Solid Polymer Electrolyte electrochemical properties

In addition to the modified electrodes described in the previous sections, which usually involve a conductive substrate and a single film of modifying material, more complicated structures have been described. Typical examples (Figure 14.2.4) include multiple films of different polymers (e.g., bilayer structures), metal films formed on the polymer layer (sandwich structures), multiple conductive substrates under the polymer film (electrode arrays), intermixed films of ionic and electronic conductor (biconductive layers), and polymer layers with porous metal or minigrid supports (solid polymer electrolyte or ion-gate structures) (6,7). These often show different electrochemical properties than the simpler modified electrodes and may be useful in applications such as switches, amplifiers, and sensors. 

T. Sakai, H. Takenaka, N. Wakabayashi, Y. Kawami, E. Torikai, Gas permeation properties of solid polymer electrolyte (SPE) membranes. Journal of the Electrochemical Society 1985, 132, 1328-1332. 

Wetjen M, Kim GT, Joost M, Winter M, Passerini S. Temperature dependence of electrochemical properties of cross-linked poly (ethylene oxide)/lithium bis(trifluoromethane-sulfonyl)imide/n-butyl-n-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide solid polymer electrolytes for lithium batteries. Electro-chimica Acta 2013 87 779-87. 

In Chapter 10, the authors will demonstrate the preparation techniques for ASPEM and the characterization results. The relationship between structure and properties will be discussed and compared. The double-layer carbon air cathodes were also prepared for solid-state alkaline metal fuel cell fabrication. The alkaline solid state electrochemical systems, sueh as Ni-MH, Zn-air fuel cells, Al-air fuel cells, Zn-Mn02 and Al-Mn02 cells, were assembled with anodes, cathodes and alkaline solid polymer electrolyte membranes. The electrochemical cells showed excellent cell power density and high electrode utilization. Therefore, these PVA-based solid polymer electrolyte membranes have great advantages in the applications for all-solid-state alkaline fuel cells. Some other potential applieations include small electrochemical devices, sueh as supercapacitors and 3C electronic products. 

Momma, T., Kakuda, S., Yarimizu, H., and Osaka, T., Electrochemical redox properties of polypyrrole/Nafion composite film in a solid polymer electrolyte battery, J. Electrochem. Soc., 142, 1766-1769 (1995). 

Vassal N, Salmon E, Fauvarque JF (2000) Electrochemical properties of an alkaline solid polymer electrolyte based on P(ECH-co-EO). Electrochim Acta 45 1527... 

Ma Y, Doyle M, Fuller TF, Doeff MM, de Jonghe LC, Newman J (1995) The measurement of a complete set of transport properties fw a csolid polymer electrolyte solution. J Electrochem Soc 142 1859-1868... 

Solid polymer electrolytes made of polyethylene oxide (PEO) and polypropylene oxide (PPO) are considered because of their strong thermal conduction and electrochemical properties over a wide operating temperature range [114,115]. However, the low room temperature ionic conductivities exhibited by PEO and PPO solid state polymer electrolytes prevents successful application in ESs. When PEO was incorporated into a gel electrolyte to boost conductivity, the result indicated that PEO and PPO are actually found inferior compared to PVA and PVdF for gel electrolytes because the oxygen atoms in the polymer backbone limit ion mobility [115]. 

A limiting factor in PEMFCs is the membrane that serves as a structural framework to support the electrodes and transport protons from the anode to the cathode. The limitations to large-scale commercial use include poor ionic conductivities at low humidities and/or elevated temperatures, a susceptibility to chemical degradation at elevated temperatures and finally, membrane cost. These factors can adversely affect fuel cell performance and tend to limit the conditions under which a fuel cell may be operated. For example, the conductivity of Nafion reaches up to 1(T S cm in its fully hydrated state but dramatically decreases with temperature above the boiling temperature of water because of the loss of absorbed water in the membranes. Consequently, the developments of new solid polymer electrolytes, which are cheap materials and possess sufficient electrochemical properties, have become one of the most important areas for research in PEMFC. 

Irradiated PVDF and poly(VDF-co-TrFE) copolymer possess ferroelectric properties that allow the use of such fluorinated polymer in the domain of captors, sensors, and detectors [47,194]. Another interesting property of crosslinked poly(VDF-co-HFP) copolymer is their insolubihty in organic solvent [195]. Cured fluorinated polymers can be processed as membranes for many electrochemical applications such as fuel cell and batteries [196]. For example, a poly(VDF-co-HFP) copolymer has been crossUnked with various systems such as polyols [197], by irradiation with electron beam or y-rays [197] or with aliphatic amines [198] in order to elaborate a solid polymer electrolyte for non aqueous lithium battery [197,198]. This electrolyte is particularly interesting for its ionic conductivity, its adhesion with an electro-conductive substrate and also remarkably enhanced heat resistance. 

A solid polymer electrolyte that meets all the practical requirements has not yet been found, and the development of new polymer electrolyte systems is still needed. By rationally designing new polymers, the electrochemical and mechanical properties of the polymer electrolytes are expected to improve. For example, the polymer shown in Figure 10.38 has a coil structure and has an ionic conductivity of 4.24 x 10 S/cm at 30°C. Further improvement of the ionic conductivity can be expected after further modification such as finding a good salt-dissociation enhancer like methacryloylsilatrane, which enhances the ionic conductivity to 3.1 x 10" S/cm at 80°C [25]. 

One solution might be to incorporate nanoparticles that would improve electrochemical stabihty and mechanical properties without decreasing ionic conductivity. The most conamon polymers used as the polymer matrix in gel polymer electrolytes are poly(vinylidene fluoride), PVDF, and poly-methymethacrylate, PMMA.The nanoparticles used in gel polymer electrolytes are the same as those used in solid polymer electrolytes, i.e. organic ciayi26.iz7.i28 and metal oxide fillers. ... 

These examples and the general subjects mentioned above illustrate that ion conduction and the electrochemical properties of solids are particularly relevant in solid state ionics. Hence, the scope of this area considerably overlaps with the field of solid state electrochemistry, and the themes treated, for example, in textbooks on solid state electrochemistry [27-31] and books or journals on solid state ionics [1, 32] are very similar indeed. Regrettably, for many years solid state electrochemistry/solid state ionics on the one hand, and liquid electrochemistry on the other, developed separately. Although developments in the area of polymer electrolytes or the use of experimental techniques such as impedance spectroscopy have provided links between the two fields, researchers in both solid and liquid electrochemistry are frequently not acquainted with the research activities of the sister discipline. Similarities and differences between (inorganic) solid state electrochemistry and liquid electrochemistry are therefore emphasized in this review. In Sec. 2, for example, several aspects (non-stoichiometry, mixed ionic and electronic conduction, internal interfaces) are discussed that lead to an extraordinary complexity of electrolytes in solid state electrochemistry. 

Ketabi, S., and K. Lian. 2013. Effect of Si02 on conductivity and structural properties of PEO-EMIHSO4 polymer electrolyte and enabled solid electrochemical capacitors. Electro chimica Acta 103 174-178. 

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