Polymer/salt hybrids ionic conductivity

The ionic conductivity of these polymer/salt hybrids was evaluated after the polymers were thoroughly dried under vacuum (Fig. 12a). These polymers showed... 

Figure 12 (a) Temperature dependence of ionic conductivity, (b) VFT plots for polymer/salt hybrids 10. 

Table 6 Glass Transition Temperature, Ionic Conductivity and VFT Parameters For Polymer/Salt Hybrids 10...

Ambient temperature molten salt can be obtained by several methods. One effective way to obtain a room-temperature molten salt is by the introduction of polyether chains to ions. The term polyether/salt hybrid is used in this chapter as a common name for polyether oligomers having anionic or cationic charge(s) on the chain (Figure 22.1). Polyethers, such as poly-(ethylene oxide) (PEO), are known as representative ion conductive polymers [1]. Polyether/salt hybrids have been studied as a kind of room-temperature molten salt apart from the development of onium-type ionic liquids [2]. The preparation of ionic liquids consisting of metal ions has been one of the important goals in this research field. Polyether/salt hybrid derivatives give one such solution for this task. 

On the other hand, we have reported the preparation of gel-type polymer electrolytes using polyether/salt hybrid oligomers [12]. A network-type PPO film was swollen with the PPO/triiluoromethylsulfonamide Uthium salt hybrid. The obtained gel containing 50 wt% of PPO/salt hybrid showed a low Tg of —62°C. The PPO/salt hybrid behaved as not only an added salt but also a plasticizer. The ionic conductivity was over 10 S cm at room temperature. Furthermore this gel electrolyte showed a favorable lithium-ion transference number of 0.7-0.8. 

Novel MEEP-type polyphosphazene-silicate hybrid network membranes (Tg —38 to 67 °C), exhibiting high ionic conductivities with lithium bis(trifluoromethane-sulfonyl)imide (LiTFSI) as the salt, have been prepared as candidates for dimensionally stable solid polymer electrolytes by a designed sequence of steps starting from [NPCl2] and involving the incorporation and hydrolysis of triethoxysilane groups (Scheme 15). ... 

Ionic conductivity studies in PMMA-PEO hybrid polymer electrolytes with lithium salts. J. Power Sources, 96, 406 10. 

The conductivity isotherms derived from conductivity measurements revealed the presence of a maximum conductivity for the electrolyte system located in the composition interval 8 < n < 10. Ionic conductivity in this hybrid electrolyte increases gradually with salt content for compositions with n > 10. This parameter is generally expected to increase with the number of charge carriers, up to a limit found at about n = 8. Further increase in salt content beyond this concentration resulted in a decrease in total ionic conductivity. This observation can be explained by the formation of associated ionic species (e.g. contact ion pairs, triplets or higher multi-plets or ultimately ion aggregates) and an increased tendency for ions to form bridging interactions between adjacent polymer chains a process... 

---