Effect of solvent on thermal transitions and conductivity of poly (vinylidene fluoride) gel electrolytes.

The melting (Tm) and crystallization (Tc) temperature increased with increasing solvent phenyl propanol (PhP) concentration in the mixture of solvent propylene carbonate and phenyl propanol (PC/PhP). It is also a little enhances of Tm and Tc with adding ethylene carbonate (EC) to propylene carbonate (PC). The melting (Tm) and softening temperature (Tsoft) follows the following order of solvents PC<EC:PC<PhP:PC. There was a small change of modulus was observed with the addition of PhP. The conductivity falls with increasing PhP concentration and viscosity and re-calculate free ion concentration. The adding EC to PC raises temperatures slightly, but conductivity much the same. The overall, adding poorer solvent PhP increases the melting and crystallization temperatures at the expense of conductivity, but a little changes was observed in storage modulus, much better gel network, thereby securing the continuity of the complex leads to more flexible ductile and crystalline phase serves better mechanical properties. The crystallinity of PVDF gel electrolyte is about 50%, which facilitate to changes gel network structure slightly with PhP concentration. The formation of fully interconnected three dimensional frame work structure uniformly distributed pores with large surface area can function as efficient channels for ion conduction. The above graph shows the conductivity of samples with varying PhP percentage of solvent for gel electrolyte on PC:PhP LiBF4 1M PVDF 30%. The addition of PhP solvent concentration up to 36% in the PC solvent mixture increases both gel melting and gelation temperatures on the expense of conductivity falls but remain at 10−3 order. But there was viscosities of electrolyte mixtures increases and no change in modulus was observed. [ABSTRACT FROM AUTHOR]