Secondary lithium cell: Separators compatible with electrolyte solution based on cyclic esters

To overcome the incompatibility between microporous polypropylene separator and electrolyte solutions based on cyclic esters, three methods of preliminary impregnation of the separator with electrolyte solution, without using surface active agents, are investigated. Values of the specific resistance of the separator, measured in 1M solutions of lithium salts in propylene carbonate, depending on the method of preliminary treatment, are obtained. Experimental data from the tests of secondary lithium button cells supplied with pretreated separators are presented. It is concluded that the pretreatment methods discussed can be used successfully. The best results are obtained by thermal pretreatment with the basic solvent.