Interfacial Polarization Engineering via One-Dimensional Ionic Crystal Fibers for High-Performance Triboelectric and Piezoelectric Nanogenerators.

Enhancing the dielectric properties of polymer composites through particulate inorganic fillers 0D has been widely explored as an effective strategy to improve the energy-harvesting performance of triboelectric and piezoelectric devices. Compared with conventional particulate fillers, 1D fillers offer intrinsic structural anisotropy and enlarged polymer-filler interfaces that favor interfacial polarization and charge transport. However, the intrinsically isotropic crystallization behavior of inorganic salts hinders the formation of long-range ordered 1D structures, leaving one-dimensional inorganic salt fibers largely unexplored as functional fillers. Here, we propose a template-guided directional crystallization strategy to construct 1D potassium chloride (KCl) fibers as functional fillers. The resulting fibers reach macroscopic lengths of up to ∼6 cm and retain continuous crystalline morphology within polymer matrices, thereby enabling extended polymer-filler interfaces. As a result, the fiber-based composites exhibit enhanced dielectric performance over particle-filled composites. Multi-scale characterization reveals that the 1D fibrous structure promotes interfacial polarization and guides dipole alignment within the polymer matrix. Furthermore, the fiber-enhanced PENG was integrated into a wearable sensing platform for real-time monitoring and recognition of human motion with machine learning. This work demonstrates that one-dimensional inorganic salt fibers, as functional fillers, provide an effective strategy for enhancing interfacial polarization in flexible energy-harvesting systems.