Metal Chloride-graphite Intercalation Compounds Research Articles

Thermal decomposition and gas release properties of metal chloride-graphite intercalation compounds prepared utilizing polyimide film-derived graphite sheets

Abstract We have reported that metal chloride-graphite intercalation compounds (GICs) prepared from flexible polyimide film-derived graphite sheets, such as CuCl2-, MoCl5-, and AlCl3-CuCl2-GICs, demonstrate excellent air stability. In this work, the high-temperature thermal stability and gas release properties of those GICs were investigated. MoCl5- and AlCl3-CuCl2-GICs were unstable at high temperatures, exhibiting weight losses at 150 °C and 100 °C, respectively, which accompanied the release of HCl and Cl2 gases. In contrast, the CuCl2-GIC demonstrated relatively high thermal stability in inert atmospheres at temperatures below 400 °C, showing neither weight loss nor gas release. After heat treatment at 600 °C at a heating rate of 5 °C/min, only a slight decrease in the electrical conductivity was observed.

Layer Controllable Graphene Using Graphite Intercalation Compounds with Different Stage Numbers through Li Conversion Reaction

Graphene with controlled stacking numbers and fewer defects is synthesized through an electrochemical approach using metal chloride graphite intercalation compounds (GICs) via a lithium conversion reaction. Using GICs with different stage numbers as precursors, graphene with different layers is successfully obtained. The mobility estimated from the transport measurement is around 4000 cm2 V−1 s−1, which is comparable to the micromechanically cleaved bilayer graphene. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Novel approaches for controlling stage structure of metal chloride–graphite intercalation compounds

Intercalation of EuCl3 TbCl3, and AlCl3 into graphite was carried out in the presence of chlorine. The observation of products by x-ray diffraction showed that the extent of chloride intercalation could be controlled through adjustment of the pressure of chlorine; increasing pressure tended to increase the extent of intercalation. In the case of EuCl3, the extent of intercalation varied to show a stage transition. In contrast, TbCl3 intercalation gave a mixture of stage 2 or stage 4 graphite intercalation compound (GIC) and remaining graphite, where the extent of intercalation is revealed by the ratio of GIC to graphite. With respect to AlCl3 intercalation, although the preparation of stage 1, 2, and 4 GICs was successful, stage 3 and 5 GICs could not be obtained.

Ternary Metal Chloride Graphite Intercalation Compounds Synthesized from Chlorometallate Salts

The action of MCl2-AlCl3 molten salt systems (M˭Cu, Cd, Pd, Co) does not permit the intercalation into graphite the heteromolecules MAl2Cl8 which exist in the liquid. All these molten chloroaluminate reagents give intercalated species which correspond to an AlCl3 layer with low divalent ionic content the basal plane structure of which appears to be dependent on the divalent metal. In the case of copper, palladium and cobalt, this 2D order corresponds to a hexagonal cell (a=600pm) whose study based on the experimental and calculated (hko) intensities suggests a substitutional process between the Al3+ and M2+ ions in the intercalated layers.

Reaction of Metal Chloride Graphite Intercalation Compounds with Ammonia

Abstract The uptake of ammonia by copper chloride graphite intercalation compounds was studied. The products obtained can be represented by the formula {xC}CuCl2·nNH3. They are regarded to be occlusion complexes. The thermal decomposition of these complexes has been studied and compared with those of ammine complexes of CuCl2. The techniques used were thermogravimetric analysis supported by chemical analysis and X-ray diffraction. When heated in a slow stream of ammonia or nitrogen, ammonia is lost in steps, which are better defined when the decomposition takes place in ammonia. The decomposition finally leads to the formation of CuCl mixed with graphite.

Reaction of Metal Chloride Graphite Intercalation Compounds with Ammonia

Abstract The reaction of metal chloride-GIC with ammonia has been examined from the kinetic, thermodynamic and structural points of view. This reaction, which is widely reversible between two values of the ammonia/metal chloride ratio, can be used for the chemical storage of thermal energy or cold generation. The reaction rates have been found to be larger than those of non graphitic metal chlorides. The diffraction studies show that the final compounds are inclusion compounds rather than GIC. This structure allows an easy transfer of the ammonia molecules between inside/outside graphite crystallites.

Chloride-fluoride-graphite ternary compounds: Preparation and characterization

Stage 1 ternary MCl n-M′F n′-graphite bi-intercalation compounds ( M = Fe, Co, or Cu and M′ = B or Nb) have been prepared by the reaction of a fluoride vapor (BF 3 or NbF 5), under fluorine gas, with stage 2 metal chloride-graphite intercalation compounds (FeCl 3, CoCl 2, or CuCl 2-GIC). The reaction products were characterized by X-ray diffraction, FT-IR spectroscopy, and 19F NMR measurements. The measured repeat distances, I c , fit well with the sums of the respective repeat distances d 1 ( MX n - G), which would be exhibited by the stage 1 metal halogenide-GIC ( I c = d 1 (MC1 n-G) + d 1(M′F n′-G)). Unusual NMR line-shifts have been observed with compounds containing magnetic species such as Fe and Co. On the basis of these results, a three-step mechanism for the intercalation of a second reagent, M′ X′ n′ , into stage 2 MX n - GIC binary compounds is proposed. At first, a ternary bi-intercalation phase is formed, then a cointercalation phase can be obtained to finally give binary M′ X′ n′ -GIC in the third step. This would permit the obtention of original binary compounds which do not form by the more conventional procedures.

