Degassing apparatus and degassing method

Abstract

A degassing apparatus according to an embodiment of the present invention is an apparatus for degassing gas within a battery cell including an electrode assembly after an activation process of the battery cell, and may comprise: a degassing pretreatment unit provided to irradiate the battery cell with microwaves in order to vibrate and heat gas within the battery cell; and a degassing unit provided to, after the microwave irradiation, pierce a gas pocket of the battery cell and vacuum-suction the gas through the pierced portion.

Description

Degassing device and degassing method

[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 within a battery cell after a degassing pretreatment that induces molecular movement of gas within a battery cell.

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0131630, filed October 4, 2023, the entire contents of which are incorporated herein by reference.

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

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

[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 stacking 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 are stacked so as to be in contact with both sides of the separator (22).

[0006] In the assembly step of the battery cell (10), the electrode assembly (20) is housed in a pouch (30). Thereafter, the electrolyte (40) is injected into the cup portion of the pouch (30). Next, the edge portion of the pouch (30) is sealed so that the electrode assembly (20) and the electrolyte (40) are sealed in the cup portion.

[0007] Figure 2 is a drawing for explaining the flow of gas flowing through the excited space of the electrode assembly in the activation process.

[0008] In the above activation process, the battery cell (10) is activated by repeating charging, aging, and discharging several times. Activation of the battery cell (10) is intended to stabilize the battery structure and make it usable.

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

[0010] When a battery cell (10) is activated, a large amount of gas (G) is generated in the internal space of the battery cell (10). As illustrated in Fig. 3, this gas (G) increases the pressure in the internal space of the battery cell (10) and expands the volume of the battery cell (10).

[0011] Referring to the enlarged view of Fig. 2, when the battery cell (10) expands due to internal pressure caused by gas (G), the negative electrode (21) and the separator (22), or the separator (22) and the positive electrode (23), which are in contact with each other, may be excited. In the activation process, the gas (G) within the battery cell (10) may flow through the excited space (24) within the electrode assembly (20).

[0012] The battery cell (10) is aged after the activation process, and at this time, the gas (G) introduced into the electrode assembly (20) may stagnate in the excited space (24) as the molecular movement becomes dull.

[0013] Figure 3 is a drawing for explaining the distribution of gas (G) within a battery cell (10) after the activation process of the battery cell (10).

[0014] Referring to FIG. 3, the gas (G) within the battery cell (10) can be divided into pocket gas (G1) captured in the gas pocket (39) and stagnant gas (G2) stagnant in the electrode assembly (20).

[0015] The battery cell (10) is degassed after aging. The degassing step is to remove gas (G) within the battery cell (10).

[0016] In the degassing step, the pocket gas (G1) can be easily removed by the vacuum pressure provided into the battery cell (10).

[0017] However, the cathode (21), separator (22), and anode (23) of the electrode assembly (20) act as obstacles that impede the flow of vacuum pressure, so that stagnant gas (G2) may remain in the battery cell (10) even after the degassing step.

[0018] In addition, referring to FIG. 2, during the activation process, gas (G) that has penetrated into the electrolyte (40) is also difficult to be absorbed by the vacuum pressure of the degassing step, and may remain in the battery cell.

[0019] Residual gases within these battery cells affect their performance and lifespan. The greater the amount of residual gas within a battery cell, the lower its performance and shorter its lifespan.

[0020] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a degassing device and a degassing method capable of reducing the amount of gas remaining in a battery cell after degassing by performing a degassing process for removing gas from a battery cell after degassing pretreatment that induces molecular movement of gas within the battery cell.

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

[0022] The above degassing pretreatment unit may be configured to irradiate microwaves at variable frequencies.

[0023] In one embodiment, the degassing pretreatment unit may be configured to irradiate microwaves at a variable frequency within a predetermined range.

[0024] Additionally, the frequency can be varied in the range of 2.45 GHz to 7 GHz.

[0025] In addition, the degassing pretreatment unit may be arranged to irradiate the microwaves by varying the irradiation time according to the frequency range.

[0026] Additionally, the degassing pretreatment unit may be arranged to irradiate the microwave while maintaining the irradiation time the same according to the frequency range.

