KR102265847B1 - Device for Eliminating Gas from Activated Battery Cell - Google Patents

Abstract

The present invention is a device for removing gas inside a battery cell generated in the activation process of the battery cell,
a jig on which the battery cell that has undergone the activation process is mounted;
a vacuum suction unit for sucking internal gas by applying a vacuum from an unsealed end of the battery case; and
one or more rollers positioned on the top of the battery cell mounted on the jig to press the outer surface of the battery cell;
including,
The roller starts pressing at a portion spaced apart from the tab-lead coupling portion where the electrode tab and the electrode lead are welded based on the lead protrusion direction of the battery cell, and rotates and horizontally moves in the direction of the tab-lead coupling portion, the battery It provides a gas removal device, characterized in that sequentially pressurizing the outer surface of the cell.

Description

Device for Eliminating Gas from Activated Battery Cell}

The present invention relates to a gas removal device for an activated battery cell.

As technology development and demand for mobile devices increase, the demand for batteries as an energy source is rapidly increasing, and accordingly, a lot of research on batteries capable of meeting various needs is being conducted.

Typically, in terms of battery shape, there is a high demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to products such as mobile phones with thin thickness, and in terms of materials, they have advantages such as high energy density, discharge voltage, and output stability. Demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries is high.

In addition, secondary batteries are classified according to the structure of the electrode assembly of the positive electrode/separator/negative electrode structure. Typically, a jelly having a structure in which a long sheet-shaped positive electrode and negative electrode are wound with a separator interposed therebetween. -Roll (winding type) electrode assembly, stack type (stacked type) electrode assembly in which a plurality of positive and negative electrodes cut in units of a predetermined size are sequentially stacked with a separator interposed therebetween, positive and negative electrodes of a predetermined unit are interposed with a separator A stack-folding type electrode assembly having a structure in which bi-cells or full cells stacked in one state are wound.

Recently, a pouch-type battery having a structure in which a stack-type or stack-folding electrode assembly is embedded in a pouch-type battery case of an aluminum laminate sheet is attracting a lot of attention due to low manufacturing cost, small weight, easy shape deformation, etc. Also, its usage is gradually increasing.

Most secondary batteries, including these pouch-type batteries, undergo a process of activating the battery by charging and discharging during the manufacturing process of the battery cell. In order to manufacture the final battery cell, it is necessary to remove the gas generated in the activation process. This is called a degassing process.

A partial schematic diagram of a conventional degassing process is shown in FIG. 1 .

Referring to FIG. 1 , in some conventional techniques, the activated battery cell 10 is fixed to a die 20 , and a vacuum suction unit installed at the unsealed end 12-1 of the battery case 12 . A degassing process is performed by vacuum pressure in which the internal gas is sucked by applying a vacuum in step (21). However, in this case, in the battery cell 10 , an empty space exists in the tab-lead coupling portion 15 where the electrode tab 13 and the electrode lead 14 are welded to each other. By application, a shape (referred to as a 'Ravine part (A)') appears in which the battery case 12 of the tab-lead coupling part 15 enters in an inner direction in which the electrode assembly 11 is accommodated. At the same time, pressure is applied to the outside of the battery case 12 from the outer surface of the electrode assembly 11 from which the electrode tab 13 protrudes due to the reflective action by the formation of the Rabin part A, thereby applying a reaction force. ), a portion (B) in which the pouch shape of the battery cell is deformed occurs, and the gas in the deformed portion (B) is not sufficiently removed, and a portion that cannot be charged occurs in the electrode assembly 11 due to residual gas. There is a problem in that the initial capacity of the battery is lowered, and the swelling of the Rabin unit A increases according to the cycle of the battery cell 10 thereafter.

Accordingly, there is a high need for a technology capable of fundamentally solving these problems.

An object of the present invention is to solve the problems of the prior art as described above and the technical problems that have been requested from the past.

After repeated in-depth research and various experiments, the inventors of the present application, when performing a degassing process by applying a vacuum to remove the gas inside the battery cell generated in the activation process, tap-spaced apart from the lead coupling part In the case of applying a roller that rotates and horizontally moves in the direction of the tab-lead coupling part by starting pressurization at the site, even when the battery case is deformed at the part where the tab-lead coupling part is formed, the residual gas moves to the outer surface of the electrode assembly due to the reflection action. It was confirmed that the problem of the battery case being deformed to the outside and the residual gas problem could be solved, and the present invention was completed.

