Degassing apparatus and degassing method

Abstract

A degassing apparatus according to one embodiment of the present invention is a apparatus for degassing gas inside a battery cell after an activation process of the battery cell including an electrode assembly, and may include a degassing pre-processing section provided for irradiating the battery cell with microwaves to vibrate and heat the gas inside the battery cell, and a degassing section provided for piercing the gas pockets of the battery cell after microwave irradiation and vacuum-suctioning the gas through the piercing sites.

Description

Technical Field

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[0001] The present invention relates to a degassing device and a degassing method, and more particularly, to a degassing device and a degassing method that perform a degassing process for removing gas in a battery cell after a degassing pretreatment that induces the molecular movement of the gas in the battery cell.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0131630 filed on October 4, 2023, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

Background Art

[0003] FIG. 1 is a perspective view of a pouch-type battery cell (10).

[0004] The manufacturing stage of the pouch-type battery cell (10) can include an assembly stage, an activation process, and a degassing stage.

[0005] Referring to FIG. 1, the battery cell (10) includes an electrode assembly (20), a pouch (30), and an electrolyte (40). The electrode assembly (20) is formed by sequentially laminating a negative electrode (21), a separator (22), a positive electrode (23), and a separator (22). In the electrode assembly (20), the negative electrode (21) and the positive electrode (23) are separated by the separator (22) and laminated so as to contact both surfaces of the separator (22).

[0006] In the assembly stage of the battery cell (10), the electrode assembly (20) is housed in the pouch (30). Then, the electrolyte (40) is injected into the cup portion of the pouch (30). Next, the edge of the pouch (30) is sealed so that the electrode assembly (20) and the electrolyte (cont'd)

[0007] FIG. 2 is a diagram for explaining the gas flow flowing through the lifted space of the electrode assembly in the activation process.

[0008] In the activation process described above, the battery cell (10) is activated by repeatedly charging, aging, and discharging several times. The purpose of activating the battery cell (10) is to stabilize the battery structure and make it usable.

[0009] In the activation process, the battery cell (10) is placed upright in an activation device (not shown) with the gas pocket (39) facing upwards, and both sides of the electrode assembly (20) are pressurized and charged / discharged.

[0010] When the battery cell (10) is activated, a large amount of gas (G) is generated in the internal space of the battery cell (10). As shown in Figure 3, this gas (G) increases the pressure in the internal space of the battery cell (10) and causes the volume of the battery cell (10) to expand.

[0011] Referring to the enlarged view in Figure 2, when the battery cell (10) expands due to the internal pressure caused by the gas (G), the negative electrode (21) and the separator membrane (22), or the separator membrane (22) and the positive electrode (23), which were in contact with each other, may float up. During the activation process, the gas (G) inside the battery cell (10) can flow through the floating space (24) within the electrode assembly (20).

[0012] The battery cell (10) is aged after the activation process, but at this time, the gas (G) that has flowed into the electrode assembly (20) may become sluggish in molecular motion and stagnate in the floating space (24).

[0013] Figure 3 is a diagram illustrating the gas (G) distribution within the battery cell (10) after the activation process.

[0014] Referring to Figure 3, the gas (G) inside the battery cell (10) can be divided into pocket gas (G1) collected in the gas pocket (39) and stagnant gas (G2) that remains in the electrode assembly (20).

[0015] The battery cell (10) is aged and then degassed. The degassing step is to remove gas (G) from within the battery cell (10).

[0016] During the degassing phase, pocket gas (G1) can be easily removed by the vacuum pressure provided within the battery cell (10).

[0017] However, the negative electrode (21), separation membrane (22), and positive electrode (23) of the electrode assembly (20) act as interfering factors that obstruct the flow of vacuum pressure, and stagnant gas (G2) may remain in the battery cell (10) even after the degassing stage.

[0018] Furthermore, as shown in Figure 2, during the activation process, the gas (G) that has permeated the electrolyte (40) is less likely to be drawn in by the vacuum pressure during the degassing stage and may remain in the battery cell.

