Lithium ion batteries (LIBs) have dominated the portable electric market over decades; however, the limited and unevenly distributed lithium resources induce concerns on their future large-scale applications. Increasing efforts have been endeavored on exploring post-Li ion batteries, such as Na-ion, K-ion, Al-ion and Mg-ion batteries, due to the high abundance of the corresponding elements in Earth crust. Manufacturing reliable electrode materials is the key to develop these new battery systems. Facile and scalable electrospinning has been widely utilized in preparing mechanically stable, flexible and conductive nanofiber electrodes as successfully proven in LIBs. In recent years, tremendous efforts have been devoted to electrospinning nanofiber electrodes for post-Li ion batteries and discernible progress in the electrochemical performance has been witnessed. Herein, we aim to review the-state-of-the-art advances made in electrospun nanofiber materials in optimizing post-Li ion battery technology by surveying the correlations among the morphology, the surface chemistry, the structure of electrospun nanofibers, and the post-Li ion batteries performance. Based on intensive investigations and insightful understandings, perspectives to the future design of electrospun nanofiber electrodes are also presented.
Wearable on-skin electrodes or conductors should be vapor permeable, strain-insensitive, isotropically stretchable and stable under cyclic stretching. Various strategies have been proposed to prepare the required conductors up to now; however, it is a challenge to fabricate them with above properties in a simple manner. In this paper, a highly permeable and stretchable conductor based on electrospun fluorine rubber fiber mat is reported. The fibers are pre-stretched in electric field during electrospinning, and they shrink isotropically by ~ 35–40% in area after being detached from the substrate. The obtained fiber mat conductor demonstrates high stretchability up to ~ 170%, and the resistance changes only 0.8 under 60% strain, which is superior to many other strain-insensitive conductors. The conductor possesses high stability, no cracks or structure damage are observed after washing and cyclic stretching. Moreover, the conductor is vapor permeable with a water vapor transmission rate of ~ 850 g m−2 day−1, which is comparable to the normal water evaporation in ambient conditions, indicating that it would not disturb the sweat evaporation when being used on skin. The conductor is successfully used as stretchable yarns and electromyography (EMG) electrodes, showing high reliability in E-textiles and on-skin applications.
Carbon nanotubes (CNTs) have generated remarkable interests in a wide range of research fields due to their excellent electrical properties. However, achieving the CNTs arrangement with high quality in a short time remains a challenge. Herein we studied the in-situ assembly of CNTs based on macroscopic dielectrophoresis by using a centimeter scale electrode, which overcome the limitation of small size in traditional method for manipulating nanoparticles. Ordered CNTs chains could be obtained under the action of alternating current dielectrophoresis by optimizing the voltage and frequency. Besides, the ordered chains were able to restore immediately upon powering up after being damaged. Furthermore, a CNTs chain was prepared for conducting the wet circuit and powering a LED, and different conductive patterns on the non-woven fabric were achieved by controlling the position of the electrodes in wet environment.
Immunosensor is a powerful tool in healthcare and clinic, food and drug industry, and environmental protection. Label-free fiber-optic immunosensors have shown a myriad of advantages, such as high sensitivity, anti-electromagnetic interference, and afield measurement via the fiber network. However, the fiber-optic based sensor may bear the temperature cross-talk, especially under the warming condition for bio-activating the immune molecules. In this study, we proposed a highly birefringent microfiber Bragg grating for immunosensing with the temperature-compensation. The birefringent microfiber was drawn from the elliptical cladding multimode fiber that was ablated by the CO2 laser. The considerably large energy overlap region offered by the original multimode fiber favored the efficient inscription of FBG with high reflectivity. The dual resonances derived by the orthogonal polarization states presented similar temperature responsivities but significantly different ambient refractive index sensitivities, allowing the temperature-compensational RI sensing. The human immunoglobulin G (IgG) molecules were anchored on the surface of the microfiber grating probe by the covalent functionalization technique to enable the specific detection of the anti-IgG molecule. The proposed method promises a high-efficiency and low-cost design for the microfiber Bragg grating-based biosensor without being subjected to the temperature cross-sensitivity.
The study aims to incorporate cellulosic canola (Brassica napus L.) biopolymers with wood biomass to increase flexural strength more than wood fraction alone. A facile fabrication process—at ambient temperature—is employed for ease of producing two different sets of bio-composites utilizing unsaturated polyester resin: pristine composite structures of 100% wood and hybrid composite structures of a canola-wood blend. The curing process is accompanied by methyl ethyl ketone peroxide (MEKP). Besides the lightweight feature, the hybrid composite structures exhibit maximum flexural strength up to 59.6 and 89.58 MPa at 2.5 and 5% fibre polymer fraction, outperforming the pristine wood composites (49.25 MPa). Also, the bending behaviours of the composite structures are illustrated by the load–deflection curves and the associated SEM micrographs display their fractured and debonded surface at the cross-section. The novel canola fibre benefits from its inherent hollow architecture, facilitating an excellent strength to weight ratio for the thermoset composites. Interestingly, canola displays a fibre diameter and density of 79.80 (± 41.31) μm and 1.34 (± 0.0014) g/cc, contributing effectively towards the flexure performance and high packing density. The breaking tenacity (13.31 ± 4.59 g-force/tex) and tensile strength (174.93 ± 60.29) of canola fibres are comparable to other bast fibres. The synergy among fibre diameters, density and breaking tenacity creates a good interphase to successfully transfer the external compressive load from the resin matrix to the fibres. Further, the two-parameter Weibull distribution model is applied for predicting the failure and reliability probability of composite specimens against a wide range of compressive loads. Finally, prioritized SWOT factors have been summarized associated with the prospects and key challenges of canola biopolymers—an attempt to strategize the planning and decision-making process for a potential business environment. The introduction of canola into the plastic industries would ultimately promote the application of sustainable biopolymers in diverse grounds including the interior panels for aerospace, automotive, and furniture industries.
A correction to this paper has been published: https://doi.org/10.1007/s42765-021-00074-y