Non-aqueous electrolyte secondary cell

1. A non-aqueous electrolyte secondary battery comprising:

an outer can having an opening;

an electrode assembly housed in the outer can, the electrode assembly comprising a positive electrode having a positive electrode current collector and a negative electrode having a negative electrode current collector;

a sealing plate sealing the opening;

a current collecting tab connected to one of the positive electrode current collector and the negative electrode current collector;

an external electrode terminal projecting outside the sealing plate;

a diaphragm disposed inside the sealing plate and outside the current collecting tab in the battery, the diaphragm being electrically connected to the external electrode terminal and deforming toward an outside of the battery when a battery internal pressure increases;

a fragile portion connected at a center portion thereof to an inner surface of the diaphragm and also connected at a periphery thereof to the current collecting tab disposed below the diaphragm, the fragile portion breaking when the diaphragm deforms and rises upward, thereby interrupting current flow to the diaphragm;

a current collecting tab holder into which a part of the current collecting tab is inserted, wherein

the current collecting tab includes a planar insert member having the fragile portion and a current collector connecting portion connected to one of the positive electrode current collector and the negative electrode current collector;

the current collecting tab holder is insulating and has a tab receiving portion into which an insert member of the current collecting tab is inserted, the tab receiving portion is provided on both an inner surface and an outer surface thereof with a holder hole, the holder hole overlapping with the fragile portion when the insert member is inserted;

the diaphragm is disposed outside the tab receiving portion so as to cover the holder hole and is electrically connected at a center bottom thereof to the fragile portion via the holder hole;

the external electrode terminal is swaged and fitted to a hole provided in the sealing plate via a gasket and an insulating plate;

the current collecting tab holder is a different member from the gasket and the insulating plate; and

wherein the diaphragm, external electrode terminal and current collecting tab holder are aligned in a plane that is perpendicular to the sealing plate.

2. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the planar insert member of the current collecting tab has a throughhole; and

the fragile portion is formed of a metal thin film covering the throughhole.

3. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the current collecting tab is made of one of aluminum and aluminum alloy; and

the external electrode terminal is a positive electrode terminal.

4. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the sealing plate includes a flat surface and a projection projecting outside the flat surface, the projection allowing the external electrode terminal to project therefrom toward the outside of the battery and accommodating an inner end of the external electrode terminal in an inner space thereof.

5. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the electrode assembly is a coiled electrode assembly comprising a positive electrode and a negative electrode coiled together and is housed in the outer can parallelly to a bottom of the can; and

the current collector connecting portion of the current collecting tab is connected to one of positive-electrode current-collector protrusions and negative-electrode current-collector protrusions projecting from one end surface of the coiled electrode assembly.

6. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the external electrode terminal is provided therein with a pressure release hole consisting of a vertical hole and a horizontal hole, the vertical hole extending in a perpendicular direction to the sealing plate from an inner end to an outer end of the battery, and the horizontal hole having an opening open to the outside of the battery and parallel to the sealing plate and being communicated with the vertical hole.

7. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the sealing plate further includes a gas relief valve, and

the fragile portion has a smaller operating pressure than the gas relief valve.

8. The non-aqueous electrolyte secondary battery of claim 1 , wherein

the outer can is prismatic in shape.

9. The non-aqueous electrolyte secondary battery of claim 2 , wherein

the current collecting tab is made of one of aluminum and aluminum alloy; and

the external electrode terminal is a positive electrode terminal.

10. The non-aqueous electrolyte secondary battery of claim 9 , wherein

the sealing plate includes a flat surface and a projection projecting outside the flat surface, the projection allowing the external electrode terminal to project therefrom toward the outside of the battery and accommodating an inner end of the external electrode terminal in an inner space thereof.

11. The non-aqueous electrolyte secondary battery of claim 10 , wherein

the electrode assembly is a coiled electrode assembly comprising a positive electrode and a negative electrode coiled together and is housed in the outer can parallelly to a bottom of the can; and

the current collector connecting portion of the current collecting tab is connected to positive-electrode current-collector protrusions or negative-electrode current-collector protrusions projecting from one end surface of the coiled electrode assembly.

12. The non-aqueous electrolyte secondary battery of claim 11 , wherein

the external electrode terminal is provided therein with a pressure release hole consisting of a vertical hole and a horizontal hole, the vertical hole extending in a perpendicular direction to the sealing plate from an inner end to an outer end of the battery, and the horizontal hole having an opening open to the outside of the battery and parallel to the sealing plate and being communicated with the vertical hole.

13. The non-aqueous electrolyte secondary battery of claim 12 , wherein

the sealing plate further includes a gas relief valve, and

the fragile portion has a smaller operating pressure than the gas relief valve.

14. The non-aqueous electrolyte secondary battery of claim 13 , wherein

the outer can is prismatic in shape.

15. The non-aqueous electrolyte secondary battery of claim 5 , wherein

the current collector connecting portion of the current collecting tab is designed to sandwich the one of the positive-electrode current-collector protrusions and the negative-electrode current-collector protrusions projecting from the one end surface of the coiled electrode assembly.

16. The non-aqueous electrolyte secondary battery of claim 15 , wherein

the current collecting tab holder is made of an insulating resin.

17. The non-aqueous electrolyte secondary battery of claim 16 , wherein

the planar insert member of the current collecting tab has a throughhole; and

the fragile portion is formed of a metal thin film covering the throughhole.

18. The non-aqueous electrolyte secondary battery of claim 17 , wherein

the sealing plate includes a flat surface and a projection projecting outside the flat surface, the projection allowing the external electrode terminal to project therefrom toward the outside of the battery and accommodating an inner end of the external electrode terminal in an inner space thereof.

19. The non-aqueous electrolyte secondary battery of claim 18 , wherein

the external electrode terminal is provided therein with a pressure release hole consisting of a vertical hole and a horizontal hole, the vertical hole extending in a perpendicular direction to the sealing plate from an inner end to an outer end of the battery, and the horizontal hole having an opening open to the outside of the battery and parallel to the sealing plate and being communicated with the vertical hole.

20. The non-aqueous electrolyte secondary battery of claim 19 , wherein

the sealing plate further includes a gas relief valve, and

the fragile portion has a smaller operating pressure than the gas relief valve.