Synthesis of Graphite Intercalation Compounds in Molten Salts of Metal Chlorides

The intercalation process of metal chlorides into graphite and the formation of stage structures of intercalation compounds in the molten salts of various metal chlorides, and also the state of intercalated metal chlorides in the compounds were summarized on the basis of experimental results. Advantages and disadvantages of the synthesis of metal chloride-graphite intercalation compounds in their molten salt systems were discussed.1. Introduction2. Synthesis procedure and controlling factors3. Formation process of graphite intercalation compounds4. Control of stage structure in moten salts5. State analysis of intercalates6. Exfoliation of graphite films and electrical conductivity7. Advantages and disadvantages of molten salt method

Study of the structures of intercalate layer in metal chloridegraphite intercalation compounds by using EXAFS and XANES

The structures of intercalate layer in several metal chloride-graphite intercalation compounds (GICs) were studied by the analysis of extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES). The intercalated CuCl2 in CuCl2-GIC maintains a similar layer structure with long-range-order to that in anhydrous CuCl2 crystal. The structure of intercalated iron chloride in its GIC obtained in FeCl3-KCl molten salt is similar to that in the ternary GICs with iron chloride and nickel chloride, which are synthesized by using either a mixture of FeCl3 and NiCl2 or a FeCl3-NiCl2-KCl molten salt. In these ternary compounds, iron and nickel chlorides intercalated have a long-range-order in their layers and seem to exist in separated domains.

Bi-intercalation process of high stage metal chloride-graphite intercalation compounds

Stage-4 AlCl3-GIC prepared by the standard two-zone method were oxidized galvanostatically in H2SO4. The X-ray diffraction data indicate the stepwise intercalation of H2SO4 into host graphite and no formation of the GBC is observed, whereas AlCl3 is deintercalated in an early step of the reaction. In the case of the stage-4 MoCl5-GIC, the galvanostatic oxidation caused the stepwise bi-intercalation of H2SO4 into the host GIC as well as the displacement of MoCl5 by H2SO4.Alternatively, AlCl3 vapour was allowed to react with stage-3 FeCl3-GIC. The competition between the displacement reaction of FeCl3 by AlCl3 and the stepwise bi-intercalation of AlCl3 into the stage-3 FeCl3-GIC was observed.The bi-intercalation process of such a high stage GIC is explained with a schematic chemical potential diagram, comparing the bi-intercalation into stage-2 GIC.

Investigations of the nucleation process of metal chloride-graphite intercalation compounds

The nucleation of the intercalating substance is an equilibrium reaction, for which the law of mass action is valid. Therefore threshold activities of the reacting molecules must be surpassed in order to obtain an intercalation compound. A standard X-ray procedure was developed, by which the beginning of the reaction can be recognized. For some metal chloride GICs the composition of the nuclei and the equilibrium constants of the nucleation reaction are reported. Complications in the evaluation procedure owing to the association of metal chloride molecules and surface effects are discussed.

Formation of metal chloride-graphite intercalation compounds in molten salts

Three molten salt systems, FeCl 3KCl, CuCl 2KCl and CuCl 2NaCl, were used to synthesize metal chloride-graphite intercalation compounds. Binary compounds, FeCl 3GICs and CuCl 2CICs, were obtained in the corresponding molten salts. The stage structure of GICs obtained was found to be governed by the composition of the molten salt and the reaction temperature. The behaviour of the formation of GICs in a molten salt has a close relation to its phase diagram: the formation of a complex chloride, e.g., KFeCl 4, reduces the amount of reagent chloride and its reactivity, and consequently has a strong influence on the final stage of the compound and the intercalating rate.

Battery electrodes based on metal chloride-graphite intercalation compounds

The potentialities of graphite intercalation compounds as electrode materials in batteries are investigated. Emphasis is given to intercalated metal chlorides and their use in aqueous batteries. We show how classical systems can be improved and give examples of possible new electrode materials.

New theory for magnetic graphite intercalation compounds: Superferromagnetism in two dimensions

We calculate the high-field and low-field in-plane magnetic susceptibilities of the transition metal chloride graphite intercalation compounds (GIC) whose spins are confined to the plane. We show that the two observed low temperature susceptibility peaks can be due to a single phase transition which occurs near the higher temperature peak. The model assumes superferromagnetism, intra-plane and inter-plane super-moment interactions, and plane to plane variations of the intercalant concentration. The parameters which we introduce are estimated for several compounds. The resultant susceptibility curves have the observed temperature and field dependences and many other formerly peculiar aspects of the magnetism are explained. Notibly, the exceptionally large magnitude of the measured susceptibility, the non-zero sample magnitization between the two susceptibility peaks, and the stage dependence of the susceptibility curves.

559. Rectification at the metal-selenium interface: H P D Lanyon and R E Richardson, Phys Stat Sol (a), 7 (2), Oct 1971, 411–419

We calculate the high-field and low-field in-plane magnetic susceptibilities of the transition metal chloride graphite intercalation compounds (GIC) whose spins are confined to the plane. We show that the two observed low temperature susceptibility peaks can be due to a single phase transition which occurs near the higher temperature peak. The model assumes superferromagnetism, intra-plane and inter-plane super-moment interactions, and plane to plane variations of the intercalant concentration. The parameters which we introduce are estimated for several compounds. The resultant susceptibility curves have the observed temperature and field dependences and many other formerly peculiar aspects of the magnetism are explained. Notibly, the exceptionally large magnitude of the measured susceptibility, the non-zero sample magnitization between the two susceptibility peaks, and the stage dependence of the susceptibility curves.