Dopable polymers

Figure 9 shows the discharge curves of a Type I polypyrrole-based, a Type II polypyrrole/poly(3-methylthiophene)-based and a Type III poly(dithieno[3,4-6 3, 4 -d]thiophene-based supercapacitor at 4 mA cm discharge current. Types I and II can be assembled using such conventional heterocyclic polymers as polypyrrole, polyaniline and polythiophene, which are efficiently p-dopable polymers and can easily be chemically or electrochemically synthesized from inexpensive... 

A battery cell where both the electrodes consist of dopable polymer is shown in Figure 5.23. The electrolyte in this case consists of Li+ClO 4 dissolved in an inert organic solvent, usually tetrahydro-furan or propylene carbonate. When two sheets of polyacetylene or PPP are separated by an insulating film of polycarbonate saturated in an electrolyte (lithium perchlorate), and completely encapsulated in a plastic casing, a plastic battery can be made. The two sheets of polyacetylene or PPP act as both anode and cathode for the battery. A schematic is shown in Figure 5.24. Although doped polyacetylene and polyaniline electrodes have been developed, polypyrrole-salt films are the most promising for practical appKcation. 

It is also possible for only one electrode to consist of dopable polymer and for the other be of metal, usuaUy Kthium (Figure 5.25), which is preferred because of its low weight and high thermodynamic electrode potential. 

Loveday, D.C., M. Hmyene, and J.P. Ferraris. 1997. Synthesis and characterization of p- and n-dopable polymers. Electrochromic properties of poly-3-(p-trimethylammoniumphenyl)bithio-phene. Synth Met 84 245. 

Wudl and Heeger et al. prepared the self-dopable polymers poly(n-(3 -thienyl)alkanesulfonic acids) (P3TASH) and their sodium salts with alkane chain lengths ranging from 2 to 4 [127-129]. In an extension of this study, Ikenoue et al. found that poly(3-(3 -thienyl)propanesulfonic acid) (P3TPSH), which was obtained by exchanging the sodium ions in poly(sodium-3-(3 -thienyl)propanesulfonate) (P3TPSH) with protons... 

D. C. Loveday, A. A. Moxey, M. Hmyene, X. Ren, D. Guerrero, J. P. Ferraris, Characterization of self n-dopable polymers, Polymer Preprints (American Chemical Society, Division of Polymer Chemistry) 1998, 39, 145. 

Gottesfeld and co-workers at Los Alamos National Laboratory proposed in 1994 a classification of conducting polymer-based electrochemical capacitors as schematically presented in Figure 15.6 [11], The first one is a symmetrical capacitor which involves the same p-dopable polymer for both electrodes and was called the Type I capacitor. Polypyrrole [11, 37, 47] and polyaniline [48] were commonly used as active electrode materials for the Type I capacitor. When the Type I capacitor is fully discharged, both electrodes are in a half-doped state. 

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