A Transformative Molecular Muscle Solid Electrolyte

Solid polymer electrolytes (SPEs) endow Li metal batteries (LMBs) with high expectations, but their real-world applications suffer from the "seesaw effect" between mechanical robustness and ionic conductivity. Herein, inspired by the myofilament sliding, we propose a molecular muscle SPE consisting of mechanically interlocked [c2]daisy chain ([c2]DC) networks (^DCMINs) to break the SPE bottleneck, demonstrating a superior room-temperature (RT) ionic conductivity of 1.04 mS cm^-1 (no plasticizer) without sacrificing the mechanical properties. The dynamic [c2]DC units, in conjunction with host-guest interactions, strengthen the movement of soft poly(ethylene glycol) backbones that coordinate with Li ions to contribute to the improved Li-ion transport compared to the regular cross-linked polymer network. The intrinsically distinctive energy dissipation of ^DCMINs further facilitates the structural integrity of SPEs under the repeated deformation of Li metal anodes, restricting dendrite growth and thus ensuring a lifespan longer than 5000 h for Li symmetric cells. All-solid-state pouch LMBs (∼1 Ah) with muscle-inspired SPEs exhibit competitive performance at RT in terms of cycling stability (87.8% capacity retention after 750 cycles for the LiFePO₄ cell). We anticipate that our findings could spur investigations regarding high-performance SPE design for advanced solid-state batteries.