KR102264674B1 - Electrolyte Injection Method Using Vacuum - Google Patents

Abstract

The present invention is a method of injecting an electrolyte into a battery cell in which an electrode assembly is built in and an electrolyte injection port communicating with the inside is perforated,
(a) preparing a chamber filled with an electrolyte;
(b) positioning the electrolyte injection port of the battery cell to be immersed in the electrolyte in the chamber;
(c) depressurizing the atmosphere in the chamber to remove gas inside the battery cell; and
(d) pressurizing the atmosphere of the chamber so that the electrolyte moves into the battery cell;
It relates to an electrolyte injection method comprising a.

Description

Electrolyte Injection Method Using Vacuum

The present invention relates to an electrolyte injection method using a vacuum.

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.

The lithium secondary battery is manufactured by injecting an electrolyte solution in a state in which an electrode assembly composed of a positive electrode and a negative electrode and a separator interposed between the positive electrode and the negative electrode is accommodated in a battery case and then sealed.

The electrolyte provides a path for the movement of ions and may affect the performance of the battery, and as the battery is repeatedly charged and discharged, the electrolyte may be depleted or the battery life may be deteriorated due to a change in its distribution, etc. have.

As described above, the injection of the electrolyte is an important factor in determining the lifespan characteristics of the battery, and it is required to inject the electrolyte as quickly as possible in the production process of the battery.

Conventionally, as an electrolyte injection method commonly used, there are an atmospheric pressure injection method and a centrifugal injection method.

The atmospheric injection method is performed by gradually injecting an alkaline electrolyte into the battery can in which the electrode assembly is housed under the condition of atmospheric pressure. However, as the concentration of the electrolyte increases, the conductivity increases, but the fluidity decreases, so the penetration rate of the electrolyte into the electrode plate is slow. There is a problem in that the total injection time is long and the productivity is low.

In addition, the centrifugal injection method injects an electrolyte solution using a centrifugal injector, but there is a problem in that the equipment configuration is complicated and expensive, and since the injection amount of the electrolyte is low, the performance of the battery is deteriorated.

Accordingly, there is a high need for a new electrolyte injection method capable of increasing the injection amount of the electrolyte while shortening the injection time of the electrolyte.

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, as will be described later, for the battery cell in which the electrode assembly is housed in the prismatic metal can, the electrolyte injection port of the battery cell is positioned so that it is immersed in the electrolyte in the chamber In the case of injecting the electrolyte while performing the process of decompressing and pressurizing the atmosphere of the chamber, it is possible to suppress the gas from flowing into the battery cell during the electrolyte injection process, so the swelling of the battery cell is prevented. It has been found that it can be prevented and the present invention has been completed.

The electrolyte injection method according to the present invention for achieving this object,

As a method of injecting an electrolyte into a battery cell having an electrode assembly embedded therein and an electrolyte injection port communicating with the interior is perforated,

(a) preparing a chamber filled with an electrolyte;

(b) positioning the electrolyte injection port of the battery cell to be immersed in the electrolyte in the chamber;

(c) depressurizing the atmosphere in the chamber to remove gas inside the battery cell; and

(d) pressurizing the atmosphere of the chamber so that the electrolyte moves into the battery cell;

may include.

In the case of a pouch-type lithium secondary battery, in a state in which a portion of the sealing portion is left in an unsealed state, the electrolyte is injected through the unsealed portion and the electrolyte is injected in a manner to seal and seal the unsealed portion. Therefore, there is an aspect that the injection process of the electrolyte is relatively simple.

On the other hand, in the case of a prismatic lithium secondary battery, when an injection nozzle is attached to the electrolyte injection port, the inside of the can is evacuated through the exhaust means of the electrolyte injection device, and a predetermined amount of electrolyte is supplied through the injection nozzle, the atmospheric pressure inside the can A method in which the electrolyte is injected into the can by the pressure difference between the pressure and the atmospheric pressure is used. The injection speed of the electrolyte is slow, and unnecessary gas is injected together during the injection process of the electrolyte, causing the battery cell to swell during the activation process of the battery. There are problems that occur.

However, as in the electrolyte injection method of the present application, without attaching a separate nozzle to the electrolyte injection port, when the electrolyte is injected through the process of depressurizing and pressurizing the atmosphere of the chamber in a state where the injection port is directly immersed in the electrolyte , it is possible to prevent unnecessary gas from entering the inside of the battery cell, and there is an advantage that the injection amount of the electrolyte can be increased, so that the conventional problems as described above can be solved.

The battery cell may have a structure including a prismatic metal can having a built-in electrode assembly and an open top, and a top cap mounted on the open top of the metal can and having an electrolyte injection hole perforated, the top The electrolyte may be injected while the battery cell is positioned so that the electrolyte injection hole formed in the cap is immersed in the electrolyte filled in the chamber.

