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Kentaro Nakahara - One of the best experts on this subject based on the ideXlab platform.

  • Organic Radical battery approaching practical use
    ChemInform, 2011
    Co-Authors: Kentaro Nakahara, Kenichi Oyaizu, Hiroyuki Nishide
    Abstract:

    The electrochemical redox reactions of Organic polymers bearing robust unpaired electrons were investigated to determine the applicability of these polymers to rechargeable batteries. Such an “orga...

  • cationic polymerization of poly vinyl ether bearing a tempo Radical a new cathode active material for Organic Radical batteries
    Macromolecular Rapid Communications, 2007
    Co-Authors: Masahiro Suguro, Shigeyuki Iwasa, Yuki Kusachi, Yukiko Morioka, Kentaro Nakahara
    Abstract:

    PTVE was synthesized as a new active material for Organic Radical batteries. Cationic polymerization of a monomer bearing a TEMPO Radical moiety took place. The spin concentration of PTVE was estimated to be 2.75 × 10 21 spins · g -1 (100% spin per repeating unit). The PTVE is extremely stable; there is no decrease in spin concentration when storing PTVE samples for more than a year under aerobic conditions at room temperature. The redox potential of PTVE is 3.55 V (vs. Li/Li + ). A coin-type cell using a PTVE/VGCF composite electrode was also fabricated, and then performed charge/discharge measurements. The discharge capacity of PTVE is 114 mAh ·g -1 (84% of the theoretical value).

  • high rate capable Organic Radical cathodes for lithium rechargeable batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) is the most common active material with a stable Radical molecular structure used for lithium rechargeable cells. Because it is an Organic active material, PTMA can be dissolved easily in various solvents. Using a solution of active material in the electrode making process, we formed an extremely large surface area between the active material and the conducting additive. The electrode has excellent power capability and can be charged and discharged in 1 min. We believe that this cell can be used like an electric double layer capacitor. We also believe that the cell, whose cycle life is good, retaining 89% of original capacity after 1000 cycles, can be put into practical use.

  • cell properties for modified ptma cathodes of Organic Radical batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Stable nitroxyl Radical polymers, such as poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA), are known to be effective as cathode active materials for lithium rechargeable batteries. A water-based slurry was used to prepare PTMA composite electrodes, enabling successful production of homogeneous electrodes. This improved utilization of active material and enabled us to obtain specific capacities almost equal to the theoretical value (111 mAh g−1). Lithium half cells were fabricated using these electrodes and using graphite as the anode active material, and their cycling stability, temperature dependence, rate capability and self-discharge rate were measured in detail. Although they showed 24% irreversible capacity on the first cycle, the capacity stabilized after the second cycle.

  • Al-laminated film packaged Organic Radical battery for high-power applications
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    A 100-mAh class of aluminum-laminated film packaged Organic Radical battery with a poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) composite cathode and a graphite anode has been fabricated. Its total weight was 22 g and the thickness was 4.3 mm. Because PTMA comprised only 6.2% of the total cell weight, the energy density was considerably less than that of a lithium ion battery. However, the power density per active material weight was found to be better than that of lithium ion battery. The applications which require high-power capability rather than high-energy density, such as the sub-battery in electronic devices and motor drive assistance in electric vehicles, would be appropriate for Organic Radical batteries in the future.

Kunio Awaga - One of the best experts on this subject based on the ideXlab platform.

  • photoinduced phase transition in an Organic Radical crystal with room temperature optical and magnetic bistability
    Physical Review Letters, 2003
    Co-Authors: Hiroyuki Matsuzaki, Wataru Fujita, Kunio Awaga, Hiroshi Okamoto
    Abstract:

    A phase control by photoirradiation is successfully achieved in a spin-Peierls system of the Organic Radical crystal, 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA), which exhibits optical and magnetic bistability around room temperature with a large hysteresis loop. A nanosecond laser pulse is found to induce a transition from a diamagnetic low-temperature phase to a paramagnetic high-temperature phase both inside (296 K) and outside (11 K) the hysteresis loop. Comparison of the excitation energy dependence between transition efficiency and photoconductivity suggests that the photoinduced transition is driven by suppression of the spin-Peierls instability by the accumulation of photocarriers.

