Conductive Network Structure Research Articles

Multi-mechanism response of molten salt-modified MXene with NiCo2O4 nanosheets for enhanced electromagnetic wave absorption performance

To obtain even superior electromagnetic wave (EMW) absorption materials, research is currently focused on composite absorbers. The aim of this work is to prepare composite absorbers with multiple absorption mechanisms using 2D porous Ti3C2Tx MXene as a substrate. Here, porous Ti3C2Tx MXene nanosheets with a large layer spacing were formed through high-temperature molten salt treatment of layered Ti3C2Tx MXene nanosheets. Then, NiCo2O4 nanosheets were anchored onto the porous Ti3C2Tx MXene nanosheets through heat treatment, forming a heterogeneous structure of porous Ti3C2Tx MXene/NiCo2O4 (P-MXene/NiCo2O4). The heterogeneous interface between Ti3C2Tx MXene and NiCo2O4 nanosheets forms strong interfacial polarization, while NiCo2O4 connects the MXene layer to layer forming a conductive network structure. Furthermore, NiCo2O4 nanosheets suppress the self-stacking of porous Ti3C2Tx MXene nanosheets and improve impedance matching. As a result, P-MXene/NiCo2O4 offers excellent EMW absorption performance with a reflection loss (RL) value of − 64.7 dB at a matching thickness of 4.465 mm. This study provides a new idea for pretreating Ti3C2Tx MXene and constructing efficient composite absorbing materials for electromagnetic waves.

A water-based binder with 3D network enabling long-cycle-life silicon/graphite composite anode materials for lithium ion batteries

A binder with strong bonding and 3D network is proven to be beneficial for the electrochemical performance of silicon anode material. Herein, a water-soluble binder with strong adhesion and 3D conductive structure is prepared by a one-pot method. The polymer consists of acrylic acid (AA), acrylamide (AM), and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) forming a terpolymer (PtA), which is grafted to polyvinyl alcohol (PVA) chains to construct a strong hydrogen bonding 3D conductive network structure (PtA/PVA). The polar groups (-COOH and -CONH2) provide strong hydrogen bonding and intermolecular forces for adhesion, while the introduction of lithium salts and sulfonic acid groups provides fast channels for ion transport. In addition, the PVA links with abundant hydroxyl groups, conferring excellent electrochemical performance of silicon/graphite (Si@C 400) composite anodes. As a result, the Si@C 400 anode with the PtA/PVA binder has a reversible capacity of up to 329.8 mAh g−1 at 0.1C, and it shows a prolonged cycle life of 82.0% after 500 cycles at 0.5C. This study provides a promising strategy to design binder for silicon anodes with enhanced electrochemical properties.

Self-supporting and flexible organic potassium terephthalate with controllable carbon layers in K-ion batteries

Herein, we report a self-supporting and flexible K2TP/MWNCTs/C anode material prepared by electrostatic spinning and controlled medium temperature heat treatment in potassium-ion batteries. The results show that the flexible carbon cladding and stably conductive network structure can facilitate the transport of K+ and electron. The as-synthesized K2TP/MWNCTs/C flexible anode can exhibit a high specific capacity of 150.6 mAh g−1 after 100 cycles at a current density of 50 mA g−1. These results are of significant to explore high-performance organic flexible devices.

Fabrication of Flexible FCI/PDMS Electromagnetic Shielding Composites Based on Pulsed Magnetic Field-Induced Alignment

Conductive polymer composites have been utilized in the field of electromagnetic interference (EMI) shielding, albeit requiring a high concentration of conductive fillers to achieve desirable EMI performance. To address this issue and enable the creation of superior EMI shielding composites with reduced filler loadings, this study employed a pulsed magnetic field featuring an amplitude of 0.7 T, a pulse width of 10 μs, and a frequency of 100 Hz to align flaky carbonyl iron (FCI) in poly(dimethylsiloxane) (PDMS). This method resulted in an improved EMI shielding performance of the composites. The outcomes revealed that the pulsed magnetic field effectively controlled the orientation of the FCI, forming a conductive network structure, with the average orientation angle of the FCI reaching 69.3°. The aligned composites exhibited a significant improvement in EMI shielding effectiveness, with the enhancement effect reaching 37.53% and the EMI shielding effectiveness reaching 24.87 dB. Moreover, the flexible tensile properties of the aligned composites were superior to those of the unaligned composites, particularly the elongation at break, which reached 197.46%. The concordance between the theoretical analysis and experimental results affirms the efficacy of the microsecond pulsed magnetic field in enhancing the EMI shielding performance of composite materials. Ultimately, the high-performance, flexible electromagnetic shielding composite materials prepared in this study demonstrate potential for use in advanced electronic equipment.

