Rechargeable batteries with organic radical cathodes

Nakahara, K.; Iwasa, Shigeyuki; Satoh, Masaharu; Morioka, Yukiko; Iriyama, Jiro; Suguro, Masahiro; Hasegawa, Etsuo

doi:10.1016/s0009-2614(02)00705-4

Cited by 610 publications

(589 citation statements)

References 2 publications

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“…Additionally, CTF1--400--1 is the only material in this series with long range order as evi--denced by the two broad reflections in the XRD pattern, likely due to the sheet--like structure proposed by Kuhn et al 19 Increasing the ZnCl 2 equivalents 19 or increasing the preparation temperature above 400°C results in reduced local order, causing broadened signals in the FTIR spec--tra, and reduced long range order, as evidenced by the absence of reflections in the XRD patterns ( Figure 2). MAS 13 C ssNMR can give more insight into the short range order of the materials. The CTF1--400--1 spectrum ( Figure 2c) shows a sharp resonance at 170 ppm correlated to C in the triazine ring.…”

Section: Resultsmentioning

confidence: 99%

“…Characterization of the short and long range order in the CTF1 materials with (a) FTIR spectroscopy, (b) XRD, and (c) CP--MAS 13 C ssNMR. The wavenumber range in which triazine stretches are expected is highlighted by the orange box in (a) and the resonance of 13 C in the triazine ring is highlighted by the dashed line in (c). Due to the extent of carbonization of CTF1--600, a 13 C NMR spectrum was unable to be acquired.…”

Section: Resultsmentioning

confidence: 99%

“…Very stable oxygen--centered radical species such as nitroxide radicals can exhibit both n-- and p--doped states by either acting as an oxidant by accepting an electron to pair the unpaired radical or acting as a reductant by donating the unpaired electron. 13,14 Similarly, it was recently suggested that rigid networks containing triazine moieties, termed amorphous covalent triazine--based frameworks (CTF), can also exhibit bipolar states to achieve reversible Figure 1. The covalent triazine--based frameworks, or CTFs, con--tain 1,3,5--triazine moieties bridged by rigid, conjugated units such as phenylene (CTF1) and 2,2'--bipyridyl (bipy--CTF).…”

Section: Introductionmentioning

confidence: 99%

“…The spectra were rec--orded on a X--band (≈9 GHz) Bruker EMX spectrometer operating at 100 kHz field modulation, 2.0 μW (20 mW for CTF1--500) microwave power and fitted with a high sensitivity cavity. Cross polarization magic angle spinning (CP--MAS) solid--state nuclear magnetic resonance (ssNMR) spectra were recorded at ambient temperature on a BRUKER DSX500 Avance NMR spectrometer (Bruker Biospin, Germany) with an external magnetic field of 11.75 T. The operating frequencies are 500.1 MHz and 125.7 MHz for 1 H and 13 C, respectively, and the spectra were referenced relative to TMS. The samples were meas--ured with a delay time of 1 s and a pulse length of 2.5 µs.…”

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confidence: 99%

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Lithium Charge Storage Mechanisms of Cross-Linked Triazine Networks and Their Porous Carbon Derivatives

See¹,

Hug

Schwinghammer

et al. 2015

Chem. Mater.

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Redox active electrode materials derived from organic precursors are of interest for use as alternative cath--odes in Li batteries due to the potential for their sustainable production from renewable resources. Here, a series of or--ganic networks that either contain triazine units, or are derived from triazine--containing precursors are evaluated as cathodes versus Li metal anodes as possible active materials in Li batteries. The role of the molecular structure on the electrochemical performance is studied by comparing several materials prepared across a range of conditions allowing control over functionality and long range order. Well--defined structures in which the triazine unit persists in the final material exhibit very low capacities at voltages relevant for cathode materials (<10 mA.h g -1 ). Relatively high, reversible capacity (around 150 mA.h g -1 ), is in fact displayed by amorphous materials with little evidence of triazine functionality. This result directly contradicts previous suggestions that the triazine unit is responsible for charge storage in this family of materials. While the gently sloping discharge and charge profiles suggest a capacitive--type mechanism - further con--firmed by the trend of increasing capacity with increasing surface area - electron paramagnetic resonance spectroscopy studies show that the materials exhibiting higher capacities also display larger signals, potentially implicating unpaired spins in a charge storage mechanism that could involve charge transfer.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Lithium Charge Storage Mechanisms of Cross-Linked Triazine Networks and Their Porous Carbon Derivatives

See¹,

Hug

Schwinghammer

et al. 2015

Chem. Mater.