A gas removal device according to the present invention for achieving this object,

A device for removing gas inside a battery cell generated in the activation process of the battery cell,

a jig on which the battery cell that has undergone the activation process is mounted;

a vacuum suction unit for sucking internal gas by applying a vacuum from an unsealed end of the battery case; and

one or more rollers positioned on the top of the battery cell mounted on the jig to press the outer surface of the battery cell;

including,

The roller starts pressing at a location spaced apart from the tab-lead coupling part where the electrode tab and the electrode lead are welded based on the lead protrusion direction of the battery cell, and rotates and horizontally moves in the direction of the tab-lead coupling part, It is characterized in that the outer surface of the cell is pressed sequentially.

In general, when the gas inside the battery cell is removed by applying a vacuum as described above, as described above, by suction of the vacuum suction unit, the battery case at the portion where the tab-lead coupling portion of the battery cell is formed becomes the electrode assembly. It undergoes a shape deformation entering inwardly accommodated. At this time, in the case of the conventional method in which vacuum suction is simply performed, due to the shape deformation as described above, the gases present at the tab-lead coupling part are reflected from the deformation pressure in the inner direction of the battery case from the electrode assembly. As the tab protruded partially toward the upper surface of the electrode assembly, pressure was applied to the outside of the battery case, causing the pouch shape of the battery cell to deform and the overall thickness to increase. Such a problem may cause problems in that not only the appearance of the battery cell is deformed, but also swelling occurs due to the remaining gas thereafter, and the lifespan characteristics are deteriorated.

However, in the case of using the gas removal device according to the present invention, by suction of the vacuum suction unit, the battery case at the portion where the tab-lead coupling portion of the battery cell is formed undergoes a shape deformation in which the electrode assembly is accommodated in the inner direction, The deformation of the battery case from the upper surface of the electrode assembly to the outside according to the reflective action as described above does not occur.

This is when the tab-lead coupling part of the battery cell initiates pressurization, and when the battery cell rotates and horizontally moves in the direction of the tab-lead coupling part, a relatively large pressure acts inward for the reflection action, gas This is because it is not pushed to the part and is removed by vacuum suction because it exists in the tab-lead coupling part. Therefore, it is preferable that the pressing force by the roller is greater than the pressure applied to the reflective action corresponding to the shape deformation of the tab-lead coupling part due to vacuum suction.

Specifically, in one example, when the tab-lead coupling portion is formed on one side of the battery cell, the roller may rotate and horizontally move from the other side of the outer surface of the battery cell where the tab-lead coupling portion is not formed to the one side, Alternatively, it may rotate and horizontally move from the middle portion of the battery cell to the one side.

Here, the middle portion is a concept encompassing both ends, ie, except for the ends of one side and the other side, from the center of the battery cell to the portion spaced apart by a predetermined distance.

That is, when the tab-lead coupling part is formed on only one side of the battery cell, the empty space in the battery case generated by the coupling part is formed only on one side, and the shape of the battery case is deformed inside by vacuum suction (Rabin ( Ravine) portion is also made from one side, so that the roller is rotated and horizontally moved in the one direction at a distance spaced apart from one side of the electrode assembly where the tab-lead coupling portion is located, and the starting point is not limited.

Similarly in this respect, in another example, when the tab-lead coupling portion is respectively formed on one side of the battery cell and the other side opposite thereto, the Rabin portion may be formed on both one side and the other side, both on both sides. Since it is necessary to press all the parts that can be deformed in the outward direction by the reflective force, there are two rollers, and the tab-lead coupling part is formed in the middle part of the battery cell, respectively, the one side and the other side It can be rotated horizontally to each side.

In any of the above cases, the starting point is not limited as long as it is spaced apart from one side (the other side) of the electrode assembly where the tab-lead coupling part is located, but in a state where vacuum suction is in progress, the tab-lead coupling part is located on the side It is preferable that the pressing force of the roller is continued at the end of the electrode assembly.

Accordingly, the pressing of the roller may be started simultaneously with gas removal by the vacuum suction unit and continued until the gas removal is completed, or may be started during the gas removal process by the vacuum suction unit and continued until the gas removal is completed.

And, when the removal of the gas by the vacuum suction unit is completed, the roller may end the pressing on the outer surface of the battery cell at a position corresponding to the end of the electrode assembly from which the electrode tabs protrude.

In this case, the pressing force of the roller is the same as the sum of the pressure in the vertical direction and the rotational force of the roller, and as described above, it is preferable that the combined pressing force is greater than the pressure due to the reflection action of the Rabin part deformation.

On the other hand, the size of the roller may have a length equal to or greater than the width of the battery cell, specifically, the size of the roller may be 100% to 120% of the width of the battery cell.