Construction of the SiC nanowires network structure decorated by MoS2 nanoflowers in porous Si3N4 ceramics for electromagnetic wave absorption

SiC nanowires (SiCnw) are widely combined with ceramic matrix for electromagnetic wave (EMW) absorption due to their good conductive network structure. However, the single loss mechanism limits its further application in the field of EMW absorption. Herein, a novel three-dimensional network of SiCnw decorated by MoS2 nanoflowers with a “flower-branched” structure was synthesized in the pores of porous Si3N4 ceramics (MoS2/SiCnw/Si3N4) by precursor infiltration and pyrolysis combined with hydrothermal reaction. The morphology, pore structure, and dielectric properties of porous MoS2/SiCnw/Si3N4 ceramics were investigated. The interleaved SiCnw within the pore structure provide a large number of growth sites for the MoS2 nanoflowers, ensuring a uniform distribution of MoS2 nanoflowers without agglomeration. Compared with porous SiCnw/Si3N4 ceramics, porous MoS2/SiCnw/Si3N4 ceramics achieve improved microwave absorption performance with an effective absorption bandwidth of 3.50 GHz at a thickness of 2.38 mm and a minimum reflection loss of −70.48 dB at a thickness of 2.10 mm. The excellent EMW absorption performance is attributed to the interfacial polarization loss caused by the MoS2-SiCnw heterogeneous interface, the conduction loss from the SiCnw conductive network, and the defect-induced dipole polarization loss. This work provides new insight into the development of high performance ceramic-based wave absorbing materials.

Self-Stacked 3D Anisotropic BNNS Network Guided by Para-Aramid Nanofibers for Highly Thermal Conductive Dielectric Nanocomposites.

The enhancement of the heat-dissipation property of polymer-based composites is of great practical interest in modern electronics. Recently, the construction of a three-dimensional (3D) thermal pathway network structure for composites has become an attractive way. However, for most reported high thermal conductive composites, excellent properties are achieved at a high filler loading and the building of a 3D network structure usually requires complex steps, which greatly restrict the large-scale preparation and application of high thermal conductive polymer-based materials. Herein, utilizing the framework-forming characteristic of polymerization-induced para-aramid nanofibers (PANF) and the high thermal conductivity of hexagonal boron nitride nanosheets (BNNS), a 3D-laminated PANF-supported BNNS aerogel was successfully prepared via a simple vacuum-assisted self-stacking method, which could be used as a thermal conductive skeleton for epoxy resin (EP). The obtained PANF-BNNS/EP nanocomposite exhibits a high thermal conductivity of 3.66 W m-1 K-1 at only 13.2 vol % BNNS loading. The effectiveness of the heat conduction path was proved by finite element analysis. The PANF-BNNS/EP nanocomposite shows outstanding practical thermal management capability, excellent thermal stability, low dielectric constant, and dielectric loss, making it a reliable material for electronic packaging applications. This work also offers a potential and promotable strategy for the easy manufacture of 3D anisotropic high-efficiency thermal conductive network structures.

