Graphitized mesophase carbon

Synthetic carbonaceous materials are widely used in these applications. Several types of synthetic materials (e.g. graphitized mesophase carbon microbeads (MCMB), graphitized milled carbon fiber, and even, initially, hard carbons) became the materials of choice at the time of commercialization of first successful lithium-ion batteries in late 1980s. New trends, mainly driven by cost reduction and need for improved performance, currently shift focus towards application of natural graphite. 

A typical resnlt is shown in Fig. 19.10. It shows the effectiveness of propane sulton (PS) as an anode additive to improve the high-temperature stability of the anode graphite. When MCMB (graphitized mesophase carbon) 6-28 is used as the... 

Graphitized mesophase carbon Japan 2,943,287 (Sept. 1990) Kawagoe, Ogino Bridgistone... 

The future remains bright for the use of carbon materials in batteries. In the past several years, several new carbon materials have appeared mesophase pitch fibers, expanded graphite and carbon nanotubes. New electrolyte additives for Li-Ion permit the use of low cost PC based electrolytes with natural graphite anodes. Carbon nanotubes are attractive new materials and it appears that they will be available in quantity in the near future. They have a high ratio of the base plane to edge plain found in HOPG. The ultracapacitor application to deposit an electronically conductive polymer on the surface of a carbon nanotube may be the wave of the future. 

Given the complex process to produce mesophase carbon (graphitized microbeads and fibers), natural graphite can be very competitive in terms of its manufacturing costs [18]. The physical characteristics of certain SLC type materials are extremely close to the characteristics of state-of-the-art MCMB grades. 

At the electrochemical performance level, these novel natural graphite-based materials surpass mesophase carbon s characteristics as related to cell/battery safety performance, low irreversible capacity loss, and good rate capability even at high current densities. 

Takami N, Satoh A, Hara M, Ohsaki T. Rechargeable Lithium-ion cells using graphitized mesophase -pitch-based carbon fiber anodes. J Electrochem Soc 1995 142 2564-2571. 

Microstructure Formation in Mesophase Carbon Fibers and Other Graphitic Materials... 

In the previous symposium, we reviewed mesophase mechanisms involved in the formation of petroleum coke ( 2 ). Since 1975, two significant developments have been the use of hot-stage microscopy to observe the dynamic behavior of the carbonaceous mesophase in its fluid state (3-6), and the emergence of carbon fibers spun from mesophase pitch (7-9) as effective competitors in applications in which high elastic modulus or good graphiticity is important. This paper focuses on mesophase carbon fibers as an example of how the plastic mesophase can be manipulated to produce fibers with intense preferred orientations and elastic moduli that approach the theoretical limit for the graphite crystal in the a-direction. 

This paper commences with evidence for lamelliform morphologies in mesophase carbon fiber, summarizes relevant information on disclination structures in the carbonaceous mesophase, and then reviews what we learn of disclination behavior from hot-stage observations and from deformation and carbonization experiments. The results indicate that disclination interactions that occur before the mesophase is fully hardened play an important role in determining the microstructures of mesophase carbon fibers, as well as those of cokes and graphites that form through the carbonaceous mesophase. 

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