Biomass-Based Composite Nanofibers with Excellent Conductivity and Flexibility for Energy Storage and Sensing

The incompatibility of flexibility and conductivity for biomass-based carbon materials severely limits their application in flexible capacity storage devices, electronic skin, and signal sensor. In this work, a composite strategy of one-dimensional metal nanowires and chemically modified lignin is designed for the preparation of biomass-based nanofibers with outstanding electrical conductivity and flexibility. The introduction of silver nanowires with high electrical conductivity, high aspect ratio, and intrinsic flexibility can effectively improve the electrical conductivity of the obtained biomass-based composite nanofibers. The phosphorylated lignin is executed as the cross-linking point between silver nanowires and biomass-based nanofibers, which can increase the interweaving degree of the composite and thereby improve the effect of silver nanowires as the flexible external force absorbing material. The obtained biomass-based composite nanofibers exhibit excellent electrical conductivity (3.2 × 10² S/m), good specific capacitance (395 F/g), and high energy density (54.86 Wh/kg), and their fracture stress and elongation at break are increased by a factor of 78 and 11, respectively, compared to the biomass-based composite nanofibers without AgNWs. In particular, the biomass-based composite nanofibers possess outstanding biocompatibility and flame retardancy and can be utilized for human motion monitoring and heat-sensitive fire alarms with a response time of 0.5 s and a relative resistance change of essentially 100%. This composite strategy presented in this work is highly informative for the design and preparation of high-performance biomass-based carbon materials with excellent electrical conductivity and flexibility.