Carbon Fiber Network Research Articles

High thermal and mechanical properties of carbon fiber network reinforced copper matrix composites achieved by configuration design and interface engineering

Constructing three-dimensional (3D) fillers within the matrix represents a highly promising strategy for achieving excellent comprehensive performance. In this study, the possibility of implementing 3D network configuration in carbon fiber/copper (CF/Cu) composites is explored. A novel composite structure was developed through template-electrodeposition and hot-pressing sintering techniques, incorporating a 3D CF network within the Cu matrix. Additionally, tungsten carbide (WC) coating was applied to the CF surface using molten salt method. Research findings indicate that the 3D CF networks establish continuous heat flow channels within the Cu matrix, while the WC coating mitigates the interfacial thermal resistance by improving CF-Cu interface bonding. The 3D-CF(WC)/Cu composite obtained through the synergistic strengthening of configuration design and interface engineering exhibits excellent thermal and mechanical properties. The thermal conductivity (TC), coefficient of thermal expansion (CTE), and bending strength of the 3D-CF(WC)/Cu composite in the in-plane direction are 457.4 ± 9.0 W m−1 K−1, 6.9 ± 0.4 × 10−6 K−1, and 281.9 ± 5.2 MPa, respectively; and in the through-plane direction are 400.8 ± 8.9 W m−1 K−1, 6.1 ± 0.4 × 10−6 K−1, and 263.1 ± 5.6 MPa, respectively. This research provides a novel approach to develop carbon reinforced metal matrix thermal management composites.

Strong adsorption Fe[sbnd]N[sbnd]C catalytic cathode for 50,000 cycles aqueous zinc-iodine batteries

Aqueous zinc-iodine batteries have garnered increasing attention due to their low cost and high safety. However, their practical application is impeded by sluggish iodine redox reaction kinetics and the “shuttle effect” of polyiodides, which result in poor rate performance and limited cycled life. Here, we developed N-doped porous carbon fiber derived from Prussian blue and polyacrylonitrile (PAN) as a self-supporting cathode material for zinc-iodine batteries. The material demonstrates a high iodine adsorption capacity in the electrolyte solution. Density Function Theory (DFT) calculations indicate that the prepared materials demonstrate good catalytic activity. Furthermore, the interconnected carbon fiber network, characterized by high conductivity and a large specific surface area, facilitates rapid electron transport and ion diffusion. Consequently, the zinc-iodine battery demonstrates outstanding rate performance (148mAh g−1 at a high current density of 10 A/g) and a long cycling life of 50,000 cycles, with a capacity retention rate of 72.1 %. Additionally, the battery achieves an impressive calendar life of 8 months and 23 days.

N-doped polyacrylonitrile carbon fiber interlayer for uniform and dendrite free Zn metal battery

The aqueous zinc-ion battery’s (AZBs) inherent safety and inexpensive cost make it an attractive prospect for next-generation energy storage. Nevertheless, AZBs are presently troubled by the formation of Zn dendrites and unwanted side-reactions, which can lead to cycling instability and premature collapse. This study demonstrates the fabrication of an N-doped polyacrylonitrile (PAN) carbon fiber (PCF) network with ionic conductivity using the electrospinning of a PAN solution followed by thermal treatment. Zn plating and stripping behavior can be controlled by using a three-dimensional PCF with a polar functional group as an interlayer covering on the zinc anode. This allows for partially deposited zinc to be accommodated, which ultimately results in zinc dendrite-free deposition on the zinc anode. This phenomenon is initially proven in Zn@PCF symmetric cells, and then it is demonstrated further in Zn@PCF/MnO2 whole cells, where the dendritic Zn anode surfaces become completely smooth and devoid of any features. This results in a charging and discharging cycle that is far longer than one would normally experience. The findings of this study offer a viable path toward the development of dendrite-free AZBs with great performance.

