Carbon Yarns Research Articles

A multiscale homogenization iterative algorithm of 2D orthogonal prepreg carbon/aramid/epoxy woven-ply

An orthogonal mixture woven composites with aramid yarns and carbon yarns are investigated in this work. A dual-scale computational homogenization algorithm is also proposed to address the cross-scale numerical problems. Models and methods for mesoscale and macroscale are illustrated separately. Two types of meso-structures are selected for comparison, which are termed as representative unit cell (RUC) and equivalent cross-ply laminate (ECPL), and the corresponding macro-structures are referred to as RUCs and equivalent cross-ply laminate plain-woven composites (ECPL-PWC). The key finds clarified that the ECPL-PWC takes more computational expenses compared with the RUCs, but the RUCs is in acceptable agreement with testing results, as well as the evaluation results of the ECPL-PWC would obtain very satisfactory accuracy through minor numerical adjustments. The final finite element damage results reveals that the RUCs is more accurate for local damage assessment, while the ECPL-PWC is better for global damage analysis.

A facile blow spinning technique for green cellulose acetate/polystyrene composite separator for flexible energy storage devices

The search of sustainable gadgets, such as the portable electronics and wearables, have sparked the need for more sustainable and environment friendly constituent elements (e.g., electrode materials, separators, and green electrolytes) and low-cost scalable fabrication techniques. Herein, a facile and scalable blow spinning technique is proposed for the synthesis of a cellulose-based separator for flexible energy storage devices. A cellulose acetate and polystyrene (CA:PS) based composite separator is synthesized for the first time for flexible supercapacitors by exploiting the blow spinning technique. Different combinations of CA:PS were synthesized, and electrochemical performances of the devices were evaluated. A sweat simulation solution is used as green electrolyte for the development of symmetrical carbon yarn-based supercapacitors. The influence on the device performances of pristine carbon yarn, activated carbon yarns and PEDOT functionalized carbon yarns, electrodes were compared. Specific capacitances of 2.8 Fg−1 and 33 Fg−1 were obtained for pristine carbon and PEDOT functionalized carbon fibers respectively. The fabricated devices exploiting the composite separator exhibited good washing stability up to 30 cycles and capacitance retention of 95% up to 1000 charge/discharge cycles.

Bioelectricity production and bioremediation from sugarcane industry wastewater using microbial fuel cells with activated carbon cathodes

Clean energy and water are major challenges to meet for sustainable development. Microbial Fuel Cells or MFCs can treat wastewater with the treatment process becoming a method for capturing energy in the form of bioelectricity. In this work, biomass derived Activated Carbon was used as the MFC cathode with carbon yarn as the brush anode. Sugarcane processing plant wastewater was used to evaluate bioelectricity generation and contamination removal over multiple cycles. System performance was stable, this is attributed to absence of carboxylic acid functional group on cathode surface and the sufficiently developed bacteria biofilm on the anode. The reactors used were able to facilitate organic matter degradation continually. MFC reactors developed open circuit voltage of 870 ± 20 mV, and power density of 563 ± 30 mW/m2 with external resistors, having current density of 0.79 mA/m2. The chemical contamination of the wastewater was reduced from 1201 ± 60 mg/l to 240 ± 31 mg/l with average removal of 81%, with BOD removal efficiency of 86%. The utility of biomass derived Activated Carbon as a cathode material was evaluated with BET analysis, having a surface area of 230.131 m2/g for oxygen reduction. Surface feature includes distinct mesoporous structures for the growth of heterotrophs. Additionally, FTIR analysis of cathodes revealed the presence of heteroatoms on the carbon matrix which adds stability to its surface chemistry. This makes the cathode surface suitable for operation in real time conditions without corroding metal mesh collectors on which they are coated.

Studies on the mechanical and durability performance of textile reinforced geopolymer concrete beams

