Electrolyte impregnation method for secondary battery

Abstract

The present invention relates to a method for impregnating a secondary battery with an electrolyte, and more particularly to a method for impregnating a secondary battery with an electrolyte, comprising: accommodating a secondary battery in a pressure chamber; and adjusting an internal pressure of the pressure chamber, wherein the pressure adjusting step includes performing a pressing step and a pressure releasing step two or more times.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0007636, filed January 17, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a method for impregnating a secondary battery with an electrolyte, and more particularly, to a method for impregnating a secondary battery with an electrolyte by alternately performing a pressing step and a pressing-off step on a chamber containing a secondary battery and omitting a vacuum depressurization step of adjusting the pressure to below atmospheric pressure, thereby increasing the electrolyte impregnation rate and reducing the waiting time between steps, thereby contributing to improving the efficiency of the impregnation process. [Background technology]

[0003] Secondary batteries are an alternative energy source to fossil fuels, which cause air pollution, and are used in electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (P-HEVs), and energy storage devices (ESSs).

[0004] Currently, widely used types of battery cells include lithium-ion batteries, lithium polymer batteries, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, etc. These unit secondary battery cells are generally configured into battery modules by connecting multiple battery cells in series or parallel depending on the required output voltage or charge / discharge capacity.

[0005] Meanwhile, lithium secondary batteries can be classified into can-type secondary batteries, in which an electrode assembly is housed in a metal can, and pouch-type secondary batteries, in which an electrode assembly is housed in a pouch made of an aluminum laminate sheet, depending on the shape of the battery case.

[0006] Such a lithium secondary battery is manufactured by inserting an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode into a battery case, and then injecting a liquid electrolyte, i.e., an electrolyte solution.

[0007] The injected electrolyte solution permeates between the positive electrode, negative electrode, and separator that constitute the electrode assembly due to capillary force, but the porous separator has a fine structure, making it difficult for the electrolyte solution to permeate.

[0008] If the electrolyte is not sufficiently impregnated into the electrode assembly, the charging and discharging efficiency of lithium ions and the like will decrease, resulting in a decrease in battery performance and a capacity deviation between battery cells.

[0009] In this regard, Patent Document 1 discloses an electrolyte impregnation method including the steps of reducing the pressure of an electrolyte to a cell including an electrode assembly and supplying the electrolyte in a vapor state, condensing the vapor state electrolyte supplied to the cell, and impregnating the cell with the electrolyte in a vacuum atmosphere.

[0010] Furthermore, Patent Document 2 discloses an electrolyte impregnation method including the steps of placing a secondary battery having an electrode assembly with an electrolyte injected therein into an internal space of an impregnation chamber, pressing the internal space of the impregnation chamber to impregnate the electrode assembly with the electrolyte in a pressurized atmosphere for a predetermined pressing time, and reducing the pressure in the internal space of the impregnation chamber to impregnate the electrode assembly with the electrolyte in a vacuum atmosphere for a predetermined depressurization time.

[0011] That is, in the conventional technology for impregnating a battery cell with an electrolyte, after the electrolyte is injected, the process of depressurizing and pressing is also carried out.

[0012] However, due to the reduced pressure atmosphere and pressing, which is lower than atmospheric pressure, or the reduced pressure after pressing, the waiting time until each unit process starts is long, making it impossible to efficiently carry out the impregnation process.

[0013] Furthermore, in the case of a cylindrical secondary battery, as the size increases, the electrolyte impregnation may decrease at the center of the jelly-roll electrode assembly. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Korean Patent Publication No. 10-2016-0130646 [Patent Document 2] Korean Patent Publication No. 10-2019-0091048 Summary of the Invention [Problem to be solved by the invention]

[0015] In order to solve the above problems, an object of the present invention is to provide a method for impregnating a secondary battery with an electrolyte, which can improve the impregnation of the electrolyte.

[0016] Another object of the present invention is to provide a method for impregnating an electrolyte into a secondary battery, which can reduce standby time. [Means for solving the problem]

[0017] To achieve the above object, a method for impregnating an electrolyte into a secondary battery according to the present invention includes the steps of: placing a secondary battery in a pressure chamber; and adjusting an internal pressure of the pressure chamber, wherein the pressure adjusting step includes performing a pressing step and a pressing release step two or more times.

[0018] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the step of adjusting the pressure may include sequentially performing a first pressing step, a first pressing release step, a second pressing step, and a second pressing release step.

