High-temperature Graphitization Research Articles

Boron-doped polyhedral graphite catalyzed by h-BN via structural induction for lithium storage

Artificial graphite is extensively used in power lithium-ion batteries for its exceptional stability and high-rate performance. However, the commercial high-temperature graphitization process is conducted at temperatures up to 3000 °C to enhance the degree of graphitization, resulting in significant electricity consumption and lengthy production cycles. This study aimed to lower graphitization temperatures and shorten times by using h-BN as a catalyst. Employing anthracite coal as the precursor and catalyzing with BN at 2800 °C for just 2 h, we achieved a remarkable graphitization degree of 93.3 %, compared to 83.5 % without BN. This indicates BN's effectiveness in accelerating graphite phase formation. Interestingly, the resultant graphite exhibited polyhedral morphology and incorporated boron doping. As edges increased, lithium-ion diffusion pathways and boron doping enhanced stability within the graphite layers, imparting high rate capability and robust cycle performance. The material delivered reversible specific capacities of 369.6 and 226 mA h g−1 at current densities of 0.1 and 3C, and maintained capacity retentions of 95 % and 92 % after 500 cycles at 0.5C and 1C. These results substantiate the potential for large-scale production of artificial graphite from anthracite coal using BN catalysis and underscore its promise as a superior anode material for lithium-ion batteries.

Large-scale preparation of thermally conductive graphene fiber filaments

Graphene fiber has emerged as a promising carbonaceous fiber with excellent integrated properties. Previous laboratory researches have focused on the prototype single fiber, but the scalable fabrication of graphene fiber filaments still remains nearly unexplored. Here, we report the large-scale industrial fabrication of graphene fiber filaments with high strength and superior thermal conductivity. During scalable wet-spinning process, we introduce step-wise solvent intercalation plastic stretching to improve the uniformity, density and structural order of precursor graphene oxide fiber filaments. The chemical reduction and high-temperature graphitization restore graphene atomic structure and achieve large graphitic crystallite sizes of filaments. The graphene fiber filaments demonstrate favorable overall performances, including tensile strength of 1.4 GPa, density of 1.93 g/cm3, electrical conductivity of 4.1 × 105 S/m, and thermal conductivity of 1204 W/mK. The fabrication of graphene fiber filaments lays a foundation of their wide applications as textiles and composites and the solvent intercalation plastic stretching could be a general method to fabricate high performance fiber filaments of two-dimensional materials.

Hydrophobic Conductive Coatings for Fuel Cell Gas Diffusion Layers

Mass transfer of the reactant gases, water management, thermal and electrical conductivity are all highly depending on the properties of the gas diffusion layer (GDL) in polymer electrolyte fuel cells (PEFCs). GDLs are produced in complex and energy demanding processes including high temperature graphitization and are modified using polytetrafluoroethylene (PTFE) to introduce the hydrophobicity needed to efficiently remove water [1]. PTFE is, however, negatively impacts the required electrical conductivity and is facing an uncertain future with the pending restrictions on the use of perfluoroalkyl substances (PFAS) [2], [3]. Therefore, we have investigated the use of electrically conductive polyaniline (PANI) coatings on carbon fiber substrates with modifications to increase hydrophobicity. As substrate, AvCarb carbon paper EP40 was used and PTFE treated EP40T was used as state-of-the-art reference. EP40 was coated through dip-coating or electro-coating using PANI modified with sodium dodecylbenzenesulphonate as additive to adjust hydrophobicity [4]. With this approach, we have been able to show comparable pore volumes and pore surface areas (Figure 1) through mercury porosimetry as well as comparable hydrophobic properties.

Feasibility for High-Temperature Graphitization of Deformed Meager Coal.

