Synthetic Graphite Research Articles

Ionic Liquids Based Cocktails as a Composite Redox Electrolyte for Natural Dye-Sensitized Solar Cells

Fatty-imidazolinium electrolytes, waste graphite dispersed composite electrolytes like cocktails (1,3-methyl octyl-1,2,3-benzotiazolium acetate–cis-oleyl-imidazolinium iodide), and graphite exfoliation using cis-oleyl-imidazolinium acetate have been studied to enhance the efficiency of a newly developing dye-sensitized solar cells (DSSCs). The DSSCs were fabricated in a sandwich structure and characterized using Solar Simulator. The graphite exfoliation was conducted by sonication and microwave energy, as well as the electrochemical method. Cis-oleyl-imidazolinium iodide efficiency (0.53%) was highest than stearyl-imidazolinium iodide and palmityl-imidazolinium iodide because cis-oleyl-imidazolinium iodide has a double bond and the longest alkyl chain which triggered a self-assembly structure formation and increased the rate of I-/I3- transport in cells. Then, the efficiency of DSSCs-based composite electrolytes was in the range of 0.020– 0.203%. Dispersion of 0.05% of the graphite results in efficiency enhancement of about 100%, but the greater fraction (0.10%) of the graphite causes a poor performance (lower efficiency), possibly due to interference of the internal electron transportation routes in the DSSC by insoluble graphite. After exfoliation, the conductivity of synthetic graphite (11.58 x 10-1 S/cm), new battery graphite (9.32 x 10-1 S/cm), and battery waste graphite (7.96 x 10-1 S/cm) were increased respectively 10 times, 2 times, and 4 times from the graphite before exfoliation due to changes in crystallinity, the distance between layers, crystal size, formation of multilayer graphene, and the occurrence of π to π* transition. This enhancement of solar conversion efficiency can give a new contribution to the development of DSSC.

Investigation on the parameter dependency of the perforation process of graphite based lithium-ion battery electrodes using ultrashort laser pulses

Perforation of lithium-ion battery electrodes has recently become an increasing interest in science and industry. Perforated electrodes have shown improved electrochemical properties compared to conventional, nonperforated electrodes. It has been demonstrated that through perforation, the fast-charging capability and the lifetime of these batteries can be significantly improved. The electrodes for lithium-ion batteries consist of a copper foil onto which the electrode material is applied as a porous layer. This layer is mainly composed of active material particles, which are bound together by a binder phase. Here, synthetic graphite was used as an active material. Up to now, it has been shown that an advantageous and precise perforation geometry can be produced by ultrashort laser pulse ablation. Since the ablation volumes during perforation of the porous electrode material with ultrashort laser pulses are unusually high compared to solids, this work investigates the parameter dependency on the ablation mechanisms in detail. For this purpose, in particular, single-pulse ablation was investigated with respect to the ablation thresholds at different pulse durations. The pulse durations were varied over a large range from 400 fs to 20 ps. By varying the number of pulses per perforation up to 50 and the single-pulse energy up to 45 μJ, it could be shown that a homogeneous ablation down to the conductor foil through the 63 μm thick active material layer can be achieved.

Dependence of Precursor Graphite Flake Size on Nitrogen Doping in Graphene Oxide and Its Effect on OER Catalytic Activity.

We report the synthesis of nitrogen-doped graphene oxide, with 5.7–7.0 wt % nitrogen doping, from different sizes of precursor graphite and study its effect on the oxygen evolution reaction (OER) activity of IrO2 in an acidic medium. The nitrogen-doped supports are expected to have pyridinic, pyrrolic, and graphitic functionalities at different ratios responsible for their improved performance. The N-doped supports and catalysts are synthesized via pyrolysis and the hydrothermal method using natural and synthetic graphite of three different flake sizes and evaluated for their structural and electrochemical characteristics. The average size of IrO2 nanoparticles deposited on the N-doped supports is independent of the flake size and doping amount of nitrogen. The catalysts show optimum current densities but improved stability with increasing flake sizes of 7, 20, and 125 μm. Our results demonstrate that the selection of the flake size of the doped support is necessary to achieve durable catalysts for the OER in an acidic medium.