The steel reinforcements used in structural elements are prone to corrosion due to adverse environmental effects. Hence, in recent years, the development of sustainable materials to replace steel reinforcement in concrete has been under research. In this paper, the mechanical and durability characteristics of Geopolymer Concrete (GC) and Epoxy-coated Carbon (EC) yarn against chemical attack were investigated. Tension tests were conducted on EC yarns immersed in acid, sulfate, marine water, and alkaline solution over an exposure period of 1 year. The test results reveal that better durability was achieved for GC specimens compared to cement concrete (CC) specimens in terms of water absorption, acid resistance, sulfate resistance, marine water attack, and chloride diffusion. Compressive strength and flexural strength obtained were 2.6–7.7 times and 1.65–2.36 times higher in GC compared to CC after immersion in various chemical solutions for 6 months. The chemical resistance of EC yarns over an exposure period of 1 year was measured with respect to loss in tensile strength and the reduction in strength was obtained as 29.6% for EC yarns immersed in acid solution, 14.71% in sulfate solution, 7.06% in alkali, and 3.82% in marine water. The study also investigated the flexural behavior of Textile Reinforced Geopolymer Concrete (TRGC) beams (100 × 100 × 500 mm) subjected to monotonic loading. The effectiveness of textile yarn spacing and the number of carbon textile layers to improve the load-bearing behavior of GC beams were evaluated. The reinforcing benefits of TRGC can be confirmed from the load-deflection graph in terms of ultimate load-carrying capacity, post-peak behavior, and failure mode. An energy absorption capacity of 80.06% was found for TRGC-4 L beams compared to TRGC-1 L beam specimens (43.76%), i.e., TRGC specimens with 4 layers showed improved strength and ductility compared to one layer of carbon textile. The failure surface of the TRGC sample was examined using Scanning Electron Microscope (SEM), and fiber-matrix interaction was identified. Hence, despite the high cost of carbon yarn, TRGC can be used for special applications where corrosion protection and durability are controlling parameters.

Scalable, high-performance, yarn-shaped batteries activated by an ultralow volume of sweat for self-powered sensing textiles

One-dimensional sweat-activated batteries (SABs) provide a practical solution to generating electricity for textile electronics due to their excellent flexibility, biocompatibility, and compatibility with conventional textile techniques. However, the low power outputs and slow, inefficient activation during the initial perspiration stage greatly hamper their applications in textile-based, self-powered sensing systems. To address this issue, we developed a core-sheath-structured sweat-activated yarn battery (SAYB) with a Zn-wire core, a cotton-yarn sheath, and an outermost carbon yarn that served as the anode, sweat-wicking separator, and cathode, respectively. The battery has a power density of 1.72 mW cm−2 and an energy capacity of 15.3 mAh, which are much greater than those of the previously reported cotton-yarn-based SAB. The SAYB could be activated by only 1 μL of 100 mM NaCl solution within 3 s, thanks to the thin, hydrophilic cotton sheath, which may shorten the distance and accelerate liquid penetration between the electrodes. The batteries could tolerate 10,000 cycles of bending, 2800 cycles of twisting, and 20 cycles of washing without significantly reducing their power outputs. Multiple batteries connected in proper configurations could power headlights or charge portable gadgets like a smart watch and a smart phone. The SAYB was produced on a large scale (60 m long) to create a sweat-activated energy fabric (5 m long and 0.5 m wide) using conventional weaving techniques. The fabric was further combined with mini wireless analyzers and strain-sensing yarns to prepare a self-powered sensing T-shirt. The T-shirt can be triggered to wirelessly monitor the arm swing frequency and breathing rate in real time after wicking up the sweat created by a volunteer while he is jogging. The SAYBs are expected to contribute to the production of self-powered smart garments for wearable healthcare and exercise monitoring as reliable one-dimensional power sources.

All-Carbon Solution-Gated Transistor with Low Operating Voltages for Highly Selective and Stable Dopamine Sensing.

The diversity of carbon materials makes it possible to prepare all-carbon electronic devices requiring components with different properties and functions. In this work, we fabricate an all-carbon solution-gated transistor (AC-SGT) based dopamine (DA) sensor with Nafion coated nitrogen and oxygen co-doped carbon yarn (Nafion/NOCY) as the gate electrode and graphene as the channel. The carbon materials in AC-SGT render the usage of a variety of strategies to improve its electrochemical sensing capability including the modification of the gate electrode and the modulation of the operating voltage. With a low gate-source voltage of 0.02 V as well as a low drain-source voltage of 0.05 V, AC-SGT manifests the outstanding DA sensing performances in terms of sensitivity, selectivity, limit of detection (3 nM, S/N > 3), linear range (3 nM to 300 μM), long-term stability (over 30 days), and preconditioning time (60 s). Furthermore, a smartphone controlled portable sensing system integrated with AC-SGT is fabricated herein, which shows the excellent in vitro sensing capability of DA in urine, proving the potential of all-carbon transistors in smart wearable biosensors.

