Pitch Carbon Research Articles

(Digital Presentation) Rational Material Design on Long-Term-Cyclability of Graphite/Si-based Anode for Room Temperature All-Solid-State Batteries

Graphite, a lithium intercalaion-type host, is considered as the most commercially available anode material for secondary batteries. However, mojor issues on poor kinetics, a low capacity, and interfacial reaction with sulfide solid electrolytes hinders the introduction of graphite to all solid-state batteries (ASSBs). Here we propose a rational material design on graphite/Si-based anodes for high capacity and long-cycle-life ASSBs. A mechano-fusion process is used to synthesize hetero-aggregates with a core-shell structure, where (sub-)micron SiOx particles are anchord on the surface of graphite host particles (10-20 µm). As-prepared SiO x /graphite composite (SGC) is covered with a carbon layer (~10nm) by pitch conating and thermal treatment (C@SGC). The ASSB is fabricated with Li-metal as a counter electrode and an anode with the C@SGC and Li6PS5Cl in a weigh ratio of 8 : 2. When tested at 25℃ and undr 25 MPa, it delivers a initial discharge capacity of 706 mAh g− 1 and a high capacity retention of 89% over 200 cycles. Monitoring of a swelling behavior shows 2% of a negligible volume change after charge/discharge, in contrast to 33% for a LIB system, leads to a good interfacial solid-solid contacts and electrode integrity. We further reveals that the pitch carbon coating largely suppress the side reaction between the SGC and the Li6PS5Cl. Our design strategy on materials opens up new possibility for the graphite/Si-based anode for room-terperature all-solid-state battery.

N-Doped Porous Carbon Based on Anion and Cation Storage Chemistry for High-Energy and Power-Density Zinc Ion Capacitor.

Zinc ion hybrid capacitors (ZIHCs) show promise for large-scale energy storage because of their low cost, highly intrinsic safety, and eco-friendliness. However, their energy density has been limited by the lack of advanced cathodes. Herein, a high-capacity cathode material named N-doped porous carbon (CFeN-2) is introduced for ZIHCs. CFeN-2, synthesized through the annealing of coal pitch with FeCl3·6H2O as a catalytic activator and melamine as a nitrogen source, exhibits significant N content (10.95 wt%), a large surface area (1037.66 m2 g-1), abundant lattice defects and ultrahigh microporosity. These characteristics, validated through theoretical simulations and experimental tests, enable a dual-ion energy storage mechanism involving Zn2+ ions and CF3SO3 - anions for CFeN-2. When used as a cathode in ZIHCs, CFeN-2 achieves a high-energy density of 142.5W h kg-1 and a high-power density of 9500.1W kg-1. Furthermore, using CFeN-2 ZIHCs demonstrate exceptional performance with 77% capacity retention and nearly 100% coulombic efficiency after 10 000 cycles at 10 A g-1, showcasing substantially superior performance to current ZIHCs. This study offers a pathway for developing high-energy and high-power cathodes derived from coal pitch carbon for ZIHC applications.

Synergistic effect of spinning drawing and preoxidation stretching on the orientation structure of mesophase pitch carbon fibers

Synergistic effect of spinning drawing and preoxidation stretching on the orientation structure of mesophase pitch carbon fibers

Tuning Microstructure of Mesophase Pitch Carbon Fiber by Altering the Carbonization Ramp Rate

The microstructure of mesophase pitch carbon fibers (CFs) are tuned by varying ramp rates from 1 to 50 °C min−1 up to 1000 °C to study the effect of ramp rate on CFs’ microstructure, thermal and mechanical properties with the goal of offsetting the cost by decreasing cycle time. The ramp rates represent carbonization times ranging from 16.4 to 1.17 h, not including cool down. Differential scanning calorimetry, thermogravimetric analysis, and derivative thermogravimetry are used to investigate the impact ramp rate has on the thermal properties of mesophase pitch. It is found that lower ramp rates are endothermic in nature with a lower temperature onset and maximum weight loss. Higher ramp rates possess an exothermic nature with higher temperatures resulting in maximal weight loss over a smaller range of temperatures. Mechanical testing shows varying CF strengths and moduli dependent on ramp rate and an optimized process is developed to produce the strongest CF. Microstructural characterization revealed that faster ramp rates lead to smaller interplanar spacings and larger crystallites but possessed greater disorder.

