Conductive Pathways Research Articles

Enhanced thermoelectric performance with improved mechanical strength in Bi2S3/graphite composites

In spite of possessing high Seebeck coefficient and low thermal conductivity, Bi2S3 suffers from poor electrical conductivity, which makes it challenging to use for application in thermoelectric power generator (TEG). In the present work, we have used graphite (G) to improve the electron transport in Bi2S3 by making a composite. Here, we have obtained ZT∼0.15 at room temperature in n-type Bi2S3, which is much higher than that reported for sulphides at room temperature. The inclusion of graphite in Bi2S3, provides a conductive pathway for the easy transport of electrons, and leads to a surge in electrical conductivity. As a result, a high thermoelectric power factor ∼643 μW/m-K2 is attained, which is 30 times higher than that of pristine Bi2S3 at room temperature. The maximum ZT ∼0.3 is obtained for 1.5 wt% graphite-Bi2S3 composite at 705 K temperature. Furthermore, the mechanical strength of Bi2S3 is found to be significantly improved by graphite inclusion, which offers better load bearing capacity for practical application as TEG.

Combined Effect of Halogenation and SiO2 Addition on the Li-Ion Conductivity of LiBH4

In this work, the combined effects of anion substitution (with Br− and I−) and SiO2 addition on the Li-ion conductivity in LiBH4 have been investigated. Hexagonal solid solutions with different compositions, h-Li(BH4)1−α(X)α (X = Br, I), were prepared by ball milling and fully characterized. The most conductive composition for each system was then mixed with different amounts of SiO2 nanoparticles. If the amount of added complex hydride fully fills the original pore volume of the added silica, in both LiBH4-LiBr/SiO2 and LiBH4-LiI/SiO2 systems, the Li-ion conductivity was further increased compared to the h-Li(BH4)1−α(X)α solid solutions alone. The use of LiBH4-LiX instead of LiBH4 in composites with SiO2 enabled the development of an optimal conductive pathway for the Li ions, since the h-Li(BH4)1−α(X)α possesses a higher conductivity than LiBH4. In fact, the Li conductivity of the silica containing h-Li(BH4)1−α(X)α is higher than the maximum reached in LiBH4-SiO2 alone. Therefore, a synergetic effect of combining halogenation and interface engineering is demonstrated in this work.

Microstructure and electrical property of composite Co-W/CuO multilayered oxide coating for solid oxide fuel cell interconnector

To overcome the challenges related to the electrical resistance owing to the growth of the Cr-containing oxide layer in the SOFC system at high temperature, a composite coating of Co-W/CuO was fabricated on ferritic stainless steel for interconnectors by composite electroplating and pre-oxidation treatment. Compared to the Co-W alloy coating, the addition of CuO led to the formation of Cu-Co spinels and Cu-W composites, which affected the surface microstructure of the coating. Scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM) investigations shows that CuWO4 nano-particles formed in the Cr-rich layer beneath the CoWO4 layer, of which the lattice deviation leads to the formation of oxygen vacancies. The CuWO4 acted as conductive pathways, reducing the electrical resistance. Long-term oxidation exposure further demonstrated that the Co-W/CuO coated SUS 430 exhibited a stable electrical conductivity of 10.23 mΩ cm2.

Substantial improvement of thermal conductivity and mechanical properties of polymer composites by incorporation of boron nitride nanosheets and modulation of thermal curing reaction

AbstractThermal conductive polymer‐based composites synchronously with stable dielectric and excellent mechanical properties are urgently needed for high‐temperature‐resistant electronic devices. Here, a significant improvement in the thermal conductivity (TC), thermal stability, dielectric, and mechanical performance was simultaneously achieved in the polyarylene ether nitrile (PEN)/divinyl siloxane‐bisbenzocyclobutene (BCB) matrix through the incorporation of boron nitride nanosheets (BNNS) combined together with the post‐solid phase chemical reaction technique. The significant increase in the effective filler‐filler and filler‐crystal contacts in the composites was the main reason for the improvement in TC and dielectric constant. Besides, glass transition temperature (Tg) and mechanicals were enhanced in the presence of cross‐linked networks. By synchronously adding 15 vol% BNNS, the TC of composites after treatment reached up to 5.582 W/m.K, enhanced by 4.4 times higher than untreated. The dielectric constant was down to 2.93 at 1 MHz and the loss remained at a relatively low level. Meanwhile, the composite showed significantly enhanced thermal stability, mechanicals, and hydrophobicity (Tg = 336°C, T5% = 529°C, tensile strength and modulus was 94.5 MPa and 5.3 GPa, respectively, the contact angle was 101.76°). Thus, it promotes an effective strategy for fabricating a high‐performance‐polymer composite, which has the potential used in electronic materials.Highlights Crystallization‐crosslinking strategy optimizes overall performance. Crystals fill gaps between BNNS layers and connect thermal conductive pathway. Crosslinked networks limit molecular chain motion to reduce phonon scattering. The highest TC of the PEN/BCB/BNNS composite is up to 7.451 W/m.K. Thermal property shows significant improvement after crosslinking especially Tg.

