Executive Summary : | Fast ionic solids with liquid-like conductivity near room temperature have garnered attention for the last four decades. Many compounds with high ionic conductivity, comparable to molten salts and aqueous solutions e.g. Li3N, Na--Al2O3, NASICONs, and perovskites have been developed in the past. While these composites exhibit high ionic conductivity in the grain interiors, they could not be applied effectively in the commercial energy storage devices essentially due to high grain boundary impedance (GBI) and poor compatibility with the electrodes. Ever since the development of lithium garnet families (e.g. Li7La3Zr2O12 (LLZO)) with cubic structures, the scientific community has embarked upon the development of all-solid-state batteries (ASSBs) using LLZO for commercial applications. The LLZO has given a hope of realizing all-solid-state, ‘liquid-free’ batteries (ASSBs) in near future. Due to several reasons, e.g. (i) suitable conductivity of the garnets, (ii) much smaller grain boundary impedance, (iii) appreciably wide electrochemical stability window and compatibility with the anode (lithium metal) with lithium, despite competitors like perovskites and NASICON structured Li+ ion systems (e.g. Li1.3Al0.3Ti1.7(PO4)3 i.e. LATP), garnets have attracted the researchers. Electrode-electrolyte (solid-solid) interface is still an issue, that can be resolved using composites of garnets with polymers. While polymer-garnet composites have demonstrated promising performance as electrolytes in all-solid-state batteries, their application in all-solid-state supercapacitors is yet to be explored. Thus the present proposal is planned to carry out studies on fundamental and applied aspects of the garnet-polymer composite membranes/films. One of the motivation is our own recent work (using DST-CRG project) on Li+ NASICON polymer hybrid films, where the conductivity-structure correlation was established mainly using X-ray absorption near-edge structure spectroscopy and impedance spectroscopy. Further, for the first time, all-solid-state supercapacitors with high specific capacitance (≥150 F/g) were developed using a novel lamination route. Using ‘ceramic-in-polymer’ and ‘polymer-in-ceramic’ approaches, polymer-garner hybrid films will be developed in thin membrane and sheet form. The hybrid composites will be characterized in view of conductivity-structure correlation. Furthermore, the garnet-polymer hybrid composites (GPHCs) will be used as electrolyte for thermally and electrochemically stable electric double-layer, pseudo, and hybrid ASSCs. |