Honeycomb-layer structured Na3Ni2BiO6 as a high voltage and long life cathode material for sodium-ion batteries

Bhange, D.,Ali, G.,Kim, D. H.,Anang, D.,Shin, T.,Kim, M. G.,Kang, Y. M.,Chung, K.,Nam, K. W. Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.3

<P>The need to find sodium ion battery (SIB) cathodes with high voltage, capacity and improved cycle life has stimulated research on sodium containing layered transition metal oxides. With this perspective, the electrochemical properties of highly ordered, honeycomb layered Na3Ni2BiO6 with a monoclinic superstructure are explored as a cathode material in SIBs. It has been demonstrated that Na3Ni2BiO6 delivers a discharge capacity of 106 mA h g(-1), having high voltage plateaus at 3.50 and 3.25 V, with marginal capacity fading after 50 cycles. Operando X-ray diffraction studies during charging/discharging reveal two reversible two-phase transition mechanisms (initial O3 phase -> P3 intermediate phase -> O1 final phase) during sodium extraction. Ex situ X-ray absorption spectroscopy reveals the charge compensation mechanism for the reversible Ni3+/Ni2+ as an active redox couple while Bi5+ being inactive during cycling. Extended X-ray absorption fine structure analysis shows highly reversible local structural changes around both Ni and Bi atoms occurring during electrochemical cycling. In addition, unique local structure changes especially around Ni atoms due to the honeycomb ordering and size mismatch between Ni2+ and Bi5+ ions are revealed by EXAFS analysis during charging and discharging, which is quite different from the local structure changes in regular layer structured NaMO2 (M = transition metals) cathode materials. The present results suggest that honeycomb layered metal oxides with the general formula, Na3M((II)) M-2(V) O-6, can be considered as candidates for high voltage and long life cathode materials for SIBs.</P>

Improving the sodium storage capacity of tunnel structured Na_xFe_xTi_2-xO₄ (x = 1, 0.9 & 0.8) anode materials by tuning sodium deficiency

Bhange, Deu S.,Ali, Ghulam,Kim, Ji-Young,Chung, Kyung Yoon,Nam, Kyung-Wan Elsevier 2017 Journal of Power Sources Vol.366 No.-

<P><B>Abstract</B></P> <P>Due to their abundance and environmentally benign nature, iron and titanium present as the most attractive potential elements for use in rechargeable sodium-ion batteries (SIBs). Accordingly, two structurally different Fe and Ti based compounds, stoichiometric NaFeTiO<SUB>4</SUB> and sodium deficient Na<SUB>x</SUB>Fe<SUB>x</SUB>Ti<SUB>2-x</SUB>O<SUB>4</SUB> (where x = 0.9, and 0.8), are explored as anode materials for SIBs. Their structure and sodium storage capacity are systematically investigated by using combined structural and electrochemical analysis. Rietveld refinement analysis reveals that the sodium deficiency leads to the structural transformation from a single-tunnel structure (NaFeTiO<SUB>4</SUB>) to a zigzag-type double-tunnel structure (Na<SUB>0.9</SUB>Fe<SUB>0.9</SUB>Ti<SUB>1.1</SUB>O<SUB>4</SUB> and Na<SUB>0.8</SUB>Fe<SUB>0.8</SUB>Ti<SUB>1.2</SUB>O<SUB>4</SUB>). The series of sodium deficient compounds bears systematic sodium ion vacancies in their structure up to 20%. Sodium deficiency in the Na<SUB>x</SUB>Fe<SUB>x</SUB>Ti<SUB>2-x</SUB>O<SUB>4</SUB> logically provides additional space for accommodating the excess sodium ions as such the Na<SUB>x</SUB>Fe<SUB>x</SUB>Ti<SUB>2-x</SUB>O<SUB>4</SUB> compounds with higher level of sodium deficiency show higher specific capacities than the stoichiometric NaFeTiO<SUB>4</SUB>. All the compounds exhibited very good electrochemical cycling stability, with minimal capacity loss during cycling. The present approach is a model example of improvement in the sodium storage capacity of the anode materials by tuning the chemical composition, and could facilitate the performance improvement of known or new electrode materials for SIBs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Series of Na<SUB>x</SUB>Fe<SUB>x</SUB>Ti<SUB>2-x</SUB>O<SUB>4</SUB> compounds (x = 1, 0.9, and 0.8) are synthesized. </LI> <LI> Na deficiency leads to the structural change from single-to double-tunnel structure. </LI> <LI> Na deficiency logically provides an extra space for housing excess Na ions. </LI> <LI> Sodium storage capacity increases with increasing Na deficiency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Tetrahedral Atom Ordering in a Zeolite Framework: A Key Factor Affecting Its Physicochemical Properties

