Publications (47)137.55 Total impact
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Article: Development of a novel and safer energy storage system using a graphite cathode and Nb2O5 anode
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ABSTRACT: A novel energy storage system employing a KS-6 graphite cathode and niobium (V) oxide (Nb2O5) anode was developed with a 1:1 weight ratio of cathode to anode. The cell, with a voltage range of 1.5–3.5 V, showed higher capacity and better cycle performance than those of cells with other voltage ranges. At 1C and 35C rates, this cell delivered 57 and 26 mAh g−1, respectively. A graphite cathode can be increased to approximately 5.2 V, which is well above the LIB cathode material, without causing safety issues, and the operating voltage of the Nb2O5 anode was greater than that of the lithium deposition voltage. In situ X-ray diffraction results at various states of charge indicated that the mechanism of this energy storage system was intercalation and de-intercalation of PF6− and Li+ in the KS-6 graphite cathode and in the Nb2O5 anode. This novel energy storage system was inherently safe because 1) no oxygen is released from cathode materials, 2) no lithium dendrite is used at the anode, and 3) there was no possibility of overcharge from the electrode/electrolyte reaction.Journal of Power Sources 08/2013; 236:145. · 4.95 Impact Factor -
Conference Proceeding: Novel Hybrid Capacitor Composing a Hollow Titania Nanosphere Anode and a KS-6 Cathode
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ABSTRACT: A full cell has been developed using KS-6 and hollow titania nanosphere as cathode and anode materials, respectively, by using 1:1 weight ratio of cathode to anode materials. Thus developed energy storage system exhibits enhanced voltage up to 5.3 V vs. lithium without causing any safety issues. Since the anode is free from lithium deposition the safety of this energy storing device is expected to be very high. The charge/discharge mechanism of the present system exclusively based on intercalation and de-intercalation of PF6 - anion at the cathode (KS-6) and Li+ cation at the anode (hollow titania nanosphere) materials, respectively. In addition, hollow titania spherical structure enhances the rate performance of the device.2012 2nd International Conference on Power and Energy Systems (ICPES 2012); 11/2012 -
Conference Proceeding: Synthesis of ZnO Hollow Nanospheres and Their Electrochemical Reactivity for Lithium-ion Batteries
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ABSTRACT: ZnO hollow nanosphere of size about 32 ± 2 nm is reported using polymeric micelle with core-shell-corona structure as a soft-template. Poly(styrene–b–acrylic acid–b–ethylene oxide) micelles (PS–PAA–PEO) with anionic shell block facilitates the formation of hollow nanospheres through electrostatic interaction of Zn2+ with –COO– ions followed by precipitation/deposition reaction under mild alkaline conditions. X-ray diffraction (XRD) analysis confirmed the formation of pure ZnO phase (Zincite-type) with hexagonal latticestructure (P63mc). Transmission electron microscope (TEM) confirmed the existence of hollow spherical structure with average diameter of 32 ± 2 nm. The hollow particles were also thoroughly characterized by SEM, EDX, FTIR, nitrogen adsorption, and thermal analyses by TG/DTA. The electrochemical characteristics of ZnO hollow nanospheres as anode materials for lithium ion battery are investigated and the obtained results are also compared with dense granular powders. The hollow nanosphere based electrode delivers high initial discharge capacity of 1304 mAh.g–1 at a charge/discharge rate of 0.25 C. More importantly, the nanoconstructed electrodes maintain the structural integrity even after subjecting to high current density.2012 International Conference on Power and Energy Systems (ICPES 2012); 11/2012 -
Article: CeO2 Hollow Nanospheres as Anode Material for Lithium Ion Batteries
Chemistry Letters 05/2012; 41(4):386. · 1.59 Impact Factor -
Article: Novel LaBO3 hollow nanospheres of size 34±2 nm templated by polymeric micelles.