[0027] Additionally, the degassing preprocessing unit may be configured to irradiate the microwave while increasing the frequency. The degassing preprocessing unit may be configured to irradiate the microwave while increasing the frequency within a predetermined range (e.g., a range of 2.45 GHz to 7 GHz).

[0028] Additionally, the degassing preprocessing unit may be configured to irradiate the microwave while reducing the frequency. The degassing preprocessing unit may be configured to irradiate the microwave while reducing the frequency within a predetermined range (e.g., a range of 2.45 GHz to 7 GHz).

[0029] Additionally, the degassing preprocessing unit may be arranged to irradiate the microwave while periodically increasing or decreasing the frequency within a predetermined range.

[0030] In addition, the degassing preprocessing unit may include a chamber unit having a chamber space in which the battery cell is accommodated, a microwave irradiation unit disposed in the chamber space and irradiating microwaves at a predetermined frequency, and a preprocessing control unit that controls the operating power and operating time of the microwave irradiation unit so that the gas within the battery cell is heated to a preset temperature.

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

[0032] Additionally, the degassing device may include a gas measuring unit configured to measure the amount of gas within the battery cell.

[0033] In addition, the degassing unit may include a piercing unit configured to pierce the gas pocket, a suction unit configured to be fluidly connected to the piercing portion, apply vacuum pressure to the piercing portion, and suck gas within the battery cell using the piercing portion as a gas discharge passage, and a sealing unit configured to seal the piercing portion.

[0034] In addition, a degassing method according to one embodiment of the present invention is a method using the degassing device, wherein the degassing method is for degassing gas within a battery cell after an activation process of a battery cell including an electrode assembly, and may include a degassing pretreatment step of irradiating microwaves to the battery cell to vibrate and heat the gas within the battery cell, and a degassing step of piercing a gas pocket of the battery cell after the irradiation of microwaves and vacuum-sucking the gas through the piercing portion to remove the gas within the battery cell.

[0035] In the above degassing pretreatment step, the microwave vibrates and heats the stagnant gas stagnant in the electrode assembly, and the stagnant gas can flow from the stagnant region of the electrode assembly into the internal space of the battery cell.

[0036] Additionally, in the degassing pretreatment step, the microwave vibrates and heats the electrolyte in the battery cell, and the gas contained in the electrolyte is vaporized in the electrolyte and can flow from the electrolyte into the internal space of the battery cell.

[0037] In one embodiment, in the degassing pretreatment step, it may be arranged to irradiate microwaves with a frequency varying within a predetermined range.

[0038] Additionally, in the degassing preprocessing step, the frequency can be varied in the range of 2.45 GHz to 7 GHz.

[0039] Additionally, in the degassing pretreatment step, the microwaves may be irradiated at different irradiation times depending on the frequency range.

[0040] Additionally, in the above degassing pretreatment step, it may be arranged to irradiate the microwave while maintaining the irradiation time the same according to the frequency range.

[0041] Additionally, in the degassing preprocessing step, the microwaves may be irradiated while increasing the frequency. The degassing preprocessing unit may be irradiated while increasing the frequency within a predetermined range (e.g., a range of 2.45 GHz to 7 GHz).

[0042] Additionally, in the degassing preprocessing step, the microwaves may be irradiated while reducing the frequency. The degassing preprocessing unit may be irradiated while reducing the frequency within a predetermined range (e.g., a range of 2.45 GHz to 7 GHz).

[0043] Additionally, in the degassing pretreatment step, it may be arranged to irradiate the microwave while periodically increasing or decreasing the frequency within a predetermined range.

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

[0045] Through a degassing pretreatment process for a battery cell, a degassing process is performed by heating and vibrating the gas and electrolyte inside the battery cell using variable frequency microwaves, thereby removing the gas trapped in the gas pockets as well as the gas that escaped from the electrode assembly and electrolyte.

[0046] By performing degassing after the degassing pretreatment for the above battery cell, gas trapped in a gas pocket, gas stagnant in an electrode assembly after activation, and gas absorbed into an electrolyte during activation can be removed, thereby improving gas removal efficiency and reducing the amount of gas remaining in the battery cell after degassing.

[0047] In addition, the amount of residual gas in a battery cell can be reduced by approximately 10% to 15% compared to the amount of residual gas in a conventional battery cell that has not undergone degassing pretreatment.

[0048] Additionally, by reducing the amount of residual gas in the battery cell, the performance of the battery cell can be improved and the life of the battery cell can be extended.

