The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hee-tak Kim - One of the best experts on this subject based on the ideXlab platform.
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Sustainable Redox Mediation for Lithium-Oxygen Batteries by a Composite Protective Layer on the Lithium-Metal Anode
Advanced Materials, 2016Co-Authors: Dong-jin Lee, Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Hee-tak KimAbstract:A synergic combination of a soluble -redox mediator and a protected Li metal -electrode to prevent the self-discharge of the redox mediator is realized by -exploiting a 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) redox mediator and an Al2 O3 /PVdF-HFP composite -Protective Layer (CPL). Stabilization of Li metal by simple CPL coating is effective at -suppressing the chemical reduction of the oxidized TEMPO and opens up the possibility of sustainable redox mediation for robust cycling of Li-O2 batteries.
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a simple composite Protective Layer coating that enhances the cycling stability of lithium metal batteries
Journal of Power Sources, 2015Co-Authors: Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Dong-jin Lee, Hee-tak KimAbstract:Abstract Metallic lithium is the most promising negative electrode for high-energy rechargeable batteries due to its extremely high specific capacity and its extremely low redox potential. However, the low cycle efficiency and lithium dendrite formation during the charge/discharge processes consistently hinder its practical application. In this report, we present a stabilized Li electrode on which a Li + ion conductive inorganic/organic composite Protective Layer (CPL) is coated. With the introduction of the CPL, the Li dendrite growth and electrolyte decomposition are effectively suppressed; consequently, stable Li plating/stripping at high current densities up to 10 mA cm −2 is possible. Nanoindentation tests demonstrate that the shear modulus of the CPL at narrow indentations is 1.8 times higher than that of the Li metal, which provides a theoretical understanding for its efficacy. Moreover, the LiCoO 2 /Li cell incorporating CPL exhibits excellent cycling stability up to 400 cycles at 1 mA cm −2 (1 C-rate), which demonstrates practical applicability in Li ion batteries through replacing the graphite anode with a CPL-coated Li metal anode.
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composite Protective Layer for li metal anode in high performance lithium oxygen batteries
Electrochemistry Communications, 2014Co-Authors: Dong-jin Lee, Hee-tak Kim, Hongkyung Lee, Jongchan Song, Myunghyun Ryou, Yong Min Lee, Jung-ki ParkAbstract:Abstract Lithium–oxygen batteries are of great interest because of their very high-energy density; however, they present many challenges, one of which is the low cycling stability of a lithium (Li) metal anode. Here, we report a composite Protective Layer (CPL) comprising Al 2 O 3 and polyvinylidene fluoride-hexafluoro propylene for a Li metal anode that resulted in a dramatic enhancement of the cycling stability of a lithium–oxygen battery. A cell with the CPL-coated Li metal anode exhibited more than 3 times higher discharge capacity at the 80th cycle compared to a cell without the CPL. X-ray photoelectron spectroscopy measurements for the cycled lithium metal anodes confirm that the CPL effectively suppressed electrolyte decomposition at the surface of the Li metal anode.
Jung-ki Park - One of the best experts on this subject based on the ideXlab platform.
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Sustainable Redox Mediation for Lithium-Oxygen Batteries by a Composite Protective Layer on the Lithium-Metal Anode
Advanced Materials, 2016Co-Authors: Dong-jin Lee, Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Hee-tak KimAbstract:A synergic combination of a soluble -redox mediator and a protected Li metal -electrode to prevent the self-discharge of the redox mediator is realized by -exploiting a 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) redox mediator and an Al2 O3 /PVdF-HFP composite -Protective Layer (CPL). Stabilization of Li metal by simple CPL coating is effective at -suppressing the chemical reduction of the oxidized TEMPO and opens up the possibility of sustainable redox mediation for robust cycling of Li-O2 batteries.