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ABSTRACT: Novel lanthanum borate (LaBO(3)) hollow nanospheres of size 34±2 nm have been reported for the first time by soft-template self-assembly process. Poly(styrene-b-acrylic acid-b-ethylene oxide) (PS-PAA-PEO) micelle with core-shell-corona architecture serves as an efficient soft template for fabrication of LaBO(3) hollow particles using sodium borohydride (NaBH(4)) and LaCl(3)⋅7H(2)O as the precursors. In this template, the PS block (core) acts as a template of the void space of hollow particle, the anionic PAA block (shell) serves as reaction field for metal ion interactions, and the PEO block (corona) stabilizes the polymer/lanthana composite particles. The PS-PAA-PEO micelles and the resulting LaBO(3) hollow nanospheres were thoroughly characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), X-ray diffraction, magic angle spinning-nuclear magnetic resonance ((11)B MAS NMR), energy dispersive X-ray analysis, thermal analyses, Fourier transform infra red spectroscopy, and nitrogen adsorption/desorption analyses. The nitrogen adsorption/desorption analyses and TEM observation of the hollow particles confirmed the presence of disordered mesopores in the LaBO(3) shell domain. The solid state (11)B MAS NMR spectra of LaBO(3) hollow nanospheres revealed that the shell part contains both trigonal and tetrahedral boron species. The LaBO(3) hollow particles were applied to anode materials in lithium-ion rechargeable batteries (LIBs). The hollow particles exhibited high coulombic efficiency and charge-discharge cycling capacities of up to 100 cycles in the LIBs.Journal of Colloid and Interface Science 03/2012; 370(1):51-7. · 3.07 Impact Factor -
Article: WO3hollownanospheres for high-lithiumstoragecapacity and goodcyclability
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ABSTRACT: WO3hollow nanosphere is reported using polymeric micelle with core–shell–corona architecture. Poly(styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride-b-ethylene oxide) micelles (PS-PMAPTAC-PEO) with cationic shell block facilitates the self-assembly of hollow particles through electrostatic interaction with anionic WO42− precursors. X-ray diffraction (XRD) analysis confirmed the formation of pure WO3 with hexagonal lattice-structure. Transmission electron microscope (TEM) image of WO3 has confirmed the hollow structure with average outer diameter of 42±2; the hollow cavity diameter was found to be 21±1 nm. The WO3hollownanospheres were investigated as anode materials for lithium ion battery. The nanostructured electrode delivers high initial discharge capacity of 1054 mA h g−1 at a charge/discharge 0.2 C. Interestingly, the hollow particles based electrodes maintain the structural integrity even after been subjected to high current density 2000 A g−1 and electrode stability.Nano Energy. 03/2012; 1(3):503. -
Article: V2O5 Hollow Nanospheres: A Lithium Intercalation Host with Good Rate Capability and Capacity Retention
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ABSTRACT: V2O5 hollow nanospheres of average diameter ca. ~28 nm and hollow cavity size ca. 18 nm were prepared by using polymeric micelles as a soft template. Transmission electron microscope (TEM) and X-ray diffraction (XRD) analyzes have confirmed the hollow spherical morphology with crystalline shell structure. The V2O5 hollow particles were investigated as cathode materials for lithium intercalation in Li-ion batteries (LIBs). The nanostructured electrode delivers a high capacity of 181 mAhg−1 with capacity retention of 92.6% after 50 cycles of charge/discharge at a rate of 0.5 C. Interestingly, the hollow particles based electrodes maintain the structural integrity even after subjecting to high current density 2000 Ag−1 (10 C) and show good cycling performance and electrode stability. The enhanced electrochemical behavior is attributed to nanosize effect coupled with hollow void space of V2O5 hollow particles that facilitates fast lithium intercalation/deintercalation.Journal of The Electrochemical Society 03/2012; 159:A618. · 2.59 Impact Factor -
Article: La2O3 hollow nanospheres for high performance lithium-ion rechargeable batteries.
