Nonaqueous polymer electrolytes conductivity

In the case of ion conductive polymers, gel polymer electrolytes which consist of a polymer matrix, organic solvents and supporting electrolyte, were introduced as novel nonaqueous electrolyte systems in electrochemical applications, such as rechargeable batteries and electric double layer capacitors [3-5], Recently, considerable attention has been devoted to the application of gel poly-... 

When it comes to practical application, the actual conductance (the inverse of resistance R) instead of specific conductivity is the important variable. This is the reason why polymer electrolytes have drawn so much attention as a potential component of allmli-metal batteries aithough their specific conductivities are usually low ( 10 S cm ) compared with those at nonaqueous eiectrolytes (-10 S cm ). Calculate the conductance of 1.0 A/ LiSOjCFj in poiy(ethyiene oxide) and propylene carbonate, respectively. The former is fabricated into a fiim of 10 Tm thickness and the latter is soaked with porous separator of 1 mm thickness. (Xu)... 

Copolymers of pyrrole and 2,2 -bithiophene were prepared by electropolymerization using mixed monomer-containing nonaque-ous electrolyte solutions by Peters and van Dyke [729]. CVs of the polymer film showed three oxidation peaks. Two could be matched with the corresponding oxidation peaks of the homopolymers the third (in between) may be caused by a random copolymer. Based on supporting evidence obtained from in situ UV-vis spectra, three distinct redox couples could be identified. Two were assigned to short blocks of PPy and poly(2,2 -bithiophene) the third was assigned to the mentioned copol3mer. Electric conductivity was lower like for pure PPy. 

Among lyogels that contain nonaqueous solvent, elastic gels are especially noteworthy for battery applications. An elastic gel made of a polymer electrolyte can be prepared by applying heat or light onto the mixture of three components, namely, a network polymer from a polymer, a crosslinkable oligometer or a monomer, and electrolyte salt and solvent. It can exhibit the ionic conductivity comparable to solutions. The... 

As discussed previously in the section on primary batteries, an acrylate is often used as a crosslinkable monomer to form a polymer matrix for a nonaqueous electrolyte. The salt-in-polymer type polymer electrolyte made by dissolving trifluoroethylene glycol methacrylate into methoxy poly(ethylene glycol methacrylate) forms a comb-like network structure at the covalently bonded portion. The ethylene oxide chain consists of 22 monomer units, and the ionic conductivity at room temperature is reported to be 10 S/cm. If sodium thiocyanate is used [30] instead of lithium trifluoromethane sulfonate, the ionic conductivity reduced to 10 S/cm. However, by adding 50 wt% of PC as a plasticizer, the ionic conductivity reaches 10 " S/cm. 

Several ofher cross-linking methods can be applied. For example, acrylonitrile, methyl methacrylate (MMA), and its EO derivatives can be copolymerized and then cross-linked with diisocyanate. A thin gel membrane can be prepared by soaking a polyolefin nonwoven fabric in a solution of reactant(s), which is fhen cross-linked by means of ultraviolet radiation. The thickness of fhis fhin gel membrane is 50-100 pm, and the ionic conductivity is 2-4 X 10 3 S/cm. Compared to the gel polymer electrolyte made from dry PAN, fhis process is much simpler, and the energy consumption is 10% lower. However, there are also disadvantages. For example, imreacted monomer and residual catalyst are difficult to remove from the gel polymer electrolyte, leading to reduced ionic conductivity and stability of the polymer. To overcome these disadvantages, the acrylonitrile monomer is first polymerized in nonaqueous electrolyte, and then the unreacted monomer is removed by vacuum. Finally, a multifunctional monomer is added, and the battery is filled with the mixed solution. It is solidified by heating to get the gel polymer electrolyte. 

For this reason, other types of electrolytes are used in addition to aqueous solutions (i.e., nonaqueous solutions of salts (Section 8.1), salt melts (Section 8.2), and a variety of solid electrolytes (Section 8.3). More recently, a new type of solid electrolyte is being employed more often (i.e., water-impregnated ionically conducting polymer films more about them in Chapter 26). 

This book focuses on three types of nonaqueous systems—liquid electrolyte solutions, ionically conducting polymers, and molten salts—with emphasis on the more commonly used liquid systems. It provides a review of a variety... 

Other nonaqueous systems, which were mentioned in the first chapter, such as ionically conducting polymers, molten salts and solid electrolytes, have uses that are more specific. Hence, experimental aspects that are related to polymer based systems and molten salts are mentioned in the chapters that deal with them. 

In a recent patent application, Angell et al. described a series of alkylammonimn PILs, which are potentially useful as nonaqueous electrolytes in high-temperature polymer membrane fuel cells. The PILs investigated were stable to temperatures between 200 and 250 C, had conductivities comparable to aqueous solutions, and could be enhanced through the addition of a base with a pA a value intermediate between that of the acid and the base. ... 

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