Battery Module Having Cooling Structure Using Insulating Oil, and Battery Pack and Vehicle Comprising Same

A battery module comprises a cell stack assembly, a front bus bar frame, and a rear bus bar frame. The cell stack assembly includes a plurality of battery cells and a plurality of fluid passage spacers located between adjacent battery cells. The front bus bar frame assembly is coupled to a side of the cell stack assembly along a longitudinal direction and includes a module inlet through which insulating oil for cooling of the plurality of battery cells is supplied to the plurality of fluid passage spacers. The rear bus bar frame assembly is coupled to the opposite side of the cell stack assembly along the longitudinal direction and includes a module outlet through which insulating oil passing through the module inlet and the plurality of fluid passage spacers is discharged.