Design of High-Performance Wearable Energy and Sensor Electronics from Fiber Materials.

A fiber material is composed of a group of flexible fibers that are assembled in a certain dimensionality. With its good flexibility, high porosity, and large surface area, it demonstrates a great potential in the development of flexible and wearable electronics. In this work, a kind of nickel/active material-coated flexible fiber (NMF) electrodes, such as Ni/MnO2/reduced graphene oxide (rGO) NMF electrodes, Ni/carbon nanotube (CNT) NMF electrodes, and Ni/G NMF electrodes, is developed by a new general method. In contrast with previous approaches, it is for the first time that porous and rich hydrophilic structures of fiber materials have been used as the substrate to fully absorb active materials from their suspension or slurry and then to deposit a Ni layer on active material-coated fiber materials. The proposed processes of active material dip-coating and then Ni electroless plating not only greatly enhance the electrical conductivity and functional performance of fiber materials but also can be applied to an extensive diversity of fiber materials, such as fabrics, yarns, papers, and so on, with outstanding flexibility, lightweight, high stability, and conductivity for making kinds of energy and sensor devices. As demonstration, a two-dimensional (2D) Ni/MnO2/rGO NMF electrode is obtained for supercapacitors, showing excellent electrochemical performance for energy storage. Then, Ni/CNT NMF electrodes with different dimensionalities, including one-dimensional fiber-shaped, 2D plane, and three-dimensional spatial, are fabricated as various tensile and compressive strain sensors for observation of human's movements and health. Finally, a 2D Ni/graphene NMF electrode is developed for assembling triboelectric nanogenerators for mechanical energy harvesting. Benefiting from wearable property of the textile substrates, the obtained NMF electrodes are expected to be designed into kinds of wearable devices for the future practical applications. The NMF electrode designed in this work provides a simple, stable, and effective approach for designing and fabricating wearable energy and sensor electronics from fiber materials.