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

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

Synergistic effect of in-situ carbon-coated mixed phase iron oxides and 3d electrode architectures as anodes for high-performance sodium-ion batteries

Due to the high theoretical capacity, iron-oxide-based Fe2O3 (1007 mAh g−1) and Fe3O4 (926 mAh g−1) materials can be a promising conversion-type anode material for Sodium-ion batteries (SIBs). However, the low electronic conductivity (10−14 S cm−1) and 200% volume expansion of iron oxide lead to poor cycle life and capacity retention, limiting its commercial application. In this work, carbon-coated mixed-phase iron oxide C-Fe2O3-Fe3O4 (C-IO) was synthesized by pyrolysis using ferrocene precursor. Subsequently, a 3D carbon fiber (CF) network was introduced to improve the electrochemical performance of the material by resolving the volume expansion and pulverization issues. Both the CF network and Fe3O4 provide an electron transport pathway. The conventional Cu-C-IO electrodes deliver a 2nd cycle capacity of 335 mAh g−1 at 250 mA g−1 and exhibit 61.5% capacity retention after 500 cycles. In contrast, the 3D-CF-based IO electrodes show 2nd cycle capacity of 607 mAh g−1 at 50 mA g−1 with 96.4% capacity retention after 35 cycles and 420 mAh g−1 with ∼85.4% capacity retention after 500 cycles at 250 mA g−1 (w.r.t. CF and C-IO active mass, CF contribute ∼ 27% and C-IO ∼ 73% capacity), making it a potential anode for SIBs.

Influence of Complex Geometries on Damage Tolerance of Porous Carbon Fiber Network

Porous materials exhibit a variety of attractive functional properties for aerospace applications, such as low density and low thermal conductivity. However, they must also be mechanically robust and damage tolerant to fully realize their potential. Currently, it is costly and time-consuming for testing under service conditions, therefore, computational models are a good path forward. Due to the inherent microstructural stochasticity of these structures, however, their behavior is difficult to effectively model without detailed experimental studies for validation and benchmarking. To that end this study investigates the mechanical properties of a porous carbon fiber network and ties together the global macroscopic observations to the local mesoscale behaviors dictated by individual fibers and fiber junctions. Strain localization was observed using digital image correlation (DIC) and tied to features within the macroscopic stress–strain plots. Work to quantify the impact of the addition of complex geometries (e.g., cracks and through-holes) on mechanical reliability was conducted. The defects resulted in distinct macroscale mechanical characteristics and mesoscale deformation behaviors, depending on defect type and loading orientation. These results provide broad experimental data to inform and validate modeling approaches to accurately predict and tailor the reliability of porous parts under service conditions.

Tin-antimony/carbon composite porous fibers: electrospinning synthesis and application in sodium-ion batteries

In this work, tin-antimony/carbon composites porous fibers were successfully synthesized by an electrospinning method combined with two-step heat treatment processes, in which SnCl2 and SbCl3 were used as tin and antimony sources, and polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) were used as binders and pore-forming agents. The as-synthesized tin-antimony/carbon composites were systematically characterized by x-ray Diffraction (XRD), Transmission Electron Microscope (TEM), Scanning Electron Microscope (SEM), Energy-Dispersive Spectrometer (EDS), x-ray Photoelectron Spectroscopy (XPS), and Thermogravimetric Analysis-Differential Scanning Calorimetry (TG-DSC). The results indicate that the composite material consists of one-dimensional nitrogen-doped carbon porous fibers as the main matrix, with a three-dimensional network structure in which Sn, SnO2, and SnSb particles are encapsulated. Furthermore, the tin-antimony/carbon composites porous fibers were utilized as self-supported negative electrode for sodium-ion batteries. The results showed that the SNbM-2 sample electrode calcined at 800 °C demonstrated the best cycling stability and rate capability among all the sample electrodes, with a discharge capacity of 319.5 mAh·g−1 maintained after 100 cycles at a current density of 0.1 A·g−1. The excellent electrochemical performance of the SNbM-2 sample electrode is benefited from its unique porous structure and the carbon fiber network structure encapsulating Sn, SnO2, and SnSb particles, which could effectively shorten the Na+ ion transport distance and mitigate electrode volume expansion.

Local strain quantification of a porous carbon fiber network material

While porous materials’ wide range of attractive functional properties have led to their development for a variety of applications, their intrinsically stochastic microstructures prevent straightforward approaches to predicting their mechanical behavior. This is attributed to the mechanisms that govern the macroscale behavior of these materials operating on multiple microstructure-specific length scales spanning several orders of magnitude. The goal of this work was to experimentally observe these operative deformation mechanisms to better improve the development of mechanism-informed models that more accurately predict the behavior of these materials. In this study compression tests were conducted on a porous carbon fiber network material. The resulting macroscale mechanical properties and mesoscale deformation behavior were tied together through digital image correlation (DIC) strain mapping. It was shown that deformation accumulation occurred via both reversible (fiber bending and sliding) and irreversible (fiber and junction failure) ways. The presence of irreversible deformation is indicated by strain being retained after unloading, with values of up to 0.426 locally and 0.248 globally. Local and macroscopic recovery of up to 0.306 and 0.207 strain respectively showcase the operation of reversible deformation. Furthermore, the calculation of energy loss coefficients increasing from 0.016 to 0.371 illustrates that the deformation occurs via dissipative mechanisms.

