LITHIUM SECONDARY BATTERY

• US 20020015892A1
• Filed: 06/01/1999
• Published: 02/07/2002
• Est. Priority Date: 06/02/1998
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: KITOH, KENSHIN
• Granted Patent: US 6,753,104 B2
• Time in Patent Office: Days
• US Class Current: 429/243
• CPC Class Codes: B60K 6/28 characterised by the electric energy storing means, e.g. batteries or capacitors
• CPC Class Codes: H01M 10/0431 Cells with wound or folded electrodes H01M10/045 takes precedence
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 50/534 characterised by the material of the leads or tabs
• CPC Class Codes: H01M 50/536 characterised by the method of fixing the leads to the electrodes, e.g. by welding
• CPC Class Codes: H01M 50/538 Connection of several leads or tabs of wound or folded electrode stacks
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 903/907 Electricity storage, e.g. battery, capacitor

Abstract

A lithium secondary battery includes an internal electrode body including a positive electrode, a negative electrode, and a separator. The positive electrode and the negative electrode are wound or laminated via the separator so that the positive electrode and the negative electrode are not brought into direct contact with each other. At least a plurality of tabs for current collecting were provided to have a total cross-sectional area of the tabs be not less than a constant area in accordance with the quality of the material to be used for the tabs so that the tabs to be connected to each of the positive and negative electrodes may not respectively fuse when at least 100 A current has flown through the lithium secondary battery. The lithium secondary battery maintains a good charge-discharge cycle characteristics, and safety may be secured with electricity being cut off when an excess current has occurred due to external short circuit, etc., so that the battery may not be exploded nor be ignited. In particular, the lithium secondary battery may be preferably used for driving a motor of an electric vehicle, etc.

Claims

1. A lithium secondary battery, comprising:

an internal electrode body including a positive electrode, a negative electrode, and a separator, the positive electrode and the negative electrode being wound or laminated via the separator so that the positive electrode and the negative electrode are not brought into direct contact with each other;

an organic electrolyte; and

at least a plurality of tabs to be connected to each of the positive and negative electrodes for current collecting, the tabs having a total cross-sectional area of the tabs be not less than a constant area in accordance with the quality of the material to be used for the tabs so that the tabs to be connected to each of the positive and negative electrodes may not fuse when at least 100 A current flows through the lithium secondary battery.

2. The lithium secondary battery according to claim 1, wherein the relationship between material of tabs and total cross-sectional area of the tabs is not less than 0.009 cm² for aluminum, not less than 0.005 cm² for copper, and not less than 0.004 cm² for nickel, and preferably not less than 0.014 cm² for aluminum, not less than 0.008 cm² for copper, and not less than 0.008 cm² for nickel.

3. The lithium secondary battery according to claim 1, wherein a thickness of a tab is not more than twice a thickness of an electrode active material layer in an electrode to which the tabs are welded, and preferably not more than a thickness of the electrode active material layer.

4. The lithium secondary battery according to claim 2, wherein a thickness of a tab is not more than twice a thickness of an electrode active material layer in an electrode to which the tabs are welded, and preferably not more than a thickness of the electrode active material layer.

5. The lithium secondary battery according to claim 1, wherein a sum of resistance value of the tabs per a unit battery is not more than 1 mΩ

.

6. The lithium secondary battery according to claim 2, wherein a sum of resistance value of the tabs per a unit battery is not more than 1 mΩ

.

10. The lithium secondary battery according to claim 1, wherein internal resistance is not more than 10 mΩ

per a unit battery.

12. The lithium secondary battery according to claim 1, wherein when internal resistance of a unit battery is set R (mΩ

), the relationship between material of the tabs and total cross-sectional area of the tabs is not less than 0.008 cm² and not more than 0.36/R cm² for aluminum, not less than 0.005 cm² and not more than 0.18/R cm² for copper, and not less than 0.004 cm² and not more than 0.14/R cm² for nickel, and preferably not less than 0.014 cm² and not more than 0.18/R cm² for aluminum, not less than 0.008 cm² and not more than 0.09/R cm² for copper, and not less than 0.008 cm² and not more than 0.07/R cm² for nickel.

14. The lithium secondary battery according to claim 1, wherein deviation of respective resistance values of the tabs remains within ±

20% of an average value.

16. The lithium secondary battery according to claim 1, wherein an end part of the tab at the side with no connection taking place with the electrodes is connected by pressure attachment, welding or eyelet.

18. The lithium secondary battery according to claim 1, wherein battery capacity is not less than 5 Ah.

20. The lithium secondary battery according to claim 1, wherein the battery is used for an electric vehicle or a hybrid electric vehicle.

7. A lithium secondary battery, comprising:

an internal electrode body including a positive electrode, a negative electrode, and a separator, the positive electrode and the negative electrode being wound or laminated via a separator so that the positive electrode and the negative electrode are not brought into direct contact with each other;

an organic electrolyte; and

at least a plurality of tabs to be connected to each of the positive and negative electrodes for current collecting,

wherein the tabs function as current fuses.

8. The lithium secondary battery according to claim 7, wherein the relationship between material of the tabs and total cross-sectional area of the tabs when internal resistance of a unit battery is set R (mΩ

) is not more than 0.36/R (cm²) for aluminum, not more than 0.18/R (cm²) for copper, and not more than 0. 14/R (cm) for nickel, and preferably not more than 0. 18/R (cm²) for aluminum, not more than 0.09/R (cm²) for copper, and not more than 0.07/R (cm²) for nickel.

9. The lithium secondary battery according to claim 8, wherein the tabs are provided with a narrow portion.

11. The lithium secondary battery according to claim 7, wherein internal resistance is not more than 10 mΩ

per a unit battery.

13. The lithium secondary battery according to claim 7, wherein when internal resistance of a unit battery is set R (mΩ

), the relationship between material of the tabs and total cross-sectional area of the tabs is not less than 0.008 cm² and not more than 0.36/R cm² for aluminum, not less than 0.005 cm² and not more than 0.18/R cm² for copper, and not less than 0.004 cm² and not more than 0.14/R cm² for nickel, and preferably not less than 0.014 cm² and not more than 0.18/R cm² for aluminum, not less than 0.008 cm²and not more than 0.09/R cm² for copper, and not less than 0.008 cm² and not more than 0.07/R cm² for nickel.

15. The lithium secondary battery according to claim 7, wherein deviation of respective resistance values of the tabs remains within ±

20% of an average value.

17. The lithium secondary battery according to claim 7, wherein an end part of the tab at the side with no connection taking place with the electrodes is connected by pressure attachment, welding or eyelet.

19. The lithium secondary battery according to claim 7, wherein battery capacity is not less than 5 Ah.

21. The lithium secondary battery according to claim 7, wherein the battery is used for an electric vehicle or a hybrid electric vehicle.