Pitch-based Carbon Research Articles

Preparation of pitch-based carbon materials by pyrolysis and their electrocatalytic activity in oxygen reduction reaction

Electrocatalytic in-situ production of hydrogen peroxide (H2O2) has attracted continuous attention due to its advantages of cleanliness and safety. However, this method is difficult to meet the requirements of high activity and excellent reusability, which limits its wide application. In this work, cheap pitch was used as carbon source and Co(NO3)2 was used as catalyst precursor to convert its products into carbon nanotubes (CNTs) with high aspect ratio through catalytic pyrolysis. Subsequently, anthraquinone was used to covalently modify CNTs as electrocatalytic electrodes. The experimental results showed that CNTs covalently modified by anthraquinone significantly increased the activity of H2O2 production. The results showed that the improved activity of the optimal electrode was due to the increase of the initial potential of oxygen reduction and the ultimate current density.

Ablation behaviour of Csf/ZrB2-SiC composites fabricated by direct ink writing and reactive melt infiltration

Pitch-based short carbon fibres reinforced Csf/ZrB2-SiC composites were fabricated by direct ink writing of short carbon fibres, followed by slurry impregnation and reactive melt infiltration. Ablation behaviour of the Csf/ZrB2-SiC composite was studied by air plasma test. It is indicated that the skeleton of the oriented short carbon fibres provides heat diffusion channels. Consequently, temperatures at the ablation surface are as low as ∼1730 oC and ∼2000 oC respectively at 4 MW/m2 and 5 MW/m2. The composite presents outstanding ablation-resistant performance with a linear recession rate of ∼ − 0.04 µm/s and mass recession rate of ∼ − 3.40 mg/s at 4 MW/m2, ∼ − 0.17 µm/s and ∼ 3.58 mg/s at 5 MW/m2. It is revealed that the fibres area and matrix area of the composite present different ablation mechanisms. The fibres area is ablated severely, while the matrix area presents excellent ablation-resistance with continuous ZrO2-SiO2 protective layer.

Mesophase pitch derived carbon foams with high compressive strengths and thermal conductivities as cobalt support

Mesophase pitch-based carbon foams are important materials used to store energy and to control heat because of their attractive compressive strength and thermal conductivity properties. Herein, we present work on the improved compressive strength and thermal conductivity of carbon foams using mesophase pitch as the raw material. The FT-IR, TGA, XRD, BET, Raman spectroscopy, Anton Paar 5000 and SEM-EDS were used to provide the insights into the chemical and structural properties of the foams. The TGA has shown that the synthesized carbon foams are stable at high temperatures of 550 °C. The increase in temperature and pressure increases thermal conductivities and compressive strengths from (38–50 W/mK, 3.92–5.01 MPa) and (28–40 W/mK, 1.93–5.51 MPa) respectively. The opposite trend was observed for variation of pressure release time, as pressure release time increases, thermal conductivities and compressive strength decrease from 35 to 25 W/mK, 4.86–1.79 MPa. The H2-TPR has shown that cobalt is reducible on carbon foam which means its application can be extended to other fields. The ICP-OES and AAS confirmed that cobalt was loaded on carbon foam with 14.8 % and 14.5 % respectively. Carbon foams surface area needs to be tuned for further application in catalysis by applying heat treatments to open pores and increase surface area.

One stone two birds: Pitch assisted microcrystalline regulation and defect engineering in coal-based carbon anodes for sodium-ion batteries

