CIRCULAR LITHIUM BATTERY AND METHOD FOR PRODUCING THE SAME

Abstract

A cylindrical lithium battery and a producing method thereof are disclosed. The lithium battery includes a shell, a battery cell, a cathode battery cover-plate assembly and an anode battery cover-plate assembly. A cathode foil and an anode foil are separated by a separator and wind into a cylindrical battery cell. The cathode is of a multi-tab structure and the anode is of a full-tab structure. A sealing body is fixed on the cathode battery cover plate in a surrounding manner, and a safety valve is provided at the middle of the cathode battery cover plate. The anode battery cover-plate assembly includes a current collector, an anode battery cover plate and a current collector support. The current collector body is fixedly connected to the upper portion of the current collector support and is electrically connected to the anode battery cover plate via a current collector connecting portion.

Claims

1. A cylindrical lithium battery comprising a shell, a battery cell, a cathode battery cover-plate assembly and an anode battery cover-plate assembly, the shell being a metal pipe, the battery cell being positioned inside the shell, and the battery cell comprising a cathode foil, an anode foil and a separator, the cathode foil and the anode foil being separated by the separator and winding into a cylinder, wherein a plurality of cathode tabs are provided at interval on an upper end of the cathode foil; a lower end of the battery cell is arranged in an unaligned manner, wherein at the lower end of the battery cell, the cathode foil, the separator and the anode foil are arranged in ascending order in length, and an extension portion of the anode foil is covered by the lower end of the battery cell by pressing, and is separated from the cathode foil by the separator; the cathode battery cover-plate assembly comprises a disc-shaped cathode battery cover plate and a sealing body, and the sealing body is configured to an annular structure, the sealing body is arranged along the periphery of the cathode battery cover plate and is fixedly connected to the cathode battery cover plate, the cathode battery cover plate is provided with a safety valve, and the cathode tabs are electrically connected to the cathode battery cover plate; and the anode battery cover-plate assembly comprises a current collector, an anode battery cover plate, and a current collector support, the current collector support is an annular part having a notch at a side thereof, the current collector has a current collector body and a current collector connecting portion, the current collector body is fixedly connected to an upper portion of the current collector support, the current collector connecting portion is located at the side of the annular part with the notch, and the current collector connecting portion is fixedly connected to the cover plate, the current collector connecting portion has a flexible bent structure, enabling the cover plate to be positioned below the current collector support in an installation state, the current collector body is electrically connected to the extension portion of the anode foil.

2. The cylindrical lithium battery of claim 1, wherein a through hole is provided at the center of the cathode battery cover plate, a periphery of the through hole has a stepped structure, the through hole is used as a liquid injection hole, the through hole and the stepped structure at the periphery of the through hole together constitute an installation position for the safety valve, while the battery is in a factory state, the safety valve is fixed at the installation position for the safety valve, the cathode battery cover plate is provided with a periphery, a thickness of the periphery is less than a thickness of the cathode battery cover plate, to form a sealing body fixation portion, the sealing body encloses the sealing body fixation portion, and one end of the shell covers the sealing body through mechanical rolling, so that the shell is hermetically fixed to the cathode battery cover plate.

3. The cylindrical lithium battery of claim 2, wherein the safety valve comprises a safety valve body and a safety valve cap, the stepped structure at the periphery of the through hole has a first step and a second step shallower than the first step, wherein the through hole, the first step and the second step are arranged sequentially from inside to outside, and the periphery of the safety valve body is fixed to the first step and the safety valve cap is fixed to the second step.

4. The cylindrical lithium battery of claim 1, wherein the current collector body is substantially disc-shaped, the current collector body has a bending portion that is bent downward at the periphery of the current collector body, the annular part is a plastic part, and the annular part encloses the bending portion of the current collector body by injection molding, so that the current collector body and the annular part form an integral structure.

5. The cylindrical lithium battery of claim 4, wherein the current collector body has several reinforcement grooves that are radially arranged thereon, and the current collector body has a sector portion between adjacent reinforcement grooves, the sector portion constitutes an anode welding and connecting portion.

6. The cylindrical lithium battery of claim 5, wherein four reinforcement grooves are arranged evenly at an interval of angle 90° on the current collector body, the notch is provided between two of the reinforcement grooves, and the notch has a radian between 60° and 90° on the circumference of the annular part.