[0019] Residual gas within battery cells affects their performance and lifespan. The more residual gas a battery cell contains, the lower its performance and the shorter its lifespan. [Overview of the Initiative] [Problems that the invention aims to solve]

[0020] The present invention was devised to solve the above-mentioned problems, and aims to provide a degassing apparatus and degassing method that can reduce the amount of residual gas in the battery cell after degassing by performing a degassing step to remove gas from the battery cell after a degassing pretreatment that induces molecular motion of gas in the battery cell. [Means for solving the problem]

[0021] The degassing device according to an embodiment of the present invention is a device for degassing the gas inside a battery cell after the activation process of the battery cell including an electrode assembly. In order to vibrate and heat the gas inside the battery cell, it is provided with a degassing pretreatment unit configured to irradiate the battery cell with microwaves, and after the irradiation of the microwaves, it can include a degassing unit configured to pierce the gas pocket of the battery cell and vacuum-suck the gas through the piercing site.

[0022] The degassing pretreatment unit can be provided to irradiate microwaves with a variable frequency.

[0023] In one embodiment, the degassing pretreatment unit can be provided to irradiate microwaves with a variable frequency within a predetermined range.

[0024] Also, the frequency can be variable within the range of 2.45 GHz to 7 GHz.

[0025] Also, the degassing pretreatment unit can be provided to irradiate the microwaves while changing the irradiation time according to the frequency range.

[0026] Also, the degassing pretreatment unit can be provided to irradiate the microwaves while maintaining the irradiation time in the same manner according to the frequency range.

[0027] Also, the degassing pretreatment unit can be provided to irradiate the microwaves while increasing the frequency. The degassing pretreatment unit can be provided to irradiate the microwaves while increasing the frequency within a predetermined range (for example, within the range of 2.45 GHz to 7 GHz).

[0028] Further, the degassing pretreatment unit can be provided to irradiate the microwave while decreasing the frequency. The degassing pretreatment unit can be provided to irradiate the microwave while decreasing the frequency within a predetermined range (for example, within the range of 2.45 GHz to 7 GHz).

[0029] Further, the degassing pretreatment unit can be provided to irradiate the microwave while periodically increasing and decreasing the frequency within a predetermined range.

[0030] Further, the degassing pretreatment unit can include a chamber unit provided with a chamber space in which the battery cell is accommodated, a microwave irradiation unit disposed in the chamber space for irradiating a microwave at a predetermined frequency, and a pretreatment control unit for controlling the operating power and operating time of the microwave irradiation unit so that the gas in the battery cell is heated to a preset temperature.

[0031] Further, the operating power may be in the range of 0.1 times to 0.3 times the maximum power.

[0032] Further, the degassing device can include a gas measurement unit provided to measure the amount of gas in the battery cell.

[0033] Further, the degassing unit can include a piercing unit provided to pierce the gas pocket, a suction unit fluidly movably connected to the piercing site, applying a vacuum pressure to the piercing site, using the piercing site as a gas discharge passage, and provided to suck the gas in the battery cell, and a sealing unit provided to seal the piercing site.

[0034] Furthermore, a degassing method according to one embodiment of the present invention is a method using the degassing apparatus, and the degassing method is for degassing gas inside a battery cell after an activation process of the battery cell including an electrode assembly, and may include a degassing pretreatment step of irradiating the battery cell with microwaves to vibrate and heat the gas inside the battery cell, and a degassing step of piercing the gas pockets of the battery cell after microwave irradiation, vacuum sucking out the gas through the piercing sites, and removing the gas inside the battery cell.

[0035] In the degassing pretreatment step, the microwaves vibrate and heat the stagnant gas that has accumulated in the electrode assembly, allowing the stagnant gas to flow from the stagnant region of the electrode assembly into the internal space of the battery cell.

[0036] Furthermore, during the degassing pretreatment step, the microwaves vibrate and heat the electrolyte in the battery cell, causing the gas contained in the electrolyte to vaporize and flow from the electrolyte into the internal space of the battery cell.

[0037] In one embodiment, the degassing pretreatment step can be configured to irradiate with microwaves at a variable frequency within a predetermined range.

[0038] Furthermore, during the degassing preprocessing stage, the frequency can be varied within the range of 2.45 GHz to 7 GHz.

[0039] Furthermore, in the degassing pretreatment step, the microwave irradiation can be configured to vary the irradiation time according to the frequency range.

[0040] Furthermore, in the degassing pretreatment step, the irradiation time can be maintained similarly according to the frequency range, and the microwaves can be irradiated.

[0041] Furthermore, the degassing pretreatment step can be configured to irradiate the microwave while increasing the frequency. The degassing pretreatment unit can be configured to irradiate the microwave while increasing the frequency within a predetermined range (for example, in the range of 2.45 GHz to 7 GHz).