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ABSTRACT: An efficient and simple protocol for synthesis of novel La(2)O(3) hollow nanospheres of size about 30 ± 2 nm using polymeric micelles is reported. The La(2)O(3) hollow nanospheres exhibit high charge capacity and cycling performance in lithium-ion rechargeable batteries (LIBs), which was scrutinized for the first time among the rare-earth oxides.Chemical Communications 02/2012; 48(26):3200-2. · 6.17 Impact Factor -
Article: The study of electrochemical properties and lithium deposition of graphite at low temperature
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ABSTRACT: Graphite samples with different amount of graphitization, rhombohedral phase, particle shapes and surface area are electrochemically investigated at 25 oC and -5 oC. It was found that the degree of graphitization and the amount of rhombohedral phase in graphite play an important role for the lithium intercalation/deintercalation and amount of lithium deposition on the graphite samples. Due to low conductivity of electrolyte and slow diffusion of lithium ions into the graphite interlayers, the charge/discharge capacity of graphite sample was found to be significantly low at -5 oC. In addition, lithium deposition occurs on graphite at -5 oC. The graphite samples with high graphitization can easily affect by ambient temperatures, which shows a reduced capacity at low temperatures. The graphite with high rhombohedral phase shows high lithium deposition on the graphite surface, because lithium ion does not diffuse into the interlayer of graphites and accumulates at the edge plane of graphite. Increasing pathway for lithium ion intercalation into the graphite could help accelerating lithium intercalation and decreasing amounts of lithium deposition on the graphite.Journal of Power Sources 01/2012; 199:293. · 4.95 Impact Factor -
Article: The study of electrochemical properties and lithium deposition of graphite at low temperature
Journal of Power Sources 01/2012; 199:293. · 4.95 Impact Factor -
Article: Periodic organosilica hollow nanospheres as anode materials for lithium ion rechargeable batteries.
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ABSTRACT: Polymeric micelles with core-shell-corona architecture have been found to be the efficient colloidal templates for synthesis of periodic organosilica hollow nanospheres over a broad pH range from acidic to alkaline media. In alkaline medium, poly (styrene-b-[3-(methacryloylamino)propyl] trimethylammonium chloride-b-ethylene oxide) (PS-PMAPTAC-PEO) micelles yield benzene-silica hollow nanospheres with molecular scale periodicity of benzene groups in the shell domain of hollow particles. Whereas, an acidic medium (pH 4) produces diverse hollow particles with benzene, ethylene, and a mixture of ethylene and dipropyldisulfide bridging functionalities using poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-PVP-PEO) micelles. These hollow particles were thoroughly characterized by powder X-ray diffraction (XRD), dynamic light scattering (DLS), thermogravimetric analysis (TG/DTA), Fourier transformation infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), magic angle spinning-nuclear magnetic resonance ((29)Si MAS NMR and (13)CP-MAS NMR), Raman spectroscopy, and nitrogen adsorption/desorption analyses. The benzene-silica hollow nanospheres with molecular scale periodicity in the shell domain exhibit higher cycling performance of up to 300 cycles in lithium ion rechargeable batteries compared with micron-sized dense benzene-silica particles.Nanoscale 11/2011; 3(11):4768-73. · 5.91 Impact Factor -
Article: Novel titania hollow nanospheres of size 28 ± 1 nm using soft-templates and their application for lithium-ion rechargeable batteries.
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ABSTRACT: We report a novel protocol to prepare titania hollow nanospheres of size about 28 ± 1 nm with micelles of asymmetric triblock copolymers. The hollow particles exhibit unique electrochemical properties in lithium ion rechargeable batteries such as high capacity, very low irreversible capacity loss, and high cycling performance.Chemical Communications 06/2011; 47(24):6921-3. · 6.17 Impact Factor -
Article: Suppression of lithium deposition at sub-zero temperatures on the graphite by surface modification
Electrochemistry Communications 01/2011; 13:1116. · 4.86 Impact Factor -
Article: Novel LaBO3 Hollow Nanospheres of Size 34±2 nm Templated by Polymeric Micelles
Journal of Colloid and Interface Science 01/2011; · 3.07 Impact Factor -
Article: Suppression of Li deposition on surface of graphite using carbon coating by thermal vapor deposition process
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ABSTRACT: 10 wt.% carbon-coated natural graphite (NC-10) is prepared by thermal vapor deposition. The carbon coating is electrochemically investigated at -5 °C; it improves lithium intercalation in the graphite’s interlayer spacing. NC-10 graphite clearly shows three voltage plateaus and a higher capacity during the first charge/discharge cycle at -5 °C than uncoated natural graphite. XRD study of the electrode after the first charging shows increased lithium intercalation into the graphite layers and also suppression of lithium deposition on the graphite’s surface. Due to the homogeneous potential profile on the graphite surface, carbon coating enhance lithium intercalation at -5 °C. In addition, NC-10 shows less lithium deposition on the surface than bare natural graphite.journal of power sources. 01/2011; 196:9820. -
