Ionic conductivity polycations

Polycation-type ILs can provide an ion conductive path for the added salts. However, the bulk ionic conductivity of their polymers is very poor at present. It is necessary to improve their ionic conductivity for wide application. 

Figure 31.5 Arrhenius plots o1 the ionic conductivity for various polycation-type ILs P(xg TFSI).

Ionic conductivities of these polycation salts systems are shown in Figs. 23-25, which indicate higher ion conductivities than those of poly(ethylene oxide)-based polymers. The temperature dependence of the ionic conductivity for these polymers are also small in comparison with those of poly(ethylene oxide)-based polymers. Figure 26 summarizes the ion conductivities of these polycation-based SPE to compare their ion conductivities. 

Figure 26 Relation between content of polycations and ionic conductivity for molten salt-polycation complexes —o—, PBCl —o—, PBBr —A—PBACl —, PMVCl — —, PMVBr — A— PPyCl —A—, PPyBr — O — PBPCl —PSI.

The most desirable properties for electrically conductive polymeric materials are film-forming ability and thermal and electrical properties. These properties are conveniently attained by chemical modification of polymers such as polycation-7, 7,8, 8-tetracyanoqninodimethane (TCNQ) radical anion salt formation (1-3). However, a major drawback of such a system is the brittle nature of the films and their poor stability (4,5) resulting from the polymeric ionicity. In recent years, polymeric composites (6-8) comprising TCNQ salt dispersions in non-ionic polymer matrices have been found to have better properties. In addition, the range of conductivities desired can be controlled by adjusting the TCNQ salt concentration, and other physical properties can be modified by choosing an appropriate polymer matrix. Thus, the composite systems are expected to have important advantages for use in electronic devices. 

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