The flattening of nanoscale pores is a crucial step in the process of anthracite graphitization, which primarily occurs due to lithostatic pressure or tectonic stress. Anthracite, a highly metamorphosed form of carbonaceous material, is a primary component of artificial graphite, but its availability is limited in China. Therefore, it is necessary to investigate the graphitization of low metamorphic coal. Note that the pores of deformed coal are substantially compressed, and the evolution of macromolecular structure is accelerated owing to strong tectonic extrusion and shearing action. Herein, the feasibility analysis of coal-based graphite at temperatures of 2200 and 2600 °C was investigated using mylonitized meager coal (YA-M; Ro,max = 2.34%), which exhibits the most intense deformation intensity, and it was compared with undeformed coal (YA-U; Ro,max = 1.87%) from the same coal seam. Results indicate that YA-U primarily consists of cylindrical pores with an average pore diameter of 10 nm, while YA-M exhibits extensive fine bottleneck and parallel plate pores with an average pore size of ∼4 nm. Additionally, interlayer spacing decreases from 0.3592 nm in YA-U to 0.3575 nm in YA-M, while crystallite height increases from 1.9633 nm in YA-U to 2.1424 nm in YA-M. The undeformed coal YA-U exhibits short and disordered aromatic fringes with a localized turbostratic structure that hinders graphitization. In contrast, YA-M exhibits more and longer localized fringe pairs arranged in parallel with improved structural ordering, indicating a favorable environment for graphitization. Ductile deformation narrows the pore diameter distribution, causing deformation pores on the mylonitic granules' surface to close, shrink directionally, collapse, or connect, resulting in obvious flattening characteristics of nanoscale. Based on these results, the graphitization degree of the graphitized products YA-GM-2200 and YA-GM-2600 was 80.23% and 88.37%, respectively, with interlayer spacings of 0.3371 and 0.3364 nm, indicating that these products have entered the semigraphite (medium graphitization) and graphite range, respectively. In contrast, the graphitization degree of YA-GU-2200 and YA-GU-2600 was only 51.16% and 56.98%, respectively, indicating that they have only progressed from anthracite to meta-anthracite (the preliminary graphitization stage). These findings confirm the view that the shear stress generated by the geological age flattens the pores of mylonitized meager coal and optimizes the aromatic lattice arrangement and orientation, facilitating graphitization and lowering the graphitization temperature (from 2800 to 2200 °C). Deformed coal is soft and can be easily crushed into powdered form using the human hand, making it less suitable for transportation. Additionally, owing to the unfavorable separation of minerals and lower hydrocarbon-generating potential, deformed coal application potential and price are consistently lower than those of undeformed coal. However, deformed coal is widely distributed in various coal measures in China, making these research findings valuable in promoting the high value-added utilization of low-rank deformed coal resources and expanding the carbon source of coal-based graphite materials.

Preparation and characteristic analysis of graphene based on coal macerals of different rank

Graphene is prepared using the improved Hummers redox method to study the preparation and structural characteristics of coal-based graphene from coal macerals of rank between 0.52 % and 1.98 %. The macerals are separated and enriched by hand sorting, sieving, and isopyknic gradient centrifugation. The crystal characteristics of the macerals, coal-based graphite, and graphene are characterized by XRD, Raman, SEM and TEM. The flake graphene with stable structure, good extensibility, different cell parameters and defects can be prepared from macerals. All the preparation yields are less than 4.0 %. The XRD data shows that after high-temperature graphitization, the layer spacing d002 of each sample is less than 0.3400 nm, and the lamellar crystallite sizes La and Lc are 7.70–21.09 nm and 11.53–16.94 nm, respectively. After the redox reaction, inertinite MLI-GS, YCWI-GS, and vitrinite GMDV-GS have the layer spacing d002, lamellar extendability La, stacking thickness Lc, and average stacking layer Nave that tend to be graphite-like structure. The microcrystalline structure is well developed and stable. Raman also confirmes that inertinite and high-rank vitrinite-derived graphene have fewer structural defects, good ordering, and a high degree of graphitization. The average values of ID/IG and AD/AG of maceral → coal-based graphite → graphene are 0.73 → 0.29 → 1.06, 2.12 → 0.40 → 1.62, indicating a relationship between the structural order: coal-based graphite > maceral > graphene, and between the degree of graphitization: coal-based graphite > graphene > maceral. The SEM and TEM dates show that inertinite tends to form a flat graphene structure with four–six layers, and has good light transmission. The graphene has few folds and warps, good layer extensibility, and high lattice order. The layer spacing at the edge is consistent with the d002 of XRD analysis. Vitrinite, cutinite, and barkinite derived graphene are similar to a kneaded paper balls. The layers are mixed with each other, forming more folds and ripples, and the peeling effect is poor. Only the high-rank GMDV-GS is clean like gauzy graphene, indicating that the micromorphological characteristics of graphene are related to the coal rank and macerals.

