US-12621554-B2 - Welding inspection apparatus for inspecting a battery can

Abstract

A welding inspection apparatus and a welding inspection method in which in a tab-less cylindrical battery cell having a jelly roll-type electrode assembly, a current collection plate welded to an uncoated part of the electrode assembly is welded to an electrode terminal that is fixed in a way that penetrates a closed surface provided in one end portion of a cylindrical battery can which accommodates the electrode assembly, from the inside of a hollow hole part of the electrode assembly, to see a welding state. The battery can is fixed by a jig, and the welding inspection apparatus, as a vision camera inspection apparatus with an endoscope part or a telephoto lens, photographs a welding portion and the inner surface of the hollow hole part, to see failure caused by weak welding, over welding or weld spatter.

Inventors

• Kyuhun SHIM
• Gilyoung LEE
• Junoh LEE

Assignees

• LG ENERGY SOLUTION, LTD.

Dates

Publication Date

20260505

Application Date

20221108

Priority Date

20211108

Claims (17)

1. 1 . A welding inspection apparatus for inspecting a welding portion between a first electrode terminal being fixed to a closed surface of a battery can, and a first current collection plate of an electrode assembly being accommodated in a battery can, the welding inspection apparatus comprising: a jig configured to support the battery can such that an open part of the battery can faces in a first direction; and a camera being disposed to face the open part, the camera comprising: an image sensor configured to obtain an image; and a lens being disposed between the image sensor and the welding portion such that a focal point of the image concentrates on the image sensor, wherein the jig supports the electrode assembly such that a central axis of the electrode assembly is parallel with the first direction, wherein the image sensor and the lens are aligned with a hollow hole part of the electrode assembly, the hollow hole part being elongated along the central axis of the electrode axis in the first direction, and wherein the camera is configured to extend into the battery can.
2. 2 . The welding inspection apparatus of claim 1 , wherein the camera further comprises an endoscope part having an outer diameter that is less than an inner diameter of the hollow hole part such that the endoscope part is configured to be inserted into the hollow hole part along the first direction to approach the welding portion, and wherein the endoscope part includes: the lens at an end portion thereof in the first direction; and a lighting device at the end portion.
3. 3 . The welding inspection apparatus of claim 2 , wherein the lighting device is integrated with the lens.
4. 4 . The welding inspection apparatus of claim 2 , wherein the endoscope part is provided with a sub motor to move freely along an X-axis, a Y-axis and a Z-axis.
5. 5 . The welding inspection apparatus of claim 1 , wherein the lens has a long focal length to photograph the welding portion such that the lens is not inserted into the hollow hole part.
6. 6 . The welding inspection apparatus of claim 2 , wherein the lens has a wide angle of view to see weld spatter on an inner circumferential surface of the hollow hole part.
7. 7 . A welding inspection method for inspecting a welding portion between a first electrode terminal being fixed to a closed surface of a battery can, and a first current collection plate of an electrode assembly being accommodated in a battery can, the welding inspection method comprising: using the welding inspection apparatus of claim 1 to obtain an image of the welding portion, and analyzing the image of the welding portion to determine whether the welding portion is defective.
8. 8 . The welding inspection method of claim 7 , wherein the battery can is supported on a linear track.
9. 9 . The welding inspection method of claim 8 , wherein the welding inspection method is performed within 300 ms or less.
10. 10 . The welding inspection method of claim 8 , wherein the welding inspection method is performed within 200 ms or less.
11. 11 . A welding inspection method for inspecting a welding portion between a first electrode terminal being fixed to a closed surface of a battery can, and a first current collection plate of an electrode assembly being accommodated in a battery can, the welding inspection method comprising: using the welding inspection apparatus of claim 6 to obtain an image of the inner circumferential surface of the hollow hole part; and analyzing the image of the inner circumferential surface of the hollow hole part to see failure caused by weld spatter.
12. 12 . The welding inspection method of claim 11 , wherein the battery can is supported on a linear track.
13. 13 . The welding inspection method of claim 12 , wherein the welding inspection method is performed within 300 ms or less.
14. 14 . The welding inspection method of claim 12 , wherein the welding inspection method is performed within 200 ms or less.
15. 15 . The welding inspection apparatus of claim 3 , wherein the lens has a wide angle of view to see weld spatter on an inner circumferential surface of the hollow hole part.
16. 16 . The welding inspection apparatus of claim 4 , wherein the lens has a wide angle of view to see weld spatter on an inner circumferential surface of the hollow hole part.
17. 17 . The welding inspection apparatus of claim 1 , wherein the jig comprises a recess in a first surface for supporting the battery can, and wherein an end of the camera extends below the first surface.