Small but mighty: Empowering sodium/potassium‐ion battery performance with S‐doped SnO2 quantum dots embedded in N, S codoped carbon fiber network

AbstractSnO2 has been extensively investigated as an anode material for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) due to its high Na/K storage capacity, high abundance, and low toxicity. However, the sluggish reaction kinetics, low electronic conductivity, and large volume changes during charge and discharge hinder the practical applications of SnO2‐based electrodes for SIBs and PIBs. Engineering rational structures with fast charge/ion transfer and robust stability is important to overcoming these challenges. Herein, S‐doped SnO2 (S–SnO2) quantum dots (QDs) (≈3 nm) encapsulated in an N, S codoped carbon fiber networks (S–SnO2–CFN) are rationally fabricated using a sequential freeze‐drying, calcination, and S‐doping strategy. Experimental analysis and density functional theory calculations reveal that the integration of S–SnO2 QDs with N, S codoped carbon fiber network remarkably decreases the adsorption energies of Na/K atoms in the interlayer of SnO2–CFN, and the S doping can increase the conductivity of SnO2, thereby enhancing the ion transfer kinetics. The synergistic interaction between S–SnO2 QDs and N, S codoped carbon fiber network results in a composite with fast Na+/K+ storage and extraordinary long‐term cyclability. Specifically, the S–SnO2–CFN delivers high rate capacities of 141.0 mAh g−1 at 20 A g−1 in SIBs and 102.8 mAh g−1 at 10 A g−1 in PIBs. Impressively, it delivers ultra‐stable sodium storage up to 10,000 cycles at 5 A g−1 and potassium storage up to 5000 cycles at 2 A g−1. This study provides insights into constructing metal oxide‐based carbon fiber network structures for high‐performance electrochemical energy storage and conversion devices.

Unleashing the Power of Sn2S3 Quantum Dots: Advancing Ultrafast and Ultrastable Sodium/Potassium-Ion Batteries with N, S Co-Doped Carbon Fiber Network.

Tin sulfide (Sn2S3) has been recognized as a potential anode material for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its high theoretical capacities. However, the sluggish ion diffusion kinetics, low conductivity, and severe volume changes during cycling have limited its practical application. In this study, Sn2S3 quantum dots (QDs) (≈1.6nm) homogeneously embedded in an N, S co-doped carbon fiber network (Sn2S3-CFN) are successfully fabricated by sequential freeze-drying, carbonization, and sulfidation strategies. As anode materials, the Sn2S3-CFN delivers high reversible capacities and excellent rate capability (300.0 mAh g-1 at 10 A g-1 and 250.0 mAh g-1 at 20 A g-1 for SIBs; 165.3 mAh g-1 at 5 A g-1 and 100.0 mAh g-1 at 10 A g-1 for PIBs) and superior long-life cycling capability (279.6 mAh g-1 after 10 000 cycles at 5 A g-1 for SIBs; 166.3 mAh g-1 after 5 000 cycles at 2 A g-1 for PIBs). According to experimental analysis and theoretical calculations, the exceptional performance of the Sn2S3-CFN composite can be attributed to the synergistic effect of the conductive carbon fiber network and the Sn2S3 quantum dots, which contribute to the structural stability, reversible electrochemical reactions, and superior electron transportation and ions diffusion.

Interfacial MoO2 nanograins assembled over graphitic carbon nanofibers boosting efficient electrocatalytic reduction of nitrate to ammonia

Electrocatalytic nitrate reduction reaction (NO3-RR) for sustainable carbon-free hydrogen carrier (NH3) production from polluted NO3- sources of industrial wastewater is very promising. Mo-based catalysts are defined as popular electrocatalytic materials, but the rational performance achievement of Mo-based catalysts in the NO3-RR remains limited. In this study, to overcome the NO3-RR activity limitation, the interfacial MoO2 nanograins assembled on the N-functional carbon nanofibers (defined as MoO2/C) were constructed by electrospun and controlled graphitizing process. The comparative catalysts dominated by molybdenum oxides namely MoO2/MoO3 were synthesized by controlled calcination in air atmosphere. The MoO2 nanograins anchored in situ on carbon nanofibres could afford more interfacial active regions and accelerate the electron transfer efficiency of the electrocatalytic process by graphitic carbon fiber network. More importantly, MoO2/C was endowed with more oxygen vacancy sites which can trap the free NO3- ions over the reactive sites to enhance the surface interaction of NO3- with catalytic sites during the reaction process. The experimental results showed that the electrocatalytic nitrate reduction performance of the catalyst MoO2/C obviously outperformed that of MoO2/MoO3 in the light of the atomic activity efficiency with a near 7.5 folds enhancement. The MoO2/C affords the highest NH3 yield of 4838.5 µg h−1 mgcat−1 and Faraday efficiency of 30 % at –0.9 V vs.RHE and was endowed with 50 h of continuous reaction stability, proving the potential in practical electrochemical water treatment involving nitrate contamination.

