Graphite Research Articles

Microscopic Mechanism of the Intercalation Behavior of AlCl4 - in Graphite Cathode Materials of Aluminum-ion Batteries.

Rechargeable aluminum-ion batteries with graphite as cathode material are highly attractive for energy storage due to their low cost, high abundance, and high capacity. Although some techniques have been employed to investigate intercalation/deintercalation behavior of AlCl4 - in graphite materials, the microscopic mechanism remains ambiguous and controversial, leading to a question that needs to be answered. Therefore, direct and in-situ characterization of nanoscale variations in the z direction is a reliable avenue to finding the answer to the intercalation stage mechanism. In this work, in-situ AFM was used to directly monitor the intercalation/deintercalation process of AlCl4 - in highly oriented pyrolytic graphite, pyrolytic graphite and natural graphite electrode materials. We demonstrate that during the initial stage of intercalation, AlCl4 - ions tend to intercalate intensively into the same graphite layer, and that as potential increases the intercalation of AlCl4 - ions displays a mixed-staged process. Moreover, during the intercalation of AlCl4 - into the pyrolytic graphite electrode, noticeable exfoliation of the graphite layers was observed. This phenomenon accounts for the energy loss that occurs in the initial cycles of the graphite/Al battery system. Finally, we propose an optimization strategy to prevent exfoliation.

Structural and optical properties of ZnS/rGO nanocomposites optoelectronic devices

This paper investigates the impact of reduced graphene oxide (rGO) addition on the structural and optical properties of ZnS nanocomposites. The study began with the synthesis of graphene oxide (GO) through the oxidation of natural graphite powder. This process involved using potassium permanganate in a mixture of sulfuric and phosphoric acids, maintained at 50°C for 48 hours. The reaction was terminated using hydrogen peroxide, followed by purification and drying, yielding 1.5 grams of GO. The preparation of ZnS/GO nanocomposites involved dissolving zinc acetate and varying quantities of GO in water, adjusting the pH, and incorporating sodium sulfide. This mixture underwent heating in an autoclave at 180°C for 12 hours, followed by washing and freezing, resulting in ZnS-RGO composites with differing GO contents. The resulting products were categorized as ZnS0rGO, ZnS-5rGO, ZnS-10rGO, ZnS-15rGO, and ZnS-20rGO. To characterize these composite samples, the researchers employed several analytical techniques, including thermogravimetric analysis (TGA), X-ray diffraction (XRD) analysis, X-ray Photoelectron Spectroscopy (XPS), and UV-vis spectroscopy. This comprehensive approach allowed for a thorough examination of the effects of rGO incorporation on the nanocomposite's properties. The X-ray diffraction (XRD) results showed increased diffraction intensity with higher rGO content, attributed to improved crystallinity. The crystallite size and lattice strain also increased, with rGO providing nucleation sites. Optical analysis revealed that rGO increased absorbance and decreased the optical band gap, likely due to enhanced free charge carriers. The extinction coefficient and nonlinear refractive index both increased with rGO content, attributed to rGO’s high polarizability and light-matter interactions.

The comprehensive properties and microstructures of matrix graphite for high-temperature gas-cooled reactor: Effects of particle size of nuclear-grade natural graphite powder

The comprehensive properties and microstructures of matrix graphite for high-temperature gas-cooled reactor: Effects of particle size of nuclear-grade natural graphite powder

Large-area high thermal conductivity graphite-carboxymethylcellulose film easily produced by mechanical exfoliation of natural graphite using a three-roll mill

Large-area high thermal conductivity graphite-carboxymethylcellulose film easily produced by mechanical exfoliation of natural graphite using a three-roll mill

Effect of multi-walled carbon nanotubes on the properties of composite bipolar plate for polymer electrolyte membrane fuel cells