High-performance electrode of ZIF-67 metal-organic framework (MOF) loaded laser-induced graphene (LIG) composite for all-solid-state supercapacitor

This work demonstrates a facile and efficient methodology to synthesize a composite material of zeolitic imidazolate frameworks (ZIFs) and laser-induced graphene (LIG). This ZIF-67 loaded LIG composite (ZIF-67/LIG) has been adequately characterized for its morphology and structure, and its electrochemical performance has been specifically examined. As supercapacitors (SCs) electrode material, the ZIF-67/LIG composite exhibits superb electrochemical performance, owing to the inherent high porosity, abundant active sites, large specific surface area of ZIF-67, and the excellent conductive three-dimensional hierarchical porous network structure provided by LIG. In three-electrode system, ZIF-67/LIG composite electrode displays outstanding areal specific capacitance (C A) of 135.6 mF cm−2 at a current density of 1 mA cm−2 with 1 M Na2SO4 aqueous electrolyte, which is far greater than that of pristine LIG (7.7 mF cm−2). Furthermore, the ZIF-67/LIG composite has been fabricated into an all-solid-state planar micro-supercapacitor (MSC). This ZIF-67/LIG MSC exhibits an impressive C A of 38.1 mF cm−2 at a current density of 0.20 mA cm−2, a good cycling stability of 80.3% capacitance retention after 3000 cycles, and a high energy density of 5.29 μWh cm−2 at a power density of 0.1 mW cm−2. All electrochemical results clearly manifest that as-prepared ZIF-67/LIG composite can be a candidate in energy storage field with exciting possibilities.

Three-dimensional (3D) MnMoO4@g-C3N4/CNT hybrid composite electrode for hybrid capacitive deionization

In this work, a hierarchical three-dimensional MnMoO4@g-C3N4/CNT hybrid ternary composite was developed through the facile hydrothermal method. MnMoO4@g-C3N4/CNT and g-C3N4/CNT electrodes were used as cathode and anode to fabricate the hybrid capacitive deionization (HCDI) system. Manganese molybdate (MnMoO4) rods are uniformly intertwined on the three-dimensional (3D) conductive network structure of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) heterojunction in the ternary composite. As-obtained electrode materials of MnMoO4@g-C3N4/CNT and g-C3N4/CNT show the specific capacitance of 252.4 and 89.2 Fg−1, respectively, at 1 Ag−1 in 1 M NaCl solution. Mn element in the MnMoO4@g-C3N4/CNT hybrid induces a reversible redox reaction that selectively intercalates/de-intercalates the Na+-ion in the salt solution, yielding a high salt adsorption capacity of 43.6 mg. g−1 at 1.2 V and 1000 ppm NaCl solution medium. In addition, MnMoO4@g-C3N4/CNT //g-C3N4/CNT-based HCDI cell was recycled for 10 cycles. The system reaches the highest SAC of 42.6 mg. g−1 after 10 consecutive charge–discharge cycles with a retention of 91%, indicating the excellent cycling stability of the MnMoO4@g-C3N4/CNT electrode. These results signify that the MnMoO4@g-C3N4/CNT is a promising electrode material, possessing a pseudocapacitive behavior and remarkable desalination ability, which can be a potential new candidate for the HCDI system.

A new synthesis of O/N-doped porous carbon material for supercapacitors

In this work, a novel carbonization method using H2SO4 as dehydrating agent to prepare graphitized carbon material with O doping is firstly reported. Starch is used as the carbon source. After dehydration in H2SO4 at 100 °C for 6 h, an O-enriched carbon material (OSC) is prepared. It exhibits a specific capacitance of 354 F g−1 at the current density of 1 A g−1 in 1 M H2SO4 solution. After 20,000 cycles, the capacitance retention remains at 110.2 %. It is proved that appropriate amounts of doping O can provide a certain pseudocapacitance, and also improve the wettability of the material, which therefore improve the electrochemical performance of the carbon material. Further, a vapor deposition method using dicyandiamide is applied to grow N-doped carbon nanotubes on the smooth surface of the OSC, which form a three-dimensional conductive network structure on the surface and get a suitable porous structure with the specific surface area of 355 m2/g (NOSC). The specific capacitance of the NOSC is 759 F g−1 at the current density of 1 A g−1 in 1 M H2SO4 solution. After 10,000 cycles, the capacitance retention still remains at 95.8 %. The assembled all-solid symmetric supercapacitor based on the NOSC can be operated in a 0–1.8 V voltage window. The energy density is 41.12 Wh kg−1 with a power density of 449.95 W kg−1.

