Relieving Rather Than Blocking: A Slide‐Crosslinked Polymer Electrolyte for Dendrite‐Free Lithium Metal Batteries

ABSTRACT The development of high‐performance lithium metal batteries relies on solid polymer electrolytes (SPEs) that combine high ionic conductivity with superior interfacial stability. Conventional crosslinked SPEs often suffer from rigid networks that fail to accommodate the volume fluctuations of lithium metal during cycling. Inspired by the mechanically interlocked “molecular pulley” architecture of polyrotaxanes (PRs), we developed a slide‐crosslinked SPE (PR‐PVC) via in situ polymerization. This unique architecture facilitates dynamic stress dissipation, significantly improving interfacial adaptability and stability. Through systematic optimization of the PR molecular structure and electrolyte composition, we elucidated key structure‐property relationships and identified an optimal formulation. The resulting electrolyte exhibits exceptional ionic conductivity (2.61 mS cm ⁻¹ ), a high lithium‐ion transference number (0.89), and robust mechanical properties (3.4 GPa). When integrated into Li//LFP cells, it delivers stable cycling performance with 81.1% capacity retention after 500 cycles. This work offers a promising strategy for designing next‐generation high‐energy‐density batteries.