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a simple composite Protective Layer coating that enhances the cycling stability of lithium metal batteries
Journal of Power Sources, 2015Co-Authors: Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Dong-jin Lee, Hee-tak KimAbstract:Abstract Metallic lithium is the most promising negative electrode for high-energy rechargeable batteries due to its extremely high specific capacity and its extremely low redox potential. However, the low cycle efficiency and lithium dendrite formation during the charge/discharge processes consistently hinder its practical application. In this report, we present a stabilized Li electrode on which a Li + ion conductive inorganic/organic composite Protective Layer (CPL) is coated. With the introduction of the CPL, the Li dendrite growth and electrolyte decomposition are effectively suppressed; consequently, stable Li plating/stripping at high current densities up to 10 mA cm −2 is possible. Nanoindentation tests demonstrate that the shear modulus of the CPL at narrow indentations is 1.8 times higher than that of the Li metal, which provides a theoretical understanding for its efficacy. Moreover, the LiCoO 2 /Li cell incorporating CPL exhibits excellent cycling stability up to 400 cycles at 1 mA cm −2 (1 C-rate), which demonstrates practical applicability in Li ion batteries through replacing the graphite anode with a CPL-coated Li metal anode.
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composite Protective Layer for li metal anode in high performance lithium oxygen batteries
Electrochemistry Communications, 2014Co-Authors: Dong-jin Lee, Hee-tak Kim, Hongkyung Lee, Jongchan Song, Myunghyun Ryou, Yong Min Lee, Jung-ki ParkAbstract:Abstract Lithium–oxygen batteries are of great interest because of their very high-energy density; however, they present many challenges, one of which is the low cycling stability of a lithium (Li) metal anode. Here, we report a composite Protective Layer (CPL) comprising Al 2 O 3 and polyvinylidene fluoride-hexafluoro propylene for a Li metal anode that resulted in a dramatic enhancement of the cycling stability of a lithium–oxygen battery. A cell with the CPL-coated Li metal anode exhibited more than 3 times higher discharge capacity at the 80th cycle compared to a cell without the CPL. X-ray photoelectron spectroscopy measurements for the cycled lithium metal anodes confirm that the CPL effectively suppressed electrolyte decomposition at the surface of the Li metal anode.
Dong-jin Lee - One of the best experts on this subject based on the ideXlab platform.
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Sustainable Redox Mediation for Lithium-Oxygen Batteries by a Composite Protective Layer on the Lithium-Metal Anode
Advanced Materials, 2016Co-Authors: Dong-jin Lee, Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Hee-tak KimAbstract:A synergic combination of a soluble -redox mediator and a protected Li metal -electrode to prevent the self-discharge of the redox mediator is realized by -exploiting a 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) redox mediator and an Al2 O3 /PVdF-HFP composite -Protective Layer (CPL). Stabilization of Li metal by simple CPL coating is effective at -suppressing the chemical reduction of the oxidized TEMPO and opens up the possibility of sustainable redox mediation for robust cycling of Li-O2 batteries.
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a simple composite Protective Layer coating that enhances the cycling stability of lithium metal batteries
Journal of Power Sources, 2015Co-Authors: Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Dong-jin Lee, Hee-tak KimAbstract:Abstract Metallic lithium is the most promising negative electrode for high-energy rechargeable batteries due to its extremely high specific capacity and its extremely low redox potential. However, the low cycle efficiency and lithium dendrite formation during the charge/discharge processes consistently hinder its practical application. In this report, we present a stabilized Li electrode on which a Li + ion conductive inorganic/organic composite Protective Layer (CPL) is coated. With the introduction of the CPL, the Li dendrite growth and electrolyte decomposition are effectively suppressed; consequently, stable Li plating/stripping at high current densities up to 10 mA cm −2 is possible. Nanoindentation tests demonstrate that the shear modulus of the CPL at narrow indentations is 1.8 times higher than that of the Li metal, which provides a theoretical understanding for its efficacy. Moreover, the LiCoO 2 /Li cell incorporating CPL exhibits excellent cycling stability up to 400 cycles at 1 mA cm −2 (1 C-rate), which demonstrates practical applicability in Li ion batteries through replacing the graphite anode with a CPL-coated Li metal anode.
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composite Protective Layer for li metal anode in high performance lithium oxygen batteries
Electrochemistry Communications, 2014Co-Authors: Dong-jin Lee, Hee-tak Kim, Hongkyung Lee, Jongchan Song, Myunghyun Ryou, Yong Min Lee, Jung-ki ParkAbstract:Abstract Lithium–oxygen batteries are of great interest because of their very high-energy density; however, they present many challenges, one of which is the low cycling stability of a lithium (Li) metal anode. Here, we report a composite Protective Layer (CPL) comprising Al 2 O 3 and polyvinylidene fluoride-hexafluoro propylene for a Li metal anode that resulted in a dramatic enhancement of the cycling stability of a lithium–oxygen battery. A cell with the CPL-coated Li metal anode exhibited more than 3 times higher discharge capacity at the 80th cycle compared to a cell without the CPL. X-ray photoelectron spectroscopy measurements for the cycled lithium metal anodes confirm that the CPL effectively suppressed electrolyte decomposition at the surface of the Li metal anode.
