Top cover of power battery and power battery

1. A top cover of a power battery, comprising a top cover sheet, a first electrode unit and a second electrode unit, wherein,

the first electrode unit comprises a turning sheet, an insulating piece and a current cutting-off structure,

an assembling hole is provided on the top cover sheet, the current cutting-off structure is fixed in a radial projection range of the assembling hole, and is electrically connected with the top cover sheet,

the turning sheet is fixed at an underneath of the top cover sheet through the insulating piece, the turning sheet is electrically connected with the top cover sheet merely through the current cutting-off structure,

the second electrode unit is electrically insulated from the top cover sheet, and the turning sheet is capable of turning and breaking the current cutting-off structure when an internal pressure of the power battery exceeds a reference pressure, so as to cut off an electrical connection of the current cutting-off structure with the top cover sheet,

the insulating piece is sealed and fixed with the top cover sheet, and the turning sheet is sealed and fixed with the insulating piece, and

the first electrode unit further comprises a sealing ring, wherein the sealing ring is provided between the insulating piece and the top cover sheet, and seals a gap between the insulating piece and the top cover sheet.

2. The top cover of the power battery according to claim 1 , wherein, the turning sheet directly contacts with a bottom of the current cutting-off structure.

3. The top cover of the power battery according to claim 1 , wherein, the current cutting-off structure seals the assembling hole.

4. The top cover of the power battery according to claim 1 , wherein, the first electrode unit further comprises a connecting plate,

wherein the connecting plate covers the assembling hole and is electrically connected with the top cover sheet.

5. The top cover of the power battery according to claim 4 , wherein, a groove is provided at a bottom of the connecting plate, and the groove is opposite to the assembling hole.

6. The top cover of the power battery according to claim 5 , wherein, a projection of the assembling hole in a direction perpendicular to a thickness direction of the top cover sheet overlaps with or is located within a projection of the groove in a same direction.

7. The top cover of the power battery according to claim 1 , wherein, the turning sheet comprises a fixing portion, a connecting convex head and a turning portion,

wherein the turning portion is a sheet shaped structure with a ring surface, the fixing portion is fixed and connected with an edge of the turning portion, the connecting convex head is located in the middle of the turning portion, protrudes toward a lower surface of the current cutting-off structure and contacts with the current cutting-off structure.

8. The top cover of the power battery according to claim 1 , wherein, the current cutting-off structure and the top cover sheet are integrally formed.

9. The top cover of the power battery according to claim 1 , wherein, the insulating piece is adhered to the top cover sheet.

10. The top cover of the power battery according to claim 1 , wherein, further comprising a connecting piece, wherein the insulating piece is connected with the top cover sheet through the connecting piece.

11. The top cover of the power battery according to claim 10 , wherein, a connecting piece fitting portion is provided on the insulating piece and/or the top cover sheet, and the connecting piece is fitted and fixed with the connecting piece fitting portion.

12. The top cover of the power battery according to claim 1 , wherein, an inserting slot is provided on the insulating piece, and an edge of the turning sheet is inserted in the inserting slot and is sealed and connected with the inserting slot.

13. A power battery, comprising a cell and the top cover of the power battery according to claim 1 , wherein the cell is electrically connected with the turning sheet.