High-Performance Transparent Solid Polymer Electrolyte Based on Copolymer of Deep Eutectic Electrolyte and Methyl...

Polymerizable deep eutectic electrolytes (PDEEs) have emerged as next-generation electrolytes for electrochemical devices, addressing the leakage risk of traditional DEEs and the safety concerns of flammable ionic liquid electrolytes. However, a significant challenge hindering further development is the scarcity of DEE-based polymers capable of simultaneously balance the electrolyte conductivity, mechanical strength, and stability. Herein, a high-performance poly(DEEs) was engineered by exploiting the synergistic effects of hydrogen bonding and ion-dipole interactions via the incorporation of acrylamide (AM), succinonitrile, LiClO₄, and methyl methacrylate (MMA). The solid polymer electrolytes were elaborately designed via in situ copolymerization, facilitating Li⁺ transport through hydrogen bond interaction with NH₂ and C≡N groups, and utilizing the dual-skeleton framework of AM and MMA to integrate electrochemical and mechanical properties. The optimized poly(DEE-MMA) exhibits a high ionic conductivity of 1.43 mS cm^-1, a superior Li⁺ transference number of 0.83, and excellent tensile strength of 17.8 MPa at 298 K, enabling the Li||LiFePO₄ battery to deliver an impressive lifespan of 120 cycles with 83% capacity retention and the electrochromic device sustains 2000 coloration-bleaching cycles with retaining 80% of the initial optical modulation. These findings provide a novel strategy for high-performance solid polymer electrolytes and demonstrate potential applications in electrochemical devices.