WO2024128557A1

WO2024128557A1 - Device and method for manufacturing cap assembly of cylindrical secondary battery

Info

Publication number: WO2024128557A1
Application number: PCT/KR2023/017801
Authority: WO
Inventors: 김기범; 정동호; 장훈; 손세현; 안민희
Original assignee: 덕우전자주식회사
Priority date: 2022-12-14
Filing date: 2023-11-07
Publication date: 2024-06-20
Also published as: KR20240092492A

Abstract

The present invention relates to a device and a method for manufacturing a cap assembly of a cylindrical secondary battery, the device and the method being capable of detecting welding defects in real time while welding a vent and a CID filter.

Description

Cap assembly manufacturing device and manufacturing method for cylindrical secondary battery

The present invention relates to an apparatus and method for manufacturing a cap assembly of a cylindrical secondary battery, and to an apparatus and method for manufacturing a cap assembly of a cylindrical secondary battery that can detect welding defects in real time while welding a vent and a CID filter.

Conventional secondary batteries are classified according to the shape of the battery case into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or square metal can, and pouch-type batteries in which the electrode assembly is built in a pouch-shaped case of aluminum laminate sheet. do.

In addition, the electrode assembly built into the battery case is a power generating element capable of charging and discharging consisting of a stacked structure of anode/separator/cathode, and is a jelly-roll type wound with a separator between the long sheet-shaped anode and cathode coated with active material. It is classified into a stacked structure in which a plurality of anodes and cathodes of a certain size are sequentially stacked with a separator interposed.

Among them, jelly-roll type electrode assemblies are the most widely manufactured because they are easy to manufacture and have the advantage of high energy density per weight. Jelly-roll type electrode assemblies are usually manufactured as cylindrical secondary batteries.

However, during charging and discharging of a secondary battery, the jelly-roll type electrode assembly tends to be deformed as it undergoes repeated expansion and contraction. During this deformation process, stress is concentrated in the center, causing the electrode to penetrate the separator and contact the metal center pin, causing internal damage. A short circuit causes

Due to the heat generated by the internal short circuit, the organic solvent is decomposed and gas is generated, and the battery may rupture due to an increase in gas pressure within the secondary battery. This increase in gas pressure inside the secondary battery occurs even when an internal short circuit occurs due to an external shock. It can happen.

In order to solve the safety problems of secondary batteries as described above, the cap assembly of the cylindrical battery includes a vent to rupture when the pressure inside the secondary battery is high and discharge high-pressure gas to the outside, and a device to block the current when the internal pressure of the secondary battery rises. Safety elements such as CID (Current Interrupt Device) filter, which is a current blocking element, are provided.

Meanwhile, the CID filter is fixedly installed on the vent by welding, and is configured to break the CID filter from the welded portion when the internal pressure of the secondary battery increases. In this case, in a weak welding situation where the welded portion is not sufficiently formed by welding, the secondary battery When the internal pressure of the battery increases, the welded part may be separated from the vent along with the CID filter, which may cause the CID filter to not function properly.

Therefore, in the process of manufacturing the cap assembly of a cylindrical secondary battery, it is necessary to inspect the welding condition between the CID filter and the vent.

This kind of welding condition inspection can be done by selecting some of the manufactured products as test samples and then considering destructive testing such as torque measurement and cross-section confirmation. However, the problem is that a complete inspection is not possible and the inspection time is too long. there is.

The cap assembly manufacturing apparatus and manufacturing method for a cylindrical secondary battery according to an embodiment of the present invention aims to solve the following problems in order to solve the above-mentioned problems.

A cap assembly manufacturing device for cylindrical secondary batteries that can shorten the manufacturing time of cap assemblies for cylindrical secondary batteries and fundamentally prevent the shipment of defective welded products such as weak welding by performing a complete inspection of the welding status between the vent and CID filter in a short time. and providing a manufacturing method.

The problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned can be clearly understood by those skilled in the art from the description below.