Coal-based carbons with abundant resources and low cost are regarded as promising anode materials for sodium‐ion batteries (SIBs). However, their ordered carbon microstructure and abundant surface defects often result in low Na-storage capacity and poor initial coulombic efficiency (ICE). Herein, we propose a simple vapor deposition strategy to synthesize coal-based carbons coated with pitch-based soft carbon layer (PCLC) for potential use as anodes for SIBs. The deposition of pitch-based volatile species allows for an efficient cross-linking reaction between hydroxyl‑containing volatile species and oxygen-rich functional groups of coal, thus generating a disordered inner-phase microcrystalline structure with dominant pseudo-graphitic phase in coal-derived carbon. Meanwhile, the exterior soft carbon coating layer substantially reduces surface defects and increases the electrical conductivity of coal-based carbon. Unlike the pristine lignite coal pyrolytic carbon which exhibited a Na-storage capacity of 290.2 mAh g−1 and ICE of 59.9%, the optimal PCLC (PCLC-1) delivered a higher reversible capacity of 312.2 mAh g−1 and a much-improved ICE of 85.3%. In addition, the PCLC-1 electrode also demonstrated excellent cycle stability with 93.4% retention after 1,000 cycles. When coupled with O3-NaNi1/3Fe1/3Mn1/3O2 cathode, PCLC-1 as an anode in a full cell configuration achieved a high energy density of 220.9 Wh kg−1 with excellent cycling and rate performance. The proposed work offers a unique insight into modulating the microcrystalline structure and surface chemistry of high-performance coal-based carbon anode materials for commercial SIBs.

Improving the interlaminar bonding and thermal conductivity of polymer composites by using split-radial mesophase pitch-based carbon fiber as reinforcement

Mesophase-pitch-based carbon fiber (MPCF) reinforced polymer (MPCFRP) have excellent properties such as high thermal conductivity and high modulus, but the significant anisotropy and surface inertness of MPCF result in the poor interlaminar thermal conductivity and interface bonding of MPCFRP, which greatly limits its application. To address this issue, MPCF-A with split-radial structure was prepared through fiber structure modulation. Compared with the conventional skin-core fiber (MPCF-B), the higher surface roughness and chemical activity of MPCF-A contribute to stronger mechanical locking and chemical bonding between fibers and resin, meanwhile open wedge crack and better graphite microcrystalline structure of MPCF-A play a positive role in increasing the contact points and reducing the phonon scattering in the heat transfer. Therefore, the interlaminar shear strength (40.7 MPa) and interlaminar thermal conductivity (2.09 W/(m·K)) of MPCFRP-A are 9.12% and 27.4% higher than those of MPCFRP-B, respectively, on the basis of the excellent in-plane thermal conductivity (322.8 W/(m·K)). This study provides a reliable guide to improve the interlayer performance of MPCFRP by tailoring the fiber microstructure.

High-performance aqueous zinc ion hybrid capacitors obtained by Na2SO4 additive and dense pore structure.

In this study, the electrochemical performance of zinc ion hybrid capacitors (ZICs) was improved by employing carbon-based materials and electrolyte together. First, we prepared pitch-based porous carbon HC-800 as the electrode material, which possessed a large specific surface area (3607 m2 g-1) and a dense pore structure. This provided abundant adsorption sites for zinc ions, and thus stored more charges. Subsequently, 0.5 M Na2SO4 was added to 1 M Zn(CF3SO3)2 electrolyte via the cationic additive strategy, and the adsorption energy of sodium and zinc ions on the zinc electrode was calculated. The results showed that sodium ions would preferentially be adsorbed on the surface of the zinc electrode, which would inhibit the growth of zinc dendrites, and thus prolong the service life of the zinc electrode. Finally, the presence of solvated zinc ions in the narrowly distributed pores of HC-800 was studied, and the results showed that Zn(H2O)62+ underwent a desolvation process, resulting in the removal of two water molecules to form a tetrahedral structure of Zn(H2O)42+, which made the central surface of the zinc ions closer to the surface of HC-800, and thus the more capacitance achieved. Furthermore, the uniform distribution of Zn(H2O)42+ in the dense and neat pores of HC-800, improved the space charge density. Consequently, the assembled ZIC exhibited a high capacity (242.25 mA h g-1 at 0.5 A g-1) and ultra-long cycle stability (capacity retention at 87% after 110 000 charge/discharge cycles at a high current density of 50 A g-1 and a coulombic efficiency of 100%) and an energy density of 186.1 W h kg-1 and power density of 41 004 W kg-1.

