Highlights
Ti3C2Tx MXene-based coaxial zinc-ion hybrid fiber supercapacitors (FSCs) were fabricated with braided structure, which can be prepared continuously and present excellent flexibility and ultrastability.
A sports watch driven by the watch belts which weaved uses the obtained zinc-ion hybrid FSC and LED arrays lighted by the FSCs under embedding into textiles, demonstrating the great potential application in smart wearable textiles.
Abstract
Zinc-ion hybrid fiber supercapacitors (FSCs) are promising energy storages for wearable electronics owing to their high energy density, good flexibility, and weavability. However, it is still a critical challenge to optimize the structure of the designed FSC to improve energy density and realize the continuous fabrication of super-long FSCs. Herein, we propose a braided coaxial zinc-ion hybrid FSC with several meters of Ti3C2Tx MXene cathode as core electrodes, and shell zinc fiber anode was braided on the surface of the Ti3C2Tx MXene fibers across the solid electrolytes. According to the simulated results using ANSYS Maxwell software, the braided structures revealed a higher capacitance compared to the spring-like structures. The resulting FSCs exhibited a high areal capacitance of 214 mF cm–2, the energy density of 42.8 μWh cm−2 at 5 mV s−1, and excellent cycling stability with 83.58% capacity retention after 5000 cycles. The coaxial FSC was tied several kinds of knots, proving a shape-controllable fiber energy storage. Furthermore, the knitted FSC showed superior stability and weavability, which can be woven into watch belts or embedded into textiles to power smart watches and LED arrays for a few days.
In this study, the carbon fiber weft‐knitting (CFWK)‐reinforced composites were prepared and the deformation mechanism during acoustic emission (AE) and low‐velocity impact resistance. To fabricate CFWK composites, single‐sided 1 × 1 variable plain stitch, double‐sided interlock structure, and two inter‐ply and intra‐ply hybrid structures of the former two stitches were applied for reinforcements in epoxy films via hot‐pressing. Moreover, we evaluated the tensile and bending properties during AE and investigated the low‐velocity impact properties of CFWK‐reinforced composites to evaluate the failure mechanism of composites. Finally, we analyzed the effects of laminating numbers, ply angle, and fabric structure on the properties of CFWK‐reinforced composites. Results showed that the composites with 1 × 1 variable plain stitch reinforcement exhibited the highest tensile strength and bending strength (206.22 and 213.43 MPa, respectively) among the composites with a two‐layer structure. The tensile fracture strength of [0/90] laying was 35%–50% lower than that of [0/0] laying. In addition, the cluster analysis on AE signal frequency showed that fiber debonding was the main failure mode, accounting for 68% of the total debonding when stretching along the longitudinal direction of the two‐ply composite loop. Under the impact energy of 4 J, the maximum load of CFWK‐reinforced composites with three‐ply interlock increased by 275% compared to that of single‐ply composites. Furthermore, the three‐ply interlock CFWK‐reinforced composites were perforated under impact energy of 10 J.
In this study, low-velocity impact and interfacial bonding properties of weft-knitted ultra-high-molecular-weight-polyethylene (UHMWPE) filaments reinforced epoxy resin and vinyl ester resin composites were investigated. UHMWPE filament yarns of 600 D were applied to fabricate three weft-knitted structures of plain stitch, interlock air space stitch and swiss double pique. Vacuum-assisted resin infusion (VARI) technology was utilized to combine resin and fabric to form inter-ply hybrid rigid composites. The basic mechanics, impact resistance and puncture performance of the hybrid composites were evaluated and their interfacial bonding was analyzed. It was revealed that composites with interlock air space stitch reinforcement exhibited the highest mechanical properties and puncture resistance. Under the same weft-knitted reinforcement, the tensile and flexural properties of the epoxy matrix composites were better than vinyl ester matrix composites. However, their low-velocity impact resistance was a bit inferior. The interfacial bonding ability between vinyl ester resin and weft knitting structure reinforcement was stronger because of the similar material structure between resin and reinforcement. This process is important for determining the optimum bonding method to achieve extensive application and improve the shelf life of UHMWPE composites.
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