Directionally Aligned “Mechanical Balance” Design Enables Near-Frictionless Li ⁺ Transport in Polymer Electrolytes

Polymer electrolytes hold promise for lithium metal batteries due to their facile processability and superior electrode interfacial compatibility but suffer from intrinsically low ionic conductivity due to strong Li⁺-polymer interaction and tortuous ion transport pathways. Inspired by the principle of "mechanical balance (MB)" in physics, we propose a paradigm-shifting strategy involving constructing an MB zone, in which an opposing force from anchored anion clusters is introduced to counteract the strong Li⁺-polymer interaction, dramatically reducing Li⁺ decoupling energy barriers. Furthermore, these MB zones are directionally aligned by integrating a designed fluorinated graphene/zeolitic imidazolate framework-8 (FG/ZIF-8) scaffold with in situ-polymerized 1,3-dioxolane, enabling near-frictionless and short-distance Li⁺ transport. The resulting electrolyte achieves an exceptional ionic conductivity of 1.2 mS cm^-1 at 25 °C and an impressive Li⁺ transference number of 0.71. The assembled Li|LiFePO₄ cells deliver unprecedented rate capability of 97.7 mAh g^-1 at 8C, and an ultralong cyclability with 81% capacity retention after 3500 cycles at 4C. Notably, the electrolyte also demonstrates excellent compatibility with a high-voltage LiNi_0.5Co_0.2Mn_0.3O₂ cathode and outstanding safety/cycling performance in practical pouch cells. This work pioneers a universal MB paradigm for designing advanced polymer electrolytes with superior ionic conduction toward high-performance quasi-solid-state batteries.