A dielectric relaxation study of nanocomposite polymer electrolytes

Money, Benson K.; Hariharan, K.; Swenson, Jan

doi:10.1016/j.ssi.2012.04.025

Cited by 33 publications

(44 citation statements)

References 30 publications

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“…These relaxations are commonly observed in typical amorphous materials . Compared with the typical polyether PEO, the intensity of α relaxation in PEC is smaller, because local rotational motion scarcely occurs in PEC, which has a rigid carbonate structure in each repeating unit of the main chain. As the salt concentration increases the intensity of α relaxation in Figure a increases, and the peak of α relaxation in Figure b is clearly shifted to lower frequencies, whereas the β relaxation does not change.…”

Section: Resultsmentioning

confidence: 98%

Dielectric Relaxation Behavior of a Poly(ethylene carbonate)‐Lithium Bis‐(trifluoromethanesulfonyl) Imide Electrolyte

Motomatsu

Kodama

Furukawa

et al. 2015

Macro Chemistry & Physics

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A new class of polymer electrolytes, consisting of poly(ethylene carbonate) (PEC) and metal salts, is expected to find application in all‐solid‐state batteries because of its excellent performance as an electrolyte. To study the ion‐conductive mechanism in PEC‐based electrolytes, broadband dielectric spectroscopy is used to analyze the correlation between dielectric relaxation and ionic conduction in PEC‐lithium bis‐(trifluoromethanesulfonyl) imide electrolytes over a broad range of salt concentration (0–150 mol%) at 40 °C. The PEC system has two relaxation modes, α and β, associated respectively with the segmental motion and the local motion of PEC chains. The conductivity increases exponentially with increasing salt concentration, while the α relaxation frequency (fα) decreases with increasing strength (Δεα) at low salt concentrations, whereas in contrast fα increases with Δεα being saturated at high salt concentrations above 10 mol%. It is believed that the mobility of PEC segment at high concentration is enhanced by two factors. The first is that intermolecular interactions decrease, given the existence of many ion pairs and aggregated ions around saturated PEC domains where the dissociated ions are highly concentrated. The second is that intramolecular interactions between CO and CH2 are lowered by the ion–dipole interaction.

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Section: Resultsmentioning

confidence: 98%

Dielectric Relaxation Behavior of a Poly(ethylene carbonate)‐Lithium Bis‐(trifluoromethanesulfonyl) Imide Electrolyte

Motomatsu

Kodama

Furukawa

et al. 2015

Macro Chemistry & Physics

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“…Increase of ionic conductivity following the addition of ferroelectric BaTiO 3 to different polymer matrices is ascribed to the high polarity of the filler. Money et al 63 showed that the ionic conductivity of the LiClO 4 :P(EO) 4 polymer electrolyte containing 4wt% δ-Al 2 O 3 is coupled to the structural (α) relaxation time. The strength of the β-relaxation of polymer chains increases in the presence of salt and filler particles, while the γ-relaxation remains unaffected.…”

Section: Amorphous Polymer Electrolytesmentioning

confidence: 99%

Review—On Order and Disorder in Polymer Electrolytes

Golodnitsky

Strauss

Greenbaum

2015

J. Electrochem. Soc.

204

135

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This contribution presents an overview of more than three-decades-long studies of the structure and mechanism of ion conduction in polyethylene-oxide-based solid polymer electrolytes. Conductivity in polymer electrolytes has long been viewed as confined to the amorphous phase above the glass-transition temperature (Tg). Above Tg, polymer chain motion creates a dynamic, disordered environment that was thought to play a critical role in facilitating ion transport. Difficulty of finding the amorphous polymer with sufficient ionic conductivity has raised the fundamental question of whether polymer electrolytes are intrinsically inferior to other electrolytes in terms of their charge-transport capability. Recently, enhanced ionic conductivity has been detected in ordered (longitudinally stretched and cast under gradient magnetic field) polymer electrolytes, in crystalline ion-polyether 1:6 complexes and polymer-in-salt electrolytes. These results have opened a new trend in the search for ion transport in solid polymer electrolytes. The very latest publications present new hybrid-and block-co-polymers, a new class of functional materials (polymerized ionic liquids), and new promising approaches aimed at the development of polymer-based superionic conductors with rigid nanochannel architectures that enable rapid ion transport decoupled from segmental relaxation. Solid Polymer Electrolytes-Structure and Mechanism of Ion TransportMuch research deals with high-ionic-conductive polymer electrolytes because of their current and potential applications as electrochromic and temperature-sensitive printed electronics devices, biomedical sensors, supercapacitors, solar cells and batteries. Polymer electrolytes offer pronounced advantages over conventional liquid electrolytes. These include: a versatile shape, mechanical strength and stable contact between the electrode and electrolyte interfaces. In addition, solid electrolytes are safer than liquid electrolytes as they do not have a leakage problem and because of their nontoxic, low-vaporpressure, and non-flammable properties. [1][2][3][4][5][6][7] Ion-polyether complexes (or polymer electrolytes) were first discovered by Fenton, Parker and Wright in 1973. 8 Since then, such complexes have been prepared with many different monatomic ions and indeed many different polymeric ligands. Armand in 1979 recognized that Li + -polyether complexes could be used as solid electrolytes in electrochemical devices. 9The classic polymer electrolyte comprises organic macromolecules (usually polyether polymer) that are complexed with inorganic salts. The polymer matrix must contain a Lewis base (e.g. ethylene-oxide unit, -OCH 2 CH 2 -) to solvate the lithium salt. The salt-solvent mixing entropy consists mainly of two components: translational and configurational. Contrary to the case of water, the mixing entropy for the formation of polymer electrolytes is small or even positive. The incorporation of salts into the polymer inevitably reduces the freedom of polymer-chain motion, thus causing ...

