Wet-spinning assembly and in situ electrodeposition of carbon nanotube-based composite fibers for high energy density wire-shaped asymmetric supercapacitor.

Wire-shaped supercapacitors (WSC) have attracted tremendous attention for powering portable electronic devices. However, previously reported WSC suffered from a complicated fabrication process and high cost. The objective of this study is to develop a facile and scalable process for the fabrication of high energy density WSC. We coupled the wet-spinning assembly with an in situ electrodeposition technique to prepare carbon nanotube (CNT)-based composite fibers. The charge balance between the electrodes was realized by controlling the deposition time of the pseudocapacitive materials. A wire-shaped asymmetric supercapacitor (WASC) was fabricated by twisting MnO2/CNT fiber cathode and PPy/CNT fiber anode with LiCl/PVA electrolyte. The flexible MnO2/CNT//PPy/CNT WASC operated in a broadened voltage range of 0-1.8 V exhibited a high capacitance of 17.5F cm-3 (10.7F g-1). In addition, it delivered a maximum energy and power densities of 7.88 mWh cm-3 (4.82 Wh kg-1) and 2.26 W cm-3 (1382 W kg-1), respectively. The WASC device demonstrated satisfactory cycling stability with 86% capacitance retention, and its Coulombic efficiency remained at 96% after 5000 charge-discharge cycles. The contributions of the diffusion-controlled insertion and the surface capacitive effect were theoretically quantified to investigate the energy storage mechanism. The fabrication approaches hold potential for the construction of cost-effective and high-performance WSC.

A Stretchable Yarn Embedded Triboelectric Nanogenerator as Electronic Skin for Biomechanical Energy Harvesting and Multifunctional Pressure Sensing.

Flexible and stretchable physical sensors capable of both energy harvesting and self-powered sensing are vital to the rapid advancements in wearable electronics. Even so, there exist few studies that can integrate energy harvesting and self-powered sensing into a single electronic skin. Here, a stretchable and washable skin-inspired triboelectric nanogenerator (SI-TENG) is developed for both biomechanical energy harvesting and versatile pressure sensing. A planar and designable conductive yarn network constructed from a three-ply-twisted silver-coated nylon yarn is embedded into flexible elastomer, endowing the SI-TENG with desired stretchability, good sensitivity, high detection precision, fast responsivity, and excellent mechanical stability. With a maximum average power density of 230 mW m-2 , the SI-TENG is able to light up 170 light-emitting diodes, charge various capacitors, and drive miniature electronic products. As a self-powered multifunctional sensor, the SI-TENG is adopted to monitor human physiological signals, such as arterial pulse and voice vibrations. Furthermore, an intelligent prosthetic hand, a self-powered pedometer/speedometer, a flexible digital keyboard, and a proof-of-concept pressure-sensor array with 8 × 8 sensing pixels are successively demonstrated to further confirm its versatile application prospects. Based on these merits, the developed SI-TENG has promising applications in wearable powering technology, physiological monitoring, intelligent prostheses, and human-machine interfaces.

A Highly Stretchable and Washable All-Yarn-Based Self-Charging Knitting Power Textile Composed of Fiber Triboelectric Nanogenerators and Supercapacitors.

Rapid advancements in stretchable and multifunctional wearable electronics impose a challenge on corresponding power devices that they should have comparable portability and stretchability. Here, we report a highly stretchable and washable all-yarn-based self-charging knitting power textile that enables both biomechanical energy harvesting and simultaneously energy storing by hybridizing triboelectrical nanogenerator (TENG) and supercapacitor (SC) into one fabric. With the weft-knitting technique, the power textile is qualified with high elasticity, flexibility, and stretchability, which can adapt to complex mechanical deformations. The knitting TENG fabric is able to generate electric energy with a maximum instantaneous peak power density of ∼85 mW·m-2 and light up at least 124 light-emitting diodes. The all-solid-state symmetrical yarn SC exhibits lightweight, good capacitance, high flexibility, and excellent mechanical and long-term stability, which is suitable for wearable energy storage devices. The assembled knitting power textile is capable of sustainably driving wearable electronics (for example, a calculator or temperature-humidity meter) with energy converted from human motions. Our work provides more opportunities for stretchable multifunctional power sources and potential applications in wearable electronics.

3D Orthogonal Woven Triboelectric Nanogenerator for Effective Biomechanical Energy Harvesting and as Self-Powered Active Motion Sensors.

The development of wearable and large-area energy-harvesting textiles has received intensive attention due to their promising applications in next-generation wearable functional electronics. However, the limited power outputs of conventional textiles have largely hindered their development. Here, in combination with the stainless steel/polyester fiber blended yarn, the polydimethylsiloxane-coated energy-harvesting yarn, and nonconductive binding yarn, a high-power-output textile triboelectric nanogenerator (TENG) with 3D orthogonal woven structure is developed for effective biomechanical energy harvesting and active motion signal tracking. Based on the advanced 3D structural design, the maximum peak power density of 3D textile can reach 263.36 mW m-2 under the tapping frequency of 3 Hz, which is several times more than that of conventional 2D textile TENGs. Besides, its collected power is capable of lighting up a warning indicator, sustainably charging a commercial capacitor, and powering a smart watch. The 3D textile TENG can also be used as a self-powered active motion sensor to constantly monitor the movement signals of human body. Furthermore, a smart dancing blanket is designed to simultaneously convert biomechanical energy and perceive body movement. This work provides a new direction for multifunctional self-powered textiles with potential applications in wearable electronics, home security, and personalized healthcare.