Oriented Three-Dimensional Skeletons Assembled by Si3N4 Nanowires/AlN Particles as Fillers for Improving Thermal Conductivity of Epoxy Composites.

With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have become of increasing interest. Traditionally, higher filler fractions are required to obtain a high thermal conductivity, but this leads to a decrease in the mechanical properties of the composites and increases the cost. In this study, silicon nitride nanowires (Si3N4NWs) with high aspect ratios were successfully prepared by a modified carbothermal reduction method, which was further combined with AlN particles to prepare the epoxy-based composites. The results showed that the Si3N4NWs were beneficial for constructing a continuous thermal conductive pathway as a connecting bridge. On this basis, an aligned three-dimensional skeleton was constructed by the ice template method, which further favored improving the thermal conductivity of the composites. When the mass fraction of Si3N4NWs added was 1.5 wt% and the mass fraction of AlN was 65 wt%, the composites prepared by ice templates reached a thermal conductivity of 1.64 W·m-1·K-1, which was ~ 720% of the thermal conductivity of the pure EP (0.2 W·m-1·K-1). The enhancement effect of Si3N4NWs and directional filler skeletons on the composite thermal conductivity were further demonstrated through the actual heat transfer process and finite element simulations. Furthermore, the thermal stability and mechanical properties of the composites were also improved by the introduction of Si3N4NWs, suggesting that prepared composites exhibit broad prospects in the field of thermal management.

Glycerol-treated polypropylene/carbon black nanocomposites: Analysis of electrical, rheological, thermal and mechanical properties

Electrically conductive nanocomposites based on polypropylene (PP) were prepared using carbon black (CB) nanoparticles via melt blending in the presence of glycerol and castor oil as hydroxyl functional dispersing aids and maleic anhydride–grafted polypropylene (MAgPP) as a compatibilizer. Initially, electrical conductivity of PP/CB nanocomposites with different dosages of both CB nanoparticles and dispersing aids were investigated through electrical analysis. Results indicated that castor oil had no beneficial effects on electrical conductivity. However, the efficiency of 3 wt% loading of glycerol was verified through measurements of electrical, rheological, thermal and mechanical properties as well as by morphological studies. The volume electrical conductivity value of PP nanocomposites containing 12 wt% CB significantly enhanced to 1.2 × 10−4 S/cm by adding 3 wt% glycerol in compared with nanocomposite without glycerol with the volume conductivity value of 1.8 × 10−6 S/cm. Incorporation of optimum amount of glycerol favoured the dispersion of nanofiller in the matrix which was confirmed by scanning electron microscopy observations, leading to higher conductivity due to better formation of conductive pathways within the matrix. Additionally, at the same concentration of CB nanofiller, samples treated with 3 wt% glycerol showed higher melting temperatures, storage modulus ( Gˊ), complex viscosity, tensile modulus and elongation at break. These findings indicate that adding an optimum amount of an efficient hydroxyl functional component like glycerol into PP/CB nanocomposite can be a promising way to enhance the electrically conductive performance while other properties could be maintained well or even improved.