Description

TECHNICAL FIELD This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0152638 filed on Nov. 8, 2021, and Korean Patent Application No. 10-2022-0055065 filed on May 3, 2022, the disclosure of which is incorporated herein by reference in its entirety. The present disclosure relates to a welding inspection apparatus, and in particular, an apparatus used to see a welding state in a hollow hole part of a cylindrical electrode assembly on a linear track. BACKGROUND ART Secondary batteries are highly applicable to various product groups, and exhibit electrical properties such as high energy density and the like. Accordingly, secondary batteries are universally applied to electric vehicles (EV) or hybrid vehicles (HEV) and the like driven by an electric driving source as well as mobile devices. Secondary batteries not only help to reduce the consumption of fossil fuels significantly but also produce no by-products after the use of their energy. Thus, secondary batteries are hailed as an alternative energy source that protect the environment and improve energy efficiency. Secondary batteries include a lithium-ion battery, a lithium-polymer battery, a nickel-cadmium battery, a nickel-hydrogen battery, a nickel-zinc battery and the like that are currently used. The operating voltage of such a unit secondary battery cell, i.e., a unit battery cell, is about 2.5 V to 4.5 V. When an output voltage higher than the operating voltage is required, a plurality of battery cells connects in series, to constitute a battery pack. Additionally, a plurality of battery cells connects in parallel to constitute a battery pack, depending on the charge capacity or discharge capacity required of the battery pack. The number of battery cells included in the battery packs, and the electric connection form of the battery cells can vary depending on a required output voltage and/or charge and discharge capacity. Additionally, unit secondary battery cells include a cylindrical battery cell, a prismatic battery cell, and a pouch-type battery cell. In the case of a cylindrical battery cell, a separation layer as an insulator is interposed between an anode and a cathode, and the stack of electrodes and separation layer is wound to form a jelly roll-type electrode assembly, and the jelly roll-type electrode assembly is inserted into a battery can, to form a battery. Further, a strip-shaped electrode tab can connect to an uncoated part of each of the anode and the cathode, and electrically connects between the electrode assembly and an electrode terminal that is exposed outward. A positive electrode terminal is a cap plate of a sealing body that seals an opening of a battery can, and a negative electrode terminal is a battery can. In a cylindrical battery cell having the above-described structure, current concentrates on the strip-shaped electrode tab coupled to an anode uncoated part and/or a cathode uncoated part, causing high resistance and a large amount of heat, and deterioration in the efficiency of collecting current. The resistance and heat generation of a small-sized cylindrical battery call having a form factor of a 18650 or 21700 battery are not a bug issue. However, in the case where the form factor increases to apply the cylindrical battery cell to an electric vehicle, a large amount of heat is generated around the electrode tab during rapid charge, and the cylindrical battery cell causes a fire. To solve the problem, an anode uncoated part and a cathode uncoated part are respectively disposed at the upper end and the lower end of the jelly roll-type electrode assembly, and a current collection plate is welded to the uncoated parts, to manufacture a cylindrical battery cell (the so-called tab-less cylindrical battery cell) ensuring improvement in the efficiency of collecting current. Among tab-less cylindrical battery cells, there may be a battery cell, in which the electrode assembly electrically connects to the outside, in a way that a current collection plate is welded to an uncoated part of an electrode assembly, and also welded from the inside of the battery can to an electrode terminal, which is fixed to penetrate one end portion of a battery can and protrudes out of the battery can. FIG. 1 is a lateral cross-sectional view showing an uncoated part of an electrode assembly and a first current collection plate are welded, and then a first electrode terminal rivet-fixed to one end portion of a battery can and the first current collection plate are welded while a cylindrical battery cell is manufactured. Referring to FIG. 1, the first current collection plate 13 is welded to a first uncoated part 111a, and the electrode assembly 11 is accommodated in the battery can 12 in a way that a second uncoated part 111b faces an open part 121 of the battery can 12. The first current collection plate 13 is welded to a first electrode terminal 15 in a welding portion 13W at one end portion of the hollow h