MOFs-derived Cu/Carbon membrane as bi-functional catalyst: Improving catalytic activity in detection and degradation of PFOA via regulation of reactive Cu species

Developing bi-functional materials to simultaneously detect and degrade persistent pollutant perfluorooctanoic acid (PFOA) is of significant importance for environmental and human health. In this study, a copper-based mimic enzyme colorimetric detecting sensor coupling with solar photo-electro-Fenton degradation (SPEF) system was built based on Cu/carbon nanofiber (CNF-Cu/C) membrane. Self-supporting flexible CNF-Cu/C membrane was successfully prepared by solvothermal method with further secondary seed growth and in-situ thermal reduction. Based on calcination temperature regulation, the obtained CNF-Cu/C membrane derived from MOFs/polyacrylonitrile (HKUST/PAN) membrane was characterized by 3D carbon fiber network dispersed with porous carbon skeleton embedded copper species, which exhibited good dispersibility, cycling stability and excellent electrical conductivity. With excellent peroxidase-like activity, CNF-Cu/C can rapidly detect PFOA based on the inhibition of color reaction of tetramethylbenzidine (TMB) with detection limit of 0.133 μM. Furthermore, CNF-Cu/C also exhibited outstanding optical properties and oxygen redox reaction (ORR) activity, and the removal efficiency of PFOA in Cu-SPEF system reached 98.22 % within 180 min under optimal conditions. Based on the results of free radical quenching experiment, EPR experiment and HPLC-MS experiments, the degradation mechanism and degradation path of PFOA by SPEF system were further speculated.

Highly Flexible, Durable, Thermally Stable Multi-Functional Carbon Fabric Applications for Wearable Electronics

In recent years, wearable heaters have attracted widespread attention for applications in personal heating systems and healthcare management, such as thermotherapy of textiles/clothing. In addition, flexible gas sensors are important components of wearable electronic devices used for human safety and healthcare applications. However, the current low flexibility and poor stability of the materials limit their use. In this paper, among various textile materials, the carbon fabric based high-efficiency flexible heater with its own excellent conductivity, which does not contain additives from the manufacturing state, and a sensor using the same. In order to evaluate the performance of the heater, the heating temperature and power according to the applied voltage were analyzed. Also, the temperature distribution of the carbon fabric was observed using a thermal camera. The highly flexible fabric heater is based on a uniformly interconnected carbon fiber network that efficiently and quickly heats the heater with low input power. In addition, it presents a new carbon fabric gas sensor composed of pure carbon fiber itself without additives. The carbon fabric shows a sensitive response to NO2 (24.4%@5ppm) at room temperature, and with an extreme bending radius of 3mm, it shows excellent mechanical reliability against repeated deformations over 1,000 bending cycles. The carbon fabric sensors are extremely flexible and durable even after bending, providing a stable resistance to the sensor base material. The results could be attractive to development of flexible, room temperature operable fabric based wearable gas sensing platforms.

Al2O3 atomic layer deposition on a porous matrix of carbon fibers (FiberForm) for oxidation resistance