Preparation of Onion-like Synthetic Graphite with a Hierarchical Pore Structure from Anthracite and Its Electrochemical Properties as the Anode Material of Lithium-Ion Batteries

Graphite is commonly used as the anode material for lithium-ion batteries (LiBs). However, as natural graphite is unevenly distributed worldwide and its exploitation cost is continuously increasing, there are growing appeals for developing high-performance synthetic graphite as the anode material of LiBs. In this work, synthetic graphite with an onion-like porosity-rich structure was obtained from anthracite, and its electrochemical performance as the anode material of LiBs was investigated. The results reveal that the presence of Fe2O3 content in anthracite could regulate the carbon matrix to form an onion-like structure. The oxidation and heat treatment were helpful to expand the interlayer spacing of the graphite sheets, and the subsequent KOH activation could create a considerable amount of mesopores and micropores in the graphite, which could offer more chances for the intercalation–deintercalation of lithium ions and provide more sites and paths for the accommodation and transportation of lithium ions. As a result, the obtained graphite exhibited a favorable electrochemical performance regarding charging–discharging capability, cyclic voltammetry, rate performance, and cycling stability. The findings could provide an alternative method for the preparation of anode materials for LiBs and may have implications for taking advantage of anthracite resources.

(Digital Presentation) Fabrication of Conductive Carbon Composite Films for Freestanding Lib Anodes Using Cellulose Nanofiber Binder

Fig.1 Cycle performance and Coulomb efficiency of graphite/CNT/CNF composite electrodes Introduction Currently, lithium-ion batteries (LIBs) have been the primary power source for electric vehicles and portable devices. LIBs consist of anodes (e.g. graphite), cathodes (e.g. LiCoO2: LCO), and electrolytes,[1] and are dis-/ charged as Li+ de-/ intercalate between the electrodes. Since LIBs require expensive fluorinated polymer as binders (e.g. poly (vinylidene fluoride): PVDF) and a volatile and toxic organic solvent such as N-methyl pyrrolidone (NMP), cheaper and easier-to-handle materials are necessary. Furthermore, the metal substrates (Cu, Al foil, etc.) as the current collectors are heavy and reduce the weight energy density of electrodes. Therefore, providing alternatives to the conventional components of LIB electrodes is a key challenge. Developing functional nanocomposites using sustainable natural resources is one of the most importance strategies.[2] Conductive thin films of cellulose nanofibers (CNFs) combined with carbon nanotubes (CNTs) have been reported as novel carbon composites.[3] Environmentally friendly and only carbonaceous electrodes without PVDF and organic solvents, and graphite are normally used for anodes. As an allotrope of graphite, CNTs have been approved to be a suitable anode material due to their unique structure (one-dimensional cylindrical tubule of graphite sheet), high conductivity (106 Sm-1 at 300 K), low density, high rigidity (Young’s modulus 1 TPa), and high tensile strength (up to 60 GPa).[4] In this study, the free-standing carbon composite anodes were successfully fabricated by using ultrasonication of CNF/ CNT or graphite mixture and vacuum filtering. Graphite slurry as the active material layer was dispersed in DI-water as the solvent containing CNF binder. This composite film has a dual-layer structure consisting of graphite/CNF active materials layer and CNT/CNF layer; here, the CNT/CNF layer with a thickness of about 10 μm is utilized as a current collector replacing the conventional metal substrate. These fabricated electrodes were evaluated by structural evaluation and dis-/ charge measurements. Experimental method CNF gel (2 wt%, Rheocrysta, DKS Co. Ltd.) and functionalized (carboxylic acid) multi-walled CNT (f-MWCNT, Sigma-Aldrich) were suspended in DI-water and sonicated for 2 h. Synthetic graphite was dispersed in DI-water with 5 wt% CNF and 10 wt% Carbon Black (CB) as a conductive material and sonicated for 30 min. Nanocomposite dual-layer films were formed by vacuum-filtering the dispersion using PVDF (pore size: 0.1 μm) membrane filters. These films were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), and Raman spectroscopy. The conductivity was measured by four probe method. The electrochemical properties of the free-standing electrode were measured using coin cells at room temperature. The coin cells were assembled in an argon-filled glovebox using Li as a counter electrode, glass fiber filter as a separator, and 1 M LiPF6 in a 1:1 (volume) mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as the electrolyte. Charge-discharge characteristics were recorded from 0.01 to 3 V at charging speeds of 0.1 – 2 C. The electrochemical impedance spectra (EIS) were measured in the frequency range from 100 mHz to 100 kHz with a potential perturbation at 5 mV. Results CNF combined with CNT constructs a robust conductive fibrous network, and CNT linked with graphite builds electronic conductive paths to improve the electronic conductivity. Specific capacities of the electrode were 44 mAhg-1 at 2 C and 272 mAhg-1 at 0.5 C, respectively (Fig.1). The discharge capacity of the first cycle was 363 mAhg-1 at 0.1 C. After 125 cycles, the discharge capacity was 255 mAhg-1 at 0.5 C. The ratio of the charge and discharge capacities (Coulombic efficiency) suggests that the charge-discharge behavior is stable in the cycle measurement, indicating that the irreversible capacity was small. Other information obtained by cyclic voltammetry (CV), and EIS measurement and further results will be shown in the presentation. In summary, we successfully fabricated the graphite/CNT/CNF composite film as environmentally friendly and lightweight anodes for the first time. The present results indicate that graphite/CNT/CNF composite film is a good candidate of flexible free-standing anodes. This research focused on CNFs as a promising alternative to conventional battery materials, and CNFs were successfully used to fabricate electrodes without using expensive PVDF binders and toxic organic solvents. Moreover, the gravimetric energy density was improved by replacing the conventional heavy Cu foil with a lightweight and thin composite film of CNT/CNF.