Hongkyung Lee - One of the best experts on this subject based on the ideXlab platform.
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Sustainable Redox Mediation for Lithium-Oxygen Batteries by a Composite Protective Layer on the Lithium-Metal Anode
Advanced Materials, 2016Co-Authors: Dong-jin Lee, Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Hee-tak KimAbstract:A synergic combination of a soluble -redox mediator and a protected Li metal -electrode to prevent the self-discharge of the redox mediator is realized by -exploiting a 2,2,6,6-tetramethylpiperidinyl 1-oxyl (TEMPO) redox mediator and an Al2 O3 /PVdF-HFP composite -Protective Layer (CPL). Stabilization of Li metal by simple CPL coating is effective at -suppressing the chemical reduction of the oxidized TEMPO and opens up the possibility of sustainable redox mediation for robust cycling of Li-O2 batteries.
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a simple composite Protective Layer coating that enhances the cycling stability of lithium metal batteries
Journal of Power Sources, 2015Co-Authors: Hongkyung Lee, Yun Jung Kim, Jung-ki Park, Dong-jin Lee, Hee-tak KimAbstract:Abstract Metallic lithium is the most promising negative electrode for high-energy rechargeable batteries due to its extremely high specific capacity and its extremely low redox potential. However, the low cycle efficiency and lithium dendrite formation during the charge/discharge processes consistently hinder its practical application. In this report, we present a stabilized Li electrode on which a Li + ion conductive inorganic/organic composite Protective Layer (CPL) is coated. With the introduction of the CPL, the Li dendrite growth and electrolyte decomposition are effectively suppressed; consequently, stable Li plating/stripping at high current densities up to 10 mA cm −2 is possible. Nanoindentation tests demonstrate that the shear modulus of the CPL at narrow indentations is 1.8 times higher than that of the Li metal, which provides a theoretical understanding for its efficacy. Moreover, the LiCoO 2 /Li cell incorporating CPL exhibits excellent cycling stability up to 400 cycles at 1 mA cm −2 (1 C-rate), which demonstrates practical applicability in Li ion batteries through replacing the graphite anode with a CPL-coated Li metal anode.
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composite Protective Layer for li metal anode in high performance lithium oxygen batteries
Electrochemistry Communications, 2014Co-Authors: Dong-jin Lee, Hee-tak Kim, Hongkyung Lee, Jongchan Song, Myunghyun Ryou, Yong Min Lee, Jung-ki ParkAbstract:Abstract Lithium–oxygen batteries are of great interest because of their very high-energy density; however, they present many challenges, one of which is the low cycling stability of a lithium (Li) metal anode. Here, we report a composite Protective Layer (CPL) comprising Al 2 O 3 and polyvinylidene fluoride-hexafluoro propylene for a Li metal anode that resulted in a dramatic enhancement of the cycling stability of a lithium–oxygen battery. A cell with the CPL-coated Li metal anode exhibited more than 3 times higher discharge capacity at the 80th cycle compared to a cell without the CPL. X-ray photoelectron spectroscopy measurements for the cycled lithium metal anodes confirm that the CPL effectively suppressed electrolyte decomposition at the surface of the Li metal anode.
Eun Ha Choi - One of the best experts on this subject based on the ideXlab platform.
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secondary electron emission from mgo Protective Layer by auger neutralization of ions
Applied Physics Letters, 2009Co-Authors: Han S Uhm, Eun Ha Choi, Guang S ChoAbstract:A theoretical model of the secondary electron emission yield (γ) from a MgO Layer is developed based on the Auger neutralization of ions, resulting in an analytical expression of γ in terms of the ionization energy Ei for the density of states in the valence band, being an exponentially decaying function of the energy deviation from the band characteristic energy of 7.88 eV. The analytical expression recovers the previously known empirical formulation of γ∼(Ei−2φ) for the work function φ. Results of the theoretical model agree well with the measured data in terms of the data trend.