An apparatus for manufacturing a cap assembly of a cylindrical secondary battery according to an embodiment of the present invention relates to an apparatus for manufacturing a cap assembly of a cylindrical secondary battery for welding a vent and a CID filter of a cylindrical secondary battery, wherein the vent and the cap assembly are disposed on the vent. A fixing unit that secures the CID filter; a laser welding unit disposed above the fixing unit and irradiating a laser for welding the vent and the CID filter; a temperature measuring unit disposed below the fixing unit to measure the temperature of the lower part of the vent; and a control unit that detects welding defects between the vent and the CID filter based on the temperature of the lower part of the vent measured by the temperature measurement unit.

The temperature measurement unit is preferably a thermal imaging camera or an infrared sensor.

The control unit includes an input unit that acquires the temperature of the lower part of the vent transmitted from the temperature measurement unit; A comparison unit that compares the obtained temperature of the lower part of the vent with a preset temperature; It is preferable to include a determination unit that determines whether the CID filter is weakly welded based on the comparison result of the comparison unit.

If the temperature of the lower part of the vent is lower than a preset temperature as a result of the comparison by the comparison unit, the determination unit preferably determines that the CID filter is weakly welded to the vent.

The control unit preferably further includes an output control unit that controls the laser output of the laser welding unit.

When the determination unit determines that the welding state between the CID filter and the vent is a weak welding state occurs continuously more than a preset number of times, the output control unit preferably increases the laser output of the laser welding unit.

A method of manufacturing a cap assembly of a cylindrical secondary battery according to an embodiment of the present invention relates to a method of manufacturing a cap assembly of a cylindrical secondary battery for welding a vent and a CID filter of a cylindrical secondary battery, wherein the vent and the cap assembly are disposed on the vent. A first step of fixing the CID filter on a fixing unit; A second step in which a laser welding unit disposed above the fixing unit irradiates a laser to weld the vent and the CID filter, while a temperature measuring unit disposed below the fixing unit measures the temperature of the lower portion of the vent; and a third step in which the control unit detects welding defects between the vent and the CID filter based on the temperature of the lower part of the vent measured by the temperature measurement unit.

The third step includes a 3a step in which the control unit obtains the temperature of the lower part of the vent from the temperature measurement unit; A 3b step in which the control unit compares the temperature of the lower part of the vent with a preset temperature; It is preferable that the control unit includes a 3c step of determining whether the CID filter is weakly welded based on the comparison result of the 3b step.

If it is confirmed in step 3b that the temperature of the lower part of the vent is lower than the preset temperature, step 3c is preferably a step in which the control unit determines that the CID filter is weakly welded to the vent.

The cap assembly manufacturing apparatus and manufacturing method for a cylindrical secondary battery according to an embodiment of the present invention detects in real time the temperature of the lower part of the vent, which is the position opposite to the laser welding position, during laser welding of the vent and CID filter, By being configured to detect welding defects such as weak welding based on the detected temperature, the effect of drastically shortening the inspection time and simultaneously enabling a complete inspection of the welding condition can be expected.

The effects of the present invention are not limited to those mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below.

1 is a conceptual diagram briefly showing a cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention.

Figure 2 is a block diagram showing an example of a control unit in the configuration of the cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention.

Figures 3 and 4 are images to explain simulation conditions for simulating temperature changes in the upper part of the CID filter and the lower part of the vent during laser welding.

Figure 5 is an image showing simulation results for the temperature of the CID filter and vent when laser welding is performed at an output of 190 W in a state of full contact between the CID filter and vent.

Figure 6 is an image showing simulation results for the temperature of the CID filter and vent when laser welding is performed at an output of 190 W in a state of partial contact between the CID filter and the vent.

Figure 7 is a graph showing simulation results of vent temperature change according to laser output during laser welding.

Figure 8 is a graph showing simulation results of the temperature change of the CID filter according to laser output during laser welding.

Figure 9(a) is a graph showing the temperature for each measurement point at the bottom of the vent during laser welding using a thermal imaging camera, and Figure 9(b) is a graph showing torque values for each measurement point after laser welding.

Figure 10(a) is a graph showing the temperature for each measurement point at the bottom of the vent during laser welding using an infrared temperature sensor, and Figure 10(b) is a graph showing torque values for each measurement point after laser welding.