7. The cylindrical lithium battery of claim 1, wherein an extension length of the anode foil beyond the battery cell after being pressed make adjacent layers of anode foil overlap each other, forming an anode lead-out portion.

8. The cylindrical lithium battery of claim 1, wherein the shell is a stainless steel pipe or stainless iron pipe.

9. A method for producing a cylindrical lithium battery of claim 1, comprising steps of: (1) stacking the cathode foil and the anode foil and separating the cathode foil and the anode foil with the separator, then winding them into a cylinder; (2) shaping and ultrasonically welding the cathode tabs, and flattening the extension portion of the anode foil, to form a battery cell; (3) laser welding the anode battery cover plate with the current collector connecting portion to obtain the anode battery cover-plate assembly; (4) multiple spot welding the extension portion of the anode foil with the current collector body, making the anode battery cover-plate assembly assemble to the battery cell, obtaining an anode battery cover plate-battery cell assembly; (5) placing the anode battery cover plate-battery cell assembly into the shell, and completely sealing the periphery of the anode battery cover plate and the shell by welding; (6) welding the cathode tabs to a back side of the cathode battery cover plate, then installing the cathode battery cover plate in the shell, and fixing and sealing the shell to the cathode battery cover plate through mechanical rolling; (7) extracting air from the battery through the through hole on the cathode battery cover plate and injecting electrolyte; and (8) fixing the safety valve onto the through hole by welding, to accomplish assembly of the lithium battery.

10. The method for producing a cylindrical lithium battery of claim 9, wherein the safety valve cap is installed after welding and fixing of the safety valve, and then the whole battery is enveloped with an outer insulation film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] FIG. 1 is a schematic structural sectional view of an embodiment of the present invention;

[0039] FIG. 2 is a top view of FIG. 1;

[0040] FIG. 3 is a schematic exploded view of FIG. 1;

[0041] FIG. 4 is a schematic structural view of the battery cell;

[0042] FIG. 5 is a schematic enlarged view of part B in FIG. 4;

[0043] FIG. 6 is a top view of the cathode cover-plate assembly in an embodiment;

[0044] FIG. 7 is a sectional view along line A-A of FIG. 6;

[0045] FIG. 8 is a schematic exploded view of FIG. 7;

[0046] FIG. 9 is a schematic unfolded view of the anode battery cover-plate assembly of an embodiment;

[0047] FIG. 10 is a sectional view along the line C-C of FIG. 9; and

[0048] FIG. 11 is a schematic enlarged view of part D in FIG. 10.

REFERENCE NUMBERS IN THE DRAWINGS

[0049] 1 safety valve cap; 2 safety valve body; 3 cathode battery cover plate; 4 sealing body; 5 insulating spacer; 6 cathode tab; 7 shell; 8 battery cell; 9 current collector; 10 anode battery cover plate; 11 cathode foil; 12 anode foil; 13 separator; 14 through hole; 15 first step; 16 second step; 17 sealing body fixation portion; 18 current collector support; 19 notch; 20 current collector body; 21 current collector connecting portion; 22 bent portion; 23 reinforcement groove; 24 anode welding and connecting portion

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0050] The present invention will be further described with reference to the accompanying drawings and embodiments:

Embodiment 1

[0051] Referring to FIG. 1 to FIG. 3, a cylindrical lithium battery includes a shell 7, a battery cell 8, a cathode battery cover-plate assembly and an anode battery cover-plate assembly. The shell 7 is a stainless steel pipe. The battery cell 8 is positioned inside the shell 7.

[0052] Referring to FIG. 4 and FIG. 5, the battery cell 8 includes a cathode foil 11, an anode foil 12 and a separator 13. The cathode foil 11 and the anode foil 12 are separated by the separator 13 and then wound into a cylinder. A plurality of cathode tabs 6 are provided at interval on the upper end of the cathode foil 11. An insulating spacer 5 is provided between the battery cell 8 and the cathode battery cover-plate assembly. The lower end of the battery cell is provided in an unaligned manner, and at the lower end of the battery cell, the cathode foil 11, the separator 13 and the anode foil 12 are arranged in ascending order in length. An extension portion of the anode foil 12 is covered by the lower end of the battery cell by pressing and flattening, and is separated from the cathode foil 11 by the separator 13.

