Control of the properties of a binder pitch to enhance the density and strength of graphite blocks

Kim, Ji Hong

doi:10.1007/s42823-023-00515-1

Cited by 11 publications

(8 citation statements)

References 40 publications

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“…The true density was assumed to be the volume excluding the pores. The open pore, closed pore, and total porosity of the graphite block were calculated using Equations ( 1)-(3), as follows [25]:…”

Section: Characterization Of Assembled Anodementioning

confidence: 99%

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

Choi,

Lee,

Kim

et al. 2023

Materials

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We investigate the reassembly techniques for utilizing fine graphite particles, smaller than 5 µm, as high-efficiency, high-rate anode materials for lithium-ion batteries. Fine graphite particles of two sizes (0.4–1.2 µm and 5 µm) are utilized, and the mixing ratio of the two particles is varied to control the porosity of the assembled graphite. The packing characteristics of the assembled graphite change based on the mixing ratio of the two types of fine graphite particles, forming assembled graphite with varying porosities. The open porosity of the manufactured assembled graphite samples ranges from 0.94% to 3.55%, while the closed porosity ranges from 21.41% to 26.51%. All the assembled graphite shows improved electrochemical characteristics properties compared with anodes composed solely of fine graphite particles without granulation. The sample assembled by mixing 1.2 µm and 5 µm graphite at a 60:40 ratio exhibits the lowest total porosity (27.45%). Moreover, it exhibits a 92.3% initial Coulombic efficiency (a 4.7% improvement over fine graphite particles) and a capacity of 163.4 mAh/g at a 5C-rate (a 1.9-fold improvement over fine graphite particles).

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Section: Characterization Of Assembled Anodementioning

confidence: 99%

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

Choi,

Lee,

Kim

et al. 2023

Materials

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“…CTP is a residue substance generated when distilling or heat-treating coal tar [1]. Specifically, CTP is composed of various types of aromatic hydrocarbons and heterocycles [2,3]. Thanks to this structural characteristic, its molecular weight can be tailored as needed, enabling it to serve as a binder or an impregnating agent [4].…”

Section: Introductionmentioning

confidence: 99%

Changes in Functional Groups and Crystal Structure of Coal Tar Pitch with Respect to Carbonization Temperature

Lee,

Roh

2024

Crystals

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In this study, changes in the microstructure of coal-tar pitch (CTP) during successive processes, including pyrolysis, polycondensation, and crystallization, were examined in connection with the resulting variations in structure factors, as measured by X-ray diffraction (XRD) analysis, and functional groups, as confirmed by Fourier transform infrared (FTIR) spectroscopy. To this end, four zones were defined based on variations in crystallinity, which were indicated by d002 and Lc. Each zone was further characterized by interpreting crystallinity development in relation to changes in functional groups and specimen height. At around 400 °C, polycondensation occurred as the C-Har and C-Hal peaks decreased in intensity. These peak reductions coincided with the formation of mesophase spheres, resulting in enhanced crystallinity. Subsequently, at around 500 °C, the peak intensity of C-H and COOH decreased, which was attributed to the release of large amounts of gases. This led to sharp volume changes and a temporary reduction in crystallinity. All these results suggest that changes in the functional groups of CTP at lower temperatures (600 °C or less) during the carbonization process are closely associated with variations in its crystallinity. The major findings of the present study provide valuable insights for designing highly effective processes in the manufacturing of synthetic graphite blocks using CTP as a binder material, including by selecting appropriate temperature ranges to minimize volume expansion and crystallinity degradation and determining the lowest possible carbonization temperature to ensure adequate binder strength.

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“…They are also used as final products intended for use at around 1000 • C. The forming process throughout the entire procedure is conducted in either unidirectional pressing mode or cold isostatic pressing (CIP) mode. The choice of mode determines the directional strength and electrical conductivity of the resulting carbon blocks and graphite blocks [1,[10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Effect of Microstructural Change under Pressure during Isostatic Pressing on Mechanical and Electrical Properties of Isotropic Carbon Blocks

Byun,

Lee,

Kim

et al. 2024

Materials

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In this study, carbon blocks were fabricated using isotropic coke and coal tar pitch as raw materials, with a variation in pressure during cold isostatic pressing (CIP). The CIP pressure was set to 50, 100, 150, and 200 MPa, and the effect of the CIP pressure on the mechanical and electrical properties of the resulting carbon blocks was analyzed. Microstructural observations confirmed that, after the kneading, the surface of isotropic coke was covered with the pitch components. Subsequently, after the CIP, granules, which were larger than isotropic coke and the kneaded particles, were observed. The formation of these granules was attributed to the coalescence of kneaded particles under the applied pressing pressure. This granule formation was accompanied by the development of pores, some remaining within the granules, while others were extruded, thereby existing externally. The increase in the applied pressing pressure facilitated the formation of granules, and this microstructural development contributed to enhanced mechanical and electrical properties. At a pressing pressure of 100 MPa, the maximum flexural strength was achieved at 33.3 MPa, and the minimum electrical resistivity was reached at 60.1 μΩm. The higher the pressing pressure, the larger the size of the granules. Pores around the granules tended to connect and grow larger, forming crack-like structures. This microstructural change led to degraded mechanical and electrical properties. The isotropic ratio of the carbon blocks obtained in this study was estimated based on the coefficient of thermal expansion (CTE). The results confirmed that all carbon blocks obtained proved to be isotropic. In this study, a specimen type named CIP-100 exhibited the best performance in every aspect as an isotropic carbon block.

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Control of the properties of a binder pitch to enhance the density and strength of graphite blocks

Cited by 11 publications

References 40 publications

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

Optimization of Pore Characteristics of Graphite-Based Anode for Li-Ion Batteries by Control of the Particle Size Distribution

Changes in Functional Groups and Crystal Structure of Coal Tar Pitch with Respect to Carbonization Temperature

Effect of Microstructural Change under Pressure during Isostatic Pressing on Mechanical and Electrical Properties of Isotropic Carbon Blocks

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