[0019] In addition, the method for impregnating an electrolyte solution for a secondary battery according to the present invention is characterized in that after the second pressing and releasing step, a third pressing and a third pressing and releasing step are further performed.

[0020] In addition, in the method for impregnating an electrolyte solution for a secondary battery according to the present invention, a fourth pressing step and a fourth pressing and releasing step may be further performed after the third pressing and releasing step.

[0021] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressing force in each of the first pressing step and the second pressing step is in the range of 600 kPa to 750 kPa.

[0022] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressure maintaining time in each of the first pressing step and the second pressing step is in the range of 60 seconds to 360 seconds.

[0023] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressing time in the second pressing step is set to be longer than the pressing maintenance time in the first pressing step.

[0024] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressing force in each of the first pressing step, the second pressing step, and the third pressing step is in the range of 600 kPa to 750 kPa.

[0025] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressure maintaining time in each of the first pressing step, the second pressing step, and the third pressing step is in the range of 60 seconds to 360 seconds.

[0026] In the method for impregnating an electrolyte solution for a secondary battery according to the present invention, the pressure maintaining time is set to be longer in the order of the first pressing step, the second pressing step, and the third pressing step.

[0027] In addition, the method for impregnating an electrolyte for a secondary battery according to the present invention is characterized in that it does not include a depressurizing step in which the pressure inside the pressure chamber is lower than atmospheric pressure.

[0028] In the method for impregnating an electrolyte into a secondary battery according to the present invention, the secondary battery is characterized in that it is cylindrical or prismatic.

[0029] The present invention also features a secondary battery impregnated by the above-described electrolyte impregnation method. [Effects of the Invention]

[0030] As described above, according to the method for impregnating an electrolyte into a secondary battery according to the present invention, the impregnation rate of the electrolyte can be increased by alternately performing a pressing step and a pressing release step on a chamber containing a secondary battery.

[0031] In addition, according to the method for impregnating an electrolyte for a secondary battery according to the present invention, the waiting time for each step can be reduced by omitting the vacuum depressurization step of adjusting the pressure to less than atmospheric pressure, thereby contributing to improving the efficiency of the impregnation process.

[0032] Furthermore, according to the method for impregnating an electrolyte for a secondary battery according to the present invention, the vacuum decompression step for adjusting the pressure to less than atmospheric pressure is omitted, thereby reducing the number of operation and management items of the device, thereby contributing to improving the working environment. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a perspective view of a chamber for impregnating an electrolyte. [Figure 2] FIG. 2 is a front view of the impregnation chamber shown in FIG. 1. [Figure 3] FIG. 2 is a side view of the impregnation chamber shown in FIG. 1. [Figure 4] FIG. 2 is a perspective view of a pallet that accommodates secondary batteries. [Figure 5] 1 is a photograph showing an exploded view of a battery cell after the impregnation process according to Example 1 is completed. [Figure 6] 10 is a photograph showing an exploded view of a battery cell after the impregnation process according to Example 2 is completed. [Figure 7] 10 is a photograph showing an exploded view of a battery cell after the impregnation process according to Example 3. [Figure 8] 10 is a photograph showing an exploded view of a battery cell after the impregnation process according to Example 4. [Figure 9] 10 is a photograph showing an exploded view of a battery cell after the impregnation process according to Example 5 is completed. [Figure 10] 10 is a photograph showing an exploded view of a battery cell after the impregnation process according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, with reference to the accompanying drawings, a detailed description will be given of an embodiment of the present invention that will enable a person skilled in the art to easily carry out the present invention. However, in describing the operation principle of the preferred embodiment of the present invention in detail, if it is determined that a detailed description of related well-known functions or configurations may unnecessarily obscure the gist of the present invention, such detailed description will be omitted.

[0035] Furthermore, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only a direct connection but also an indirect connection via another element therebetween. Furthermore, unless otherwise specified, "including a certain element" does not mean that other elements are excluded, but that other elements may also be included.

[0036] The method for impregnating an electrolyte solution for a secondary battery according to the present invention includes the steps of placing a secondary battery in a pressure chamber and adjusting the internal pressure of the pressure chamber, but does not include a vibration step in which the pressure inside the pressure chamber is equivalent to a pressure lower than atmospheric pressure.

[0037] Specifically, in the step of adjusting the pressure, it is preferable to carry out a pressing step and a pressing release step of lowering the pressure to near atmospheric pressure two or more times.

[0038] For example, the step of adjusting the pressure may be performed in sequence of a first pressing step, a first releasing step, a second pressing step, and a second releasing step.