Recycled Graphite for Sustainable Lithium-Ion Batteries

Graphite – natural or synthetic – is the most dominant active material used for LIB anodes[1]. Natural graphite, however, is considered a critical material within the EU[2], while synthetic graphite is obtained from coke[3] – a carbon precursor produced from coal or petroleum. Therefore, efficient recycling and reuse of graphite are essential towards sustainability and resource preservation[4].Herein, we report a novel and highly efficient process to recover high-quality graphite from spent LIBs. Following a comprehensive physicochemical characterization of the materials obtained, we conducted an extensive electrochemical characterization in half-cells and graphite‖NMC532 full-cells and compared the results with the data obtained for half-cells and full-cells using pristine commercial graphite. In half-cells, the recycled graphite shows remarkably high reversible specific capacities (e.g., 350 mAh g- 1 at C/20) and very stable cycling for several hundred cycles at 1C. The graphite‖NMC532 full-cells also show excellent cycling stability, with a capacity retention of 80% after about 1,000 cycles. Particularly, the comparison with the pristine graphite comprising full-cells reveals very comparable performance, highlighting the great promise of recycled and reused graphite as a pivotal step towards truly sustainable LIBs and the great goal of a circular economy.

Graphene Oxide Production Via Exfoliation Process of Low-Temperature Synthetic Graphite from Oil Palm Trunk Waste

Graphene Oxide Production Via Exfoliation Process of Low-Temperature Synthetic Graphite from Oil Palm Trunk Waste

Fabrication of Bipolar Plates from Thermoplastic Elastomer Composites for Vanadium Redox Flow Battery.

A vanadium redox flow battery (VRFB) is a promising large-scale energy storage device, due to its safety, durability, and scalability. The utilization of bipolar plates (BPs), made of thermoplastic vulcanizates (TPVs), synthetic graphite, woven-carbon-fiber fabric (WCFF), and a very thin pyrolytic graphite sheet (GS), is investigated in this study. To boost volumetric electrical conductivity, WCFF was introduced into the TPV composite, and the plate was covered with GS to increase surface electrical conductivity. Created composite BPs acquire the desired electrical conductivity, mechanical strength, and deformation characteristics. Those properties were assessed by a series of characterization experiments, and the morphology was examined using an optical microscope, a scanning electron microscope, and atomic force microscopy. Electrochemical testing was used to confirm the possibility of using the suggested BP in a working VRFB. The laminated BP was utilized in a flow cell to electrolytically convert V(IV) to V(V) and V(II), which achieved comparable results to a commercial graphite bipolar plate. Following these experiments, the laminated bipolar plates’ surfaces were examined using X-ray photoelectron spectroscopy, and no evidence of corrosion was found, indicating good durability in the hostile acidic environment.

Friction and Wear Behavior of Graphene and Graphite Oxide–Reinforced Epoxy Composites

Graphene has gained prominence owing to its excellent mechanical, thermal, and electrical properties. Indeed, polymer–graphene composites have demonstrated superior mechanical properties over monoliths and are well suited for seals and bearings. The objective of this work was to gain a fundamental understanding of the friction and wear mechanics of epoxy reinforced by graphene-based fillers. Epoxy composites were prepared with three commercially available graphene/graphite fillers identified as KS6, synthetic graphite powder; xGNP, graphene platelets; and iGO, industrial graphite oxide and tribologically evaluated in a ball-on-disc configuration at sliding velocities from 0.047 to 1.61 m/s. It was found that only the epoxy +5 wt% iGO demonstrated a lower wear rate among other fillers, with 1 wt% being the best for a range of iGO content. The addition of iGO improved the friction and wear resistance due to functional groups on the surface and the resulting enhanced adhesion; it was the nature of the surface film rather than the bulk polymer that dictated the tribological response. Although further studies are warranted, there are indications that harder particles such as iGO may have limited the rate of detachment and wear by arresting crack propagation in the matrix and filler dispersion. The wrinkled morphology of iGO led to better interlocking with the matrix, thereby limiting the detachment of particles; the filler–matrix interaction between functional groups on the graphene oxide surface may also play an important role. These results have important implications for improving the manufacture of composites with superior tribological and mechanical properties.

