Macroscopically Ordered Piezo-Potential in All-Polymetric Solid Electrolytes Responding to Li Anode Volume Changes...

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_0.8Co_0.1Mn_0.1O₂ (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.