Poly : solid electrolyte

Equation (40) relates the lifetime of potential-dependent PMC transients to stationary PMC signals and thus interfacial rate constants [compare (18)]. In order to verify such a correlation and see whether the interfacial recombination rates can be controlled in the accumulation region via the applied electrode potentials, experiments with silicon/polymer junctions were performed.38 The selected polymer, poly(epichlorhydrine-co-ethylenoxide-co-allyl-glycylether, or technically (Hydrine-T), to which lithium perchlorate or potassium iodide were added as salt, should not chemically interact with silicon, but can provide a solid electrolyte contact able to polarize the silicon/electrode interface. 

Polymer electrolytes (e.g., poly (ethylene oxide), poly(propylene oxide)) have attracted considerable attention for batteries in recent years. These polymers form complexes with a variety of alkali metal salts to produce ionic conductors that serve as solid electrolytes. Their use in batteries is still limited due to poor electrode/electrolyte interface and poor room temperature ionic conductivity. Because of the rigid structure, they can also serve as the separator. Polymer electrolytes are discussed briefly in section 6.2. 

The PEO salt complexes are generally prepared by direct interaction in solution for soluble systems or by immersion method, soaking the network cross-linked PEO in the appropriate salt solution [52-57]. Besides PEO, poly(propylene)oxide, poly(ethylene)suceinate, poly(epichlorohydrin), and polyethylene imine) have also been explored as base polymers for solid electrolytes [58]. Polyethylene imine) (PEI) is prepared by the ring-opening polymerization of 2-methyloxazoline. Solid solutions of PEI and Nal are obtained by dissolving both in acetonitrile (80 °C) followed by cooling to room temperature and solvent evaporation in vacuo. Polyethyleneimine-NaCF3S03 complexes have also been explored [59],... 

Polyethylene oxide) associates in solution with certain electrolytes (48—52). For example, high molecular weight species of poly(ethylene oxide) readily dissolve in methanol that contains 0.5 wt % KI, although the resin does not remain in methanol solution at room temperature. This salting-in effect has been attributed to ion binding, which prevents coagulation in the nonsolvent. Complexes with electrolytes, in particular lithium salts, have received widespread attention on account of the potential for using these materials in a polymeric battery. The performance of solid electrolytes based on poly(ethylene oxide) in terms of ion transport and conductivity has been discussed (53—58). The use of complexes of poly(ethylene oxide) in analytical chemistry has also been reviewed (59). 

Schubert98 proposed the potential use of several ruthenium containing polymers in photovoltaic devices. A ruthenium containing poly(ethylene glycol) derivative 34 was synthesized by the functionalization of 4-(3-aminopropyl)-4-methyl-2,2-bipyridine with polyethylene glycol) (M =2800, PDI=1.05), which was activated with /V,/V-carbonyldiimidazole (Scheme 19)." Applications in solid electrolytes for DSSC was proposed. Polyester 35 was incorporated with... 

Armand M, Chabagno JM, Duclot M. Poly-ethers as solid electrolytes. In Vashishita P, Mundy JN, Shenoy GK, editors. Fast ion transport in solids. Amsterdam North-Holland Publishing 1979. 

Exposure of the n-type films to either liquid (styrene, methyl methacrylate) or gaseous (ethylene oxide, isoprene) monomers resulted in polymerization. Much of our initial work has focused on grafting of poly(ethylene oxide) (PEO) to (CH)X in an effort to render the (CH)X surface more hydrophilic and to provide covalent attachment of a material capable of functioning as a solid electrolyte (12). Films of n-type (CH)X were exposed to dry (CaH2-treated), gaseous ethylene oxide in the range 55-75°C with initial pressures being ca. 500 torr. Reaction times were typically 5 hours. The films were washed with dry, 02-free methylene chloride to remove non-covalently bound PEO and then with deaerated H2O to protonate oxyanions and remove the NaOH byproduct. The presence of bound PEO after extraction was confirmed by IR spectroscopy. 

A second class of important electrolytes for rechaigeable lithium batteries are solid electrolytes. Of particular importance is the class known as solid polymer electrolytes (SPEs). SPEs are polymers capable of forming complexes with lithium salts to yield ionic conductivity. The best known of the SPEs are the lithium salt complexes of poly (ethylene oxide) [25322-68-3] (PEO), — (CH2CH20)k—, and poly(propylene oxide) [25322-69 4] (PPO) (11—13). Whereas a number of experimental battery systems have been constructed using PEO and PPO dectrolytes, these systems have not exhibited suitable conductivities at or near room temperature. Advances in the 1980s included a new dass of SPE based on polyphosphazene complexes suggesting that room temperature SPE batteries may be achievable (14,15). 

In 1973, Peter Wright and coworkers first reported [39-41] the ionic conductivity of poly(ethylene oxide), [CH2CH20]n, (PEO), with alkali metal salts. This was followed by the visionary suggestion of M. Armand for the use of PEO as a solid electrolyte system for the transport of ions [42-43]. Since then, the area of polymer electrolytes has attracted considerable interest. In the following account, first a discussion is presented on the general features applicable to polymer electrolytes. This is followed by an account on individual polymer electrolytes, par-... 

A variety of dimensionally stable solid electrolytes consisting of a mixture of organic plasticizers such as EC, PC etc., along with structurally stable polymers such as poly( acrylonitrile) (PAN) or poly( vinyl sulfone) (PVS), or polyvinyl pyrrolidine (PVP) or polyvinyl chloride (PVC) and several lithium salts have been tested and found to have excellent ionic conductivities at ambient temperatures [155-156]. In these gel type electrolytes the primary role of the polymers PAN, PVS, PVP or PVC is to immobilize the lithium salt solvates of the organic plasticizer liquids. However, with polymers such as PAN a coordination interaction with Li+ is also quite likely. 

The synthesis of MEEP involves the reaction of poly(dichlorophosphazene) with the sodium salt of methoxy ethoxy ethanol. The byproduct in this reaction is sodium chloride which has to be separated from the polymer completely, since even traces of the ionic impurities would lead to spurious results. However, unfortunately MEEP is also soluble in water and therefore separation from sodium chloride is rendered extremely difficult. A cumbersome and lengthy dialysis procedure is required to effect the separation and purification of the polymer. Further MEEP is also hydrophilic and residual water in the polymer is an undesirable feature for a solid electrolyte particularly when involved with alkali metal salt complexes. Additionally the dimensional stability of MEEP is poor and has been commented upon above. 

USE As intensifter in photography as brominating agent in organic Synthesis as humidity indicator as wood preservative in solid-electrolyte battery as stabilizer for acetylated poly Formaldehyde. 

Electrochromic devices using poly(3-octylthiophene) associated to vanadium oxide as cathodically colouring material and a solution of polyethylene oxide (PEO) mixed with lithium perchlorate as solid electrolyte were tested [12]. Bithiophene properties were also discussed... 

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