Composite solid-state electrolyte from waste modacrylic fibers with multiple Li+ transport channels and enhanced interfacial stability for lithium metal batteries

Abstract

The textile industry accounts for 5–10 % of global greenhouse gas emissions, with its production and disposal processes exacerbating environmental degradation through microplastic pollution and unsustainable resource consumption. Addressing this critical challenge, we present a breakthrough strategy for upcycling post-consumer modacrylic textiles into high-performance composite solid electrolyte (CSE). The developed CSE exhibits exceptional ionic conductivity of 8.5 × 10⁻⁴ S·cm⁻¹ at 30 °C and an outstanding lithium-ion transference number of 0.84 at 50 °C. The acrylonitrile (AN) and vinyl chloride (VC) segments in modacrylic fibers play distinct functional roles: AN segments confer a high dielectric constant, superior oxidative stability, and robust coordination with lithium salts; Concurrently, VC components enhance thermal stability and facilitate the formation of a stable solid electrolyte interphase (SEI) through CCl with Li⁺ dipole interactions. Density functional theory (DFT) and molecular dynamics (MD) simulations elucidate three synergistic ion-transport mechanisms within the three-dimensional (3D) polymer matrix. Electrochemical performance demonstrates remarkable interfacial compatibility with lithium metal: Li/Li symmetric cells maintain stable cycling for >3500 hours at 0.1 mA·cm⁻². Practical applicability is evidenced by LiFePO₄/Li cells retaining 99.1 % capacity after 100 cycles at room temperature. Furthermore, LFP/Li pouch cells demonstrate outstanding mechanical flexibility and stable operation under bending and folding conditions. This work establishes a circular "waste-to-energy" paradigm through molecular reengineering of textile waste. The proposed methodology expands the repository of bio-derived polymer electrolytes, advances high-value waste upcycling, and provides critical insights for developing commercially viable solid-state lithium metal batteries (SSLMBs) with enhanced safety and energy density.