Thermal expanded graphite

The mechanisms and reasons of catalytic activity of polyaniline (PANI)-type conducting polymers toward oxygen reduction in acidic and saline solutions are investigated by electrochemical and quantum-chemical methods. The PANI/thermally expanded graphite compositions were developed for realization of fully functional air gas-diffusion electrodes. Principally new concept for creation of rechargeable metal-air batteries with such type of catalysts is proposed. The mockups of primary and rechargeable metal-air batteries with new type of polymer composite catalysts were developed and tested. 

The samples of expanded (thermally expanded) graphite (TEG) were provided by the Central Research Institute of Materials (Russian Federation). TEG is a powder of light grey color with low bulk density and extremely developed true surface it can be easily pressed in a flexible plate ( cardboard ). The anodes made of TEG, had the capacity about 200 mA-h/g (Figure 5). However, in spite of the fact that the anodes were made of pressed powder, they had volumetric capacity in 3-4 times smaller, than other tested materials. The discharge curve is shown on Figure 5. 

The thermally expanded graphite was used without any preliminary treatment the carbon was synthesized by carbonation of the raw material in an argon flow at 500°C with subsequent thermal treatment. Carbon residues strongly differing in the crystallinity degree were obtained as depends on the temperature which ranged from 500°C to 1300°C. The identity of each material was checked by X-ray spectroscopy. 

The source carbon materials show a significant electrochemical activity for lithium intercalation though the reversible capacity is relatively low and tends to reduce with cycling. For the thermally expanded graphite... 

One of possible ways of improving the specific characteristics of LIB electrodes is the use of thermally expanded graphites (TEG) as electrically conductive additives of positive active mass. The efficiency of TEG s use may be illustrated by analyzing a simple theoretical model proposed by us AM - electrically conductive additive (Figure 4). 

Thermally expanded graphite is, in principle, one of the most efficient conductive additives to various battery active materials, first of all... 

The composite as a unique material normally refers to hybrid or mixed materials between dispersed filler or reinforcemenf in fhe form of fiber, powder, flake, etc. and the continuous matrix. The composite applied to manufacture the plate mainly belongs to the type of nonmefallic composite with both nonmetallic filler and mafrix, alfhough research work on composite plates with metal filler has been carried ouf. This research will not be specifically introduced here because no promising results have been reported so far. The other sandwiched composite plate consists of layered metals and thermal expanded graphite and was developed by Russian scientists [11] however, no technical details were released. 

In order to improve intumescence and fire protection, the effect of introduced thermal expanded graphite (TEG), which served as filler, on coke formation and physical and mechanical characteristics of die coatings, was also studied in the chapter. 

Introduction of the modifying additive PEDA in combination with a filler - thermal expanded graphite - permits to increase the coating intumescence by 11 times, resulting in improved fire and heat protective properties of the coatings and reduced destmction of fiberglass plastic. 

Yakovlev AV, Finaenov AI, Zabud kov SL, Yakovleva EV. Thermally expanded graphite synthesis, properties, and prospects for use. Russ J Appl Chem 2006 79(11) 1741-51. 

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