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“…Polyethylene oxide is a nontoxic semiconducting polymer of complex molecular structure {H − [O − CH 2 − CH 2 ] n − OH} with molecular weight M w =18.02 + 44.05 n >10 5 g/mol, where n is the number of repeated molecular chain‐like units of identical monomers. The pure PEO has melting point T m <72 ° C (345 K), crystallization temperature T c ≲60 ° C (333 K), and low glass transition temperature T g (≳ − 58 ° C ≅ 215 K), depending on its molecular weight, and possesses strong solvating ability for many metal ions, including Li . Besides its ability to dissolve inorganic lithium‐ion salts, PEO polymer is highly soluble in water and organic solvents (ethanol, methanol, and toluene), so it can be fabricated in the form of solid films by various solvent‐evaporation coating methods .…”

Section: Introductionmentioning

confidence: 99%

“…Not only the amorphous‐phase and crystalline‐phase regions in semicrystalline polymers, as PEO polymer, hinder their ionic conductivity and suppress dielectric relaxations but also interfacial barriers between amorphous and crystalline regions may alter their structural, conduction, and dynamical properties. Thus, it is essential to minimize crystallinity in PEO polymer and reduce amorphous‐crystalline interfacial barriers, besides simultaneously enhancing ionic conduction and dielectric relaxation in PEO films and PEO‐based electrolytes, a challenging task attempted by many researchers by using diverse routes …”

Section: Introductionmentioning

confidence: 99%

Identification of relaxation processes in pure polyethylene oxide (PEO) films by the dielectric permittivity and electric modulus formalisms

Telfah

Jafar

Jum’h

et al. 2018

Polymers for Advanced Techs

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The ac‐impedance of bulk‐like films of pure polyethylene oxide (PEO) polymer was measured as a function of frequency f in the range 0.1 to 107 Hz at various constant temperatures T (155 − 330 K). The as‐measured data were analyzed by electric permittivity and modulus formalisms to unveil which dielectric and conductive relaxation processes were responsible for their relaxation behavior below/above glass transition temperature Tg of pure PEO polymer. At T > Tg, none of the α‐, β‐, or γ‐relaxations could be inferred for studied pure PEO films from frequency variation of measured imaginary part ε′′(f, T) of complex dielectric permittivity trueε~(),fT, as low‐frequency losses masked real dielectric contribution to the measured ε′′(f, T) at low frequencies and high temperatures. However, at T < Tg, a broad, relaxation process has been observed in the high‐frequency part of their isothermal ε′′(f, T) − f spectra, which can be related to the β‐ or γ‐dielectric relaxation process. Nonlinear regressions of the measured ε′′(f, T) − f data for T < Tg yielded moral fits to a simple addition of a Havriliak‐Negami function, and a Bergman‐loss Kohlrausch‐Williams‐Watts‐type function, with the relaxation time τmax(T) obtained from Havriliak‐Negami‐fitting parameters, was found to follow a thermally activated Arrhenius‐like relaxation behavior. Conversely, representation of the imaginary part M′′(f, T > Tg) − f spectra of complex electric modulus trueM~()f=1/trueε~()f was found to depict 2 overlapped relaxation processes, which were detached well by a nonlinear regression of a simple superposition of 2 different M′′(f) expressions having the form of the universal Bergman loss function, where it was found that the relaxation time is also thermally activated.

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A dielectric relaxation study of nanocomposite polymer electrolytes

Cited by 33 publications

References 30 publications

Dielectric Relaxation Behavior of a Poly(ethylene carbonate)‐Lithium Bis‐(trifluoromethanesulfonyl) Imide Electrolyte

Dielectric Relaxation Behavior of a Poly(ethylene carbonate)‐Lithium Bis‐(trifluoromethanesulfonyl) Imide Electrolyte

Review—On Order and Disorder in Polymer Electrolytes

Identification of relaxation processes in pure polyethylene oxide (PEO) films by the dielectric permittivity and electric modulus formalisms

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