Abstract Polymer Composite Bipolar Plates (PCBP) with carbon fillers are emerging as a lightweight and compact alternative to pure graphite bipolar plate for Proton Exchange Membrane Fuel Cells (PEMFC). PCBP can reduce the weight and volume occupied by PEMFC assembly, enhancing the payload capacity of hydrogen-powered electric vehicles. This study focuses on the development of PCBP using Multi-Walled Carbon Nanotube (MWCNT) as tertiary filler, Carbon Black (CB) as secondary filler, Natural Flake Graphite (NFG) as primary filler and bisphenol A Epoxy resin (EPR) as binder. The fabrication is done by compression molding. The study aims to examine the effect of filler concentration of MWCNT on the mechanical, electrical, morphological, chemical and thermal properties of the PCBP. The optimized PCBP with 3.0 vol% MWCNT achieved a flexural strength of 46 MPa, in-plane electrical conductivity of 182 S cm−1 and a corrosion current density of 0.221 μA cm−2, satisfying 2025 US Department of Energy targets. Additionally, it demonstrated a bulk density of 1.46 g cm−3, shore D hardness of 70, thermal conductivity of 5.45 W mK−1 and a water contact angle of 86.78°, which are desirable values for PEMFC application. These results underline the potential of hybrid nanocomposite PCBPs to enhance the desired properties of PEMFC systems, paving the way for advancements in hydrogen fuel cell vehicles.

Utralow coefficient of thermal expansion in a spheroidized natural flake graphite based isotropic graphite

Utralow coefficient of thermal expansion in a spheroidized natural flake graphite based isotropic graphite

A Multifunctional Surface Modifier Capable of Stabilizing 5.0 V Graphite Cathode via Reinforced Mechanical Strength and Preferential Anion Adsorption

AbstractWith the ever‐increasing demand for high power and high energy batteries, extensive researches devote to high voltage cathode materials. Graphite cathode‐based dual‐ion batteries (DIBs) possess the unique advantages of high working voltage (≈4.5−5.0) and high power, but still suffer from low coulombic efficiency and poor long‐term stability mainly resulted by the serious oxidative decomposition of electrolytes and significant structural deterioration of graphite cathode. From the perspectives of simultaneously reinforcing the mechanical strength of graphite cathode and suppressing the decomposition of electrolytes via a cathode/electrolyte interphase (CEI), polyacrylic acid (PAA) is adopted as the surface modifier of natural graphite (NG). The mechanical stability of graphite cathode is significantly improved by virtue of the bonding interaction between PAA and binder, which is validated through both theoretical calculation and experimental observation. In addition, PAA contributes to the formation of a LiF‐rich and homogeneous CEI through the preferential adsorption of anions, and effectively mitigates the cointercalation and decomposition of solvent. As the cathode material of DIBs, NG@PAA manifests fast charge/discharge capability and outstanding capacity retention of 73.9% after 8000 cycles. This work provides a surface modification strategy for optimizing the performance of electrode materials from multiple perspectives.

Microwave-Assisted Green Synthesis of Fluorescent Graphene Quantum Dots: Metal Sensing, Antioxidant Properties, and Biocompatibility Insights.

Graphene quantum dots (GQDs) are highly valued for their chemical stability, tunable size, and biocompatibility. Utilizing green chemistry, a microwave-assisted synthesis method was employed to produce water-soluble GQDs from Mangifera Indica leaf extract. This approach is efficient, cost-effective, and environmentally friendly, offering reduced reaction times, energy consumption, and uniform particle sizes, and has proven advantageous over other methods. Water-soluble GQDs were synthesized using Mangifera Indica leaf extract, which ranged less than 15nm in diameter, confirmed by high-resolution transmission electron microscopy with a lattice spacing of 0.34nm. The GQDs exhibited strong photoluminescence with bright red fluorescence under UV light and excitation-independent emission at 662nm with excitation wavelengths ranging from 300 to 500nm, achieving a quantum yield of 10.3%. A peak at 27.2˚ was recorded corresponding to the graphite's (002) plane diffraction peak. Raman spectroscopy confirmed their graphitic nature and sp2 crystallinity, with an intensity ratio of D and G peak ID/IG ratio of 1.12. Biocompatibility assays (MTT and live/dead) showed better results at lower concentrations (1mg/ml) while higher concentrations (2mg/ml) showed reduced efficacy. Antioxidant tests revealed increased DPPH scavenging activity with higher GQD concentrations and longer incubation times. The GQDs demonstrated excellent performance as fluorescent biosensors for Ni2⁺ (0.15ppm) and Fe3⁺ (0.20ppm), with high selectivity in river water samples, highlighting their potential for environmental and health applications.

High Pressure Hydrothermal Purification of Natural Flake Graphite Based on Response Surface Methodology

High Pressure Hydrothermal Purification of Natural Flake Graphite Based on Response Surface Methodology

Studies of Thermal Conductivity of Graphite Foil-Based Composite Materials.

