Ricerc@Sapienza

This proposal presents a novel hybrid electrolyte based on oxide-based solid electrolytes (OSEs) and ionic liquids (ILs). The aim of this hybridization is to reduce the grain boundary resistances of OSEs. Solid electrolytes are promising materials which no doubt improve safety of lithium ion batteries. Especially OSEs are recognized as air-stable electrolytes compared to sulfide-based solid electrolytes. However, their high ionic conductivity is achieved solely after sintering processes under high temperatures. In this study, ILs composed of organic ions are chosen as a partner for OSEs. The integration with organic materials will improve the flexibility of OSEs in terms of the multifariousness of ionic conductivity, the diversity of material design, and the variation in the structure of resulting batteries.

Taking into account the advantages of organic chemistry, ILs will be suitably functionalized and added to OSEs in two ways: (1) as macro-binders between OSE particles and (2) as nano-binders in OSE glasses. In the (1) case, we intent to form IL coatings on OSE particles to suppress their grain boundary resistance and achieve the ionic conductivity higher than 1.0 mS/cm. The coatings will be immobilized by improving the compatibility between OSEs and ILs, which will be undertaken through the insertion of functional moieties to the ILs such as halide anions, polar groups, and lithium salts. In the (2) case, ILs will be included in the glass structures of OSEs, thus the possibility of IL bleed-out will be minimized. This is a heretofore untried novel approach for the design of solid lithium ion conductors. The ceramic formations of inorganic-organic hybrids will be attempted by taking both the contributions of Van der Waals interactions of organic moieties and Coulombic interactions of ionic moieties. To this end, we intend to propose stem materials which are designed and can be functionalized based on the dual concept of organic and inorganic chemistry.