Electronic conductive agents

However, Li2MnSi04 suffers from poor cycle life, which is most likely caused by Jahn-TeUer distortion and loss of crystallinity during cycling. In addition, these materials also suffer from poor electronic conductivity and the consequent slow reaction kinetics. Therefore, various synthetic routes such as sol-gel and microwave-solvothermal methods have been employed to prepare nanostractured materials, and coating with electronically conductive agents has been carried out to improve their electrochemical performance [127-129]. 

Negative and positive electrode materials, electrolytes, and separators are four key components for lithium-ion batteries. However, other auxiliary materials such as electronic conductive agents, binders, solvents for slurry preparation, positive thermal coefficient (PTC) materials, current collectors, and cases are also important in the production of complete lithium-ion batteries. 

Other carbon materials such as carbon nanotubes (CNTs), carbon nanofibers, and graphene can also be used as conductive agents. CNTs have been discussed in Chapter 7, and will not be discussed again. The electronic conductivity of CNTs is better than that of acetylene black, UFC, and copper. Theoretically, CNTs can carry an electric current density of 4 x 10 A/cm, which is more than 1000 times greater than that of metals such as copper. There are several companies all over the world that manufacture CNTs. Transmission electron micrographs (TEMs) of some typical commercial products, which are widely used as electronic conductive agents, are shown... 

To reduce the formation of carbon deposited on the anode side [2], MgO and Ce02 were selected as a modification agent of Ni-YSZ anodic catalyst for the co-generation of syngas and electricity in the SOFC system. It was considered that Ni provides the catalytic activity for the catalytic reforming and electronic conductivity for electrode, and YSZ provides ionic conductivity and a thermal expansion matched with the YSZ electrolyte. 

All of the following ejqperiments were conducted with the photocatalyst and electron transfer agent in the reactor. 

Mao et al. [174] recently presented research in which Nafion ionomer particles were used as hyperdispersant agents in the MPL of a cathode DL. It was shown that this ionomer helps to decrease the particle size of the PTFE in the MPL. Thus, increasing the Nafion particle content gradually decreased the PTFE size and decreased the hydrophobicity in the layer. In fuel cell testing, an MPL having 1 wt% ionomer showed the best performance it improved the gas permeability and electronic conductivity. 

Polymers that display electronic conductivity are usually insulators in the pure state but, when reacted with an oxidizing or reducing agent, can be converted into polymer salts with electrical conductivities comparable to metals. Some of these polymers are listed in Figure 6.38, along with the conductivities of metals and ceramics for... 

Schmidt KH, Flan P, Bartels DM (1995) Radiolytic yields of the hydrated electron from transient conductivity improved calculation of the hydrated electron diffusion coefficient and analysis of some diffusion-limited (e )aq reaction rates. J Phys Chem 99 10530-10539 Schoneich C, Aced A, Asmus K-D (1991) Halogenated peroxyl radicals as two-electron-transfer agents. Oxidation of organic sulfides to sulfoxides. J Am Chem Soc 113 375-376 Schuchmann Fl-P, von Sonntag C (1981) Photolysis at 185 nm of dimethyl ether in aqueous solution Involvement of the hydroxymethyl radical. J Photochem 16 289-295 Schuchmann Fl-P, von Sonntag C (1984) Methylperoxyl radicals a study ofthey-radiolysis of methane in oxygenated aqueous solutions. Z Naturforsch 39b 217-221 Schuchmann Fl-P, von Sonntag C (1997) Heteroatom peroxyl radicals. In Alfassi ZB (ed) Peroxyl radicals. Wiley, Chichester, pp 439-455... 

Two hidden assumptions implicit in the model of Sato and Mooney (1960) are (1) that the conductor consists of a single phase, such as graphite or pyrite and (2) that oxidation of the conductor would result in its conversion to a non-conductive phase. Thomber (1975a, 1975b) presents a reactive conductor model in which the conductor itself is the reducing agent, which is in apparent contrast to the model of Sato and Mooney. However, the reactive conductor model is based on the presence of one oxidised phase and at least one reduced phase relative to the first phase, all of which are electronically conductive. Such scenarios have been noted in terrain with deep weathering profiles due to the phase conversion of reduced sulphide minerals to more oxidised forms. 

The essential ingredients of the catalyst layer are an electronically conducting matrix of carbon grains, Pt catalyst particles supported on carbon and a protonconducting network of well-humidified PFSI. In addition, Teflon (PTFE) may be added as a binder and hydrophobizing agent. 

Two different blends, EPDM/polyacetylene and Kraton/polyacetylene have been prepared by various blending techniques. The characterization of two blends have been carried out by IR, X-ray and electron microscopic studies. Upon doping of the blends with various electron accepting agents, such as It and FeCl., conductivities of the blends were found to be in the range of 10 - 100Q-lcm l. 

The properties of (CFJ vary with x electronic conductivity and heat of immersion (wetting agent, butanol) decrease with increasing x, and the color changes from black for X < 0.715 grey to white for x > 0.998 . On the other hand, the frequency of the C—F stretch is nearly independent of x. In poly(monocarbon monofluoride) the fluorine atoms form layers above and below puckered layers of sp -hybridized carbon atoms . 

Electrochemical methods have played an important role in the recognition of cation radicals as intermediates in organic chemistry and in the study of their properties. An electrode is fundamentally an electron-transfer agent so that, given the proper solvent system, anodic oxidation allows formation of the cation radical without any associated proton or other atom transfer and without the formation of a reduced form in the immediate vicinity of the cation radical. Moreover, because the potential of the electrode can be adjusted precisely, its oxidizing power can be controlled, and further oxidation of the cation radical can often be avoided. Finally, the electrochemical experiment can involve both production of the cation radical and an analysis of its behavior, so that information about the thermodynamics of its formation and the kinetics of its reaction can be obtained, even if the cation radical lifetime is as short as a few milliseconds. There are some limitations, however, in the anodic production of cation radicals. The choice of solvent is limited to those that show reasonable conductivity with a supporting electrolyte (e.g. tetra-n-butylammonium perchlorate, TBAP). Acetonitrile, methylene chloride and nitrobenzene have been employed as solvents, but other favorites, such as benzene and cyclohexane, cannot be used. The relatively high dielectric constant of the suitable... 

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