Figure 1.30 Production capacities for redox flow batteries.
Figure 1.31 Mechanical strength from carbon fibers to nanotubes.
1.5 Conclusion
The demand for traditional carbon and graphite products will be further growing and stay the basic business for the carbon and graphite industry. Despite the age of these products, there is still room for scientific research and innovation. The economic growth drives the resources of raw material to the edge. This is also the case for the production of carbon and graphite. Natural graphite is on the European list of short raw materials. Good quality anode coke went short with the strong growth in the production of aluminum. Crude oil refinery exits in a market with regional overcapacities might shorten the availability of petroleum needle coke in the future. Legislative actions in Europe (REACH) will limit the use of coal‐tar pitch and petroleum pitch. The industry would appreciate if academia would turn parts of their recourses back to this field and would work jointly with industry on these issues.
The debate about energy production, efficient use, and last but not least about CO2 release is impacting the human society globally. Lightweight construction with carbon fibers is a market with a huge potential to grow. Also in this field the close interaction between science and industry is necessary to solve open questions in materials science, production, and the development of alternative precursor and matrix systems.
Energy storage for e‐mobility and stationary systems needs further research and innovation. The area of nanoforms of the element carbon remains at the very beginning of commercialization.
2 The Element Carbon*
Wilhelm Frohs1 and Hubert Jäger2
1 SGL Carbon GmbH, Werner‐von‐Siemens‐Street 18, Meitingen 86405, Germany
2 Technische Universität Dresden, Institute of Lightweigth Engineering and Polymer Technology (ILK), Hohlbein Street 3, Dresden, 01307, Germany
2.1 Introduction
The element carbon is the 6th element with the symbol C in the periodic table with the atomic mass of 12.0. Its neighbors are boron with the atomic number 5, a semimetal. On the left side follows nitrogen with the atomic number 7, a nonmetal like the elements carbon, oxygen, phosphorus, and sulfur.
Boron can exist in several allotropic forms. The most stable crystalline form is ß‐rhombohedral boron, a very hard substance with a melting point of 2349 K. Like carbon, boron forms covalent bonded molecular networks, an amorphous form of boron. Together with the incorporation of other elements, this creates the basis for the organoboron chemistry. The simplest representative is diborane (B2H6). The capability to form covalent bonds between each other and to other elements culminates with the element carbon in an unlimited diversity.
The properties of these elements are compared in Table 2.1.
Nitrogen is a diatomic gas with three bonds between each other. The extreme bonding strength (945 m kJ/mol) dominates the chemistry of nitrogen. It took until 1910 to produce ammonia from nitrogen in an industrial scale (Haber–Bosch synthesis), which was honored with Nobel Prizes in 1918 and 1932.
The mass share of carbon on Earth is about 0.03% [1]. Its abundance relative to other elements is shown in Figure 2.1 [2]. Carbon has two stable isotopes: 12C and 13C. The isotope 14C is unstable and radioactive. This isotope is used for age determination in archeology. Its radioactive half‐life is rather short with about 5715 years [3]. The 14C radiocarbon dating was developed by Willard Frank Libby in 1946 and honored 1960 with the Nobel Prize [4].
The most important allotropes of carbon are diamond, graphite, and amorphous carbon (Figure 2.2). These three allotropes are of industrial relevance. The most important by volume is amorphous carbon. Fullerenes represent a new allotropic form whose industrial breakthrough is still pending despite their extraordinary physical properties. The structural forms of the different allotropes are shown in Figure 2.3 [5, 6] and Figure 2.4 [6].
Table 2.1 Physical properties of carbon and its neighbor elements. G=Graphite, D=Diamond.
| Property | Boron | Carbon | Nitrogen |
|---|---|---|---|
| Atomic number | 5 | 6 | 7 |
| Classification | Semimetal | Nonmetal | Nonmetal |
| State | Solid | Solid | Gas |
| Density, g/cm3 | 2.46 | G = 2.26, D = 3.53 | 0.00125 |
| Mohs hardness | 9.3 | G = 0.5, D = 10 | — |
| Melting point, K | 2349 | 3773 (sublimation) | 63.05 |
| Boiling point, K | 4203 | 5115 | 77.15 |
| Heat of evaporation, kJ/mol | 508 | 715 (sublimation) | 5.58 |
| Specific heat, J/kg K | 1260 | G = 709, D = 427 | 1040 |
| Electrical conductivity, S/m | 10−6 | G = 2–3·105, ∥ 3.3 102, ⊥ D = ∼ 10−13 | 0 |
| Thermal conductivity, W/mK |
|