The Effect of the Heating Rate during Carbonization on the Porosity, Strength, and Electrical Resistivity of Graphite Blocks Using Phenolic Resin as a Binder.

In the present study, graphite blocks were fabricated using synthetic graphite scrap and phenolic resin, and the effect of the heating rate during carbonization on their mechanical and electrical characteristics was examined. While varying the heating rate from 1, 3, 5, and 7 to 9 °C/min, the microstructure, density, porosity, flexural strength, compressive strength, and electrical resistivity of the fabricated graphite blocks were measured. As the heating rate increased, the pores in the graphite blocks increased in size, and the shape of the gas release paths became more irregular. Overall, it was found that increases in the heating rate led to the degradation of the graphite blocks’ mechanical and electrical properties.

Few-layer graphene as an additive in negative electrodes for lead-acid batteries

To overcome the problem of sulfation in lead-acid batteries, we prepared few-layer graphene (FLG) as a conductive additive in negative electrodes for lead-acid batteries. The FLG was derived from synthetic graphite through liquid-phase delamination. The as-synthesized FLG exhibited a layered structure with a specific surface area more than three times that of pristine synthetic graphite. The thickness of the as-synthesized FLG was determined through atomic force microscopy to be approximately 4 nm (<10 layers). To enhance the electrochemical performance of lead-acid batteries, we introduced pristine synthetic graphite and FLG into negative electrodes, denoted NAM(G) and NAM(FLG), respectively. Charge/discharge tests revealed that the initial discharge capacity of the FLG-based electrode was 4173 mAh, which was 110% higher than that of the graphite-based electrode. The cycle life of NAM(FLG) was 120 cycles, which was approximately two times higher than that of NAM(G). The impedance of NAM(FLG) was 0.226 Ω, which was significantly lower than that of NAM (16.1 Ω). Our findings indicate that incorporating FLG into the negative electrodes of batteries can result in significant performance enhancements and prolonged cycle life through the inhibition of sulfation.

Highly Conductive Polymer Composite Based on Graphite-Filled Immiscible Polyolefin/Epoxy Blends

Conductive polymer composites (CPCs) based on polypropylene (PP)/epoxy (EP) and high-density polyethylene (HDPE)/EP blends filled with synthetic graphite (SG) were produced and characterized to explore their potential for high electrical conductivity applications. The polymer blends were chosen as matrices due to their immiscibility and potential to enable co-continuous morphology formation and preferential distribution of filler, which allows formation of maximized conducting networks. In-plane and through-plane resistivities of PP/EP/SG composites decreased from 0.083 Ω.cm to 0.015 Ω.cm and 10.16 Ω.cm to 0.31 Ω.cm, respectively, while for HDPE/EP/SG composites, in-plane and through-plane resistivities decreased from 0.086 Ω.cm to 0.014 Ω.cm and 5.02 Ω.cm to 0.24 Ω.cm, respectively, when SG content was increased from 30 to 80 wt%. The immiscible blend-based composites produced in this study have the potential to achieve significantly higher conductivity than filled single polymers due to concentration of filler in one of the polymer phases and the co-continuous structure of the blends. Also, resistivity anisotropy of the PP/EP/SG and HDPE/EP/SG composites generally decreased with increase in SG content, with HDPE/EP/SG composites showing lower resistivity anisotropy than PP/EP/SG composites at the same SG content.

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.

