Conductive Network Research Articles

Construction of multiple interpenetrati ng network electric field-assisted healing hydrogel composite damage-resistant membrane

Inspired by the intrinsic self-healing ability of organisms, this study proposes to incorporate healing properties into separation membranes that are susceptible to physical damage during installation, operation, maintenance, and cleaning. The polyacrylic acid (PAA) hydrogel-modified layer was first obtained by in situ cross-linking and free radical polymerization in this research. After that, the construction of multiple interpenetrating three-dimensional (3D) network hydrogel-modified layers was realized via inserting amininated carbon nanotubes (CNTs-NH2) and Fe3+. Under the external effect of the electric field, the reversible dynamic linkage bonded in the conductive network constructed by CNTs-NH2 and Fe3+ benefited the rearrangement and diffusion of PAA molecular chains at the fractured interface. The dye separation performance of the composite membrane was restored to ca. 90 % of the initial level without affecting the dynamic operation after damage. The hydrogel-modified layer can be structurally stabilized for as long as 100 days. The Fe3+/CNTs-NH2/PAA/PES hydrogel composite membrane maintained a pure water flux of as high as 124.66 L m−2 h−1∙bar−1. This coating also exhibited excellent electrical conductivity (714.33 Ω/sq), mechanical strength (4.31 Mpa), repair, and screening capabilities. It provides a theoretical basis for achieving industrial scale-up and demonstrates good application prospects and empowerment potential.

Enhancing micro-scale SiOx anode durability: Electro-mechanical strengthening of binder networks via anchoring carbon nanotubes with carboxymethyl cellulose

With the increasing prevalence of lithium-ion batteries (LIBs) applications, the demand for high-capacity next-generation materials has also increased. SiOx is currently considered a promising anode material due to its exceptionally high capacity for LIBs. However, the significant volumetric changes of SiOx during cycling and its initial Coulombic efficiency (ICE) complicate its use, whether alone or in combination with graphite materials. In this study, a three-dimensional conductive binder network with high electronic conductivity and robust elasticity for graphite/SiOx blended anodes was proposed by chemically anchoring carbon nanotubes and carboxymethyl cellulose binders using tannic acid as a chemical cross-linker. In addition, a dehydrogenation-based prelithiation strategy employing lithium hydride was utilized to enhance the ICE of SiOx. The combination of these two strategies increased the CE of SiOx from 74% to 87% and effectively mitigated its volume expansion in the graphite/SiOx blended electrode, resulting in an efficient electron-conductive binder network. This led to a remarkable capacity retention of 94% after 30 cycles, even under challenging conditions, with a high capacity of 550 mA h g−1 and a current density of 4 mA cm−2. Furthermore, to validate the feasibility of utilizing prelithiated SiOx anode materials and the conductive binder network in LIBs, a full cell incorporating these materials and a single-crystalline Ni-rich cathode was used. This cell demonstrated a ∼27.3% increase in discharge capacity of the first cycle (∼185.7 mA h g−1) and exhibited a cycling stability of 300 cycles. Thus, this study reports a simple, feasible, and insightful method for designing high-performance LIB electrodes.

Quasi-1D Conductive Network Composites for Ultra-Sensitive Strain Sensing.

Highly performance flexible strain sensor is a crucial component for wearable devices, human-machine interfaces, and e-skins. However, the sensitivity of the strain sensor is highly limited by the strain range for large destruction of the conductive network. Here the quasi-1D conductive network (QCN) is proposed for the design of an ultra-sensitive strain sensor. The orientation of the conductive particles can effectively reduce the number of redundant percolative pathways in the conductive composites. The maximum sensitivity will reach the upper limit when the whole composite remains only "one" percolation pathway. Besides, the QCN structure can also confine the tunnel electron spread through the rigid inclusions which significantly enlarges the strain-resistance effect along the tensile direction. The strain sensor exhibits state-of-art performance including large gauge factor (862227), fast response time (24ms), good durability (cycled 1000 times), and multi-mechanical sensing ability (compression, bending, shearing, air flow vibration, etc.). Finally, the QCN sensor can be exploited to realize the human-machine interface (HMI) application of acoustic signal recognition (instrument calibration) and spectrum restoration (voice parsing).