We have proposed and developed a method for measuring the thermal conductivity of highly efficient thermal conductors. The measurement method was tested on pure metals with high thermal conductivity coefficients: aluminum (99.999 wt.% Al) and copper (99.990 wt.% Cu). It was demonstrated that their thermal conductivities at a temperature of T = 22 ± 1 °C were <λAl> = 243 ± 3 W/m·K and <λCu> = 405 ± 4 W/m·K, which was in good agreement with values reported in the literature. Artificial graphite (ρG1 = 1.8 g/cm3) and natural graphite (ρG2 = 1.7 g/cm3) were used as reference carbon materials; the measured thermal conductivities were <λG1> = 87 ± 1 W/m·K and <λG2> = 145 ± 3 W/m·K, respectively. It is well established that measuring the thermal conductivity coefficient of thin flexible graphite foils is a complex metrological task. We have proposed to manufacture a solid rectangular sample formed by alternating layers of thin graphite foils connected by layers of ultra-thin polyethylene films. Computer modelling showed that, for equal thermal conductivities of solid products made of compacted thermally exfoliated graphite and products made of a composite material consisting of 100 layers of thin graphite foil and 99 layers of polyethylene, the differences in temperature fields did not exceed 1%. The obtained result substantiates our proposed approach to measuring thermal conductivity of flexible graphite foil by creating a multi-layer composite material. The thermal conductivity coefficient of such a composite at room temperature was <λGF> = 184 ± 6 W/m·K, which aligns well with measurements by the laser flash method.

Toward Fast-Charging and Dendritic-Free Li Growth on Natural Graphite Through Intercalation/Conversion on MoS2 Nanosheets.

During fast-charging, uneven lithium plating on the surface of commercial graphite anode impedes the electrochemical performance of lithium-ion batteries, causing a safety issue. The formation of a passivation layer, the solid-electrolyte interphase (SEI), due to side reactions with the organic electrolyte, correlates with long-term cycling performance under fast-charging conditions, necessitating comprehensive analysis. Herein, it is demonstrated that a molybdenum disulfide (MoS2) coating on natural graphite (NG) modulates the properties of the SEI layer, enabling reduction of the charging time and the enhancement of long-term cycling performance. MoS2 spontaneously transforms into Li2S and Mo nanoclusters through intercalation and conversion with Li+, altering the chemical composition and stability of the SEI layer on the NG, promoting faster Li+ transport, and reducing interfacial resistance. The MoS2-NG anode shows improved fast-charging capability and cycling performance under 3.0 C-charging and 1.0 C-discharging over 300 cycles without compromising energy density. In the full-cell configuration, a charging time of 14.7 min at 80% state of charge is achieved, making it suitable for electric vehicle applications.

Mitigating the Effect of High Overpotential during Al Deposition on Aluminium‐Graphite Battery Performance

This study investigates the impact of current density on electrode potential during aluminium (Al) dissolution/deposition step from/on an Al foil as well as the charge‐discharge behaviour of aluminium‐graphite batteries (AGB) in various AlCl3‐based electrolytes. Experiments in a cell with graphite blocking electrodes evidenced higher chemical stability of 1:1.5 Urea:AlCl3 electrolyte, followed by TEA:AlCl3 and EMIMCl:AlCl3. In Al‐Al symmetric cells, current densities above 1 mA cm−2 led to a notable rise in overpotential up to 100 mV during Al deposition in both TEA:AlCl3 and Urea:AlCl3 electrolytes mostly due to low surface area of native Al foil. Higher overpotentials during Al deposition caused ‘incomplete’ AlCl4¯ intercalation in natural graphite, resulting in capacity fade at current densities between 0.5 and 5 A g‐1. By adjusting upper cut‐off voltage during charging step as a function of applied current value according chemical electrolyte stability, significant improvement in specific capacity and energy density was achieved during discharging step. For instance at 1 A g‐1, the specific energy density of AGB increased by 10% in EMIMCl:AlCl3, 48% in TEA:AlCl3, and an impressive 250% in Urea:AlCl3.During long‐term cycling post‐UCV adjustment, the capacities of AGB increased by 10%, 13%, and 27% for AGBs with EMIMCl:AlCl3, TEA:AlCl3 and Urea:AlCl3, respectively.

