Rational Design of Organic–Inorganic Interface Ion Transport Pathways in Metal–Organic Framework Modified Solid Electrolytes

All-solid-state lithium–metal batteries (ASSLMBs) that employ poly(ethylene oxide) solid polymer electrolytes (PEO-SPEs) exhibit the potential for attaining high energy densities. However, compared with other solid electrolytes, they present challenges such as low ionic conductivity, limited electrochemical windows, and reduced stability at even higher temperatures. Here, applying zeolitic imidazolate framework-8 (ZIF-8)-modified Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) as a functional filler, a LATP@ZIF-8 composite solid electrolyte (CSE) is prepared with poly(ethylene oxide) (PEO). The ZIF-8 shell serves as an interfacial bridge to address key issues of PEO-based electrolytes: filler agglomeration, poor compatibility, anion migration, and discontinuous ion transport. This interface engineering strategy, realized through filler surface functionalization, enhances the performance of composite solid-state electrolytes, paving the way toward safer, higher-energy-density batteries. Its porous structure and Lewis acid centers not only promote the dissociation of the lithium salt LiTFSI but also effectively immobilize the TFSI – anion, thereby increasing the lithium-ion transference number to 0.62. The obtained electrolyte, when characterized by EIS, achieved an ionic conductivity of 3.04 × 10 –4 S cm –1 at 60 °C, demonstrating a low activation energy of 0.22 eV. When configured in a Li||CSE||LFP assembly, the cell delivers an initial discharge capacity of 146.8 mAh g –1 and retains over 81% of the initial capacity after 400 cycles at 1 C and 60 °C, confirming its exceptional cycling durability.