Metal-Organic Framework-Derived Elastic Solid Polymer Electrolytes Enabled by Covalent Crosslinking for High-Performance Lithium Metal Batteries

Abstract

The key issue in utilizing solid polymer electrolytes for high-energy-density lithium metal batteries is to balance the conflicting demands of superior processability, adequate ionic conductivity, and mechanical stability. Inspired by molecular structure design, a metal-organic framework-derived polyether poly(urethane urea) solid polymer electrolyte (denoted as ePU@H SPE) has been synthesized via a facile polycondensation method involving covalent crosslinking. The reduced crystallinity and numerous polar groups in ePU@H SPEs enhance Li salt dissociation and create efficient Li⁺ ion diffusion channels, yielding remarkable ionic conductivity (1.48 × 10⁻⁴ S cm⁻¹). The polymer backbones, incorporating covalent bonds and dynamic hydrogen bonds, provide superb mechanical strength (5.12 GPa), high toughness (1240%), and excellent resilience, which suppress lithium dendrite growth and buffer electrode volume fluctuations during cycling. Leveraging these attributes, the well-designed ePU@H SPE enables ultra-high durability in lithium plating/stripping over 2300 h. Moreover, the integrated LFP|ePU@H|Li batteries, generating delicate electrode/electrolyte interfacial contact, deliver an exceptionally long lifespan (86% retention over 500 cycles at 1 C). Moreover, the LFP|ePU@H|Li pouch cell operates reliably even under severe deformation and external damage. Impressively, the stable cycling performance of full batteries incorporating high-voltage LCO and high-capacity S cathodes further verifies the significant potential of advanced ePU@H SPEs for practical applications.