Polyacetylene electrodes

The heterojunctions of the polyacetylene were realized not only with inorganic photoconductors but also with organic polymers [139]. The results obtained show good similarity with barrier and heterojunction characteristics for inorganic semiconductors. Photoelectrochemical cell for solar energy conversion with polyacetylene electrodes and Na2S, electrolyte had an efficiency of 1 % at 2.4 eV [140], The complicated phenomena take place at the electrodeelectrolyte interface. 

McDiarmid s group has put a great deal of effort into rechargeable (secondary) polyacetylene batteries599. Several different configurations have been tested. As set out in table 4, cells can be constructed with two polyacetylene electrodes, both p-type, both n-type, one of each, or either form against lithium metal. 

Fig. 4.116. Experimental apparatus used by Shirakawa et al. for photoelectrochemical measurements of a polyacetylene electrode (H. Shinal wa, S. Ikeda, M. Aizawa, J. Yoshitake, and...

An interesting composite material has been prepared by the electropolymerization of pyrrole on polyacetylene electrodes (45). Because oxidized polypyrrole is far more stable in air than polyacetylene, the resulting composite has the stability of polypyrrole. With different synthetic conditions, either a thin layer of polypyrrole was deposited over individual fibrils of the polyacetylene film or a dense polypyrrole film coated the entire film. When the dense polypyrrole film covered the entire polyacetylene film, the interior... 

The organic solvents currently used the most, tetrahydrofuran and propylene carbonate, have clear limitations in regards to stability [70-73]. The potential at which p-doping (indififiision of negative ions) of polyacetylene electrode occurs is close to the anodic limit for propylene carbonate and higher than the limit for tetrahydrofuran. Thus one of the major problems with polymeric batteries is the problem of slow electrochemical breakdown of organic solvents at actual doping potentials. 

While it is possible that future polymeric batteries will be all-polymeric solid-state batteries, it is predicted, however, that the most promising solid state batteries will combine polymeric electrolytes with nonpolymeric electrode materials such as TiS2, VeOis, Li or LiAl, the specific capacity of which surpasses that of polyacetylene electrodes. 

Farrington, G.G., and R. Huq. 1985. Polyacetylene electrodes for non-aqueous lithium batteries. 7 Power Sources 14 3. 

Nagatomo, T., G. Ichikawa, and O. Omoto. 1987. All-plastic batteries with polyacetylene electrodes. 7 Electrochem Soc 134 (2) 305. 

MacDiarmid, A.G., et al. 1984. Fuel cells and batteries employing polyacetylene electrodes in aqueous electrolytes. Energy Tech 11 577. 

The electrochemical polymerization method was used to prepare layers of conductive polymers on electrodes pre-coated with another conductive polymer or using films of a conductive polymer as electrode. This was the method used to prepare a composite of poly acetylene and polypyrrole [150,151] A sandwichlike composite with layers of polypyrrole adhered to polyacetylene was obtained using undoped polyacetylene electrodes. The use of doped polyacetylene induced pyrrole polymerization in the bulk of the film. A strong improvement in the stability of polyacetylene was observed exposure to ambient temperature of 30 days or to water for 20 minutes did not reduce the conductivity of both materials. 

Table 14 The electrical potentials of rare earth polyacetylene electrodes. ...

Figure 19. Experimental apparatus used by Shirakawa for photoelectrochemical measurements of a polyacetylene electrode.

Figure 20. Cathodic current derived from a trans polyacetylene electrode in the dark and on illumination.

A number of other battery types have been published (54) by MacDiarmid, for example, a dual polyacetylene electrode battery has been described in which there is a pCCH) cathode and an n-(CH)x anode in 1 M LiClO with the solvent being propylene carbonate or sulfolane. 

Fritz Will has made a study of discharge behavior of polyacetylene electrodes (56) and has drawn attention to the fact that slow dopant diffusion and slow discharge at the polymer/electrolyte interface is the principal problem. No steady state potentials were obtained over about 1 hour. This work quantitates some of the difficulties with these batteries. 

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