Figure 11 is a block diagram showing another implementation of a control unit in the configuration of the cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention.

Figure 12 is a flow chart showing in time series a method of manufacturing a cap assembly for a cylindrical secondary battery according to an embodiment of the present invention.

FIG. 13 is a flow chart illustrating the third step of FIG. 12 in detail.

Figure 14 is a flow chart showing in time series a method of manufacturing a cap assembly for a cylindrical secondary battery according to another embodiment of the present invention.

Preferred embodiments according to the present invention will be described in detail with reference to the attached drawings, but identical or similar components will be assigned the same reference numbers regardless of reference numerals, and duplicate descriptions thereof will be omitted.

Additionally, when describing the present invention, if it is determined that a detailed description of related known technologies may obscure the gist of the present invention, the detailed description will be omitted. In addition, it should be noted that the attached drawings are only intended to facilitate easy understanding of the spirit of the present invention, and should not be construed as limiting the spirit of the present invention by the attached drawings.

Hereinafter, a cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention will be described with reference to FIGS. 1 to 11.

A cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention relates to a cap assembly manufacturing apparatus for a cylindrical secondary battery for welding the vent 10 and the CID filter 20 of the cylindrical secondary battery, as shown in FIG. As shown, it is configured to include a fixing unit 100, a laser welding unit 200, a temperature measuring unit 300, and a control unit 400.

The fixing unit 100 performs the function of fixing the vent 10 and the CID filter 20, which are components of the cap assembly of the secondary battery. As shown in FIG. 1, the CID filter 20 is placed on the upper part of the vent 10. is fixedly placed on the fixing unit 100 in a seated state.

The laser welding unit 200 is spaced apart from the upper part of the fixing unit 100 and performs the function of irradiating laser for welding the vent 10 and the CID filter.

This laser welding unit 200 is configured to irradiate a laser with a preset output, and a welding portion is formed along the outer peripheral area of the CID filter 20 laminated and fixed on the upper part of the vent 10 fixed to the fixing unit 100. It is preferable that the irradiation position of the laser is configured to be continuously variable.

The temperature measuring unit 300 is disposed below the fixing unit 100 and functions to measure the temperature below the vent 10, and is preferably a thermal imaging camera or an infrared sensor.

The control unit 400 performs a function of detecting welding defects between the vent 10 and the CID filter 20 based on the temperature of the lower part of the vent 10 measured by the temperature measurement unit 300.

An implementation example of such a control unit 400 may be configured to include an input unit 410, a comparison unit 420, and a determination unit 430, as specifically shown in FIG. 2.

The input unit 410 performs a function of acquiring the temperature of the lower part of the vent 10 transmitted from the temperature measurement unit 300, and the comparison unit 420 functions of comparing the obtained temperature of the lower part of the vent with a preset temperature. Perform.

The determination unit 430 performs the function of determining whether or not the CID filter 20 is weakly welded based on the comparison result of the comparison unit 420. Specifically, as a result of the comparison of the comparison unit 420, the lower part of the vent 10 is determined. If the temperature is lower than the preset temperature, the determination unit 430 determines that the CID filter 20 is weakly welded to the vent 10.

That is, in the cylindrical secondary battery cap assembly according to an embodiment of the present invention, when welding defects such as weak welding occur due to poor welding between the vent 10 and the CID filter 20, the CID filter 20 Since the heat generated by the laser irradiated to the upper surface is not properly transmitted to the vent 10 placed below, the temperature of the lower part of the vent 10 is lower than that of the good product, and based on this temperature, welding such as weak welding is performed. By being configured to detect defects, it is possible to inspect all cylindrical secondary battery cap assemblies being manufactured, and furthermore, the time required for inspection can be greatly shortened.

Hereinafter, the simulation of the temperature change in the lower part of the vent 10 according to the welding condition will be described with reference to FIGS. 3 to 8.

In the case of the simulation target, as shown in FIG. 3, only the welding area of the vent 10 and the CID filter 20 is extracted from the cap assembly and specified as a cylindrical shape with the CID filter 20 seated on the upper part of the vent 10. did.