TiO2-Coated Silicon Nanoparticle Core-Shell Structure for High-Capacity Lithium-Ion Battery Anode Materials

Silicon-based anode materials are considered one of the highly promising anode materials due to their high theoretical energy density; however, problems such as volume effects and solid electrolyte interface film (SEI) instability limit the practical applications. Herein, silicon nanoparticles (SiNPs) are used as the nucleus and anatase titanium dioxide (TiO2) is used as the buffer layer to form a core-shell structure to adapt to the volume change of the silicon-based material and improve the overall interfacial stability of the electrode. In addition, silver nanowires (AgNWs) doping makes it possible to form a conductive network structure to improve the conductivity of the material. We used the core-shell structure SiNPs@TiO2/AgNWs composite as an anode material for high-efficiency Li-ion batteries. Compared with the pure SiNPs electrode, the SiNPs@TiO2/AgNWs electrode exhibits excellent electrochemical performance with a first discharge specific capacity of 3524.2 mAh·g-1 at a current density of 400 mA·g-1, which provides a new idea for the preparation of silicon-based anode materials for high-performance lithium-ion batteries.

Dual conductive surface engineering of LiNi0.8Co0.1Mn0.1O2 cathode for high-energy density

Ni-rich cathode materials have been considered as next-generation power lithium batteries due to their high energy density. However, some of the inherent properties have hindered Ni-rich cathode materials from further applications. Herein, a light weight and self-standing GPI-NCM811 electrode was obtained by filling polyvinylidene fluoride (PVDF) and acetylene black-coated LiNi0.8Co0.1Mn0.1O2 (NCM811) material into graphitized polyimide (GPI) with double conductive surface engineering, which can maintain the structural stability during cycling and ensure the rapid diffusion of electron/Li-ion. The initial specific capacity of GPI-NCM811electrode (210 mAh/g) is obviously higher than the NCM811 electrode (202 mAh/g) at 0.1C. The initial Coulombic efficiency (ICE) of GPI-NCM811electrode increased from 88.9 to 95.9% and its rate capacity is 127 mAh/g at 10 C, which is much higher than that of NCM811 electrode (104 mAh/g). It is because GPI has conductive network structure that can accommodate more electrolyte and fast electron conduction. The GPI-NCM811 electrode capacity remains 83.5% of initial specific capacity between 2.8–4.3 V at 1C after 500 times, while that of NCM811 electrode remains 61.8%. This is due to the synergistic effect of the mixed coating to inhibit the occurrence of side reactions and self-standing to reduce the shedding of electrode material from the fluid collector during long cycle.

Controllable Preparation of Ge/Cu Composite Porous Microspheres as High‐Performance Anode Materials for Lithium‐Ion Batteries

Germanium (Ge) has great advantages as a cathode material for lithium‐ion batteries, but its application in the anode of lithium‐ion batteries is limited by its volume expansion and poor electrical conductivity. Currently, nano‐Ge and composite Ge are the main research directions. Using Ge/copper (Cu) alloy as raw material, herein, pulse discharge and chemical etching method are adopted to prepare a kind of Ge/Cu composite porous microsphere (Ge/Cu@PMS). A 3D conductive network structure is obtained to increase the conductivity of Ge and alleviate the volume expansion of lithium‐ion battery during charge and discharge. As an anode material for Li‐ion batteries, Ge/Cu@PMS has a capacity retention rate reaching 590 mAh g−1 after 200 constant current charge–discharge cycles at a current density of 800 mA g−1, with a capacity retention rate of 79.1%. Therefore, Ge/Cu@PMS has great potential application in lithium energy storage‐related technologies due to its excellent energy‐storage performance and ease of preparation.

An electrical microenvironment constructed based on electromagnetic induction stimulates neural differentiation

A NH2-MXene/PLLA nerve conduit with a conductive network structure is constructed by laser additive manufacturing, which can generate electrical signals driven by electromagnetic induction, and the generated electrical signals can promote the differentiation of nerve cells.

3D C-Co-N-anchored MWCNTs derived from metal-organic frameworks as high-performance electrochemical sensing platforms for the sensitive detection of adrenaline.

