Macroscopically Ordered Piezo‐Potential in All‐Polymetric Solid Electrolytes Responding to Li Anode Volume Changes for Dendrites Suppression

Abstract Solid‐state polymer electrolytes (SPEs) address the safety issue of lithium‐metal batteries but fail to resolve dendrite growth caused by anode volume fluctuations. Piezoelectric poly(vinylidene‐co‐trifluoroethylene) [P(VDF‐TrFE)] nanofiber interphases with aligned dipoles are developed that generate macroscopically directional electric fields during lithium expansion. Strategically orienting the piezoelectric field against Li ⁺ migration redirects deposition from dendrite tips to planar regions through potential gradient steering. This approach enhances lithium salt dissociation while suppressing anions movement, achieving both high ionic conductivity (5.0 × 10 ⁻⁴ S cm ⁻¹ ) and Li ⁺ transference number (0.40). Symmetric Li cells achieve 3000 h stability at 0.2 mA cm ⁻² and 25 °C, surpassing non‐piezoelectric SPEs by 750%. LiNi _0.8 Co _0.1 Mn _0.1 O ₂ (NCM811)//Li full cells retain 96% capacity after 400 cycles at 0.5 C. Crucially, reversing the orientation direction of the piezo‐electric field nullifies these benefits, proving that the direction of the piezoelectric field, not mere piezoelectricity, governs dendrite inhibition. This work introduces a novel strategy for inhibiting dendrite growth by leveraging the directionally engineered piezoelectric field of polymers.