A battery module , comprising a case, a plurality of secondary batteries that comprise pressure relief elements and are disposed in the case, and a cover configured to connect to the case, wherein the pressure relief element is structured to deform in response to an increasing internal pressure in the secondary battery until the pressure relief element bursts, and the secondary battery can expel high temperature particles through the burst pressure relief element , characterized in that the cover comprises a cover body and a protection assembly , wherein the protection assembly and the cover body are stacked; and the protection assembly comprises: a particle-blocking layer comprising a receiving side for receiving the high temperature particles and a connecting side opposite to the receiving side, wherein the particle-blocking layer comprises a plurality of particle-blocking units in a concave-convex arrangement, and the particle-blocking unit can block the high temperature particles; and a separate protective layer disposed at the connecting side of the particle-blocking layer and connected to the particle-blocking layer , wherein the particle-blocking layer comprises a sheet body and a plurality of protrusions protruding from a surface of the body in its thickness direction and spaced apart from each other, each particle-blocking unit comprises two adjacent protrusions and a concave between the two adjacent protrusions , the separate protective layer is disposed on a surface of the body away from the protrusions , and the two adjacent protrusions in the particle-blocking layer satisfy a relation , 0.005 ≤ d / D − d ≤ 5 wherein the two adjacent protrusions each has a projection on the surface of the body , and a straight connecting line between respective central points of the two adjacent protrusions in the projections is denoted as H, and wherein in the relation , d refers to a dimension from a central point of one of the two adjacent protrusions in the projection to its own edge in the projection along the straight connecting line, and D refers to a dimension from a central point of one of the two adjacent protrusions in the projection to an edge of the other protrusion in the projection along the straight connecting line. a particle-blocking layer comprising a receiving side for receiving the high temperature particles and a connecting side opposite to the receiving side, wherein the particle-blocking layer comprises a plurality of particle-blocking units in a concave-convex arrangement, and the particle-blocking unit can block the high temperature particles; and a separate protective layer disposed at the connecting side of the particle-blocking layer and connected to the particle-blocking layer , wherein the particle-blocking layer comprises a sheet body and a plurality of protrusions protruding from a surface of the body in its thickness direction and spaced apart from each other, each particle-blocking unit comprises two adjacent protrusions and a concave between the two adjacent protrusions , the separate protective layer is disposed on a surface of the body away from the protrusions , and the two adjacent protrusions in the particle-blocking layer satisfy a relation , 0.005 ≤ d / D − d ≤ 5 wherein the two adjacent protrusions each has a projection on the surface of the body , and a straight connecting line between respective central points of the two adjacent protrusions in the projections is denoted as H, and wherein in the relation , d refers to a dimension from a central point of one of the two adjacent protrusions in the projection to its own edge in the projection along the straight connecting line, and D refers to a dimension from a central point of one of the two adjacent protrusions in the projection to an edge of the other protrusion in the projection along the straight connecting line. <EOS>