The width of the battery cell means the size in a direction perpendicular to the direction in which the tab protrudes from the electrode assembly, and the length of the roller means the height of the cylinder, not the radial direction of the circle.

If the size of the roller is smaller than the width of the battery cell, deformation may occur outside the battery case as described above in an area where the roller cannot pressurize, and in this case, it is not preferable because it is difficult to completely solve the conventional problem. not.

In addition, the gas removal device according to the present invention is useful when the battery cell is a pouch-type battery cell in which an electrode assembly is embedded in a pouch-type case of a laminate sheet including a metal layer and a resin layer, and the gas removal process is performed by vacuum application. More useful in the case of gas inhalation.

In one specific example, the metal layer constituting the laminate sheet may be a metal layer so as to exhibit a function of improving the strength of the case in addition to the function of preventing the inflow or leakage of foreign substances such as gas and moisture, and the metal layer, For example, it may be one selected from the group consisting of aluminum, iron, copper, tin, nickel, cobalt, silver, stainless, and titanium, or an alloy thereof, but is not limited thereto.

The resin layer includes an inner sealant layer present on the inner surface in the direction of the electrode assembly, and an outer coating layer present on the outer surface, based on the metal layer.

Here, the inner sealant layer has thermal adhesion (thermal adhesion), low hygroscopicity to suppress the penetration of electrolyte, and is made of a thermally fusible polymer that does not expand or corrode by the electrolyte, and the thermal adhesion property The polymer may be polyolefin, and more preferably, non-stretched polypropylene (cPP).

Since the outer coating layer has to have excellent resistance from the external environment, it is made of a weather-resistant polymer having a predetermined or higher tensile strength and weather resistance, and the weather-resistant polymer may be polyethylene phthalate (PET), polyethylene naphthalate (PEN) or nylon.

In the degassing device according to the present invention, when the degassing process is performed by applying a vacuum to remove the gas generated inside the battery cell during the activation process, the tap-starting pressurization is performed at a portion spaced apart from the lead coupling part to initiate the tap -By applying a roller that rotates and moves horizontally in the direction of the lead coupling part, the change in the outer direction of the battery case appears as the residual gas moves to the outer surface of the electrode assembly due to the reflection action of the Rabin part formation in the area where the tab-lead coupling part is formed. Since the problem can be solved, it is easy to manage the entire thickness of the battery cell, and since no gas remains in the region, swelling is reduced and lifespan characteristics are improved.

1 is a schematic diagram of a process in which degassing is performed by a conventional degassing apparatus;
2 is a schematic diagram of a process in which degassing is performed by a degassing apparatus according to an embodiment of the present invention;
3 is a schematic diagram of a process in which degassing is performed by a gas removal device according to another embodiment of the present invention.

Hereinafter, although described with reference to the drawings according to an embodiment of the present invention, this is for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

2 schematically shows a process in which degassing is performed by a gas removal device according to an embodiment of the present invention.

Referring to these drawings, the gas removal device according to the present invention applies a vacuum from the unsealed end 121 of the jig 200 on which the battery cell 100 that has undergone the activation process is mounted and the battery case 120, It has a structure including a vacuum suction unit 210 for sucking internal gas, and a roller 220 positioned on the upper portion of the battery cell 100 mounted on the jig 200 to press the outer surface of the battery cell 100 . have.

At this time, the battery cell 100 has a structure in which the electrode assembly 110 in which the electrode tabs 111 protrude from one side is embedded in the battery case 120 , and the electrode lead 130 is disposed at the end of the electrode tabs 111 . is welded to form the tab-lead coupling part 140 , and an empty space exists inside the battery case 120 in which the tab-lead coupling part 140 is located.

Although only one type of tab is illustrated in FIG. 2 , tabs of different polarities also protrude in the width direction of the electrode assembly and are connected to electrode leads corresponding to these polarities.

After the battery cell 100 is mounted on the jig 200 of the gas removal device, the vacuum suction unit 210 applies a vacuum from the unsealed end 121 of the battery case 120 to start the suction of the internal gas. do.

By the vacuum application of the vacuum suction unit 210, the tab-lead coupling unit 140 is formed, the battery case 120 is sucked inward in which the electrode assembly 110 is accommodated, and the Ravine unit ( R) is formed.

