Oxide-Based Semi-Solid-State Hybrid Electrolyte for High Performance Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are widely used in mobile electronics and electric vehicles, as a reliable energy storage source. Recently, the demand for LIBs with high energy density and enhanced safety has increased. A semi-solid-state electrolyte can enhance the battery safety by immobilizing flammable liquid electrolyte and improve the cycling performance by suppressing the side reactions of electrolyte. However, its low ionic conductivity has been a main technical hurdle for the development of LIBs with good cycling performance. In this work, we prepared the highly conductive semi-solid-state hybrid electrolytes incorporating oxide-based inorganic electrolyte. To fabricate them, a porous membrane composed of poly(vinylidene fluoride-co-hexafluoropropylene) and fibrous Li_6.4La₃Zr₂Al_0.2O₁₂ (LLZAO) was prepared. The porous membrane was immersed in the electrolyte solution containing cross-linking agent, followed by thermal curing to obtain a free-standing film. The obtained hybrid electrolyte exhibited high ionic conductivity, high Li⁺ transference number, and enhanced thermal stability. The lithium-ion cells composed of graphite anode, semi-solid-state hybrid electrolyte, and LiNi_0.8Co_0.1Mn_0.1O₂ cathode showed high initial capacity and superior cycling performance compared to the cell employing liquid electrolyte.