NOVELTY - A heat sink (110) for an electrochemical cell (120) comprises a cell region (112); a connecting region (116) for mechanical and thermal coupling to a cooling plate (130); and a fold region (114) between the cell and connecting regions, consisting of a flexible fold in the heat sink.    USE - The heat sink is specifically part of a lithium ion cell assembly having an integrated cooling element; and can be bonded to the cooling plate (e.g. a cooling plate containing circulating fluid) in force-fited and/or material-bonded manner. The lithium ion cell assembly is typically a multi-cell assembly for powering devices with high energy requirement, such as electric or hybrid vehicles.    ADVANTAGE - The flexible fold region of the heat sink allows mechanical bonding of the heat sink to the cooling plate to be separated from the corresponding thermal contact, thus (i) improving the thermal contact between the heat sink and cooling plate, (ii) reducing mechanical stress on the thermal contact and (iii) allowing subsequent breakage of the bond (for cell exchange) without thermally damaging the cell. In the case of material-bonded connection between the heat sink and cooling plate, heat transfer across the connection is optimized without thermal damage to the cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method for connecting a heat sink (110) (as described above) for an electrochemical cell (120) to a cooling plate (130), involving (a) introducing the connecting region (116) of the heat sink into a receiving through-hole in the cooling plate until the fold region (114) of the heat sink lies on the cooling plate, (b) applying a compressive force (F) (acting in the direction of the cooling plate) onto the heat sink to fix the heat sink in the hole; and (c) introducing a fixing element (140) into the hole from the side of the plate opposite from the fold region, so that the connecting region is force-fitted onto the cooling plate; and    (2) a cell device comprising heat sink(s) (110) as above; electrochemical cell(s) (120), coupled with the cell region(s) (112) of the heat sink(s); and a cooling plate (130) with through-hole(s) for receiving the connecting region(s) of the heat sink(s), the cooling plate being mechanically and thermally bonded to the connecting region(s) of the heat sink(s).    DESCRIPTION OF DRAWING(S) - The figure shows a sectioned view of an electrochemical cell device, incorporating a heat sink.    Cell device (100)    Heat sink (110)    Cell region, for coupling to electrochemical cell (112)    Flexible intermediate fold region (114)    Region for mechanical and thermal coupling to cooling plate (116)    Pressure region (118)    Electrochemical cell (120)    Cooling plate (130)    Fixing element (140)    Compressive force application direction (F)