, Cho, Woosuk, Kim, Sung Hyun, Lee, Jong-Won, and Park, Min-Sik

Abstract

Solid electrolytes are key to the evolution of all-solid-state lithium batteries as next-generation energy storage systems. High ionic conductivity and stability of solid electrolytes are critical requirements for designing reliable all-solid-state lithium batteries. Perovskite-type lithium lanthanum titanates Li3xLa(2/3)−x□(1/3)−2xTiO3 (LLTOs) have received much attention as a potential inorganic solid electrolyte to replace current organic liquid electrolytes; however, the practical use of LLTOs is limited by their low total conductivity. With the aim of improving the ionic conductivity, we investigated a correlation between the microstructures and Li+ conducting properties of LLTO perovskites. We show that the total conductivity of LLTOs is dominated by the domain boundary resistance, and the synthesis condition of the electrolyte (sintering temperature and Li concentration) has a crucial role in modifying the microstructure and composition of the domain boundaries to significantly reduce the boundary resistance. By controlling the sintering temperature and Li content, in particular, a total Li+ conductivity as high as 4.8 × 10−4 S cm−1 can be achieved at room temperature. The findings of this study would be essential in understanding Li+ conducting behaviors and in developing highly conductive perovskite-type LLTO solid electrolytes. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

305. Highly enhanced electrochemical activity of Ni foam electrodes decorated with nitrogen-doped carbon nanotubes for non-aqueous redox flow batteries.

Author

Lee, Jungkuk, Park, Min-Sik, and Kim, Ki Jae

Subjects
*ELECTRODES, *NITROGEN, *CARBON nanotubes, *OXIDATION-reduction reaction, *FLOW batteries
Abstract

Nitrogen-doped carbon nanotubes (NCNTs) are directly grown on the surface of a three-dimensional (3D) Ni foam substrate by floating catalytic chemical vapor deposition (FCCVD). The electrochemical properties of the 3D NCNT-Ni foam are thoroughly examined as a potential electrode for non-aqueous redox flow batteries (RFBs). During synthesis, nitrogen atoms can be successfully doped onto the carbon nanotube (CNT) lattices by forming an abundance of nitrogen-based functional groups. The 3D NCNT-Ni foam electrode exhibits excellent electrochemical activities toward the redox reactions of [Fe (bpy) 3 ] 2+/3+ (in anolyte) and [Co(bpy) 3 ] +/2+ (in catholyte), which are mainly attributed to the hierarchical 3D structure of the NCNT-Ni foam electrode and the catalytic effect of nitrogen atoms doped onto the CNTs; this leads to faster mass transfer and charge transfer during operation. As a result, the RFB cell assembled with 3D NCNT-Ni foam electrodes exhibits a high energy efficiency of 80.4% in the first cycle; this performance is maintained up to the 50 th cycle without efficiency loss. [ABSTRACT FROM AUTHOR]

Published
2017
Full Text
View/download PDF

306. Defect mediated lithium adsorption on graphene-based silicon composite electrode for high capacity and high stability lithium-ion battery.

Author

Chang, Hongjun, Park, Min-Sik, Kim, Jung Ho, and Moon, Janghyuk

Subjects
*SILICON alloys, *LITHIUM-ion batteries, *COMPOSITE materials, *DENSITY functional theory, *ELECTRIC conductivity, *ADSORPTION (Chemistry), *ANODES
Abstract

[Display omitted] • Defect in graphene-silicon(d-Gr/Si) composites enhances electrochemical performance. • Li adsorption energies in the d-Gr/Si were less than -0.6 eV and 0.25 eV at pristine Gr/Si. • Defected Gr/Si is more thermionically stable than pristine Gr/Si. • Charge transfer on defects improves electrical conduction and mechanical strength at interfaces. • Our analyses elucidate that defect engineering enhances Li capacity and mechanical strength. Carbon-coated silicon materials are considered as promising anode materials in high-capacity lithium-ion batteries (LIBs). Theoretically, using graphene as the anode material in the LIB would afford high electrical conductivity, mechanical stability of Si, and suppression of the unstable solid–electrolyte interface. However, its usage is hindered by its electrochemical characteristic, which is not electrochemically active when combined with lithium. Therefore, research on graphene as the anode and coated material in LIBs has been conducted using defect engineering to enhance the storage capacity of graphene. Although the electrochemical characteristics of various defects in graphene have been studied experimentally and theoretically, graphene-based composite anode materials such as graphene–silicon composite electrodes have rarely been studied from the electrochemical and mechanical perspectives. In this study, lithium adsorptions are conducted on various defected graphene and graphene–silicon composites using density functional theory calculation. The formation energies of Li on the various defected graphene are assessed, and the mechanical strengths of the graphene–silicon composites are analyzed. Our calculations validate that the defects in graphene enhance the electrochemical adsorptions and interfacial mechanical strengths of the graphene and graphene–silicon composites. During lithiation, the defects mediate greater interfacial adhesion of the silicon–graphene composite. Hence, we elucidate that defected graphene increases the electro-chemo mechanical stabilities of silicon composites in high-capacity LIBs. [ABSTRACT FROM AUTHOR]

