SiC Nanocomposite Electrolyte Membrane with Anchored Anion Sites for Dendrite-Free Solid-state Lithium Metal Battery

Solid-state lithium metal batteries (SSLMBs) have emerged as promising next-generation energy storage systems, distinguished by their superior safety profile and energy density. While polyethylene oxide (PEO)-based solid polymer electrolytes (SPEs) offer notable advantages including inherent safety and manufacturing simplicity, their practical implementation in SSLMBs remains challenged by insufficient ionic conductivity and poor electrode-electrolyte interface compatibility. This investigation presents a dual-stage surface engineering strategy involving the hydroxylation of SiC and the chemical grafting of 3-(trimethoxysilyl)propyl acrylate (TPA) onto hydroxylated SiC nanoparticles, creating SiC-g-TPA hybrid fillers for PEO-based composite electrolytes. The covalent integration of TPA moieties with SiC nanoparticles improved nanofiller dispersion homogeneity within the PEO matrix, effectively suppressing polymer crystallinity while enhancing Li + transport. Furthermore, the engineered SiC-g-TPA architecture leverages abundant surface hydroxyl groups as Lewis acid sites, which synergistically interact with TFSI - anions through hydrogen-bonding. Consequently, both enhanced ionic conductivity of 2.59×10 -3 S cm -1 and an elevated Li + transference number of 0.48 were achieved at 80 °C for the PEO/SiC-g-TPA SPE, along with a wide electrochemical stability window of 5.46 V and stable constant current polarization over 600 h. Assembled LFP//Li cells employing this SPE exhibit a dendrite-free Li metal surface, excellent rate capability and cycling stability with initial discharge capacity of 150.1 mAh g -1 at 0.5 C and 142.9 mAh g -1 at 1 C as well as long cycling life over 200 cycles.