# US 11,897,054 B2 · Laser welding method and monitoring method for secondary battery

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- Number: US 11,897,054 B2
- Document ID: US11897054B2
- Status: Granted
- Kind: B2
- Application number: 17/172,683
- Filed: 2021-02-10
- Published: 2021-08-19
- Granted: 2024-02-13
- Earliest claimed: 2020-02-17
- Assignees: Samsung SDI Co., Ltd.
- Applicants: Samsung SDI Co., Ltd.
- Inventors: Jae Hoon Roh; Sang Hyun Ryu; Myung Jun Park; Seong Bae An; Yong Gyu An; Hee Dong Jung; Jin Gyu Heo
- Web page: https://patentgrep.com/patent/US11897054B2

## CPC

- B23K 26/26: of rectilinear seams
- B23K 26/323: involving parts made of dissimilar metallic material
- B23K 26/0622: by shaping pulses
- B23K 26/22: Spot welding
- B23K 31/125: {Weld quality monitoring}
- H01M 50/536: characterised by the method of fixing the leads to the electrodes, e.g. by welding
- B23K 2101/36: Electric or electronic devices
- B23K 2103/10: Aluminium or alloys thereof
- B23K 2103/12: Copper or alloys thereof
- B23K 2103/18: Dissimilar materials
- B23K 2103/26: {Alloys of Nickel and Cobalt and Chromium}
- Y02E 60/10: Energy storage using batteries
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Embodiments relate to laser welding methods, monitoring methods, and monitoring systems for a secondary battery. A laser welding method for a secondary battery includes performing laser welding on a positive electrode base having a thin-film shape in which a plurality of positive electrode base tabs are formed at a side, a negative electrode base having a thin-film shape in which a plurality of negative electrode base tabs are formed at a side, and a thin-film multi-tab to be joined to each of the positive electrode base and the negative electrode base, a welded portion in which the multi-tab is welded with the positive electrode base and the negative electrode base being melting-joined by using a laser such that a plurality of welding spots is formed on the welded portion.

## Claims

### Claim 1

A laser welding method for a secondary battery, the method comprising:
performing laser welding on a positive electrode base having a thin-film shape, a negative electrode base having a thin-film shape, and a thin-film multi-tab, so that each of the positive electrode base and the negative electrode base is joined to the multi-tab,
wherein respective welded portions in which the multi-tab is welded with the positive electrode base and the negative electrode base are melting-joined by using a laser such that a plurality of welding spots is formed on each of the welded portions, and
determining whether a defect of the welded portions exists,
wherein the determining whether a defect of the welded portions exists comprises
irradiating the welded portions with light in a direction from a first surface toward a second surface opposite the first surface of the welded portions, collecting light transmitted through the welded portions to form a first inspection image, and determining whether a perforated defect of the welded portions exists by analyzing the first inspection image, and
irradiating the welded portions with light in a direction from the second surface toward the first surface, collecting light reflected by the welded portions to form a second inspection image, and determining whether a back bead defect of the welded portions exists by analyzing the second inspection image.

### Claim 2 (depends on 1)

The laser welding method of claim 1, wherein a front bead protruding in an embossed shape from a front surface of a welded portion of the welded portions and a back bead protruding in an embossed shape from a rear surface of the welded portion are formed in each of the welding spots.

### Claim 3 (depends on 2)

The laser welding method of claim 2, wherein the back bead has a diameter less than that of the front bead.

### Claim 4 (depends on 1)

The laser welding method of claim 1, wherein the multi-tab joined to the positive electrode base and the negative electrode base is made of a different material than that of at least one of the positive electrode base and the negative electrode base.

### Claim 5 (depends on 4)

The laser welding method of claim 4, wherein the welded portion of the negative electrode base has a shear strength of 4 kgf or less, and the welded portion of the positive electrode base has a shear strength of 2 kgf or less, and
wherein the shear strength allows all of the welded portions to be fractured.

### Claim 6 (depends on 1)

The laser welding method of claim 1, wherein a maximum shear strength of the welded portion of the negative electrode base is greater than a maximum shear strength of the welded portion of the positive electrode base.

### Claim 7 (depends on 1)

The laser welding method of claim 1, wherein the laser welding is performed using a laser output of 300 W.