Atomic layer deposition (ALD) was used to coat a porous matrix of carbon fibers known as FiberForm with Al2O3 to improve oxidation resistance. Static trimethylaluminum (TMA) and H2O exposures for Al2O3 ALD were used to obtain the uniform coating of this high porosity material. The carbon surfaces were initially functionalized for Al2O3 ALD by exposure to sequential exposures of nitrogen dioxide and TMA. A gravimetric model was developed to predict the mass gain per cycle under conditions when the ALD reactions reached saturation during each reactant exposure. The uniformity of the Al2O3 ALD coating on FiberForm was confirmed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analysis. The SEM, EDS, and gravimetric models were all consistent with a uniform Al2O3 ALD coating on the porous carbon fiber network when the ALD reactions reached saturation on the entire surface area. In contrast, the profile of the Al2O3 ALD coating on the FiberForm was also characterized using undersaturation conditions when the ALD reactions did not reach saturation throughout the FiberForm sample. Based on comparisons with results from models for ALD in porous substrates, these Al2O3 coverage profiles were consistent with diffusion-limited Al2O3 ALD. Oxidation of the FiberForm and the Al2O3 ALD-coated FiberForm was also investigated by thermogravimetric analysis (TGA). TGA revealed that a 50 nm thick Al2O3 coating deposited using 400 Al2O3 ALD cycles enhanced the oxidation resistance. The Al2O3 ALD coating increased the oxidation onset temperature by ∼200 °C from 500 to 700 °C. The oxidation of the FiberForm removed carbon and left the Al2O3 ALD coating behind as a white “skeleton” that preserved the shape of the original FiberForm sample. The Al2O3 ALD coating also decreased the oxidation rate of the FiberForm by ∼30%. The oxidation rate of the Al2O3 ALD-coated FiberForm samples was constant and independent of the thickness of the Al2O3 ALD coating. This behavior suggested that the oxidation is dependent on the competing O2 diffusion into the FiberForm and CO2 diffusion out of the FiberForm.

High capacity and dendrite-free Zn anode enabled by zincophilic 3D Sn-C nanowire framework

Aqueous zinc-ion batteries, due to their safety and low cost, are considered one of the most promising candidates for aqueous zinc-ion battery. However, the rampant dendrite growth of Zn has severely impacted the cycle life of the battery. Herein, we have designed a zincophilic 3D Sn-modified carbon fiber network (Sn-C) as an artificial interface layer framework on the anode surface. This Sn-C nanonetwork can guide the uniform growth of Zn, reducing notorious dendritic growth, and the interlayer growth pattern accommodates the volumetric expansion caused by the large areal capacity deposition. The assembled symmetric batteries have cycled for over 2000 h at 5 mAh cm−2 and 10 mAh cm−2, and even at large areal capacities of 20 mAh cm−2 and 50 mAh cm−2, the batteries have still cycled for over 300 h.

Hydrophobic Carbon Nitride Nanolayer Enables High-Flux Oil/Water Separation with Photocatalytic Antifouling Ability.

Efficient oil/water separation tackles various issues in occasions of oil leakage and oil discharge, such as environmental pollution, recollection of the oil, and saving the water. Herein, a compact superhydrophobic/superoleophilic graphitic carbon nitride nanolayer coated on carbon fiber networks (CNBA/CF) is designed and synthesized for efficient gravity-driven oil/water separation. The CNBA/CF shows excellent oil absorption and an impressive oil/water filtration separation performance. The flux reaches the state-of-art value of 4.29 × 105 L/m2/h for dichloromethane with separation efficiency up to 99%. Successive oil absorption tests, long-term filtration separation, and harsh conditions experiments confirm the remarkable separation and chemical structure stability of the CNBA/CF filter. Besides, the CNBA/CF demonstrates good photocatalytic antifouling ability thanks to the extended visible light absorption and improved charge separation. This work combines the material surface wettability modulation with a photocatalytic self-cleaning property in the fabrication of efficient oil/water separation materials while overcoming the filter fouling issue.

Microstructure and thermal properties of copper matrix composites reinforced by 3D carbon fiber networks

Three-dimensional (3D) carbon fiber (CF) networks were constructed by electrodeposition using Cu foam as template, and then 3D CF/Cu composites were prepared by hot pressing sintering. Experimental investigations revealed the successful formation of a well-connected 3D CF network embedded within the Cu matrix. The constructed 3D CF networks are conducive to establishing effective heat transfer channels in the composites. The thermal conductivity of the 3D CF/Cu composite with 20 vol% CF in the X–Y plane and Z plane are 418 ± 3 Wm−1K−1 and 415 ± 5 Wm−1K−1, respectively. The thermal conductivity of the composites is significantly enhanced, and the thermal conductivity becomes isotropic. Additionally, the construction of the 3D CF network promotes efficient heat transfer in CF/Cu composites, providing a promising strategy for the development of advanced CF/metal thermal management materials.

