Synthetic Graphite Research Articles

Manufacturing Scale-up of ALD Onto Synthetic Graphite Powder in a Continuous Vibrating Reactor for Battery Applications

As the demand for improved performance in battery material increases, development of large-scale, high-throughput ALD processes and equipment is necessary to meet production demands. Forge Nano has previously demonstrated ALD deposition onto natural and synthetic graphite over a range of scales (50 g – 50 kg) in both rotary bed and fluidized bed reactors. This process has now been successfully scaled-up to the highest throughput system (ton scale) with a continuous vibrating reactor (CVR). The CVR (and associated product Circe) is a spatial ALD system where the substrate powder travels down a porous deck, driven by vibration. Process gases flow at atmospheric pressure perpendicularly to the powder flow, up through the porous deck, and fluidize the moving powder bed and mixing the particles with the gases top to bottom in the process. The substrate travels through zones of the precursors and purge gases of an ALD cycle (Figure 1).Reproducibility per batch and relative to successful graphite deposition criteria from smaller ALD batch systems was explored in a CVR system configured to perform 4 TMA/H2O ALD cycles. Commercial synthetic graphite was coated at a rate of 33 kg/h, in 45-50 kg batches, at 180°C. Precursor flow was controlled based on the calculated stoichiometry required to achieve 100% titration of available surface sites, as determined in experiments performed in small scale fluidized bed reactors. Samples of coated product were taken from the reactor effluent every 10 minutes. Effluent samples of replicate runs were analyzed using ICP to determine the Al loading, and to characterize the reproducibility of the coating process. An average of 84 ± 13 ppm Al was deposited for all replicate runs (each totaling 4 ALD cycles). The 1-2 initial samples for a given run comprised lower Al mass loadings, likely due to the system approaching steady state in terms of substrate and precursor flow. Additional tests with 150% of the calculated stoichiometric TMA flow rate showed the deposition to be self-limiting. Finally, the coated material was homogenized and then recycled through the CVR to demonstrate reproducibility at higher deposition levels. This material was recycled multiple times to achieve 20 TMA/H2O ALD cycles and establish an average and linear growth rate per ALD cycle. Additionally, bed height and speed conditions were explored to achieve higher material processing rates. Coated materials were tested in coin cells as anode powders for lithium-ion batteries, with performance being compared to coated graphite prepared via more traditional deposition in fluidized bed reactors under vacuum conditions. Coated materials demonstrated that increasing coating levels increased first cycle coulombic efficiency (FCE), reversible capacity, and cycle life.Figure 1. Schematic and photo of the spatial CVR ALD system Figure 1

