Ultra-enhanced energy harvesting and storage in PVDF composites via flake-to-rod transformed Ag-doped ZnO nanorods for smart wearables and embedded security devices

초록

Harvesting energy from human motion using piezoelectric and triboelectric materials has emerged as a promising approach to sustainably power smart wearables. However, progress remains limited due to the challenges in developing cost-effective, flexible, durable, and highly responsive materials. This study introduces a high-performance filler (f-Zn1-xAgxO, functionalized Ag-doped ZnO) and robust PVDF/f-Zn1-xAgxO composites with remarkable energy storage capacity. The filler was carefully engineered by doping ZnO with 2 wt% Ag, followed by APTES functionalization (f-Zn0.98Ag0.02O), transforming its structure from nanoflakes to uniaxial nanorods, significantly enhancing interfacial interactions and energy storage capacity. When an optimized 30 vol% of f-Zn0.98Ag0.02O is mixed with PVDF matrix, the resulting composite achieves an energy storage density (W-rec) of similar to 11.6 J/cm(3), 39 times higher than PVDF (0.3 J/cm(3)), with 85 % efficiency(eta) and reduced dielectric loss. Additionally, the PVDF/f-Zn0.98Ag0.02O composite exhibited an outstanding piezoelectric power density of 42.5 mu W/cm(2), similar to 56.7 times higher than neat PVDF (0.75 mu W/cm(2)), surpassing many contemporary reports that utilized even more complex materials and processes. A small piezoelectric nanogenerator (PENG) based on this composite successfully powered 26 colorful LEDs and responded effectively to various biomechanical movements and toy motions, demonstrating its versatility and potential across various applications. Moreover, the PENG exhibits significant potential for security systems, as it can differentiate unique signal patterns under various conditions when integrated into ATMs and smart door systems. These findings highlight the versatility and promise of our composites for next-generation energy harvesting and storage, security applications, and smart wearables.

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