Structural engineering of SnS quantum dots embedded in N, S Co-Doped carbon fiber network for ultrafast and ultrastable sodium/potassium-ion storage

Tin sulfides have received significant attention as potential candidates for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to their abundance, high theoretical capacity, and favorable working potential. However, the inherent drawbacks such as slow kinetics, low intrinsic electronic conductivity, and significant volume change during cycling, have not been adequately addressed. In this study, we propose a rational and effective approach to simultaneously overcome these challenges by embedding stannous sulfide (SnS) quantum dots (QDs) within a crosslinked nitrogen (N) and sulfur (S) co-doped carbon fiber network (SnS-CFN). The well-dispersed and densely packed SnS QDs, measuring approximately 2 nm, not only minimize the diffusion distance of Na+/K+ ions but also buffer the volume expansion effectively. The N, S co-doped carbon fiber network in SnS-CFN serves as a highly conductive and stable support structure that inhibits SnS QDs aggregation, creates ion/electron transport channels, and alleviates volume variations. Density functional theory (DFT) calculations further confirm that the combination of SnS QDs and the N, S co-doped carbon effectively reduces the adsorbed energies in the interlayer of SnS-CFN. These advantages synergistically contribute to the exceptional sodium/potassium storage performance of the SnS-CFN composite. Consequently, SnS-CFN demonstrates exceptional cyclability, retaining a capacity of 251.5 mAh/g over 10,000 cycles, and exhibits excellent rate capability (299.5 mAh/g at 20 A/g) when employed in SIBs. When used in PIBs, a high capacity of 112.3 mAh/g at 2 A/g after 1000 cycles, a remarkable capacity of 51.4 mAh/g at 5 A/g after 10,000 cycles, and a remarkable rate capability with a specific capacity of 55.5 mAh/g at a high current density of 20 A/g have been achieved.

Co-manipulation of defects and porosity for enhancing the electrical insulation, microwave absorbing/shielding, and thermal properties of filter-paper-derived 2D interlinked carbon fiber networks

To develop light-weight polymer-based multifunctional materials with outstanding electromagnetic wave absorbing/shielding properties and high thermal conductivity, 2D interlinked carbon fiber networks (2D ICFNs) were synthesized via direct pyrolysis of filter papers at 600–900 °C. The pyrolysis temperature (Tp) was controlled to modulate the porosity, defects, and the resulting properties of 2D ICFNs. Owing to the co-manipulation of defects and porosity, the 2D ICFNs formed under Tp = 900 °C exhibit a larger EABWmax/d (3.57 GHz/mm) and stronger absorption (−44.66 dB) at a lower load (15%) compared to most other carbon fiber (CF)-based materials. Their shielding effectiveness is beyond 20 dB over 2.0–18.0 GHz with a maximal value of 76.2 dB at 18 GHz, surpassing the minimum requirement (20 dB) for practical applications. Besides, the 2D ICFNs with moderate porosity and high graphitization bear a larger thermal conductivity (2.69–2.93 W/mK) at a lower filling ratio (20 wt%) in comparison to the majority of previously reported materials. This is primarily due to the shortened phonon/electron transfer paths, decreased phonon-interface/-defect scattering, and continuous paths for thermal transmission in the 2D ICFNs. Overall, it is believed that the 2D ICFNs can be one of the most promising multifunctional fillers for EM absorption applications.

Biomimetic and flexible high-performance carbon paper prepared by welding three-dimensional carbon fiber network with polyphenylene sulfide spherical sites for fuel cell gas diffusion layer

High-performance carbon fiber paper (CFP) is usually an important part of the fuel cell gas diffusion layer (GDL). However, the preparation of CFP for GDL is still a challenge due to its arduous preparation process. Here, inspired by the structure of bird's nest in nature, we present the original design of PPS spherical sites welding three-dimensional (3D) carbon fiber network to produce high-performance CFP by facile wet papermaking and heat treatment. With a 3D CF network as the skeleton and PPS spherical sites as the welding points, CFs/PPS composite paper exhibits good mechanical strength and outstanding flexibility. Meanwhile, the excellent conductivity (6.8 S/cm) is integrated with super-hydrophobic performance, electrothermal performance (Tmax = 365 °C), heat resistance (DTGmax>575 °C), and corrosion resistance, becoming a high-performance multifunctional CFP. The mythical combination of these properties makes CFs/PPS composite paper an ideal candidate in the field of fuel cell GDL. In addition, the evolution of chemical structure of CF/PPS during carbonization is emphasized, which is of great significance for the properties of composite paper. This work presents a leap forward in the preparation of multi-property high-performance CFP in a simple method and is a key step toward exploring how the structural changes of CFs/PPS composite paper can be understood during carbonization.