Effect of coal tar pitch modification on the structure and char yield of pyrolysis epoxy resin carbons

Epoxy resin carbons are of high strength, high temperature resistance, and corrosion resistance, which are widely used as the precursor of carbon composite materials. However, the applications of epoxy resin carbons are greatly limited for the characteristic of non-graphitization and low char yield (22 wt%). In this paper, coal tar pitch was used to modify epoxy resin carbons via a simple heating mixing, pyrolysis and high temperature graphitization. The results show that the coal tar pitch content and heat treatment temperature can improve the ordered graphite carbon content. As the coal tar pitch content increase, the ordered graphite carbon content of modified epoxy resin carbon increase after 3000 °C graphitization for 0.5 h. Particularly, the graphitization degree of epoxy resin carbon and 40 wt% coal tar pitch modified epoxy resin carbon are 8.42 % and 44.21 %, respectively. The grain size (Lc = 13.84 nm) and grain stacking height (La = 7.79 nm) of 40 wt% coal tar pitch modified epoxy resin carbon are bigger than epoxy resin carbon (Lc = 3.44 nm, La = 3.45 nm). The ordered coal tar pitch graphite carbon and disordered epoxy resin amorphous carbon are evenly distributed in the modified epoxy resin carbon, indicating a good comparability of coal tar pitch and epoxy resin. Besides, the entangling carbon ribbon are observed in the epoxy resin carbon after graphitization at 3000 °C. With the coal tar pitch content increasing, the carbon element content and aromatic ring number of modified epoxy resin increased. As the coal tar pitch content increase, the char yield and thermal decomposition temperature of modified epoxy resin gradually increase. The char yield of 50 wt% coal tar pitch modified epoxy resin is 42 wt%, almost double that of epoxy resin (22 wt%). The char yield increased values of modified epoxy resin mainly inherited the high char yield of coal tar pitch (50 wt%) and a small portion of char yield increased value is from the chemical crosslinking weight gain. When the coal tar pitch content is 40 wt%, the chemical crosslinking weight gain reaches the maximum value of 15 wt%. Possible chemical crosslinking reaction can be epoxy group and hydroxyl group of epoxy resin and carboxyl group and phenolic hydroxyl group of coal tar pitch. This study provides some theory foundation for the future application of epoxy resin carbon composite materials.

High-temperature graphitization characteristics of vitrinite and inertinite

In order to explore the graphitization characteristic differences between vitrinite and inertinite in coal, this study conducted high-temperature thermal simulation experiments (at five temperature points: 1800°C, 2100°C, 2400°C, 2700°C, and 3000°C) using inertinite-rich and vitrinite-rich samples as graphitization precursors. The quantitative comparison for the evolution characteristics of their graphite lattice was carried out using high-resolution transmission electron microscopy (HRTEM), X-ray diffractometer (XRD), and Raman spectroscopy (Raman) techniques. HRTEM revealed that an evident increase in carbon layer numbers and degree of extension was observed with increasing treatment temperature, XRD showed the variation of lattice parameters (d002/La/Lc) with temperature, Raman data revealed the variation of lattice defects (R2/R3) with temperature. It was discussed about the differences of graphite lattice construction processes between inertinite and vitrinite, throughout the entire temperature range of the experiment, the d002 spacing of inertinite was always smaller than that of vitrinite, indicating a higher degree of graphitization. vitrinite exhibited a uniform and smooth evolution state throughout the entire heating process, while inertinite exhibited an “inert” state between 1800°C and 2100°C (d002 values stagnated near at 0.3440 nm). With increasing simulated temperature, the defect level (R2 and R3) of vitrinite rapidly decreased below that of inertinite, throughout the entire temperature range, vitrinite demonstrated superior defect healing ability in terms of both rate and capability compared to inertinite. Under high-temperature thermal simulation, the three-dimensional lattice construction and defect elimination of vitrinite exhibited synchronous evolution characteristics. On the other hand, the formation of the graphite lattice in inertinite showed an evolutionary trend of “first three-dimensional lattice construction, followed by gradual defect elimination”.

