Preparation And Performance Of Cellulose Nanofibril Composites Based Triboelectric Nanogenerator

As an emerging branch of energy conversion technology,the triboelectric nanogenerator（TENG）has exploited a new path for the renewable energy.The triboelectric materials are the important part of TENG,which affect the performance and development of TENG.The triboelectric materials currently used mainly include metals（i.e.,silver and copper）,metal oxides（i.e.,zinc oxide and indium tin oxide）and non-renewable synthetic polymers（i.e.,polyamide,polyfluorinated,ethylene propylene,polydimethylsiloxane）.Cellulose nanofibrils（CNFs）are natural polymer materials extracted from plants,with high specific surface area and biocompatibility,and have great potential in the construction of TENG materials.CNF composites are fabricated using vacuum-assisted filtration with CNFs and multiwalled carbon nanotube（MWCNT）.When the MWCNT loading is 30wt.%,the rheological properties of CNF suspension change significantly,and the obtained CNF composites have different conductivity in the cross-plane(～2.13×10^-2 S/cm)and the in-plane(～5.30×10^-5 S/cm).Interestingly,TENG with CNF composites（30 wt.%）has better output performance,and its transfer charge is increased by 45%compared with CNF film.In order to expand the application of CNF composite film in TENG triboelectric materials,a multilayer CNF composite based TENG was prepared by constructing an Ag layer as the charge transport layer and electrospinning the polyacrylonitrile-PbTiO₃（PAN-PbTiO₃）layer as the charge storage layer on the surface of the friction layer,respectively.The charge of the MC-TENG increased by 90%compared with CNF film.A theoretical model was established to clarify the mechanism of output performance enhancement.This new strategy can be used with sustainable and degradable cellulosic materials,compensating for their lack of electrical conductivity and expands their application in the field of friction materials.In order to solve the problem of the weak electron-obtaining ability of cellulose in triboelectric materials,CNFs are good dispersant and combined with MXene and PVDF to prepare the electrospinning CNF/MXene/PVDF film.It has a porous structure,and the addition of CNF/MXene changes the properties of the PVDF solution,causing evaporation-induced phase separation.The performance of CNF/MXene/PVDF nanofibers based TENG is affected by the content of MXene and the spinning time.When the content of MXene is 4 wt.%and the spinning time is 120 min,the short-circuit current of TENG is 9.5μA.This work helps to expand the application of fiber materials in TENG materials.