Hardwood-derived lignin as a tribo-positive filler in electrospun PVDF nanofibers for efficient triboelectric energy harvesting

Abstract

It is essential to develop sustainable approaches for fabricating energy devices using natural materials like lignocellulosic biomass. Lignin, which is most abundant in nature, serves as a tribo-positive filler due to its chemical morphology. Herein, we isolated lignin from the raw hardwood via the soda pulping method and utilized the isolated lignin in developing composite nanofibers with polyvinylidene fluoride (PVDF), i.e., PVDF-lignin nanofibers (PLNFs), via an electrospinning technique. Triboelectric characteristics of PLNFs with different lignin concentrations were evaluated against polytetrafluorethylene (PTFE). An enhancement in performance was observed compared to raw PVDF. The electrical output of triboelectric nanogenerators (TENGs) made using PLNFs depends on their structural features, polarizability, dielectric properties, force, and frequency of vibration. Thus, the P10-L5 TENG (PVDF 10 wet% with 5% lignin) generates the highest output power density of approximately ∼60 mW m⁻². The high performance of the P10-L5 TENG is attributed to the uniform dimensions of nanofibers and high surface charge accumulation on the surface of PLNFs. Lignin-based TENGs exhibit excellent stability and endurance, enduring 10 000 cycles at 1 Hz, 3 Hz, and 5 Hz frequencies. The PLNFs produced a high-power output, while the indium tin oxide-coated PET sheets provide strength and flexibility, resulting in a stable, durable, and sustainable TENG system.