Catalytic graphitization of coke and electrochemical performances of coke-based graphite

The effect of minerals on the high-temperature graphitization process of coke was thoroughly investigated using by X-ray diffraction (XRD), Raman spectroscopy (Raman), scanning electron microscope (SEM), physical adsorption instrument, etc. The structure-activity relationship between the microstructure of coke-based graphite and lithium storage performances was identified. The findings demonstrate that the microstructure of coke-based graphite is related to the mineral content and the final graphitization temperature affects the Si or Fe catalytic graphitization of coke. The appropriate amount of minerals as the catalyst can reduce the interlayer spacing, improve the graphitization degree and increase the crystallite size of the coke graphitization sample. The catalytic graphitization of coke involves the carbide transition, which is further confirmed by XRD and SEM-EDS analysis. By proper adding the mineral to the coke during the graphitization process, it is clear that the electrochemical performances of the synthetic graphite as anode for lithium-ion batteries can be improved obviously. Coke-based graphite DCG-20Si-2800 and DCG-30Fe-2800 as anode material show good comprehensive electrochemical performances. And the reversible specific capacities of both at 0.1 C are as high as 353.9 mAh/g and 361.9 mAh/g, respectively, which are quite close to the theoretical capacity of graphite (1 C = 372 mAh/g). Thus, the study successfully reveals the law of mineral catalysis in the graphitization process of coke and demonstrates the feasibility of coke-based graphite products as anode material. It can be expected that coke can be useful sources of artificial graphite if the graphitization process is adequately improved.

Defects boost graphitization for highly conductive graphene films.

Fabricating highly crystalline macroscopic films with extraordinary electrical and thermal conductivities from graphene sheets is essential for applications in electronics, telecommunications and thermal management. High-temperature graphitization is the only method known to date for the crystallization of all types of carbon materials, where defects are gradually removed with increasing temperature. However, when using graphene materials as precursors, including graphene oxide, reduced graphene oxide and pristine graphene, even lengthy graphitization at 3000°C can only produce graphene films with small grain sizes and abundant structural disorders, which limit their conductivities. Here, we show that high-temperature defects substantially accelerate the grain growth and ordering of graphene films during graphitization, enabling ideal AB stacking as well as a 100-fold, 64-fold and 28-fold improvement in grain size, electrical conductivity and thermal conductivity, respectively, between 2000°C and 3000°C. This process is realized by nitrogen doping, which retards the lattice restoration of defective graphene, retaining abundant defects such as vacancies, dislocations and grain boundaries in graphene films at a high temperature. With this approach, a highly ordered crystalline graphene film similar to highly oriented pyrolytic graphite is fabricated, with electrical and thermal conductivities (∼2.0× 104 S cm-1; ∼1.7 × 103W m-1 K-1) that are improved by about 6- and 2-fold, respectively, compared to those of the graphene films fabricated by graphene oxide. Such graphene film also exhibits a superhigh electromagnetic interference shielding effectiveness of ∼90dB at a thickness of 10μm, outperforming all the synthetic materials of comparable thickness including MXene films. This work not only paves the way for the technological application of highly conductive graphene films but also provides a general strategy to efficiently improve the synthesis and properties of other carbon materials such as graphene fibers, carbon nanotube fibers, carbon fibers, polymer-derived graphite and highly oriented pyrolytic graphite.

Rapid and low-cost carbon/carbon composites by using graphite slurry impregnated prepregs

A rapid and low-cost carbon/carbon (C/C) composites preparation method is proposed: graphite prepreg-coated carbon fiber fabric (CFF) is formed by hot pressing, followed by hot isostatic pressing and high temperature graphitization, to prepare C/C composite with low porosity and high crystallinity. In this method, the carbon fiber (CF) mass fraction can be precisely regulated in the range of 40–95% by the impregnation process conditions of CFF in graphite prepreg. The graphite particles in the preform were graphitized and bonded with CFF by high temperature graphitization. Finally, a ZrO2 anti-ablative layer was applied using sol-gel method. The results show that when the CF mass fraction is 50%, the C/C composite with a crystallinity of 92.21 and a porosity of 3.47% can be obtained, with mass ablation rate of 0.23 mg/s and density of 1.62 g/m3. The method can prepare C/C composites with uniform density and high ablation resistance.

