Top cover assembly, secondary battery and apparatus using battery

1. A top cover assembly of a secondary battery, the top cover assembly comprising:

a top cover sheet provided with an explosion-proof hole;

an explosion-proof sheet, a position of the explosion-proof sheet corresponding to the explosion-proof hole; and

a fixing member, at least part of the fixing member being located between the top cover sheet and the explosion-proof sheet and connecting the top cover sheet and the explosion-proof sheet,

wherein one of the explosion-proof hole and the fixing member is provided with a protrusion and the other is provided with a first groove,

the protrusion and the first groove are fixed,

the protrusion is arranged on one side of an inner wall of the explosion-proof hole facing towards a central axis of the explosion-proof hole, the first groove is arranged on one side of the fixing member facing towards the top cover sheet, a second groove is arranged on one side of the fixing member facing towards the explosion-proof sheet, the explosion-proof sheet comprises a main body and a stretching-into portion located on an end part of the main body, and the stretching-into portion stretches into the second groove to be fixed;

the protrusion is located at a center of the inner wall of the explosion-proof hole along a height direction of the top cover assembly; and

a center line of the protrusion coincides with a center line of the stretching-into portion along a length direction of the top cover assembly.

2. The top cover assembly according to claim 1 , wherein a thickness of the stretching-in portion is greater than a thickness of the main body along a height direction of the top cover assembly.

3. The top cover assembly according to claim 1 , wherein the main body is provided with a nick; and

a projection of the nick along a height direction of the top cover assembly is located inside an inner side of a projection of the fixing member along the height direction of the top cover assembly.

4. The top cover assembly according to claim 1 , wherein the explosion-proof sheet is located above the protrusion along a height direction of the top cover assembly.

5. The top cover assembly according to claim 1 , wherein a melting point of the explosion-proof sheet and/or the fixing member is 80° C.-300° C.

6. The top cover assembly according to claim 5 ,

wherein the explosion-proof sheet and the fixing member are integrally molded.

7. The top cover assembly according to claim 1 , wherein the explosion-proof sheet is a metal member, and the fixing member is a plastic member.

8. The top cover assembly according to claim 7 , wherein the explosion-proof sheet and the fixing member are of split structures.

9. The top cover assembly according to claim 1 , wherein a sealing layer is arranged between the fixing member and the explosion-proof sheet and/or between the fixing member and the top cover sheet.

10. The top cover assembly according to claim 1 , wherein the top cover assembly further comprises a protective sheet, and the protective sheet is configured to cover a connecting interface between the fixing member and the top cover sheet.

11. A secondary battery, comprising:

a housing provided with an opening;

an electrode assembly accommodated in the housing; and

the top cover assembly of claim 1 , wherein the top cover assembly covers the opening to close the electrode assembly in the housing.

12. An apparatus using a battery, the apparatus comprising the secondary battery of claim 11 .