Self-doping inspired zwitterionic pendant design of radical polymers toward a rocking-chair-type organic cathode-active material

Chae, Il Seok; Koyano, Masafumi; Oyaizu, Kenichi; Nishide, Hiroyuki

doi:10.1039/c2ta00785a

Cited by 43 publications

(33 citation statements)

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“…The procedure for the synthesis of PTMA-co-PVS was modified here relative to previous reports [35,36]. Specifically, the sodium salt form (VS-Na) of the monomer was polymerized instead of the more acidic vinylsulfonic acid (VSA) monomer; this is because the latter of these requires a neutralization step to improve the solubility of the copolymer.…”

Section: Resultsmentioning

confidence: 99%

“…Poly(2,2,6,6-tetramethyl-4-piperidyl methacrylate)-co-poly(vinylsulfonic acid sodium salt) (PTMPM-co-PVS) was synthesized via a free radical polymerization mechanism in a manner similar to previous reports [35,36]. The following is a brief example of the polymerization process.…”

Section: Ptmpm-co-pvs Synthesismentioning

confidence: 96%

“…Here, we extend this paradigm to the realm of radical polymers through the intentional addition of ion-bearing repeat units to the macromolecular architecture of PTMA; these ion-bearing repeat units serve as intramolecular dopants in order to enhance the transport ability of the copolymers relative to pristine PTMA. Specifically, we have synthesized a series of copolymers containing both PTMA and an ionic molecular dopant, poly(vinylsulfonic acid sodium salt) (PVS), using a free radical polymerization mechanism to yield poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate)-copoly(vinylsulfonic acid sodium salt) (PTMA-co-PVS) [35,36]. After confirming the macromolecular architectures of the radical polymerbased copolymers using established spectroscopic techniques, the space charge-limited hole mobility values of the copolymers were established and found to be~10 −5 cm 2 V −1 s −1 in optimized conditions and dependent on the level of intramolecular dopants.…”

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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Effect of intrachain sulfonic acid dopants on the solid-state charge mobility of a model radical polymer

2015

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Section: Resultsmentioning

confidence: 99%

Section: Ptmpm-co-pvs Synthesismentioning

confidence: 96%

Section: Contents Lists Available At Sciencedirectmentioning

confidence: 99%

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Effect of intrachain sulfonic acid dopants on the solid-state charge mobility of a model radical polymer

2015

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“…1-5 When the redox-active sites are electrochemically reversible [6][7][8][9] and are bound to a polymer chain, an electron self-exchange reaction between the neighboring sites effects the redox mediation through the polymer layer, which requires that electroneutralization by electrolyte ions is accomplished throughout the layer to maintain the electroactivity. [10][11][12] Aliphatic, or non-conjugated polymers populated with organic robust radicals such as nitroxide, [13][14][15][16][17][18][19][20][21][22][23] nitronyl nitroxide, 24,25 spirobisnitroxide 26 and galvinoxyl 27,28 have been found to be the typical examples, and their ideal redox-mediating properties 29 are different from those of conventional redox polymers such as poly (vinylferrocene), [30][31][32][33] which has been dominated by the 'break-in effect' of the electroneutralizing ions to give rise to limited charge capacity and hysteresis during the charging/discharging process. The ideal, that is, diffusion-limited behavior by the so-called 'radical polymers' 34,35 has led to reversible and exhaustive charging with the simple redox diffusive process formulated by the finite diffusion equation 36 for the layer with a discrete thickness on a current collector, 37 and by the equation for semi-infinite diffusion 36 that applies to wholly gelated cells with the radical polymer.…”

Section: Introductionmentioning

confidence: 98%

Facile charge transport and storage by a TEMPO-populated redox mediating polymer integrated with polyaniline as electrical conducting path

Oyaizu

Tatsuhira

Nishide

2014

Polym J

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A copolymer of TEMPO-and aniline-substituted norbornene was prepared by ring-opening metathesis polymerization of the corresponding monomers. Electropolymerization of the pendant aniline groups in the copolymer gave a layer of polynorbornene populated with the redox-active TEMPO pendants, in which polyaniline chain was incorporated. Electroactivity of the TEMPO pendants throughout the layer and its excellent charging/discharging cyclability, in addition to the amorphous nature of the layer, suggested that the polyaniline chain was homogeneously dispersed in the layer and that each chain served as crosslinking moiety. The effect of the polyaniline chains was further enhanced when they were formed by in-situ electropolymerization of the aniline group in the preformed layer of the copolymer/polyaniline composite. The polyaniline chain served as a conducting path to reduce the charge-transfer resistance for redox mediation, which gave rise to an excellent rate performance for the charging/ discharging process of the layer, compared with those for the composite layers of TEMPO-substituted polymers with polyaniline and other conductive additives prepared by the conventional grinding methods.