[0039] As another example, a first pressing step, a first releasing step, a second pressing step, a second releasing step, a third pressing step, and a third releasing step may be performed in sequence.

[0040] As yet another example, a first pressing step, a first releasing step, a second pressing step, a second releasing step, a third pressing step, a third releasing step, a fourth pressing step, and a fourth releasing step can be performed sequentially.

[0041] Of course, it is obvious that the pressing and releasing steps can be further repeated after the fourth pressing and releasing step.

[0042] Meanwhile, the pressing force at each pressing step is preferably 600 kPa to 750 kPa. If it is less than 600 kPa, the electrolyte impregnation rate is low, and if it exceeds 750 kPa, the electrode assembly may be damaged or the manufacturing cost of the pressing chamber may increase significantly. Therefore, the pressing force is preferably within this range.

[0043] The pressure maintenance time at each pressure stage is 60 seconds to 360 seconds, and it is preferable that the pressure maintenance times at each pressure stage are similar, and it is more preferable that the pressure maintenance time becomes longer as the pressure stage progresses.

[0044] The secondary battery of the present invention is not particularly limited as long as it is a lithium secondary battery, and may be, for example, a cylindrical secondary battery, a prismatic secondary battery, or a pouch-type secondary battery.

[0045] FIG. 1 is a perspective view of a chamber for impregnating the electrolyte, FIG. 2 is a front view of the impregnation chamber shown in FIG. 1, and FIG. 3 is a side view of the impregnation chamber shown in FIG.

[0046] The chamber for impregnating the electrode assembly of the secondary battery with the electrolyte solution can be a chamber that can be raised and lowered as shown in Figures 1 to 3. Of course, there are no particular limitations on the chamber as long as it can press the secondary battery with a certain pressure and release the pressure.

[0047] As shown in Figures 1 to 3, the electrolyte impregnated chamber includes a chamber body 100 for accommodating a secondary battery, a chamber frame 200 that surrounds the chamber body 100, an air cylinder 300 for moving a portion of the chamber body 100 up and down, and a control unit 400 for operating the air cylinder 300.

[0048] First, the chamber body 100 is composed of a lower body 110 and an upper body 120. The lower body 110 may have a substantially circular plate-like structure. The upper body 120 is located above the lower body 110 and is movable up and down, and its overall shape may be a hemisphere or semi-ellipse with an open interior.

[0049] The upper surface of the lower body 110 accommodates a secondary battery for electrolyte impregnation, and pressure and release must be alternately performed. Therefore, it is preferable that the upper body 120 and the lower body 110 be fastened together to maintain airtightness so as to be isolated from the outside, and to have a fastening structure that will not separate even if a certain pressure is applied to the inside.

[0050] For example, although not shown in the drawings, the lower body 110 and / or the upper body 120 may have a port (not shown) for supplying gas into the chamber and pressing it at a certain pressure or for exhausting the gas to the outside.

[0051] The chamber frame 200 can include a vertical frame 210 , a horizontal frame 220 , a support plate 230 , and a guide frame 240 .

[0052] The vertical frames 210 are formed in pairs facing each other across the chamber body 100. Two vertical frames 210 are arranged on each side at a predetermined interval, so the total number of vertical frames 210 may be, but is not limited to, four.

[0053] The horizontal frame 220 is fixed to the top of the four vertical frames 210 and may have a substantially rectangular plate-like structure.

[0054] The support plate 230 is located between the horizontal frame 220 and the upper body 120, and moves up and down by the operation of the air cylinder 300 while fixing and supporting the upper body 120. Specifically, it has a plate-like structure similar to the horizontal frame 220, and the piston rods 350 are connected to the opposing side edges, while the upper body 120 is connected to the center bottom.

[0055] Therefore, when the piston rod 350 descends or ascends, the support plate 230 moves up and down together with the upper body 120 while hanging therefrom.

[0056] The guide frame 240 is for guiding the support plate 230 so that it can move up and down stably, and may be disposed so as to penetrate vertically through the support plate 230. In detail, the lower end of the guide frame 240 is in close contact with the ground downward, and the other end has a generally rod-like shape positioned so as to be in close contact with the bottom surface of the horizontal frame 220. There may be four guide frames 240 penetrating each corner of the horizontal frame 220, but the number of guide frames 240 can be increased or decreased as necessary.

[0057] The control unit 400 controls the supply and exhaust of gas to determine the operation of the air cylinder 300 .

