Ultrahigh Conductivity Research Articles

Expanding the dimensionality of proton conduction enables ultrahigh anhydrous proton conductivity of phosphoric acid-doped covalent-organic frameworks

Expanding the dimensionality of proton conduction enables ultrahigh anhydrous proton conductivity of phosphoric acid-doped covalent-organic frameworks

Proton Conduction Properties of Intrinsically Sulfonated Covalent Organic Framework Composites

The long–term stability of proton conductors is one of the most important factors in evaluating materials. Guest molecules can act as “bridges” for proton conduction channels and reside in the channels of covalent organic frameworks, but they are prone to leakage. Therefore, it is important to develop proton conductors with intrinsic proton conductivity. In this paper, we synthesized an intrinsically sulfonated covalent organic framework, TpPa–SO3H, which has a more stable proton conducting performance than that of TpPa@H2SO4 by loading guest molecules. Meanwhile, the proton conductivity of TpPa–SO3H was further improved by coating a superabsorbent polymer through an in situ reaction to obtain PANa@TpPa–SO3H (PANa: sodium polyacrylate). As a result, the modified composite exhibits an ultrahigh proton conductivity of 2.33 × 10−1 S cm−1 at 80 °C under 95% relative humidity (RH). The stability of PANa@TpPa–SO3H makes it an efficient proton transport platform with excellent proton conductivity and long–term durability.

Size effect enabling additive-free MXene ink with ultrahigh conductivity for screen printing of wireless electronics

Size effect enabling additive-free MXene ink with ultrahigh conductivity for screen printing of wireless electronics

Superprotonic Conductivity in Metal–Organic Frameworks by Charged-Layer-Mediated Proton Conduction

Through a stepwise functionalization strategy, LiCl@UiO-66-F2(SO3H)2 manifests a superprotonic conductivity of 2.86 S cm–1 (at 90% RH and 90 °C), a record breaker so far. Supported by joint experimental–theoretical studies, the ultrahigh conductivity originates from conduction by protons rather than ions and is rationalized to result from the enhanced acidity of −SO3H by introduction of electronegative −F followed by the formation of double charged layers composed of Li+ and −SO3– layers after encapsulation of LiCl. Importantly, the effect of charged layers has been verified, and charged-layer-mediated proton conduction is unprecedentedly proposed to fill in the missing pieces in existing proton conduction mechanisms, giving insight into the rational design of superprotonic conducting framework materials potentially applied as proton exchange membranes in fuel cells.

Metalo Hydrogen-Bonded Organic Frameworks Self-Assembled by Charge-Assisted Synthons for Ultrahigh Proton Conduction

Hydrogen-bonded organic frameworks (HOFs) have been well recognized for constructing solid-state proton-conducting materials due to their inherent well-defined H-bonded networks; however, the design and synthesis of stable HOFs showing ultrahigh superprotonic conductivity is still challenging. Herein, we reported a facile and effective synthetic strategy to build high proton-conducting metalo hydrogen-bonded organic–inorganic frameworks (MHOFs) through charge-assisted inorganic and organic synthons. The supramolecular self-assembly of simple metal salts and tetra-carboxylic acids gives rise to two hydrogen-bonded frameworks, [M(H2O)6][H2tcba] (M = Zn2+, Ni2+; H4tcba = 1,2,4,5-benzenetetracarboxylic acid). X-ray crystallography and gas adsorption confirmed the nonporous nature of the HOIFs. Variable-temperature single-crystal and powder X-ray diffraction experiments reveal the thermal and water stability of the supramolecular structures sustained by exclusively charge-assisted hydrogen bonds. The high density of carboxylic acid groups and coordinated water molecules provide ample protons and hydrophilic environments for efficient proton transport; therefore, variable-temperature and -humidity electrochemical impedance spectroscopy revealed that MHOFs are good supramolecular proton conductors with conductivities up to 1.1 × 10–2 and 2.1 × 10–2 S·cm–1 for 1 and 2, respectively, at 80 °C under 97% RH. Our study demonstrates great potential of charge-assisted inorganic and organic synthons in the design and construction of proton-conducting HOIFs.