Investigation of the use of textile carbon yarns as sustainable shear reinforcement in concrete beams

In recent years, textile reinforcement has been widely researched and used in reinforced concrete beams, slabs, and thin plates. However, the design for bending is completely different from that of the shear case. The use of textile carbon yarns in place of or in addition to traditional steel stirrups to reinforce the shear has been investigated. Eight beams with dimensions of 200 mm × 300 mm × 1500 mm were used in this investigation. These beams were tested in shear under four load points. Two specimens were used with and without steel stirrups as reference specimens, while the other six beams used textile carbon yarns instead of steel stirrups. The variables of this study were the length of overlap, which was 30%, 60%, and 100%, the spacing was 90 mm and 130 mm, while inclination was 45° and 90°, and bonding with or without steel fibers. The results showed that using 100% overlap length, 90 mm spacing, a 45° angle, and adding steel fibers increased the shear capacity, increased the deflection, and made the cracking behavior better.

A Smart Textile Band Achieves High-Quality Electrocardiograms in Unrestrained Horses.

Electrocardiography (ECG) is an essential tool in assessing equine health and fitness. However, standard ECG devices are expensive and rely on the use of adhesive electrodes, which may become detached and are associated with reduced ECG quality over time. Smart textile electrodes composed of stainless-steel fibers have previously been shown to be a suitable alternative in horses at rest and during exercise. The objective of this study was to compare ECG quality using a smart textile girth band knit with silver and carbon yarns to standard adhesive silver/silver chloride (Ag/AgCl) electrodes. Simultaneous three-lead ECGs were recorded using a smart textile band and Ag/AgCl electrodes in 22 healthy, mixed-breed horses that were unrestrained in stalls. ECGs were compared using the following quality metrics: Kurtosis (k) value, Kurtosis signal quality index (kSQI), percentage of motion artifacts (%MA), peak signal amplitude, and heart rate (HR). Two-way ANOVA with Tukey's multiple comparison tests was conducted to compare each metric. No significant differences were found in any of the assessed metrics between the smart textile band and Ag/AgCl electrodes, with the exception of peak amplitude. Kurtosis and kSQI values were excellent for both methods (textile mean k = 21.8 ± 6.1, median kSQI = 0.98 [0.92-1.0]; Ag/AgCl k = 21.2 ± 7.6, kSQI = 0.99 [0.97-1.0]) with <0.5% (<1 min) of the recording being corrupted by MAs for both. This study demonstrates that smart textiles are a practical and reliable alternative to the standard electrodes typically used in ECG monitoring of horses.

Fabrication of Binder-Free and High Energy Density Yarn Supercapacitor for Wearable Electronics

Textile-based electronics systems are gaining considerable popularity nowadays and the area of wearable electronics technology is going to explode in the near future. Currently, the research on the flexible and wearable energy storage devices, to realize as power sources in wearable electronics, is on the boom. Herein, a flexible yarn-based supercapacitor (YSC) is fabricated utilizing TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanofibers and multiwalled carbon nanotube deposited on carbon yarn through the facile electrophoretic deposition technique for flexible/wearable energy storage application. The binder-free, mechanically strong, and compact deposition of the active materials on carbon yarn promotes the charge/ionic transport. The fabricated YSC device delivers a capacitance of 36.8 mF/cm at 0.1 mA/cm current rate. Moreover, the device shows 90% capacitance retention after 10 000 cycles proving excellent mechanical stability for energy storage. Furthermore, the YSC shows 95% retention after 2000 bending cycles at 0.5 mA/cm, suggesting good flexibility of the device. The YSC device shows a maximum energy density of 11.5 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> Wh/cm and power density of 368 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> W/cm, which is better than many YSCs reported in the literature. Three YSCs are integrated into a wearable fabric and glow a red LED for more than 5 min as demonstrated in the video proving its practical application.

Analysis of Dispersibility Effect of Carbon Additives on Ignitability of Ammonium-Dinitramide-Based Ionic Liquid Propellants Using Continuous Wave Laser Heating