  • Intercalation of stable Organic Radicals into layered copper hydroxides
    Synthetic Metals, 2001
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    Abstract We report the intercalation of a stable Organic Radical, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidine-1-oxyl anion (PROXYL − ) into the layered copper hydroxides, Cu 2 (OH) 3 (CH 3 CO 2 )·H 2 O, by means of the anion exchange. The powder X-ray diffractions reveal the anion exchange, showing an increase in the interlayer distance. However, the elemental analyses indicate that the obtained material is Cu 2 (OH) 3.5 (PROXYL) 0.5 ·H 2 O. The temperature dependence of the magnetic susceptibilities for the intercalation compound indicates a dominant antiferromagnetic interaction in contrast to the intralayer ferromagnetic interaction in the parent compound. The EPR spectra of the intercalation compound consist of the absorption of the Organic Radical, whose temperature-variable follows the Curie law. The observed antiferromagnetic properties can be ascribed to a transition in the magnetic properties of the [Cu 2 (OH) 3 ] + layer from ferromagnetic to antiferromagnetic upon intercalation.

  • Paramagnetic-diamagnetic phase transitions in Organic Radical crystals
    Synthetic Metals, 2001
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    A large first-order magnetic phase transition in an Organic Radical, 1,3,5-trithia-2,4,6-triazapentalenyl is described, that occurs with a wide thermal hysteresis loop over the temperature range from 230 to 305 K. The high-temperature phase is paramagnetic, while the low-temperature phase is diamagnetic. The results reported here on room-temperature magnetic molecular bistability may have applications in thermal sensors, switching units and information storage media, based on Organic Radical crystals.

  • Preparation and magnetic properties of saponite clays intercalated with stable Organic Radicals
    Journal of the Chemical Society Chemical Communications, 1995
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    The Organic Radical cations, 2-(3- and 4-N-methylpyridinium)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl 3-N-oxide, are intercalated into saponite clay {Na0.46[Si3.54Al0.46Mg3O10(OH)2]·nH2O} by means of cation exchange, and display Curie paramagnetic behaviour in the interlayers.

  • Intercalation of Pyridinium Nitronyl Nitroxides into the Saponite Clay Interlayers
    Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals, 1995
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    Abstract The N-alkylpyridinium nitronyl nitroxide cations were intercalated into saponite clay (Na0.46[Si3.54Al0.46Mg3O10(OH)2]nH2O) by means of the cation exchange. Up to 70 % of the sodium ions were replaced by the Organic Radicals. The Organic Radical-saponite nanocomposites were found to show Curie paramagnetic behavior.

Shigeyuki Iwasa - One of the best experts on this subject based on the ideXlab platform.

  • IMPACT TEST OF Organic Radical SECONDARY BATTERY
    2011
    Co-Authors: M. Ozaki, Shigeyuki Iwasa, Y. Aizawa, K. Tomura, K. Nakano
    Abstract:

    The Organic Radical Battery (ORB) utilizes charge storable plastics as an electrode active material, and charges and discharges by redox of those plastics. It has several advantages, i.e. very high power density, relatively high energy density, fast charge time, good charge-discharge cycleability and flexibility. Fuse Impact Simulator (FIS) with Firing Acceleration Simulator (FAS) can simulate variety of high-impact condition by launching the object inside the launcher using high pressure. The impact resistance of ORB is tested by using FIS and FAS. The ORB shows no degradation by the impact of 14,000–16,000 G in vertical direction when the sample is flat or the low impact of 7,000–8,000 G in horizontal direction when the sample is curved tightly. By sandwiching or bending the sample to support the structure, and improving the welded bond between the lead and the current collector, the ORB has potential to be used for ammunition.

  • cationic polymerization of poly vinyl ether bearing a tempo Radical a new cathode active material for Organic Radical batteries
    Macromolecular Rapid Communications, 2007
    Co-Authors: Masahiro Suguro, Shigeyuki Iwasa, Yuki Kusachi, Yukiko Morioka, Kentaro Nakahara
    Abstract:

    PTVE was synthesized as a new active material for Organic Radical batteries. Cationic polymerization of a monomer bearing a TEMPO Radical moiety took place. The spin concentration of PTVE was estimated to be 2.75 × 10 21 spins · g -1 (100% spin per repeating unit). The PTVE is extremely stable; there is no decrease in spin concentration when storing PTVE samples for more than a year under aerobic conditions at room temperature. The redox potential of PTVE is 3.55 V (vs. Li/Li + ). A coin-type cell using a PTVE/VGCF composite electrode was also fabricated, and then performed charge/discharge measurements. The discharge capacity of PTVE is 114 mAh ·g -1 (84% of the theoretical value).

