High-performance nanostructured rGO/MXene films: Synergistic design for high conductivity

Preparation of highly conductive metal doped/substituted Li7P2S8Br(1-x)Ix type lithium superionic conductor for all-solid-state lithium battery applications

The importance of lightweight materials has been growing significantly, not only in the development of next-generation transportation systems such as Urban Air Mobility (UAM) and high-efficiency electric vehicles, but also in the aerospace and robotics industries. In these sectors, conductive materials are essential for power transmission and signal delivery. However, the commonly used copper (Cu) wire, despite its excellent electrical and thermal conductivity, contributes substantial weight due to its high density. Therefore, developing next-generation conductive materials that combine lightweight characteristics with high electrical performance is crucial.Carbon nanotubes (CNTs) are considered among the most promising candidates to replace Cu wires. They exhibit exceptional properties, including high electrical conductivity, excellent tensile strength, high current-carrying capacity, good thermal stability (TCR), and low density, making them ideal for lightweight conductor applications. Nevertheless, when CNTs are assembled into macroscopic fiber structures for practical use, the contact resistance between individual nanotubes significantly increases, resulting in degraded electrical conductivity. This limitation hinders their direct use as Cu wire alternatives. Thus, enhancing the electrical conductivity of CNT fibers remains a critical challenge for their practical application in lightweight conductor systems.Numerous efforts have been made to improve the electrical conductivity of CNT fibers. One widely explored strategy involves coating CNT fibers with highly conductive metals using techniques such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and electrodeposition. In this study, we report a copper (Cu) electrodeposition method designed to achieve both internal infiltration and surface-leveling by precisely tuning the electrolyte additive composition and applied potential. This dual-deposition approach not only enhances electrical conductivity but also improves the mechanical and thermal stability of the fibers.CNT fibers are composed of bundled nanotubes, and their properties strongly depend on the degree of nanotube alignment during the spinning process. While wet-spun CNT fibers with high alignment show superior conductivity, they suffer from high fabrication costs, extended processing time, and poor scalability. In contrast, we employed direct-spun CNT fibers, which are more cost-effective and suitable for continuous production, albeit with drawbacks such as poor alignment, lower initial conductivity, internal voids, and surface roughness.To address these limitations, we applied an additive-assisted Cu electrodeposition technique that enhanced both internal infiltration and surface-leveling. This approach filled internal voids, improving thermal stability under current flow, and reduced diameter variation and recess regions, facilitating processes like wire insulation. As a result, the electrical conductivity of Cu-CNT fibers improved significantly from 2.01 × 10⁴ S/m to 4.36 × 10⁷ S/m, nearly 75% of bulk Cu (5.9 × 10⁷ S/m). Additionally, the specific electrical conductivity increased by 37%, reaching 9,168 S·m²/kg compared to pure Cu (6,696 S·m²/kg), confirming the lightweight advantage. Figure 1 highlights this enhancement, along with comparisons to previous studies. These findings demonstrate that additive-assisted Cu electrodeposition is an effective strategy for improving the electrical and physical properties of CNT fiber-based conductors. This scalable approach offers a promising route for next-generation lightweight conductors suitable for aerospace, electric mobility, and robotics, where both electrical efficiency and weight reduction are critical.Reference Daneshvar, F., et al., Fabrication of Light‐Weight and Highly Conductive Copper–Carbon Nanotube Core–Shell Fibers Through Interface Design. Advanced Materials Interfaces, 2020. 7(19).Joseph, K.M., et al., Lightweight Copper–Carbon Nanotube Core–Shell Composite Fiber for Power Cable Application. C, 2023. 9(2).Zhang, X., et al., Ultrastrong, Stiff, and Lightweight Carbon‐Nanotube Fibers. Advanced Materials, 2007. 19(23): p. 4198-4201Xu, L., et al., Single-Walled Carbon Nanotube/Copper Core-Shell Fibers with a High Specific Electrical Conductivity. ACS Nano, 2023. 17(10): p. 9245-9254Subramaniam, C., et al., One hundred fold increase in current carrying capacity in a carbon nanotube-copper composite. Nat Commun, 2013. 4: p. 2202.Sundaram, R., et al., The importance of carbon nanotube wire density, structural uniformity, and purity for fabricating homogeneous carbon nanotube-copper wire composites by copper electrodeposition. Japanese Journal of Applied Physics, 2018. 57(4).Xu, G., et al., Continuous electrodeposition for lightweight, highly conducting and strong carbon nanotube-copper composite fibers. Nanoscale, 2011. 3(10): p. 4215-9.Bazbouz, M.B., et al., Fabrication of High Specific Electrical Conductivity and High Ampacity Carbon Nanotube/Copper Composite Wires. Advanced Electronic Materials, 2021. 7(4).Chen, H., et al., Ultrastrong Carbon Nanotubes-Copper Core-Shell Wires with Enhanced Electrical and Thermal Conductivities as High-Performance Power Transmission Cables. ACS Appl Mater Interfaces, 2022. 14(50): p. 56253-56267.Zou, J., et al., Ni Nanobuffer Layer Provides Light-Weight CNT/Cu Fibers with Superior Robustness, Conductivity, and Ampacity. ACS Appl Mater Interfaces, 2018. 10(9): p. 8197-8204.Han, B., et al., Fabricating and strengthening the carbon nanotube/copper composite fibers with high strength and high electrical conductivity. Applied Surface Science, 2018. 441: p. 984-992. Figure 1