ABSTRACT Ammonium dinitramide-based ionic liquids (ADN-EILPs) are a promising alternative to hydrazine monopropellants. Continuous wave (CW) laser heating using carbon wools is an effective approach to attain the rapid ignition of ADN-EILPs. This study aims to verify the influence of the dispersibility of carbon additives in ADN-EILPs on their ignition. The investigation was performed by performing fluorescence microscopy of samples imitating the mixture of ADN-EILPs with carbon additives and CW laser ignition tests of ADN-EILPs with several yarn-lengths of carbon wools. Based on these results, the dispersity mechanism of carbon additives in ADN-EILPs is proposed, which indicates that the use of high-power laser is not an effective approach to ignite ADN-EILPs consisting of carbon additives with high dispersibility. During sample preparation for the ignition tests, it was verified that the difference in the length of carbon yarns affects the bulk density and morphology of the prepared samples, and dispersibility of carbons. The results of the ignition tests indicate that samples whose morphology altered into a liquid-like morphology cannot be ignited and the ones who retained their original one can be ignited. The physical distribution of the residue of samples with a liquid-like morphology, observed after the ignition tests, agrees with the discussion regarding the dispersibility mechanism of carbon additives, obtained through fluorescence microscopy. Moreover, for the samples exhibiting an ignition capacity, the bulk density of additives would be crucial to be considered to achieve the effective ignition.

Preparation and characterization of a novel carbon/PAN/PPy@Zn yarn electrode

To fulfill the growing demand for durable and deformable flexible wearables, this study proposes a fibrous zinc ion battery negative electrode that is low-cost, easy to prepare, and similar to the flexible yarn. We have constructed a new type of carbon fiber/polyacrylonitrile(PAN)/polypyrrole(PPy) Zn electrode (CPP@Zn yarn electrode). Based on carbon fiber yarn, PAN wrapped carbon yarn (CP yarn) was prepared by electrospinning. PPy nanoparticles were deposited on CP yarn by in-situ polymerization to get the highly conductive yarn (CPP yarn). Finally, Zn is deposited on the CPP yarn by electrodeposition to obtain the CPP@Zn yarn electrode. When the deposition voltage is 1 V and the time is 30 min, the flexibility and the Zn crystal morphology of the CPP@Zn yarn electrode are the best, the specific capacity is the highest. When the current density is 0.04 A·cm−1, the specific capacity can reach 981.3 mF·cm−1 and the energy density is 0.18 W·h·cm−1. After cyclic charge and discharge repeated 300 times, 87.76% of the original specific capacity can still be maintained. After bending the CPP@Zn yarn electrode for 500 times, the specific capacitance can still maintain 86.13% of the original specific capacitance. The yarn electrode has excellent electrochemical stability and flexibility, and it has broad application prospects in wearable smart textiles.

Bond behavior of polymer- and mineral-impregnated carbon fiber yarns towards concrete matrices at elevated temperature levels

The bond of textile reinforcements towards concrete matrices plays an important role in the mechanical performance of Textile Reinforced Concretes, and the textile impregnation material is a crucial factor. In this work, the bond between different carbon yarns towards a concrete matrix was evaluated at elevated temperatures. A lab-developed cement-based (C) and geopolymer (GP) Mineral-impregnated Carbon Fibers (MCF) and commercially available epoxy resin (EP) coated carbon yarns were assessed. Both MCF yarns yielded high tensile strength and modulus of elasticity, compatible with commercial EP yarns. The C-MCF yarn showed higher bond strength towards the matrix than the GP-MCF yarn, probably due to better chemical compatibility. The EP yarn yielded the strongest bond towards the matrix at room temperature. At elevated temperatures, the bond between the EP yarn and concrete matrix became considerably weaker, while the MCF yarns could maintain a sufficient bond up to 300 °C.

A promising Ni-Fe double hydroxide fiber electrode for application of flexible woven-supercapacitor and wastewater decolorization

Textile-based supercapacitors are ideal energy supply equipment for intelligent wearable products. Apart from the further enhanced energy storage property, the poor bending resistance and air permeability also compromise their electrochemical performance in practical use. Based on traditional textile technology, the supercapacitors woven by fibrous electrodes promise to combine both electrochemical and wearable performances. Herein, the carbon fiber-based Ni-Fe double hydroxide electrode (NiFe@NiFeDH/CF) with uniform morphology has been obtained through a facile route of palladium-free electroless plating coupled electrooxidation. By controlling Fe 2+ content in the plating baths, the interwoven nanosheets with small intervals and large crystal spacing could be designed, which provided low diffusion resistance for electrolyte ions and adequate active sites for energy storage. Subsequently, the all-solid-state asymmetric textile supercapacitors (wSC-NF//CY) were fabricated by weaving techniques with NiFe@NiFeDH/CF as positive electrode and carbon yarns as the negative electrode. Benefit from the better electrochemical property of NiFe@NiFeDH/CF, the wSC-NF//CY owned unexpected excellent energy storage performance that at the power density of 9.0 W cm −2 the energy density could reach 26.8 mW h cm −2 . Additionally, with the help of fabric structure, the wSC-NF//CY could be integrated into different materials to accommodate curved human bodies or other non-flat surfaces. Moreover, the NiFe@NiFeDH/CF could also be used to decolorize sewage with an electro-Fenton reaction under a small voltage. Thus, this work constituted a breakthrough on multifunctional energy storage materials and their eco-friendly and sustainable usage. • The fiber electrode was prepared by electroless plating coupled electrooxidation. • Fabric based supercapacitor with plain weave structure was obtained by weaving. • The supercapacitor owned unexpectedly excellent electrochemical performance. • The fiber electrode could also treat colored wastewater under a small voltage.

