A system (1) for thermal management of battery cells in a battery system (2), such as a battery system for a charging station for electrical vehicles, the system (1) comprising a battery system (2) comprising a plurality of battery cell assemblies (3), each battery cell assembly (3) comprising a plurality of battery cells, and electrical circuitry (4) connecting the individual battery cell assemblies (3) of the plurality of battery cell assemblies (3). At least one battery cell assembly (3) of the plurality of battery cell assemblies (3) is provided with an extension element (7) configured to provide heat conduction from the battery cell assembly (3) to the exterior (12), and the at least one extension element (7) is arranged between a terminal (6) of the battery cell assembly (3) and the electrical circuitry (4) connected to the terminal (6) of the battery cell assembly (3).