ABSTRACT:Poly[oligo(oxyethylene) methacrylate-co-sodium methacrylate] was prepared as a polymeric solid electrolyte which enables sodium single ionic conduction. A methanol solution of the mixture of oligo(oxyethylene) methacrylate and sodium methacrylate was cast and polymerized on a TeflonŸ plate. The film obtained showed a conductivity of 4.0 x 10-7 Scm -t at 80°C. The conductivity of the films depended on the sodium methacrylate content. Temperature dependence of the conductivity was analyzed as WLF-type behaviour. The ionic conduction mechanism of this film was found to be deeply affected by the segmental motion of the matrix polymer. This was also confirmed by the Vogel-Tammann-Fulcher plot for ionic conductivity.KEY WORDS Polymeric Solid Electrolyte I Sodium Conductor I Dissociation Energy I Thin Film I WLF Behaviour I Polymeric solid electrolytes with high ionic conductivity and good processibility are in serious demand for the development of electronic devices. 1 -3 Many investigations in this field have been carried out, especially on poly( oxyethylene )-alkali metal salts systems.4-13 The authors have prepared polymeric solid electrolytes to satisfy the following requirements, 14 -18 (1) construction of flexible polymer domain in which let carrier ions exist stably, (2) decrease of the T 8 of polymer solid electrolyte in order to increase the mobility of carrier ions, and (3) inhibition of the migration of counter ions. Polymeric solid electrolytes reported previously have already satisfied requirements, (1) and (2). However, the last one (3) has not always been satisfied. A secondary solid-state battery or some application of the solid electrolytes required no anion migration because that caused a serious self discharge. A few approaches * To whom correspondence should be addressed.for the single-ionic conductor were carried out with Poly[ oligo( oxyethylene) methacrylatelithium methacrylate] system,l 8 high molecular weight PEO and polyelectrolyte blend system, 19 or low molecular weight PEO and polyelectrolyte blend system. 20 We also reported the lithium polymeric solid electrolyte with single-ionic conduction, and the solidstate battery composed of this has been evaluated.18 As lithium is more expensive than sodium for the application to commercial battery, the sodium single-ionic conductor should be requested. Furthermore, the redox potential of sodium is similar to that of lithium and costs less.In the present paper, poly[oligo(oxyethylene) methacrylate-co-sodium methacrylate] was prepared as a polymeric solid electrolyte by sodium ionic conduction.
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