Superionic Conductors: Solid-State Energy Storage and Conversion

Superionic conductors (SICs) are an intriguing class of materials that possess marvelous ionic conductivity and thermoelectric properties, holding great promise for next-generation energy storage and conversion devices. The present dissertation focuses on three issues of SICs in solid-state energy storage and conversion applications: (1) the development of an all-solid-state rechargeable battery based on a superionic ceramic conductor, (2) the investigation of the effect of relative humidity (RH) on the reaction kinetics in rubidium silver iodide (RbAg₄I₅) based all-solid-state battery, (3) the realization of a thermally chargeable all-solid-state supercapacitor using a superionic ceramic conductor.

RbAg₄I₅ owing to its unprecedented ionic conductivity (>0.2 S cm^-1 at room temperature) and high stability in a wide temperature range (0-100°C), is an ideal candidate for being used as an electrolyte material in solid-state batteries. The first part of the dissertation presents a novel rechargeable all-solid-state battery utilizing the high ionic conductivity of RbAg₄I₅ and conductive adhesive-based electrodes. The second part of the dissertation is the systematic study of the effect of RH on the reaction kinetics at the Ag/RbAg₄I₅ anode and graphite/RbAg₄I₅ cathode using three-electrode cells. The third part of the dissertation demonstrates a novel thermally rechargeable all-solid-state supercapacitor based on the ionic thermoelectric (Soret) effect comprised of superionic RbAg₄I₅ solid electrolyte and graphite/RbAg₄I₅ composites electrodes.