High-temperature graphitization of coke and lithium storage properties of coke-based graphite

ABSTRACT Coal-derived carbon material is considered as a high-quality raw material for artificial graphite. Herein, the demineralized coke was prepared by acid washing, and coke-based graphite samples were prepared by high-temperature graphitization (2000°C–2800°C). The electrochemical performance of coke-based graphite samples was investigated. It is found that the high-temperature graphitization of the coke is inhibited by demineralization treatment. The graphitization degree of graphitized samples decreased after demineralization treatment. The graphitization degree of the graphitized samples at 2800°C from the raw coke and the demineralized coke can reach 74.48% and 68.78%, respectively. Chemical predemineralization treatment can reduce the mesoporous structure and specific surface area of the product. Moreover, onion-like graphite microspheres are found in graphitized samples from the coke before and after demineralization treatment. The order degree of the raw coke graphitization sample is significantly reduced by extending the graphitization preservation time. The electrochemical test results show that the graphitized sample, e.g., CG-2400, from raw coke (without demineralized) has better comprehensive electrochemical performance. The reversible specific capacity is 301.1 mAh/g at 0.1 C (1 C = 372 mAh/g). After 150 cycles at 1 C, the reversible specific capacity reaches 160.1 mAh/g.

Effect of Diatomite on the Thermal Degradation Behavior of Polypropylene and Formation of Graphene Products.

In this work, the thermogravimetry–Fourier transform infrared spectroscopy (TG–FTIR) and gas chromatography–mass spectrometry (GC–MS) techniques are used to investigate the thermal degradation behavior of polypropylene (PP) with 20 wt.% diatomite (DM). The initial decomposition temperature of these blends was 17 °C lower than that of pristine PP, and more olefin degradation products were formed during the pyrolysis process under Ar atmosphere. These results could be attributed to the catalytic effects of DM on the degradation of PP and the changes of PP chain scission pathways around the particles (more β scission happened via the secondary radical transfer). These olefins could be caught by DM through the Si–O–C bond formed during the heat–treatment around 400~500 °C. The formation of the cross–linked structure could facilitate the growth of graphene during a high–temperature graphitization process.

Hierarchic porous graphite/reduced graphene oxide composites generated from semi-coke as high-performance anodes for lithium-ion batteries

Graphite has widely been used as anode material for lithium ion batteries, though its electrochemical performances, such as the lithium ion storage capacity and lithiation/delithiation rate capability, are remained to be improved. Herein, porous graphite is fabricated through high temperature graphitization of semi-coke followed by catalytic pore-creation procedure. The as-obtained porous graphite particles were cladded with reduced graphene oxide sheets, which exfoliated with the as-graphitized semi-coke, resulting three-dimensional hierarchic porous graphite/rGO composites. The unique hierarchic porous architecture not only facilitate the transfer of electrons, diffusion of lithium ions and interfacial charge transfer, but can also provide more active sites for lithium ion anchoring, thus improve greatly the overall electrochemical performances of the composites as anode. The composite with appropriate porous graphite to reduced graphene oxide ratio shows a reversible capacity of 460.1 mAh/g at 0.1 A/g and a capacity retention of almost 80% (377.3 mAh/g) at 1 A/g, much better than those of pristine graphite (28% retention), along with excellent cycling stability with >99% capacity retention after 300 cycles. This work may blaze a novel route to convert the low-cost and resourceful coal products to high performance anode materials for lithium-ion batteries and other energy storage systems.

Artificial three-dimensional inverse opal cathode host materials for lithium sulfur batteries

Lithium-sulfur batteries (LSBs) are regarded as promising energy storage devices due to their high theoretical capacity. However, LSBs face great challenge in commercial uses due to their “shuttle effect”. In this work, a composite material consisting of N and O heteroatoms dispersed on three-dimensional macroporous glycine anhydride (3DMPGA) inverse opal structure is designed and synthesized by the one-step method. Compared with high temperature graphitization, low temperature pyrolysis of 3DMPGA consumes less energy. And precursor glycine is renewable, which is significant for reducing carbon emissions. The results show that 3DMPGA has an ordered porous inverse opal structure and uniform heteroatoms distribution. Lithium polysulfides are not only stored in the pores with spatial confinement but also anchored on the surface of pores via chemical adsorption, confirmed by adsorption tests and density functional theory calculation, respectively. The initial capacity of the 3DMPGA cathode at 0.5C is 848 mAh g−1, and the average attenuation rate for 300 cycles is only 0.14%. At a higher C-rate, the enhanced electrochemical performance of 3DMPGA is more obvious due to the dual-effect on mitigating the “shuttle effect”.