Synergistic enhancement of ion/electron transport by ultrafine nanoparticles and graphene in Li2FeTiO4/C/G nanofibers for symmetric Li-ion batteries

Low-cost Fe-based disordered rock salt (DRX) Li2FeTiO4 is capable of providing high capacity (295 mA h g−1) by redox activity of cations (Fe2+/Fe4+ and Ti3+/Ti4+) and anionic oxygen. However, DRX structures lack transport channels for ions and electrons, resulting in sluggish kinetics, poor electrochemical activity, and cyclability. Herein, graphene conductive carbon network permeated Li2FeTiO4 (LFT/C/G) nanofibers are successfully prepared by a facile sol-gel assisted electrospinning method. Ultrafine Li2FeTiO4 nanoparticles (2 nm) and one-dimensional (1D) structure provide abundant active sites and unobstructed diffusion channels, accelerating ion diffusion. In addition, introducing graphene reduces the band gap and Li+ diffusion barrier and improves the dynamic properties of Li2FeTiO4, thus achieving a relatively mild interfacial reaction and reversible redox reaction. As expected, the LFT/C/1.0G cathode delivers a remarkable discharge capacity (238.5 mA h g−1), high energy density (508.8 Wh kg−1), and excellent rate capability (51.2 mA h g−1 at 1.0 A g−1). Besides, the LFT/C/1.0G anode also displays a high capacity (514.5 mA h g−1 at 500 mA g−1) and a remarkable rate capability (243.9 mA h g−1 at 8 A g−1). Moreover, the full batteries based on the LFT/C/1.0G symmetric electrode demonstrate a reversible capacity of 117.0 mA h g−1 after 100 cycles at 50 mA g−1. This study presents useful insights into developing cost-effective DRX cathodes with durable and fast lithium storage.

Ultrafast joule-heating synthesis of FeCoMnCuAl high-entropy-alloy nanoparticles as efficient OER electrocatalysts

High entropy alloys (HEAs), known for their synergistic orbital interactions among multiple elements, have been recognized as promising electrocatalysts for enhancing the sluggish kinetics of oxygen evolution reaction (OER). Despite their potential, the facile and rapid preparation of HEA nanoparticles (NPs) with high electrocatalytic activity remains challenging. Here, we report an ultrafast synthesis of noble-metal-free FeCoMnCuAl HEA NPs loaded on conductive carbon fiber networks using a Joule heating strategy. The prepared HEA NPs exhibited a face-centered cubic (FCC) structure with an average size of approximately 25 ​nm. Synchrotron X-ray absorption fine structure (XAFS) and X-ray photoelectron spectroscopy (XPS) studies were performed to investigate the atomic and electronic structures of the HEA NPs, revealing the co-presence of Fe, Co, Mn, Cu and Al elements as well as their different valences across surface and internal regions. The HEA NPs showed remarkable OER performance, exhibiting an overpotential of 280 ​mV at 10 ​mA ​cm−2 and a low Tafel slope of 76.13 ​mV dec−1 in a 1.0 ​M KOH solution with high electrochemical stability, superior to commercial RuO2 electrocatalysts. This work provides a new approach for synthesizing nanoscale noble-metal-free HEA electrocatalysts for clean energy conversion applications on a large-scale basis for practical commercialization.

Ultrafast reaction kinetic of polyaniline in flexible hydrogel electrodes facilitated by graphene ribbons

Abstract By loading energy storage active materials on hydrogel which is inherently flexible, the flexibility of electrode materials can be simply realized, thereby achieving the flexibility of energy storage devices. However, the polymer network that constructs the three-dimensional skeleton of the hydrogel is not conductive, which inhibits the redox ability of the active material. If a high speed conductive structure can be added to the colloidal phase, the performance of the flexible electrode material can be greatly improved. Here, we introduce redox graphene ribbons into the polyvinyl alcohol hydrogel loaded with polyaniline. The in situ three-dimensional conductive graphene network greatly enhanced the conductivity of the hydrogel electrode, thus increasing the specific capacitance to as high as 1117 F g−1 at 2 mg cm−2 mass loading, with a retention ratio of 66.96% from 0.5 A g−1 to 20 A g−1. These highlighted properties enable the PRP hydrogel as an electrode for flexible supercapacitors, which provides a promising possibility for the practical application of wearable electronics.