[0042] Furthermore, the degassing pretreatment step can be configured to irradiate the microwaves while decreasing the frequency. The degassing pretreatment unit can be configured to irradiate the microwaves while decreasing the frequency within a predetermined range (for example, in the range of 2.45 GHz to 7 GHz).

[0043] Furthermore, in the degassing pretreatment step, the microwaves can be irradiated while periodically increasing or decreasing the frequency within a predetermined range. [Effects of the Invention]

[0044] As described above, the degassing apparatus and degassing method using the same, according to one embodiment of the present invention, have the following effects.

[0045] Through a degassing pretreatment process for battery cells, the degassing process is performed by heating and vibrating the gas and electrolyte inside the battery cells using variable frequency microwaves, thereby removing gases that have escaped from the electrode assembly and electrolyte along with gases that have been captured in the gas pockets.

[0046] By performing degassing after the degassing pretreatment on the battery cell, gases collected in the gas pockets, gases that remain in the electrode assembly after activation, and gases absorbed by the electrolyte during activation can be removed, thereby improving gas removal efficiency and reducing the amount of residual gas in the battery cell after degassing.

[0047] Furthermore, the amount of residual gas in the battery cell can be reduced by approximately 10% to 15% compared to conventional battery cells that do not undergo degassing pretreatment.

[0048] Furthermore, reducing the amount of residual gas in the battery cells can improve the performance of the battery cells and extend their lifespan. [Brief explanation of the drawing]

[0049] [Figure 1] This is a perspective view of a pouch-type battery cell.

[0050] [Figure 2] This diagram illustrates the flow of gas through the space above the electrode assembly during the activation process.

[0051] [Figure 3] This diagram illustrates the gas distribution within a battery cell after the activation process.

[0052] [Figure 4] This is a diagram showing the configuration of a degassing device according to one embodiment of the present invention.

[0053] [Figure 5] This is a diagram showing the configuration of a degassing preprocessing unit according to one embodiment of the present invention.

[0054] [Figure 6] This figure illustrates the molecular motion of gas in a degassed battery cell in one embodiment of the present invention.

[0055] [Figure 7] This diagram illustrates the flow of stagnant gas in the stagnant region shown in Figure 6 during the degassing pretreatment.

[0056] [Figure 8]This figure illustrates the process of degassing a battery cell that has undergone degassing pretreatment according to one embodiment of the present invention. [Modes for carrying out the invention]

[0057] Hereinafter, with reference to the attached drawings, a degassing apparatus according to one embodiment of the present invention and a degassing method using the same will be described.

[0058] Figure 4 is a diagram showing the configuration of a degassing apparatus according to one embodiment of the present invention, and Figure 5 is a diagram showing the configuration of a degassing preprocessing unit according to one embodiment of the present invention.

[0059] Figure 6 is a diagram illustrating the molecular motion of gas in a degassing pre-treated battery cell (10a) in one embodiment of the present invention, and Figure 7 is a diagram illustrating the flow of stagnant gas in the stagnant region of Figure 6 during degassing pre-treatment.

[0060] Referring to Figures 2, 3, 4, and 5, a degassing apparatus (100) according to one embodiment of the present invention is an apparatus for degassing gas (G) inside a battery cell (10) after an activation process of the battery cell (10) including an electrode assembly (20), and may include a degassing pre-processing section (200) provided to irradiate the battery cell (10) with microwaves in order to vibrate and heat the gas (G) inside the battery cell (10) after the activation process, and a degassing section (300) provided to pierce the gas pocket (39) of the battery cell (10) after microwave irradiation and vacuum-suction the gas (G) through the piercing section (38).

[0061] The degassing pre-processing unit (200) is a device for vibrating and heating the gas (G) and electrolyte (40) inside the battery cell (10). The degassing pre-processing unit (200) can be configured to irradiate with microwaves at a variable frequency.

[0062] As described above, the gas (G) within the battery cell (10) can be divided into pocket gas (G1) collected in the gas pocket (39) and stagnant gas (G2) that remains in the electrode assembly (20). In this specification, the term gas (G) within the battery cell (10) can be used as a concept that includes pocket gas (G1) collected in the gas pocket (39) and stagnant gas (G2) that remains in the electrode assembly (20).

