Electric separator, method for making same and use thereof in high-power lithium cells

Abstract

The present invention relates to electrical separators and to a process for producing them. An electrical separator is a separator used in batteries and other arrangements in which electrodes have to be separated from each other while maintaining ion conductivity for example. The separator is preferably a thin porous insulating material processing high ion perviousness, good mechanical strength and long-term stability to the chemicals and solvents used in the system, for example in the electrolyte of the battery. In batteries, the separator shall fully electrically insulate the cathode from the anode. Moreover, the separator shall be permanently elastic and follow movements in the system, for example in the electrode pack in the course of charging and discharging. This object is achieved by an electrical separator according to the invention, comprising a sheetlike flexible substrate having a multiplicity of openings and having a coating on and in said substrate, said substrate being a polymeric nonwoven and said coating being a porous electrically insulating ceramic coating, said separator being characterized by said nonwoven having a thickness of less than 30 μm, a porosity of more than 50% and a pore radius distribution in which at least 50% of the pores have a pore radius from 75 to 150 μm.