Physical properties and anisotropy of sandstone during freeze-thaw cycle under unidirectional constraint

To investigate the evolution of physical properties of sandstone under unidirectional constraint during freeze-thaw cycles, an experimental device was specifically designed. Unidirectional constraint freeze-thaw tests were performed on sandstone specimens. The study analyzed variations in the dry mass, saturated mass, and longitudinal wave velocity of the sandstone both before and after undergoing freeze-thaw cycles, as well as examining the evolution of resistivity throughout the process. Results revealed that an increase in the number of freeze-thaw cycles leads to a gradual increase in the saturated mass of sandstone, while its dry mass consistently decreases, irrespective of whether it is subjected to constraint or not. The change rates of both dry mass and saturated mass were found to be significantly lower under unidirectional constraint compared to that without constraint. With more freeze-thaw cycles, a decline in longitudinal wave velocity was noted. Under unconstrained conditions, no significant direction dependence in longitudinal wave velocity was detected. However, under unidirectional constraint, there was a smaller decrease in the longitudinal wave velocity along the direction of constraint compared to other directions. This indicates that constraint mitigates frost heave damage. In the temperature rise and maintenance stages, resistivity initially dropped, then increased prior to stabilizing at a constant value. Conversely, in temperature decrease and maintenance stages, resistivity first rose, then dipped before ultimately rising again. Temperature primarily influenced resistivity by affecting the ion movement velocity within pore water and the connectivity of the conductive network.

Multifunctional strain sensor with adjustable conductive network for wearable applications

AbstractWearable sensors based on nanomaterials have recently elicited keen research interest and potential for a new range of flexible devices. This paper presents a simple method for the preparation of laser‐induced porous graphene (LIG) and discusses its application in monitoring human vital signs. LIG formed on a polyimide (PI)/polydimethylsiloxane (PDMS) composite material exhibits inherent high stretchability (over 30%), eliminating the need for transfer processes used in LIG prepared by laser scribing on PI films. LIG/CuSO4 composite materials, with different concentrations of Cu particles, show tunable mechanical and electronic properties based on laser‐induced graphene. The fabricated LIG demonstrates good cyclic stability and a nearly linear resistance response to tensile strain, making it suitable for wearable electronic devices, the maximum strain value and linear response to applied strain from 3% to 79%. The sensor exhibits a fast response time and high sensitivity, enabling real‐time detection of human pulse, joint motion, and complex dynamics. The multifunctionality advantages of LIG flexible sensor offer potential applications in next‐generation wearable electronics.

Spider silk inspired ultrafine carbon nanotubes-crosslinked porous carbon fibers for Zn-air batteries

There is a critical need for the development of low-cost, highly efficient, and stable bifunctional oxygen electrocatalysts for the advancement of Zn-air battery (ZAB). This study presents an Fe-, Ni-, and N-co-doped porous carbon material (FeNiN-CF-15) synthesized through the pyrolysis of a mixture combining the melamine and electrospun fibers. This material comprises carbon fiber substrates and spider silk-like ultrafine carbon nanotubes (CNTs) catalytically grown from FeNi alloys. With a high N doping level (12.9 at%), large specific surface area (385.18 m2 g−1), and conductive carbon network composed of CNTs, the new electrocatalyst exhibits outstanding bifunctional oxygen electrocatalytic performances. Specifically, it achieves a half-wave potential of 0.853 V for oxygen reduction reaction (ORR) and 1.571 V for oxygen evolution reaction (OER) at 10 mA cm−2. The exceptional ORR/OER electrocatalytic activity enables the FeNiN-CF-15-based liquid ZAB to deliver a high initial energy efficiency of 62.12 %, narrow charging/discharging voltage gap of 0.742 V, and robust cycling stability within 960 cycles for 320 h at 5 mA cm−2. Additionally, the reported electrocatalyst is proven competent for use in a flexible ZAB.

