The Experts below are selected from a list of 1716 Experts worldwide ranked by ideXlab platform
Yungeun Sung - One of the best experts on this subject based on the ideXlab platform.
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Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator
'Springer Science and Business Media LLC', 2018Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li 2 S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g -1 cathode capacity after 50 cycles, which is equivalent to 800 mAh g -1 S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved. © The Author(s) 20165
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discharging a li s battery with ultra high sulphur content cathode using a redox mediator
Scientific Reports, 2016Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li2S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g−1cathode capacity after 50 cycles, which is equivalent to 800 mAh g−1S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.
Kwi Ryong Kim - One of the best experts on this subject based on the ideXlab platform.
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Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator
'Springer Science and Business Media LLC', 2018Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li 2 S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g -1 cathode capacity after 50 cycles, which is equivalent to 800 mAh g -1 S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved. © The Author(s) 20165
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discharging a li s battery with ultra high sulphur content cathode using a redox mediator
Scientific Reports, 2016Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li2S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g−1cathode capacity after 50 cycles, which is equivalent to 800 mAh g−1S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.
Baiquan Wang - One of the best experts on this subject based on the ideXlab platform.
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The exo-substituted η4-cyclopentadiene CpCo(I) complexes: A new kind of ATRP catalysts and the actual catalyst for the Cobaltocene-catalyzed ATRP
Polymer, 2009Co-Authors: Xiongxiong Luo, Xi Zhao, Baiquan WangAbstract:Abstract The exo-substituted η 4 -cyclopentadiene CpCo(I) complexes were found to be the actual catalyst for the Cobaltocene-catalyzed ATRP. Cobaltocene is just a precatalyst, which can be converted to the catalyst by the reaction with halide initiator. As a new kind of ATRP catalyst, the exo-substituted η 4 -cyclopentadiene CpCo(I) complexes can catalyze the living radical polymerization of MMA, styrene, and the block copolymerization of MMA with styrene.
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controlled living radical polymerization of styrene catalyzed by Cobaltocene
Polymer, 2008Co-Authors: Xiongxiong Luo, Xi Zhao, Yan Zhuang, Min Zhang, Baiquan WangAbstract:Abstract Controlled/living radical polymerization of styrene has been achieved by atom transfer radical polymerization (ATRP) catalyzed by Cobaltocene (PDI = 1.27–1.41). The effects of the initiators, temperatures and solvents were studied. The end group of PS–Br was characterized by 1 H NMR. Block copolymerization proved that the polymer end is still living and the PMMA- b -PSt block copolymer was synthesized.
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Controlled/living radical polymerization of styrene catalyzed by Cobaltocene
Polymer, 2008Co-Authors: Xiongxiong Luo, Xi Zhao, Yan Zhuang, Min Zhang, Baiquan WangAbstract:Abstract Controlled/living radical polymerization of styrene has been achieved by atom transfer radical polymerization (ATRP) catalyzed by Cobaltocene (PDI = 1.27–1.41). The effects of the initiators, temperatures and solvents were studied. The end group of PS–Br was characterized by 1 H NMR. Block copolymerization proved that the polymer end is still living and the PMMA- b -PSt block copolymer was synthesized.
J L Martinez - One of the best experts on this subject based on the ideXlab platform.
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x ray diffraction xps and magnetic properties of lanthanide based misfit layered sulfides intercalated with Cobaltocene
Chemistry of Materials, 2000Co-Authors: L Hernan, J Morales, L Sanchez, Jose Gameiro Dos Santos, Enrique Rodriguezcastellon, J L MartinezAbstract:Polycrystalline (CeS)1.15(TaS2)2 and (SmS)1.19(TaS2)2, two composite misfit-layered sulfides, react directly with Cobaltocene (CoCp2) in acetonitrile solutions to form novel intercalation compounds of composition (CeS)1.15(TaS2)2(CoCp2)0.31 and (SmS)1.19(TaS2)2(CoCp2)0.30, respectively. Their powder X-ray diffraction data reveal a significant expansion (ca.5.5 A) along the c-axis and preservation of the a-b-axis dimensions. One-dimensional electron density calculations are consistent with a model where the guest molecule is located at all TaS2-TaS2 interfaces, whereas MS-TaS2 (M ) Ce, Sm) interfaces remain empty. The Ce and Sm 3d core-level spectra reveal that these elements are present mainly as tervalent ions. The magnetic properties of the Ce compound are consistent with this valence state. Although the intercalation of Cobaltocene does not shift the binding energies of the host constituent elements appreciably, the organometallic molecule is intercalated as CoCp2 + ions, as is usually the case with layered chalcogenide hosts. In the case of the Ce system, this model is also supported by the magnetic data and suggests that the electron donated by the guest molecule is transferred to the conduction band of the TaS2 layers, whereas the lanthanide element remains as a trivalent ion. The formal electron transfer apparently taking place from the MS bilayer (M ) Ce, Sm) to TaS2 sheets does not prevent ionization of Cobaltocene.
