Enhancing triboelectric performance in PVDF-based folded spring-type triboelectric nanogenerators via heat-induced phase transition and dielectric optimization for energy harvesting and self-powered sensing†

As a promising and sustainable power source for smart electronic devices and self-powered devices, triboelectric nanogenerators (TENGs) have gained significant attention owing to their high energy conversion efficiency and versatile applications. In recent years, electrospun polyvinylidene fluoride (PVDF) nanofibers have emerged as an efficient material for enhancing TENG performance, owing to their high specific surface area, excellent mechanical properties and large-scale production. However, the insufficient output power of PVDF-based TENGs remains a critical challenge for practical applications. In this work, we construct folded spring-type triboelectric nanogenerators (FTENGs) based on heat treated optimized PVDF fibers, and comprehensively explore the impact of heat treatment on the phase transition and dielectric properties of PVDF, as well as the resultant enhancement in triboelectric performance. In-depth investigations reveal that the optimal heat treatment at 100 °C achieved the best balance between β-phase content (69.49%) and dielectric properties in PVDF. Furthermore, the important factors of the FTENG, including the number of layers, compression amplitude and external forces are also systematically elaborated. The optimized FTENG demonstrates outstanding performance with an open-circuit voltage of 100.94 V, a short-circuit current of 827.37 nA, and a peak power output of 470 μW at 45 MΩ load, demonstrating its capability to power a wide range of electronic devices. This study not only provides a practical strategy for enhancing the output performance of TENGs but also paves the way for their applications in energy harvesting and self-powered sensing systems, particularly in wearable electronics and IoT devices.