Fabric-Reinforced Cementitious Matrix (FRCM) Carbon Yarns with Different Surface Treatments Embedded in a Cementitious Mortar: Mechanical and Durability Studies.

Nowadays, FRCM systems are increasingly used for the strengthening and retrofitting of existing masonry and reinforced concrete structures. Their effectiveness strongly depends on the bond that develops at the interface between multifilament yarns, which constitute the reinforcing fabric, and the inorganic matrix. It is well known that fabric yarns, especially when constituted by dry carbon fibers, have poor chemical-physical compatibility with inorganic matrices. For this reason, many efforts are being concentrated on trying to improve the interface compatibility by using different surface treatments on multifilament yarns. In this paper, three different surface treatments have been considered. The first two involve yarn pre-impregnation with flexible epoxy resin or nano-silica coating, while the third one involves a fiber oxidation process. Uniaxial tensile tests were carried out on single carbon yarns to evaluate tensile strength, elastic modulus and ultimate strain before and after surface treatments, and also after yarn exposure to accelerated artificial aging conditions (1000 h in saline or alkaline solutions at 40 °C), to evaluate their long-term behavior in aggressive environments. Pull-out tests on single carbon yarns embedded in a cementitious mortar were also carried out, under normal environmental conditions and after artificial exposure. Epoxy proved to be the most effective treatment, by increasing the yarn tensile strength of 34% and the pull-out load of 138%, followed by nano-silica (+9%; +40%). All surface treatments were shown to remain effective even after artificial environmental exposures, with a maximum reduction of yarn tensile strength of about 13%.

Interlayer Defect Detection in Intra-Ply Hybrid Composite Material (GF/CF) Using a Capacitance-Based Sensor.

Combining two types of reinforcement fiber in a common matrix may lead to different failure modes such as micro-cracks between the layers when the structure is subjected to lower stress levels. Real-time damage detection should be integrated into the hybrid composite structure to provide structural integrity and mitigate this problem. This paper outlines the working mechanisms and the fabrication of an integrated capacitive sensor in an intra-ply hybrid composite (2 × 2 twill weave). Uniaxial tensile and flexural tests were conducted to characterize the proposed sensor and provide self-sensing functionality (smart structure). The sensitivity and repeatability of the capacitive sensor were measured to be around 1.3 and 185 µΔC/Co, respectively. The results illustrate that onset of damage between layers can be detected by in situ monitoring. It can be seen that the initial damage was detected at the turning point where the relative change in capacitance begins to reduce while the load increases. Finite element modeling was also constructed to analyze the test results and explain the reasons behind the turning point. It was shown that the carbon yarns experienced high transverse shear stress (τxz) in the crimp region, leading to inter-fiber cracks.

Simultaneous Integration of Continuous Mineral-Bonded Carbon Reinforcement Into Additive Manufacturing With Concrete

3D concrete printing is becoming more and more popular, not only in research but also in practice of construction. One of the main challenges however remains the integration of reinforcement. This publication focuses on the use of continuous fibers for this purpose. The special feature of the new type of carbon yarns applied is the mineral impregnation used instead of the conventional polymer one. Such reinforcement not only yields excellent mechanical properties, but also offers many advantages, specifically with respect to processing flexibility and is therefore very well suited for additive manufacturing. The concrete for 3D printing to be reinforced with such yarns must meet particular requirements, especially when the finest concrete filaments are printed. This is also a subject of the article at hand.