In one specific example, since the steps (c) and (d) may be performed in a state that the electrolyte injection port of the battery cell is immersed in the electrolyte, the electrolyte injection port only serves as a passage for the electrolyte, It is possible to prevent unnecessary gas affecting the activation process of the battery cell from moving into the battery cell together with the injected electrolyte.

In order to inject the electrolyte into the battery cell, the process of removing the gas inside the battery cell must be preceded. When the inside of the chamber is in a vacuum state or an atmospheric pressure lower than atmospheric pressure is reached, the gas inside the battery cell is It may be discharged to the outside of the battery cell. Accordingly, the process (c) may convert the atmosphere of the chamber to a vacuum state to reduce the pressure, or the process (c) may convert the atmosphere of the chamber to an atmospheric pressure lower than atmospheric pressure to reduce the pressure.

For example, in the process (c), the pressure may be reduced by converting the atmosphere of the chamber to 0.01 bar to 0.5 bar, and specifically, the pressure may be reduced by converting the atmosphere to 0.01 bar to 0.2 bar.

If the atmosphere of the chamber is greater than 0.5 bar, the difference with atmospheric pressure may not be completely discharged from the inside of the battery cell, and if it is less than 0.01 bar, the time for decompression may be long, thereby shortening the injection process. It is undesirable because it can deviate from the purpose for doing so.

However, the degree and time of the decompression in the process (c) may be controlled by the amount of the electrolyte required for injection. Specifically, as the amount of electrolyte required for injection increases, the degree of decompression may increase and the decompression time may be lengthened. On the other hand, as the amount of electrolyte required for injection decreases, the degree of decompression may decrease and the decompression time may be shortened.

In addition, in consideration of the amount of electrolyte required for injection, if necessary, the lowest pressure-reduced state may be maintained for a certain period of time.

On the other hand, the process (d) is a process for moving the electrolyte into the battery cell from which the gas has escaped through the process (c). When the pressure inside the chamber is increased, the electrolyte is returned to the space inside the battery cell from which the gas is discharged. This movement bar, because the injection is made while the electrolyte injection port is immersed in the electrolyte, only the electrolyte flows into the battery cell, and it is possible to prevent the gas unnecessary for activating the battery cell from moving to the battery cell.

Accordingly, the process (d) may be pressurized by converting the atmosphere of the chamber to atmospheric pressure, or the process (d) may be pressurized by converting the atmosphere of the chamber to an atmospheric pressure relatively higher than atmospheric pressure.

For example, the process (d) may be pressurized by converting the atmosphere of the chamber to 1.5 bar to 5 bar, specifically, it may be pressurized by converting it to 2 bar to 5 bar.

In the case where the atmosphere of the chamber is converted to higher than 5 bar in the process (d) and pressurized, the time required for pressurization may increase, so the manufacturing process may be lengthened, and in the case of less than 2 bar, the electrolyte is transferred to the center of the electrode assembly. This is undesirable as the time required for complete impregnation may increase.

In one specific example, in a battery cell in which electrolyte is injected by the electrolyte injection method according to the present invention, the battery cell is disassembled immediately after the injection of the electrolyte is completed, and the electrode assembly is taken out and the separation membrane is separated. When measuring the impregnated area of the separator, Since the electrolyte impregnation rate is fast, the impregnated area of the separator may be 80% or more based on the total area of the separator.

The present invention provides a battery cell manufactured by the electrolyte injection method.

The present invention also provides a battery pack including the battery cell as a unit cell and a device including the battery pack as a power source.

Specifically, the battery pack may be used as a power source for devices requiring high temperature stability, long cycle characteristics, high rate characteristics, etc., and specific examples of such devices include a mobile device, a wearable device, and the like. , a power tool powered by a battery-based motor to move; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and the like; electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters (E-scooter); electric golf carts; and a power storage system, but is not limited thereto.

Since the medium-large battery module is composed of including a plurality of battery cells, and accordingly, the cost of the members used for manufacturing the battery cell greatly affects the manufacturing cost of the entire battery module, the secondary battery according to the present invention is such a medium and large-sized battery module. It can be particularly preferably applied to the battery module.

Since the structures of these devices and their manufacturing methods are known in the art, detailed description thereof will be omitted herein.

As described above, in the electrolyte injection method according to the present invention, for a battery cell in which an electrolyte injection port communicating with the interior in which the electrode assembly is embedded is perforated at the top of a rectangular metal can, the electrolyte injection port is positioned so as to be immersed in the electrolyte In the case of injecting the electrolyte through the process of depressurizing and pressurizing the battery in a state in which the electrolyte is injected, it is possible to prevent gas from flowing into the battery cell during the electrolyte injection process, and thus, swelling of the battery cell can be prevented.