Research progress in the preparation of mesophase pitch from fluid catalytic cracking slurry.

For the preparation of high-performance pitch-based carbon fibers and other carbon materials, mesophase pitch serves as a high-quality precursor. Since FCC (Fluid Catalytic Cracking) oil slurry is abundant in aromatic hydrocarbons and saturated hydrocarbons (about 95% in total), it has become an ideal choice for developing new carbon material products. This paper details the research progress of preparing mesophase asphalt with FCC oil slurry as a raw material from perspectives including the preparation method of synthesizing mesophase asphalt from FCC oil slurry, the impact factors of the formation process of mesophase asphalt and the industrial application of mesophase asphalt.

Mechanism and application of halogenation–dehalogenation in the development of pitch-based carbon fiber: A review

Pitch-based carbon fiber, as one of the important engineering materials, has been widely used in aerospace, defense, sports, and other fields. In the long production process of pitch-based carbon fiber, the property of pitch precursor is significant for the mechanical performance of obtained carbon fiber. Thus, it is crucial to improve the property of pitch precursor by efficient means. Halogenation–dehalogenation is a newly developed method for the controllable synthesis of a pitch precursor from the molecular dimension, including fluorination–defluorination, chlorination–dechlorination, and bromination–debromination. This work reviewed the mechanism and application, as well as the advantages and disadvantages of each halogenation–dehalogenation method.

Fractal structure change of pitch-based carbon fiber during high-temperature heat treatment

High-temperature treatment (HTT) is a vital process to change the structure and improve the performance of pitch-based carbon fiber. The complexity of pore structure and their change during heating can be described by a mathematical concept of fractal. This short contribution reports an in-situ synchrotron radiation small angle X-ray scattering (SAXS) study on the fractal structure change of a kind of pitch-based carbon fiber during heating from 1200 °C to 1700 °C with Joule effect in a small furnace. The change of the fractal structure at different azimuth angles with temperature is revealed, and the corresponding mechanism is analyzed.

Emerging dual carbon fiber batteries

Dual graphite battery emerges as a promising renewable energy storage system with merits of a high working voltage, low cost and environment-friendliness. However, energy density is limited because of a low packing density of graphite. We propose for the first time dual carbon fiber batteries (DCFBs) in which carbon fiber functions as both cathode and anode. With a graphite mass loading of ∼30 mg cm−2 at pitch-based carbon fiber (PCF) cloth, the reversible discharge capacity of PCF-PCF type DCFBs (with PCF cloth cathodes/anodes) can reach 72 mAh g−1 at 0.1 C (1 C corresponding to 80 mAh g−1), resulting in an unprecedentedly high areal capacity of ∼2.2 mAh cm−2. Unlike the general applicability of commercialized carbon fiber as DCFBs anode, only PCF out of five kinds of commercialized carbon fibers can function as DCFBs cathode. Meanwhile, PCF-PCF type DCFB enables investigation into distinct electrochemical behaviors of Li+/PF6−intercalation/deintercalation in PCF. Morphological difference of PCF brought about by Li+/PF6− ions, as found out by ex-situ X-ray diffraction (XRD) and ex-situ scanning electronic microscopy/energy dispersive spectroscopy (SEM/EDS) characterizations, facilitates comprehensive understanding of electrochemical behavior of graphite. This work lays good foundations for future exploration into a new arena of dual ion batteries.

