The present invention relates to a battery cell assembly in which a plurality of electrically-connected battery cells are stacked, and a battery module including same. The battery cells are mounted in cell housing members, with both sides of the battery cells, excluding electrode terminals, wrapped in units of one or more battery cells. An expansion opening part for exposing a part of the main body of each of the battery cells to the outside of each of the cell housing members during expansion of the battery cells is formed on one side or both sides of each of at least two cell housing members, and the battery cells are stacked so that at least two expansion opening parts face each other.