Synthetic Graphites as the Cathode Material for Aluminium-Carbon Batteries

Developments such as growth in electric vehicle production and increased use of renewable energy sources, has caused an exponential increase in the demand for batteries [1,2], with Li-ion batteries as the dominating technology. Various issues are associated with the materials of Li-ion batteries, like an uncertainty about the future access, environmental footprint and social impact related to raw materials extraction and production, as well as the challenge of recycling [3]. For this reason, there is a renewed interest in alternative battery chemistries, and one candidate technology is the Aluminium-Carbon (Al-C) battery. This is a so-called dual-ion concept, with an Al anode, a carbon (mostly graphite) cathode, and an electrolyte based on Al salts. During charging, anions intercalate into the graphite, while Al deposits on the anode [4]. Al has a high theoretical volumetric and gravimetric capacity, in addition to being abundant [5]. Like graphite, it is also a low-cost material [4,5], so using these together can provide an affordable battery technology. In addition, these batteries would be very convenient to recycle due to the mature, worldwide recycling infrastructure of Al [6] combined with the fact that graphite can withstand high temperature treatment [7]. The most commonly used electrolyte is AlCl3 in 1-Ethyl-3-methylimidazolium chloride (EMIMCl), which is a thermally stable ionic liquid [8]. It also has a high ionic conductivity [8], allowing high currents and subsequently high-power batteries, but it has the drawback of being highly corrosive [9]. Alternative electrolytes are aluminium trifluoromethanesulfonate (Al(OTF)3) or aluminium bis(trifluoromethanesulfonyl)imide (Al(TFSI)3) and LiAlH4 in tetrahydrofuran (THF), which eliminates the corrosion issue. With Al(OTF)3 as the main salt, it has been shown to reversibly plate Al [10]. However, to the best of our knowledge such electrolytes are not used in Al-C batteries to this date.Work on Al-C batteries have been conducted with a wide range of carbons (e.g. natural and synthetic graphites or fibrous carbon materials), and it has been shown that a high degree of crystalline perfection and flake-shaped particles are preferred for high capacity [4,11]. Capacities obtained when using graphite powders are in the range between 60 and 142 mAh/g, depending on their characteristics [4]. Al-C batteries can also have excellent rate capabilities, as observed in the work of Wu et al. [12] where a 3D graphitic foam gave a stable capacity around 60 mAh/g for 4000 cycles at the high rate of 12 A/g. However, carbon materials for which outstanding results are reported, are not always commercially available. Al-C batteries are still at an early stage of development, and knowledge related to graphite properties and how these affect stability at high voltages, and intercalation of anions from the relevant electrolytes is still limited.In this work, we have studied industrially relevant synthetic graphites as cathodes for Al-C batteries, with the purpose of investigating the anion intercalation and oxidation stability with respect to graphite properties, like surface area, surface structure (edge, basal and defect sites), and surface chemistry. Graphite powders have been investigated by nitrogen adsorption, LECO oxygen analysis and XRD measurements in order to determine the relevant properties. The electrolytes used are AlCl3 in EMIMCl, and Al(OTF)3 as well as Al(TFSI)3 with LiAlH4 in THF. To provide further information about the reactions happening during cycling, post-mortem characterization of cycled electrodes with SEM, AFM, FTIR and Raman spectroscopy is carried out. In this manner it can be investigated if the reactions occurring is the wanted reversible intercalation, or if irreversible reactions at the electrode surface also take place.This project has received funding from The Research Council of Norway: Contract number 331964. Partners in the project are NTNU, SINTEF Industry, Vianode, Beyonder and Equinor ASA.

Unraveling the Sequential Effect of Dual-Layered Hybrid Graphite Anodes on Electrode Utilization during Fast-Charging Li-Ion Batteries

The efficient and fast recharging of Li-ion batteries without compromising capacity or safety is paramount in advancing energy storage technologies. This study addresses this challenge by developing a novel electrode design known as dual-layer electrode (DLE) technology, achieved via a carefully orchestrated sequential coating process involving two distinct anode materials. The primary objective is to minimize cell polarization, a critical factor impacting charging efficiency and battery longevity, particularly at higher charging currents.The research employs advanced electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis to delve into the dynamic evolution of electrode impedances. Notably, synthetic graphite (SG) exhibits varying impedance characteristics with changes in the state of charge (SOC), contrasting with the relatively stable impedance observed in natural graphite (NG) across SOC variations. This fundamental difference is a critical determinant in arranging NG and SG layers within the DLE, strategically considering the temporal SOC gradient encountered during fast charging cycles.The study leverages simulation models alongside experimental validation to ascertain the optimal positioning of NG and SG layers within the DLE structure. The results demonstrate that placing NG atop SG in the DLE configuration significantly reduces overall resistance, leading to remarkable performance gains. Specifically, the DLE exhibits a remarkable 61.0% capacity retention over 200 cycles when charged at a 4 C rate (equivalent to a 15-minute charging duration). This performance surpasses counterparts with reversed sequential coating and even outperforms single-layer electrodes utilizing either NG or NG/SG mixed electrodes.Furthermore, this research contributes valuable insights into the combinatorial sequence for multi-layer coating of various active materials, particularly in thick-electrode designs. The findings hold significant implications for advancing the development of high-performance Li-ion batteries tailored for fast-charging applications across diverse sectors by achieving lower resistivity and enhanced charging efficiency.

