Carbon Nanofibers from Electrospinning – A Promising Electrode Material for Energy Storage and Conversion SciDoc Publishers | Open Access | Science Journals | Media Partners

Innovative energy conversion and storage systems, e.g. rechargeable lithium ion batteries (LIBs), supercapacitors, solar cells, and fuel cells, are urgently demanded to meet increasing energy needs of modern society to fulfill newly emerging electric applications such as portable electronics, electric vehicles, and industrial power management [1]. The performance of these devices depends predominantly on the properties of their electrode materials. Carbon/graphite has been widely employed as electrode material because of its good chemical stability, thermal stability, and electrical conductivity. With recently widespread interest in nanomaterials, carbon nanotubes have been extensively used as component for both anode and cathode materials in energy conversion and storage systems because they possess not only common advantages of carbon but also high specific surface area and better charge transport properties [2, 3]. However, carbon nanotubes often require delicate purification process to remove residue metal catalyst, which may have significant adverse effect on their electrochemical performance. In recent years, making carbon fibers with diameters fall into submicron and nanometer range (termed as carbon nanofibers) has attracted growing attention. The production of carbon nanofibers falls into two categories: vapor growth and spinning. The approach of vapor phase growth, i.e. catalytic synthesis, has been investigated [4-6] and graphitic carbon nanofibers are grown from carbon-containing gases by using metallic catalysts. Nonetheless, similar as carbon nanotubes, the carbon nanofibers from vapor growth are relatively short and difficult to be aligned, assembled, and processed into applications, not to mention their low product yield, expensive manufacturing equipment, and significant amount of catalyst residue. As a comparison, the rapidly developing technique of electrospinning provides a straightforward way to make continuous carbon fibers at nanometer scale (typically 50 – 500 nm). Similar as conventional carbon fiber production, polyacrylonitrile (PAN) is the most often used precursor polymer for carbon nanofibers from electrospinning while other approaches are also available such as carbon nanofibers from carbide and lignin [7, 8]. Driven by electrical force, the carbon precursor solution is ejected from spinneret during electrospinning and follows a binding, winding, spiraling and looping path in three dimensions and the jet in each loop grows longer and thinner, which is termed as “bending instability” [9-12]. With the evaporation of solvent,