A one-way valve for use in a battery module, comprising: a valve body comprising an inlet end and an exhaust end opposite to each other in an axial direction of the valve body and an airflow passage penetrating through the inlet end and the exhaust end, wherein the valve body is a columnar structure, the airflow passage comprises a first flow-passing hole and a second flow-passing hole distributed from the exhaust end to the inlet end, and the valve body further comprises a protrusion disposed on a bottom wall of the first flow-passing hole and extending towards the exhaust end, the second flow-passing hole penetrating through the protrusion; an elastic valve cap comprising a receiving concavity, the receiving concavity being a circular blind hole having a bottom wall and an inner sidewall extending substantially vertically from the bottom wall, wherein the inner sidewall of the receiving concavity is fitted with an outer surface of the protrusion so that the elastic valve cap is in a sealed connection with the protrusion, a flow-passing gap is formed between an outer sidewall of the elastic valve cap and a hole wall of the first flow-passing hole, a top end surface of the protrusion is in contact with the bottom wall of the receiving concavity, and the second flow-passing hole comprises a conical hole-section disposed on the top end surface, the conical hole-section diminishing gradually from the top end surface towards the inlet end; a valve cover in connection with the exhaust end, wherein the valve cover is disposed within the first flow-passing hole and is pressed against the elastic valve cap and comprises an exhaust passage in connection with the first flow-passing hole. a valve body comprising an inlet end and an exhaust end opposite to each other in an axial direction of the valve body and an airflow passage penetrating through the inlet end and the exhaust end, wherein the valve body is a columnar structure, the airflow passage comprises a first flow-passing hole and a second flow-passing hole distributed from the exhaust end to the inlet end, and the valve body further comprises a protrusion disposed on a bottom wall of the first flow-passing hole and extending towards the exhaust end, the second flow-passing hole penetrating through the protrusion; an elastic valve cap comprising a receiving concavity, the receiving concavity being a circular blind hole having a bottom wall and an inner sidewall extending substantially vertically from the bottom wall, wherein the inner sidewall of the receiving concavity is fitted with an outer surface of the protrusion so that the elastic valve cap is in a sealed connection with the protrusion, a flow-passing gap is formed between an outer sidewall of the elastic valve cap and a hole wall of the first flow-passing hole, a top end surface of the protrusion is in contact with the bottom wall of the receiving concavity, and the second flow-passing hole comprises a conical hole-section disposed on the top end surface, the conical hole-section diminishing gradually from the top end surface towards the inlet end; a valve cover in connection with the exhaust end, wherein the valve cover is disposed within the first flow-passing hole and is pressed against the elastic valve cap and comprises an exhaust passage in connection with the first flow-passing hole.