Oriented Piezoelectric Poly(Vinylidene Fluoride) Nanofibrous Scaffold Enables Self-Responsive Dendrite Suppression in Solid-State Lithium Metal Batteries

Abstract

Lithium metal batteries (LMBs) are considered promising candidates for next-generation high-energy-density energy storage systems; however, their practical application is severely hindered by uncontrolled Li dendrite growth and unstable interfacial evolution caused by repeated volume fluctuations of Li metal anodes. Herein, we report a piezoelectric solid-state electrolyte by integrating an electrospun poly(vinylidene fluoride) (ESPVDF) nanofibrous scaffold with a macroscopically aligned ferroelectric β phase and a high-dielectric poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE), (PTC)] with a relaxor ferroelectric phase. The three-dimensional interconnected ESPVDF scaffold provides continuous ion-transport pathways, enhanced mechanical strength, and a directionally aligned piezoelectric response, while the high dielectric constant of PTC promotes lithium-salt dissociation and improves ion transport. As a result, ESPVDF-PTC achieves a room-temperature ionic conductivity of 3.0 × 10–4 S cm–1 and a Li+ transference number of 0.25. More importantly, under mechanical stress induced by Li metal volume changes, ESPVDF-PTC generates a transient piezoelectric field through the direct piezoelectric effect, which dynamically regulates Li+ flux, weakens the local electric-field concentration at dendrite tips, and promotes homogeneous Li deposition. Benefiting from this self-responsive dendrite-suppression mechanism, Li//Li symmetric cells based on ESPVDF-PTC electrolyte exhibit stable cycling for more than 1500 h at 0.1 mA cm–2 and 1200 h at 0.2 mA cm–2. Furthermore, solid-state LiNi0.8Co0.1Mn0.1O2 (NCM811)/ESPVDF-PTC/Li full cells deliver an initial capacity of 150 mAh g–1 at 0.5 C and retain 84% of their capacity after 500 cycles. This work provides a new strategy for constructing piezoelectric solid-state electrolytes that dynamically regulate Li+ transport and suppress dendrite growth for stable room-temperature LMBs.