At this time, the heat conduction effect was maintained by applying symmetry conditions rather than insulation conditions to the sides of the cylinder, and the cooling effect by external air was applied by applying flux conditions to the top and bottom surfaces of the cylinder.

A model in which there is no gap between the vent (10) and the CID filter (20) because the welding of the vent (10) and the CID filter (20) is properly performed is defined as a full contact model, and the welding of the vent (10) and the CID filter (20) is defined as a full contact model. In cases where the condition is incomplete, such as weak welding, as shown in FIG. 4, both components are separated by about 10 μm, but a model with a partially contacted area (W) was defined as a partial contact model.

At this time, the diameter of the partially contacted area (W) was set differently based on the laser output of the laser welding unit 200, specifically 0.5mm for 190W, 1.0mm for 210W, and 1.2mm for 230W. set.

Under the above simulation environment, an energy source equivalent to a 190 W laser in the form of a Gaussian beam with a radius of 13 um is applied to the upper surface of the CID filter 20, and the center is rotated parallel to the circumferential direction over time. After one rotation by applying the wobble method, the temperature distribution of the vent (10) and the CID filter (20) in the full contact model and the vent in the partial contact model when the heat source is located at the point (P) The temperature distributions of (10) and CID filter (20) are shown in Figures 5 and 6, respectively.

That is, in the full contact model, as shown in Figure 5, the temperature of the CID filter 20 to which the laser is applied and the temperature of the vent 10 disposed below the CID filter 20 are confirmed to be almost the same, but in the partial contact model, the temperature of the CID filter 20 to which the laser is applied is confirmed to be almost the same. In the model, it can be confirmed that the temperature of the vent 10 is lower than the temperature of the CID filter 20, as shown in FIG. 6.

Meanwhile, when irradiating the laser for welding to the upper part of the CID filter 20, checking the temperature of the lower part of the vent 10 according to the laser output, as shown in FIG. 7, the vent of the partial contact model ( 10) It can be seen that the lower temperature is low.

In addition, when checking the temperature of the upper surface of the CID filter 20 according to the laser output, it can be seen that the temperature of the upper surface of the CID filter 20 of the partial contact model is higher than that of the full contact model, as shown in FIG. 8. This is believed to be because heat conduction from the CID filter 20 to the vent 10 in the partial contact model is not as smooth as in the full contact model.

Hereinafter, in order to verify the accuracy of the welding defect detection method based on the temperature of the lower part of the vent 10 in the cap assembly manufacturing apparatus for cylindrical secondary batteries according to an embodiment of the present invention, the temperature of the lower part of the vent 10 was measured for the same sample. The results and torque measurement results will be described with reference to FIGS. 9 and 10.

Figure 9(a) shows the results of measuring the temperature at the bottom of the vent 10 with a thermal imaging camera in the process of welding the CID filter 20 and the vent 10 of 20 samples each using two different laser outputs. 9(b) shows the torque measurement results of samples welded through the process of FIG. 9(a).

Referring to FIGS. 9(a) and 9(b), it is confirmed that the sample with a relatively high measurement temperature at the bottom of the vent 10 also has a high torque value after welding, and conversely, the sample with a relatively high measurement temperature at the bottom of the vent 10 is relatively high. Considering that low-temperature samples were confirmed to have low torque values after welding, it was confirmed that there was a correlation between the measured temperature at the bottom of the vent 10 and the torque value.

However, when measuring the temperature of the lower part of the vent 10 using a thermal imaging camera, when laser welding is performed using the same output power as shown in FIG. 9(a), the maximum temperature difference between samples is about 117. It can be seen that there is a problem that the measurement range in ℃ is too wide.

Figure 10(a) shows the results of measuring the temperature at the bottom of the vent 10 with an infrared temperature sensor during the process of welding the CID filter 20 and the vent 10 of 10 samples each using three different laser outputs. 10(b) shows the torque measurement results of samples welded through the process of FIG. 10(a).