Effective adsorptive removal of dyes and heavy metal using graphene oxide based Pre-treated with NaOH / H2SO4 rubber seed shells synthetic graphite Precursor: Equilibrium Isotherm, kinetics and thermodynamic studies

Graphene oxide (GO) has excellent adsorption capacity as a promising adsorbent due to its large surface area consisting of large number of oxygen-functional groups. Nonetheless, the properties of GO are heavily influenced by the graphite sources and the type of pretreatment. This study aims to investigate the effect of pre-treatment of graphite sourced from agricultural wastes on the properties of the GO for the adsorption of dyes and heavy metal ion. Two sources of graphite (pre-treated with NaOH and H2SO4) were synthesised using biomass wastes (rubber seed shells) and were utlilized to produce high-efficiency GO for the adsorption of Methylene blue (MB), Congo red (CR) and Cadmium (II) from aqueous solutions. The effect of pre-treatment on the GO properties, behavior and performance was evaluated through batch adsorption studies which were conducted under operational condition of activation temperature (25–55 ○C), contact time (2–20 min), dosage (0.02–0.1 g), pH (2–12) using impregnation ratio of 1:4. The morphological analysis revealed that GO pretreated with NaOH (GO-N) graphite source exhibited more porous surface area compared to GO pretreated with H2SO4 (GO-H) graphite source, the surface properties was attributed to higher oxygen ratio as indicated in the EDX mapping and as demonstrated in the BET analysis. In general, both GO demonstrated excellent adsorption capacity due to their single-layered planes with noticeable functional groups which included hydroxyl, alkoxy, and carboxyl groups along with the π − π interactions and hydrogen bonds. Maximum monolayer adsorption capacities for the effective removal of CR, MB and Cd (II) was achieved as 299.38, 311.54, and 107.65 mg g−1 respectively onto GO-N compared to GO-H as illustrated by the Langmuir isotherms. Furthermore, the results showed that the experimental data were well-fitted to the pseudo-second-order model for both CR and MB including Cd (II) with GO-N with higher correlation coeficient R2 (R2 > 0.9) recorded. Thermodynamic study signified that the enthalpy (ΔH) and Gibbs free energy (ΔG) values of the adsorption process for both pollutants were negative indicating that adsorption of CR, MB and Cd were spontaneous and exothermic in nature which suggests that the adsorption of dyes and heavy metal from an aqueous solution was attributed to the presence of active sites and functional groups on the GO surface. However, the study revealed that GO–N proved to be a better adsorbent compared to GO-H under same operational condition and can be considered as a promising and cost-effective adsorbent for the removal of dyes and metal ions from industrial wastewater.

Emergy-based environmental accounting of graphite anode material production

Natural graphite is often regarded as a critical mineral because it is currently the most widely used battery anode material (BAM) for commercial lithium-ion batteries. However, studies on evaluating the criticality of natural graphite are still lacking, especially how to evaluate its substitutability from an environmental perspective. Emergy is defined as the sum of all the solar energy required to generate a product or service and emergy synthesis is one effective method for environmental accounting. This study employs an emergy synthesis method to compare the efficiency and sustainability of BAM production processes with different raw material inputs - natural graphite and its major substitute synthetic graphite. The overall environmental performance of graphite BAM production is also examined by evaluating the contribution of natural capital and ecosystem services. Results show that the total emergy input for natural graphite BAM production was 4.72E+10 sej/g, dominated by natural graphite deposit, while the total emergy input for synthetic graphite BAM production was 2.34E+10 sej/g, dominated by petroleum coke and electricity. Based on the emergy indicators, the BAM production from synthetic graphite is considered as a preferable option because such production process will lead to better economic and environmental performances and improve the overall resource efficiency. These results also imply that the criticality of natural graphite might be overestimated since the substitution of synthetic graphite in BAM manufacturing is economically and environmentally feasible.

Shear enhancement of mechanical and microstructural properties of synthetic graphite and ultra‐high molecular weight polyethylene carbon composites

AbstractUltra‐high molecular weight polyethylene (UHMWPE) has a variety of industrial and clinical applications due to its superb mechanical properties including ductility, tensile strength, and work‐to‐failure. The versatility of UHMWPE is hindered by the difficulty in processing the polymer into a well consolidated material. This study presents on the effects of shear imparted by equal channel angular pressing (ECAP) on UHMWPE composites containing Nano27 Synthetic Graphite (N27SG). Ductility and work‐to‐failure improvements up to ~60–80% are obtained in sheared N27SG‐UHMWPE composites as compared to non‐sheared N27SG‐UHMWPE controls of the same composition. Microscopy reveals increased fusion at particle boundaries and smaller voids in the sheared materials. Micro‐computed tomography results indicate different distribution of N27SG particulates in ECAP samples as compared to CM indicating enhanced grain boundary interactions. Tradeoffs are not avoided as ECAP samples were lower in conductivity as compared to compression molded (CM) billets of the same weight percent. However, ECAP samples were able to be doped with more N27SG allowing for an ~170% increase in conductivity over CM samples of the same work‐to‐failure. This work shows that ECAP is a viable processing method for obtaining stronger, more ductile conductive composite materials.