High thermal conductivity nuclear fuels offer important potential advantages over traditional oxide-based fuels such as higher burnup, reduction in fission gas release, and better overall safety of the reactor system. One interesting approach to high thermal conductivity fuels utilizes high thermal conductivity nonfissile additives to UO2 fuel to lower the fuel operating temperature and thereby take advantage of the highly favorable radiation resistance of UO2 at lower operating temperatures. However, differential swelling between the matrix and high conductivity additive phases during high dose irradiation could lead to internal cracking and poor performance. In the current study, ceria (CeO2) and zirconia (ZrO2) surrogate matrices were used to model UO2 behavior. Al2O3 or SiC in the form of nanoscale powder or platelets, respectively, were used for the high conductivity second phase. The nuclear fuel surrogates were sintered to achieve densities greater than 93% of the ideal values. Scanning electron microscopy (SEM) imaging and X-ray diffraction confirmed the uniform distribution of the second phase and that no intermetallic second phase was formed during sintering. The thermal conductivity of the sintered samples was measured from 50°C to 900°C and revealed an important increase compared to pure CeO2 and ZrO2 pellets. Samples were irradiated with 20 MeV Ni6+ ions at midrange doses ranging from 1 to 15 displacements per atom (dpa) and temperatures from 300°C to 700°C. Post irradiation characterization revealed a good stability of the samples at low to medium doses (1 to 5 dpa) but showed a significant microstructural deterioration and decrease of the mechanical properties at 15 dpa. Although microcracking is not observed at the interface between the matrix and high conductivity phase for any investigated irradiation condition, the strength degradation at 15 dpa suggests that these high thermal conductivity fuel forms may not be suitable for high burnup applications in current or proposed fission reactors.

Conductive elastomer composites (CECs) with high elasticity, flexibility and sealability of elastomers and the high electrical conductivity of conductive fillers have been widely used in electromagnetic interference shielding, microwave absorpting, stretchable electronics and sensors. To achieve high electrical conductivity, the commonly used fillers are metal powers, metal-coated inorganic particles and carbon black (CB). High filler content is usually required to effectively improve the conductivity, resulting in low elasticity, low flexibility, and poor processability, all of which limit the applications of CECs. Earlier works reported the synergistic effect of two kinds of fillers with different geometrical dimensions, among which CB and carbon nanotubes (CNTs) are two promising candidate that have been widely studied. However, CNTs are easily entangled and aggregated in elastomer matrix with low viscosity, resulting in unsatisfactory conductivity (mostly 104–105 Ω cm). Moreover, little attention has been paid on CECs with high elasticity, high electrical conductivity stability filled with low filler contents (low cost) for stretchable electronics and strain sensors. The relationship between conductive network and electrical conductivity as well as electrical conductivity stability is still not clear. In this study, we designed and prepared CB/CNTs/polymethylvinylsiloxane (PMVS) composites with good elasticity, high electrical conductivity and good electrical conductivity stability by tailoring the filler network structure of the composites with a low content of CB and CNTs in PMVS matrix. The composite with 1.8 vol% of CNTs and 1.2 vol% of CB showed high elasticity, low volume resistivity (271 Ω cm), and high electrical conductivity stability. CNTs used in this study were carbon nanotube arrays (CNTA) that were in situ synthesized on single-layered double hydroxide (LDH) nanosheets by chemical vapor deposition method. The negatively charged CNTs with a loose structure showed no physical entanglement, which can be well dissociated into many single CNTs and dispersed uniformly in PMVS matrix during mechanical shearing. The high aspect ratio of CNTs can help to obtain high conductivity at low filler content, whereas the isotropy of CB helps to rebuild up the new conductive network after tensile strain. On the other hand, these CNTs are curved in the elastomer matrix, become oriented during stretching, and can curve again after recovery, and thus act as nanosprings. The high elasticity of the CNTs nanosprings leads to high elasticity of the PMVS-CB-CNTs composites. We further studied the relationship between conductive network and electrical conductivity as well as electrical conductivity stability of PMVS-CB-CNTs composites. The results showed that CB and CNTs can form a strong dual conductive network at low filler contents, leading to a high conductivity. When stretching, CNTs act as bridges to connect CB and CB aggregations together, maintaining the strong conductive network and thus high electrical conductivity stability under tensile strain. After tensile recovery, CB and CNTs can reform a strong conductive network, leading to high electrical stability during tensile-release cycles.

