Scalable one-step wet-spinning of triboelectric fibers for large-area power and sensing textiles

Textile-based electronic devices have attracted increasing interest in recent years due to their wearability,breathability,comfort.Among them,textile-based triboelectric nanogenerators(T-TENGs)exhibit remarkable advantages in mechanical energy harvesting and self-powered sensing.However,there are still some key challenges to the development and application of triboelectric fibers(the basic unit of T-TENG).Scalable production and large-scale integration are still significant factors hindering its application.At the same time,there are some difficulties to overcome in the manufacturing process,such as achieving good stretchability and a quick production,overcoming incompatibility between conductive and triboelectric materials.In this study,triboelectric fibers are produced continuously by one-step coaxial wet spinning.They are only 0.18 mm in diameter and consist of liquid metal(LM)core and polyurethane(PU)sheath.Due to the good mechanical properties between them,there is no interface incompatibility of the triboelectric fibers.In addition,triboelectric fibers can be made into large areas of T-TENG by means of digital embroidery and plain weave.The T-TENGs can be used for energy harvesting and self-powered sensing.When they are fixed on the forearm can monitor various strokes in badminton.This work provides a promising strategy for the large-scale fabrication and large-area integration of triboelectric fibers,promotes the development of wearable T-TENGs.

One-step and Continuous Fabrication of Coaxial Piezoelectric Fiber for Sensing Application

Although there has been rapid advancement in piezoelectric sensors,challenges still remain in developing wearable piezoelectric sensors by a one-step,continuous and environmentally friendly method.In this work,a 1D flexible coaxial piezoelectric fiber was directly fabricated by melt extrusion molding,whose core and sheath layer are respectively slender steel wire(i.e.,electrode)and PVDF(i.e.,piezoelectric layer).Moreover,such 1D flexible coaxial piezoelectric fiber possesses short response time and high sensitivity,which can be used as a selfpowered sensor for bending and vibration sensing.More interestingly,such 1D flexible coaxial piezoelectric fiber(1D-PFs)can be further endowed with 3D helical structure.Moreover,a wearable and washable motion monitoring system can be constructed via braiding such 3D helical piezoelectric fiber(3D-PF)into commercial textiles.This work paves a new way for developing 1D and 3D piezoelectric fibers through a one-step,continuous and environmentally friendly method,showing potential applications in the field of sensing and wearable electronics.

Highly stretchable kirigami-patterned nanofiber-based nanogenerators for harvesting human motion energy to power wearable electronics

Wearable electronics are advancing towards miniaturization and flexibility.However,traditional energy supply methods have largely hindered their development.An effective solution to this problem is to convert human mechanical energy into electricity to power wearable electronic devices.Therefore,it is greatly attractive to design flexible,foldable and even stretchable energy harvesting devices.Herein,we use the electrospinning and kirigami approach to develop a type of highly stretchable kirigami-patterned nanofiber-based triboelectric nanogenerator(K-TENG).Due to its innovative structural design,the K-TENG can achieve a tensile strain of 220%,independent of the tensile properties of the material itself.When a person swings their arms,the K-TENG fixed to the clothing can convert mechanical energy from human movement into electrical energy.The produced electricity can directly drive 50 LED lights and a digital watch,or be stored in a lithium battery to charge the smartwatch and smartphone,respectively.This study employs a new method to fabricate a stretchable triboelectric nanogenerator and demonstrates its promising applications in wearable power technology.

Cu_(3)P nanoparticles confined in nitrogen/phosphorus dual-doped porous carbon nanosheets for efficient potassium storage

Immobilizing primary electroactive nanomaterials in porous carbon matrix is an effective approach for boosting the electrochemical performance of potassium-ion batteries (PIBs) because of the synergy among functional components. Herein, an integrated hybrid architecture composed of ultrathin Cu_(3)P nanoparticles (~20 nm) confined in porous carbon nanosheets (Cu_(3)P⊂NPCSs) as a new anode material for PIBs is synthesized through a rational self-designed self-templating strategy. Benefiting from the unique structural advantages including more active heterointerfacial sites, intimate and stable electrical contact, effectively relieved volume change, and rapid K^(+) ion migration, the Cu_(3)P⊂NPCSs indicate excellent potassium-storage performance involving high reversible capacity, exceptional rate capability, and cycling stability. Moreover, the strong adsorption of K^(+) ions and fast potassium-ion reaction kinetics in Cu_(3)P⊂NPCSs is verified by the theoretical calculation investigation. Noted, the intercalation mechanism of Cu_(3)P to store potassium ions is, for the first time, clearly confirmed during the electrochemical process by a series of advanced characterization techniques.

