The research and applications of fiber materials are directly related to the daily life of social populace and the development of relevant revolutionary manufacturing industry. However, the conventional fibers and fiber products can no longer meet the requirements of automation and intellectualization in modern society, as well as people’s consumption needs in pursuit of smart, avant-grade, fashion and distinctiveness. The advanced fiber-shaped electronics with most desired designability and integration features have been explored and developed intensively during the last few years. The advanced fiber-based products such as wearable electronics and smart clothing can be employed as the second skin to enhance information exchange between humans and the external environment. In this review, the significant progress on flexible fiber-shaped multifunctional devices, including fiber-based energy harvesting devices, energy storage devices, chromatic devices, and actuators are discussed. Particularly, the fabrication procedures and application characteristics of multifunctional fiber devices such as fiber-shaped solar cells, lithium-ion batteries, actuators and electrochromic fibers are introduced in detail. Finally, we provide our perspectives on the challenges and future development of functional fiber-shaped devices.
Electrospun nanofibers hold a great potential in biomedical applications due to their advantages of large specific surface area, good biocompatibility, easy fabrication and surface modification. In particular, organic/inorganic hybrid nanofibers exhibit enhanced mechanical properties and long-term sustained release or controlled release profile of encapsulated drugs, which enables hybrid nanofibers to serve as desired platform for drug delivery and tissue engineering applications. This review summarizes the recent progresses in the preparation, performances and applications of hybrid nanofibers as drug delivery vectors for antibacterial and antitumor therapy, and as nanofibrous scaffolds for bone tissue engineering or other types of tissue engineering applications. Nanofibers doped with various types of inorganic nanoparticles (e.g., halloysite, laponite®, nano-hydroxyapatite, attapulgite, carbon nanotubes, and graphene, etc.) are introduced and summarized in detail. Future perspectives are also briefly discussed.
Solid electrolytes have gained attention recently for the development of next-generation Li-ion batteries since they can fundamentally improve the battery stability and safety. Among various types of solid electrolytes, composite solid electrolytes (CSEs) exhibit both high ionic conductivity and excellent interfacial contact with the electrodes. Incorporating active nanofibers into the polymer matrix demonstrates an effective method to fabricate CSEs. However, current CSEs based on traditional poly(ethylene oxide) (PEO) polymer suffer from the poor ionic conductivity of PEO and agglomeration effect of inorganic fillers at high concentrations, which limit further improvements in Li+ conductivity and electrochemical stability. Herein, we synthesize a novel PEO based cross-linked polymer (CLP) as the polymer matrix with naturally amorphous structure and high room-temperature ionic conductivity of 2.40 × 10−4 S cm−1. Li0.3La0.557TiO3 (LLTO) nanofibers are incorporated into the CLP matrix to form composite solid electrolytes, achieving enhanced ionic conductivity without showing filler agglomeration. The high content of Li-conductive nanofibers improves the mechanical strength, ensures the conductive network, and increases the total Li+ conductivity to 3.31 × 10−4 S cm−1. The all-solid-state Li|LiFePO4 batteries with LLTO nanofiber-incorporated CSEs are able to deliver attractive specific capacity of 147 mAh g−1 at room temperature, and no evident dendrite is found at the anode/electrolyte interface after 100 cycles.
A highly ionic-conductive 3-D fiber network composite solid electrolyte is introduced based on Li-ion conducting nanofibers and amorphous poly(ethylene oxide) (PEO) cross-linked polymer. With the reinforcement of Li0.3La0.557TiO3 (LLTO) nanofibers, the continuous 3D conduction network formed within the polymer matrix greatly enhances the electrochemical and mechanical properties of resultant composite solid electrolytes. Consequently, the lithium dendrite is effectively controlled after long cycles, and the all-solid-state Li|LiFePO4 prototype cells demonstrate excellent cycling stability at room temperature.
Thermal management of textiles requires local microclimate control over heat and wet dissipation to create a comfortable thermal-wet environment at the interface of the human body and clothing. Herein, we design a fabric capable of both sweat- and cooling-management using a knitted fabric featuring a bilayer structure consisting of hydrophobic polyethylene terephthalate and hydrophilic cellulose fibers to simultaneously achieve high infrared (IR) transmittance and good thermal-wet comfort. The IR transmission of this cooling textile increased by ~ twofold in the dry state and ~ eightfold in the wet state compared to conventional cotton fabric. When the porosity changes from 10 to 47% with the comparison of conventional cotton fabric and our cooling textile, the heat flux is increased from 74.4 to 152.3 W/cm2. The cooling effect of the cooling fabric is 105% greater than that of commercial cotton fabric, which displays a better thermal management capacity for personal cooling. This bilayer design controls fast moisture transfer from inside out and provides thermal management, demonstrating high impact not only for garments, but also for other systems requiring heat regulation, such as buildings, which could mitigate energy demand and ultimately contribute to the relief of global energy and climate issues.
Elastic, repairable and conductive fibers are desirable in the newly emerging field of soft electronic and wearable devices. Here, we design a multifunctional fiber by incorporation of different components to optimize its performance. The combination of the poly(acrylic acid) (PAA) and poly(ethylene oxide) (PEO) through hydrogen bonding endows the fiber with high elasticity and repairability. Polydopamine (PDA) significantly increases the stability of the fiber, thus the fiber will not dissolve in alkaline solutions and still keep the repairable ability. The fiber shows a reversible swelling-shrinking property as pH values go up and down. Further, the conductive component, carbon nanotube, is adsorbed at the swelling state and then is fastened with fiber shrinking.