Referring to FIGS. 10(a) and 10(b), as in FIG. 9, it is confirmed that the sample with a relatively high measurement temperature at the bottom of the vent 10 also has a high torque value after welding, and conversely, the torque value at the bottom of the vent 10 is also high. Considering that the sample with a relatively low measurement temperature was confirmed to have a low torque value after welding, it was confirmed that the measurement temperature and torque value of the lower part of the vent 10 were correlated.

In particular, when measuring the temperature of the lower part of the vent 10 using an infrared temperature sensor, as shown in FIG. 10(a), when laser welding is performed using the same output power, the maximum temperature difference between samples is about 47. It is confirmed that the measurement range is stable compared to the thermal imaging camera in ℃.

Therefore, the measurement range can be formed relatively stably, and furthermore, it is desirable to apply an infrared sensor with a relatively fast measurement speed as the temperature measurement unit 300 to measure the temperature at the bottom of the vent 10, but the thermal imaging camera If better performance can be achieved compared to an infrared sensor due to differences in specifications and measurement methods, a thermal imaging camera may be applied.

Meanwhile, the cap assembly manufacturing apparatus for a cylindrical secondary battery according to an embodiment of the present invention is configured to detect welding defects while welding the CID filter 20 and the vent 10 as described above, and includes a plurality of caps. When assemblies are continuously input into the manufacturing equipment, the welding quality between the CID filter 20 and the vent 10 in each cap assembly can be continuously inspected.

In this process, if welding defects between the CID filter 20 and the vent 10 of the cap assembly that are continuously inputted by the determination unit 430 of the control unit 400 continuously occur more than a preset number of times, the laser welding unit It can be determined that the problem is caused by the low laser output of 200, and to solve this problem, a method of allowing the control unit 400 to automatically adjust the laser output can be considered.

To this end, the control unit 400 may further include an output control unit 440 as shown in FIG. 11, and this output control unit performs the function of controlling the laser output of the laser welding unit 200.

Specifically, when the judgment unit 430 of the control unit 400 continuously determines that the CID filter 20 is not properly welded to the vent 10 more than a preset number of times, the control unit 400 ) The output control unit 440 may be configured to increase the laser output of the laser welding unit 200.

Hereinafter, with reference to FIGS. 12 and 13, a method of manufacturing a cap assembly of a cylindrical secondary battery for welding the vent 20 and the CID filter 10 of the cylindrical secondary battery according to an embodiment of the present invention will be described. Descriptions of content that overlaps with content already described in the cap assembly manufacturing device for the mentioned cylindrical secondary battery will be omitted.

The method for manufacturing a cap assembly of a cylindrical secondary battery according to an embodiment of the present invention includes the first step (S100) of fixing the vent 10 and the CID filter 20, welding and venting (10), as shown in FIG. ) It is configured to include a second step (S200) of measuring the lower temperature and a third step (S300) of detecting welding defects.

Specifically, the first step (S100) is a step of fixing the vent 10 and the CID filter 20 disposed on the upper part of the vent 10 on the fixing unit 100, and the second step (S200) is fixing the vent 10 and the CID filter 20 disposed on the upper part of the vent 10. (100) The laser welding unit 200 placed at the top irradiates the laser to weld the vent 10 and the CID filter 20, while the temperature measurement unit 300 placed below the fixing unit 100 welds the vent 100. (10) This is the step of measuring the temperature of the lower part.

The third step (S300) is a step in which the control unit 400 detects welding defects between the vent 10 and the CID filter 20 based on the temperature of the lower part of the vent 10 measured by the temperature measurement unit 300. , This third step (S300) may be composed of three detailed steps as shown in FIG. 13.

Specifically, the 3a step (S310) in which the input unit 410 of the control unit 400 acquires the temperature of the lower part of the vent 10 from the temperature measurement unit 300, and the comparison unit 420 of the control unit 400 The 3b step (S320) of comparing the temperature of the lower part of the vent 10 with the preset temperature (T1) is sequentially performed.

Thereafter, a 3c step (S330) is performed in which the determination unit 430 of the control unit 400 determines whether the CID filter 20 is weakly welded based on the comparison result of the 3b step (S320).

