Unraveling the Synergistic Coupling Mechanism of Li+ Transport in an “Ionogel‐in‐Ceramic” Hybrid Solid Electrolyte for Rechargeable Lithium Metal Battery

Abstract Understanding the ionic transport behaviors in hybrid solid electrolytes (HSEs) is critically important for the practical realization of rechargeable Li‐metal batteries (LMBs) with high safety. Herein, it is reported a new solid “Ionogel‐in‐Ceramic” electrolyte by using the Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) ceramic particles as a framework and “Poly(ionic liquid)s‐in‐Salt” (“PolyIL‐in‐Salt”) ionogel as an ionic bridge via a simple pressing process. The “PolyIL‐in‐Salt” ionogel precursor is designed to improve the chemical compatibility at solid–solid interfaces. Molecular dynamics simulations reveal the roles of salt concentrations on the distribution of co‐coordination of “PolyIL‐in‐Salt” ionogel. Moreover, the “PolyIL‐in‐Salt” ionogel containing co‐coordination not only inhibits the parasitic reactions between LATP and Li anode but also provides efficient Li + conducting pathways. Benefiting from the designed structure, the “Ionogel‐in‐Ceramic” HSE exhibits an excellent ionic conductivity of 0.17 mS cm −1 at 50 °C. Meanwhile, the as‐formed solid electrolyte enables a long cycle of over 3500 h in Li/Li symmetric cell. Further, all‐solid‐state lithium metal batteries fabricated on LiFePO 4 and high voltage LiCoO 2 cathodes deliver 160.0 mAh g −1 , 125.0 mAh g −1 , respectively. This study sheds light on the rational design of solid‐state electrolytes with efficient interparticle Li + conduction, compatible, stable, compact, and durable electrode–electrolyte interfaces.