Controllable Synthesis and Growth Mechanism of Cracked Cowpea-Like NCNT Encapsulated with Fe3N Nanoparticles for High-Performance Anode Material in Lithium-Ion Batteries

Fe3N nanocrystals embedded in cracked N-doped carbon nanotubes (Fe3N@NCNT) with a cowpea-like shape are innovatively prepared by metal-catalyzed graphitization and nitridization processes based on melamine and FeC2O4 precursor. The new in-situ synthesis strategy is proved to be effective to open the NCNT using a migratory metal carbide nanocatalyst via expansion effect and fabricate a metal nitride embedded NCNT with fully active ingredients. The detailed tip-growth mechanism of cracked NCNT with latitudinal-longitudinal graphene layers is studied by in-situ XRD analysis of the phase evolution of melamine and FeC2O4, and ex-situ SEM/TEM investigation of the topography correlation of NCNT and Fe3C floating catalyst. The Fe3N@NCNT microclews based anodes have a moderate carbon content of 35.45 wt%, electroactive NCNT conductive network, abundant microcracks and an open short-cavity system, showing a stable discharge capacity of 667 mAh g−1 at 0.1C, outstanding rate capability of 448 mAh g−1 at 5C and remarkable long-term cycling stability of 546 mAh g−1 after 600 cycles at 1C. The combined good electronic/ionic conductivity of cracked NCNT and robust mechanical stability of geometrically confined Fe3N nanoparticles contribute to the excellent redox activities, stabilized solid-electrolyte-interphase film and cycling durability of Fe3N@NCNT.

Universal design of three-dimensional porous graphene-iron based promotors for kinetically rationalized lithium-sulfur chemistry

Lithium-sulfur (Li-S) batteries are widely deemed to be one of the most potential candidates for future secondary batteries because of their remarkable energy density. Nevertheless, notorious polysulfide shuttling and retarded sulfur reaction kinetics pose significant obstacles to the further application of Li-S batteries. While rationally designed highly active electrocatalysts can facilitate polysulfide conversion, the universal and scalable synthesis strategies need to be developed. Herein, a universal synthetic strategy to construct a series of three-dimensional (3D) porous graphene-iron (3DGr-Fe) based electrocatalysts involving 3DGr-FeP, 3DGr-Fe3C, and 3DGr-Fe3Se4 is exploited for manipulating the Li-S redox reactions. It has been observed that the implementation of a 3D porous Gr architecture leads to the well-designed conductive networks, while the uniformly dispersed iron nanoparticles introduce an abundance of active sites, fostering the lithium polysulfide conversion, thereby bolstering the overall electrochemical performance. The Li-S battery with the 3DGr-Fe based electrocatalyst exhibits remarkable capacity retention of 94.8% upon 100 times at 0.2 C. Moreover, the soft-packaged Li-S pouch cell based on such a 3DGr-Fe electrocatalyst delivers superior capacity of 1060.71 mA h g−1 and guarantees for the continuous 30 min work of fan toy. This investigation gives comprehensive insights into the design, synthesis, and mechanism of 3DGr-Fe based electrocatalysts with high activity toward efficient and durable Li-S batteries.