Conductivity of Poly(methyl methacrylate)/Polystyrene/Carbon Black and Poly(ethyl methacrylate)/Polystyrene/Carbon Black Ternary Composite Films

Poly(methyl methacrylate)(PMMA)/polystyrene(PS)/carbon black(CB)and poly(ethyl methacrylate)(PEMA)/PS/CB ternary composite films were obtained using solution casting technique to investigate double percolation effect.In both PMMA/PS/CB and PEMA/PS/CB ternary composite films,the CB particles prefer to locate into PS phase based on the results of calculating wetting coefficient,which is also confirmed by SEM images.The conductivity of the films was investigated,and the percolation threshold(￠c)of both ternary composite films with different polymer blend ratios was determined by fitting the McLachlan GEM equation.Conductivity of PMMA/PS/CB ternary composite films showed a typical double percolation effect.However,due to the double emulsion structure of PEMA/PS polymer blends,the PEMA/PS/CB ternary composite films(PEMA/PS=50/50)showed a higher￠c,even CB only located in PS phase,which conflicts with the double percolation effect.A schematic diagram combined with SEM images was proposed to explain this phenomenon.

Polymer composites designed with 3D fibrous CNT“tracks”achieving excellent thermal conductivity and electromagnetic interference shielding efficiency

The rapid improvement in the running speed,transmission efficiency,and power density of miniaturized devices means that multifunctional flexible composites with excellent thermal management capability and high electromagnetic interference(EMI)shielding performance are urgently required.Here,inspired by the fibrous pathways of the human nervous system,a“core–sheath”fibers structured strategy was proposed to prepare thermoplastic polyurethane/polydopamine/carbon nanotube(TPU/PDA/CNT)composites film with thermal management capability and EMI shielding performance.Firstly,TPU@PDA@CNT fibers with CNT shell were prepared by a facile polydopamine-assisted coating on electrospun TPU fibers.Subsequently,TPU/PDA/CNT composites with three-dimensional(3D)fibrous CNT“tracks”are obtained by a hot-pressing process,where CNTs distributed on adjacent fibers are compactly contacted.The fabricated TPU/PDA/CNT composites exhibit a high in-plane thermal conductivity(TC)of 9.6 W/(m·K)at low CNT loading of 7.6 wt.%.In addition,it also presents excellent mechanical properties and excellent EMI shielding effectiveness of 48.3 dB as well as multi-source driven thermal management capabilities.Hence,this study provides a simple yet scalable technique to prepare composites with advanced thermal management and EMI shielding performance to develop new-generation wireless communication technologies and portable intelligent electronic devices.

Interface engineering and heterometal doping Mo-NiS/Ni(OH)_(2)for overall water splitting

Developing cost-effective,efficient and bifunctional electrocatalysts is vital for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)application.The catalytic activity of electrocatalysts could be optimized by reasonable electronic structure regulation and increasing active sites.Herein,we report the design and fabrication of Mo-doped nickel sulfide/hydroxide heterostructures(Mo-NiS/Ni(OH)_(2))as a multisite water splitting catalyst via straightforward solvothermal and in-situ growth strategy.Based on foreign metal doping and interface interaction,the electronic conductivity of heterostructures is improved and the charge transfer kinetics across the interface is promoted,which are demonstrated by the theoretical calculations.Mo-NiS/Ni(OH)_(2)electrocatalyst is endowed with high electrocatalytic performance for water splitting and remarkable durability in alkaline electrolyte.It exhibits the low overpotential of 186 and 74 mV at 10 mA·cm^(-2)for OER and HER,respectively.Importantly,after continuously working for 50 h,the current densities of HER and OER both show negligible degeneration.Even,the resulting Mo-NiS/Ni(OH)_(2)better catalyzes water splitting,yielding a current density of 10 mA·cm^(-2)at a cell voltage of 1.5 V and outperforming Pt/C-IrO2 couple(1.53 V).This result demonstrates that transition metal doping and heterogeneous interface engineering are useful means for conventional catalyst design.

Synthesis of carbon nanotubes-supported porous silicon microparticles in low-temperature molten salt for highperformance Li-ion battery anodes

Silicon-based materials has attracted attention as a promising candidate for lithium-ion batteries(LIBs)with high energy density.However,severe volume variation,pulverization,and poor conductivity hindered the development of Si based materials.In this study,porous Si microparticles supported by carbon nanotubes(p-Si/CNT)are fabricated through simple molten salt assisted dealloying process at low temperature followed by acid treatment.The ZnCl2 molten salt not only provides the liquid environment to enhance the reaction,but also participates the dealloying process and works as template for porous structure when removes by acid treatment.Additionally,distribution of defect sites in CNTs also increases after molten salt process.Density function theory(DFT)calculations further prove the defects could improve the adsorption of Li+.The participation of CNTs can also contribute to the reaction kinetics and retain the integrity of the electrode.As expected,the p-Si/CNT anode manifests enhanced lithium-storage performance in terms of superior cycling stability and good rate capability.The p-Si/CNT//LiCoO_(2) full cell assembly further demonstrates its potential as a prospective anode for high-performance LIBs.