Metal-organic frameworks (MOFs) are composed of metal ions and organic ligands with high specific surface areas, controllable porous structures and abundant metal active sites, showing their extraordinary potential in electrochemical sensors. Here, a 3D conductive network structure (C-Co-N@MWCNTs) is designed by anchoring zeolite imidazole frameworks (ZIF-67) onto multi-walled carbon nanotubes (MWCNTs) and carbonizing them. The C-Co-N@MWCNTs exhibit excellent electron conductivity, a porous structure and considerable electrochemical active sites, which can effectively demonstrate high sensitivity and selectivity in the detection of adrenaline (Ad). The Ad sensor exhibited a low detection limit of 6.7 nmol L-1 (S/N = 3) and a wide linear range of 0.02 μmol L-1-1.0 mmol L-1. The developed sensor also displayed high selectivity, good reproducibility and repeatability. The C-Co-N@MWCNTs electrode was further employed in the detection of Ad in a real sample of human serum, suggesting that it is a promising candidate for electrochemical sensing of Ad.

Multilayer joule heating and electromagnetic interference shielding composite fabric with high interfacial durability

High-performance modern integrated intelligent wearable electronic textiles show excellent joule heating performance, electromagnetic interference shielding (EMI) and fire safety. In this work, cotton fabric as a biomass material is used as the framework. Due to its strong electrostatic interaction and hydrogen bonding, 3‑aminopropyl trethoxy silane (KH550) layer, silver nanowire (AgNW) conductive network and water-based polyurethane (WPU) protective layer are formed on the surface of cotton fiber for fabricating composite fabric (AgNW-10-W). Due to the perfect collaborative conductive network and porous fiber network structure, AgNW-10-W shows excellent EMI shielding effectiveness (53.9 dB, 1.3 mm thickness). Furthermore, the surface temperature of the joule heating composite fabric with AgNW as the conductive raw material can reach over 100 °C at an applied voltage of 2 V. Meantime, the composite fabric also shows good cycling and long-term joule heating performance. In the wear tests, the AgNW-10-W cotton fabric has good bending resistance and salt water resistance. It produces heat evenly on the human body's wrist joint and has a certain wear function. In the combustion performance test, the pHRR of AgNW-10-W cotton fabric was 31.3 % lower than that of pure cotton fabric. The work demonstrates the appeal of high-performance multifunctional electronic textiles for joule heating, electromagnetic shielding, and fire safety applications in AI and emerging wearable electronics.

A carbon-covered silicon material modified by phytic acid with 3D conductive network as anode for lithium-ion batteries

The requirement for silicon-based anode material is growing and has received attentions. Silicon is a promising anode material for lithium-ion batteries due to the high theoretical capacity. However, the high volumetric variability of silicon has led to severe chalking and rapid capacity degradation. To ameliorate these problems, a carbon-covered silicon material with a 3D conductive network structure was prepared employing glucose and phytic acid as carbon sources. When acted as the anode for Lithium-ion batteries, the prepared composite material delivered 1612 mAh/g in the first cycle and approximately 600 mAh/g at 0.1 A/g after 200 cycles. In addition, even at 5 A/g, a high capacity of 503 mAh/g was reached, and when recovered to 0.1 A/g, the capacity of 878 mAh/g was maintained.

Medium-Entropy-Alloy FeCoNi Enables Lithium-Sulfur Batteries with Superb Low-Temperature Performance.