On the other hand, in the gas removal device according to the present invention, at the same time or after the vacuum suction, the roller 220 pressurizes from any part of the outer surface of the battery cell 100 at a location spaced apart from the Rabin part R. Started, the tab-lead coupling unit 140 rotates and horizontally moves in the direction to press the battery cell 100, and the battery cell 100 at a position corresponding to the end of the electrode assembly 110 from which the electrode tabs 111 protrude. Pressing on the outer surface of the ends.

At this time, the pressure of the roller 220 is continued until the gas removal by the vacuum suction unit 210 is completed. That is, even if the roller 220 reaches the end of the electrode assembly 9110, which is the end point of the pressing while the gas removal by the vacuum suction unit 210 is continued, the roller 220 continues to rotate while the horizontal movement is stopped and the pressing force to keep

Therefore, in the case of using the gas removal device according to the present invention, it is possible to solve the problem of deformation of the battery case in the outward direction, which appears while the residual gas moves to the outer surface of the electrode assembly due to the reflection action according to the formation of the Rabin part R. .

Similarly, FIG. 3 schematically shows a process in which degassing is performed by a gas removal device according to another embodiment of the present invention.

Referring to FIG. 3 , as compared with FIG. 2 , only the electrode tabs protrude from both sides of the electrode assembly.

Specifically, the gas removal device is a vacuum suction for sucking internal gas by applying a vacuum from the unsealed end 321 of the jig 400 on which the battery cell 300 that has undergone the activation process is mounted and the battery case 320 . It has a structure including parts 410 and 411 and rollers 420 and 421 positioned on the upper part of the battery cell 300 mounted on the jig 400 to press the outer surface of the battery cell 300 .

At this time, the battery cell 300 has a structure in which the electrode assembly 310 in which the electrode tabs 311 and 312 protrude from one side and the other side opposite to it is built-in in the battery case 320, and the electrode tabs 311 and 312 ), electrode leads 330 and 331 are welded to the ends, respectively, to form tab-lead coupling portions 340 and 341 at both sides. The electrode tabs 311 and 312 protrude in the same direction with the same polarity, respectively. That is, when the electrode tabs 311 are positive electrode tabs, the electrode tabs 312 are negative electrode tabs, and may be opposite, and the electrode leads 330 and 331 are welded to each other with the same polarity as the electrode tabs.

Meanwhile, the degassing process by applying a vacuum proceeds similarly to FIG. 2 . However, since the tab-lead coupling portions 340 and 341 are formed on both sides of the electrode assembly 310, empty spaces exist on both sides, and thus, the vacuum suction units 410 and 411 apply a vacuum on both sides. to perform a degassing process. Accordingly, the Rabin parts R' and R'' as a modified form of the battery case 320 by vacuum suction are also formed on both sides.

Therefore, in this case, in order to exert the effect according to the present invention, two rollers 420 and 421 are required, and at the same time as vacuum suction, or after that, the Rabin parts (R, R') are spaced apart from each other. At the center of the outer surface of the battery cell 100, the two rollers 420 and 421 start pressing and rotate and horizontally move in the opposite direction to move in the direction of the tab-lead coupling portions 340 and 341 on both sides, respectively, and the battery cell ( 300), and at positions corresponding to both ends of the electrode assembly 310 from which the electrode tabs 311 and 312 protrude, respectively, the pressing on the outer surface of the battery cell 300 is terminated.

At this time, the pressing form of the rollers 420 and 421 is the same as described with reference to FIG. 2 .

Therefore, even in such a structure, when the gas removal device according to the present invention is used in this structure, the problem of deformation of the battery case in the outward direction appears while the residual gas moves to the outer surface of the electrode assembly due to the reflection action according to the formation of the Rabin part (R). can solve

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

<Production Example>

_{90 wt% of LiCoO 2} as a cathode active material, 5.0 wt% of Denka Black as a conductive material, and 5.0 wt% of PVdF as a binder were added to NMP as a solvent and mixed to prepare a cathode mixture, and the cathode was placed on an aluminum foil having a thickness of 20 μm. After coating the mixture to a thickness of 200 μm, rolling and drying were performed to prepare a positive electrode.

As an anode active material, 95 wt% of artificial graphite, 1.5 wt% of a conductive material (Super-P), and 3.5 wt% of a binder (PVdF) were put in NMP, a solvent, and mixed to prepare a negative electrode mixture, and a 20 μm thick copper foil After coating the negative electrode mixture to a thickness of 200 ㎛, rolling and drying the negative electrode was prepared.

After interposing a porous polyethylene separator between the positive electrode and the negative electrode, _{an electrolyte solution containing 1M LiPF 6} dissolved in carbonate solvent of EC: EMC = 1: 2 was injected to prepare a lithium secondary battery.

