Polymer Electrolyte Based on Poly(ethylene imine) and Lithium Salts.

The dissolution of lithium salts in linear polyethylene imine has been investigated because of its possible role as a solid electrolyte in lithium batteries. Lithium salts included in the study are LiF, LiCl, LiBr, LiI, LiSCN, LiCl104 and LiBF4. When cast from solution in a common solvent, a uniform mixture is obtained expect for the case of LiF. Interaction of the salt and polymer can be characterized by observing a loss in crystallinity of the polymer and an increase in the glass transition temperature. At concentrations of salt below 10 mole percent, the polymer can slowly recrystallize at room temperature but at higher concentrations, the mixture remains amorphous for an indefinite period of time. DC conductivity at room temperature is about .0000001 Scm but increases to .001 Scm at 150 C. Author