  • high rate capable Organic Radical cathodes for lithium rechargeable batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) is the most common active material with a stable Radical molecular structure used for lithium rechargeable cells. Because it is an Organic active material, PTMA can be dissolved easily in various solvents. Using a solution of active material in the electrode making process, we formed an extremely large surface area between the active material and the conducting additive. The electrode has excellent power capability and can be charged and discharged in 1 min. We believe that this cell can be used like an electric double layer capacitor. We also believe that the cell, whose cycle life is good, retaining 89% of original capacity after 1000 cycles, can be put into practical use.

  • cell properties for modified ptma cathodes of Organic Radical batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Stable nitroxyl Radical polymers, such as poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA), are known to be effective as cathode active materials for lithium rechargeable batteries. A water-based slurry was used to prepare PTMA composite electrodes, enabling successful production of homogeneous electrodes. This improved utilization of active material and enabled us to obtain specific capacities almost equal to the theoretical value (111 mAh g−1). Lithium half cells were fabricated using these electrodes and using graphite as the anode active material, and their cycling stability, temperature dependence, rate capability and self-discharge rate were measured in detail. Although they showed 24% irreversible capacity on the first cycle, the capacity stabilized after the second cycle.

  • Al-laminated film packaged Organic Radical battery for high-power applications
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    A 100-mAh class of aluminum-laminated film packaged Organic Radical battery with a poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) composite cathode and a graphite anode has been fabricated. Its total weight was 22 g and the thickness was 4.3 mm. Because PTMA comprised only 6.2% of the total cell weight, the energy density was considerably less than that of a lithium ion battery. However, the power density per active material weight was found to be better than that of lithium ion battery. The applications which require high-power capability rather than high-energy density, such as the sub-battery in electronic devices and motor drive assistance in electric vehicles, would be appropriate for Organic Radical batteries in the future.

Masaharu Satoh - One of the best experts on this subject based on the ideXlab platform.

  • high rate capable Organic Radical cathodes for lithium rechargeable batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) is the most common active material with a stable Radical molecular structure used for lithium rechargeable cells. Because it is an Organic active material, PTMA can be dissolved easily in various solvents. Using a solution of active material in the electrode making process, we formed an extremely large surface area between the active material and the conducting additive. The electrode has excellent power capability and can be charged and discharged in 1 min. We believe that this cell can be used like an electric double layer capacitor. We also believe that the cell, whose cycle life is good, retaining 89% of original capacity after 1000 cycles, can be put into practical use.

  • cell properties for modified ptma cathodes of Organic Radical batteries
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    Abstract Stable nitroxyl Radical polymers, such as poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA), are known to be effective as cathode active materials for lithium rechargeable batteries. A water-based slurry was used to prepare PTMA composite electrodes, enabling successful production of homogeneous electrodes. This improved utilization of active material and enabled us to obtain specific capacities almost equal to the theoretical value (111 mAh g−1). Lithium half cells were fabricated using these electrodes and using graphite as the anode active material, and their cycling stability, temperature dependence, rate capability and self-discharge rate were measured in detail. Although they showed 24% irreversible capacity on the first cycle, the capacity stabilized after the second cycle.

  • Al-laminated film packaged Organic Radical battery for high-power applications
    Journal of Power Sources, 2007
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh, Elton J. Cairns
    Abstract:

    A 100-mAh class of aluminum-laminated film packaged Organic Radical battery with a poly(2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA) composite cathode and a graphite anode has been fabricated. Its total weight was 22 g and the thickness was 4.3 mm. Because PTMA comprised only 6.2% of the total cell weight, the energy density was considerably less than that of a lithium ion battery. However, the power density per active material weight was found to be better than that of lithium ion battery. The applications which require high-power capability rather than high-energy density, such as the sub-battery in electronic devices and motor drive assistance in electric vehicles, would be appropriate for Organic Radical batteries in the future.

  • High Power Organic Radical Battery for Emergency Power Source
    2006
    Co-Authors: Masaharu Satoh, Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro
    Abstract:

    Organic Radical battery (ORB) has been attracted much interest as a new class of rechargeable battery with excellent high-rate charging-discharging properties. This technology was initially reported by us in 2001[1]. To date, we have succeeded in synthesizing a durable polyRadical of 2,2,6,6 tetramethylpiperidine-4-yl-oxy methacrylate (PTMA) derivatives. Here we describe the preparation and properties of a high power ORB cells and their application to an emergency power source for IT equipments.