Ag Nanoparticle-Thiolated Chitosan Composite Coating Reinforced by Ag-S Covalent Bonds with Excellent Electromagnetic Interference Shielding and Joule Heating Performances.

Conductive composite coatings are an important element in flexible electronics research and are widely used in energy transformation, artificial intelligence, and electronic skins. However, the comparatively low electrical conductivity limits their performance in many specific applications, such as electromagnetic interference (EMI) shielding and Joule heating devices. Therefore, the preparation of ultrahigh-electrical conductivity composite coatings with good flexibility and durability remains a great challenge. Herein, we fabricated multifunctional conductive composite coatings based on thiolated chitosan (TCS) and Ag nanoparticles (AgNPs) by an eco-friendly drop-coating method. The three-dimensional conductive network constructed by thermal sintering imparted the coating with an ultrahigh electrical conductivity of up to 67079.4 S/m. Moreover, the coating reinforced by Ag-S covalent bonding exhibits good stability, including heat resistance, chemical resistance, and mechanical stability. In addition, based on the ultrahigh electrical conductivity, the coating exhibits superior EMI shielding effectiveness and Joule heating capability. With 30 wt % of AgNPs in the coating, the EMI shielding effectiveness of the coating reaches 70.2 dB, far exceeding commercial standards. Additionally, the coating can quickly reach a saturation temperature (Ts) of 195.9 °C at a safe drive voltage of 3 V. These excellent performances demonstrate that the robust and flexible highly conductive composite coatings prepared by this method have attractive potential for EMI shielding and thermal management applications as well as in wearable electronics.

High Sensitivity Surface Defect Inspection of SiC and SmartSiC<sup>TM</sup> Substrates Using a DUV Laser-Based System

SmartSiCTM technology enables the supply of cost-effective and high-quality substrates to support the manufacturing of Silicon Carbide (SiC) Power Devices and the transition to High Volume Manufacturing (HVM) [1]. As detailed in [2] SmartSiCTM is prepared using a poly-crystalline handle wafer, it combines the benefit from both an optimized high quality epi-ready 4H-SiC layer and an ultra high conductivity handle material. Smart CutTM technology can be extended to SiC 200mm substrates and first SmartSiCTM 200mm sample has been prepared [2].SmartSiCTM substrates crystal quality is inherited by donor wafers [1, 2] and do not require a systematic control, enabling a new defects monitoring strategy, focusing on surface defects.This paper describes how a commercially available DUV inspection system was utilized for high sensitivity, high-throughput inspections of 150 and 200 mm 4H-SiC and SmartSiCTM substrates, for the HVM environment. The KLA Surfscan® SP A2 unpatterned wafer inspection system offers the opportunity to complement other inspection technologies to optimize SiC substrate defect control, with low threshold detection, below 150 nm.

High Proton Conductivity of a Bismuth Phosphonate Metal–Organic Framework with Unusual Topology

Despite the interest in proton exchange membrane (PEM) technologies (fuel cells and electrolyzers) for energy applications, the low stability of the electrolyte materials under working conditions (i.e., humidity and temperature) is one of their major limitations. Metal–organic frameworks (MOFs) have recently emerged as promising electrolytes due to their higher stability compared with the currently applied organic polymers, proton conductivity, and outstanding porosity. Here, a novel robust Bi phosphonate MOF (branded as IEF-7) was successfully synthesized and fully characterized, exhibiting an unusual topology due to the irregular coordination geometry of the bismuth cations. Furthermore, IEF-7 exhibited potential porosity, very high chemical and thermal stability, and free −PO3H groups involved in its ultrahigh proton conductivity, reaching 1.39 × 10–2 S cm–1 at 90 °C and 90% relative humidity for, at least, 3 cycles. In order to improve the consolidation and shaping of the powder for testing its ion conductivity properties, a highly MOF-loaded composite (90 wt %) was prepared by adding a proton conductive sulfonated polysulfone binder. The proton conductivity of the resulting composite was in the same order of magnitude as the compacted MOF powder, making this polymeric composite electrolyte very promising for PEM technologies.