High stiffness 3D-printed continuous pitch carbon fiber reinforced polymer composites

This study presents a method for 3D printing very high stiffness pitch-based carbon fiber (CF) reinforced polylactic acid (PLA) composites using a modified open-source 3D printer. The fused filament fabrication (FFF) technique was used to fabricate the samples with alternating layers of PLA and PLA-coated pitch CF. The tensile Young’s modulus of the 3D-printed composite samples was measured to characterize the effect of different grades and volume fractions of pitch CF on the behaviour of the printed composites. Three grades of pitch CF which have different Young’s modulus were used with volume fractions ranging from 2.4 to 8.4%. Tensile tests showed that the K1392U CF reinforced composite with a 7.3% volume fraction demonstrated the highest improvement in Young’s modulus of 850% compared to neat 3D-printed PLA. This improvement is notably higher than any previous 3D-printed carbon-based composites at a relatively low volume fraction of CF. Statistical analysis showed increased Young’s modulus in all of 3D-printed composite samples tested. The experimental values were compared to the Halpin-Tsai model and suggest that some degree of fibre breakage occurred during the 3D printing process owing to the relative stiffness of the pitch-based fibers. Future directions and suggestions for process improvements are discussed.

Hydrolysis of Cellulose using boronic-acid multifunctional carbocatalysts

Hydrolysis of Cellulose using boronic-acid multifunctional carbocatalysts

High thermal conductivity continuous pitch carbon fiber 3D printed using a 6-axis robot arm

High thermal conductivity continuous pitch carbon fiber 3D printed using a 6-axis robot arm

Effect of Carbonization Temperature on the Structure of Pitch Carbon and Its Low-temperature Lithium Storage Properties

Introduction:: Lithium-ion batteries were one of the most promising battery systems for electric vehicles. Currently, lithium-ion batteries are required to have higher energy density and cycle stability. The traditional graphite negative electrode cannot meet the requirements. Pitch has many advantages such as wide source, low cost, high carbon residue rate and easy graphitization, as a carbon precursor has been widely used in lithium-ion battery anode and anode materials. Method:: In this paper, pitch carbon was prepared by carbonization at different temperatures and studied. Result:: The results showed that with the increase of carbonization temperature, the interlayer spacing decreased gradually, the degree of amorphousness decreases gradually, the specific surface area and pore volume also decrease gradually, the initial coulombic efficiency and capacity retention increased, and the discharge-specific capacity decreased. Galvanostatic Intermittent Titration Technique (GITT) tests show that there are two main mechanisms of lithium ions intercalation in the material, surface adsorption and interlayer intercalation. Conclusion:: The difficulty of diffusion of lithium ions between pitch carbon layers at low temperatures is the main reason for the decrease of its capacity at low temperature. The carbon material obtained by carbonization of pitch at 800℃ has the best low temperature performance, with discharge specific capacities of 335, 272, 232 and 187mAh/g at 25, 0, -20 and -40℃, of which 55.8% of the discharge specific capacity at room temperature can be retained at -40℃. The amorphous carbon material has certain low temperature charge-discharge performance.

Stabilization time and temperature influence on the evolution of the properties of mesophase pitch stabilized fibers and carbon fibers

Stabilization time and temperature influence on the evolution of the properties of mesophase pitch stabilized fibers and carbon fibers

Characterization of pitch carbon coating properties affecting the electrochemical behavior of silicon nanoparticle lithium-ion battery anodes

700 °C is the optimal heat treatment temperature for pitch-coated silicon electrodes. Both the amorphous carbon/pitch and silicon are active materials but store Li+ ions through different ion storage mechanisms and contribute to overall performance.