Solid-state proton-conductive electrolytes operating at intermediate temperatures (i.e., 100-300 °C) offer numerous advantages for electrochemical devices, for example, faster electrode kinetics. Solid acids (MxHy(AO4)z, where M = Cs, Rb, K, Li, or NH4; A = S, Se, P, or As) have attracted considerable attention as electrolytes for intermediate temperature devices.[1] LiH2PO4 is an interesting material with potential for high conductivity over a wide temperature range. However, high conductivities were reported using a specialized setup, such as a closed system with high water vapor pressure (2 bar at 200 °C),[2] which is difficult for many researchers to access. In this study, we developed a self-standing electrolyte membrane of an H3PO4-containing LiH2PO4 and quartz fiber (QF) matrix, which exhibited a high conductivity (21-28 mS cm−1) over a broad and comparatively low temperature range (100-200 °C) under ambient pressure. A novel polymerization and hydrolysis (PH) treatment was employed to synthesize this membrane.A simple mixture of LiH2PO4 and H3PO4 was used as precursors and heating-induced phosphate polymerization resulted in a unique glassy sol formation that could be reshaped easily (Fig. 1a). X-ray diffraction and Raman spectroscopies revealed that the subsequent regeneration of LiH2PO4 from the phosphate polymer hydrosol upon hydrolysis was responsible for the high ionic conductivity. The infiltrating amount of H3PO4 in the electrolyte was optimized to achieve the maximum conductivity (Fig. 1b). It is also found that the conductivity of LiH2PO4-based electrolytes is sensitive to humidity (Fig. 1c). It is expected that a highly conductive interface forms between the LiH2PO4 particles that contain H3PO4 and H2O, contributing significantly to the electrolyte's high conductivity. Thermogravimetric (TG) analysis further revealed the electrolyte's high hygroscopicity—the ability to absorb water from the atmosphere at temperatures exceeding 100°C. This property may explain its consistent conductivity performance over a wide temperature range.The key factors contributing to the high conductivity of this electrolyte can be summarized as follows: 1) adequate salts embedded in the membrane through PH treatment, 2) the incorporation of extra H3PO4 on LiH2PO4 and 3) humid conditions. The scalability of the PH synthesis process was demonstrated by successfully forming a 100 mm Φ QF sheet with uniform conductivities through the sheet.In summary, this study presents a novel synthesis method for the LiH2PO4-based solid acid electrolyte and offers valuable insights into its proton conduction mechanism. Reference: [1] S. M. Haile et al., Nature, 2001, 410, 910.[2] R. W. Berg et al., Ionics, 2021, 27, 703. Figure 1

ABSTRACTIn the field of the developments of next‐generation polymer electrolyte membranes, high conductivity is often regarded as the first important performance requirement. There is still a huge challenge to face, which is hard to achieve the balance between high ion conductivity (mainly related to ion‐exchange capacity [IEC]) and good mechanical‐dimensional stability (represented by swelling ratio [SR]). Here, a family of crosslinked block polyelectrolytes consisting of hydrophobic rigid poly(arylene ether sulfone) segments to ensure enough dimensional stability and hydrophilic poly(phenylene oxide) segments bearing long‐flexible chains with high‐density multications to serve as crosslinker and carrier for ion transport are prepared. The polyelectrolyte with an IEC of 3.04 mmol g−1 exhibits a high hydroxide conductivity of 126 mS cm−1 and a low SR of 8.6% at 80 °C. No obvious degradation below 200 °C is observed, and maximum tensile strength reaches 28.4 MPa. As a conclusion, these crosslinked membranes based on well‐designed block polyelectrolytes exhibit an excellent combination of high ion conductivity and good mechanical‐dimensional stability to meet the performance requirements for the application of anion‐exchange membranes. © 2020 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 391–401

