5/26/2023 0 Comments Carbon paper![]() The diameter of fibrous carbons obtained through this method is usually several tens of nanometers to several hundred nanometers, so the fibers are usually called carbon nanofibers (CNFs). (19) By using this method, fibrous carbons can be continuously produced but the diameters of the carbons through this method tend to be larger than those of CNTs. They contribute to the formation of primary fibrous carbons, and then carbon layers are deposited on the catalytically formed primary fibrous carbons through thermal deposition of the carbon source. These metal atoms aggregate and form metal nanoparticles. The precursor is heated in the reactor and decomposes, releasing numerous metal atoms. To prepare such fibrous carbons, a modified CVD method has been developed, where the precursor of metal nanoparticles, usually an organometallic complex like ferrocene, is continuously provided along with the carbon source into the reactor. ![]() Therefore, papers constructed from fibrous carbons with such a highly aligned crystal structure and with a small diameter are preferable for various applications. Because carbon fibers obtained from such fibrous polymers without heat treatment generally have an amorphous structure or a turbostratic structure, (11, 12) their electrical conductivity is considered not to be as high as that of carbons composed of highly aligned graphene sheets. Through this method, fibers having diameters from several micrometers to less than 100 nanometers can be obtained (8-10) and such fibers can be easily casted into a paper. As a potential method to produce fibrous carbon precursors with a smaller diameter, the electrospinning method is known. (6, 7) As the surface area of such carbon papers depends on the diameter of the fibers composing it, it is difficult to increase the surface area when the diameter of the fibers is large. In a typical preparation process of commercially available carbon papers, fibrous precursor polymers, whose diameters are several micrometers, are casted or woven into a paper and then the polymer paper is carbonized at a high temperature. (1-5) When they are used in lithium–air batteries, they are generally coated with porous carbons using a binder, because their surface area is too small for surface reactions such as Li 2O 2 deposition to significantly proceed. Hence, they are often used as current collectors for the latest energy storage/conversion systems, such as fuel cells and lithium–air batteries. In electrochemical experiments conducted to evaluate the performance of LPI-CNF(20) paper as a cathode, the paper showed a larger discharge capacity on the basis of the cathode weight than a conventional cathode (a commercially available carbon paper combined with a porous carbon), which indicated that it has a high potential to be used as a cathode in lithium–air batteries.Ĭarbon papers (CPs) formed from carbon fibers (CFs) have several unique properties, such as a high electrical conductivity, a high mechanical strength, high gas permeability, and high chemical resistance. These properties are required for cathodes in the latest battery systems such as lithium–air batteries. LPI-CNF(20) paper also had a high surface area and showed a high electrical conductivity and a moderate gas permeability according to its void size. The paper prepared from the CNFs with an average diameter of 20 nm (LPI-CNF(20) paper) was firm and flexible even though it was prepared without using any binders. ![]() Carbon paper was made from the CNFs through a simple filtration process. To improve the performance of carbon paper used for applications such as electrodes for electrochemical devices and air filters, two types of long carbon nanofibers (CNFs) with average diameters of 20 and 49 nm were prepared by the liquid pulse injection (LPI) technique by adjusting reaction conditions.
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