Synergistic Li ₃ Sb/LiF Hybrid Networks in Poly(Tetrahydrofuran) Electrolyte for High‐Performance Solid‐State Lithium Metal Batteries

ABSTRACT

The practical deployment of solid‐state lithium metal batteries (SSLMBs) remains hindered by unfavorable interfacial durability and sluggish Li ⁺ transport. Here, a Li ₃ Sb/LiF‐embedded composite polymer electrolyte (SF@PF) with a thickness of ∼5 µm was fabricated via an in situ strategy. The precursor SbF ₃ can not only coordinate with propylene oxide (PO) to activate the cationic ring‐opening polymerization, but also spontaneously react with Li metal to produce uniformly dispersed Li ₃ Sb alloy and LiF nanoparticles within the poly(tetrahydrofuran) (PTHF) matrix. In this hybrid network, Li ₃ Sb with favorable kinetics facilitates Li‐ion transport, while LiF as an electron‐blocking layer suppresses dendrite growth and parasitic reactions. This approach eliminates the need for pre‐synthesized inorganic fillers while achieving an ionic conductivity (2.5 × 10 ⁻⁴ S cm ⁻¹ at room temperature) and a Li ⁺ transference number (0.68). LiFePO ₄ full cells retain 88.1% capacity after 500 cycles at 1 C and deliver improved performance at rates up to 5 C. Pouch cells also exhibit steady cycling under folded deformation.