[0063] A variable frequency microwave (VFM) is a microwave whose waveform varies depending on the frequency. The frequency of a VFM can be varied within the frequency range of 2.45 GHz to 7 GHz. Depending on the frequency range, the penetration depth of the VFM into the electrode assembly (20) may differ.

[0064] The degassing pretreatment unit (200) can be configured to irradiate the battery cell (10) with microwaves (VFM) while periodically increasing or decreasing the frequency within a predetermined range. By periodically adjusting the frequency, the vibrational energy supplied to the battery cell (10) can be adjusted, and various types of gases can be pretreated depending on the intensity of the vibrational energy.

[0065] Furthermore, the degassing preprocessing unit (200) can be configured to irradiate microwaves (VFM) with varying irradiation times depending on the frequency range. For example, the irradiation time can be varied according to the frequency, such as 1 minute at 3 GHz and 2 minutes at 5 GHz within the range of 2.45 GHz to 7 GHz. This allows for precise control of the thermal energy and vibrational energy transferred to the gas (G) and / or electrolyte (40) within the battery cell (10).

[0066] Alternatively, the degassing preprocessing unit (200) may be configured to irradiate with microwaves (VFM) while maintaining the irradiation time similarly according to the frequency range.

[0067] Furthermore, the degassing preprocessing unit (200) can be configured to irradiate with microwaves (VFM) while increasing the frequency. Alternatively, the degassing preprocessing unit (200) can be configured to irradiate with microwaves (VFM) while decreasing the frequency.

[0068] The degassing preprocessing unit (200) can maintain the temperature of the gas (G) and / or electrolyte (40) in the battery cell (10) at a pre-set temperature (e.g., 60 degrees Celsius) through frequency adjustment. By varying the set temperature according to the type of gas, various types of gases can be preprocessed.

[0069] Referring to Figure 5, the degassing preprocessing unit (200) includes a chamber section (210) provided with a chamber space (211) in which a battery cell (10) is housed, and a microwave irradiation section (230) positioned in the chamber space (211) for irradiating variable microwaves (VFM).

[0070] The chamber portion (210) has a chamber space (211) capable of accommodating a tray (220) containing battery cells (10). One or more battery cells (10) after the activation process are stored in the tray (220). The chamber space (211) may be a sealed space. A microwave irradiation unit (230) can be installed in the chamber space (211). The microwave irradiation unit (230) can generate variable frequency microwaves (VFM) in the chamber space (211).

[0071] Furthermore, the degassing preprocessing unit (200) may include a preprocessing control unit (250) that controls the operating power and operating time of the microwave irradiation unit (230) so that the gas (G) in the battery cell (10) is heated to a predetermined temperature.

[0072] The preprocessing control unit (250) can control the operating power and operating time of the microwave irradiation unit (230) so that the gas (G) in the battery cell (10) is not heated to 60 degrees or higher. The operating power of the microwave irradiation unit (230) may be in the range of 0.1 to 0.3 times the maximum power.

[0073] The aforementioned variable frequency microwaves (VFM) generate heat through the interaction of gas molecules. This heat causes the gas (G) to expand and undergo molecular motion while its pressure increases.

[0074] The gas (G) in the gas pocket (39) is vibrated and heated by variable frequency microwaves (VFM), and its molecular motion becomes active.

[0075] Referring to Figures 6 and 7, the variable frequency microwave (VFM) penetrates the negative electrode (21) and positive electrode (23) of the electrode assembly (20), which are made of metal. The VFM then reacts with the gas (2) and electrolyte, causing the gas (G) and electrolyte (40, see Figure 2) to vibrate and heat.

[0076] The gas (G) stagnating in the electrode assembly (20) is vibrated and heated by variable frequency microwaves (VFM), which activates its molecular motion and allows it to flow from the stagnant region (27) of the electrode assembly (20) into the internal space of the battery cell (10).

[0077] Furthermore, the gas (G) contained in the electrolyte (40) can be vaporized by variable frequency microwaves (VFM) and removed from the electrolyte (40). The gas (G) vaporized from the electrolyte (40) can flow into the internal space of the battery cell (10).

[0078] Figure 8 is a diagram illustrating the process of degassing a battery cell (10a) that has undergone degassing pretreatment according to one embodiment of the present invention.

