Deep Eutectic Solvent (DES)-based Electrolytes for Nanomaterials-based Supercapacitors

The theoretical energy and power of supercapacitors is determined by their capacitance, working voltage window, and conductivities of electrode materials/electrolytes as a function of temperature. With recent advances in nanomaterials-based electrodes, the performance of supercapacitors is mainly limited by the electrolytes. Current supercapacitors use flammable organic electrolytes that are un-safe and have limited low and high temperature storage/operation. Therefore, a safe cost-effective electrolyte with high conductivity and wide voltage windows over wide operational (-45°C to +65°C) and storage (-55°C to +75°C) temperature ranges is needed for next-generation supercapacitors. In the Phase I study, Lynntech has successfully developed low-cost deep eutectic solvent (DES) based electrolytes with non-flammability, high ionic conductivity, low viscosity, and large electrochemical stability window over the target temperature range. Preliminary DES-based coin cell supercapacitors exhibit high specific capacitance before and after storage at very low temperatures required by the Army, which successfully demonstrated the feasibility of DES-based electrolytes for supercapacitor application. During Phase II, Lynntech will develop and evaluate prototype supercapacitors based on the optimal electrolytes and graphene-based electrodes, and deliver prototypes to the Army for validation. The large scale synthesis of electrolytes and electrode materials will also be explored.