Crosslinking Density and Salt Addition Impacts on the Large Amplitude Oscillatory Shear Response of Acrylate Network Electrolytes

ABSTRACT Solid‐state polymer electrolytes (SPEs) are promising alternatives to liquid electrolytes for lithium‐ion batteries, offering improved safety and mechanical stability. Poly(ethylene oxide) (PEO)‐based electrolytes have been widely studied, but their ionic conductivity is often limited by crystallinity and the modulus in molten state is reduced. Crosslinked polymer networks incorporating ethylene oxide (EO) chains can provide a balance between mechanical robustness and ion transport by suppressing crystallinity while maintaining conductivity. Here, we report the synthesis and characterization of acrylate network electrolytes incorporating EO side chains. The networks were prepared via white‐light‐initiated polymerization using acrylates with three EO repeat unit side chains and diacrylates with 12 EO repeat units as crosslinkers, with varying crosslink densities (2–6 mol%). Rheological analysis revealed a distinctive behavior for dry networks, showing a pronounced loss modulus overshoot () in the LAOS regime. In neutral networks, increasing crosslink density amplified the overshoot which occurred at lower strains () due to network stiffening. However, in salt‐containing networks increased with crosslink density due to transient ionic crosslinks enhancing strain tolerance. Impedance measurements revealed a tradeoff between crosslinking and ionic conductivity, with the 2% crosslinked network achieving high conductivity. The addition of propylene carbonate further enhanced conductivity while maintaining mechanical integrity. These findings highlight the tunability of acrylate‐based network electrolytes for ion transport and non‐linear response to strain.