[0079] The degassing unit (300) is provided to pierce the gas pocket (39) of the degassing pre-treated battery cell (10a) and to vacuum-suction gas (G) through the piercing portion (38). The degassing unit (300) can be installed in the chamber space (211) of the degassing pre-treatment unit (200). Alternatively, the degassing unit (300) can be installed outside the degassing pre-treatment unit (200) and separately from the degassing pre-treatment unit (200).

[0080] In the degassing unit (300), a degassing step is performed to remove the gas (G) inside the battery cell (10a) that has been degassed.

[0081] Referring to Figure 4, the degassing section (300) includes a piercing section (310), an intake section (320), and a sealing section (330). The piercing section (310) is provided to pierce the gas pocket (39) of the battery cell (10). The piercing section (310) can be provided to penetrate the pouch (30) in the region constituting the gas pocket (39) of the battery cell (10). The piercing section (310) forms a piercing area (38) in the region of the pouch (30) constituting the gas pocket (39).

[0082] The suction portion (320) is fluidly connected to the piercing portion (38) of the gas pocket (39) and is provided to apply vacuum pressure to the piercing portion (38). The suction portion (320) can use the piercing portion (38) as a gas discharge passage and draw in gas (G) from within the battery cell (10). The sealing portion (330) is provided to seal the piercing portion (38).

[0083] Conventionally, a degassing step was performed to remove the gas (G) from the battery cell (10) while the battery cell (10) was aging, in a state where the molecular motion of the gas (G) was sluggish. As a result, even after the degassing step, the stagnant gas (G2) that remained in the electrode assembly (20) persisted in the internal space of the battery cell (10) (see Figure 3).

[0084] In contrast, the present invention involves vibrating and heating the gas (G) inside the battery cell (10) to induce molecular motion of the gas (G) before the degassing step, and then performing the degassing step. As shown in Figure 8, the degassing unit (300) can remove not only the pocket gas (G1) collected in the gas pocket (39) but also the stagnant gas (G2) that has accumulated in the electrode assembly (20).

[0085] Furthermore, the degassing device (100) may include a gas measuring unit (400) for measuring the amount of gas in the battery cell (10).

[0086] Table 1 below shows the amount of remaining gas in the battery cell (10) after degassing, with and without the application of variable frequency microwave (VFM) and under variable frequency microwave (VFM) conditions.

[0087] [Table 1]

[0088] In Table 1, the comparative example shows that after degassing of battery cells (10) that have not undergone variable frequency microwave (VFM) treatment, the average residual gas volume of the battery cells (10) (a total of 6 battery cells) was measured. In the comparative example, the average residual gas volume of the battery cells (10) was 14.6 ml.

[0089] Experimental Examples 1 and 2 show the results obtained by varying the operating time while applying the same variable frequency microwave (VFM) conditions and operating power in the range of 2.45 GHz to 7 GHz.

[0090] Experimental Example 1 involved supplying a variable frequency microwave (VFM) to a battery cell (10) at 10% power (operating power, 0.1 times the maximum power) for 10 seconds (operating time), followed by a degassing step for the battery cell (10), and then measuring the average remaining gas amount in the battery cell (10a) (a total of 6 battery cells).

[0091] In Experimental Example 1, the average residual gas volume in battery cell (10a) was 13.8 ml. Even when variable frequency microwave (VFM) was supplied for a very short period of 10 seconds, it was found that the residual gas volume was reduced by approximately 5% compared to a battery cell to which variable frequency microwave (VFM) was not applied (comparative example).

[0092] Experimental Example 2 involves supplying a variable frequency microwave (VFM) at 10% power for 10 minutes, then performing a degassing step on the battery cells (10), and finally measuring the average remaining gas amount in the battery cells (10a) (a total of 6 battery cells).

[0093] In Experimental Example 2, the average residual gas volume in battery cell (10) was 12.6 ml.

[0094] It can be seen that the amount of residual gas in a battery cell treated with variable frequency microwaves (VFM) for 10 minutes (Experimental Example 2) is reduced by approximately 15.8% compared to a battery cell not treated with variable frequency microwaves (VFM) (Comparative Example).

[0095] Furthermore, it was found that the amount of residual gas in a battery cell treated with variable frequency microwaves (VFM) for 10 minutes (Experimental Example 2) was reduced by approximately 9.5% compared to a battery cell treated with variable frequency microwaves (VFM) for 10 seconds (Experimental Example 1). This indicates that even when providing variable frequency microwaves (VFM) to a battery cell (10) with the same power, the longer the operating time of the variable frequency microwaves (VFM), the greater the reduction in the amount of residual gas in the battery cell (10).