An Electrochemically Promoted Approach to Graphitization Via Molten Salts

Graphite stands as a critical element, as recognized by the US Department of Energy, owing to its pivotal role as anodes in batteries. The demand for high-purity graphite in battery applications is poised to surge in the foreseeable future. Synthetic graphite, prized for its high purity, typically emerges as the preferred option for such applications. However, the current synthesis process for graphite is exceedingly energy-intensive, mandating heat treatment of carbon precursors at temperatures soaring up to 3300 K for successful graphitization. In this talk, a novel method for graphitization is presented, one that operates at significantly lower temperatures and harnesses an electrochemical approach. Through cathodic electrochemical polarization of amorphous carbon in molten salts, the transformation of amorphous carbon into a highly graphitic structure is achieved. This innovative process holds promise in conserving substantial energy compared to existing methodologies.

Simultaneous Entropic Coefficient Measurement and Multi-Species, Multi-Reaction Modelling

The multi-species, multi-reaction (MSMR) model is developed through the fitting of pseudo-open circuit voltage (POCV) data acquired by cycling a cell at a sufficiently low rate (C/50).1 By comparing MSMR fitted data taken at various temperatures, both temperature dependence of fitting parameters and thermodynamic data including the state-of-charge (SOC) dependent entropic coefficient (dU/dT), entropy (ΔS), and enthalpy (ΔH) can be gleaned.2 In this presentation, POCV behavior of coal-derived graphite will be discussed and compared to thermodynamic measurements of lithium-intercalation under potentiostatic testing conditions.3 Simultaneously measuring POCV data and determining thermodynamic parameters has the advantages of minimizing testing time and complexity. The MSMR model’s ability to distinguish minute changes in temperature dependent active material behavior will be highlighted through a comparison of coal-derived graphite and commercially available synthetic graphite.4 Implications of thermodynamic parameters and temperature dependent behavior on cell and pack level engineering will also be presented.

Coal-Derived Nanoscale Materials for Energy Storage Applications

The demand for carbon-based energy storage materials is growing as renewable energy production and electrification expand worldwide. The types of carbon-based energy storage materials are as diverse as the systems in which they operate. The source of these materials is also of interest. Some carbon-based energy storage materials are naturally occurring (i.e., graphite) while others are synthesized from other carbon precursors (i.e., synthetic graphite, activated carbon, graphene, etc.). This presentation will focus on this group's efforts to synthesize, by electrochemical methods, nanoscale carbon materials from an abundant natural resource, coal. The electrochemical synthesis procedure and physical characterization of the nanoscale materials will be discussed. The nanoscale material's performance in energy storage systems will be presented and compared to other commercially available carbon-based energy storage materials.

Hydrodynamic Jet Cavitation to Process Natural Graphite for Ultra-Fast Charging Lfp // Graphite Pouch Cells

Graphite has proven to be the most dominant anode material for Li-ion batteries (LIBs) due to its relatively high gravimetric capacity (372 mAh g-1), high Li-ion diffusion coefficient (~10-11 cm2 s-1) andlow delithiation potential (0.1V vs. Li/Li+). (1) Current methods of producing battery-grade graphite are both energy and greenhouse gas intensive. (2) New methods of processing graphite with far lower carbon footprints are becoming available using hydrodynamic jet cavitation. (3) This work tests the Li ion battery anode performance of three different jet cavitation processed graphite powders that have been processed by the above-mentioned method. The materials both matched the performance of commercial synthetic graphite anodes in low C-rate cycling and showed an improved capacity of >100 mAhg-1 LFP in full cells at 10C. Additional testing was also performed on single layer pouch cells. It was found that the rougher surface morphology of the jet cavitation processed graphite causes a slightly poorer initial coulombic efficiency but a far greater capacity at high C-rates.