1 is a schematic diagram of an exploded perspective view of a prismatic battery;
2 is a schematic diagram showing a state in which the electrolyte injection port is positioned so as to be immersed in the electrolyte according to one embodiment;
3 is a schematic diagram schematically showing an electrolyte injection method according to the present invention;
4 is a photograph showing the degree of impregnation of the separator immediately after injection of the electrolyte according to Example 1;
5 is a photograph showing the degree of impregnation of the separator immediately after injection of the electrolyte according to Comparative Example 1; and
6 is a photograph of a separator in a state completely immersed in an electrolyte.

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.

FIG. 1 is a schematic diagram of a prismatic battery having a jelly-roll type electrode assembly embedded therein.

Referring to FIG. 1 , the prismatic battery 50 has a top cap 30 in which an electrode assembly 10 is built in a prismatic metal case 20 and a negative terminal 32 is formed at an open top of the case 20 . ) is a combined structure.

The negative electrode of the electrode assembly 10 is electrically connected to the lower end of the negative terminal 32 on the top cap 30 through the negative electrode tab 12 , and such negative terminal 32 is connected to the top cap by an insulating member 34 . insulated from (30). On the other hand, the other electrode of the electrode assembly 10 is electrically connected to the top cap 30 whose positive electrode tab 14 is made of a conductive material such as aluminum and stainless steel, thereby forming a positive electrode terminal by itself.

In addition, in order to ensure an electrically insulating state between the electrode assembly 10 and the top cap 30 except for the electrode tabs 12 and 14 , a sheet-shaped insulating member 40 is disposed between the prismatic case 20 and the electrode assembly 10 . ) is inserted, the top cap 30 is mounted, and the top cap 30 and the case 20 are joined together by welding along the contact surface. Then, after injecting the electrolyte through the electrolyte injection port 43, a metal ball (not shown) is welded and sealed, and the battery is completed by coating the welding site with epoxy or the like.

2 schematically shows a state in which the electrolyte injection port is positioned so as to be immersed in the electrolyte according to the electrolyte injection method of the present invention.

Referring to FIG. 2 , the electrolyte 102 is filled in the chamber 101 capable of controlling the atmospheric pressure of the internal atmosphere, and the chamber 101 is reduced in pressure so that the internal atmosphere becomes a vacuum state, or is pressurized to reach an atmospheric pressure higher than atmospheric pressure. It is a chamber that can be sealed.

The battery cell 50 of FIG. 1 is positioned such that the electrolyte injection port 43 formed in the top cap is immersed in the electrolyte 102. In this state, the gas inside the battery cell is discharged by performing a process of depressurizing the chamber atmosphere. It can be discharged to the outside of the battery cell, and when the chamber atmosphere is pressurized again, only the electrolyte moves into the battery cell, and gases other than the electrolyte can be prevented from entering the battery cell.

3 is a schematic diagram schematically showing an electrolyte injection method according to the present invention.

Referring to FIG. 3 , the electrolyte injection method according to the present invention includes (a) preparing a chamber filled with electrolyte, (b) positioning the electrolyte injection port of the battery cell to be immersed in the electrolyte in the chamber, (c) It consists of a process of depressurizing the atmosphere of the chamber in order to remove gas inside the battery cell, and (d) a process of pressurizing the atmosphere of the chamber so that the electrolyte moves into the battery cell.

The chamber of the process (a) has a structure that can be sealed in a state in which the electrolyte is filled, and the processes (c) and (d) are performed while the electrolyte injection port of the battery cell is immersed in the electrolyte.

The process (c) converts the atmosphere of the chamber into a vacuum state or 0.01 bar to 0.5 bar that is relatively lower than atmospheric pressure, and the process (d) is, the atmosphere of the chamber is changed to atmospheric pressure or 1.5 bar to 1.5 bar relatively higher than atmospheric pressure. Convert to 5 bar and pressurize.

When the electrolyte is injected through the above processes (a) to (d), the time required for the impregnation of the electrolyte may be reduced.

Hereinafter, the present invention will be described with reference to examples, which are for easier understanding of the present invention, and the scope of the present invention is not limited thereto.

<Example 1>

A jelly-roll type electrode assembly is accommodated in a metal prismatic battery case having an electrolyte injection port formed therein, and the battery cell is sealed to prevent material movement in the remaining parts except for the electrolyte injection port.

An electrolyte solution is filled in a chamber capable of accommodating a battery cell and the pressure of the atmosphere inside the chamber can be controlled, and the electrolyte injection port of the battery cell is positioned so as to be submerged in the electrolyte.

