A General Formula for Ion Concentration-Dependent Electrical Conductivities in Polymer Electrolytes (original) (raw)
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Conductivity studies on solid polymer electrolytes
Le Journal de Physique IV, 1994
This thematic lecture addresses electrochemical conductivity techniques for the study of solid polymer electrolytes. Types of conductivity are discussed first, followed by an outline of the features, applicability, and validity of DC and AC conductivity measurements. Techniques for the identification of the individual species responsible for conduction are then briefly reviewed. Résumé Cette étude aborde des méthodes de mesure de conductivité électrique des électrolytes polymères solides. On considère d' abord la conductivité ionique et électronique, par des mesures en courant continu et en courant alternatif. La détermination des nombres de transport pour qu' on puisse avoir des informations plus complètes sur les espèces responsables de la conduction est examinée ultérieurement.
Effect of molecular weight on conductivity of polymer electrolytes
Solid State Ionics, 2011
The ionic conductivity, σ, of mixtures of poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfone) imide (LiTFSI) was measured as a function of molecular weight of the PEO chains, M, over the range 0.2-5000 kg/mol. Our data are consistent with an expression σ = σ 0 + K/M proposed by Shi and Vincent [Solid State Ionics 60 (1993)] where σ 0 and K are exponential and linear functions of inverse temperature respectively. Explicit expressions for σ 0 and K are provided.
Journal of Applied Polymer Science, 1995
Two polar polymers with different dielectric constants, poly(viny1idene fluoride) (PVDF) and poly (ethylene oxide) (PEO), were each blended with a chlorine-terminated poly(ethy1ene ether) (PEC) and one of the two salts, LiBF4 and LiCF3C02, to form PECplasticized polymer electrolytes. The room-temperature ionic conductivity of the PECplasticized polymer electrolytes reached a value as high as S/cm. The room-temperature ionic conductivity of the PVDF-based polymer electrolytes displayed a stronger dependence on the PEC content than did the PEO-based polymer electrolytes. In PVDF/PEC/LiBF4 polymer electrolytes, the dynamic ionic conductivity was less dependent on temperature and more dependent on the PEC content than it was in PEO/PEC/LiBF4 polymer electrolytes. The highly plasticized PVDF-based polymer electrolyte film with a PEC content greater than CF4 (CF4 defined as the molar ratio of the repeat units of PEC to those of PVDF equal to 4) was self-supported and nonsticky, while the corresponding PEO-based polymer electrolyte film was sticky. In these highly plasticized PVDF-based polymer electrolytes, the curves of the room-temperature ionic conductivity vs. the salt concentration were convex because the number of carrier ions and the chain rigidity both increased with increase of the salt content. The maximum ionic conductivity at 30°C was independent of the PEC content, but it depended on the anion species of the lithium salts in these highly plasticized polymer electrolytes. 0 1995 John Wiley & Sons, Inc.
Conductivity behaviour of polymer gel electrolytes: Role of polymer
Bulletin of Materials Science, 2003
Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.
Effect of Mixed Ions and Ion Irradiation on Ionic Conductivity of Solid Polymer Electrolytes
IOP Conference Series: Materials Science and Engineering, 2019
It is a well known fact that conductivity in case of solid polymer electrolytes (SPEs) is due to hopping of ions assisted by the segmental motion of polymer chains. It is observed that the ionic conductivity in SPEs increases with increase in the concentration of ions. After certain critical concentration the conductivity starts decreasing due to the formation of ion pairs. In this work, an attempt is made to identify the concentration at which ion pair formation occurs and hence improve conductivity by incorporating two different ions (salts) in the polymer matrix. SPEs with mixed conducting species PEOxLiBryNaBr with different concentration of salts have been prepared and investigated. Also an attempt is made to modify the crystalline phase of the host polymer by low energy ion beam (Oxygen ion, O+1 with energy 100 keV) irradiation. These observations place ion irradiation as an effective tool in improving ionic conductivity in SPEs. Using X-ray diffraction spectra and the tempera...
