Ion Conductor Design for All-Solid-State Lithium Batteries and Alkaline Fuel Cells

Climate change, driven by the burning of fossil fuels, remains one of the greatest global challenges. To reduce emissions while maintaining modern living standards, a rapid transition to renewable energy is essential. However, this shift is constrained by limitations in current energy storage technologies. The intermittency of renewable sources, growing electrification of transportation, and widespread use of electronic devices underscore the urgent need for next-generation electrochemical systems, such as lithium-ion batteries (LIBs) and fuel cells. In conventional LIBs, carbonate-based liquid electrolytes pose safety risks due to their flammability and volatility. Solid-state electrolytes offer improved thermal stability but often suffer from low ionic conductivity at room temperature. To address this, a novel electrolyte composed of a tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) charge-transfer (CT) complex and lithium bis(trifluoromethylsulfonylimide) (LiTFSI) was developed. The system demonstrates fast ion transport facilitated by trace water, which promotes salt dissociation, and thermal annealing, which enhances interfacial interactions. A composition with a 1-1-2-0.45 molar ratio of TTF-TCNQ-LiTFSI-H2O achieves an ionic conductivity of 2 × 10?³ S/cm at 25 °C. To evaluate the broader applicability of CT complexes, TTF-TCNQ was integrated into various polymer matrices and salts. Across all systems, ionic conductivity increased markedly. In addition to batteries, this work explores new anion exchange membranes (AEMs) for intermediate-temperature fuel cells. A novel synthetic approach using Friedel–Crafts hydroxyalkylation yields block copolymer membranes with microphase-separated morphology and strong alkaline stability. These membranes show high conductivity (67 mS/cm at 80 °C) and retain structural integrity after prolonged alkaline exposure.