Lithium-sulfur battery suffers from sluggish kinetics at low temperatures, resulting in serious polarization and reduced capacity. Here, this work introduces medium-entropy-alloy FeCoNi as catalysts and carbon nanofibers (CNFs) as hosts. FeCoNi nanoparticles are in suit synthesized in cotton-derived CNFs. FeCoNi with atomic-level mixing of each element can effectively modulate lithium polysulfides (LiPSs), multiple components making them promising to catalyze more LiPSs species. The higher configurational entropy endows FeCoNi@CNFs with extraordinary electrochemical activity, corrosion resistance, and mechanical properties. The fractal structure of CNFs provides a large specific surface area, leaving room for volume expansion and Li2 S accumulation, facilitating electrolyte wetting. The unique 3D conductive network structure can suppress the shuttle effect by physicochemical adsorption of LiPSs. This work systematically evaluates the performance of the obtained Li2 S6 /FeCoNi@CNFs electrode. The initial discharge capacity of Li2 S6 /FeCoNi@CNFs reaches 1670.8 mAh g-1 at 0.1 C under -20°C. After 100 cycles at 0.2 C, the capacity decreases from 1462.3 to 1250.1 mAh g-1 . Notably, even under -40°C at 0.1 C, the initial discharge capacity of Li2 S6 /FeCoNi@CNFs still reaches 1202.8 mAh g-1 . After 100 cycles at 0.2 C, the capacity retention rate is 50%. This work has important implications for the development of low-temperature Li-S batteries.

Lattice Boltzmann simulation of the melting enhancement of composite phase change material with highly conductive additives - Effect of discrete particulate phase and continuous conductive network

The melting process of paraffin-aluminum composite PCM in a 2D enclosure is numerically investigated by means of an enthalpy-based lattice Boltzmann method. The aluminum is deployed in discrete particles with size around 100 μm and the continuous fibrous network in the composite PCM, respectively. The effects of equivalent particle diameter, the volume fraction of aluminum additives as well as the local structural rearrangement are systematically investigated. The results demonstrate that the appending of discrete aluminum particles at a low volume fraction (ϕ ≤ 0.2 in this work) even has a negative effect on the melting process, because of the inhibition of the natural convection. By concentrating the particles in either back and top area, the melting performance could be slightly promoted. However, the improvement is very limited. Instead, it is more effective to utilize the continuous conductive fibrous network structure to accelerate the melting, which is suggested to be bespread over the entire PCM with larger local space in the direction of temperature gradient. Furthermore, it is discovered that the critical melting time reduces exponentially with the increase of fiber volume fraction. This work gives a comprehensive understanding of the differences between the discrete particles and continuous structures in the heat transfer enhancement of composite PCM, and offers an optimization strategy in the fabrication of fiber/foam structures.

Enhancement of electrically conductive network structure in cementitious composites by polymer hybrid-coated multiwalled carbon nanotube

Enhancement of electrically conductive network structure in cementitious composites by polymer hybrid-coated multiwalled carbon nanotube

FDM printed MXene/MnFe2O4/MWCNTs reinforced TPU composites with 3D Voronoi structure for sensor and electromagnetic shielding applications

Wearable sensors with a three-dimensional (3D) structural design and electromagnetic shielding performance are significant for the future development of wearable electronic devices. However, it remains a challenge to achieve the target goals. Herein, the thermoplastic polyurethane (TPU)/Ti3C2Tx (MXene)/MnFe2O4/Multi-walled carbon nanotubes (MWCNTs) (i.e., TMMM) composites were innovatively designed using parametric Voronoi structure with different pore sizes and porosity upon fused deposition molding (FDM) printing. The two-dimensional (2D) MXene/zero-dimensional (0D) MnFe2O4 hybrid fillers were built initially by electrostatic bonding strategy, followed by adding the one-dimensional (1D) MWCNTs as a conductive bridging agent, this way endowed the nanofillers with different dimensions uniformly dispersed to form a superb conductive network structure in the TPU matrix. When applied as pressure sensors, the TMMM composites exhibited adjustable gauge factor (GF = 1.33–3.73), extensive sensing compression range (∼89% strain with 12.03 MPa stress), good durability (6000s cyclic compression), which was very conducive to monitoring human motion, such as finger bending, wrist bending, speech recognition, etc. The sensing mechanisms were also studied using the Finite element simulations, and the variation trend of resistance change was in good agreement with the simulation results. The average electromagnetic interference shielding efficiency (EMI SE) value of the 2.1 mm-thick printed composite reached 31.2 dB, suggesting that 99.9242% of electromagnetic waves can be shielded. The proposed strategy not only provided a solution to reduce the weight of electromagnetic shielding materials, but also provided an efficient method for developing porous 3D printed parts with adjustable sensing properties at the macroscopic scale towards wearable electronic devices.