High-temperature deoxygenation-created highly porous graphitic carbon nanosheets for ultrahigh-rate supercapacitive energy storage

Developing carbon-based supercapacitors with high rate capability is of great importance to meet the emerging demands for devices that requires high energy density as well as high power density. However, it is hard to fabricate a nanocarbon with high electro-active surface area meanwhile maintaining superior conductivity to ensure the high rate capability since excellent conductivity is usually realized by high temperature graphitization, which would lead to the structural collapse and sintering resulting in low surface area. Herein, we reported a highly porous graphitic carbon nanosheet with an unprecedented rate capability of 98% of its initial capacitance from 0.5 to 50 A/g for ultrahigh-rate supercapacitive energy storage. These hierarchical mesoporous carbon nanosheets (HMCN) were fabricated by a template induced catalytic graphitization approach, in which sheet-like Mg(OH)2 was employed as catalytic template in situ catalytically polymerizing of catechol and formaldehyde and catalytically graphitizing of the formed carbon skeleton. Upon the co-effect of template (avoiding the sintering) and the deoxygenation (creating the pores) during the high temperature graphitization process, the obtained HMCN material possesses nanosheet morphology with highly porous graphitic microstructure rich in mesoporosity, large in surface area (2316 m2/g), large in pore volume (3.58 cm3/g) and excellent in conductivity (109.8 S/cm). In 1.0 M TEABF4/AN, HMCN exhibits superior supercapacitive performance including large energy density of 52.2 Wh/kg at high power density of 118 kW/kg, long-cycling stability and excellent rate capability, making HMCN a promising electrode material for supercapacitor devices.

Study on Structural Evolution of Synthetic Graphite Derived from Lignite Prepared by High Temperature–High Pressure Method

Abundant and cheap lignite is regarded as inferior fuel due to its disadvantages such as low heat and high moisture. In order to realize the high value and clean, non-fuel utilization of lignite, we used lignite as precursor to prepare high-quality synthetic graphite through graphitization treatment using the high temperature–high pressure (HTHP) method, and afterwards characterized the samples by XRD, Raman, FTIR, SEM-EDS, and HRTEM, and systematically analyzed the effect of P-T conditions on the structure evolution of lignite. Our results demonstrated that temperature dominates the graphitization of lignite, and high pressure accelerates the graphitization process of lignite. Under HTHP treatment, the aromatic layer of lignite accelerates directional rearrangement; the ordered domain increases rapidly, and the ductility and stacking degree of the carbon sheets of the lignite sample are greatly enhanced. Compared with the traditional high-temperature graphitization method, the HTHP method greatly reduces the graphitization temperature and shortens the graphitization time. Remarkably, the as-prepared graphite with a graphitization degree of 91.87% superior to graphite fabricated by the conventional high-temperature processing were rapidly prepared from lignite at 6 GPa and 1300 °C in 20 min. This study demonstrates that the HTHP method is a feasible and effective method to realize the green, efficient, and high value utilization of lignite.

Enhanced both in-plane and through-thickness thermal conductivity of carbon fiber/epoxy composites by fabricating high thermal conductive coaxial PAN/PBO carbon fibers