Shin, Jiho,Bhange, Deu S.,Camblor, Miguel A.,Lee, Yongjae,Kim, Wha Jung,Nam, In-Sik,Hong, Suk Bong American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.27

<P>Three gallosilicate natrolites with closely similar chemical composition but differing in the distribution of Si and Ga over crystallographically different tetrahedral sites (T-sites) show striking differences in their cation exchange performance. The ability to exchange Na<SUP>+</SUP> by the larger alkali metal cations decreases upon increasing the size of the cation, as expected, but also with the degree of T-atom ordering. To seek an insight into this phenomenon, the crystal structures of 11 different zeolites, which show variations in degree of T-atom ordering, nature of countercation, and hydration state, have been refined using synchrotron diffraction data. While the three as-made sodium materials were characterized to have a low, medium, and high degree of ordering, respectively, their pore sizes are close to the size of the bare Na<SUP>+</SUP> cation and much smaller than that of the larger alkali cations, which are nonetheless exchanged into the materials, each one at a different level. Interestingly, large differences are also manifested when the Na<SUP>+</SUP> back-exchange is performed on the dehydrated K<SUP>+</SUP> forms, with crystallographic pore sizes too small even to allow the passage of Na<SUP>+</SUP>. Although the thermodynamic data point to small differences in the enthalpy of the Na<SUP>+</SUP>/K<SUP>+</SUP> exchange in the three materials, comparison of the “static” crystallographic pore sizes and the diameter of the exchanged cations lead us to conclude that during the exchange process these zeolites undergo significant deformations that dynamically open the pores, allowing cation traffic even for Cs<SUP>+</SUP> in the case of the most disordered material. In addition to the very large topological flexibility typical of the natrolite framework, we propose as a hypothesis that there is an additional flexibility mechanism that decreases the rigidity of the natrolite chain itself and is dependent on preferential siting of Si or Ga on crystallographically different T-sites.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-27/ja202739j/production/images/medium/ja-2011-02739j_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja202739j'>ACS Electronic Supporting Info</A></P>

Structural characterization of various alkali cation forms of synthetic aluminosilicate natrolites

Shin, Jiho,Bhange, Deu S.,Park, Min Bum,Hong, Suk Bong Elsevier 2015 Microporous and mesoporous materials Vol.210 No.-

<P><B>Abstract</B></P> <P>The structures of the Na<SUP>+</SUP>, K<SUP>+</SUP>, Rb<SUP>+</SUP>, and Cs<SUP>+</SUP> forms of PST-3 and PST-4, two synthetic aluminosilicate natrolite zeolites with almost completely disordered and ordered distributions of framework Si and Al atoms, respectively, in both hydrated and dehydrated states have been determined using synchrotron powder X-ray diffraction and Rietveld analyses. It was found that the trivalent tetrahedral atom (T-atom) content, as well as the type of extraframework alkali metal cations and the hydration state, is a more important factor governing the framework flexibility of this family of small-pore zeolites than the T-atom distribution.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The structures of various alkali cation forms of PST-3 and PST-4 have been determined. </LI> <LI> Their framework flexibility is highly dependent on the extraframework composition. </LI> <LI> The degree of T-atom ordering alters, to a lesser extent, the framework flexibility. </LI> <LI> PST-3 and PST-4 are more flexible than TNU-3 and TNU-4, their gallosilicate analogs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nickel-titanium oxide as a novel anode material for rechargeable sodium-ion batteries

Kalubarme, R.,Inamdar, A.,Bhange, D. S.,Im, H.,Gosavi, S.,Park, C. J. Royal Society of Chemistry 2016 Journal of Materials Chemistry A Vol.4 No.44

<P>Nickel-titanium oxide (NiTiO3; NTO) of an ilmenite structure that comprises a layered transition-metal octahedral structure, wherein the zigzag open tunnels are possible routes for Na intercalation, can be a potential anode material for sodium (Na) ion batteries (SIBs). In this study, nanocrystalline NTO particles that are of sizes 3 to 5 nm were prepared using a simple hydrothermal process followed by annealing, and the particles were then tested for SIB applications. The pure-NTO electrode that comprises a hexagonal crystal structure and mesoporous morphology demonstrated a reversible capacity of approximately 521 mA h g(-1) that corresponds to a coulombic efficiency of 67% in the first cycle, which further improved to similar to 98% in the following cycles, at an applied specific current of 50 mA g(-1), and stable cycling performance for 200 cycles. Further, due to the synergetic effect of the porous network structure and high surface area, the NTO electrode exhibited an exceptional rate capability, delivering a capacity of 192 mA h g(-1) at a high specific current of 4000 mA g(-1). The excellent cyclability and rate capability of the NTO electrode are attributed to the improved electronic conductivity and highly porous microstructure of the NTO material, whereby fast charge transfer and facile diffusion of the Na-ions to the active sites are enabled.</P>

