Akihiro Noda

Highly conductive polymer electrolytes prepared by in situ polymerization of vinyl monomers in room temperature molten salts

In order to achieve highly conductive polymer electrolytes, room temperature molten salts with high ionic conductivity have been explored, and in situ polymerization of vinyl monomers in the molten salts have been conducted. It is found in this study that 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and 1-butylpyridinium tetrafluoroborate (BPBF4) form room temperature molten salts, and these molten salts exhibit high ionic conductivities of 2×10−2 and 3×10−3 S cm−1 at 30°C, respectively. Certain vinyl monomers can be polymerized in the molten salts by radical polymerization. In situ polymerization of suitable vinyl monomers gives transparent, mechanically strong and highly conductive polymer electrolyte films. For example, 2-hydroxyethyl methacrylate network polymers in which BPBF4 is dissolved exhibit an ionic conductivity of 10−3 S cm−1 at 30°C.

Brønsted acid-base ionic liquids and their use as new materials for anhydrous proton conductors.

Novel Brønsted acid-base ionic liquids, derived from a simple combination of a wide variety of organic amines with bis(trifluoromethanesulfonyl) amide are electroactive for H2 oxidation and O2 reduction at a Pt electrode under non-humidifying conditions, which shows the prospect of the use of protic ionic liquids as new materials for anhydrous proton conductors at elevated temperatures.

XPS study of lithium surface after contact with lithium-salt doped polymer electrolytes

Abstract X-ray photoelectron spectroscopy (XPS) is used to probe the surface layer and element composition of Li-metal electrodes before and after contact with polymer electrolytes containing LiN(SO 2 CF 3 ) 2 (LiTFSI) or LiBF 4 . Native film on as-received metallic lithium was composed of Li 2 CO 3 /LiOH in the outer layer and Li 2 O in the inner layer. LiF was formed during lithium contact with electrolyte due to reaction between the native film and impurities in the electrolyte. The polymer electrolyte containing LiTFSI yielded a very thin film with limited porosity in the inner layers, which was reflected in the limited amplitude dependence of complex impedance spectra. LiBF 4 mixed with polymer resulted in a thicker film with high porosity, as was postulated from the greater influence of the amplitude of the oscillation level.