It has been a challenge to obtain high electrical conductivity in inorganic printed thermoelectric (TE) films due to their high interfacial resistance. In this work, we report a facile synthesis process of Cu–Se-based printable ink for screen printing. A highly conducting TE β-Cu2−δSe phase forms in the screen-printed Cu–Se-based film through ≤10 ms sintering using photonic-curing technology, minimizing the interfacial resistance. This enables overcoming the major challenges associated with printed thermoelectrics: (a) to obtain the desired phase, (b) to attain high electrical conductivity, and (c) to obtain flexibility. Furthermore, the photonic-curing process reduces the synthesis time of the TE β-Cu2−δSe film from several days to a few milliseconds. The sintered film exhibits a remarkably high electrical conductivity of ∼3710 S cm–1 with a TE power factor of ∼100 μW m–1 K–2. The fast processing and high conductivity of the film could also be potentially useful for different printed electronics applications.

Conducting organic materials, such as doped organic polymers1, molecular conductors2,3 and emerging coordination polymers4, underpin technologies ranging from displays to flexible electronics5. Realizing high electrical conductivity in traditionally insulating organic materials necessitates tuning their electronic structure through chemical doping6. Furthermore, even organic materials that are intrinsically conductive, such as single-component molecular conductors7,8, require crystallinity for metallic behaviour. However, conducting polymers are often amorphous to aid durability and processability9. Using molecular design to produce high conductivity in undoped amorphous materials would enable tunable and robust conductivity in many applications10, but there are no intrinsically conducting organic materials that maintain high conductivity when disordered. Here we report an amorphous coordination polymer, Ni tetrathiafulvalene tetrathiolate, which displays markedly high electronic conductivity (up to 1,200 S cm-1) and intrinsic glassy-metallic behaviour. Theory shows that these properties are enabled by molecular overlap that is robust to structural perturbations. This unusual set of features results in high conductivity that is stable to humid air for weeks, pH 0-14 and temperatures up to 140 °C. These findings demonstrate that molecular design can enable metallic conductivity even in heavily disordered materials, raising fundamental questions about how metallic transport can exist without periodic structure and indicating exciting new applications for these materials.

The high conductivity of nanoprous carbons has a significant effect on adsorption of polar molecules; however, the mechanisms underlying this effect are not well-understood, and this effect is generally not considered in adsorption modeling. To investigate the impact of high host conductivity on the adsorption properties of vertical stacks of the graphene sheet, phenol vapor has been chosen as a simple polar adsorptive for our case studies. The influence of high surface conductivity of graphene is taken into account during Grand Canonical Monte Carlo (GCMC) simulations by considering the resulting image charges, and using the corresponding analytical solution to compute the electrostatic energy of the polar molecules confined between two infinite parallel conducting planes. We find that the consideration of the high conductivity affects the atomic configuration of the adsorbed molecules, based on our results for two different pore widths of 1 nm and 0.65 nm. Allowing for the high conductivity results in more stable energy levels, greater heat of adsorption and smaller distances between phenol molecules and the graphene sheet. There results are shown to be in accord with electronic density functional theory calculations, and literature experimental data. The contributions of different guest–guest (phenol–phenol) and guest-host (phenol and graphene) interactions between molecules are studied.

Together with high conductivity, high flexibility is an important property required for next generation organic electronic components. Both properties are difficult to achieve together especially when the components are crystalline because of the intrinsic high brittleness of organic molecular crystals. We report an organic radical crystal system that has both high flexibility and high conductivity. The crystal consists of 9,10-bis(phenylethynyl)anthracene radical cation (BPEA.+ ) units, and shows flexibility under pressure with high conductivity in ambient condition exhibiting average conductivity of 2.68 S cm-1 when normal linear shape, as well as 2.43 S cm-1 when bent. The structural analysis reveals that both a short π-π distance (3.290 Å) between BPEA.+ units that are aligned along the crystal length direction, and the presence of PF6 - counter ions induce flexibility and high electrical conductivity.