Impact of diffusion layer structure of air electrodes on their performance in neutral zinc/iron - air batteries

Impact of diffusion layer structure of air electrodes on their performance in neutral zinc/iron - air batteries

Construction of a waste-derived graphite electrode integrated IL/Ni-MOF flowers/Co3O4 NDs for specific enrichment and signal amplification to detect aspartame

Construction of a waste-derived graphite electrode integrated IL/Ni-MOF flowers/Co3O4 NDs for specific enrichment and signal amplification to detect aspartame

A Dilatometric Study of Natural Graphite Anode for Li Ion Battery

A Dilatometric Study of Natural Graphite Anode for Li Ion Battery

Advance Development in Natural Graphite Material and Its Applications: A Review

Advance Development in Natural Graphite Material and Its Applications: A Review

Preparation, Characterization and Application of Sustainable Composite Phase Change Material: A Mineral Material Science Comprehensive Experiment

Phase change materials (PCMs) play a significant role in achieving sustainable objectives for green buildings. Organic solid–liquid PCMs have excellent heat energy storage density and suitable working temperatures, making them a focal point of research attention. However, these materials face challenges such as potential leakage, low thermal conductivity, and limited fire resistance, which hinder their direct application in the construction industry. Therefore, mineral-based PCMs are highly regarded due to their safety features, environmental friendliness, non-toxicity, and cost-effectiveness within sustainable building development. In this work, a multistage porous kaolinite-based geopolymer encapsulation material using primary raw materials like kaolinite mineral, sodium silicate surfactants, and hydrogen peroxide was successfully synthesized. The PEG is used as the organic solid–liquid PCM while natural graphite mineral serves as a heat transfer enhancement agent to fabricate a novel and sustainable mineral-based composite PCM, which could be applied at the environment temperature from 35–60 °C approximately. Furthermore, a study on material properties was conducted to investigate influencing factors. Comprehensive experimental reform on mineral-based PCMs will offer proficiency in experimental operations and foster the talents’ capacity for comprehensive design, which holds immense significance for understanding and designing mineral materials. This work holds great significance for the sustainable development for education and green buildings.

Application of high-speed hydrodynamic technology for the production of graphene nanosuspensions from natural graphites

Carbon nanostructures have been in the focus of world science for more than 25 years, since the discovery of fullerenes in 1985, single-walled carbon nanotubes in 1993, graphene in 2004, graphene quantum dots in 2004. Graphene is a monocrystalline graphite films (2D material) with a thickness of several atoms that are stable under environmental conditions and they have excellent electronic, mechanical, chemical, thermal and optical properties. All over the world, research and development of new methods of using graphene in various fields such as energy, oil production, materials science, and electronics are actively carried out. Currently, the use of graphene-containing materials as modifiers for the creation of durable and effortless materials in aviation, automotive and other branches of engineering is an urgent problem. It is advisable to introduce graphene particles into the composition of composite materials using their stable dispersions in a liquid medium. The production of colloidal graphene suspensions is effective in many cases using the method of liquid phase exfoliation of graphite. The paper presents the results of studying the physico-chemical properties of aqueous graphene suspensions obtained by liquid-phase exfoliation of natural graphites using high-speed hydrodynamic technology. Graphite grades GK-1 and GAK-2 (Grafitservice, Chelyabinsk, Russia) are crystalline graphites obtained by enrichment of graphite ores and joint enrichment of natural graphite ores and graphite-containing waste from metallurgical industries, respectively. Graphite suspensions were prepared in distilled water with 1 wt.% graphite, surfactant was added to some samples, processing time (3–120 min), rotor rotation speed (4 000–11 000 rpm). The resulting graphene suspensions were investigated by XRD, by electron microscopy and sedimentation analysis methods. The particle size was determined using the DT-1202 electroacoustic spectrometer. The presence of multilayer graphene is confirmed by comparing the results of XRD with the literature data. Along with multilayer graphene, the presence of graphene dots was detected. Aqueous graphene suspensions for graphites with different sedimentation times have been obtained. For graphite GAK-2 – six days, for graphite GK-1 – 90 days, for graphite GK-1 + surfactant – 6 months.

Synthesis of Ultra-Large Diameter Graphene Oxide Flakes from Natural Flake Graphite

Synthesis of Ultra-Large Diameter Graphene Oxide Flakes from Natural Flake Graphite

A study on the change of maceral components in the natural graphitization process of coal

A study on the change of maceral components in the natural graphitization process of coal