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X-ray Diffraction, XPS, and Magnetic Properties of Lanthanide-Based Misfit-Layered Sulfides Intercalated with Cobaltocene
Chemistry of Materials, 2000Co-Authors: Lourdes Hernán, Julián Morales, Luis Sánchez, Jose Gameiro Dos Santos, Enrique Rodríguez-castellón, J L MartinezAbstract:Polycrystalline (CeS)1.15(TaS2)2 and (SmS)1.19(TaS2)2, two composite misfit-layered sulfides, react directly with Cobaltocene (CoCp2) in acetonitrile solutions to form novel intercalation compounds of composition (CeS)1.15(TaS2)2(CoCp2)0.31 and (SmS)1.19(TaS2)2(CoCp2)0.30, respectively. Their powder X-ray diffraction data reveal a significant expansion (ca.5.5 A) along the c-axis and preservation of the a−b-axis dimensions. One-dimensional electron density calculations are consistent with a model where the guest molecule is located at all TaS2-TaS2 interfaces, whereas MS−TaS2 (M = Ce, Sm) interfaces remain empty. The Ce and Sm 3d core-level spectra reveal that these elements are present mainly as tervalent ions. The magnetic properties of the Ce compound are consistent with this valence state. Although the intercalation of Cobaltocene does not shift the binding energies of the host constituent elements appreciably, the organometallic molecule is intercalated as CoCp2+ ions, as is usually the case with lay...
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electrical transport and magnetic properties of misfit layered compounds intercalated with Cobaltocene
Chemistry of Materials, 1999Co-Authors: J Morales, Jose Gameiro Dos Santos, Jacobus Baas, G A Wiegers, J L MartinezAbstract:The electrical and magnetic properties of misfit layered Cobaltocene complexes of composition (PbS)(1.18)(TiS2)(2)(CoCp2)(0.28), (PbS)(1.14)(TaS2)(2)(CoCp2)(0.28), and (PbSe)(1.12)(NbSe2)(2)(CoCp2)(0.27) [Cp = C5H5-] were investigated. All the pristine chalcogenides studied exhibit a metallic behavior and a magnetic susceptibility virtually independent of temperature. Moreover, the Ta and Nb compounds-the later impurified with NbSe2-undergo a superconducting transition at low temperatures (T-C <4 K). Upon Cobaltocene intercalation, the Ta and Nb systems behave similarly. The superconducting transition temperature changes very little and the metallic behavior is preserved: the susceptibility is temperature-independent, whereas the resistivity increases with increasing temperature. This is consistent with an electron transfer from the metallocene to the host. The Ti intercalate behaves markedly differently. Thus, the complex undergoes a metal semiconducting transition below 70 K, and the magnetic data are significantly temperature-dependent. This localized moment may be consistent with the minimum observed in the resistivity values. The good overlapping properties 4d and 5d orbitals relative to 3d orbitals may account for the delocalization of the electron donated by the guest to the conduction band of the host.
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Electrical transport and magnetic properties of misfit layered compounds intercalated with Cobaltocene
Chemistry of Materials, 1999Co-Authors: Julián Morales, Jose Gameiro Dos Santos, Jacobus Baas, G A Wiegers, J L MartinezAbstract:The electrical and magnetic properties of misfit layered Cobaltocene complexes of composition (PbS)(1.18)(TiS2)(2)(CoCp2)(0.28), (PbS)(1.14)(TaS2)(2)(CoCp2)(0.28), and (PbSe)(1.12)(NbSe2)(2)(CoCp2)(0.27) [Cp = C5H5-] were investigated. All the pristine chalcogenides studied exhibit a metallic behavior and a magnetic susceptibility virtually independent of temperature. Moreover, the Ta and Nb compounds-the later impurified with NbSe2-undergo a superconducting transition at low temperatures (T-C
Kugseung Lee - One of the best experts on this subject based on the ideXlab platform.
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Discharging a Li-S battery with ultra-high sulphur content cathode using a redox mediator
'Springer Science and Business Media LLC', 2018Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li 2 S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g -1 cathode capacity after 50 cycles, which is equivalent to 800 mAh g -1 S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved. © The Author(s) 20165
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discharging a li s battery with ultra high sulphur content cathode using a redox mediator
Scientific Reports, 2016Co-Authors: Kwi Ryong Kim, Kugseung Lee, Chiyeong Ahn, Yungeun SungAbstract:Lithium-sulphur batteries are under intense research due to the high specific capacity and low cost. However, several problems limit their commercialization. One of them is the insulating nature of sulphur, which necessitates a large amount of conductive agent and binder in the cathode, reducing the effective sulphur load as well as the energy density. Here we introduce a redox mediator, Cobaltocene, which acts as an electron transfer agent between the conductive surface and the polysulphides in the electrolyte. We confirmed that Cobaltocene could effectively convert polysulphides to Li2S using scanning electron microscope, X-ray absorption near-edge structure and in-situ X-ray diffraction studies. This redox mediator enabled excellent electrochemical performance in a cathode with ultra-high sulphur content (80 wt%). It delivered 400 mAh g−1cathode capacity after 50 cycles, which is equivalent to 800 mAh g−1S in a typical cathode with 50 wt% sulphur. Furthermore, the volumetric capacity was also dramatically improved.