PEO-based polymer electrolytes

Armand, and W. S. Howells, Solid State Ionics, 147, 225 (2002). Coherent Neutron Scattering from PEO and a PEO-Based Polymer Electrolyte. 

Figure 6.42 Temperature dependence of conductivity for various PEO-based polymer electrolytes containing divalent cations. Reprinted, by permission, from L. V. Interrante, L. A. Casper, and A. B. Ellis, eds.. Materials Chemistry, p. 110. Copyright 1995 by the American Chemical Society.

Ramesh,S.,Ramesh,K.,Arof,A.K. [2013).Fumedsilica-dopedpoly(vinyl chloride]-poly(ethylene oxide) [PVC/PEO)-based polymer electrolyte for lithium ion battery IntJ. Electrochem. Set, 8[6), 8348-8355. 

Another approach extensively apphed in recerrt years to improve the ion conductivity ((, lithiirm ion transference number (C), mechanical properties, and the electrode-electrolyte interfacial stability of a polymer electrolyte is the addition of inorganic or ceramic fillers into the polymer-salt complexes (Capiglia et al., 1999 Kim et al., 2003 Chen-Yang et al., 2008 Croce et al., 2001 Rahman et al., 2009 Shen et al., 2009 Zhang et al., 2011 Munichandratah et al., 1995 Wiec-zorek, 1992). Micro and nano-sized inorganic filler such as silicone oxide (SiO ), alumina (AI2O3), ceria (CeO ), and so on are incorporated into PEO-salt complex in an effort to improve the mechanical, thermal stabihty, and ion conductivity of PEO-based polymer electrolytes. The effect of nano-fillers on the thermal properties of the PEO-based polymer complex varies with the type of nano-particles as well as the polymer-salt complex host matrix. 

TABLE 1 Different parameters (r, AH Xc) obtained from DSC studies for PEO-based polymer electrolytes and CPE... 

Figure 7.5 Conductivity Arrhenius plots of ceramic-free and composite PEO-based, polymer electrolytes, w/o = weight percentage.

G. B. Appetecchi, F. Alessandrini, R. G. Duan, A. Arzu, J. Power Sources 2001, 101, 42-46. Electrochemical testing of industrially produced PEO-based polymer electrolytes. 

S. SyUa, J.-Y. Sanchez, M. Armand, Electrochim. Acta 1992,37,1699-1701. Electrochemictil study of linear and crossUnked PEO-based polymer electrolytes. 

R. Tao, T. Fujrnamr, J. Power Sources 2005,146, 407-411. Application of mixed-salts composed of lithium borate and lithium aluminate in PEO-based polymer electrolytes. 

When Armand [16, 17] presented the results of his original studies on PEO-based polymer electrolytes, he was influenced by knowledge of the conduction processes in conventional, crystalline electrolytes and therefore envisaged transport within the ionically conducting polymer as taking place in the crystalline regions. This seemed implausible to polymer chemists and Berthier [19] was soon able to show by solid state NMR studies that ionic transport in fact occurred within the amorphous regions. 

The compact interlacing of crystalline and amorphous regions within typical PEO-based polymer electrolytes could well account for the characteristic impedance plots obtained for these materials [20]. Such plots are characterized (Figure 1.4) by depressed semi-circles and tilted spikes, indicative of constant phase element (CPE) behaviour. A CPE can be thought of as a leaky capacitor such as could be formed by a thin imperfect dielectric (the crystalline lamella) separating the amorphous, inter-lamellar conducting regions. 

One of the important ways of overcoming the disadvantage of inadequate room temperature conductivity in PEO-based polymer electrolytes that will be discussed later is the incorporation of plasticizers. It is common to refer to polymers as plastic materials but many types of polymer including some... 

Figure 8.13 illustrates the response of this EW in terms of cyclic voltammetry. In the cathodic cycle the window is transparent (combination of WO3 in the pristine state and of fully lithiated LiyNi03) and in the anodic cycle the window becomes reflective (dark blue, lithiated LixW03). However, as in the previously discussed case of ECDs, the temperature-dependent conductivity of the electrolyte is of crucial importance for this EW, whose response becomes manifest only above 60°C, namely at temperatures higher than the crystalline to amorphous transition point. In fact, at this temperature the solid-state EW operates with a good transmittance variation (i.e. from 20% to 55%) and with an excellent cyclability (Figure 8.14). However, the response time is slow, thus confirming that more versatile windows require the relacement of PEO-based polymer electrolytes with electrically improved materials having fast ion transport at ambient and subambient temperatures [40].

Saboungi ML et al (2002) Coherent neutron scattering from PEG and a PEO-based polymer electrolyte. Solid State Ionics 147 225... 

Pawlowska A, Zukowska G, Kalita M, Solgala A, Patzuchowski P, Siekierski M (2007) The effect of receptor-polymer matrix cranpatibility on properties of PEO-based polymer electrolytes containing a supiamolecular additive. Part 1. Studies on phenomenon of compatibility. J Power Sources 173(2) 755-764... 

Shin J-H, Henderson WA, Passerini S (2005) PEO-based polymer electrolytes with ionic liquids and their use in lithium metal-polymer electrolyte batteries. J Electrochem Soc 152(5) A978-A983. doi 10.1149/l.1890701... 