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“…3 Recently, we have explored and utilized nitroxide polymers as cathode-active, charge-storage materials for secondary Li-ion batteries. [4][5][6][7][8][9] The organic radical battery composed of a radical polymer cathode has several advantages: high charge capacity (ca. 100-140 mAh g À1 ), high-charging and discharging rate performance (30 s for complete charge), and long cycle life often exceeding 1000 cycles.…”

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confidence: 99%

Electrospinning of radical polymers: redox-active fibrous membrane formation

Suga

Hunley

Long

et al. 2011

Polym J

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Redox-active but highly durable nitroxide radicals, that is, 2,2,6,6-tetramethylpiperidinyl-4-oxy (TEMPO), enabled direct electrospinning of radical-containing polymers without additional processing aids (such as polymer blends, post-doping, or protection/deprotection) and produced redox-active fibrous membranes with high surface area. The solution rheological behavior of the TEMPO-substituted polymethacrylate was similar to the neutral conventional polymers, and electrospinning of the radical polymers yielded submicrometer-scaled fibrous membranes without any defects on the radical moiety. The obtained membrane exhibited stable redox response, leading to redox catalysts or electrode-active materials toward organic-based flexible rechargeable battery. Polymer Journal (2012) 44, 264-268; doi:10.1038/pj.2011.120; published online 7 December 2011Keywords: electrospinning; functional polymers; radical; redox INTRODUCTION Among stable organic radical molecules that possess an unpaired electron, nitroxide radicals (such as 2,2,6,6-tetramethylpiperidinyl-4-oxy (TEMPO)) have attracted much attention due to their utilization as spin-labels, spin traps, and capping agents for controlled radical polymerization. 1 Besides, based on the stable redox couple between the nitroxide radical and its oxidized form (oxoammonium cation, Scheme 1), nitroxide-functionalized polymers and organic/inorganic composites have been employed as heterogeneous redox reagents, which catalyze the oxidation of alcohols into aldehydes and ketones. 2 This metal-free oxidation process has resurfaced as a green or environmentally-compatible chemical process. 3 Recently, we have explored and utilized nitroxide polymers as cathode-active, charge-storage materials for secondary Li-ion batteries. [4][5][6][7][8][9] The organic radical battery composed of a radical polymer cathode has several advantages: high charge capacity (ca. 100-140 mAh g À1 ), high-charging and discharging rate performance (30 s for complete charge), and long cycle life often exceeding 1000 cycles. For both applications, to enhance the turnover cycles for catalysts or charge/discharge performance for electrode-active materials, construction of nitroxide supports with high surface area has an important role due to efficient mass (substrate or counter ion) transfer accompanied by the redox reaction. 10 Prompted by the design of soft portable electronic equipments, such as roll-up displays and wearable devices, the development of bendable and flexible batteries has attracted increased interest. 11 A fibrous membrane morphology improves mechanical flexibility and possesses an enhanced surface area to volume ratio.

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Curved π‐Conjugated Stable Open‐Shell Systems Possessing Three‐Dimensional Molecular/Electronic Spin Structures

Ueda

2011

Fragments of Fullerenes and Carbon Nanotubes

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Rechargeable batteries with organic radical cathodes

Cited by 610 publications

References 2 publications

Lithium Charge Storage Mechanisms of Cross-Linked Triazine Networks and Their Porous Carbon Derivatives

Lithium Charge Storage Mechanisms of Cross-Linked Triazine Networks and Their Porous Carbon Derivatives

Electrospinning of radical polymers: redox-active fibrous membrane formation

Curved π‐Conjugated Stable Open‐Shell Systems Possessing Three‐Dimensional Molecular/Electronic Spin Structures

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