Toward a life cycle inventory for graphite production

AbstractGlobal electrification of mobility and energy storage is driving an unprecedented demand for lithium‐ion batteries (LIBs) for which graphite is one of the major components. Multiple prior studies have attempted to assess the environmental footprint of LIBs by way of life cycle analysis (LCA), and the poor quality of inventory data on the production of graphite (at various purities) has been highlighted consistently. This work reviews the available inventories used in the assessment of natural and synthetic battery‐grade graphite production, and demonstrates that some upstream, downstream, and peripheral processes—including important processes associated with mining, calcination, and other steps—are often omitted, leading to greatly underestimated impacts. It proposes a new rigid framework for comparing different graphite production routes and a corresponding indicative inventory for synthetic graphite production. This inventory is used to estimate the global warming potential and energy demand of synthetic graphite, yielding results of 13.8 kgCO2‐eq/kg and 45.9 MJ/kg, respectively, suggesting that prior literature may have underestimated these results by a factor of two or more. The work concludes by highlighting the need to evaluate a broader suite of applicable impact categories and to fully account for the full suite of by‐and co‐products in future LCAs.

Catalytic graphitization in anthracite by reduced iron particles and investigating the mechanism of catalytic transformation via molecular dynamics

Anthracite graphitization was catalyzed by reduced iron particles, where iron was introduced in the form of Fe2O3, reduced during the carbothermal reaction. This graphite as an alternative solution for the lithium-ion battery anode material, and the precursor of the anode material was obtained. The degree of graphitization of synthetic graphite regulated via changing the amount of Fe2O3 and catalytic temperature. Graphite with the graphitization degree of 96.51% was obtained under the conditions of the catalytic temperature of 2400 °C, Fe2O3 content of 20%. HRTEM of graphite after Fe-catalyzed graphitization revealed that the graphite layer spacing gradually approached the ideal graphite. Molecular dynamics (MD) provides significant insight into the mechanism of Fe-catalyzed graphitization at the molecular level. The mechanism of Fe-catalyzed graphitization was inevitably related to the formation and breakage of Fe–C bonds. With the formation and breakage of Fe–C and C–C bonds, a regular aromatic 6-membered ring was finally formed due to the strong bonding between Fe and C. Fe promoted the integration of irregular 5- and 7-membered rings into two regular aromatic 6-membered rings. These two processes were continued in the process of catalytic graphitization. This result provided MD support to explore the mechanism of Fe-catalyzed graphitization.

Silicate conductive composites with graphite-based fillers

Electroconductive composites are modern materials that are commonly used in many industries such as construction industry and machine-building industry. For example, these materials can be useful as sensors for monitoring changes in constructions, shielding stray currents from electrification networks, shielding electromagnetic radiation in operating rooms, cathodic protection against moisture or overvoltage protection of buildings. The topic of this post is the research of electrically conductive silicate composites with graphite-based fillers. In this research will be tested composites with different ratio and types of graphite and monitor their electroconductive properties like impedance, and physical-mechanical properties like compressive and tensile strength. The post describes basic properties and interactions of silicate electrically conductive composites with graphite fillers. It was found that by adding 10 % wt. graphite into silicate composites, impedance is reduced by 50% and compressive strength by 40%. The flexural tensile strength depends mainly on the roughness of the particles, where the coarser flaky particles transfer the load better and increase the strength while very fine graphites reduce the flexural tensile strength. Furthermore, it has been found that very finely ground synthetic graphites are most suitable for achieving low impedance of composites.

(Physical and Analytical Electrochemistry Division Max Bredig Award Address In Molten Salt and Ionic Liquid Chemistry) Electrochemical Graphitization via Molten Salts

Graphite is considered by the US Department of Energy to be a critical element. Due to its widespread use as anodes in batteries, the demand for high purity graphite for battery applications is expected to increase for the foreseeable future. Synthetic graphite, due to its high purity, is generally the preferred choice for battery applications. The current process for the synthesis of graphite is very energy intensive and requires heat treatment of carbon precursors to temperature up to 3300 K for successful graphitization. Herein, an electrochemical method for graphitization is reported, which requires significantly lower temperatures. The cathodic electrochemical polarization of amorphous carbons in molten salts at around 1100 K can transform amorphous carbons to highly graphitic carbon structures. This process is facilitated by molten salts and has the great potential to save significant energy compared to the current existing process.