Knittable Composite Fiber Allows Constant and Tremendous Self‐Powering Based on the Transpiration‐Driven Electrokinetic Effect

Abstract

The electrokinetic effect allows harvesting renewable energy directly from moisture, sweat, and rainwater, which is one of the promising techniques for self-powered electronics. However, current fibrous hygroelectric nanogenerators still suffer from either an intermittent energy harvesting mode or a limited electricity supply. Herein, learning from the transpiration process in plants, a conductive and hydrophilic cellulose/carbon nanotubes fiber is reported, in which continuous and efficient water flow can be driven by the macromolecular chain channel and spontaneous evaporation. In combination with the electrokinetic mechanism, just a single self-powered fiber is found to produce a constant and tremendous open-circuit voltage of 160.4 mV and a considerable power density up to 0.4 mW cm −3 . This record-high output performance with the feature of continuity and durability is about one order of magnitude higher than that of most conventional fibrous hygroelectric nanogenerators. Eventually, 108 fibers in series or parallel are woven into flexible fabrics, yielding the maximum power supply of 1.2 V with only 10 min charging time, capable of powering an electronic calculator. This work fabricates a knittable and designable self-powering fiber with excellent aesthetics and comfort for practical application, offering a novel concept and an effective approach toward clean energy usage.

Highly Sensitive Self-Powered Humidity Sensor Based on a TaS2/Cu2S Heterostructure Driven by a Triboelectric Nanogenerator

“…These results demonstrate the potential of TaS 2 /Cu 2 S heterostructure humidity sensors for monitoring noncontact humancomputer interaction. 44,45…”

Engineering Polymeric Nanofluidic Membranes for Efficient Ionic Transport: Biomimetic Design, Material Construction, and Advanced Functionalities

“…235 For example, continuous electricity can be outputted by an ion-conductive cellulose/carbon nanotubes (CNTs) fiber, in which an efficient electrolyte flow can be driven by spontaneous evaporation within its hydrophilic cellulose channels. 246 Owing to the function of the electrokinetic effect, a single fiber can produce a constant open-circuit voltage of 160.4 mV and a power density up to 0.4 mW cm −3 , and 108 fibers in series or parallel can yield the maximum power supply of 1.2 V. In another example, a nanofluidic membrane composed of a conductive MOF layered on CNFs has been developed to enable efficient solar power generation based on ionic thermophoresis and electrokinetic effects. 247 Given the strong photothermal effect and low thermal conductivity of such membrane, a large thermal gradient can be produced on membrane surface under light illumination to induce fast water evaporation and drive selective ion transport within charged nanochannels, thus generating ionic thermoelectric and streaming potentials, respectively.…”

“…Besides mechanical stimulus, the electrokinetic effect within charged nanochannels can be also induced by other external stimuli, such as evaporation and transpiration . For example, continuous electricity can be outputted by an ion-conductive cellulose/carbon nanotubes (CNTs) fiber, in which an efficient electrolyte flow can be driven by spontaneous evaporation within its hydrophilic cellulose channels . Owing to the function of the electrokinetic effect, a single fiber can produce a constant open-circuit voltage of 160.4 mV and a power density up to 0.4 mW cm –3 , and 108 fibers in series or parallel can yield the maximum power supply of 1.2 V. In another example, a nanofluidic membrane composed of a conductive MOF layered on CNFs has been developed to enable efficient solar power generation based on ionic thermophoresis and electrokinetic effects .…”

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

“…To date, it is still a challenge to develop a fiber based moist-electric generator (FMEG) with high output, especially when a large scale of preparation and cost-effective assembly are required. 19…”

“…To date, it is still a challenge to develop a ber based moist-electric generator (FMEG) with high output, especially when a large scale of preparation and cost-effective assembly are required. 19 The mechanisms of moist-electric generation are generally categorized into "ow currents" and "ion gradient diffusion". 9 In the case of polymers, "ionic gradient diffusion" is the main mechanism for power generation and more dependent on the number of oxygenated functional groups in active materials.…”