(Invited) Pragmatic Approach and Challenges of All Solid State Batteries: Hybrid Solid Electrolyte for Technical Innovation

Abstract

For the growth of electric vehicle market, lithium-ion batteries (LIBS) used in the EVs still requires safety and reliability. Unfortunately, large-scale application of the LIBs is being challenged due to the fact that the use of flammable liquid electrolytes has caused safety issues such as leakage and fire explosion. In this respect, all-solid-state batteries (ASSBs) have been intensively studied to ensure the safety and mileage that are superior to the current LIBs. In terms of solid electrolytes, oxide electrolytes not only shows high ionic conductivity (10-4 ~ 10-3 S/cm) but also high mechanical strength to suppress surface dendrite formation. In addition, the oxide electrolytes possess advantages such as non-flammability, high thermal stability, and excellent electrochemical stability (~ 6 V), enabling high temperature/high voltage operations of oxide-based ASSBs. However, most of oxide materials require a sintering process at high temperatures to form a planar solid electrolyte. And a lack of flexibility results in non-uniform electrolyte/electrode contact in the battery, which makes it difficult to apply the rigid oxide electrolyte directly. On the other hand, solid polymer electrolytes have also been actively investigated due to no leakage, good electrolyte/electrode contact, easy processing, flexibility, and good film formability. However, the solid polymer electrolytes have critical disadvantages such as low ionic conductivity at room temperature and low thermal/mechanical stability, which precludes commercialization of solid polymer-based ASSBs despite their advantages. To overcome each disadvantages of oxide and polymer electrolytes, we developed hybrid electrolytes for improved ionic conductivity, easy processing, and formation of continuous electrolyte/electrode interface. In this presentation, pragmatic approach and current challenges related to solid batteries will be discussed including innovative manufacturing process. Hybrid electrolytes and their synergistic effect on the battery performance as a promissing solution will be presented [Fig. 1]