While maintaining the state in which the electrolyte injection port is immersed in the electrolyte, the atmosphere of the chamber is changed to 0.1 bar and the pressure is reduced for 1 minute.

After the decompression state, the atmosphere of the chamber is changed to 5 bar and pressurized for 5 minutes, and then the electrolyte injection hole is sealed to complete the electrolyte injection process.

Immediately after the injection was completed, the battery cell was disassembled to separate the separator impregnated with the electrolyte, and a photograph showing the impregnation of the separator is shown in FIG. 4 .

Referring to FIG. 4 , in the separation membrane 200 , a portion 201 in which electrolyte wetting is made can be confirmed from the outer periphery toward the center, but the center is observed as the electrolyte non-impregnated portion 202 . In addition, it is confirmed that wetting of the electrolyte is also made in the bent portion 203 of the jelly roll type electrode assembly.

As such, it can be seen that the area of the electrolyte-impregnated portion is about 5/6 or more based on the total area of the separator.

<Comparative Example 1>

After attaching an injection nozzle to the electrolyte injection port and connecting an exhaust means to one end of the injection nozzle to create a vacuum inside the battery case, the electrolyte is supplied and the electrolyte flows into the can by the pressure difference between the atmospheric pressure and the atmospheric pressure inside the can. The electrolyte is injected in the injection method.

Immediately after the injection was completed, the battery cell was disassembled to separate the separator impregnated with the electrolyte, and a photograph showing the impregnation of the separator is shown in FIG. 5 .

Referring to FIG. 5 , in the separation membrane 300 , a portion 301 in which electrolyte wetting is made can be confirmed from the outer periphery toward the center, but the center is observed as the electrolyte non-impregnated portion 302 . In addition, it is confirmed that wetting of the electrolyte is also made in the bent portion 303 of the jelly roll type electrode assembly.

As such, it can be seen that the area of the electrolyte-impregnated portion is about 2/3 of the total area of the separator.

Comparing FIG. 5 with FIG. 4, the area of the electrolyte non-impregnated portion 202 of Example 1 is narrower than the area of the electrolyte non-impregnated portion 302 of Comparative Example 1, and the electrolyte is impregnated as in Example 1. In this case, it can be seen that the electrolyte impregnation rate is higher.

<Experimental Example 1>

In the battery cell in which the electrolyte was injected in the same manner as in Example 1 and Comparative Example 1, like the separator shown in FIG. 6 , the time it took for the entire separator to be impregnated with the electrolyte was measured, and the results are shown in Table 1 below.

Impregnation time (min) Example 1 90 Comparative Example 1 110

As such, in the electrolyte injection method according to the present invention, the initial electrolyte impregnation rate is higher than that of the conventional method, and the time required for electrolyte impregnation can be shortened, thereby improving processability.

Those of ordinary skill in the art to which the present invention pertains will be able to perform various applications and modifications within the scope of the present invention based on the above contents.

Claims (12)

A method of injecting electrolyte into a battery cell including a prismatic metal can having an electrode assembly embedded therein, an open top, and a top cap mounted on the open top of the metal can and having an electrolyte injection hole perforated therein,
(a) preparing a chamber filled with an electrolyte;
(b) positioning the electrolyte injection port of the battery cell to be immersed in the electrolyte in the chamber;
(c) depressurizing the atmosphere in the chamber to remove gas inside the battery cell; and
(d) including the process of pressurizing the atmosphere of the chamber so that the electrolyte moves into the battery cell,
The process (c) and process (d) are electrolyte injection method, characterized in that performed in a state that the electrolyte injection port of the battery cell is immersed in the electrolyte. delete delete The method of claim 1, wherein in the step (c), the pressure in the chamber is converted into a vacuum state to reduce the pressure. The method of claim 1, wherein in the step (c), the pressure is reduced by converting the atmosphere of the chamber to an atmospheric pressure relatively lower than atmospheric pressure. The method of claim 5, wherein in the step (c), the pressure of the chamber is changed to 0.01 bar to 0.5 bar to reduce the pressure. The method according to claim 1, wherein the degree and time of the decompression in the step (c) is controlled by the amount of the electrolyte required for the injection. The method of claim 1, wherein in the step (d), the atmosphere of the chamber is converted to atmospheric pressure and pressurized. The method of claim 1 , wherein in the step (d), the atmosphere of the chamber is converted to an atmospheric pressure relatively higher than atmospheric pressure and pressurized. 10. The method of claim 9, wherein in the step (d), the atmosphere of the chamber is converted to 1.5 bar to 5 bar and pressurized. The method according to claim 1, wherein the impregnated area of the separator separated from the battery cell disassembled immediately after the completion of the electrolyte injection is 80% or more based on the total area of the separator. delete

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