NOVELTY - The heat sink (10) has two plates (11,12), and cooling pins (13) arranged between two plates in a two-dimensional grid (G). The diameter (DF) of each cooling pin of at least a subset of the cooling pins measured in a main flow direction (MFD) of coolant is greater than the diameter (DP) of cooling pins perpendicular to the main flow direction of coolant.    USE - Heat sink used in battery cell assembly of vehicle (all claimed) for transferring heat from battery cell to coolant.    ADVANTAGE - Obtains good ratio of heat transmission to required pumping power since cooling pins are exposed sufficiently to the coolant flow to allow good heat transmission without constituting unnecessary great resistance to the coolant flow. Obtains improved contact between coolant and cooling pins since repeated alternation of passages and cooling pins in main flow direction causes repeated split of streamlines of coolant during travel through the heat sink. The optimized combination of dimensions of pins and mutual arrangement of neighboring pins are reused to allow optimal efficiency of heat transmission of the heat sink. Prevents turbulences that increase the flow resistance of heat sink without improving heat transfer between the heat sink and coolant since streamlines of coolant can keep running in parallel to the plates. The heat sink has better overall efficiency of heat transfer since special shape and special geometrical arrangement of the cooling pins of heat sink allows that streamlines come into contact with the cooling pins without causing strong turbulences. Obtains increased thermal performance by 12 percent, decrease in maximal temperature by 1.3 degrees Celsius, increased mechanical performance by 1.3 percent and reduction in weight by 23 percent.    DESCRIPTION OF DRAWING(S) - The drawings show the perspective view of a heat sink and schematic diagram of the geometry of heat sink.    Heat sink (10)    Plates (11,12)    Cooling pins (13)    Diameter (DF)    Diameter (DP)    Two-dimensional grid (G)    Main flow direction (MFD)