Porous MnO/pitch carbon composite as an anode material for low-cost and high-performance lithium-ion battery

Porous MnO/pitch carbon composite as an anode material for low-cost and high-performance lithium-ion battery

A durable quasi-solid-state zinc ion hybrid supercapacitor with coal tar pitch derived carbon material

A durable quasi-solid-state zinc ion hybrid supercapacitor with coal tar pitch derived carbon material

Hydrogenation of coal tar pitch for improved mesophase pitch molecular orientation and carbon fiber processing

Hydrogenation of coal tar pitch for improved mesophase pitch molecular orientation and carbon fiber processing

Pitch Carbon‐coated Ultrasmall Si Nanoparticle Lithium‐ion Battery Anodes Exhibiting Reduced Reactivity with Carbonate‐based Electrolyte

AbstractSilicon anodes for lithium‐ion batteries (LIBs) have the potential for higher energy density compared to conventionally used graphite‐based LIB anodes. However, silicon anodes exhibit poor cycle and calendar lifetimes due to mechanical instabilities and high chemical and electrochemical reactivity with the carbonate‐based electrolytes that are typically used in LIBs. In this work, we synthesize a pitch carbon‐coated silicon nanoparticle composite active material for LIB anodes that exhibits reduced chemical reactivity with carbonate‐based electrolytes compared to an uncoated silicon anode. Silicon primary particle sizes less than 10 nm diameter minimize micro‐scale mechanical degradation of the anode composite, while conformal coatings of pitch carbon minimize the parasitic reactions between the silicon and the electrolyte. When matched with a high voltage NMC622 (LiNi0.6Mn0.2Co0.2O2) cathode, the pitch carbon‐coated silicon anode retains ≈75 % of its initial capacity at the end of 1000 cycles. Increasing the areal loading of the pitch carbon‐coated silicon anodes to realize energy density improvements over graphite anodes results in severe mechanical degradation on the electrode level, highlighting a remaining challenge to be addressed in future work.

Influence of Oxygen Uptake on Pitch Carbon Fiber.

Carbon fiber precursor materials, such as polyacrylonitrile, pitch, and cellulose/rayon, require thermal stabilization to maintain structural integrity during conversion into carbon fiber. Thermal stabilization mitigates undesirable decomposition and liquification of the fibers during the carbonization process. Generally, the thermal stabilization of mesophase pitch consists of the attachment of oxygen-containing functional groups onto the polymeric structure. In this study, the oxidation of mesophase pitch precursor fibers at various weight percentage increases (1, 3.5, 5, 7.5 wt%) and temperatures (260, 280, 290 °C) using in situ differential scanning calorimetry and thermogravimetric analysis isinvestigated. The results areanalyzed to determine the effect of temperature and weight percentage increase on the stabilization process of the fibers, and the fibers aresubsequently carbonized and tested for tensile mechanical performance. Thefindings provide insight into the relationship between stabilization conditions, fiber microstructure, and mechanical properties of the resulting carbon fibers.

Thermal conductivity of 3D-printed continuous pitch carbon fiber composites

Thermal conductivity of 3D-printed continuous pitch carbon fiber composites

Evolution of the Composition and Melting Behavior of Spinnable Pitch during Incubation.

The physical and chemical properties of spinnable pitch showed a huge impact on the performance of resultant pitch carbon fiber even if its physical and chemical properties were slightly changed. Various polycyclic aromatic compounds and abundant free radicals existed in spinnable pitch, and there are many interactions among molecules and free radicals. The molecular structure and composition of spinnable pitch were investigated during incubation, and the effect of molecular evaluation on rheological properties of spinnable pitch was illustrated using various characterization methods in this work. It indicated that n-hexane soluble fraction mainly occurred condensation or cleavage, and a small number of heavy components were generated after a long period. The fraction of n-hexane insoluble/toluene soluble underwent molecular condensation and cross-linking in the presence of oxygen-containing radicals and aromatic hydrocarbon radicals, while toluene insoluble/tetrahydrofuran soluble fraction tended to change in large molecules of polycyclic aromatic hydrocarbons. Lastly, tetrahydrofuran insoluble fraction was condensed due to its high aromaticity during the incubation process, and the content of aromatic carbon increased. These changes of composition and structure of spinnable pitch led to its softening point, increase in viscosity and flow activation energy, and deterioration of the rheological property.