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characteristics of secondary electron emission coefficient and sputtering yield for mgal2o4 mgo Protective Layer in ac plasma display panels
Japanese Journal of Applied Physics, 2006Co-Authors: Jinman Jeoung, Seung Oun Kang, Hyejung Lee, Yongwhan Jung, Kangwon Jung, Eun Ha ChoiAbstract:The secondary electron emission coefficient (γ) and sputtering yield of the MgAl2O4/MgO Protective Layer has been investigated using γ-focused ion beam (γ-FIB) and focused ion beam (FIB) systems, respectively. The MgAl2O4/MgO Protective Layer has higher γ values (from 0.09 to 0.12) than the single MgAl2O4 Protective Layer (from 0.06 to 0.07) at Ne+ ion energies ranging from 90 to 200 eV. Also it has been found that the secondary electron emission coefficient (γ) of the MgAl2O4/MgO Protective Layer is similar to that of the MgO Protective Layer. Moreover, the MgAl2O4/MgO Protective Layer has been found to have lower sputtering yields (from 0.25 to 0.35) than the MgO Protective Layer (from 0.36 to 0.44) for Ga+ ion energies ranging from 10 to 14 keV.
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ion induced secondary electron emission coefficient γ from mgo Protective Layer with microscopic surface structures in alternating current plasma display panels
Japanese Journal of Applied Physics, 2004Co-Authors: Eun Ha ChoiAbstract:We have investigated the influence of microscopic surface structures of the MgO Protective Layer on the ion-induced secondary electron emission coefficient in alternating-current plasma display panels (AC-PDPs). The microscopic surface structures of the MgO Protective Layer have been formed by using a mesh mask with an electron beam evaporation method. The ion-induced secondary electron emission coefficient γ of the MgO Protective Layer with mesh-patterned microscopic surface structures has been measured by the γ-FIB (focused ion beam) system. It is found that the MgO Protective Layer with microscopic surface structures has a higher γ than those without any surface structures.
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influence of vacuum annealing process on the secondary electron emission coefficient γ from a mgo Protective Layer
Japanese Journal of Applied Physics, 2001Co-Authors: Jinman Jeoung, Jae Yong Lim, Guangsup Cho, Young-guon Kim, Yoonho Seo, Eun Ha ChoiAbstract:The secondary electron emission coefficient (γ) of vacuum-annealed MgO films has been investigated using a γ-focused ion beam (γ-FIB) system. The vacuum-annealed MgO films have been found to have higher γ values from 0.05 to 0.12 than those from 0.03 to 0.06 for as-deposited MgO films for operating Ne+ ions whose acceleration voltages ranged from 50 V to 200 V. It is shown that the γ for the as-deposited MgO Protective Layer is significantly decreased by the influence of holding in air since the hydroxyl OH groups are absorbed onto the MgO surface from the atmospheric air. It is also observed that the secondary electron emission coefficient γ for the vacuum-annealed MgO Protective Layer is less influenced by holding in air than that for the as-deposited MgO Protective Layer. Based on these findings, it is concluded that the vacuum-annealed MgO Protective Layer plays an important role in lowering the firing voltage in alternating current-plasma display panel (AC-PDP) compared with the as-deposited MgO Protective Layer or the as-deposited MgO Protective Layer held in air.
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measurement of secondary electron emission coefficient γ of mgo Protective Layer with various crystallinities
Japanese Journal of Applied Physics, 1998Co-Authors: Eun Ha Choi, Jae Yong Lim, Guangsup Cho, Young-guon Kim, Daeil Kim, Jingoo Kim, Seung Oun KangAbstract:The secondary electron emission coefficient γ of a MgO Protective Layer with various crystallinities has been successfully measured by the γ-focused ion beam system with complete elimination of the charge accumulation problem by scanning-area adjustment techniques. It is found that the (111) surface has the highest γ from 0.14 to 0.26 in comparison with the other films with (200) and (220) crystallinities for operating Ne+ ions, while ranged from 0.03 to 0.24 for Ar+ ions, under operating ion energies from 50 eV to 500 eV throughout this experiment. These observations explain why the (111) crystallinity of the MgO Protective Layer plays an important role in lowering the firing voltages in AC plasma display panel compared to the films with other crystallinities.