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“…Here we discuss some options for overcoming these challenges. Nishide 15 has proposed a co-polymer with alternating monomers of ionomers and redox groups, i.e., the anion is chemically bound to the organic-radical polymer. In the neutral state, the anion is coordinated with a lithium ion.…”

Section: Designs To Overcome the Limitations Of Salt Consumptionmentioning

confidence: 99%

Design of Composite Electrodes with Anion-Absorbing Active Materials

Thomas‐Alyea

Aryanpour

2016

J. Electrochem. Soc.

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Organic radical polymers (ORP) and conjugated polymers provide exceptional rate capability as cathode materials for lithium-ion batteries, albeit low volumetric energy density. To optimize overall power and energy density, we consider a composite of ORP with oxide cathode. Upon charge (oxidation), ORP absorb anions from the electrolyte, which causes the salt content in the cell to decrease during charge. Even if the ORP is only 10 volume% of the cathode, the cell's salt content will decrease by >0.6 M in practical cell designs. Furthermore, the conductivity of typical electrolytes varies strongly with concentration. We use electrochemical modeling of a composite positive electrode containing both lithium-releasing and anion-absorbing active materials to explore the tradeoffs and design implications among salt concentration, porosity, and volume fraction of ORP. Organic-radical polymers (ORP) have demonstrated exceptionally high rate capability for lithium batteries, accepting over 80% of capacity at charge rates exceeding 1000 C.1,2 The high rate capability is achieved because the polymers form a gel with liquid electrolytes, which means they have high interfacial area with the electrolyte and polymer-phase transport lengths on the order of tens of nanometers. Diffusion therefore occurs predominantly in the liquid electrolyte, whose diffusivity is several orders of magnitude higher than the solidphase diffusivity which limits the capability of conventional oxide cathode materials.Many important applications, such as electric vehicles and portable power, highly value volumetric energy density and fast charge capability. While ORPs have been discovered with good gravimetric capacity (up to 150 mAh/g), they suffer from low density (∼1 g/cm 3 ). In contrast, oxide cathodes have high density (4.6 to 5.0 g/cm 3 ), but charging and discharging rates are limited by diffusion resistance. Therefore we consider a composite electrode comprised of ORP with an oxide cathode, e.g. LiCoO 2 (LCO). The goal of the composite is to combine the high energy density of LCO with the high rate capability of ORP to maximize the overall volumetric and gravimetric power and energy density. 4,5The reaction mechanism of a prototypical ORP, 2,2,6,6-tetramethylpiperidin-1-oxyl (PTMA), is shown in Figure 1. During charge, the nitroxide radical is oxidized and the charge is balanced by absorption of an anion, e.g. PF 6− , from the electrolyte. In contrast, traditional inorganic cathode materials release lithium cations into the electrolyte during charge. All known negative electrode materials for lithium-ion batteries absorb lithium cations during charge. If a lithium-absorbing cathode is paired with a lithium-releasing anode, then there is no net change in the salt content of the cell (although there will be gradients in salt composition as lithium ions are transported from the anode to the cathode). However, the salt content will decrease during charge of a cell with cation-absorbing negative electrode and anion-absorbing positive electrode. T...

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Self-doping inspired zwitterionic pendant design of radical polymers toward a rocking-chair-type organic cathode-active material

Cited by 43 publications

References 43 publications

Effect of intrachain sulfonic acid dopants on the solid-state charge mobility of a model radical polymer

Effect of intrachain sulfonic acid dopants on the solid-state charge mobility of a model radical polymer

Facile charge transport and storage by a TEMPO-populated redox mediating polymer integrated with polyaniline as electrical conducting path

Design of Composite Electrodes with Anion-Absorbing Active Materials

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