Aging and Power Characterization of Graphite-NMC Cells Containing Coal-Derived Graphites

Virtual scale-up of battery cell and pack designs requires detailed information about the thermodynamics and kinetics of lithium storage and transport in the active materials. To investigate lithium transport and kinetics in coal-derived graphites, pouch cells containing three coal-derived anode materials and one control synthetic graphite were prepared and tested with a reference performance test (RPT) followed by hybrid pulse power characterization (HPPC) every 50th cycle. The RPT, performed at a slow rate (C/50) yields pseudo-open circuit voltage behavior that is used to study changes in active material storage mechanisms by comparing to the initial behavior through the lens of the multi-species, multi-reaction (MSMR) model.1,2 HPPC testing at various state-of-charge (SOC) measures the transient resistance and is used to extract kinetic and diffusion parameters.A comparative study between the three developed coal-derived anode materials will be presented with emphasis on enabling virtual scale-up and studying potential degradation pathways. The overarching goal of this work is to develop a workflow for validating alternative graphite materials to address graphite supply chain issues for applications in electric vehicles and grid storage.

Effect of Mechanically Exfoliated Graphite Flakes on Morphological, Mechanical, and Thermal Properties of Epoxy

Carbon-reinforced polymer composites form an important category of advanced materials, and there is an increasing demand to enhance their performance using more convenient and scalable processes at low costs. In the present study, graphitic flakes were prepared by the mechanical exfoliation of synthetic graphite electrodes and utilized as an abundant and potentially low-cost filler to fabricate epoxy-based composites with different additive ratios of 1–10 wt.%. The morphological, structural, thermal, and mechanical properties of these composites were investigated. It was found that the thermal conductivity of the composites increases by adding graphite, and this increase mainly depends on the ratio of the graphite additive. The addition of graphite was found to have a diverse effect on the mechanical properties of the composites: the tensile strength of the composites decreases with the addition of graphite, whilst their compressive strength and elastic modulus are enhanced. The results demonstrate that incorporating 5 wt% of commercially available graphite into epoxy not only raises the thermal conductivity of the material from 0.223 to 0.485 W/m·K, but also enhances its compressive strength from 66 MPa to 72 MPa. The diverse influence of graphite provides opportunities to prepare epoxy composites with desirable properties for different applications.

Tailored graphene nanoparticles for biomedical application: preliminary in vitro characterization of the functionality in model cell lines

Thanks to an environmentally friendly physical treatment of high purity graphite, a good control of the structure of graphene nanoparticles (GNPs) has been obtained with the production of stable and reproducible GNPs water dispersions. The preparation protocol entailed ball-milling of synthetic graphite followed by sonication in water and centrifugation/separation procedures. This way, two different GNPs samples with slightly different structural characteristics were harvested: TOP60, showing an average lateral size of the graphene layers <L> = 70 nm and average number of stacked layers <N> = 4, and BOTTOM60, with <L> = 120 nm and <N> = 6. A detailed structural characterization of GNPs was performed as mandatory pre-requisite to build reliable structure/properties correlations, in terms of both biomedical efficacy and toxicity, aiming at a rationale design of tailored materials for applications in biological environments.To this end, in this study GNPs were thoroughly characterized, focusing on cytotoxicity, cellular uptake, and inflammatory response, by testing their effect in different cell lines. BOTTOM60 GNPs in culture medium and in the presence of cells showed a tendency to form big aggregates, phenomenon that was probably responsible for their cytotoxicity at high concentrations. On the other hand, TOP60 GNPs showed a diverse behavior depending on the cell type under investigation. Indeed, the nanoparticles were internalized by cells specialized in endo/phagocytosis, such as astrocytoma cells, but not by carcinoma cells of epithelial origin. Moreover, TOP60 GNPs caused a reduction of proliferation only at high concentration and did not trigger an inflammatory response in THP-1-derived macrophages.The evidence here collected paves the way for further investigations towards the development of GNPs-based drug delivery systems.