Oxygen-doped carbon nanofiber nonwovens as an effective interlayer towards accelerating electrochemical kinetics for lithium-sulfur battery

Introduction of hydrophilic groups like oxygen/nitrogen groups is considered as a favorite solution to guarantee the functionality for interlayer in lithium-sulfur battery. However, the contributions of different oxygen containing groups was less studied especially when carbon nanofibers are used as interlayer. Herein, a bifunctional electrospun carbon nanofiber nonwoven (xO-CM) derived from coal tar pitch was prepared, followed by acid impregnation. The species and amount of oxygen groups could be finely regulated by changing the acid oxidation time. When xO-CM was adopted as interlayer, increased lithiophilicity on account of oxygen doping enables a larger flux and a uniform release of lithium ions. Ex-situ EIS analysis revealed that the addition of xO-CM in the cell could accelerate the conversion between polysulfides, especially for the liquid–solid and solid–solid reaction. Besides, the oxygen doping facilitated the nucleation of Li2S. Cells with 30O-CM (acid dipping for 30 min) possessed the best facilitation with relatively low solid electrolyte interface resistance and charge transfer resistance. Even at 2C, the cell achieved an ultralow capacity decay rate of 0.06 %, demonstrating its efficatively anchoring and accelerating effect for polysulfides. This work manifested the effective mechanism of oxygen doping for lithium-sulfur battery by adopting pitch-based carbon nanofibers as carrier.

Effect of Temperature on the Complex Modulus of Mg-Based Unidirectionally Aligned Carbon Fiber Composites.

Composite materials based on magnesium-lithium (MgLi) and magnesium-yttrium (MgY) matrices reinforced with unidirectional carbon fibers were prepared using the gas pressure infiltration method. Two types of carbon fibers were used, high-strength PAN-based T300 fibers and high-modulus pitch-based Granoc fibers. The PAN-based carbon fibers have an internal turbostratic structure composed of crystallites. The pitch-based carbon fibers have a longitudinally aligned graphite crystal structure. The internal carbon fiber structure is crucial in the context of the interfacial reaction with the alloying element. There are various mechanisms of bonding to carbon fibers in the case of magnesium-lithium and magnesium-yttrium alloys. This paper presents the use of the DMA method for the characterization of the role of alloying elements in the quality of interfacial bonding and the influence on the complex modulus at increasingly elevated temperatures (50-250 °C). The complex modulus values of the composites with T300 fibers were in the range of 118-136 GPa. The complex modulus values of the composites with Granoc fibers were in the range of 198-236 GPa. The damping capacity of magnesium-based unidirectionally aligned carbon fiber composites is related to the quality of the interfacial bonding.

Preparation and Adsorption Properties of Graphene-Modified, Pitch-Based Carbon Foam Composites.

In view of the good adsorption properties of graphene and carbon foam, they were combined to achieve the optimal matching of microstructures. Taking mesophase pitch as a raw material, pitch-based carbon foam was prepared by the self-foaming method. Graphene gel was prepared as the second phase to composite with the carbon foam matrix; graphene-modified, pitch-based carbon foam composites were finally obtained. Graphene gel was dispersed in the rich pore structure of carbon foam to improve its agglomeration and the porosity, and the active sites of the composite were further increased; the adsorption properties and mechanical properties of the composites were also significantly improved. The microstructure and morphology of the composites were studied by SEM, XRD and Raman spectroscopy; the compressive property and porosity were also tested. Methylene blue (MB) solution was used to simulate a dye solution for the adsorption test, and the influence of the composite properties and MB solution on the adsorption property was studied. Results showed that the compressive strength of the composite was 13.5 MPa, increased by 53.41%, and the porosity was 58.14%, increased by 24.15%, when compared to raw carbon foam. When the mass of the adsorbent was 150 mg, the initial concentration of the MB solution was 5 mg/L, and the pH value of the MB solution was 11; the graphene-modified carbon foam composites showed the best adsorption effect, with an adsorption rate of 96.3% and an adsorption capacity of 144.45 mg/g. Compared with the raw carbon foam, the adsorption rate and adsorption capacity of the composites were increased by 158.18% and 93.50%, respectively.