Building intercalation structure for high ionic conductivity via aliovalent substitution

Two-dimensional (2D) materials, which possess robust nanochannels, high flux and allow scalable fabrication, provide new platforms for nanofluids. Highly efficient ionic conductivity can facilitate the application of nanofluidic devices for modern energy conversion and ionic sieving. Herein, we propose a novel strategy of building an intercalation crystal structure with negative surface charge and mobile interlamellar ions via aliovalent substitution to boost ionic conductivity. The Li2xM1–xPS3 (M = Cd, Ni, Fe) crystals obtained by the solid-state reaction exhibit distinct capability of water absorption and apparant variation of interlayer spacing (from 0.67 to 1.20 nm). The assembled membranes show the ultrahigh ionic conductivity of 1.20 S/cm for Li0.5Cd0.75PS3 and 1.01 S/cm for Li0.6Ni0.7PS3. This facile strategy may inspire the research in other 2D materials with higher ionic transport performance for nanofluids.

Construction of 1D Heterogeneous Co/C@Ag Nws With Tunable Electromagnetic Wave Absorption And Shielding Performance.

In this study, silver nanowires (Ag NWs) are synthesized at first, and then the 1D heterogeneous Co/C@Ag NWs with a kebab- and popsicle-like microstructures are constructed by in situ growth ZIF-67 on Ag NWs combined with calcination. Results show that the EM wave prevention performance of composites depends on the loading of Co/C particles threaded on the Ag NWs. The popsicle-like structure with high Co/C loading gives Co/C@Ag NWs excellent EM wave absorption performance, which achieved a minimum reflection loss (RLmin ) of -44.5dB with a low filling of 30wt.% in paraffin; while the kebab-like structure with low Co/C loading shows good electromagnetic interference (EMI) shielding effectiveness (SET ) of 30.2dB at the same filler ratio. The enhanced EM wave absorption performance is attributed to the synergy of multiple energy dissipation mechanisms including dielectric loss, magnetic loss, polarization loss, eddy-current loss, multiple reflection loss, as well as proper impedance matching; the good EMI shielding performance is mainly due to the conduction loss brought by the Ag NWs with ultrahigh conductivity. This work provides a reference for the design of electromagnetic wave prevention material with tuned absorption and shielding performance.

Single-Walled Carbon Nanotube/Copper Core-Shell Fibers with a High Specific Electrical Conductivity.

Carbon nanotube (CNT)/Cu core-shell fibers are a promising material for lightweight conductors due to their higher conductivity than pure CNT fibers and lower density than traditional Cu wires. However, the electrical properties of the hybrid fiber have been unsatisfactory, mainly because of the weak CNT-Cu interfacial interaction. Here we report the fabrication of a single-walled CNT (SWCNT)/Cu core-shell fiber that outperforms commercial Cu wires in terms of specific electrical conductivity and current carrying capacity. A dense and uniform Cu shell was coated on the surface of wet-spun SWCNT fibers using a combination of magnetron sputtering and electrochemical deposition. Our SWCNT/Cu core-shell fibers had an ultrahigh specific electrical conductivity of (1.01 ± 0.04) × 104 S m2 kg-1, 56% higher than Cu. Experimental and simulation results show that oxygen-containing functional groups on the surface of a wet-spun SWCNT fiber interact with the sputtered Cu atoms to produce strong bonding. Our hybrid fiber preserved its integrity and conductivity well after more than 5000 bending cycles. Furthermore, the current carrying capacity of the coaxial fiber reached 3.14 × 105 A cm-2, three times that of commercial Cu wires.