Recent progress,mechanisms,and perspectives for crystal and interface chemistry applying to the Zn metal anodes in aqueous zinc-ion batteries

The need for large-scale electrochemical energy storage devices in the future has spawned several new breeds of batteries in which aqueous zinc ion batteries(AZIBs)have attracted great attention due to their high safety,low cost,and excellent electrochemical performance.In the current research,the dendrite and corrosion caused by aqueous electrolytes are the main problems being studied.However,the research on the zinc metal anode is still in its infancy.We think it really needs to provide clear guidelines about how to reasonably configure the system of AZIBs to realize high-energy density and long cycle life.Therefore,it is worth analyzing the works on the zinc anode,and several strategies are proposed to improve the stability and cycle life of the battery in recent years.Based on the crystal chemistry and interface chemistry,this review reveals the key factors and essential causes that inhibit dendrite growth and side reactions and puts forward the potential prospects for future work in this direction.It is foreseeable that guiding the construction of AZIBs with high-energy density and long cycle life in various systems would be quite possible by following this overview as a roadmap.

Facile Synthesis of Fe-based MOFs(Fe-BTC) as Efficient Adsorbent for Water Purifications

Fe-based metal-organic frameworks(Fe-BTC) were successfully synthesized in a large scale by using a simple one-pot method at room temperature. To understand its composition, texture and morphology, the as-synthesized material was analyzed systematically. Moreover, based on the adsorption property for anionic organic dyes(methyl orange, Congo red), cationic organic dves(methylene blue, rhodamine B) and heavy metal ions(Pb^2+) in aqueous solutions, it was revealed that the obtained Fe-BTC showed excellent capacities and adsorption rates tor different adsorbates. Besides the general adsorption eftect derived from the numerous pores and large specific surface area, the electrostatic forces and Л-Л interactions between benzene rings are believed to play significant roles in the large uptakes of this Fe-BTC sample. And the existence of mesopores in Fe-BTC might accelerate the adsorption.

Facile fabrication of highly durable superhydrophobic strain sensors for subtle human motion detection

Endowing strain sensors with superhydrophobicity is of great importance to guarantee their long-term service under harsh environments(such as wet,acid,alkali and salt atmospheres),whereas,the development of superhydrophobic strain sensors remains a great challenge.Herein,we realized a superhydrophobic and highly sensitive sensor for subtle human motion detection by designing a superhydrophobic and electrically conductive coating on cotton textile,via a facile drop-coating method.The resultant strain sensor showed a large water contact angle of 161.3°and a low sliding angle of 3.8°The superhydrophobic characteristics can keep almost unchanged even after undergoing 1000 peeling cycles,1000 stretchingrelease cycles,and 1000 bending-releasing cycles,revealing its excellent mechanical robustness.High sensitivity with the maximum gage factor of 169 was achieved for the strain sensor under a small strain of0–10%,and the sensing performance also showed well durability.Moreover,our sensor can effectively detect various subtle human physiological signals and body motions even under harsh conditions.These admirable features make the sensor promising applications in wearable electronics,personalized health monitoring,sound recognition,and so on.

Immobilizing VN ultrafine nanocrystals on N-doped carbon nanosheets enable multiple effects for high-rate lithium-sulfur batteries

The exploitation of new sulfiphilic and catalytic materials is considered as the promising strategy to overcome severe shuttle effect and sluggish kinetics conversion of lithium polysulfides within lithium-sulfur batteries.Herein,we design and fabricate monodisperse VN ultrafine nanocrystals immobilized on nitrogen-doped carbon hybrid nanosheets(VN@NCSs)via an one-step in-situ selftemplate and self-reduction strategy,which simultaneously promotes the interaction with polysulfides and the kinetics of the sulfur conversion reactions demonstrated by experimental and theoretical results.By virtue of the multifunctional structural features of VN@NCSs,the cell with ultrathin VN@NCSs(only 5 pm thickness)modified separator indicates improved electrochemical performances with long cycling stability over 1,000 cycles at 2 C with only 0.041%capacity decay per cycle and excellent rate capability(787.6 mAh g^(-1) at 10 C).Importantly,it delivers an areal reversible capacity of 3.71 mAh cm^(-2) accompanied by robust cycling life.

In-situ embedding CoTe catalyst into 1D-2D nitrogen-doped carbon to didirectionally regulate lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries have been widely investigated attributed to their advantages of high energy density and cost effectiveness.However,it is still limited by the uncontrolled shuttle effect of the sulfur cathode and the promiscuous dendrite growth over the lithium anode.To handle the above issues,the highly conductive CoTe catalyst is precisely loaded onto nitrogendoped nanotube and graphene-like carbon(CoTe NCGs),which is employed as a bi-functionally integrated host.On the lithium anode,the CoTe NCGs with excellent lithiophilic property effectively regulate the uniform deposition of lithium and achieve the effect of suppressing the disorderly growth of lithium dendrites.On the sulfur cathode,the electrochemical conversion of lithium polysulfides(LiPSs)is catalyzed to mitigate the notorious shuttle effect.In view of the bifunctionality of CoTe NCGs,the assembled full cell can be steadily stable even for 800 cycles at a high rate of 2 C,and the capacity decay rate is only 0.05%per cycle.The areal capacity of 6.0 mAh·cm^(−2) is well retained after 50 cycles under the conditions of high sulfur loading,poor electrolyte(a low electrolyte-to-sulfur ratio,E/S=4.2),and low negative to positive capacity ratio(N/P=1.6:1).