Sodium alginate based skin-core fibers with profoundly enhanced moisture-electric generation performance and their multifunctionality

Abstract

Moist-electric generation as a sustainable energy acquisition technology exhibits great potential to solve energy and environmental problems. However, the simultaneous achievement of flexibility, continuous electric generation and high output performance of moist-electric fibers remains a great challenge. In this work, a coaxial fiber based moist-electric generator (FMEG) was prepared by means of a facile and continuous coaxial wet spinning technology. The skin-core structure, in which sodium alginate (SA)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) formed a moisture absorbing and oxygenated group containing a skin and multi-walled carbon nanotube (MWCNT) core, endowed this FMEG with the strong capability of electric charge motion in radial and axial directions of the fiber, which was assisted by the enhanced moisture migration from the skin to the core layer. Meanwhile, the MWCNT core and an external metal wire formed a pair of asymmetric electrodes when SA/PEDOT-MWCNT coaxial fibers were assembled to be a MEG device. This provided a significant built-in electric field which contributed to additional impetus for proton migration. Consecutive and stable output power with an extremely high level of output power density of 5.56 W m⁻² (RH = 61–64%), output voltage of 1.2 V, and output current of 21.0 μA was generated by a piece of coaxial fiber of only 1 cm in length, which is highly superior to those in most reported studies. At the same time, the SA/PEDOT:PSS-MWCNT skin-core fiber exhibited multifunctionality in thermoelectric and Joule heating properties. The excellent green power generation ability of the coaxial fiber is undoubtedly highly competitive in the field of wearable and sustainable power generation textiles and devices.