(401d) Cyclic Carbonate Plasticizers to Improve Li-Ion Conductivity in Solid Polymer Electrolytes

Solid polymer electrolytes (SPEs) have been the focus of study for decades to address general problems in lithium-ion batteries, such as thermal runaway by removing volatile solvents, uncontrolled mass transport by immobilizing anions to the polymer matrix, undesired side reactions, and lithium dendrite growth by providing a mechanical barrier. Unfortunately, SPEs suffer from poor lithium-ion mobility and conductivity due to the stationary phase of immobilized anions, poor ion pair dissociation, and the slower time scales of polymer diffusivity compared to liquid electrolytes. The focus of this investigation is on improving the conductivity of SPEs, with and without immobilized anions, through the use of organic carbonate-based plasticizers to improve Li-ion dissociation and diffusion. Several solid plasticizer compounds were chosen to avoid highly flammable, liquid plasticizers that harbor the same safety concerns as conventional liquid electrolytes. Studies varying the carbonate structures, the concentration within the SPEs, and the SPE structure were characterized by impedance spectroscopy and coin cell cycling to observe their effect on improving Li-ion conduction.