Published
2023
Full Text
View/download PDF

307. Effective Polysulfide Rejection by Dipole-Aligned BaTiO3 Coated Separator in Lithium-Sulfur Batteries.

Author

Yim, Taeeun, Han, Seung Ho, Park, Nam Hwan, Park, Min‐Sik, Lee, Ji Hoon, Shin, Jaeho, Choi, Jang Wook, Jung, Yongju, Jo, Yong Nam, Yu, Ji‐Sang, and Kim, Ki Jae

Subjects
LITHIUM sulfur batteries, POLYSULFIDES, ELECTRIC fields, BARIUM titanate films, ELECTRODES
Abstract

Although the exceptional theoretical specific capacity (1672 mAh g−1) of elemental sulfur makes lithium-sulfur (Li-S) batteries attractive for upcoming rechargeable battery applications (e.g., electrical vehicles, drones, unmanned aerial vehicles, etc.), insufficient cycle lives of Li-S cells leave a substantial gap before their wide penetration into commercial markets. Among the key features that affect the cyclability, the shuttling process involving polysulfides (PS) dissolution is most fatal. In an effort to suppress this chronic PS shuttling, herein, a separator coated with poled BaTiO3 or BTO particles is introduced. Permanent dipoles that are formed in the BTO particles upon the application of an electric field can effectively reject PS from passing through the separator via electrostatic repulsion, resulting in significantly improved cyclability, even when a simple mixture of elemental sulfur and conductive carbon is used as a sulfur cathode. The coating of BTO particles also considerably suppresses thermal shrinkage of the poly(ethylene) separator at high temperatures and thus enhances the safety of the cell adopting the given separator. The incorporation of poled particles can be universally applied to a wide range of rechargeable batteries (i.e., metal-air batteries) that suffer from cross-contamination of charged species between both electrodes. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

315. Oriented TiO2 nanotubes as a lithium metal storage medium

Author

Kim, Jae-Hun, primary, Kang, Hee-Kook, additional, Woo, Sang-Gil, additional, Jeong, Goojin, additional, Park, Min-Sik, additional, Kim, Ki Jae, additional, Yu, Ji-Sang, additional, Yim, Taeeun, additional, Jo, Yong Nam, additional, Kim, Hansu, additional, Zhu, Kai, additional, and Kim, Young-Jun, additional

Published
2014
Full Text
View/download PDF

322. Back Cover: Zr4+Doping in Li4Ti5O12Anode for Lithium-Ion Batteries: Open Li+Diffusion Paths through Structural Imperfection (ChemSusChem 5/2014)

Author

Kim, Jae-Geun, primary, Park, Min-Sik, additional, Hwang, Soo Min, additional, Heo, Yoon-Uk, additional, Liao, Ting, additional, Sun, Ziqi, additional, Park, Jong Hwan, additional, Kim, Ki Jae, additional, Jeong, Goojin, additional, Kim, Young-Jun, additional, Kim, Jung Ho, additional, and Dou, Shi Xue, additional

Published
2014
Full Text
View/download PDF

334. Electronic structures and ferromagnetism in transition metals codoped ZnO

Author

Park, Min Sik and Min, B. I.

