Battery Module

A battery module for improving heat balance of a cell assembly provided in the battery module includes a cell assembly having at least three battery cells stacked along a stacking axis such that at least one battery cell located at an interior position within the cell assembly along the stacking axis has a greater thickness along the stacking axis than a battery cell located at an outer side of the cell assembly. A module housing includes at least one sidewall and is configured to accommodate the cell assembly in an inner space defined by the sidewall.