Rare earth ion-infused α-MnO2 nano-rods for excellent EMI shielding efficiency: Experimental and theoretical insights

In this communication, for the first time rare earth elements like Gd3+ and Er3+ ions are impregnated into the α-MnO2tunneled structure involving the modified chemical synthesis route followed by hydrothermal technique. X-ray diffraction patterns and Raman spectroscopy confirm the proper phase formation without any impurity. A theoretical in-depth DFT study for the electronic bands and variation of density of states with the infusion of rare earth elements into the host structure confirms the experimental findings and depicts the suitability of the material for the EMI shielding application. The novel synthesis technique helps to achieve uniform nanorod formation with a high specific surface area. Doping-induced defects, high surface-to-volume ratio, Maxwell-Wagner–Siller interfacial polarization, etc. lead to achieving high dielectric response with moderate tangent loss at a frequency range of 40 Hz to 1 MHz. Temperature-dependent dielectric behavior indicates the paramagnetic to ferromagnetic transition at 120 °C and 70 °C for the Gd- and Er-doped α-MnO2 samples respectively. The electromagnetic interference (EMI) shielding effectiveness (SE) has achieved a maximum of −43 dB at 15.3 GHz and − 46 dB at 15.3 GHz for Gd- and Er-doped α-MnO2 thin layer of thickness ∼600 μm respectively. Higher dipolar polarization, loss tangent, conductive pathways, and defects inside the crystal lead to attaining a high EMI shielding efficiency. This result reveals >99.997% EMI SE against the hazardous electromagnetic waves in the microwave/GHz frequency region.

A braided construction of ionogels as a wearable sensor for human motion monitoring

A highly stable flexible sensor from the braided organization of linear ionogel (IG-BPS) was reported in this work to monitor the human physiological signals and daily movements. The compression effect in the normal direction arisen from the longitudinal stretching is prone to sensor distortion and energy dissipation. This braid construction can effectively reduce the interference of stretching on the stress sensing accuracy. The piezoresistive variations in the longitude and latitude directions of the braided structure can be mutually compensated during sensor deformation, simultaneously generating ample conductive pathway to attenuate hysteresis behaviors significantly. The IG-BPS features great flexibility with broad pressure applications (0–30kPa), high sensing behavior (S=0.137 kPa−1, GF=0.029) and stability (>1000 cycles), which can be fabricated in a simple but efficient strategy. This sensor is capable to accurately detect normal movement and subtle epidermal pulse waves at various locations of human body (heart beating and pulse bounding), which is crucial for real-time tracking the changes in overall wellness status especially the cardiovascular health went through an intensive exercise process. It is expected that this braided organization sensor would act as an exciting part in sports-level tracking, healthcare assessment as well as human-machine interactions development.

Augmentation of Liquid Metal Particle Mechanics via Non‐Native Oxide Nanoshells

AbstractRoom‐temperature liquid metal particles based on gallium have become significantly important for developing next‐generation soft electronics. Eutectic gallium‐indium (EGaIn) alloys can be fabricated into core‐shell particles discretely encapsulated by a passivating oxide. Application of mechanical stimuli results in rupturing the molten core through the oxide shell, merging EGaIn particles to form conductive pathways. Generally, the mechanical properties of EGaIn are largely defined by the native oxide which imparts viscoelastic properties to the fluid. In this work, the practical implications of EGaIn deformation and fracture behavior with the native oxide and a non‐native inorganic silica shell are demonstrated. To augment the mechanical properties of EGaIn, silica nanoshells are introduced as a chemically inert coating to enable brittle fracture of particles. In situ single‐particle nanoindentation characterization reveals the environmental and geometrical considerations for particle deformation and fracture. Silica‐coated EGaIn particles reach stiffness values at least an order of magnitude higher than that of native EGaIn particles. The thickness of the silica shell can be tailored to further modify the mechanical behavior of EGaIn, enabling potential pressure‐sensitive conductivity. These results provide additional pathways to understand the design and implementation of functionalized EGaIn particles for future applications in mechanoresponsive electronics, plasmonics, and therapeutics.