Regulating the Electrical and Mechanical Properties of TaS2 Films via van der Waals and Electrostatic Interaction for High Performance Electromagnetic Interference Shielding

HighlightsA flexible freestanding TaS2 film (thickness = 3.1 μm) exhibits an ultralow void ratio of 6.01%, an ultra-high electrical conductivity of 2,666 S cm−1, an electromagnetic interference shielding effectiveness (EMI SE) of 41.8 dB, an absolute EMI SE (SSE/t) of 27,859 dB cm2 g−1, and excellent flexibility withstand 1,000 bends without rupture.The TaS2 composite films exhibit excellent EMI shielding properties and higher tensile strength with better mechanical flexibility, making them suitable for EMI shielding practical applications.

Sewable high-performance poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/layered double hydroxide core-shell fiber electrodes for flexible supercapacitors

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-based fibers are one of the most competitive fiber-type electrodes but still suffer from low electrochemical surface areas (ECSAs) and oversensitivity to humidity for fiber supercapacitor applications. Herein, through rational design, a sewable core-shell fiber electrode of PEDOT:PSS/waterborne polyurethane (WPU) fiber wrapped with nickel/cobalt-layered double hydroxides (NiCo-LDH) has been synthesized via wet-spinning and solution reaction. The fiber core acts as a conductive channel for charge carrier transport. The NiCo-LDH shell possesses unique hybrid architectures of honeycomb-like nanosheet array and hollow nanocages, which provide numerous electrochemical active sites. Simultaneously, the water barrier effect of the NiCo-LDH shell and the interaction between Co2+/Ni2+ and PSS reduce fiber water uptake, thus endowing the fiber with a better geometric stability with low swelling ratio. The as-prepared PEDOT:PSS/LDH fiber has a large ECSA (4060 cm2 g−1) and ultrahigh conductivities no matter in dry (1237.3 S cm−1) or wet (1018.7 S cm−1) state. It also exhibits a high capacitance (188.5 F g−1 at 1 A g−1) and long lifespan (capacitance retention of 94% after 10,000 cycles). The fiber-based supercapacitor shows superb flexibility with stable capacitive behavior under deformation. These characteristics manifest the potential of PEDOT:PSS/LDH fibers for stable high-performance energy storage to support wearable electronics.

MXene/CNTs/Aramid Aerogels for Electromagnetic Interference Shielding and Joule Heating

It is a considerable challenge to develop a composite material with ultra-light and high electromagnetic interference (EMI) shielding efficiency for the next generation of electronic equipment. MXenes have received extensive attention in composite aerogel EMI shielding due to their abundant surface groups and ultra-high conductivity. However, the poor mechanical properties make them difficult to apply on a large scale. Here, we demonstrate a simple method to construct ultra-light conductive Ti3C2Tx MXene/aramid nanofibers (ANFs)/carbon nanotubes (CNTs) aerogels with a “sandwich” structure. CNTs and MXene absorb and reflect electromagnetic waves, while ANF aerogel provides good mechanical strength. Our composite aerogels with an extra-high EMI shielding efficiency of up to 69.0 dB at the X-band, despite their thickness and density being only 2 mm and 0.0428 g/cm3, respectively. At the same time, the composite aerogel with a low 0.0488 W/(m·K) thermal conductivity shows extraordinary flame resistance, heat preservation, and insulation ability. Besides, MXene/ANFs/CNTs aerogel can reach 104 °C in 3 s under an 8 V voltage and shows long-term Joule heating stability. This work provides a forward-looking idea for building multifunctional EMI shielding materials. The obtained aerogels have potential applications in aerospace, portable electronic devices, and defense industries.

A hydrogel electrolyte with ultrahigh ionic conductivity and transference number benefit from Zn2+ “highways” for dendrite-free Zn-MnO2 battery

