Room temperature ionic liquids transport number

Room-temperature ionic liquids (RTILs) are intrinsic ionic conductors which have been successfully employed as nonflammable/nonreactive electrolytes in a range of electrochemical devices, including dye-sensitized solar cells [1,2], lithium batteries [3], fuel cells [4], and supercapacitors [5]. The quantification of mass transport is of interest in any solvent, particularly those employed in electrochemical devices, as it affects the ultimate rate/speed at which the device can operate. The diffusivity or diffusion coefficient (D) of a redox active species, along with other thermodynamic parameters such as the bulk concentration (c) and the stoichiometric number of electrons (n) that are of fundamental significance in any study of an electrode reaction, can be determined experimentally using a range of electroanalytical techniques [6], As with any analytical method, the ideal electroanalytical technique for parameter characterization should be accurate, reproducible, selective, and robust. In many respects voltammetric methods meet these requirements, since they can be... 

The concept of SPE dates back to 70s, when Armand firstly proposed a new ion conductor based on a lithium salt properly complexed by a polar and aprotic polymer matrix without the use of any liquid component (additives or liquid electrolytes) [65]. At the beginnings, the research on SPEs was exclusively focused on poly(ethyleneoxide) (PEO) as the complexing polymer [66]. Ever since, a lot of polymer/salt systems were deeply investigated, such as those based on PMMA, PAN, PVDF [66-69]. In principle, SPEs must satisfy some basic requirements (i) ionic conductivity higher than 10 " S/cm at room temperature, (ii) good thermal, chemical and mechanical stability, (iii) lithium transport number close to the unity, and (iv) compatibility with the electrodes and consequently wide electrochemical windows [67]. 

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