Development and characterization of novel fast charge transferring polymer electrolyte materials

The increasing industrialization, technological advancements, and economic growth in developing countries have significantly improved the demand for energy. In this context, energy storage and energy-generating systems have become crucial research topics, with the development of electrolytes providing high ionic conductivity for lithium-ion batteries (LIBs) being of particular importance. Within the scope of this thesis, different approaches were employed to achieve this objective, including (i) solid polymer electrolytes (SPE), (ii) gel polymer electrolytes (GPE), and (iii) composite polymer electrolytes (CPE). In addition to polymer electrolyte preparation, the characterization of these electrolytes was performed and the relationship between free volume and ionic conductivity were investigated. In the design of fast ion-conducting electrolytes developed in this thesis, the first approach involved the preparation of SPEs by incorporating different ratios of LiClO4 into the PVdF-HFP/PMMA blend matrix. The effects of these compositions on structural, thermal, mechanical, morphological, ionic conductivity, and free volume properties were examined. In the second approach, two different methodologies were adopted for preparing GPE films. In the first method, various lithium salts (LiPF6, LiTFSI, LiClO4, LiTf, LiBF4) were incorporated into the polymer matrix using EC and commercial EC-DMC as plasticizers, and their effects on the aforementioned properties were evaluated. Additionally, GPE films were obtained by varying the percentage of plasticizer in the electrolyte composition. In the other method of second approach, four different ionic liquids (EMIMTFSI, BMPTFSI, EMIMBr, and EMIMCH3SO3), possessing different cations and anions, were added into the polymer blend in various ratios, and their physicochemical, morphological, thermal, mechanical, ionic conductivity and free volume properties were investigated in relation to lithium salt usage. In the third approach, based on the results of the first two approaches, a model film was selected, and the effect of TiO2 incorporation as an inorganic filler on the aforementioned properties was explored. The comparative findings obtained in this thesis are expected to contribute to the scientific and industrial development of electrolyte preparation studies, which are crucial for energy storage and generation systems.