Aqueous zinc ion batteries (AZIBs) have been regarded as promising energy storage devices owing to high safety and abundant resources. However, it still remains a great challenge to solve the issue of Zn dendrites. So far, some efforts have been made to inhibit dendrites using hydrogels as electrolytes. Nevertheless, it’s more challenging to improve ionic conductivity of hydrogel electrolyte to ensure it’s high enough to provide an environment for rapid transmission of Zn2+. Therefore, new strategies that can simultaneously solve above problems must be explored. Herein, a semi-interpenetrating network P(PEGMEA-AM)/PAM hydrogel electrolyte (s-PPMHE) with molecular chain designability was innovatively constructed. Abundant functional C-O-C groups in linear polymer chain of s-PPMHE can reduce the electrostatic potential of hydrated Zn2+ and release trapped Zn2+, thus significantly accelerating Zn2+ migration with an ultrahigh transference number (tZn2+ = 0.82). Thanks to the unique structural design, s-PPMHE has good mechanical stability and coordination ability with Zn2+, which is conducive to constructing ion migration channels and immobilizing water molecules, thus alleviating water-related parasitic reactions. The theoretical calculation results reveal that s-PPMHE can regulate Zn2+ electric field distribution and boost desolvation kinetics. Therefore, the Zn||s-PPMHE||MnO2 cells exhibit excellent electrochemical performance involving high average coulombic efficiency of 98.9% and ultrahigh specific capacity of ∼ 300 mAh/g at 0.05C (97% of theoretical capacity). Furthermore, s-PPMHE delivers excellent ionic conductivity of 82.65 mS/cm and over 350 h zinc stripping/plating cycling properties. Moreover, the flexible pouch AZIBs based on s-PPMHE show stable voltage under different conditions. This work provides a novel and exploratory strategy for design of hydrogel electrolyte at molecular chain level, and opens up a new avenue to design functional hydrogel matrix for high-performance electrochemical devices.

Highly ion-conductive anion exchange membranes with superior mechanical properties based on polymeric ionic liquid filled functionalized bacterial cellulose for alkaline fuel cells

How to simultaneously improve the ionic conductivity and mechanical properties is a key problem facing currently used anion-exchange membranes (AEMs). Here, biomass-based bacterial cellulose (BC) was used as a porous template to make TiO2 localized mineralization around the surface of BC nanofibers, and constructed a TiO2-coated BC porous substrate (TiO2@BC) with hierarchical structure. Then, the coated TiO2 nanoparticles was densely grafted by quaternary ammonium groups to obtain high ionic conduction ability. After filling with a polymeric ionic liquid (PIL) with high ion exchange capacity through in situ polymerization and crosslinking, the obtained novel PIL-filled AEM possessed ultrahigh ionic conductivity of 100.5 mS cm−1 at 80 °C, which was 72.1% higher than that of the PIL-filled pure BC membrane (only 58.4 mS cm−1). Moreover, by the aid of the synergistic reinforcement effect of TiO2@BC, the membrane exhibited extremely high dry strength of 95.3 MPa and satisfactory wet strength and flexibility. When at fully hydrate state, the membrane with the size of 1 × 4 cm (width × length) can hang a bottle containing 1000 g of water. The single cell equipped with this membrane output the peak power density of 40.2 mW cm−2, showing its great potential as a high-performance biomass-based AEM.

Versatility of Sb-doping enabling argyrodite electrolyte with superior moisture stability and Li metal compatibility towards practical all-solid-state Li metal batteries

Sulfide solid-state electrolytes (SSEs) are considered as one of the most promising candidates for all-solid-state Li metal batteries (ASSLMBs) on account of their high ionic conductivity and outstanding ductility. However, the poor air stability and incompatibility with Li metal seriously obstruct their application in ASSLMBs. Herein, versatile Sb-doped Li6P1−xSbxS5Cl SSEs are successfully developed to tackle these issues. The synthesized Li6P0.925Sb0.075S5Cl displays an ultrahigh ionic conductivity of 3.6 × 10−3 S cm−1 at room temperature by optimizing the concentrations of dopant. Furthermore, such electrolyte exhibits remarkable structural stability and admirable hydrolysis resistance when exposed to humid air or water, owing to the formation of SbS4 units that are thermodynamically stable to water in the Sb-doped electrolyte. Importantly, the Li6P0.925Sb0.075S5Cl SSE can induce the formation of Li-Sb alloy at the Li/SSE interface, which serves critical functions to regulate the Li+ plating/stripping behavior and decrease Li+ diffusion energy barrier across the anode interface, thus endowing an excellent long-term cyclic stability of the Li symmetric batteries (stable cycle at 0.1 mA cm−2 over 800 h) and significantly improved critical current density (1.2 mA cm−2). More encouragingly, either pristine-synthesized or air-exposed Li6P0.925Sb0.075S5Cl enables ASSLMBs with satisfying electrochemical performance at room temperature.