Metal-grade laminated nanofiber films with outstanding EMI shielding performances and high-temperature resistance

With the growing demands in electronics, communications, and energy, conductive composites face a daunting challenge as criteria for conductivity and mechanical properties rise. Extensive search on nanocomposites and amorphous metals has been motivated by the quest for a conductive material that can enhance strength and deformability. However, finding conductive materials that can overcome the drawbacks of their conventional counterparts and exhibit great strength, toughness and quick charge transmission while accomplishing large-scale production remains a significant challenge. This paper describes an approach to high-temperature flexible conductive materials by utilizing composites composed of aramid nanofiber (ANF) and silver nanoparticles (Ag NPs). The ANF is derived from macro-aramid fibers and retains its excellent mechanical properties and heat resistance. Within the composite, Ag NPs effectively enter the special nanofiber matrix to build a tightly connected conductive pathway on the ANF, thus facilitating efficient charge transport. The resulting Ag-ANF composite films exhibit an impressive electrical conductivity of 36,989.68 S m−1 and a tensile strength of 30.3 MPa. Additionally, they provide outstanding EMI shielding with a value of 107.9 dB. This significant achievement opens up the possibility of metallizing the surface of insulated polymer fibers, thereby enabling effective EMI shielding applications even in challenging and extreme conditions.

The multiple synthesis of layered V2CTx-MXene particles as electrically conductive adhesive fillers in printed electronics

2D V2CTx was modified with Ag+ and rGO and doped into Ag copper-plated powder as a conductive filler to improve the conductivity of the conductive adhesive. The incorporation of 2D V2CTx composites connected the dispersed Ag copper-plated powder to form an effective conductive pathway. And as the content of 2D V2CTx composites increases, the resistivity of the epoxy conductive adhesives (ECAs) first decreases and then changes in an increasing trend. This is mainly because the right amount of 2D V2CTx can be established in conjunction with Ag copper-plated powder to form a conductive network inside the epoxy resin, but the increase in 2D V2CTx composite will accumulate in the epoxy resin, which in turn will impede the transmission of current, the resistivity can reach a minimum of 6.84 × 10-6 Ω·m.

Interlayer spacing control strategy to construct the rapid thermal conductivity channel in the molten salt phase change materials

With the goal of improving the thermal conductivity of inorganic salt PCMs without significantly affecting the thermal energy storage density, a functionalized modification strategy to regulate the layer spacing of nano two-dimensional (2D) materials was proposed to construct a thermal conduction pathway in phase change materials (PCMs). In the instance of graphene, we proposed hydroxylation to increase the lamellar spacing between graphene, improve its dispersion in molten salt PCMs, and speed heat transfer of graphene composite molten salt. When compared to pure graphene, the addition of hydroxylated graphene (GOH) improved the thermal conductivity of PCMs significantly. The thermal conductivity model demonstrated that the thermal conductivity pathway can be constructed by equally dispersing enough GOH to further increase the thermal conductivity. When the GOH percentage was 0.8 %, the composite's thermal conductivity was 2.60 W/(m·K), which was 118.5 % greater than the graphene composite with the same content. When the melting point was 240.00 °C, the composite material had a high latent heat of 355.52 J/g. The morphology characterization and thermal conductivity model analysis show that adjusting the layer spacing can improve graphene dispersion, facilitating the construction of thermal conduction pathway in PCMs, accelerating heat transfer, and essentially maintaining PCMs' original thermal energy storage density. Therefore, the strategy of regulating the layer spacing of 2D materials in this study has the potential to extend the application of other 2D materials used in PCMs to improve the heat storage properties.

3D Highly Stretchable Liquid Metal/Elastomer Composites with Strain‐Enhanced Conductivity

AbstractCurrent stretchable conductors, often composed of elastomeric composites infused with rigid conductive fillers, suffer from limited stretchability and durability, and declined conductivity with stretching. These limitations hinder their potential applications as essential components such as interconnects, sensors, and actuators in stretchable electronics and soft machines. In this context, an innovative elastomeric composite that incorporates a 3D network of liquid metal (LM), offering exceptional stretchability, durability, and conductivity, is introduced. The mechanics model elucidates how the interconnected 3DLM architecture imparts softness and stretchability to the composites, allowing them to withstand tensile strains of up to 500% without rupture. The relatively low surface‐to‐volume ratio of the 3DLM network limits the reforming of the oxide layer during cyclic stretch, thereby contributing to low permanent strain and enhanced durability. Additionally, the 3D architecture facilitates crack blunting and stress delocalization, elevating fracture resistance, while simultaneously establishing continuous conductive pathways that result in high conductivity. Notably, the conductivity of the 3DLM composite increases with strain during substantial stretching, highlighting its strain‐enhanced conductivity. In comparison to other LM‐based composites featuring 0D LM droplets, the 3DLM composite stands out with superior properties.