Article: Synthesis, characterization and application for lithium-ion rechargeable batteries of hollow silica nanospheres
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ABSTRACT: Hollow silica nanospheres with uniform size of about 30 nm have been successfully synthesized using a template of ABC triblock copolymer micelles of poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS–PVP–PEO) with a core–shell–corona architecture. In this type of triblock copolymers, the PS block (core) works as a template of the void space of hollow silica, the PVP block (shell) acts as a reaction field for the sol–gel reaction of tetramethoxysilane (TMOS), and the PEO block (corona) stabilizes the polymer/silica composite particles. Use of polymers with different chain lengths of PS, PVP, and PEO led to hollow silica with tunable cavity size and wall thickness. The obtained hollow particles were thoroughly characterized by X-ray diffraction (XRD), thermal (TG/DTA) and nitrogen sorption analyses, infra-red (FT IR) and nuclear magnetic resonance (29Si MAS NMR) spectroscopies, and transmission electron microscopy (TEM). The efficiency of hollow silica nanospheres for lithium-ion rechargeable batteries is demonstrated for the first time. The hollow silica nanoparticles exhibited high cycle performance of up to 500 cycles in the lithium rechargeable batteries through the alloying/dealloying process. The tiny grain size of hollow nanospheres results in less volume expansion and/or contraction during charge/discharge cycles.Journal of material chemistry. 01/2011; 21:13881. -
Article: Constructing a novel and safer energy storing system using a graphite cathode and a MoO3 anode
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ABSTRACT: A cell employing a graphite cathode and a molybdenum (VI) oxide (MoO3) anode is investigated as a possible energy storage device. Graphite cathode allows raising the voltage well above the cathode materials of LIBs without causing safety issues. The bottom potential of this anode is 2.0 V vs. Li/Li+, which is well above the lithium plating potential. Pulse polarization experiment reveals that no lithium deposition occurs, which further enhances the safety of the graphite/MoO3 full cell. Charge/discharge mechanism of this system results from intercalation and de-intercalation of the PF6− in the cathode (KS-6) and Li+ in the anode (MoO3). This mechanism is supported by in situ X-ray diffraction data of the graphite/MoO3 cell recorded at various states of charge.Journal of Power Sources. 01/2011; 2011:7896. -
Article: Performance of a Graphite (KS-6)/MoO3 Energy Storing System
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ABSTRACT: The performance of the graphite (KS-6)/MoO3 full cell has been studied at different cut-off voltages, rates, temperatures, cathode to anode mass ratios. It was found that cathode to anode weight ratio and charging potential are the most influential parameters which determine the cycle life of this device. Under optimized condition (graphite:MoO3 weight ratio 1 and operation voltage window 1.5-3.3 V), the capacity retention of the cell between the 5th and 500th cycles was found to be 91%. At 0.3 C and 10 C rates this device delivers 88.9 mAh.g-1 and 35.5 mAhg-1, respectively. High and low temperature performance of this device is superior to that of the conventional EDLCs. The charge/discharge mechanism of the full cell was elucidated by ex-situ XRD data and analyzing the voltage profiles of each electrode by 4-electrode cell. Partial amorphization of the MoO3 anode was confirmed by XRD and SEM data. These results indicate that the electrolyte could be used as the sole source of lithium ions to develop a novel type of energy storage devices which do not contain traditional lithium rich cathode materials.Journal of Power Sources 01/2011; · 4.95 Impact Factor -
Article: Syhthesis, characterization and application for lithium-ion rechargeable batteries of hollow silica nanospheres
Journal of Materials Chemistry 01/2011; 21:13888. · 5.97 Impact Factor -
Article: Suppression of Li deposition on surface of graphite using carbon coating by thermal vapor deposition process
Journal of Power Sources 01/2011; 196:9820. · 4.95 Impact Factor
Top co-authors
Top Journals
Institutions
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1996–2012
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Saga University
- • Faculty of Sciences & Engineering
- • Department of Chemistry and Applied Chemistry
Saga-shi, Saga-ken, Japan
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2010
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Chinese Academy of Sciences
Beijing, Beijing Shi, China
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2002
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Hanyang University
Ansan, Gyeonggi, South Korea
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