A separating member for separating a plurality of battery cells is provided, which includes a plurality of first walls and a plurality of second walls having a thickness larger than a thickness of the first walls. The separating member is expandable from a collapsed state to an expanded state. The separating member has a plate configuration in the collapsed state and has a honeycomb structure in the expanded state. The plurality of first walls and the plurality of second walls jointly define a plurality of cell units of the honeycomb structure.