Birla Carbon plans US synthetic graphite plant

Birla Carbon plans US synthetic graphite plant

The Effect of Fractional Composition on the Graphite Matrices' Porosity.

Synthetic graphite of complex fractional composition was mixed with phenolic resin as a binder and pore-forming component. The mixtures were pressed and subsequently heat-treated to obtain porous matrices. The structural transformations of phenolic resin by heating up to 900 °C in oxygen and inert gas media were studied and the patterns of amorphization of fixed carbon formed on the walls of the pore system during carbonization were investigated. We found regularities in the changes in matrix volume density in the function of the open porosity and the average pore diameter. It is shown that, in order to obtain graphitized carbon matrices with a density of 1 g/cm3 and an open porosity of at least 50%, it is necessary to introduce no more than 20% of phenolic resin into the molding powder with an equal content of 60, 100 and 250 μm graphite fractions. This allows for high intensity and completeness of bulk silicon infiltration.

Production of Low Temperature Synthetic Graphite

Synthetic graphite is a material consisting of graphitic carbon which has been obtained by graphitizing a non-graphitic carbon. The growth in demand, particularly in customizing properties for certain usage has brought about research on viable alternative, low-cost, and environmentally pleasant synthetic graphite production. Biomass wastes are amongst appealing carbon precursors which have been broadly checked out as replacement carbon for graphite production. This research aimed to synthesize synthetic graphite from oil palm trunks at low temperatures (500 °C, 400 °C and 300 °C) under controlled conditions to determine the physical properties and properties of the graphite obtained. After the heat treatment process, the obtained samples were then characterized by using XRD, SEM and RAMAN characterizations. Based on SEM and RAMAN characterization, it can be seen that graphite that undergoes a 500 °C pyrolysis process shows the best results compare to graphite that undergoes a pyrolysis process at the temperatures of 300 °C and 400 °C. The graphite flakes and the peaks obtained for 500 °C graphite are obviously present. For XRD characterization, the best samples at 500 °C were chosen to be characterized. From the results, the sample shows slight behavior imitating the commercialized graphite. Hence, from the characterizations of the samples, it can be concluded that the best synthetic graphite produced was from the oil palm trunks heated at 500 ° C.

Sustainable Production of Biomass-Derived Graphite and Graphene Conductive Inks from Biochar.

Graphite is a commonly used raw material across many industries and the demand for high-quality graphite has been increasing in recent years, especially as a primary component for lithium-ion batteries. However, graphite production is currently limited by production shortages, uneven geographical distribution, and significant environmental impacts incurred from conventional processing. Here, an efficient method of synthesizing biomass-derived graphite from biochar is presented as a sustainable alternative to natural and synthetic graphite. The resulting bio-graphite equals or exceeds quantitative quality metrics of spheroidized natural graphite, achieving a Raman ID/IG ratio of 0.051 and crystallite size parallel to the graphene layers (La) of 2.08 µm. This bio-graphite is directly applied as a raw input to liquid-phase exfoliation of graphene for the scalable production of conductive inks. The spin-coated films from the bio-graphene ink exhibit the highest conductivity among all biomass-derived graphene or carbon materials, reaching 3.58 ± 0.16 × 104 Sm-1. Life cycle assessment demonstrates that this bio-graphite requires less fossil fuel and produces reduced greenhouse gas emissions compared to incumbent methods for natural, synthesized, and other bio-derived graphitic materials. This work thus offers a sustainable, locally adaptable solution for producing state-of-the-art graphite that is suitable for bio-graphene and other high-value products.