Mechanism for the catalytic thermal polycondensation of naphthalene at low temperature

Naphthalene is an important component of high temperature coal tar and its content can reach more than 10%. Catalytic polycondensation of naphthalene is an effective way to prepare mesophase pitch and functional carbon materials. In this work, anhydrous AlCl 3 was used as a catalyst for the polymerization of naphthalene under atmospheric pressure below 170 °C and the reaction mechanism was then systematically investigated. The results indicate that at 110 °C, the polymer product is mainly composed of tricyclic compounds and the content of heavy products is only 29.5%. At 150 °C, four to five peri-condensed aromatic compounds turn to be the main components and the content of medium components remains about 50%. At 170 °C, there appear a large number of six-ring aromatic cores and the conversion of naphthalene reaches 90.7%. The polymer products exhibit good fluidity and solubility in THF, which can facilitate the high-temperature thermal polycondensation and subsequent graphitization process. With an AlCl 3 /naphthalene molar ratio of 1/100, the second to seventh order naphthalene oligomers are obtained by the simulation of the short chain oligomerization of naphthalene. In contrast, when the AlCl 3 /naphthalene molar ratio exceeds 10/100, acetylene and methylnaphthalene are produced by the catalytic pyrolysis of naphthalene. The mechanism of “Oligomerization-Pyrolysis-Aromatization” was then proposed to explain the molecular transformation from naphthalene to pitch, which should be useful for the production of mesophase pitch precursor.

High conductivity and stability intercalated carbonaceous conductors

• Copper chloride intercalation is scalable and stable up to 500K • It enhances electrical conductivity of different carbonaceous conductors by 10X • Intercalated carbon fibers achieve a 10MS/m electrical conductivity • Intercalation results in a one-step impurity purification and conductivity enhancement • Conduction in CNT yarns is hampered significantly by internal junction resistances Carbonaceous conductors have attracted great interest due to their low density and superior mechanical and chemical properties. Metal halide intercalation is an effective approach for enhancing the electrical conductivity of these conductors. This paper investigates the microstructure, composition, electrical, and mechanical properties of different carbonaceous conductors (pitch carbon fiber, three types of carbon nanotube yarns, and graphene fiber) intercalated with copper chloride. Temperature-dependent conductivity measurements along with Raman spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy reveal the degree of intercalation in different samples. Intercalated specimens exhibit electrical conductivities at least seven-fold higher than their pristine counterparts, including a 10 MS/m conductivity for intercalated carbon fibers. Interestingly, the intercalation process results in a one-step impurity purification and conductivity enhancement in CNT yarns. Electrical conductivity measurements over cryogenic and elevated temperature ranges (30-500 K) explain conduction mechanisms and demonstrate intercalant stability. This study informs future applications of lightweight conductors by presenting a library of different carbon-based conductors and their structural and property variations. :

Effect of graphitization temperature on microstructure, mechanical and ablative properties of C/C composites with pitch and pyrocarbon dual-matrix

Two graphitized C/C composites with a density of 1.83 g/cm3 were fabricated by CVI, high-pressure liquid-phase carbonization, and graphitization process. After graphitization at 2500 and 3000 °C, the graphitization degree of carbon phases in both composites shows a trend of pitch carbon > pyrocarbon > PAN carbon fiber. With increasing graphitization temperature, the orderly arrangement and growth of the graphite microcrystals cause the improved graphitization degree of the composites. Therefore, the thermal conductivity increases from 68.78 to 126.09 W/(m·K) in the transverse direction and 31.09 to 75.60 W/(m·K) in the thickness direction. Meanwhile, the increase in micro-cracks and pores formed at the interface induced the declined flexural and compressive strength, with the corresponding strength reducing to 104.17 and 113.92 MPa, respectively. During the first 22 s of ablation, the improved graphitization degree and higher thermal conductivity can transfer the heat rapidly, resulting in a lower surface temperature and a higher backside temperature. After 30 s ablation, the mass ablation rate decreases from 0.0030 to 0.0018 g/s, while the linear ablation rate increases from 0.0040 to 0.0093 mm/s due to the increased open porosity and defects under higher graphitization temperature.