KR-20260063901-A - Method for joining electrode tabs and lead tabs and secondary battery module manufactured thereby, secondary battery pack and vehicle including the secondary battery module

KR20260063901AKR 20260063901 AKR20260063901 AKR 20260063901AKR-20260063901-A

Abstract

The present invention provides a method for joining an electrode tab and a lead tab of a lithium secondary battery, characterized by performing a preliminary welding of the electrode tab using non-contact welding, performing tab cutting, and performing a main welding of the electrode tab and the lead tab using contact welding.

Inventors

송지은

Assignees

주식회사 엘지에너지솔루션

Dates

Publication Date: 20260507
Application Date: 20241031

Claims (10)

A method for joining the electrode tab and lead tab of a lithium secondary battery, Characterized by performing the preliminary welding of the electrode tab as non-contact welding, performing tab cutting, and performing the main welding of the electrode tab and the lead tab as contact welding. Method of joining electrode tabs and lead tabs.
In claim 1, The above lead tab is, It includes a lead formed of lithium metal and a lead film locally located on one or both sides of the lead, A portion of the above lead is joined so as to overlap with a portion of the above electrode tab, Method of joining electrode tabs and lead tabs.
In claim 1, The above non-contact welding is laser welding, Method of joining electrode tabs and lead tabs.
In claim 3, The above laser welding is, This is performed by a laser scanner head configured to irradiate a laser beam onto the electrode tab of an electrode assembly, and The laser beam emitted from the laser scanner head is incident perpendicularly on the electrode tab, Method of joining electrode tabs and lead tabs.
In claim 1, The above contact welding is ultrasonic welding, Method of joining electrode tabs and lead tabs.
In claim 5, The above ultrasonic welding is, Performed through an ultrasonic welder comprising a horn and anvil in the portion where the lead and the electrode tab overlap, Method of joining electrode tabs and lead tabs.
In claim 6, The above ultrasonic welding is performed by positioning the overlapping portion of the lead and the electrode tab on the flat surface of the anvil and pressing and vibrating the overlapping portion of the lead and the electrode tab with the horn so that spot welding is performed at the point of contact between the overlapping portion of the lead and the electrode tab and the horn. Method of joining electrode tabs and lead tabs.
A secondary battery module having a plurality of secondary batteries manufactured by a method of joining an electrode tab and a lead tab according to any one of claims 1 to 7.
A secondary battery module according to claim 8 and a pack case in which a plurality of said secondary battery modules are provided and stored, Secondary battery pack.
A secondary battery pack comprising the secondary battery pack according to claim 9, automobile.

Description

Method for joining electrode tabs and lead tabs and secondary battery module manufactured thereby, secondary battery pack and vehicle including the secondary battery module The present invention relates to a method for joining an electrode tab and a lead tab, a secondary battery module manufactured thereby, a secondary battery pack including such a secondary battery module, and an automobile. Specifically, the invention relates to a method for joining an electrode tab and a lead tab of a secondary battery using lithium metal as a lead tab, a secondary battery module manufactured thereby, a secondary battery pack including such a secondary battery module, and an automobile. As interest in energy storage technology continues to grow, research and development on electrochemical devices are gradually increasing as application fields expand to include mobile phones, tablets, laptops, and camcorders, as well as electric vehicles (EVs) and hybrid electric vehicles (HEVs). Electrochemical devices are the field receiving the most attention in this regard, and among them, the development of lithium secondary batteries, such as rechargeable lithium-sulfur batteries, is becoming the focus of interest. Furthermore, recently, research and development on new electrode and battery designs has been conducted to improve capacity density and specific energy in the development of such batteries. When manufacturing such lithium secondary batteries, welding operations are performed to bind tabs between unit electrodes to obtain an output suitable for the application, and at this time, a process of joining electrode tabs and lead tabs is carried out. Figure 1 is a diagram showing the state in which an electrode tab and a lead tab are joined in a typical secondary battery, and Figure 2 is a plan view of a lead tab joined to an electrode tab in a typical secondary battery. As shown in FIG. 1, a general secondary battery requires an electrode tab (positive tab or negative tab, 2) to electrically connect the positive plate and the negative plate constituting the electrode assembly (1) to an external device, and this electrode tab (2) is joined to a lead tab (positive lead tab or negative lead tab, 3) as shown in FIG. 2 by welding. Additionally, the lead tab (3) includes a metal lead (3a) and a lead film (3b) locally located on one or both sides thereof as shown in FIG. 2, and the metal lead (3a) located on one side thereof is joined to overlap with the electrode tab. Lithium-sulfur batteries, which are attracting attention as next-generation rechargeable batteries capable of replacing lithium-ion batteries, utilize only pure lithium metal (Li-metal) in the negative electrode without using a separate current collector. In other words, the negative electrode of a lithium-sulfur battery consists solely of lithium. In lithium-sulfur batteries, which have the characteristic of inducing a catholyte reaction from sulfur in the anode and lithium metal in the cathode, the biggest bottleneck during the life cycle is swelling of the anode and cathode. In particular, during charging and discharging, lithium metal undergoes a significant increase in thickness due to the formation of pores and dendrites caused by the deposition and desorption reactions of lithium ions. During this process, excess electrolytes enter the locally enlarged pores, ultimately leading to an electrolyte deficiency, which results in a rapid deterioration of lifespan. Due to these causes, lithium metal, which lacks a current collector, is easily damaged, and if it continues to deteriorate, even the negative tab—which has relatively weaker physical properties compared to the negative electrode of a lithium-ion battery (LIB)—is damaged, ultimately leading to a short circuit even with a minor impact. In the case of sulfur batteries using lithium metal as the negative electrode, problems such as lithium tearing, spreading, and stretching caused by the low rigidity of lithium metal, as well as adhesion occurring during lithium contact, must be resolved. FIG. 3 is a diagram illustrating a method of joining electrode tabs and lead tabs of a secondary battery according to the prior art. The joining of the electrode tab (2) and lead tab (3) of a secondary battery according to the prior art proceeds in the order of ultrasonic welding (preliminary welding) → tab cutting → laser welding (main welding) as shown in FIG. 3. Drawing symbol 1 indicates an electrode assembly, and drawing symbol 2a indicates a portion of the electrode tab (2) that has been ultrasonically welded. In this way, in the conventional preliminary welding, ultrasonic welding of the electrode tab (2) is performed, and in the main welding, laser welding is performed by overlapping the electrode tab (2) and the lead tab (3). 3a is the lead of the lead tab (3), 3b is the lead film, and 3c is a processed hole created by overlapping the lead (3a) with the ultrasonic welded part (2a) and then laser welding. Figure 4 is a sc