Effect of Mixing Methods and Black Conductive Fillers on Properties of Natural Rubber Composites

Carbon black, graphite, carbon nanofibers, carbon nanotubes, and metal fillers increase composite conductivity in natural rubber, which is electrically insulating. Depending on dispersion, conductive filler lowers insulating material resistivity. These materials are frequently used for electromagnetic/radio frequency interference (EMI/RFI) shielding, conductive flexible seals gaskets, and conductive mats used to prevent electrostatic damage to electronic devices. These elastomers could be used to make flexible solar cells or mechanical-to-electricity devices. Temperature, mixing time, shear rate, and cross-linking during vulcanization affect rubber electrical conductivity of composite. To study shear rate effects, vulcanizate of Natural Rubber-based composites filled with carbon black, millable carbon fiber powder, and synthetic graphite powder was prepared by open mixing (two roll mill) and close mixing (internal mixer). We compared how shear rate affects cure, stress-strain, and volume resistivity of conductive filler-based Natural Rubber composites. Increment in clearance of two roll mill during addition of rubber additives along with rubber of reduced the shearing force resulted in less dispersive and distributive mixing and stagnant points due to band formation on roll surface compared to intermix where compound movement had no stagnation point and long wings pushed material axially and two nogs pushed material in other chamber. Compared to two roll mill samples, the compound reached every point of the mixing chamber for best homogeneity, reducing cure time and improving stress-strain and volume resistivity.

Solar still basin measurements and liner material variance for improved water desalination efficiency

Access to potable water remains a global challenge, and solar stills offer a sustainable desalination solution. Solar stills however have low desalination efficiencies. The impact of basin measurements and liner material variance on their performance have not been evaluated, and this study sought to investigate this through modelling with the objective of improving the performance of a one-slope solar still. MATLAB is employed in the model development and simulations. The developed model is validated using other experiments in literature. The analysis is done with Machakos (1.52°N, 37.2°E), Kenya climatic conditions as a reference. Various basin liner materials including aluminium, synthetic graphite, brass, galvanized iron and stainless steel are examined based on their thermal properties. Different width-to-length ratios ranging from 0.14 to 0.86 are investigated. Basin liner thicknesses of between 2 mm and 6 mm are evaluated. A parametric study is conducted to determine the correlation between liner material thickness and basin dimensions, and their combined impact on freshwater yields. From the results, synthetic graphite had the best performance, followed by aluminium, brass, galvanized iron and stainless steel with efficiencies of 35.04 %, 24.02 %, 17.02 %, 14.13 % and 12.39 %, respectively. Thus, synthetic graphite outperformed aluminium, brass, galvanized iron and stainless steel by 31.4 %, 51.43 %, 59.675 % and 64.64 %, respectively. A width-to-length ratio of 0.45 yields optimal results, while a liner material thickness of 4 mm is found to be ideal across all materials. The parametric study further reveals that width-to-length ratio has a higher significance on freshwater yields compared to liner material thickness.

Temperature-dependent evolution of synthetic coal-derived graphite fillers and their reinforcement in styrene butadiene rubber composites

This study investigated the structural evolution of synthetic coal-derived graphite (SCG), produced from anthracite through high-temperature treatments ranging from 1000 to 2900 °C, and its reinforcement potential in styrene butadiene rubber (SBR) composites. Upon heating the anthracite to 2000 °C, We observed a gradual structural transformation from an amorphous carbon structure with mixed sp2-sp3 bonding to an ordered sp2-bonded nano-sized graphitic structure. This transformation was accompanied by the evaporation of heteroatom functional groups, an increase in high surface energy site as well as micropore and void structures, and enhanced hydrophobic surface property. Beyond 2000 °C, a flake-like graphite with a larger particle size (average lateral size >10 μm) was gradually formed through lateral and vertical crystalline growth mechanisms. The reinforcing potential of SCG fillers was revealed by incorporating them into SBR and evaluating the properties of the resulting composites. It was found that the tensile strength and 300 % tensile modulus initially enhanced with SCG fillers treated up to 2000 °C, but decreased for fillers treated at 2300 and 2900 °C. On the other hand, storage modulus, tear resistance, and gas permeability consistently improved with fillers treated at higher temperatures. These findings highlight the relationship between the temperature-induced structural evolution of SCG fillers and their reinforcement performance in SBR composites, offering valuable insights for industrial rubber applications, particularly enhancing the performance and sustainability of automotive tire.