Constructing Electronic/Ionic‐Conductive Hydrogel with Soft Compliance and High Conductivity as Flexible Strain Sensor

Flexible sensors are garnering substantial interests for various promising applications, including medical electronics, environmental monitoring, and wearable devices. Developing a flexible sensor with high compliance, high sensitivity, and high reliability through the construction of a novel composite conductive hydrogel based on the synergistic enhancement effect of conductive polymers and metal ions is a remarkable achievement. Herein, an electronic/ionic‐conductive double network hydrogel (polypyrrole (PPy)/carboxymethyl cellulose (CMC)‐Al3+/polyvinyl alcohol (PVA)) with soft compliance, highly conductivity, and stability is presented. Moreover, owing to the synergistic reinforcement effect of the relatively immobilized “islands” of PPy particles and large amounts of movable “bridges” of aluminum ions (Al3+) within the double network hydrogel, the as‐optimized PPy/CMC‐Al3+/PVA composite gels exhibit excellent conductivity (σ = 3.47 ± 0.25 S m−1) and mechanical properties (E = 18.53 ± 0.67 kPa). Furthermore, it has been developed as strain sensors with relatively high linear sensitivity (gauge factor = 2.58) within a broad linearity range (0–400%). It can also be served as a monitoring devices for subtle physiological signals emanating from various parts of the human body. The robust sensor has great potential to be developed as wearable electronic devices and applied in healthcare monitoring fields.

The Influence of Molecular Weights on Dispersion and Thermoelectric Performance of Alkoxy Side-Chain Polythiophene/Carbon Nanotube Composite Materials.

In the development of wearable electronic devices, the composite modification of conductive polymers and single-walled carbon nanotubes (SWCNTs) has become a burgeoning research area. This study presents the synthesis of a novel polythiophene derivative, poly(3-alkoxythiophene) (P3(TEG)T), with alkoxy side chains. Different molecular weight variants of P3(TEG)T (P1-P4) were prepared and combined with SWCNTs to form composite materials. Density functional theory (DFT) calculations revealed a reduced bandgap for P3(TEG)T. Raman spectroscopy demonstrated π-π interactions between P3(TEG)T and SWCNTs, facilitating the dispersion of single-walled carbon nanotubes and the formation of a continuous conductive network. Among the composite films, P4/SWCNTs-0.9 exhibited the highest thermoelectric performance, with a power factor (PF) value of 449.50 μW m-1 K-2. The fabricated flexible thermoelectric device achieved an output power of 3976.92 nW at 50 K, with a tensile strength of 59.34 MPa for P4/SWCNTs. Our findings highlight the strong interfacial interactions between P3(TEG)T and SWCNTs in the composite material, providing an effective charge transfer pathway. Furthermore, an improvement in the tensile performance was observed with an increase in the molecular weight of the polymer used in the composite, offering a viable platform for the development of high-performance flexible organic thermoelectric materials.

Macromolecular PEI-modified carbon nanotubes as multifunctional additives in controlling crystallization and enhancing comprehensive performance of polyamide 6 nanocomposites

Despite the promising potential of carbon nanotubes (CNTs) in polymer nanocomposites, their propensity for aggregation and random dispersion within the polymer matrix poses significant challenges. This study introduces a novel approach to enhance the interfacial properties between the CNTs and the polyamide 6 (PA6) matrix by anchoring the polyethyleneimine (PEI) onto the CNT surfaces. The integration of PEI, with abundant amino groups, provides the high density of nucleation sites, facilitating transcrystallization along the surfaces of the macromolecular polyethyleneimine (PEI) modified CNTs (m-CNTs). This transcrystallization process enhances the physical interactions between the m-CNTs and the PA6 matrix, resulting in the substantial improvements in the mechanical properties of the PA6 nanocomposites. Specifically, as compared to the neat PA6, the PA6/m-CNT nanocomposites exhibited the increase of 131.2 % and 54.3 % in tensile strength and Young's modulus, respectively. Additionally, the intimate contact between the embedded CNTs forms the efficient thermally conductive networks. The robust molecular interactions between the m-CNTs and the PA6 polymer chains promote the highly homogeneous dispersion within the PA6/m-CNT nanocomposites, thereby reducing the thermal resistance. This straightforward and effective method presents a viable strategy for improving the interfacial properties of the CNTs reinforced polymer nanocomposites, offering the extensive potential for the future advancements in the interfacial modifications of the polymer matrix nanocomposites.

Long-distance electron transport in multicellular freshwater cable bacteria.