[0058] Figure 4 is a perspective view of a pallet that houses secondary batteries B. The secondary batteries B housed in the pallet are in a state where the top is left open and electrolyte is poured into them, and any number of modifications are possible as long as they can house secondary batteries B.

[0059] The present invention will be described in more detail below with reference to examples and experimental examples. However, these examples are merely intended to aid in understanding the present invention, and are not intended to limit the scope of the present invention in any way.

[0060] Example 1 A pallet (see FIG. 4) containing a number of cylindrical secondary batteries 21700 with electrolyte injected therein was loaded onto the lower body having the configuration shown in FIG. 1, and then the upper body was lowered to tightly contact the lower body so that the cylindrical secondary batteries were isolated from the outside.

[0061] Thereafter, a first pressing step, a first pressure release step, a second pressing step, a second pressure release step, a third pressing step, and a third pressure release step were carried out in this order to impregnate the electrolyte.

[0062] In the first pressure step, nitrogen gas was supplied into the chamber until the internal pressure of the pressure chamber reached 680 kPa, and this was maintained for 180 seconds from the point at which 680 kPa was reached. In the first pressure release step, nitrogen gas was exhausted until the internal pressure of the chamber reached atmospheric pressure.

[0063] In the second pressure step, nitrogen gas was supplied into the chamber until the internal pressure of the pressure chamber reached 680 kPa, and this was maintained for 230 seconds from the point at which 680 kPa was reached. In the second pressure release step, nitrogen gas was exhausted until the internal pressure of the chamber reached atmospheric pressure.

[0064] In the third pressure step, nitrogen gas was supplied into the chamber so that the internal pressure of the pressure chamber reached 680 kPa, and this was maintained for 280 seconds from the point at which 680 kPa was reached. In the third pressure release step, nitrogen gas was exhausted so that the internal pressure of the chamber reached atmospheric pressure.

[0065] Example 2 The first pressing step, the first pressing release step, the second pressing step, the second pressing release step, the third pressing step, and the third pressing release step were carried out in that order, and the internal pressure in each of the first pressing step to the third pressing step was set to the same value of 650 kPa, and the maintenance time was also set to the same value of 180 seconds. The remaining steps were carried out in the same manner as in Example 1, and the electrolyte was impregnated.

[0066] Example 3 The electrolyte was impregnated in the same manner as in Example 1, except that the first pressing step, the first pressure release step, the second pressing step, the second pressure release step, the third pressing step, the third pressure release step, the fourth pressing step, and the fourth pressure release step were carried out in that order, and the internal pressure in each of the first pressing step to the fourth pressing step was set to the same 700 kPa and the maintenance time was also set to the same 120 seconds.

[0067] Example 4 The first pressing step, the first pressing release step, the second pressing step, the second pressing release step, the third pressing step, and the third pressing release step were carried out in that order, and the internal pressure in each of the first pressing step to the third pressing step was set to the same value of 700 kPa, and the maintenance time was also set to the same value of 180 seconds. The remaining steps were carried out in the same manner as in Example 1, and the electrolyte was impregnated.

[0068] Example 5 The steps were carried out in the order of a first pressing step, a first pressure release step, a second pressing step, a second pressure release step, a third pressing step, and a third pressure release step.

[0069] In the first pressing step, the internal pressure of the pressing chamber was 700 kPa and maintained for 360 seconds, in the second pressing step, the internal pressure of the pressing chamber was 700 kPa and maintained for 60 seconds, and in the third pressing step, the internal pressure of the pressing chamber was 700 kPa and maintained for 60 seconds, except that the remaining steps were the same as in Example 1, and the electrolyte was impregnated.

[0070] Comparative Example The electrolyte was impregnated by carrying out the first pressure reduction step, the first pressing step, the pressure release step, the second pressing step, the second pressure reduction step, the first pressure release step, the third pressure reduction step, and the second pressure release step in this order.

[0071] In the first decompression step, the air inside the chamber was evacuated to -90 kPa, which was maintained for 20 seconds. In the first compression step, nitrogen gas was supplied to the chamber until the internal pressure of the compression chamber reached 650 kPa, which was maintained for 200 seconds from the point at which 650 kPa was reached. In the compression release step, nitrogen gas was evacuated until the internal pressure of the chamber was the same as atmospheric pressure.

[0072] In the second pressing step, nitrogen gas was supplied into the chamber so that the internal pressure of the pressing chamber reached 650 kPa, and the pressure was maintained for 250 seconds after reaching 650 kPa.