Subjects
Condensed Matter::Materials Science, Condensed Matter - Materials Science, Quantitative Biology::Neurons and Cognition, Condensed Matter::Other, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Condensed Matter::Strongly Correlated Electrons, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
Abstract

We have investigated electronic structures and magnetic properties of potential ZnO based diluted magnetic semiconductors: (Fe, Co) and (Fe, Cu) codoped ZnO. The origins of ferromagnetism are shown to be different between two. (Fe, Co) codoped ZnO does not have a tendency of Fe-O-Co ferromagnetic cluster formation, and so the double exchange mechanism will not be effective. In contrast, (Fe, Cu) codoped ZnO has a tendency of the Fe-O-Cu ferromagnetic cluster formation with the charge transfer between Fe and Cu, which would lead to the ferromagnetism through the double-exchange mechanism. The ferromagnetic and nearly half-metallic ground state is obtained for (Fe, Cu) codoped ZnO., 6 pages, 6 figures

Published
2003

335. Controlled Ag-driven superior rate-capability of Li4Ti5O12 anodes for lithium rechargeable batteries

Author

Kim, Jae-Geun, Shi, Dongqi, Park, Min-Sik, Jeong, Goojin, Heo, Yoon-Uk, Seo, Minsu, Kim, Young Jun, Kim, Jung Ho, Dou, S X, Kim, Jae-Geun, Shi, Dongqi, Park, Min-Sik, Jeong, Goojin, Heo, Yoon-Uk, Seo, Minsu, Kim, Young Jun, Kim, Jung Ho, and Dou, S X

Abstract

The morphology and electronic structure of a Li4Ti5O12 anode are known to determine its electrical and electrochemical properties in lithium rechargeable batteries. Ag-Li4Ti5O12 nanofibers have been rationally designed and synthesized by an electrospinning technique to meet the requirements of one-dimensional (1D) morphology and superior electrical conductivity. Herein, we have found that the 1D Ag-Li4Ti5O12 nanofibers show enhanced specific capacity, rate capability, and cycling stability compared to bare Li4Ti5O12 nanofibers, due to the Ag nanoparticles (<5 >nm), which are mainly distributed at interfaces between Li4Ti5O12 primary particles. This structural morphology gives rise to 20% higher rate capability than bare Li4Ti5O12 nanofibers by facilitating the charge transfer kinetics. Our findings provide an effective way to improve the electrochemical performance of Li4Ti5O12 anodes for lithium rechargeable batteries. [Figure not available: see fulltext.] 2013 Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Published
2013

337. Spintronic and electrochromic device based on Li-intercalated transition-metal doped anatase $\rm TiO_2$

Author

Park, Min Sik and Min, B. I.

Subjects
Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences
Abstract

We have explored the effects of the Li intercalation on the electronic and magnetic properties of transition-metal (TM) doped anatase TiO$_2$. By Li intercalation, Mn-doped TiO$_2$ exhibits the insulator to metal transition. On the other hand, Li-intercalated Fe-doped TiO$_2$ has the insulating ground state for low concentration of Li/Ti=0.067, but the metallic ground state for high concentration of Li/Ti=0.133. We discuss the $n$-type carrier induced ferromagnetism in Li-intercalated TM-doped anatase TiO$_2$. Based on the Li-intercalated TM-doped anatase TiO$_2$, we propose a potential spintronic and electrochromic device controlled by the electric-field., 4 pages, 4 figures

Published
2002

338. Electronic structures of doped anatase $\rm TiO_{2}$: $\rm Ti_{1-x}M_{x}O_{2}$ (M=Co, Mn, Fe, Ni)

Author

Park, Min Sik, Kwon, S. K., and Min, B. I.

Subjects
Condensed Matter::Materials Science, Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Condensed Matter::Strongly Correlated Electrons
Abstract

We have investigated electronic structures of a room temperature diluted magnetic semiconductor : Co-doped anatase $\rm TiO_{2}$. We have obtained the half-metallic ground state in the local-spin-density approximation(LSDA) but the insulating ground state in the LSDA+$U$+SO incorporating the spin-orbit interaction. In the stoichiometric case, the low spin state of Co is realized with the substantially large orbital moment. However, in the presence of oxygen vacancies near Co, the spin state of Co becomes intermediate. The ferromagnetisms in the metallic and insulating phases are accounted for by the double-exchange-like and the superexchange mechanism, respectively. Further, the magnetic ground states are obtained for Mn and Fe doped $\rm TiO_{2}$, while the paramagnetic ground state for Ni-doped $\rm TiO_{2}$., 5 pages, 4 figures

Published
2002

339. The comparison between nanostructure control and other modifications to improve the electrochemical performance of SnO

Author

Kang, Yong-Mook, Park, Min-Sik, Liu, Hua-Kun, Dou, S. X., Kang, Yong-Mook, Park, Min-Sik, Liu, Hua-Kun, and Dou, S. X.

