Battery cell of a battery cell assembly of battery cells, and use of multiple cells

Battery cell (2) of a battery, particularly a lithium-ion battery, said cell (2) having a longitudinal axis and a heat-conductive, extending in the longitudinal direction and the cell (2) comprising casing (7), characterized in that the sheath (7) is a sleeve, the wall thickness in the circumferential direction varies strongly with several circumferentially spaced thickened portions with corner areas.