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

[0050] Figure 2 is a drawing for explaining the flow of gas flowing through the excitation space of the electrode assembly in the activation process.

[0051] Figure 3 is a drawing for explaining the gas distribution within a battery cell after the activation process of the battery cell.

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

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

[0054] FIG. 6 is a drawing for explaining the molecular movement of gas in a degassing pre-treated battery cell according to one embodiment of the present invention.

[0055] Figure 7 is a drawing for explaining the flow of stagnant gas in the stagnation area of ​​Figure 6 during degassing pretreatment.

[0056] FIG. 8 is a drawing for explaining a process of degassing a battery cell that has been degassed according to one embodiment of the present invention.

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

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

[0059] FIG. 6 is a drawing for explaining the molecular movement of gas in a battery cell (10a) that has undergone degassing pretreatment in one embodiment of the present invention, and FIG. 7 is a drawing for explaining the flow of stagnant gas in the stagnation area of ​​FIG. 6 during degassing pretreatment.

[0060] Referring to FIGS. 2, 3, 4 and 5, a degassing device (100) according to one embodiment of the present invention is a device 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 pretreatment unit (200) configured to irradiate microwaves to the battery cell (10) to vibrate and heat the gas (G) inside the battery cell (10) after the activation process, and a degassing unit (300) configured to pierce a gas pocket (39) of the battery cell (10) after the irradiation of microwaves and vacuum-suck the gas (G) through the piercing portion (38).

[0061] The above degassing pretreatment unit (200) is a device for vibrating and heating the gas (G) and electrolyte (40) within the battery cell (10). The degassing pretreatment unit (200) may be configured to irradiate microwaves at a variable frequency.

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

[0063] Variable frequency microwaves (VFM) are microwaves whose waveform varies depending on their frequency. Variable frequency microwaves (VFM) can vary their frequency within a frequency range of 2.45 GHz to 7 GHz. Depending on the frequency range, the penetration depth of VFM into an electrode assembly (20) can vary.

[0064] The above-described degassing preprocessing unit (200) may be configured to irradiate microwaves (VFM) while periodically increasing or decreasing the frequency within a predetermined range. By periodically adjusting the frequency, the vibration energy provided to the battery cell (10) can be controlled, thereby enabling preprocessing of various types of gases depending on the intensity of the vibration energy.

[0065] In addition, the degassing preprocessing unit (200) may be configured to irradiate microwaves (VFM) at different irradiation times depending on the frequency range. For example, in the range of 2.45 GHz to 7 GHz, the irradiation time may be varied depending on the frequency, such as 1 minute for 3 GHz, 2 minutes for 5 GHz, etc. Through this, the thermal energy and vibrational energy transferred to the gas (G) and / or electrolyte (40) within the battery cell (10) can be precisely controlled.

[0066] Alternatively, the degassing pretreatment unit (200) may be arranged to irradiate microwaves (VFM) while maintaining the irradiation time the same according to the frequency range.

[0067] Additionally, the degassing pretreatment unit (200) may be configured to irradiate microwaves (VFM) while increasing the frequency. Alternatively, the degassing pretreatment unit (200) may be configured to irradiate microwaves (VFM) while decreasing the frequency.

[0068] The above degassing preprocessing unit (200) can maintain the temperature of the gas (G) and / or electrolyte (40) within the battery cell (10) at a preset temperature (e.g., 60 degrees) through frequency adjustment. By varying the preset temperature depending on the type of gas, various types of gases can be preprocessed.

[0069] Referring to FIG. 5, the degassing pretreatment unit (200) includes a chamber unit (210) in which a chamber space (211) is provided to accommodate a battery cell (10), and a microwave irradiation unit (230) disposed in the chamber space (211) and for irradiating variable microwaves (VFM).

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

[0071] In addition, 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) within the battery cell (10) is heated to a preset temperature.

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

[0073] The above variable frequency microwaves (VFM) generate heat through the interaction of gas molecules. This heat causes the gas (G) to expand and its pressure to increase, leading to molecular motion.

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

[0075] Referring to FIGS. 6 and 7, variable frequency microwaves (VFM) penetrate the cathode (21) and the anode (23) of the electrode assembly (20) made of metal. In addition, the variable frequency microwaves (VFM) react with the gas (2) and the electrolyte, thereby vibrating and heating the gas (G) and the electrolyte (40, see FIG. 2).

