What Can We Learn from Ionic Conductivity Measurements in Polymer Electrolytes? A Case Study on Poly(ethylene oxide) (PEO)–NaI and PEO–LiTFSI

Stolwijk, N. A.; Wiencierz, Manfred; Heddier, Christian; Kösters, Johannes

doi:10.1021/jp2111956

Cited by 58 publications

(70 citation statements)

References 28 publications

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“…We note that value of B determined for the lithiated and magnesiated versions of PEO− P(STFSI)(5-3.2) are similar, within 10%, and within the range typically observed for PEO-based polymer electrolytes with added salt. 27,28 The major cause of the difference in conductivity values observed for the PEO−P[(STFSI)Li] and PEO−P[(STFSI) 2 Mg] is highlighted in Figure 2b, where A from VTF analysis is plotted versus the volume fraction of ioncontaining block, ϕ PSTFSI . In the case of the lithiated polymers, A Li directly correlates with the total concentration of charge, as demonstrated by the linear fit through the origin in Figure 2b.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Relationship between Ion Dissociation, Melt Morphology, and Electrochemical Performance of Lithium and Magnesium Single-Ion Conducting Block Copolymers

et al. 2016

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Single-ion conducting block copolymers, such as poly(ethylene oxide)-b-poly[(styrene-4-sulfonyltrifluoromethylsulfonyl)imide lithium] (PEO−P[(STFSI)Li]), represent an exciting new class of materials capable of improving the performance of solid-state batteries with metal anodes. In this work, we report on the synthesis and characterization of a matched set of lithiated (PEO−P[(STFSI)Li]) and magnesiated (PEO−P[(STFSI) 2 Mg]) single-ion conducting diblock copolymers. We measure the temperature dependence of ionic conductivity, and through analysis using the Vogel−Tamman− Fulcher (VTF) relation, demonstrate that ion dissociation is significantly lower for all PEO−P[(STFSI) 2 Mg] samples when compared to their PEO−P[(STFSI)Li] counterparts. The VTF parameter characterizing the activation barrier to ion hopping was similar for both cations, but the VTF prefactor that reflects effective charge carrier concentration was higher in the lithiated samples by an order of magnitude. We study the melt morphology of the single-ion conducting block copolymers using temperature-dependent X-ray scattering and use the mean-field theory of Leibler to extract the effective Flory−Huggins interaction parameter (χ) for PEO/P[(STFSI)Li] and PEO/P[(STFSI) 2 Mg] from the X-ray scattering data. We demonstrate a linear relationship between the charge-concentration-related VTF parameter and the parameter quantifying the enthalpic contribution to χ. It is evident that ion dissociation and block copolymer thermodynamics are intimately coupled; ion dissociation in these systems suppresses microphase separation.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Relationship between Ion Dissociation, Melt Morphology, and Electrochemical Performance of Lithium and Magnesium Single-Ion Conducting Block Copolymers

et al. 2016

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“…Ions (mainly from added salt, although a certain contribution of agar cannot be discarded due to its agaropectin) are mainly transferred through H-bonds in gels. Those gels are water-rich, Changes in conductivity can also be affected to a lesser extent by segmental motion of polymer chains as Vogel-Tammann-Fulcher (VTF) model suggests [42]. VTF model describes the curvature of conductivitytemperature plot, as 70% glycerol curve suggests.…”

Section: Electrical and Electrochemical Measurements 341 Effect Ofmentioning

confidence: 99%

Design of gel electrolytes for electrochemical studies on metal surfaces with complex geometry

Monrrabal

Guzmán

Hamilton

et al. 2016

Electrochimica Acta

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“…Eqn (3) is used to describe the role of segmental dynamics, dictated by T g , on ion transport. 17 19,20 Extensive simulations work predicting salt-solvent coordination and ion transport in polymer systems has been done by Borodin and Smith. 21 Hou et al and Gouvernour et al have measured the motion of dissociated ions using electrophoretic NMR.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of ion transport in perfluoropolyether electrolytes with a lithium salt

et al. 2017

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Perfluoropolyethers (PFPEs) are polymer electrolytes with fluorinated carbon backbones that have high flash points and have been shown to exhibit moderate conductivities and high cation transference numbers when mixed with lithium salts. Ion transport in four PFPE electrolytes with different endgroups was characterized by differential scanning calorimetry (DSC), ac impedance, and pulsed-field gradient NMR (PFG-NMR) as a function of salt concentration and temperature. In spite of the chemical similarity of the electrolytes, salt diffusion coefficients measured by PFG-NMR and the glass transition temperature measured by DSC appear to be uncorrelated to ionic conductivity measured by ac impedance. We calculate a non-dimensional parameter, β, that depends on the salt diffusion coefficients and ionic conductivity. We also use the Vogel-Tammann-Fulcher relationship to fit the temperature dependence of conductivity. We present a linear relationship between the prefactor in the VTF fit and β; both parameters vary by four orders of magnitude in our experimental window. Our analysis suggests that transport in electrolytes with low dielectric constants (low β) is dictated by ion hopping between clusters.

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What Can We Learn from Ionic Conductivity Measurements in Polymer Electrolytes? A Case Study on Poly(ethylene oxide) (PEO)–NaI and PEO–LiTFSI

Cited by 58 publications

References 28 publications

Relationship between Ion Dissociation, Melt Morphology, and Electrochemical Performance of Lithium and Magnesium Single-Ion Conducting Block Copolymers

Relationship between Ion Dissociation, Melt Morphology, and Electrochemical Performance of Lithium and Magnesium Single-Ion Conducting Block Copolymers

Design of gel electrolytes for electrochemical studies on metal surfaces with complex geometry

Mechanism of ion transport in perfluoropolyether electrolytes with a lithium salt

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