Filamentous multicellular cable bacteria perform centimeter-scale electron transport in a process that couples oxidation of an electron donor (sulfide) in deeper sediment to the reduction of an electron acceptor (oxygen or nitrate) near the surface. While this electric metabolism is prevalent in both marine and freshwater sediments, detailed electronic measurements of the conductivity previously focused on the marine cable bacteria (Candidatus Electrothrix), rather than freshwater cable bacteria, which form a separate genus (Candidatus Electronema) and contribute essential geochemical roles in freshwater sediments. Here, we characterize the electron transport characteristics of Ca. Electronema cable bacteria from Southern California freshwater sediments. Current-voltage measurements of intact cable filaments bridging interdigitated electrodes confirmed their persistent conductivity under a controlled atmosphere and the variable sensitivity of this conduction to air exposure. Electrostatic and conductive atomic force microscopies mapped out the characteristics of the cell envelope's nanofiber network, implicating it as the conductive pathway in a manner consistent with previous findings in marine cable bacteria. Four-probe measurements of microelectrodes addressing intact cables demonstrated nanoampere currents up to 200 μm lengths at modest driving voltages, allowing us to quantify the nanofiber conductivity at 0.1 S/cm for freshwater cable bacteria filaments under our measurement conditions. Such a high conductivity can support the remarkable sulfide-to-oxygen electrical currents mediated by cable bacteria in sediments. These measurements expand the knowledgebase of long-distance electron transport to the freshwater niche while shedding light on the underlying conductive network of cable bacteria.

Kirkendall Effect-Induced Ternary Heterointerfaces Engineering for High Polarization Loss MOF-LDH-MXene Absorbers.

Heterogeneous interfacial engineering has garnered widespread attention for optimizing polarization loss and enhancing the performance of electromagnetic wave absorption. A novel Kirkendall effect-assisted electrostatic self-assembly method is employed to construct a metal-organic framework (MOF, MIL-88A) decorated with Ni-Fe layered double hydroxide (LDH), forming a multilayer nano-cage coated with Ti3C2Tx. By modulating the surface adsorption of Ti3C2Tx on LDH, the heterointerfaces in MOF-LDH-MXene ternary composites exhibit excellent interfacial polarization loss. Additionally, the Ni-Fe LDH@Ti3C2Tx nano-cage exhibits a large specific surface area, abundant defects, and a large number of heterojunction structures, resulting in excellent electromagnetic wave absorption performance. The MIL-88A@Ni-Fe LDH@Ti3C2Tx-1.0 nano-cage achieves a reflection loss value of -46.7 dB at a thickness of 1.4mm and an effective absorption bandwidth of 5.12 GHz at a thickness of 1.8mm. The heterojunction interface composed of Ni-Fe LDH and Ti3C2Tx helps to enhance polarization loss. Additionally, Ti3C2Tx forms a conductive network on the surface, while the cavity between the MIL-88A core and the Ni-Fe LDH shell facilitates multiple attenuations by increasing the transmission path of internal incident waves. This work may reveal a new structural design of multi-component composites by heterointerfaces engineering for electromagnetic wave absorption.

Synchronously Formed Hetero- and Hollow Core-Branch Nanostructure Toward Wideband Electromagnetic Wave Absorption.

The intrinsic limitation of low electrical conductivity of MoSe2 resulted in inferior dielectric properties, which restricts its electromagnetic wave absorption (EMWA) performances. Herein, a bimetallic selenide of MoSe2/CoSe2@N-doped carbon (NC) composites with hollow core-branch nanostructures are synthesized via the selenization treatment of MoO3 nanorods coated with ZIF-67. By adjusting the mass ratio of ZIF-67 to MoO3, the electromagnetic parameters and morphologies of composites are finely tuned, further ameliorating the impedance matching and EMWA performances. The involvement of NC improves the electronic conductivity of the composites. The synchronously formed heterostructure not only facilitates charge transfer but also leads to the accumulation and uneven distribution of charges, thus enhancing the conductive loss and polarization loss. The hollow core-branch nanostructure provides abundant conductive networks, heterointerfaces, and voids, significantly enhancing the EMWA property. Density functional theory implies that the heterostructures effectively boost charge transport and change charge distribution, which heightens the conductive loss and polarization loss. As a result, the composites demonstrate a minimum reflection loss value of -53.53 dB at 9.04 GHz, alongside a maximum effective absorption bandwidth of 6.32 GHz. This work offers invaluable insights into novel structural designs for future research and applications.