[0076] The gas (G) stagnant in the electrode assembly (20) is vibrated and heated by variable frequency microwaves (VFM), and as the molecular motion becomes active, it can flow from the stagnant region (27) of the electrode assembly (20) into the internal space of the battery cell (10).

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

[0078] FIG. 8 is a drawing for explaining a process of degassing a battery cell (10a) that has been degassed according to one embodiment of the present invention.

[0079] The above degassing unit (300) is provided to pierce the gas pocket (39) of the battery cell (10a) that has been subjected to degassing pretreatment and to vacuum-suck the gas (G) through the piercing portion (38). The degassing unit (300) may be installed in the chamber space (211) of the degassing pretreatment unit (200). Alternatively, the degassing unit (300) may be installed outside the degassing pretreatment unit (200), separately from the degassing pretreatment unit (200).

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

[0081] Referring to FIG. 4, the degassing portion (300) includes a piercing portion (310), a suction portion (320), and a sealing portion (330). The piercing portion (310) is provided to pierce a gas pocket (39) of a battery cell (10). The piercing portion (310) may be provided to penetrate a pouch (30) in an area forming the gas pocket (39) of the battery cell (10). By the piercing portion (310), a piercing portion (38) is formed in an area of ​​the pouch (30) forming the gas pocket (39).

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

[0083] In the past, as the battery cell (10) went through an aging process, a degassing step was performed to remove gas (G) from the battery cell (10) in a state where the molecular movement of gas (G) was insensitive. Therefore, even after the degassing step, the stagnant gas (G2) that had stagnated in the electrode assembly (20) remained in the internal space of the battery cell (10) (see FIG. 3).

[0084] In contrast, the present invention performs the degassing step by vibrating and heating the gas (G) inside the battery cell (10) before the degassing step to induce molecular movement of the gas (G). Accordingly, as illustrated in FIG. 8, the degassing unit (300) can remove not only the pocket gas (G1) trapped in the gas pocket (39), but also the stagnant gas (G2) stagnant in the electrode assembly (20).

[0085] Additionally, the degassing device (100) may include a gas measuring unit (400) that measures the amount of gas within the battery cell (10).

[0086] [Table 1] below shows the amount of residual gas in a battery cell (10) after degassing depending on whether variable frequency microwave (VFM) is applied and the variable frequency microwave (VFM) conditions.

[0087] VFM application VFM condition (time) Quantity (cell) Average remaining gas amount (ml) Comparison example Not applied -614.6 Experimental example 1 applied 10 sec 613.8 Experimental example 2 applied 10 min 612.6

[0088] In Table 1, the comparative example is the average residual gas amount of the battery cell (10) (a total of 6 battery cells) measured after performing the degassing step on the battery cell (10) that was not subjected to variable frequency microwave (VFM) treatment. In the comparative example, the average residual gas amount of the battery cell (10) is 14.6 ml.

[0089] Experimental examples 1 and 2 are the results of applying the same variable frequency microwave (VFM) conditions in the range of 2.45 GHz to 7 GHz, applying the same operating power, and varying the operating time.

[0090] Experimental Example 1 is a case where a variable frequency microwave (VFM) is provided to a battery cell (10) for 10 seconds (operating time) at 10% of the power (operating power, 0.1 times the maximum power), and then a degassing step is performed on the battery cell (10), and then the average remaining gas amount of the battery cell (10a) (a total of 6 battery cells) is measured.

[0091] In Experimental Example 1, the average residual gas amount of the battery cell (10a) is 13.8 ml. Even when variable frequency microwaves (VFM) are applied for a very short period of 10 seconds, it can be seen that the residual gas amount is reduced by approximately 5% compared to a battery cell (comparative example) to which variable frequency microwaves (VFM) are not applied.

[0092] Experimental Example 2 is a test in which variable frequency microwaves (VFM) were applied to a battery cell (10) for 10 minutes at 10% power, a degassing step was performed on the battery cell (10), and then the average residual gas amount of the battery cell (10a) (a total of 6 battery cells) was measured.

[0093] In Experimental Example 2, the average remaining gas volume of the battery cell (10) is 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 to which variable frequency microwaves (VFM) are not applied (Comparative Example).

