Advancements in Quasi-Solid-State Li Batteries: A Rigid Hybrid Electrolyte Using LATP Porous Ceramic Membrane and Infiltrated Ionic Liquid

Despite the progress made in Li-ion battery components, technology still faces major challenges. Among them, the development of novel electrolytes with promising characteristics is required for next-generation energy storage devices. In this work, rigid hybrid electrolytes have been prepared by infiltration of an ionic liquid solution (Pyr₁₄TFSI) with a lithium salt (LiTFSI) into a sintered LATP ion-conducting porous ceramic. The porous ceramic 3D network was obtained via solid-state sintering of LATP powders mixed with a small amount of corn starch as pore former. A synergetic effect between the ionic liquid and support was evidenced. The resultant quasi-solid-state hybrid electrolytes exhibit high ionic conductivity (∼10^-3 S·cm^-1 at 303 K), improved ion transfer number, t_Li+, and a wide electrochemical window of 4.7-4.9 V vs Li⁺/Li. The LATP porosity plays a critical role in the free Li⁺ charge because it favors higher TFSI^- confinement in the ceramic interfaces, which consequently positively influences t_Li+ and ionic conductivity. Electrochemical tests conducted at room temperature for Li/LiFePO₄ cells using the hybrid electrolyte exhibited a high capacity of 150 mAh·g^-1_LFP at C/30, and still retained 60 mAh·g^-1_LFP at 1 C, while bare LATP does not perform well at low temperatures. These findings highlight this hybrid electrolyte as a superior alternative to the ceramic LATP electrolyte and a safer option compared with conventional organic electrolytes.