Dual‐Scale Steric‐Topological Engineering of Polymer Electrolytes for Solid‐State Lithium Metal Batteries

ABSTRACT Solid‐state polymer electrolytes (SPE) are often constrained by an intrinsic trade‐off between room‐temperature ion transport and the mechanical/interfacial stability required to suppress lithium dendrites. Here, a dual‐scale steric‐topological engineering strategy is proposed to resolve this issue. By constructing a composite SPE (PBPL) in which an amorphous 3D crosslinked network, generated in situ from bis(vinylsulfonyl)methane and pentaerythritol tetraacrylate, is embedded within a poly(vinylidene fluoride‐co‐hexafluoropropylene) matrix. Supported by theoretical calculations and finite‐element simulations, this hierarchical design couples anion regulation with interfacial mechanics across two length scales. At the molecular scale, bulky sulfonyl moieties impose selective steric and coordinative constraints on TFSI ⁻ , reducing anion mobility, reconstructing the Li ⁺ coordination environment, suppressing ion aggregation, and promoting effective salt dissociation. At the network scale, the rigid crosslinked framework suppresses polymer relaxation and homogenizes interfacial stress and local electric‐field distributions, thereby stabilizing Li plating/stripping and mitigating dendrite initiation. Consequently, PBPL achieves a room‐temperature ionic conductivity of 0.77 mS cm ⁻¹ and a Li ⁺ transference number of 0.52. Full cells exhibit durable cycling with 93% capacity retention after 250 cycles in Li||PBPL||LiFePO ₄ and 85% retention after 170 cycles in Li||PBPL||LiNi _0.8 Co _0.1 Mn _0.1 O ₂ . This work demonstrates that dual‐scale steric‐topological engineering serves as a practical paradigm for developing high‐performance SPE.