Nongraphitic carbons

Other Cell Designs. Although not used in the United States, another important cell is based on designs developed by ICl (90). Cells of this type are used by British Nuclear Fuels pic and differ from the cells shown in Figures 2 and 3 in two ways (/) the anodes used are made of the same hard, nongraphitized carbon, but are more porous and 2) the cathodes are formed from coiled tubes and provide additional cooling (91). 

Synthetic Resins. Various polymers and resins are utilized to produce some specialty carbon products such as glassy carbon or carbon foam and as treatments for carbon products. Typical resins include phenoHcs, furan-based polymers, and polyurethanes. These materials give good yields of carbon on pyrolysis and generally carbonize directly from the thermoset polymer state. Because they form Httle or no mesophase, the ultimate carbon end product is nongraphitizing. 

The stmcture of activated carbon is best described as a twisted network of defective carbon layer planes, cross-linked by aHphatic bridging groups (6). X-ray diffraction patterns of activated carbon reveal that it is nongraphitic, remaining amorphous because the randomly cross-linked network inhibits reordering of the stmcture even when heated to 3000°C (7). This property of activated carbon contributes to its most unique feature, namely, the highly developed and accessible internal pore stmcture. The surface area, dimensions, and distribution of the pores depend on the precursor and on the conditions of carbonization and activation. Pore sizes are classified (8) by the International Union of Pure and AppHed Chemistry (lUPAC) as micropores (pore width <2 nm), mesopores (pore width 2—50 nm), and macropores (pore width >50 nm) (see Adsorption). 

The surface structure has a strong influence on the corrosion rate of carbon in both acid and alkaline electrolytes. Studies by Kinoshita [33] clearly showed that the specific corrosion rate mAcm"2 of carbon black in 96 wt% H3P04 at 160 °C was affected by heat treatment. A similar trend in the corrosion rate in alkaline electrolyte was observed by Ross [30c], as shown in Fig. 4. It is evident that the corrosion rates of the nongraphitized carbons are higher than those of the corresponding graphitized carbons. Their study further indicated that some types of carbon blacks (e.g., semi... 

In a study of the carbonization (- 525°C) and graphitization (- 2500°C) of thianthrene in comparison with anthracene, it was shown that the carbons of the heterocycle are nongraphitable between 1200°C and 2500°C, sulfur was evolved continuously (85MI3). Aluminum chloride catalytic carbonization of thianthrene has also been studied. At lower temperatures than without a catalyst, thianthrene produced an isotropic coke catalytic co-carbonization with anthracene and 9,10-dihydroanth-racene gave mosaic and needle cokes, respectively (80MI6, 80MI7). Po-ly(arylene sulfides) were shown to be produced by aluminum chloride treatment of thianthrene at 180-350°C (79URP659582). 

Do DD and Do HD. Modeling of adsorption on nongraphitized carbon surface GCMC simulation studies and comparison with experimental data. J. Phys. Chem. B, 2006 110(35) 17531-17538. 

Furthermore, the preparation of graphitic carbon materials requires high-temperature treatment, which is disadvantageous in production cost. The nongraphitic carbon obtained at around... 

FIG U RE 12.2 Typical voltage profiles from carbon materials with different heat-treatment temperatures and different structural variations. The profiles were obtained at the second cycle, and (a) and (b) show discharge and charge cycles by using graphitizable carbon heat-treated at 3000°C, graphitizable carbon heat-treated at 2000°C, and nongraphitic carbon obtained at 700°C. (Reprinted from Endo, M., et al., Carbon, 38, 183, 2000. With permission.)... 

Figure 32. Schematic representation of the modes of fixation of metal particles on graphitic surfaces. A stack of graphene layers with a step edge is shown with a metal particle (granite pattern) and surface anchoring groups (black). Nongraphitic carbon deposits are shown in dark grey with fading contrast (bottom sketch).

Figure 10.20 Structure model of different carbon materials, (a) nongraphitic carbon exhibiting inherent slit-shaped micropores, (b) multiwall carbon nanotube (MW-CNT),...

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