[0095] In addition, it can be seen that the battery cell treated with variable frequency microwaves (VFM) for 10 minutes (Experimental Example 2) has approximately 9.5% less residual gas than the battery cell treated with variable frequency microwaves (VFM) for 10 seconds (Experimental Example 1). This shows that even when variable frequency microwaves (VFM) are provided to the battery cell (10) at the same power, the longer the operating time of the variable frequency microwaves (VFM), the more the residual gas of the battery cell (10) is reduced.

[0096] By performing a degassing pretreatment step of vibrating and heating the gas (G) inside the battery cell (10) before the degassing step, the gas (G) removal efficiency of the degassing step can be improved and the amount of residual gas in the battery cell (10) can be reduced.

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

[0098] The preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and those skilled in the art having ordinary knowledge of the present invention will be able to make various modifications, changes, and additions within the spirit and scope of the present invention, and such modifications, changes, and additions should be considered to fall within the scope of the following claims.

[0099] According to a degassing device and a degassing method using the same related to one embodiment of the present invention, by heating and vibrating gas and electrolyte inside a battery cell using variable frequency microwaves, gas trapped in a gas pocket as well as gas escaping from an electrode assembly and electrolyte can be removed.

Claims

1. A degassing device for degassing gas inside a battery cell after an activation process of the battery cell including an electrode assembly, A degassing pretreatment unit configured to irradiate microwaves to the battery cell to vibrate and heat the gas within the battery cell; and A degassing device including a degassing unit configured to pierce a gas pocket of the battery cell after the microwave irradiation and to vacuum-suck the gas through the piercing portion.

2. In paragraph 1, The above degassing pretreatment unit is a degassing device configured to irradiate microwaves by varying the frequency within a predetermined range.

3. In paragraph 2, A degassing device having a variable frequency in the range of 2.45 GHz to 7 GHz.

4. In paragraph 2, The above degassing pretreatment unit is a degassing device that is arranged to irradiate the microwaves by varying the irradiation time according to the frequency range.

5. In paragraph 2, The above degassing pretreatment unit is a degassing device that is arranged to irradiate the microwave while maintaining the irradiation time the same according to the frequency range.

6. In paragraph 2, The above degassing pretreatment unit is a degassing device arranged to irradiate the microwave while increasing the frequency.

7. In paragraph 2, The above degassing pretreatment unit is a degassing device configured to irradiate the microwave while reducing the frequency.

8. In paragraph 2, The above degassing pretreatment unit is a degassing device configured to irradiate the microwave while periodically increasing or decreasing the frequency within a predetermined range.

9. In the first paragraph, the degassing pretreatment unit, A chamber section having a chamber space for accommodating the above battery cell; A microwave irradiation unit disposed in the chamber space and for irradiating microwaves at a predetermined frequency; and A degassing device including a pretreatment control unit that controls the operating power and operating time of the microwave irradiation unit so that the gas within the battery cell is heated to a preset temperature.

10. In paragraph 9, A degassing device having an operating power in the range of 0.1 to 0.3 times the maximum power.

11. In paragraph 1, A degassing device further comprising a gas measuring unit configured to measure the amount of gas within the battery cell.

12. In the first paragraph, the degassing part A piercing portion provided to pierce the above gas pocket; A suction unit that is fluidly connected to the piercing portion, applies vacuum pressure to the piercing portion, and is provided to suck gas within the battery cell using the piercing portion as a gas discharge passage; and A degassing device including a sealing portion provided to seal the above piercing site.

13. A degassing method for degassing gas 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 to vibrate and heat the gas within the battery cell; and A degassing method comprising a degassing step of piercing a gas pocket of the battery cell after the microwave irradiation and vacuum-sucking the gas through the piercing portion to remove the gas within the battery cell.

14. In paragraph 13, In the above degassing pretreatment step, the microwave vibrates and heats the stagnant gas stagnant in the electrode assembly, A degassing method in which the stagnant gas flows from the stagnant region of the electrode assembly into the internal space of the battery cell.

15. In paragraph 13, In the above degassing pretreatment step, the microwave vibrates and heats the electrolyte in the battery cell, A degassing method in which a gas contained in the electrolyte is vaporized in the electrolyte and flows from the electrolyte into the internal space of the battery cell.

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