Chloride‐Enhanced High‐Strength Polymer Electrolyte for Lithium‐Metal Batteries

Abstract Polymer‐based electrolytes have emerged as attractive candidates for solid‐state batteries owing to their facile processability, excellent interfacial compatibility, and cost‐effectiveness. However, their excessive crystallinity, disrupted ion pathways, and inadequate mechanical performance directly impair ionic conductivity and cycling stability. Herein, a synergistic strategy is reported to simultaneously incorporate LiCl and ZrCl ₄ in a poly (ethylene oxide)/poly (vinylidene fluoride) (PEO/PVDF) electrolyte matrix to achieve enhanced structural and electrochemical properties. The introduction of LiCl and Lewis‐acidic ZrCl ₄ increased the lithium‐ion transference number to 0.56 and promoted the formation of a stable, LiF‐ and LiCl‐rich electrolyte interphase layer on the lithium anode. The symmetric cells exhibited a critical current density of 3.1 mA cm ⁻² and demonstrated stable cycling for over 400 h at a current density of 0.7 mA cm ⁻² , and full cells paired with LiFePO ₄ cathode (3.8 mg cm ⁻² ) retained 88.4% of their initial capacity after 1000 cycles. The electrolyte exhibits a tensile strength of 12 MPa with an elongation of 210%, achieving an excellent balance between mechanical strength, flexibility, and processability. This dual‐filler strategy provides a practical and effective approach for enhancing polymer electrolyte performance and holds great promise for broad applications in solid‐state lithium batteries.