High performance of solid electrolyte endowed by SiO₂ cross-linking agent towards lithium metal battery

A dual network solid polymer electrolyte is prepared, the cross-linked part is constructed using ring-opening polymerization reaction, in which SiO₂ particles connect with polyethylene glycol diglycidyl ether (PEGDE) and polyetheramine (PEA) as cross-linking point. The introduction of SiO₂ is conducive to reduce the crystallization of polymer matrix, improve the strength and promote the fast migration of Li ions. The abundant C-O segments in PEGDE and PEA are advantageous to the hopping behavior of Li ions and improve the ionic conductivity of electrolyte. Poly (vinylidenefluoride-hexaflouropropylene) (PVDF-HFP) is selected as linear part due to its robust mechanical behavior and outstanding electrochemical property. The obtained SiO₂ functionalized PEGDE and PEA-PVDF-HFP solid polymer electrolyte (referred to as SGPP-ASPE) demonstrates excellent ionic conductivity of 2.4 × 10⁻⁴ S cm⁻¹, high lithium-ion transference number of 0.54 and minor interfacial polarization of 0.09 V after 1000 h using Li//Li symmetrical cell. After assembling Li/LiFePO₄ cell, a favorable cycling stability with the capacity retention of 93.8% after 100 cycles at 0.2 C is delivered. The reasonable design of advanced polymer electrolytes with dual network opens up a new path for the development of solid high-performance LMBs.