[0096] By performing a pre-degassing treatment step before the degassing step, in which the gas (G) inside the battery cell (10) is vibrated and heated, the gas (G) removal efficiency during the degassing step can be improved, and the amount of residual gas in the battery cell (10) can be reduced.

[0097] Furthermore, by reducing the amount of residual gas in the battery cell (10), the performance of the battery cell (10) can be improved and the lifespan of the battery cell (10) can be extended.

[0098] The preferred embodiments of the present invention described above are disclosed for illustrative purposes only, and a person skilled in the art with ordinary skill in the invention will know that various modifications, changes, and additions are possible within the spirit and scope of the invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims. [Industrial applicability]

[0099] According to a degassing apparatus and degassing method relating to one embodiment of the present invention, by heating and vibrating the gas and electrolyte in the battery cell through variable frequency microwaves, it is possible to remove gases that have escaped from the electrode assembly and electrolyte along with gases that have been collected in the gas pockets.

Claims

1. This is a degassing apparatus for degassing the gas inside a battery cell after an activation process of the battery cell, including the electrode assembly. A degassing pre-processing unit is provided to irradiate the battery cell with microwaves in order to vibrate and heat the gas inside the battery cell; and A degassing apparatus including a degassing section provided to pierce the gas pocket of the battery cell after irradiation with microwaves and to vacuum-suction the gas through the pierced portion.

2. The degassing apparatus according to claim 1, wherein the degassing preprocessing unit is provided to irradiate microwaves with a variable frequency within a predetermined range.

3. The degassing apparatus according to claim 2, wherein the frequency is variable in the range of 2.45 GHz to 7 GHz.

4. The degassing preprocessing unit is provided to irradiate the microwaves with varying irradiation times according to a range of frequencies, as described in claim 2.

5. The degassing preprocessing unit is provided to irradiate the microwaves while maintaining the irradiation time similarly according to the frequency range, as described in claim 2.

6. The degassing apparatus according to claim 2, wherein the degassing preprocessing unit is provided to irradiate the microwaves while increasing the frequency.

7. The degassing apparatus according to claim 2, wherein the degassing preprocessing unit is provided to irradiate the microwaves while reducing the frequency.

8. The degassing apparatus according to claim 2, wherein the degassing preprocessing unit is provided to irradiate the microwaves while periodically increasing or decreasing the frequency within a predetermined range.

9. The degassing preprocessing unit is: A chamber section provided with a chamber space in which the aforementioned battery cells are housed; A microwave irradiation unit arranged in the chamber space for irradiating microwaves at a predetermined frequency; and The degassing apparatus according to claim 1, further comprising a preprocessing control unit that controls the operating power and operating time of the microwave irradiation unit so that the gas in the battery cell is heated to a predetermined temperature.

10. The degassing apparatus according to claim 9, wherein the operating power is in the range of 0.1 to 0.3 times the maximum power.

11. The degassing device according to any one of claims 1 to 10, further comprising a gas measuring unit provided for measuring the amount of gas in the battery cell.

12. The degassing unit is, A piercing portion provided to pierce the aforementioned gas pocket; An intake portion is fluidly connected to the piercing portion, applies vacuum pressure to the piercing portion, uses the piercing portion as a gas discharge passage, and is provided to draw in gas from within the battery cell; and A degassing device according to any one of claims 1 to 10, comprising a sealing portion provided for sealing the piercing portion.

13. This is a degassing method for degassing gases within a battery cell after an activation process of the battery cell, including an electrode assembly. A degassing pretreatment step of irradiating the battery cell with microwaves in order to vibrate and heat the gas inside the battery cell; and A degassing method comprising a degassing step of piercing the gas pocket of the battery cell after irradiation with microwaves, and removing the gas from inside the battery cell by vacuum sucking the gas through the pierced area.

14. In the degassing pretreatment step, the microwaves vibrate and heat the stagnant gas that has accumulated in the electrode assembly. The degassing method according to claim 13, wherein the stagnant gas flows from the stagnant region of the electrode assembly into the internal space of the battery cell.

15. In the degassing pretreatment step, the microwave vibrates and heats the electrolyte in the battery cell. The degassing method according to claim 13, wherein the gas contained in the electrolyte vaporizes from the electrolyte and flows from the electrolyte into the internal space of the battery cell.

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