Significantly Promoting the Thermal Conductivity and Machinability of Negative Thermal Expansion Alloy via In Situ Precipitation of Copper Networks.

Rapid advancements in electronic devices yield an urgent demand for high-performance electronic packaging materials with high thermal conductivity, low thermal expansion, and great mechanical properties. However, it is a great challenge for current design philosophies to fulfill all the requirements simultaneously. Here, an effective strategy is proposed for significantly promoting the thermal conductivity and machinability of negative thermal expansion alloy (Zr,Nb)Fe2 through eutectic precipitation of copper networks. The eutectic dual-phase alloy exhibits an isotropic chips-matched thermal expansion coefficient and a thermal conductivity enhancement exceeding 200% compared with (Zr,Nb)Fe2, along with an ultimate compressive strength of 550MPa. The addition of copper reorganizes the composition of (Zr,Nb)Fe2, which smooths the magnetic transition and shifts it toward higher temperature, resulting in linear low thermal expansion in a wide temperature range. The highly fine eutectic copper lamellae construct high thermal conductivity networks within (Zr,Nb)Fe2, serving as highways for heat transfer electrons and phonons. The in situ forming of eutectic copper lamellae also facilitates the mechanical properties by enhancing interfacial bonding and bearing additional stress after yielding of (Zr,Nb)Fe2. This work provides a novel strategy for promoting thermal conductivity and mechanical properties of negative thermal expansion alloys via eutectic precipitation of copper networks.

Induction heating of unidirectional C/PAEK – A thermographic study on eddy current formation

Induction welding is an attractive assembly method for carbon fibre reinforced thermoplastic composites. Parts are heated through the electromagnetic induction of eddy currents in the electrically conductive network of carbon fibres. Such networks rely (partly) on interlaminar contact incidence between the carbon fibres for unidirectional ply-based composites, rendering eddy current formation stochastic. The present study aims to visualise this stochastic behaviour in order to gain deeper insights into the formation of eddy currents. To this end, various laminates were induction heated using a stationary coil while monitoring the heating patterns using a thermal camera. Similar behaviour was then replicated on ply-scale specimens using a strong direct current. The recorded thermograms highlight that eddy currents are predominantly induced along the different fibre directions present in the lay-up. Moreover, it was demonstrated that ply interfaces have a substantial impact on the (re)distribution of current density within the plies.

Constructing nano spinel phase and Li+ conductive network to enhance the electrochemical stability of ultrahigh-Ni cathode

The tungsten with high oxidation states (W6+) had been proved to effectively improve the electrochemical performance of ultrahigh-nickel (Ni ≥ 90 %) cathode materials due to the unique microstructures. However, the exat location and underlying action mechanism of tungsten are still not well-understood, and there have been no reports on in-situ modification from bulk to surface simultaneously for these novel cathode materials. Here, a novel integrated strategy is proposed for in-situ modification of LiNi0.9Co0.09W0.01O2 (NCW). Innovatively, the introduction of nano spinel phase and titanium pinned into the lattice further suppresses the anisotropic variation of unit cell and promotes the lithium-ion migration kinetics within the bulk. Additionally, the Li2TiO3 conductive network enhances migration kinetics across interface and protects the active material against electrolyte erosion. Furthermore, the combination of in-situ analysis and DFT calculation reveals the ordered distribution of tungsten and the suppression effects of titanium on phase transition and cobalt redox. Consequently, the titanium-modified NCW exhibits significantly improved electrochemical performance, such as capacity retention of 93.0 % at 1C after 500 cycles in pouch-type full-cell, along with stable lattice oxygen during operation.