Unveiling the mechanism of lignin nanofiller in boosting the performance of triboelectric nanogenerators

Lignin has been demonstrated as the tribopositive nanofillers in boosting the triboelectric performances of biopolymer-based triboelectric nanogenerators (TENGs). However, the complex structures of lignin caused the unclear understanding how the molecular structures of lignin affected the output performances of TENGs. Herein, for the first time, five fractionated lignin with different structures were innovatively employed as the tribopositive nanofillers in CMC. Computational simulations and experimental results verified that the lignin with more S units, A-type linkage and large molecular weight give rise to the higher dielectric constant as well as the triboelectric performances. Relying on this principle, the acetone lignin possessed the highest dielectric behavior and the constructed TENG delivered the maximum Voc of 204.34 V, Isc of 6.86 µA, Qsc of 70.27 nC and instantaneous output power density of 836.64 mW/m2 under contact frequency of 1 Hz. Moreover, such biofilm can be dissolved in water and the regenerated film delivered stable output performances at least 5 times. Our findings not only provided the in-depth understanding of the relationship between triboelectrification behaviors and molecular structures of lignin, but also boosted the rational designing high-performance lignin-based tribopositive nanofillers for self-powered sensing or mechanical energy harvesting.