In particular, if the temperature of the lower part of the vent 10 is confirmed to be lower than the preset temperature T1 in the above-described 3b step (S320), the 3c step (S330) is performed by the determination unit 430 of the control unit 400. This is the step of determining that the CID filter 20 is weakly welded to the vent 10, and good products and defective products are distinguished through this third c step (S330).

Hereinafter, a method for manufacturing a cap assembly of a cylindrical secondary battery according to another embodiment of the present invention will be described with reference to FIG. 14.

A method of manufacturing a cap assembly of a cylindrical secondary battery according to another embodiment of the present invention includes the first step (S100) to the third step (S300) of the method of manufacturing a cap assembly of a cylindrical secondary battery according to an embodiment of the present invention described above. All of the above are included, but the fourth step (S400) and the fifth step (S500) are configured to be additionally performed after the third step (S300).

In the fourth step (S400), the control unit 400 determines that the CID filter 20 has not been properly welded to the vent 10 by the determination unit 430, that is, a preset number of defects (N). This is the step to determine whether it occurs continuously in excess of .

If it is confirmed in the fourth step (S400) that the number of consecutive occurrences of defects exceeds the preset number (N), the fifth step (S500) is performed. The fifth step (S500) is specifically performed by the control unit 400. It may be defined as a step in which the output control unit 440 increases the laser output of the laser welding unit 200.

Above, the present invention has been described in detail using preferred embodiments, but the scope of the present invention is not limited to the specific embodiments and should be interpreted in accordance with the appended claims. Additionally, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

Claims

In the cap assembly manufacturing device for a cylindrical secondary battery for welding the vent and CID filter of the cylindrical secondary battery,

a fixing unit for fixing the vent and a CID filter disposed on an upper part of the vent;

a laser welding unit disposed above the fixing unit and irradiating a laser for welding the vent and the CID filter;

a temperature measuring unit disposed below the fixing unit to measure the temperature of the lower part of the vent; and

a control unit that detects welding defects between the vent and the CID filter based on the temperature of the lower part of the vent measured by the temperature measurement unit;

A cap assembly manufacturing device for a cylindrical secondary battery comprising a.
In claim 1,

A cap assembly manufacturing device for a cylindrical secondary battery, wherein the temperature measurement unit is a thermal imaging camera or an infrared sensor.
The method of claim 1, wherein the control unit,

an input unit that acquires the temperature of the lower part of the vent transmitted from the temperature measurement unit;

A comparison unit that compares the obtained temperature of the lower part of the vent with a preset temperature;

a determination unit that determines whether the CID filter is weakly welded based on the comparison result of the comparison unit;

A cap assembly manufacturing device for a cylindrical secondary battery comprising a.
In claim 3,

When the temperature of the lower part of the vent is lower than a preset temperature as a result of the comparison of the comparison unit, the determination unit determines that the CID filter is weakly welded to the vent.
In the method of manufacturing a cap assembly of a cylindrical secondary battery for welding the vent and CID filter of the cylindrical secondary battery,

A first step of fixing the vent and the CID filter disposed on the vent on a fixing unit;

A second step in which a laser welding unit disposed above the fixing unit irradiates a laser to weld the vent and the CID filter, while a temperature measuring unit disposed below the fixing unit measures the temperature of the lower portion of the vent; and

A third step in which a control unit detects welding defects between the vent and the CID filter based on the temperature of the lower part of the vent measured by the temperature measurement unit;

A method of manufacturing a cap assembly of a cylindrical secondary battery comprising a.
The method of claim 5, wherein the third step is,

Step 3a in which the control unit acquires the temperature of the lower part of the vent from the temperature measurement unit;

A 3b step in which the control unit compares the temperature of the lower part of the vent with a preset temperature;

A 3c step in which the control unit determines whether the CID filter is weakly welded based on the comparison result of the 3b step;

A method of manufacturing a cap assembly for a cylindrical secondary battery, comprising:
In claim 6,

If it is confirmed that the temperature of the lower part of the vent is lower than the preset temperature in step 3b,

The 3c step is a method of manufacturing a cap assembly of a cylindrical secondary battery, characterized in that the control unit determines that the CID filter is weakly welded to the vent.