A battery pack, comprising a case and a battery module, the battery module being mounted within the case Wherein the battery module comprising: a plurality of battery cells, each of which comprising a first surface provided with an electrode terminal, a second surface opposite to the first surface, and side faces located between the first surface and the second surface; wherein the side faces comprise abutting faces and connecting faces connected with the abutting faces; and the plurality of battery cells are arranged in a length direction, and the abutting faces of all the battery cells face to each other; and a first spacer, at least part of which being arranged between the abutting faces of two adjacent battery cells, and fixed to the abutting faces of the two adjacent battery cells, wherein the first spacer is configured to fix to the case; the size of the first spacer is smaller than that of the abutting faces such there is a gap between the abutting faces of the two adjacent battery cells; wherein the first spacer comprises: a first spacing part, arranged between the abutting faces of the two adjacent battery cells and fixed to the abutting faces of the two adjacent battery cells; and a first connecting part, connected with the first spacing part, the first connecting part being located beyond the abutting faces of the two adjacent battery cells, and fixed to the connecting faces or the second surfaces of the two adjacent battery cells; wherein the length of the first connecting part is greater than that of each of the abutting faces, and a portion of the first connecting part located at an outer side of the abutting faces is provided with a connecting structure for fixation to the case; wherein the connecting structure comprises screw holes, a hole centre line of which is substantially parallel to a central line in a thickness direction of the first spacing part. a plurality of battery cells, each of which comprising a first surface provided with an electrode terminal, a second surface opposite to the first surface, and side faces located between the first surface and the second surface; wherein the side faces comprise abutting faces and connecting faces connected with the abutting faces; and the plurality of battery cells are arranged in a length direction, and the abutting faces of all the battery cells face to each other; and a first spacer, at least part of which being arranged between the abutting faces of two adjacent battery cells, and fixed to the abutting faces of the two adjacent battery cells, wherein the first spacer is configured to fix to the case; the size of the first spacer is smaller than that of the abutting faces such there is a gap between the abutting faces of the two adjacent battery cells; wherein the first spacer comprises: a first spacing part, arranged between the abutting faces of the two adjacent battery cells and fixed to the abutting faces of the two adjacent battery cells; and a first connecting part, connected with the first spacing part, the first connecting part being located beyond the abutting faces of the two adjacent battery cells, and fixed to the connecting faces or the second surfaces of the two adjacent battery cells; wherein the length of the first connecting part is greater than that of each of the abutting faces, and a portion of the first connecting part located at an outer side of the abutting faces is provided with a connecting structure for fixation to the case; wherein the connecting structure comprises screw holes, a hole centre line of which is substantially parallel to a central line in a thickness direction of the first spacing part. a first spacing part, arranged between the abutting faces of the two adjacent battery cells and fixed to the abutting faces of the two adjacent battery cells; and a first connecting part, connected with the first spacing part, the first connecting part being located beyond the abutting faces of the two adjacent battery cells, and fixed to the connecting faces or the second surfaces of the two adjacent battery cells; wherein the length of the first connecting part is greater than that of each of the abutting faces, and a portion of the first connecting part located at an outer side of the abutting faces is provided with a connecting structure for fixation to the case; wherein the connecting structure comprises screw holes, a hole centre line of which is substantially parallel to a central line in a thickness direction of the first spacing part.