Investigation on the structure and the conductivity of plasticized polymer electrolytes
Solid State Ionics, 1992
Leiling Yang l)~7~artm ('plt ~l t'~d.t'tner Mat('rm/~. 1,¢et]mg Research l,~stilute ~!l' ('hcmtca/htdu.~try. I0(~013 B('!/in,~,,, t'.R ( 'hina Electrical properties of polymer electrolytes depend on the structure ot polym¢l matrix. It ~as reported that lranst)ortalion o1" carries in polymer electrolFles was correlated with tile segment movement oF the amorphous phase. D?namic properly of amorphous phase and the cwstallinit} of electrolyte would effecl the conducti~it~ of pol}mcr electrol}tes. The properties or" I)E() Li('F~SO~ modified with additives were investigated b~ conducti',ity measurement. I)S(' and ~tt-, "~F-NMR experiments. It was tbund [hat addilives would increase ~he conten! of amorphous phase and salt concentration m amorphous phase, and improve the dynamic property of amorphous phase. The spin-spin relaxation lime for the polymer matrix is also increased. It was indicated that the glass transition temperature of modified electrolFtcs was decreased from 21 (" Ior typical PE()-Li('F~S(), dectrolytes to about -48 C. These iml)ro~ements result in the increase of the conducf.iv il,v.
A unified model for temperature dependent electrical conduction in polymer electrolytes
2001
The observed temperature dependence of electrical conduction in polymer electrolytes is usually fitted with two separated equations: an Arrhenius equation at low temperatures and Vogel-Tamman-Fulcher (VTF) at high temperatures. We report here a derivation of a single equation to explain the variation of electrical conduction in polymer electrolytes at all temperature ranges. Our single equation is in agreement with the experimental data
A computer simulation study of ionic conductivity in polymer electrolytes
Pramana, 1998
In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are assigned to sites corresponding to the different phases. A random walk (RW) is used to calculate the conductivity through the Nernst-Einstein relation. Our walk algorithm takes into account the reorganisation of the different phases over time scales comparable to time scales for the conduction process. This is a characteristic feature of the polymer network. The qualitative nature of the variation of conductivity with salt concentration agrees with the experimental values for PEO-NH 4 I and PEO-NH 4 SCN.
In-situ study of the influence of crystallization on the ionic conductivity of polymer electrolytes
2000
Simultaneous impedance measurements and optical observations of polymer electrolytes were conducted in an automated experimental setup, combining an impedance analyser, polarizing microscope with a heating stage and a digital camera. The polymer film was placed between glasses with indium tin oxide conductive layers, forming a transparent cell mounted in a custom-designed holder, which preserved an argon atmosphere. Results of in-situ studies for various compositions of poly(ethylene oxide) (PEO) with LiN(CF 3 SO 2 ) 2 salt (LiTFSI), as well as pure PEO, are presented. In the investigated systems, crystallization had a strong impact on ionic conductivity. It was found that the initial growth of crystalline structures caused only a small fraction of the total decrease of conductivity. A large decrease in conductivity was observed during the second stage of crystallization, when no significant changes in microscope picture were observed. In pure PEO and the PEO:LiTFSI 6:1 system, a dense crystalline structure developed, resulting in a decrease in conductivity of over two orders of magnitude. In dilute PEO:LiTFSI systems, a "loose" structure was formed, with amorphous areas preserved between crystallites, and conductivity decreased by only a factor of about 6.
On the Description of Conductivity in PVA-Based Composite Polymer Electrolytes: EMT Approach
In the present work, the attempt has been made to explain the influence of filler concentration on the conductivity response of PVA-based composite polymer electrolytes following the Effective Medium Theory (EMT) approach. In the present investigation, the variation in the thickness of the highly amorphous space charge layer (responsible for enhancement in conductivity), covering the dispersed grains, has been taken into account while interpreting the conductivity data. During the estimation of the surface layer conductivity the role of glass transition temperature and degree of crystallinity were also considered. The simulated conductivity data incorporating these parameters in the EMT model show a better fit to the experimental conductivity response.