TiO2 anchored carbon fibers as non-invasive electrochemical sensor platform for the cortisol detection

An electrochemical immunosensor integrated on carbon yarns for non-invasive detection of cortisol is reported. The carbon yarns were integrated with TiO2 nanostructures for immobilizing cortisol specific antibodies. While the integration of TiO2 nanostructure was characterized using XRD and FE-SEM, the biorecognition of cortisol by antibodies modified yarns was investigated using voltammetric techniques (CV and DPV). The carbon yarn based immunosensor showed good sensitivity and is responsive over a broad-range of cortisol concentration (10 fg to 1 μg/mL). The efficacy of the cortisol sensing platform towards cortisol estimation in human sweat was evaluated and validated using commercially available chemiluminescence assay. The results demonstrated the excellent sensing performance of the TiO2 carbon fiber based flexible immunosensor system and its great potential in developing non-invasive POC sensor for human sweat cortisol detection.

Carbon Yarn-Ball-Entangled SiO2 Anode with Excellent Electrochemical Performance for Lithium-Ion Batteries.

Various nanoscale SiO2 and their composites have demonstrated superior electrochemical performance as anodes for lithium-ion batteries. However, both the battery production and real applications require the integration of nanoscale SiO2 into micrometer-sized secondary particles while preserving their excellent stability and conductivity, which remains a great challenge. In this work, a unique carbon yarn-ball structure is successfully synthesized that entangles nanoscale SiO2 together to build a micrometer-sized secondary particle. The hook-like carbon wires closely adhere to individual SiO2 nanoparticles, which constitute the basic unit of the yarn-ball structure. The entangled carbon wires create a network of electron conduction highways for SiO2 , and the yarn-ball structure provides a resilient 3D matrix that can effectively buffer the anisotropic volume changes of SiO2 during Li ion insertion/extraction. Under 0.1 A g-1 , the carbon yarn-ball-entangled SiO2 can deliver a 1297 mAh g-1 discharge capacity with a small irreversible capacity of 82 mAh g-1 . The entangled carbon yarn ball firmly maintains its structural integrity during high-rate cycling (1 A g-1 ), which gives rise to a large accessible capacity (709 mAh g-1 , 90.7% retention for 500 cycles), superior coulombic efficiency (>99.9%), and excellent structural stability.

Porous PDMS conformable coating for high power output carbon fibers/ZnO nanorod-based triboelectric energy harvesters

A new method for depositing PDMS directly onto conductive carbon yarns is proposed to produce Triboelectric Nanogenerator Yarns (TENG yarns) that can serve as the basic building blocks for energy scavenging wearables. The in-situ PDMS curing method described in this study allows the fast formation of a uniform thick coating over conductive surfaces regardless of their roughness. Single-electrode configuration TENG yarns are developed and their electrical output is optimized by precisely adjusting the PDMS layer thickness and by changing the chemical and physical nature of the carbon fiber (CF) yarns’ surface. Functionalizing the CF yarns’ surface with ZnO rods combined with porous PDMS coating can enhance their electrical output. The best results are achieved using this type of TENG yarns with an average diameter of 1.74 mm, which can be obtained after only 3 min of PMDS deposition by “in-situ” curing method. A maximum of 72 V peak-to-peak and 10 µA (74.1 µW cm−2 of power density with a load resistance of 20 MΩ) is reached when applying an impact force of 600 N to a set of five TENG yarns connected in parallel. The output is stable even after 10,000 cycles and this set of TENG yarns is also able to light at least 28 LEDs when tapping by hand, proving a contribute towards the development of basic building blocks to power the future generation of wearables.

Realizing High‐Energy and Stable Wire‐Type Batteries with Flexible Lithium–Metal Composite Yarns

AbstractHigh‐capacity and omnidirectionally flexible wire‐type lithium (Li)–metal batteries represent a feasible technology for the realization of electronic textiles. However, the use of commercially available Li–metal wires as anodes nowadays confronts many electrochemical and mechanical issues such as dendrite formation, low yield strength, and poor fatigue resistance. Here, a flexible and stable Li–metal composite yarn (LMCY) is designed via a fast capillary filling of molten Li into metallic carbon yarn for fabricating high‐energy‐density and long‐lasting wire‐type Li–metal batteries. LMCY shows outstanding electrochemical cyclic stability, mechanical strength, flexibility, and durability. Pairing lithium–iron phosphate (LFP) with the LMCY as anode results in a foldable LFP||Li full cell that delivers a high energy density over 290 Wh L−1 and a long lifetime over 800 cycles with a capacity retention of over 50% after 750 charge/discharge cycles. The seamless integration of this wire‐shape LFP||Li cell with commercial textiles is demonstrated as a built‐in power supply to wearable electronics, while maintaining the excellent breathability of the textiles. LMCYs are also adaptable to other high‐performance wire‐type batteries, such as lithium–sulfur battery.