A process for joining a battery element (49) by at least one polymer thread (28, 30), comprises the method steps: a) applying a web-shaped or sheet-shaped electrode material (16) to a first separator web (12), b) heating the at least one polymer thread (28, 30) above the softening temperature of the polymer material, c) introducing at least one polymer thread (28, 30) between the first separator web (12) and a further second separator web (40) to be applied to the first separator web (12), and d) cooling the at least one polymer thread (28, 30) between the separator webs (12, 40) and forming at least one material-bond compound (46, 48) therebetween.