Harmonious state between filled and coated flexible conductive films: An ultra-high conductivity, sensitive and environmentally stable sensing film based on integrated layered structure

There is an urgent need for the development of high-performance and particularly environmentally stable strain sensors to address the requirements of wearable health monitoring for the real environment. However, despite considerable efforts, few classes of conductive elastomers have so far been able to fully satisfy the above requirements. Inspired by the multiple layers of human skin, herein we design an amazing integrated layered structure based on carboxylated styrene butadiene rubber/regenerated sodium lignosulfonate-silver nanowires (XSBR/rSL-AgNWs), including an ultra-high conductivity AgNWs-enriched layer of 500 S/m at loads as low as 5 wt%, an rSL segregated network layer providing a tensile strength 10.2 MPa, and a compact rubber layer with water-resistant property. With such a distinctive integrated layered structure, the film earns an impressive stable conductivity in water with a small amount of filler, a high sensitivity of 110 ms, gauge factor of 145.8 and wide response strain range from 0.5% to 350%. These excellent sensing properties enable the composite film to monitor motion, pulse, and voice signals in complex environments, thus offering a new avenue for the development of flexible electronic devices.

Achieving high-performance Li6.5Sb0.5Ge0.5S5I-based all-solid-state lithium batteries

Sb-based lithium sulfide electrolytes are promising for all-solid-state lithium battery applications due to their ultrahigh Li-ion conductivity (10−2 S/cm) which is even comparable to current liquid electrolytes. However, the poor electrochemical stability between this electrolyte and high voltage layered structure cathode makes it difficult to achieve excellent battery performances. Herein, Li6.5Sb0.5Ge0.5S5I electrolyte with ionic conductivity up to 10 m S/cm is successfully synthesized and the electrochemical failure mechanism of the corresponding battery using bare LiNi0.6Mn0.2Co0.2O2 cathode and Li-In anode is revealed. Furthermore, Li3InCl6 electrolyte is introduced both as an ionic additive in the cathode mixture and as an isolating layer to avoid side reactions. The designed configuration delivers a high discharge capacity of 162.7 mAh/g at 0.5C and sustains 74.5% of the capacity after 200 cycles at room temperature. Moreover, it also can reversibly cycle from -20 to 60 °C with superior battery performances. This work provides a general design strategy for utilizing highly conductive sulfide electrolytes with low stability in all-solid-state batteries.

Direct Writing of Silver Nanowire Patterns with Line Width down to 50 μm and Ultrahigh Conductivity.

Direct writing of one-dimensional nanomaterials with large aspect ratios into customized, highly conductive, and high-resolution patterns is a challenging task. In this work, thin silver nanowires (AgNWs) with a length-to-diameter ratio of 730 are employed as a representative example to demonstrate a potent direct ink writing (DIW) strategy, in which aqueous inks using a natural polymer, sodium alginate, as the thickening agent can be easily patterned with arbitrary geometries and controllable structural features on a variety of planar substrates. With the aid of a quick spray-and-dry postprinting treatment at room temperature, the electrical conductivity and substrate adhesion of the written AgNWs-patterns improve simultaneously. This simple, environment benign, and low-temperature DIW strategy is effective for depositing AgNWs into patterns that are high-resolution (with line width down to 50 μm), highly conductive (up to 1.26 × 105 S/cm), and mechanically robust and have a large alignment order of NWs, regardless of the substrate's hardness, smoothness, and hydrophilicity. Soft electroadhesion grippers utilizing as-manufactured interdigitated AgNWs-electrodes exhibit an increased shear adhesion force of up to 15.5 kPa at a driving voltage of 3 kV, indicating the strategy is very promising for the decentralized and customized manufacturing of soft electrodes for future soft electronics and robotics.