Abstract

With an advent of the ubiquitous era, the demand for rechargeable batteries with a higher energy density is getting more and more critical. It is because applications are emerging such as electric vehicles and various types of portable electronic devices. Carbonaceous materials are commonly adopted as the anode material for commercial lithium-ion secondary batteries because it can reversibly intercalate or de-intercalate Li ion. However, low capacity of carbon has become a limiting factor in wider applications, and high capacity alternative to carbonaceous material has thus been sought for. Even if tin and silicon have been considered as one of the most attractive options for high energy density purpose, its poor cyclic properties have been delaying its commercialization.

Published
2010

340. Effects of low-temperature carbon encapsulation on the electrochemical performance of SnO2 nanopowders

Author

Park, Min-Sik, Kang, Yong-Mook, Kim, Jung Ho, Wang, Guoxiu, Dou, S X, Liu, Hua-Kun, Park, Min-Sik, Kang, Yong-Mook, Kim, Jung Ho, Wang, Guoxiu, Dou, S X, and Liu, Hua-Kun

Abstract

Carbon encapsulated SnO2 composites were prepared by a thermal evaporation and decomposition of malic acid (C4H6O5) at low temperature to demonstrate their potential use for application in lithium ion batteries. The solution-based chemical approach was effective for coating amorphous C layers on the surface of SnO2 nanopowders without significant oxygen reduction. The desirable crystalline structure and oxygen stoichiometry of SnO2 were maintained, while amorphous C homogeneously encapsulated SnO2 nanopowders. The strong enhancement on the anodic reversible capacity and cyclic performance was discussed for the C-encapsulated SnO2 composites. It is expected that the low-temperature processing can be a new general route for preparing composites with C from economic point of view.

Published
2008

341. Synthesis and characterization of nanostructured electrode materials for rechargeable lithium ion batteries

Author

Park, Min Sik and Park, Min Sik

Abstract

State-of-the-art rechargeable lithium-ion battery technology has now paved the way for advanced energy storage systems to take their place in a variety of portable electronics. High cell voltage, good cycle life, and an attractive combination of energy and power generation are on the verge of being guaranteed for high-power and large-scale applications, such as plug-in hybrid vehicles. This investigation examines the circumstances attending the development of the rechargeable lithium-ion battery, to seek a better understanding of the factors affecting its electrochemical performance. The major objective of this work is to determine the advantages and drawbacks of tin dioxide (SnO2) nanostructured materials as alternative anode materials and to suggest promising structural modifications in order to improve their electrochemical properties. Another important objective is to identify the correlation between electrochemical performance and particle size minimization in the lithium iron phosphate (LiFePO4) system, a promising cathode material, and to give further evidence supporting the incomplete room-temperature reaction mechanism. The selection and assembly of nanostructured materials have been considered as central issues in the development of alternative anode materials that possess higher capacity and better cyclic retention compared to commercial graphite. SnO2 has shown high capacity and a relatively low reaction potential with Li+, and is thus under consideration as a possible candidate for high-power and high-energy applications. We have synthesized various types of SnO2 nanostructured materials, such as nanopowders, nanowires, and nanotubes in this work, and their electrochemical properties have been carefully compared in order to demonstrate the effects of their morphological differences on the electrochemical performance, based on thermodynamic and kinetic considerations. By incorporating structural modifications into the SnO2 nanostructured materials, we ha

Published
2008

344. Effect of chemical reactivity of polysulfide toward carbonate-based electrolyte on the electrochemical performance of Li–S batteries

Author

Yim, Taeeun, primary, Park, Min-Sik, additional, Yu, Ji-Sang, additional, Kim, Ki Jae, additional, Im, Keun Yung, additional, Kim, Jae-Hun, additional, Jeong, Goojin, additional, Jo, Yong Nam, additional, Woo, Sang-Gil, additional, Kang, Kyoung Seok, additional, Lee, Ingurl, additional, and Kim, Young-Jun, additional

Published
2013
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results