A rational design of a carbon black percolation network glass fibers for modeling an in situ self-reporting composite

The study proposed in this manuscript is aimed at developing a novel real-time monitoring system using carbon black (CB) as the primary sensing material which is nontoxic, highly sensitive, easily synthesizable, and durable at harsh environments. The percolation network characteristics are studied in order to determine a better approach to the existing prototypal model. Varying percentages of CB such as 5, 10, 15, and 20 wt% were added to a 10 wt% of surfactant solution. The solution is coated on a glass fiber (GF) strand and embedded in GF laminate to form a self-monitoring composite. A novel approach is developed where a pre-programmed setup is used to read out electrical resistance directly. The average resistance is found to be 227, 390, 589, and 842 kΩ for varying percentages of CB. 5wt% CB exhibits a higher gauge factor compared to the remaining proportions. It is characterized by studying the percolation network where many of the conductive pathways seemed to become disconnected on the application of load. The XRD characteristics confirmed the phase change in the material at (100) and (101/111) at 2θ = 24.45o and 2θ = 44.47o. A mathematical model is established using which stress in computed using the electrical resistance values obtained from the data acquisition module. This is used to continuously monitor the in situ behavior of any model subjected to external disturbances by self-reporting the data that is necessary for fault diagnosis.

The synergistic and reinforcement mechanism of SiC nanostructures on the ablation properties of silicone rubber composites

With improvements to the performance of ramjets, the ablation environment in afterburning chambers has become more severe, leading to an urgent demand for high-performance thermal protection materials (TPMs). In this study, the reinforcing effects of silicon carbide (SiC) nanowhiskers and nanopowders on silicone rubber composites and their synergistic effects were investigated. Both SiC nanowhiskers and nanopowders improved the thermal stability of the TPMs. SiC nanowhiskers enhanced the thermal conductivity of the TPMs by forming thermal conductivity pathways. Furthermore, SiC nanofillers can reinforce the ablation resistance of the TPM. The best performance was demonstrated by the TPM formulated with five parts SiC nanowhiskers and five parts SiC nanopowders. The ablation rate was reduced by 72.7% relative to the TPM with a basic formulation, and the back temperature increased by only 27.1%. In this study, the SiC nanofiller improved the ablation resistance of composites by densifying the pore structure and strengthening the skeleton of the char layer. Furthermore, the more compact char layer improved the thermal conductivity of the composites. The increase in the thermal conductivities of the composites and the char layer led to a decrease in the thermal insulation properties of the composites.

CFTR-rich ionocytes mediate chloride absorption across airway epithelia.

The volume and composition of a thin layer of liquid covering the airway surface defend the lung from inhaled pathogens and debris. Airway epithelia secrete Cl- into the airway surface liquid through cystic fibrosis transmembrane conductance regulator (CFTR) channels, thereby increasing the volume of airway surface liquid. The discovery that pulmonary ionocytes contain high levels of CFTR led us to predict that ionocytes drive secretion. However, we found the opposite. Elevating ionocyte abundance increased liquid absorption, whereas reducing ionocyte abundance increased secretion. In contrast to other airway epithelial cells, ionocytes contained barttin/Cl- channels in their basolateral membrane. Disrupting barttin/Cl- channel function impaired liquid absorption, and overexpressing barttin/Cl- channels increased absorption. Together, apical CFTR and basolateral barttin/Cl- channels provide an electrically conductive pathway for Cl- flow through ionocytes, and the transepithelial voltage generated by apical Na+ channels drives absorption. These findings indicate that ionocytes mediate liquid absorption, and secretory cells mediate liquid secretion. Segregating these counteracting activities to distinct cell types enables epithelia to precisely control the airway surface. Moreover, the divergent role of CFTR in ionocytes and secretory cells suggests that cystic fibrosis disrupts both liquid secretion and absorption.