Coal tar pitch-based carbon composited Sb2Se3 microrod anode toward superior sodium storage performance

Antimony selenide (Sb2Se3) with low cost and high theoretical capacity has been explored as a potential alternative anode for sodium ion batteries. However, the large volumetric variation and sluggish dynamics of Sb2Se3 lead to unsatisfactory long-term cycling life and inferior rate performance. In order to resolve these issues, we proposed a fabrication of Sb2Se3 coated by N-doped carbon derived from coal tar pitch (CTP) by a facile solvothermal method followed by annealing process. The reasonable content of CTP can accommodate the volume expansion, hinder the pulverization and accelerate the charge transfer of Sb2Se3 upon the cycling process. As a result, the Sb2Se3/CTP6 electrode exhibits superior long cycling property with desodiation/sodiation of 129.2(130.6) mAh g−1 after 400 cycles at high current density of 5 A g−1 and outstanding rate performance. The XPS spectrum tests verify the decomposition of Sb2Se3 during the cycling in the first time and demonstrate the CTP can effectively enhance the structural stability of Sb2Se3. The ex-situ XRD is also utilized to reveal the Na+ storage mechanism and phase transition. This work offers a new modification for enhancing the structural stability of alloy-type anode materials.

Evaluating of the oxidative behaviors of isotropic pitch fractions for optimal the mechanical properties of isotropic pitch-based carbon fibers

Oxidative stabilization plays an extremely important role in maintaining shape and structural integrity and preventing inter-filament fusing of isotropic pitch fibers during the subsequent carbonization. However, the actual chemical processes and mechanism of the stabilization reaction are complex and as yet poorly defined because of the complexity of the isotropic pitch. In the study, an isotropic pitch synthesized through the co-carbonization of aromatic-rich distillate oil and polyethylene glycol was fractioned into seven fractions by n-heptane, toluene, and their mixtures. The chemical structure and oxidative reaction features of each pitch fraction were systematically analyzed and investigated by FT-IR, 13C NMR, TG-DSC, SEM, etc. The results revealed that the light pitch fractions with more and longer alky side chains attached to the aromatic nucleus exhibit higher oxidative reactivity and appear to induce a higher content of oxygen uptake to achieve stabilization as compared with the heavy pitch fractions. The stabilization reactions of the pitch fractions were carried out in multiple stages, which was confirmed by the conversion of oxygen-containing functional groups ketones and aldehydes to anhydrides and esters as oxidation temperature increased from 150 ℃ to 290 ℃. Three commercial isotropic pitches produced from petroleum-based raw material were oxidized under different conditions. The results confirmed that it is feasible to predict and optimize the stabilization process by tailoring the pitch components.

Effect of Curing Age on Pull-Out Response of Carbon, Steel, and Synthetic Fiber Embedded in Cementitious Mortar Matrix

Fiber-matrix interface bonding is an important area of concern in fiber-reinforced composites because it is directly related to the mechanical behavior of composites. In this study, interfacial bond properties of four types of fiber at different curing ages were investigated by analyzing fiber pull-out responses. Special attention was given to the fiber–matrix bonding behavior, including fiber tensile strength, average bond strength, equivalent bond strength, and average pull-out energy. Pull-out tests were conducted at 7, 14, 28, and 56 days of curing. Different failure modes in steel fiber, synthetic macrofiber, polyacrylonitrile (PAN)-based carbon fiber, and pitch-based carbon fiber were investigated. According to the pull-out force versus slip curves, different failure patterns were recorded based on the fiber type. Carbon fibers experienced a sudden drop after reaching the peak load, whereas the load decrease in steel and synthetic fiber was not as abrupt. Results also confirmed that steel fibers exhibited the highest pull-out load and energy absorption capacity followed by lower values for synthetic and carbon fibers. While monofilament of steel fiber was able to absorb 1,050 N·mm, monofilament of synthetic fiber and twisted bundles of carbon fibers could absorb 277 and 55 N·mm, respectively. However, the bond strength of straight carbon fibers was comparable to that of synthetic fiber and still lower than steel fiber. It was also derived from the experimental data that an increase in cement matrix age correlates to an improvement in fiber maximum pull-out load, bond strength, and tensile strength. These parameters were identified and compared in all fiber types.