After charging the lithium secondary battery prepared as described above at 4.4 V under 0.1C conditions, the process of discharging to 2.5 V was performed once.

<Example 1>

The lithium secondary battery prepared in Preparation Example was subjected to a degassing process for 14 seconds under a vacuum condition of 100 kPa using a gas removal device to which a roller was applied as in the present invention.

<Comparative Example 1>

The lithium secondary battery prepared in Preparation Example was subjected to a degassing process for 14 seconds under a vacuum condition of 100 kPa using a gas removal device to which a conventional roller was not applied.

<Experimental Example 1>

After completing the degassing process in Example 1 and Comparative Example 1, the initial thickness of the battery cell was measured, and the results are shown in Table 1 below.

Referring to Table 1, it can be seen that the thickness of the battery cell according to the present invention is reduced compared to the case of using the conventional gas removal device.

This is because, as described above, the problem in which the thickness is irregularly increased by pushing the pouch toward the upper direction of the electrode assembly by the reflective action is solved, so that the deviation has a reduced thickness level.

<Experimental Example 2>

In Example 1 and Comparative Example 1, the unsealed portion of the secondary battery in which degassing was completed was sealed to complete manufacturing, and then the lifespan characteristics were evaluated. The lifespan characteristic evaluation was performed under the conditions of 0.8C ↔ 1C (one-time charge/discharge) between 4.4V and 2.5V. The lifespan characteristics were evaluated from the discharge capacity retention rate and thickness increase rate, and the discharge capacity retention rate expressed the capacity after repeated charging and discharging 100 times as a percentage of the initial capacity, and the thickness increase rate was the initial thickness after 100 repetitions. It is expressed as a percentage ratio with respect to the thickness. The results are shown in Table 2.

Referring to Table 2, when the gas removal device according to the present invention is used, it can be seen that the lifespan characteristics of the battery cells are at the same level and are improved in terms of swelling.

This is because, as confirmed in Experimental Example 1, since the thickness level with a reduced deviation is reduced, swelling during charging and discharging is reduced, and the influence applied to the electrode assembly is small.

Although the above has been described with reference to the drawings and experimental examples according to the embodiment of the present invention, it is possible for those of ordinary skill in the art to make various applications and modifications within the scope of the present invention based on the above contents. will be.

Claims (11)

A device for removing gas inside a battery cell generated in the activation process of the battery cell,
a jig on which the battery cell that has undergone the activation process is mounted;
A plurality of vacuum suction units for sucking the internal gas by applying a vacuum from each of the unsealed both ends of the battery case; and
a plurality of rollers moving in different directions from the top of the battery cell mounted on the jig to press the outer surface of the battery cell;
including,
Based on the lead protrusion direction of the battery cell, the electrode tab and the electrode lead are welded, the tab-lead coupling portion is formed on one side of the battery cell and the other side opposite to it, respectively,
By the suction of the vacuum suction part, the battery case at the portion where the tab-lead coupling part of the battery cell is formed undergoes a contraction deformation in which the electrode assembly is accommodated, and the reflective action of the contraction deformation is applied to the battery case from the outer surface of the battery cell. Protruding deformation occurs when pressure is applied in the outward direction,
Some of the rollers press the portion where the protruding deformation occurs while rotating and horizontally moving from the middle portion of the battery cell to the tab-lead coupling portion on one side of the battery cell, and the other portion is the battery cell in the middle portion of the battery cell. A gas removal device, characterized in that while rotating and horizontally moving to the tab-lead coupling part of the other side, the portion in which the protruding deformation occurs is pressed downward. delete delete delete delete According to claim 1, wherein the roller is a gas removal device, characterized in that the end of the pressure on the outer surface of the battery cell at a position corresponding to the end of the electrode assembly from which the electrode tabs protrude. The gas removal apparatus according to claim 1, wherein the pressing of the roller starts at the same time as the gas removal by the vacuum suction unit and continues until the gas removal is completed. The gas removal apparatus according to claim 1, wherein the pressing of the roller is started during the gas removal process by the vacuum suction unit and continues until the gas removal is completed. The gas removal apparatus according to claim 1, wherein the pressing force of the roller is equal to the sum of the pressure in the vertical direction and the rotational force of the roller. 10. The gas removal device according to claim 9, wherein the roller has a length equal to or greater than the width of the battery cell. The gas removal device according to claim 1, wherein the battery cell is a pouch-type battery cell in which an electrode assembly is embedded in a pouch-type case of a laminate sheet including a metal layer and a resin layer.

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