End cover assembly, secondary battery, battery module, apparatus, liquid-injection method and device

1. An end cover assembly for a secondary battery, comprising an end cover, provided with a through hole for injecting electrolyte therethrough and comprising a connecting portion; a sealing assembly, configured to seal the through hole; a locking-fixing member, configured to be movable relative to the connecting portion in a radial direction of the through hole, so as to realize switching between a locked state and an unlocked state of the locking-fixing member and the connecting portion, wherein in the locked state, the locking-fixing member presses against the sealing assembly to restrict the end cover from being separated from the sealing assembly; in the unlocked state, the end cover and the sealing assembly are separable to allow the electrolyte to be injected from the through hole, wherein the connecting portion is provided with a snapping slot, and at least part of the locking-fixing member is located in the snapping slot to restrict the locking-fixing member from moving in an axial direction of the through hole.

2. The end cover assembly according to claim 1 , wherein the locking-fixing member comprises an opening and an accommodating space communicating with each other, and the connecting portion is configured to enter the accommodating space through the opening, or the connecting portion is configured to be separated from the accommodating space through the opening.

3. The end cover assembly according to claim 1 , wherein the locking-fixing member is snap-fitted with the connecting portion, so that the locking-fixing member and the connecting portion are in the locked state.

4. The end cover assembly according to claim 1 , wherein the snapping slot comprises a position-limiting wall configured to resist against the locking-fixing member in the axial direction.

5. The end cover assembly according to claim 3 , wherein the sealing assembly comprises a position-limiting member and a sealing member, the sealing member seals the through hole, and the sealing member is arranged between the position-limiting member and the end cover.

6. The end cover assembly according to claim 5 , wherein the position-limiting member comprises a pressing-against portion and a position-limiting portion, the pressing-against portion is connected to the position-limiting portion and covers at least a part of the sealing member, and the locking-fixing member presses against the position-limiting portion to restrict the end cover from being separated from the sealing assembly.

7. The end cover assembly according to claim 6 , wherein the end cover further comprises a body portion, and the connecting portion is a boss protruding from a surface of the body portion.

8. The end cover assembly according to claim 7 , wherein the through hole is located outside the connecting portion and penetrates the body portion in its own axial direction; each of the position-limiting member and the sealing member has an annular structure and is sleeved and connected to the connecting portion.

9. The end cover assembly according to claim 7 , wherein the through hole penetrates the connecting portion and the body portion in its own axial direction, and at least part of the sealing member is located at a side of the connecting portion in the axial direction.

10. The end cover assembly according to claim 9 , wherein the position-limiting member further comprises an accommodating slot and a supporting portion connecting to the pressing-against portion and the position-limiting portion, and the accommodating slot penetrates the supporting portion in the radial direction;

the connecting portion passes through the accommodating slot, and a portion of the connecting portion located outside the accommodating slot is misaligned with the position-limiting portion in a peripheral direction of the through hole, and is configured to be locked with the locking-fixing member.

11. The end cover assembly according to claim 5 , wherein the end cover comprises a concave slot, the through hole is communicated with the concave slot, and at least part of the sealing member is accommodated in the concave slot.

12. A secondary battery, comprising the end cover assembly according to claim 1 .

13. A battery module, comprising the secondary battery according to claim 12 .

14. An apparatus comprising the secondary battery according to claim 12 , the secondary battery being configured to supply electrical power.

15. A liquid-injection method for a secondary battery, comprising providing an end cover that comprises a through hole and a connecting portion, injecting electrolyte through the through hole; providing a sealing assembly; mounting the sealing assembly to the end cover; providing a locking-fixing member, and moving the locking-fixing member toward a direction close to the connecting portion in a radial direction of the through hole, so that the locking-fixing member locks the connecting portion to restrict the end cover from being separated from the sealing assembly, wherein the connecting portion is provided with a snapping slot, and at least part of the locking-fixing member is located in the snapping slot to restrict the locking-fixing member from moving in an axial direction of the through hole.

16. The liquid-injection method according to claim 15 , further comprising

moving the locking-fixing member toward a direction away from the connecting portion in the radial direction of the through hole, so as to unlock the locking-fixing member and the connecting portion, and separate the locking-fixing member from the end cover.

17. The liquid-injection method according to claim 16 , after the moving the locking-fixing member in the direction away from the connecting portion in the radial direction of the through hole, the method further comprising

removing the sealing assembly from the end cover.

18. A liquid-injection device, for injecting the electrolyte into the secondary battery according to claim 13 , comprising

a liquid injection component, configured to inject the electrolyte into the through hole; and

a dismounting-and-mounting component of the locking-fixing member, configured to move the locking-fixing member toward a direction close to the connecting portion in the radial direction of the through hole in the unlocked state, so that the locking-fixing member locks the connecting portion to restrict the end cover from being separated from the sealing assembly; or configured to move the locking-fixing member toward a direction away from the connecting portion in the radial direction of the through hole, so that the locking-fixing member and the connecting portion are unlocked.

19. The liquid-injection device according to claim 18 , further comprising

a dismounting-and-mounting component of the sealing assembly, configured to mount the sealing assembly on the end cover, or dismount the sealing assembly from the end cover.