Molecular engineering of N-rich ZIF-integrated graphene composite interface for efficient physiochemical confinement and catalytic conversion of polysulfides in lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are regarded as one of the most promising energy storage systems because of their high theoretical specific capacity, energy density, low cost, and environmental benignancy. However, the practical application of Li–S batteries has been hindered by inevitable polysulfides shuttling behavior, the sluggish redox kinetics, and poor electrical conductivity of sulfur, which lead to rapid capacity decay and low active material utilization. In this study, we report a multifunctional layer consisting of N-rich zeolitic imidazolate frameworks (ZIF)/reduced graphene oxide (rGO) composite (NZG) as an electrocatalyst to overcome the drawbacks of Li–S batteries. During the preparation of NZG, deamination of the ZIF8A induces the incorporation of abundant N-containing moieties into rGO (pyridinic and pyrrolic N), which results in providing favorable active sites for polysulfides confinement and their rapid conversion via physiochemical interactions. Additionally, hierarchical pores with large surface area and interconnected conductive pathways in the as-prepared multifunctional layer accelerate the catalytic conversion kinetics of polysulfide species, leading to high sulfur utilization and enhanced Li–S battery electrochemical performance. This work suggests an efficient approach for designing multifunctional layers to achieve high-performance Li–S batteries.

A highly stretchable and sintering-free liquid metal composite conductor enabled by ferrofluid

Stretchable and highly conductive elastomers with intrinsically deformable liquid metal (LM) fillers exhibit promising potential in soft electronics, wearables, human-machine interfaces, and soft robotics. However, conventional LM-elastomer (LME) conductors require a high loading ratio of LM and the post-sintering to rupture LM particles to achieve electric conductivity, which results in high LM consumption and process complexity. In this work, we presented a straightforward and post-sintering-free method that utilizes magnetic aggregation to fabricate stretchable LME conductors. This was achieved by dispersing LM ferrofluid into the elastomer precursor, followed by applying the magnetic field to induce the aggregation and interconnection of the LM ferrofluid particles to form conductive pathways. This method not only simplifies the preparation of initially conductive LME but also reduces the LM loading ratio. The resulting conductive LME composites show high stretchability (up to 650% strain), high conductance stability, and magnetic responsiveness. The stretchable LME conductors were demonstrated in various applications, including the creation of flexible microcircuits, a magnetically controlled soft switch, and a soft hydrogel actuator for grasping tasks. We believe the stretchable LME conductors may find wide applications in electronic skins, soft sensors, and soft machines.

Preparation of High Conductive Medium and Establishment of Laege Capacity Conductive Channel.

The preparation of highly conductive media and the construction of conducting channels play a crucial role in improving the electrical conductivity of electrically conductive adhesives. Therefore, a new MXene structure is reported in this paper, and the improved structure is rationally designed by computational modeling, which greatly prevents the buildup of MXene nanosheets, improves the stability of the structure, and creates a wide electron transfer channel, and the capacitance contribution of this structure is up to 86.3%. By mixing MXene modified with Ag-plated copper powder in a quantitative relationship to form high conductive media, the electrical conductivity is largely improved and the defect of low electron transfer rate of conventional conductive fillers is broken. The potential value of high conductive media is largely exploited using high throughput and machine learning methods, and here we show that the resistivity has reached 9.668 × 10-7 Ω m. The first principles investigate the conductive channels and electron transfer pathways of high-conductive media at the atomic level, further revealing the mechanism of action of high-conductive media. This study is also the first report on the application of MXene to high-conductive media.

Flexible Paper and Cloth Substrates With Conductive Laser Induced Graphene Traces for Electroanalytical Sensing, Energy Harvesting and Supercapacitor Applications

Flexible technology is the new era of technological innovations in a variety of applications such as sensors and energy harvesting. Development of conductive pathways on malleable materials, in an economic manner, plays a significant role in the field of wearable bioelectronics. In this work, a simple approach to fabricate flexible paper and textile based micro-devices has been discussed. The conductive traces on the substrates were created using an optimized laser ablation technique on the material coated substrate to form laser induced graphene (LIG) both on paper and cloth which as conductivity of 825 S/m and 720 S/m respectively. The proposed procedure is utilized as a conductive platform in developing three important designs each for biological sensing, energy harvesting and energy storage applications. From analysis it can seen that, pLIG had better catalytic performances by delivering high power density of 4.5 μW/cm2, better LOD 1.31 μM and improved areal capacitance 15 mF/cm2 Finally, the challenges and the future prospects for developing these novel wearable devices for numerous applications have been enumerated.