X. Qian, N. Gu, Z. Cheng, X. Yang, E. Wang, and S. Dong [2002] Plasticizer Effect on the Ionic Conductivity of PEO-Based Polymer Electrolyte, Materials Chemistry and Physics 74, 98-103. 

The coloration efficiency (tf) was calculated using absorbance chaises (AA) at 560 nm for BBL and at 522 mn for BBB. The tj values for BBB ECDs decreased as the BBB film thickness increased, whereas an opposite trend was observed for BBL ECDs. Therefore, the electrochemical redox reaction probably does not occur efficiently with a thick BBB film. Lifetime measurements were performed by switching potentials fi om neutral to reduced state. ECDs with PEO and PMMA-based polymer electrolytes produced lifetimes with more than 30,000 switching cycles. Despite their better conductivity, PEO-based polymer electrolyte yielded ECD with shorter lifetimes dian those wifii the PMMA-based electrolyte, since an ECD with PMMA lasted for more than 100,000 switching cycles. Passivation of V2OS, such as the formation of PEO-VaOs con und (7), may be possible during cycling and cause fiiis shorter lifetime. 

The interfacial phenomena in solid LiX/PE systems were extensively studied by Scrosati et al For the dry PEO-based polymer electrolytes it was shown that the interfacial stability can be significantly enhanced by decreasing the ceramic particle size to the scale of nanometers. The mechanism of the processes leading to improved stability is not well understood and some explanations include scavenging effects and screening of the electrode with the ceramic phase. "... 

Ibrahim, S. and Johan, M.R. (2012) Thermolysis and conductivity studies of poly(ethylene oxide) (PEO)-based polymer electrolytes doped with carbon nanotubes. Int. J. Electrochem. Sci., 7, 2596-2615. 

Derrien, G., Hassoun, J., Sacchetti, S., and Panero, S. (2009) Nanocomposite PEO-based polymer electrolyte using a highly porous, super acid zirconia filler. Solid State Ionics, 180,1267-1271. 

A gel electrolyte is a polymer gel that confines a liquid electrolyte. Gel electrolytes have better ionic conductivity than polymer electrolytes. Wang et al. have studied poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) gel electrolyte with plasticizers such as EC-DMC, and PC-EC-DEC for Li-S batteries at room temperature. The ionic conductivity is improved significantly to about 1.2 X 10 Scm, which is much higher than that of PEO-based polymer electrolyte. High discharge capacity and utilization of sulfur are obtained with PAN-S [70, 71] and C-S [46, 69] composite electrodes. However, much lower utilization of sulfur is obtained when PVDF [134] or PVDF-HFP [119] are combined with TEGDME as a plasticizer. When TEGDME combines with EC as the plasticizer for microporous PVDE-HEP gel electrolytes, a better performance is observed in Hthium-sulfur batteries [31]. 

It is clear from this work that PEO easily forms solid solutions with a variety of salts of Pb(II) and Mg(II) over a wide range of compositions. Continuing investigations have also shown that similar PEO-based polymer electrolytes can be formed with halides of Ca(II), Ba(II)), Cd(II), Ni(II), Zn(II), and other divalent cations [11]. 

CapigUa, C., MustareUi, P., Quartarone, E., Tomasi, C., Magistris, A. (1999) Effects of nanoscale Si02 on the thermal and transport properties of solvent-free, poly(ethylene oxide) (PEO)-based polymer electrolytes. Solid State Ionics, 118, 73-79. 

The transfer of Li+ ions happens mainly in the amorphous region of the PEO-based polymer electrolyte, and PEO is easily crystallized. The solubility of lithium salt in the amorphous phase is low and the number of carriers is small. Compared to liquid electrolyte at or below room temperature, its ionic conductivity is usually in the order of 10 S/cm. This limits the application of PEO-based polymer electrolytes. 

Mizumo, T, KajUiara, T, Yamada, T, Ohshita, J. 2013. Preparation and utilization of poly(methacryloylsilatrane) as a salt-dissociation enhancer in PEO-based polymer electrolytes. Polvm. Adv. Tech. 24 705-714. 

Figure 1.7 Conductivity Arrhenius plots of composite, PEO-based, polymer electrolytes. Also the plot of a ceramic-free sample is reported for comparison...

On the basis of the model described above, one would expect that the enhancement of the transport properties should depend upon the degree of acidity of the ceramic s surface states. This is indeed the case as demonstrated by the behaviour of PEO-based polymer electrolytes using ceramic fillers with a high surface acidity, e.g. the sulfate-promoted superacid zirconia, S-ZrOi. The results show that this ceramic filler considerably enhances the transport properties of the electrolyte. 

Pandey GP, Kumar Y, Hashmi SA (2011) Ionic liquid incorporated PEO based polymer electrolyte for electrical double layer capacitors a comparative study with lithium and magnesium systems. Solid State Ion 190(l) 93-98... 

FAN, L., NAN, c. and ZHAO, s., 2003. Effect of modified Si02 on the properties of PEO-based polymer electrolytes. Solid State Ionics, 164(1-2), 81-86. 

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