This paper applies constructal design to obtain numerically the configuration that facilitates the access of the heat that flows through Y-shaped pathways of a high-conductivity material embedded within a square-shaped heat-generating medium of low-conductivity to cooling this finite-size volume. The objective is to minimize the maximal excess of temperature of the whole system, i.e., the hot spots, independent of where they are located. The total volume and the volume of the material of high thermal conductivity are fixed. Results show that there is no universal optimal geometry for the Y-shaped pathways for every value of high conductivity investigated here. For small values of high thermal conductivity material the best shape presented a well defined format of Y. However, for larger values of high thermal conductivity the best geometry tends to a V-shaped (i.e., the length of stem is suppressed and the bifurcated branches penetrates deeply the heat-generating body towards the superior corners). A comparison between the Y-shaped pathway configuration with a simpler I-shaped blade and with X-shaped configuration was also performed. For constant values of area fraction occupied with a high-conductivity material and the ratio between the high thermal conductivity material and low conductivity of the heat-generating body (φ = 0.1 and = 100) the Y-shaped pathways performed 46% and 13% better when compared to I-shaped and X-shaped pathway configuration, respectively. The best thermal performance is obtained when the highest temperatures (hot spots) are better distributed in the temperature field, i.e., according to the constructal principle of optimal distribution of imperfections.

Characterization of high thermal conductivity fuel surrogates before and after ion irradiation

Chapter 16 - Highly Oriented Graphite with High Thermal Conductivity

Together with high conductivity, high flexibility is an important property required for next generation organic electronic components. Both properties are difficult to achieve together especially when the components are crystalline because of the intrinsic high brittleness of organic molecular crystals. We report an organic radical crystal system that has both high flexibility and high conductivity. The crystal consists of 9,10‐bis(phenylethynyl)anthracene radical cation (BPEA.+) units, and shows flexibility under pressure with high conductivity in ambient condition exhibiting average conductivity of 2.68 S cm−1 when normal linear shape, as well as 2.43 S cm−1 when bent. The structural analysis reveals that both a short π–π distance (3.290 Å) between BPEA.+ units that are aligned along the crystal length direction, and the presence of PF6− counter ions induce flexibility and high electrical conductivity.

1. Application of non-NMDA (non-N-methyl-D-aspartate) receptor agonists onto outside-out patches of cerebellar granule cells gave two characteristic types of response (in different patches) which we have referred to as 'high conductance' and 'low conductance' responses. At a qualitative level these patches could be readily distinguished by the size of the noise increase accompanying their membrane currents. 2. In high conductance patches both AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid) and kainate gave discrete single-channel conductances (10-30 pS), while in low conductance patches, AMPA produced small discrete events (6-10 pS), and kainate opened channels with conductances too small to be directly resolved. All patches examined contained NMDA receptor channels with characteristic 50 and 40 pS conductance levels. 3. Despite the marked differences in single-channel conductances, kainate dose-response curves constructed for high and low conductance patches had similar EC50 values of approximately 150 microM. 4. Spectral analysis of low conductance kainate responses gave an estimated channel conductance of approximately 1.5 pS. In these same low conductance patches AMPA produced discrete openings with two conductance levels; their mean conductances (and relative proportions) were 6 (87%) and 10 pS (13%). 5. In high conductance patches, glutamate (10-30 microM), AMPA (3-10 microM), and kainate (10-30 microM), each activated non-NMDA channels with three multiple conductance levels. The amplitudes of these conductance levels (approximately 10, 20 and 30 pS) were similar for each of the agonists, and their relative proportions (i.e. areas in the amplitude histograms) were constant for all three agonists. In addition, the relative proportion of levels was constant between patches, and all three levels were invariably present. These observations are all consistent with the idea that the three multiple conductances originate from a single receptor channel, activated by AMPA, kainate and glutamate. 6. Non-NMDA single-channel current-voltage (I-V) plots showed outward rectification in high conductance patches. For all three multiple conductance levels the ratio of outward to inward single-channel slope conductance was 1.8 +/- 0.1 and this rectification remained present in symmetrical Na+ solutions. 7. In high conductance patches, the events produced by a rapid application of 20-50 microM glutamate were compared with those activated during steady-state application.(ABSTRACT TRUNCATED AT 400 WORDS)