[0073] In the second decompression step, the air inside the chamber was evacuated to -30 kPa and maintained at this pressure for 10 seconds, and in the first decompression release step, external air was introduced so that the pressure inside the chamber was the same as atmospheric pressure.

[0074] In the third decompression step, the air inside the chamber was evacuated to -30 kPa and maintained for 10 seconds, and in the second decompression release step, external air was introduced so that the pressure inside the chamber was the same as atmospheric pressure.

[0075] [Table 1]

[0076] [Test example] After the cylindrical battery cells were subjected to the electrolyte impregnation process under the conditions of the example and comparative example, they were disassembled, and the parts that were not impregnated with the electrolyte were visually inspected.

[0077] Fig. 5 is a photograph of an exploded view of a battery cell after the impregnation process according to Example 1, Fig. 6 is a photograph of an exploded view of a battery cell after the impregnation process according to Example 2, and Fig. 7 is a photograph of an exploded view of a battery cell after the impregnation process according to Example 3. Fig. 8 is a photograph of an exploded view of a battery cell after the impregnation process according to Example 4, and Fig. 9 is a photograph of an exploded view of a battery cell after the impregnation process according to Example 5. Fig. 10 is a photograph of an exploded view of a battery cell after the impregnation process according to the comparative example.

[0078] In FIGS. 5 to 10, the marked portions indicate the portions that were not impregnated with the electrolyte, and the remaining portions indicate the portions that were impregnated with the electrolyte.

[0079] Also, looking at the results of the comparative example shown in FIG. 10, it can be seen that a large area of ​​the separator was not wetted with the electrolyte when the jelly roll was unfolded.

[0080] On the other hand, Figures 5 to 9, which show the results of Examples 1 to 5, show that the area that was not wetted with the electrolyte was significantly reduced. In particular, as can be seen from Figures 5 and 8, when the maintenance time for each pressing step is set to be the same or when the maintenance time is set to be longer in the later pressing steps, the electrolyte impregnation rate is improved.

[0081] Those skilled in the art will appreciate that various applications and modifications within the scope of the present invention will be possible based on the above content. [Explanation of symbols]

[0082] 100 chamber fuselage 110 Lower fuselage 120 upper fuselage 200 Chamber Frame 210 Vertical Frame 220 horizontal frame 230 Support Plate 240 Guide Frame 300 air cylinder 310 Cylinder Tube 320 head cover 330 Rod Cover 350 piston rod 400 control section 500 pallets B Secondary battery L1 First gas pipe L2 Second gas pipe

Claims

1. placing a secondary battery in a pressing chamber; adjusting the pressure inside the pressure chamber; Including, The method for impregnating an electrolyte solution for a secondary battery, wherein the adjusting step includes performing the pressing step and the releasing step two or more times.

2. 2. The method of claim 1, wherein the adjusting step comprises sequentially performing a first pressing step, a first releasing step, a second pressing step, and a second releasing step.

3. 3. The method of claim 2, further comprising the steps of: performing a third pressing step and a third pressing and releasing step after the second pressing and releasing step.

4. 4. The method of claim 3, further comprising the steps of: performing a fourth pressing step and a fourth pressing and releasing step after the third pressing and releasing step.

5. 3. The method of claim 2, wherein the pressure in each of the first and second pressing steps is in the range of 600 kPa to 750 kPa.

6. 6. The method of claim 5, wherein the first pressing step and the second pressing step each have a pressing time ranging from 60 seconds to 360 seconds.

7. The method of claim 6, wherein the second pressing step is performed for a longer period of time than the first pressing step.

8. 4. The method of claim 3, wherein the pressing force in each of the first pressing step, the second pressing step, and the third pressing step is in the range of 600 kPa to 750 kPa.

9. 9. The method of claim 8, wherein the first pressing step, the second pressing step, and the third pressing step each have a pressing time ranging from 60 seconds to 360 seconds.

10. The method of claim 9, wherein the pressure maintaining times are set to be longer in the order of the first pressing step, the second pressing step, and the third pressing step.

11. 2. The method for impregnating a secondary battery with an electrolyte according to claim 1, wherein the method does not include a depressurization step in which the pressure inside the pressure chamber is lower than atmospheric pressure.

12. 2. The method for impregnating a secondary battery with an electrolyte according to claim 1, wherein the secondary battery is cylindrical or prismatic.

13. A secondary battery impregnated by the method for impregnating an electrolyte solution according to any one of claims 1 to 12.

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