Patent ID: 8389148

Claim:
A cylindrical battery separator constituting a semi-final, intermediate unit configured to be inserted in a cathode cavity of a cylindrical battery, said cylindrical battery separator comprising: a cylindrical body having a vertical circumferential wall defined by a plurality of layers formed by winding at least one non-woven, continuous sheet material in a plurality of turns to obtain a layered structure, wherein no binder is applied between the layers, and said layers of the vertical circumferential wall are not fused together, whereby the full vertical circumferential surface is active; and a curved and bent closed bottom part constituting an end of said cylindrical body, wherein said bottom part is an integral extension of said cylindrical body, wherein said bottom part is comprised of layers having a uniform and evenly bent shape along an entire circumferential section of the cylindrical body which are fused together by heat such that said layers of the bottom part are held together, and wherein said bottom part has respective essentially wrinkle-free continuous inner and outer surfaces free of any bulging and a substantially uniform thickness.