Structural optimization design of CFRP with ultrahigh in-plane thermal conductivity and mechanical strength

Extreme environments in aerospace require structural materials to have good heat transfer properties. Aiming at ultrahigh in-plane thermal conductivity (TC) and mechanical strength, carbon fiber reinforced plastics (CFRP) laminates were prepared by combining PAN-based (CF) and pitch-based carbon fibers (H-CF) prepregs through hot-pressing method. The 0° tensile strength and modulus of [H-CF6/CF11]T can reach 1400 MPa and 297 GPa, respectively. High interlaminar shear strength (78.58 MPa) and ultrahigh in-plane TC (223 Wm−1K−1) are also obtained. Mechanical properties can be enhanced by heterogeneous structure design due to the decrease of number of weak epoxy/cyanate interfaces. We find that the heterogeneous structure can lead to a higher TC. Finite element simulation results confirm that heterogeneous structure is beneficial to the surface heat transfer under localized surface heating. This circumstance is favorable for the protection of devices from overheating when the CFRP is used as shell of aerospace vehicles.

Electroless copper plating mechanism of mesophase pitch-based carbon fibers by the grafting modification of silane couple agents

Electroless copper plating mechanism of mesophase pitch-based carbon fibers (CFs) by the novel silane couple agents (SCAs) sensitization method was investigated based on the three different functional groups of SCAs (KH550, KH570, KH792). The results showed that relatively stable oligomer films could be formed on the surface of CFs after the sensitization treatment with three kinds of SCAs, which promoted adhesion of CFs with copper plating. Besides, a larger crystalline size, lower resistivity, more uniform and continuous coated copper layers were observed in the copper-plated CFs with KH550 grafting modification (Cu@CF-KH550), in comparison with the copper-coated CFs prepared with KH570 or KH 792 grafting modification (Cu@CF-KH570, Cu@CF-KH792). Moreover, Cu@CF-KH550 had the higher thermal stability than Cu@CF-KH570 and Cu@CF-KH792.

Investigation of mechanical behavior and fracture energy of fiber-reinforced concrete beams and panels

This study quantifies the role of carbon fibers as micro-reinforcement in round panels to prevent and slow the formation of cracks. While carbon fiber-reinforced concrete (CFRC) has drawn considerable attention for use in pavements, the majority of CFRC performance assessment is limited to laboratory-scale samples which do not conform to the predominant failure mechanism, yield-line theory, for concrete pavements. In this study, the effects of carbon fiber content and length on flowability, fiber-matrix bond, and mechanical properties were studied and compared to polypropylene fiber. Analysis of the quadratic polynomial fitted surface plot helped to find the most effective fiber content and length. Composite theory was used to predict the flexural strength, and the result were compared to that of experimental results. The last phase consisted of concrete round panels tested under center-point bending in which the failure mechanism under yield line theory was analyzed. Analysis of Variance (ANOVA) model was finally adopted to compare the calculated modulus of rupture in beams and panels. The results showed beneficial effect of CFRC on pre-crack energy absorption, and their role as crack retarders was justified when the absorbed energy was compared to non-fibrous mixes. The residual flexural strength was also improved in beams and round panels reinforced with carbon fibers. Using the composite theory, the experimental-to-predicted flexural strength ratios in PAN-based carbon fibers were in the range of 1.11–1.34. However, the predicted strengths of mixtures with polypropylene and pitch-based carbon fibers were significantly higher than the experimental values.

Facile synthesis of hybrid pitch-based soft carbon as high-performance silicon/carbon anodes for lithium-ion batteries

Facile synthesis of hybrid pitch-based soft carbon as high-performance silicon/carbon anodes for lithium-ion batteries