Security, Vulnerability and Protection of Vehicular On-board Diagnostics

Aastha Yadav,Gaurav Bose,Radhika Bhange,Karan Kapoor,N.Ch.S.N Iyengar,Ronnie D. Caytiles 보안공학연구지원센터 2016 International Journal of Security and Its Applicat Vol.10 No.4

Recent studies have shown that ‘’hacktivists’’ can mount serious attacks on automobiles. The automotive On-Board Diagnostic (OBD) interface enables an efficient way to access information of the in-vehicle electronic system and leaves way for unauthorized access by an intruder. We discover that remote exploitation is feasible via a broad range of attack points such as mechanic tools, CD players, Bluetooth and Tire Pressure Monitoring System. Wireless communications channels allow long distance vehicle control. Finally, the paper discusses the drawbacks of Seed-Key Mechanism to authenticate and provide an extra layer of authentication to help build a safer automotive ecosystem.

新都市開發의 促進方案

申邦鉉 단국대학교 대학원 1983 學術論叢 Vol.7 No.-

The construction of a new city--which is pleasantly inhabitable-has been a human dream with the birth of city on this earth. It has become a more ardent passion than ever, since the existing city-system starts exerting ill effects and presenting injurious influence upon the agreeable inhabitation. However, the desire for new-city development, in the modern connotation, is stemmed out of the rapid urbanization, which followed the Industrial Revolution. In the mid-20-th century, nations in the world attained economic growth successfully, in various degrees, through industrialization in their economy. This resulted in the enormous population movement into industrialized city, and this intensified population concentration raised some critical issues such as the deterioration of city environment, the developmental distances between regions, and so on. In order to meet these needs and to readjust these injurious effects, a great deal of nations have adopted the new-city development as a remedy. As a promoting scheme for new-city development, the present study discusses ⅰ) the goal of development strategy, ⅱ) the expansion of housing-land, ⅲ) the reformation of city-life environment, and ⅳ) the institutional support. The goal of development strategy should notice the industrial, the commercial, the business, and the daily-living facility as well on the additionally developed building-site, and these facilities should be able to function systematically with one another through effectual population flow. As to the expansion of housing-land, this study suggests the establishment of development-pole in the collected development capacity with concentrated development strategy-rather than eith diffused development strategy. In addition, the spill-over effect from the development-pole should be taken into consideration at the same time. For the reformation of city-life environment, the completion of educational facility, the installation of commercial-business facility, and their comfortableness and security need to be supplemented in the planning. Finally, the institutional support for new-city development includes the finance for construction fund, the balanced unit-development by civilian investment. the higher priority for housing construction fund, the timely establishment of self-determining institution fro developmental administration, and the assistance by tax-benefit in the promoting scheme for new-city development proposed by this study.

資本市場에서의 差別的 情報에 관한 硏究

方旴濟 충남대학교 경상대학부설 경영경제연구소 1992 경영논집 Vol.8 No.1

BEHAVIORAL CONSIDERATIONS IN BUDGETING SYSTEMS

Bhang, Woo J. 충남대학교 경상대학부설 경영경제연구소 1980 경영논집 Vol.2 No.1

A Study on the Service Load State Behavior of Reinforced Concrete Plate Member

Bhang, Jee-Hwan,Kang, Won-Ho Korea Concrete Institute 2000 KCI concrete journal Vol.12 No.2

This paper proposes a mechanical model to describe the load-deformation responses of the reinforced concrete plate members under service load state. An Analytical method is introduced on the basis of the rotating crack model which considers equilibrium, compatibility conditions, load-strain relationship of cracked member, and constitutive law for materials. The tension stiffening effect in reinforced concrete structures is taken into account by the average tensile stress-strain relationship from the load-strain relationship for the cracked member and the constitutive law for material. The strain compatibility is used to find out the crack direction because the crack direction is an unknown variable in the equilibrium and compatibility conditions. The proposed theory is verified by the numerous experimental data such as the crack direction, moment-steel strain relationship, moment-crack width relationship. The present paper can provide some basis for the provision of the definition of serviceability for plate structures of which reinforcements are deviated from the principal stresses, because the present code defines the serviceability by the deflection, crack control, vibration and fatigue basically for the skeletal members. The proposed theory is applicable to predict the service load state behavior of a variety of reinforced concrete plate structures such as skew slab bridges, the deck of skew girder bridges.