  • A New Architecture of Thin Film Battery with Organic Radical Plastic Cathode
    2006
    Co-Authors: Kentaro Nakahara, Jiro Iriyama, Shigeyuki Iwasa, Masahiro Suguro, Masaharu Satoh
    Abstract:

    Organic Radical polymers are a new type of cathode active materials for rechargeable lithium batteries. To date, a number of stable Radical polymers, such as poly (2,2,6,6-tetramethylpiperidine-4-yl-1-oxy methacrylate) (PTMA) and poly (N-tert-butylnitroxy3,5-phenylene), have been reported as plastic polymer compounds that could be used as a cathode active material in lithium batteries. Of these, PTMA has been intensively investigated as a material that combines high stability and high capacity.

Wataru Fujita - One of the best experts on this subject based on the ideXlab platform.

  • Ferromagnetic ordering in the Organic Radical cation salt BBDTA·Au(CN)2 at 8.2 K
    Dalton transactions (Cambridge England : 2003), 2015
    Co-Authors: Wataru Fujita
    Abstract:

    An Organic Radical cation salt, BBDTA·Au(CN)2, with a slipped π-stacking columnar structure and intercolumnar short contacts, shows ferromagnetic ordering at 8.2 K, the highest reported temperature among the BBDTA+ cation salts.

  • photoinduced phase transition in an Organic Radical crystal with room temperature optical and magnetic bistability
    Physical Review Letters, 2003
    Co-Authors: Hiroyuki Matsuzaki, Wataru Fujita, Kunio Awaga, Hiroshi Okamoto
    Abstract:

    A phase control by photoirradiation is successfully achieved in a spin-Peierls system of the Organic Radical crystal, 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA), which exhibits optical and magnetic bistability around room temperature with a large hysteresis loop. A nanosecond laser pulse is found to induce a transition from a diamagnetic low-temperature phase to a paramagnetic high-temperature phase both inside (296 K) and outside (11 K) the hysteresis loop. Comparison of the excitation energy dependence between transition efficiency and photoconductivity suggests that the photoinduced transition is driven by suppression of the spin-Peierls instability by the accumulation of photocarriers.

  • Intercalation of stable Organic Radicals into layered copper hydroxides
    Synthetic Metals, 2001
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    Abstract We report the intercalation of a stable Organic Radical, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidine-1-oxyl anion (PROXYL − ) into the layered copper hydroxides, Cu 2 (OH) 3 (CH 3 CO 2 )·H 2 O, by means of the anion exchange. The powder X-ray diffractions reveal the anion exchange, showing an increase in the interlayer distance. However, the elemental analyses indicate that the obtained material is Cu 2 (OH) 3.5 (PROXYL) 0.5 ·H 2 O. The temperature dependence of the magnetic susceptibilities for the intercalation compound indicates a dominant antiferromagnetic interaction in contrast to the intralayer ferromagnetic interaction in the parent compound. The EPR spectra of the intercalation compound consist of the absorption of the Organic Radical, whose temperature-variable follows the Curie law. The observed antiferromagnetic properties can be ascribed to a transition in the magnetic properties of the [Cu 2 (OH) 3 ] + layer from ferromagnetic to antiferromagnetic upon intercalation.

  • Paramagnetic-diamagnetic phase transitions in Organic Radical crystals
    Synthetic Metals, 2001
    Co-Authors: Wataru Fujita, Kunio Awaga
    Abstract:

    A large first-order magnetic phase transition in an Organic Radical, 1,3,5-trithia-2,4,6-triazapentalenyl is described, that occurs with a wide thermal hysteresis loop over the temperature range from 230 to 305 K. The high-temperature phase is paramagnetic, while the low-temperature phase is diamagnetic. The results reported here on room-temperature magnetic molecular bistability may have applications in thermal sensors, switching units and information storage media, based on Organic Radical crystals.

  • room temperature magnetic bistability in Organic Radical crystals
    Science, 1999
    Co-Authors: Wataru Fujita, And Kunio Awaga
    Abstract:

    A large first-order magnetic phase transition in an Organic Radical, 1,3,5-trithia-2,4,6-triazapentalenyl, is described. The transition occurs with a wide thermal hysteresis loop over the temperature range 230 to 305 kelvin. The high-temperature phase is paramagnetic, and its structure consists of a uniform one-dimensional stacking of the Radical. The low-temperature phase is diamagnetic because of strong dimerization along the stacking direction. The results may have applications in thermal sensors, switching units, and information storage media based on Organic Radical crystals.