Increasing the Thermal Resistance of Water-Based Mud for Drilling Geothermal Wells

Energy demand and growing environmental concerns have fueled increased interest in geothermal drilling in recent decades. The high temperature and pressure in the boreholes present significant challenges to drilling, particularly in terms of the selection of suitable drilling mud, cement slurry, and drilling equipment. Drilling mud is regarded as one of the primary factors that affect the cost and success of geothermal drilling. This paper presents experimental studies aimed at assessing the thermal stability of drilling muds for geothermal drilling. Research on the antidegradation of polymers contained in drilling muds is presented. The thermal stability of drilling fluids was evaluated on the basis of changes in rheological and filtration parameters under the influence of a temperature of 160 °C. Attempts were made to increase the thermal resistance of drilling fluids by using antioxidants and glycol compounds. The effectiveness of increasing the thermal resistance of muds by adding synthetic polymers, nanomaterials, and graphite was tested. A new way of increasing the thermal resistance of drilling muds by using fatty amine compounds in combination with the amine agent ‘TEA’ was proposed. Tests showed that the addition of polyglycol and the antioxidant agent sodium ascorbate to the mud did not protect the polymers from decomposition at 160 °C. There was no effect of increasing the thermal conductivity on improving the thermal resistance of the scrubber. Based on the analysis of results from laboratory tests, a composition of a water-based drilling mud without bentonite was developed for drilling geothermal wells. The developed drilling mud is characterized by thermal resistance up to 160 °C, stable rheological parameters, low filtration, and appropriate thermal conductivity characteristics.

Graphene oxide with different oxygen content produced from natural and synthetic graphite sources for methylene blue sorption

Graphene oxide (GO) is of great interest due to its unique structure and properties and potential applications, including water purification. In this work, we report the synthesis of GO samples with different oxidation degree from two different sources of graphite using Hummers method. Natural flake graphite with a high degree of crystallinity, and synthetic fine powder graphite were used. All produced materials were characterized by CHNS analysis, X-Ray Diffractive analysis (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). It was shown that the oxidation process for natural and synthetic graphite sources proceeds in different ways. The factors, affecting for the structure and properties of GO are the degree of crystallinity and the lateral size of the graphite flakes. The sorption activity of underoxidized, normally oxidized and overoxidized GO was compared toward the methylene blue (MB) dye in aqueous solution. The most efficient sorption was registered for GO produced from synthetic graphite with the use of 2.0 and 4.5 wt. eq. KMnO4. The sorbents removed 94 % and 100 % of MB from the solution, respectively, in approximately 10 min. Our results reveal that the structure and sorption properties of GO can be tuned by varying the oxidation degree as well as the graphite source, which may open the way to new developments in the GO-based materials applications.

Characterization and Analysis of Coal-Derived Graphite for Lithium-Ion Batteries

Graphite is a critical material used as the negative electrode in lithium-ion batteries. Both natural and synthetic graphites are utilized, with the latter obtained from a range of carbon raw materials. In this work, efforts to synthesize graphite from coal as a domestic feedstock for synthetic graphite are reported. The performance in lithium-ion coin cells of this coal derived graphite is compared to commercial battery-grade graphite. This includes characterization of the thermodynamics of the coal derived graphite using the multi-species, multi-reaction (MSMR) model, characterization of the entropy and enthalpy of the material, and estimation of the rate capability. This enables modeling of synthetic coal-derived graphites and virtual evaluation[1] of these materials towards electric vehicle and grid storage applications.