PAN-based carbon fibers (PAN-CFs) have been widely used as structural reinforcements of various advanced composites due to their excellent mechanical properties. However, PAN-CFs have no obvious superiority in terms of the heat dissipation ability compared to mesophase pitch-based CFs and vapor grown CFs. In the present work, Poly- p -phenylene benzobisoxazole (PBO) macromolecules, which could contribute to the development of highly ordered graphite from conjugated aromatic backbone, were introduced onto PAN-CF surfaces to prepare coaxial PAN/PBO carbon fibers (PAN/PBO-CFs). Results showed that functional graphene oxide (GO) could result in uniform grafting of PBO macromolecules onto fiber surfaces owing to π–π conjugations between GO and benzoxazole backbone. The coaxial PAN/PBO-CFs were subsequently obtained through high-temperature graphitization and the rigid state could be also retained. Results by XRD and TEM demonstrated that PAN/PBO-CFs had smaller interlayer spacing and higher crystallinity compared to PAN-CF, and PBO derived graphite crystals could also be perpendicular to fiber surfaces. As for the thermal conductivity of composites, the in-plane thermal conductivity of PAN/PBO-CF reinforced epoxy composite was as high as 82.86 W/(m·K) which was almost 1.5 times of PAN-CF/epoxy composites, and the through-thickness thermal conductivity with the value of 2.54 W/(m·K) also increased by 65%. The introduction of PBO macromolecules could contribute new conductive paths and alleviate the problem of interfacial temperature gradients between CF and resin matrix . As a result, thermal conductivity properties of coaxial PAN/PBO-CF reinforced composites significantly improved.

High Temperature Continuous Gas Purification and Graphitization System and Process for Carbon Particulate Materials

With the continuous development of modern science and technology, more and more new materials have been applied to production and life. As a new material, carbon granular material is made of carbon, graphite materials and other various raw materials with high carbon content through a series of processing technologies. China is one of the most widely used carbon materials in the world. The purpose of this paper is to optimize and enhance the application effect of carbon materials and promote the construction of a new economic model of energy conservation and emission reduction in China. The specific research is as follows:

Advances in the Safe Disposal and Comprehensive Utilization of Spent Carbon Anode From Aluminum Electrolysis: Prospects for Extraction and Application of Carbon Resources From Hazardous Waste

Spent carbon anode (SCA) is a dangerous solid waste that is continuously discharged from the aluminum electrolysis industry and has a large number of valuable resources and a high risk of environmental pollution. Its safe disposal and resource utilization have become a resource and environmental problem that must be solved urgently. Current methods for SCA disposal include flotation, vacuum metallurgy, physical activation, roasting, bubbling fluidized bed combustion, alkali fusion, alkali leaching, and chemical leaching combined with high temperature graphitization. In this paper, the material composition, resource properties, and environmental risks of SCA are discussed. Working principle, treatment process, advantages and disadvantages of the above methods are also briefly described and compared. Results showed that flotation is the safest disposal and comprehensive utilization technology that is suitable for characteristics of SCA raw materials and has the most large-scale application potential. In addition, characteristics of SCA recovery products are correlated to the recycling of aluminum reduction cells. This technology can alleviate the shortage of high-quality petroleum coke resources in China’s carbon material industry and the high cost of raw materials in aluminum electrolysis industry.

Regulating microstructures of soft carbon anodes by terminations of Ti3C2T MXene toward fast and stable sodium storage

Soft carbon features low-cost and high-carbon-yield advantages but possesses highly graphitized structures at high pyrolysis temperatures, limiting its application as anode for the sodium (Na) storage technologies. Herein, a novel strategy is devised to retard the high-temperature graphitization and regulate the microstructure of pitch by the terminations of Ti 3 C 2 T x MXene. The abundant and easily releasable terminations influence the cross-linking degree of precursor by consuming the intrinsic hydrogen, realizing a carbon structural transformation from ordered to disordered. Benefiting from the disordered graphitic structure and large d 002 -spacing, the insertion-dominated Na storage capability of pitch is inspired with a threefold increase in specific capacity. In addition, a series of “TiC-oriented carbon” structures favoring fast Na storage kinetics are constructed to elaborate the correlation of Na storage behavior dependence on the carbon structural evolution. This strategy is expected to be extended to other soft carbon precursors and help improve the understanding of Na storage mechanism in disordered carbon. Pitch-derived soft carbon processes a major challenge of high-temperature graphitization, limiting it as the promising anode for Na storage. The terminations of Ti 3 C 2 T x MXene are utilized for retarding the graphitization and regulating the microstructure. The structural transformation from PP1400 to TiC@C-3 toggles the Na storage mechanism switch of soft carbon from “adsorption” to “adsorption–insertion”, thus achieving high specific capacity. • Retarding the high-temperature graphitization of pitch by the terminations of Ti 3 C 2 T x MXene. • Opening the insertion-dominated sodium storage capability of pitch-derived carbon. • Probing the sodium storage mechanism in disordered carbon.