Preparation And Capacitance Characterization Of Carbon Electrode Materials

Electrode materials for electric double layer capacitors(EDLC) have been extensively developed due to the increasing demand for a new kind of accumulators of electrical energy with a high specific power and a long durability. Because of CSs have higher tap density, a larger amount of electrode material can be loaded on electrodes such that a higher volumetric energy density can be achieved. In addition, the initial irreversible capacity loss that arises from the formation of a passivation layer on the cabon surface can be minimized due to a smaller surface area inherent from their spherical shape.In the first chapter, we explained the basic theory of EDLC, carbon matterials and its research status. We also prospect its application.We first prepared nano carbon spheres by hydrothermal method, through its XRD, SEM, FT-IR, we know that this kind of nanocomposites is not crystallized graphite, but low molecular polymer. Meanwhile, the functional groups have a great help for biomedical applications areas. At the same time, we discussed the role of the different conditions influence the synthesis of the matterials. We got the results that it had the best morphology on the 180℃,8hand no less than the concentration of 0.5M. This discovery has significant impact for practical applications, in practice, we can change the the different conditions to influence the morphology of the carbon matterials.Then we used the nano carbon sphere to prepared the crystallized carbon materials. For the nano carbon sphere we have synthezed is a low molecular polymer, we have to use a physical head-tread method to reach the translation. The SEM supposed that the morphology after head-tread is not changed, and the XRD is a fair evidence to support the possible presence of an amorphous carbon phase within the carbon spheres。In order to apply the EDLC to various practical devices, even to electric vehicles, the development of EDLC with both high power density and high energy density is needed. The key factors limiting the power density and energy density of EDLC include the internal resistivity of the electrode itself, the resistivity between the electrode and current collector and the resistivity of the electrolyte.In order to solve the problem, we report here an integrated electrode which the CS layer directly growed on the Ni foam prepared by the hydrothermal technique, which takes the advantages of low cost, low environmental load, simple equipment and suitability for mass production. In addition, this technique allows for flexibility in shape and size of the substrates. Finally, Direct growth without any adhesive, can significantly reduce the resistance between electrode materials and nickel foam. The EDLC built from such electrodes has exhibited a near-ideal rectangular cyclic voltammograms, an indication of a small ESR. All of these make a highly attractive route in fabricating CS electrodes for high performance EDLC and other similar devices.