[0053] Referring to FIG. 6 to FIG. 8, the cathode battery cover-plate assembly includes a disc-shaped cathode battery cover plate 3 and a sealing body 4. The sealing body 4 is configured to an annular structure. The sealing body 4 is arranged along the periphery of the cathode battery cover plate 3 and is fixedly connected to the cathode battery cover plate 3. The cathode battery cover plate 3 is provided with a safety valve thereon. The cathode tabs 6 are electrically connected to the cathode battery cover plate 3.

[0054] A through hole 14 is provided at the center of the cathode battery cover plate 3. The periphery of the through hole 14 has a stepped structure which has a first step 15 and a second step 16 shallower than the first step 15. The safety valve body 2 is installed on the first step 15 and the safety valve cap 1 is installed on the second step 16.

[0055] The sealing body 4 is configured as an annular structure. To accommodate installation of the sealing body 4, the thickness of the periphery of the cathode battery cover plate 3 is smaller than the overall thickness of the cover plate so that a sealing body fixation portion 17 is formed. The sealing body 4 encloses the sealing body fixation portion 17 through pouring to increase the contact area, so that the integration of the sealing body with the battery cover plate is ensured. The sealing body fixation portion 17 is provided with a step thereon.

[0056] Referring to FIG. 9 to FIG. 11, The anode cover-plate assembly includes a current collector 9, a current collector support 18 and an anode battery cover plate 10. The current collector support 18 is an annular part having a notch 19 at one side thereof.

[0057] The current collector 9 may be a metal sheet made by stamping, and the current collector 9 has two functional parts: a current collector body 20 and a current collector connecting portion 21. The current collector body 20 is substantially disc-shaped. Referring to FIG. 10 and FIG. 11, the current collector body has a bent portion 22 that is bent ownward at the periphery of the current collector body. The annular current collector support 18 is injected molded to envelope the bending portion 22 so that the current collector body and the annular part form an integral structure. The current collector body 20 is positioned on the upper portion of the current collector support 18.

[0058] The current collector body 20 has four reinforcement grooves 23 that are radially arranged thereon. The reinforcement grooves 23 are arranged evenly at an interval of angle 90° on the current collector body. The current collector body has a sector portion between adjacent reinforcement grooves 23, and the sector portion forms an anode welding and connecting portion 24. The notch 19 is positioned between two of the reinforcement grooves. A circular through hole is provided at the center of the current collector body.

[0059] The current collector connecting portion 21 is positioned at the side of annular part with the notch, and the outer end of the current collector connecting portion is fixed to the anode battery cover plate 10 by welding. The current collector connecting portion 21 has a flexible bent structure, enabling the anode battery cover plate 10 to be positioned below the current collector support in an installed state.

[0060] The current collector body is fixedly connected to the upper portion of the current collector support. As such, the current collector support will not occlude the current collector body or the battery cell, so that a large area for welding exists between the current collector body and the extension portion of the anode of the battery cell, thereby ensuring uniformity in the current and the overcurrent capability of the electrode. Meanwhile, the current collector support also provides a positioning reference for the installation of the cover plate, which facilitates installation of the anode cover plate assembly.

[0061] The method for producing the cylindrical lithium battery in this embodiment includes the following steps: [0062] (1) stacking the cathode foil and the anode foil and separating the cathode foil and the anode foil with the separator, then winding them into a cylinder; [0063] (2) shaping and ultrasonically welding the cathode tabs, and flattening the extension portion of the anode foil, to form a battery cell; [0064] (3) laser welding the anode battery cover plate with the current collector connecting portion to obtain the anode battery cover-plate assembly; [0065] (4) multiple spot welding the extension portion of the anode foil with the current collector body, making the anode battery cover-plate assembly assemble to the battery cell, obtaining an anode battery cover plate-battery cell assembly; [0066] (5) placing the anode battery cover plate-battery cell assembly into the shell, and completely sealing the periphery of the anode battery cover plate and the shell by welding; [0067] (6) welding the cathode tabs to a back side of the cathode battery cover plate, then installing the cathode battery cover plate in the shell, and fixing and sealing the shell to the cathode battery cover plate through mechanical rolling; [0068] (7) extracting air from the battery through the through hole on the cathode battery cover plate and injecting electrolyte; and [0069] (8) fixing the safety valve onto the through hole by welding; [0070] (9) installing the safety valve cap; and [0071] (10) enveloping the whole battery with an outer insulating film, to accomplish assembly of the battery.