Nonaqueous polymer electrolytes

Another factor also contributed to the appearance of new concepts in electrochemistry in the second half of the twentieth century The development and broad apphca-tion of hthium batteries was a stimulus for numerous investigations of dilferent types of nonaqueous electrolytes (in particular, of sohd polymer electrolytes). These batteries also initiated investigations in the held of electrochemical intercalation processes. 

As a result, the acid strength of the proton is approximately equivalent to that of sulfuric acid in nonaqueous media. In view of the excellent miscibility of this anion with organic nonpolar materials, Armand et al. proposed using its lithium salt (later nicknamed lithium imide , or Lilm) in solid polymer electrolytes, based mainly on oligomeric or macro-molecular ethers. In no time, researchers adopted its use in liquid electrolytes as well, and initial results with the carbonaceous anode materials seemed promising. The commercialization of this new salt by 3M Corporation in the early 1990s sparked considerable hope that it might replace the poorly... 

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)... 

Further studies on ion-pair formation have to be done for a reliable understanding of ion transport in multicomponent solutions and concentration dependence of transference numbers for nonaqueous electrolyte solutions, solid polymer electrolytes, and associated gels. In transport models for lithium-ion batteries, transference numbers are often introduced as constants entailing inexact results. Although the... 

Opekar F (1989) Analytical applications of metallized membrane electrodes. Electrormrilysis 1 287-295 Opekar F, Stulik K (1999) Electrochemical sensors with solid polymer electrolytes. Aneil Chim Acta 385 151-162 Otagawa T, Zaromb S, Stetter JR (1985) Electrochemical oxidation of metheme in nonaqueous electrolytes at room temperature. J Electrochem Soc 132 2951-2957... 

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. 

One of the major problems of lithium polymer electrolyte systems is the development of high interfacial resistance at the lithium/polymer electrolyte interphase. This resistance grows with time and could be as high as 10 kO cm. This resistance layer is due to the reactions of lithium with water, other impurities, and the salt anions. Similar to nonaqueous electrolytes, the solid electrolyte interphase (SET) also exists in the lithium/polymer electrolyte systems. In this case, the solid electrolyte interface (SEI) consists of the inorganic reduction products of the polymer electrolyte and its impurities. 

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. 

Polymer electrolytes, especially those recently developed, share several properties with nonaqueous electrolytes because they are based on a salt and an ion-solvating polymer with or without additional solvent The ideal nonaqueous electrolyte for practical batteries would possess the following properties ... 

Electrolytes, whether solid or liquid, are comprised of the following components an electrolyte salt, which can furnish ions for charge transport and an electrolyte medium, such as a solvent (liquid electrolyte) or polymer or other matrix (solid electrolyte). For nonaqueous liquid electrolytes, solvents such as acetonitrile. 

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