Liquid injection device and liquid injection method

Abstract

The present application relates to the technical field of battery manufacturing, and in particular to a liquid injection device and a liquid injection method. The liquid injection device includes a vacuum assembly and a gas injection assembly; the vacuum assembly has a vacuum end for communicating with the gas inside the shell to extract the gas inside the shell; the gas injection assembly has an air inlet end and a gas injection end, the air inlet end is connected to a gas storage container, and the gas injection end is used to communicate with the gas inside the shell to inject the target gas in the gas storage container into the shell; the target gas in the gas storage container is a gas soluble in an electrolyte. The liquid injection device and liquid injection method provided in the embodiments of the present application can improve the liquid injection efficiency of battery cells.

Description

Technical Field

[0001] The present application relates to the technical field of battery manufacturing, and in particular to a liquid injection device and a liquid injection method. Background Art

[0002] A battery cell generally includes a shell, an electrode assembly disposed in the shell, and an electrolyte contained in the shell for soaking the electrode assembly. In the process of manufacturing lithium batteries, the electrolyte in the injection container needs to be injected into the shell. As the energy density of lithium batteries increases, the density of the electrode assembly becomes larger and larger, and it becomes more difficult for the electrolyte to completely soak the electrode assembly, resulting in a slow flow of the electrolyte into the shell and reduced injection efficiency.

[0003] In order to improve the injection efficiency, the prior art extracts the air in the shell before injection to speed up the flow of electrolyte into the shell. However, the injection efficiency cannot be significantly improved due to incomplete extraction of the air in the shell. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide a liquid injection device and a liquid injection method, which can improve the liquid injection efficiency.

[0005] According to one aspect of an embodiment of the present application, a liquid injection device is provided for injecting electrolyte into the shell of a battery cell, the liquid injection device comprising: a vacuum assembly and a gas injection assembly; the vacuum assembly has a vacuum end for communicating with the gas inside the shell to extract the gas inside the shell; the gas injection assembly has an air inlet end and a gas injection end, the air inlet end is connected to a gas storage container, and the gas injection end is for communicating with the gas inside the shell to inject the target gas in the gas storage container into the shell; the target gas in the gas storage container is a gas soluble in the electrolyte.

[0006] By adopting the above scheme, before injecting electrolyte into the shell, the target gas is introduced into the shell by using the gas injection component, the air in the shell is replaced by the target gas, and then the gas in the shell is extracted by using the exhaust component, and finally the electrolyte is injected into the shell. During the injection process, even if there is residual target gas in the shell, since the target gas is soluble in the electrolyte, the residual gas has less resistance to the electrolyte injection process, thereby improving the injection efficiency.

[0007] In some embodiments, the solubility of the target gas in the gas storage container in the electrolyte is greater than 0.1.

[0008] By adopting the above scheme, the solubility of the target gas in the electrolyte is relatively large, and the resistance to the process of injecting the electrolyte into the shell and wetting the electrode assembly is relatively small, thereby improving the injection efficiency of the electrolyte and preventing incomplete wetting of the electrode assembly by the electrolyte and affecting the charge and discharge performance of the battery cell.

[0009] In some embodiments, the target gas in the gas storage container is dry CO2 or CO gas.

[0010] By adopting the above scheme, CO2 or CO is a gas that is easy to produce and low in cost and can be dissolved in the electrolyte, which can reduce the cost of injection. In addition, after the dry gas is introduced into the shell, it will not affect the concentration ratio of the electrolyte, thereby ensuring the electrochemical performance of the battery cell after injection.

[0011] In some embodiments, the gas injection assembly further includes: a pressure regulating valve, which is disposed between the gas inlet end and the gas injection end and is used to control the outflow speed of the gas flow at the gas injection end.

[0012] By adopting the above solution, the pressure regulating valve adjusts the air flow velocity at the gas injection end, thereby controlling the speed at which the gas flows into the shell, thereby achieving the effect of controlling the air pressure in the shell.

[0013] According to another aspect of an embodiment of the present application, a liquid injection method is provided, comprising:

[0014] A target gas is injected into the housing of the battery cell, where the target gas is a gas soluble in the electrolyte.

[0015] Extract gas from the housing of the battery cell.

[0016] The electrolyte is injected into the housing of the battery cell.

[0017] By adopting the above scheme, the target gas is injected into the shell, the air in the shell is replaced by the target gas, and then the target gas in the shell is extracted. After the gas in the shell is extracted, even if there is residual target gas in the shell, since the target gas can be dissolved in the electrolyte, the residual target gas has less resistance to the electrolyte injection process, thereby improving the injection efficiency.

[0018] In some embodiments, it is necessary to extract the gas in the housing of the battery cell before and after injecting the target gas into the housing of the battery cell.

[0019] By adopting the above scheme, before injecting the target gas, the extracted gas is the air in the shell, and after the air is extracted, a negative pressure is formed in the shell, which is convenient for the injection of the target gas; after the target gas is injected, the target gas is the main gas in the shell, and after the target gas is extracted, a negative pressure is formed in the shell, which is convenient for the injection of the electrolyte.

[0020] In some embodiments, during the process of injecting electrolyte into the shell of the battery cell, the air pressure in the shell is controlled to be lower than the air pressure in the injection container to speed up the flow of electrolyte in the injection container into the shell.

[0021] By adopting the above solution, since the air pressure in the shell is lower than the air pressure in the liquid injection container, the electrolyte in the liquid injection container is accelerated to flow toward the shell under the impetus of the air pressure in the liquid injection container, thereby improving the liquid injection efficiency.

[0022] In some embodiments, injecting electrolyte into the housing of the battery cell includes: injecting gas into a liquid injection container to control the gas pressure in the housing of the battery cell to be lower than the gas pressure in the liquid injection container.

[0023] By adopting the above scheme, injecting gas into the liquid injection container can increase the air pressure in the liquid injection container, so that the air pressure in the shell is lower than the air pressure in the liquid injection container. As the injection of electrolyte progresses, the speed of injecting gas into the liquid injection container can be flexibly adjusted, so as to adjust the air pressure difference between the liquid injection container and the shell in real time. The implementation of this air pressure control method is relatively simple, and the implementation method is flexible and controllable.

[0024] In some embodiments, before injecting the electrolyte into the shell, the injection method further includes: drying the electrode assembly of the battery cell.

[0025] By adopting the above solution, the electrode assembly may absorb moisture from the surrounding environment during the manufacturing process, and this part of moisture is mixed into the electrolyte, which may affect the ratio of the electrolyte. Drying the electrode assembly before injection can reduce the moisture in the electrode assembly, thereby reducing the impact of moisture on the electrolyte ratio, making the electrochemical performance of the battery cell stable.

[0026] In some embodiments, drying the electrode assembly of the battery cell further comprises: extracting gas in the oven and injecting the target gas into the oven.

[0027] By adopting the above scheme, during the process of drying the electrode assembly, the moisture in the electrode assembly evaporates and turns into water vapor. During the process of extracting the gas in the oven, this part of the gas containing water vapor is extracted, and then the target gas is injected into the oven to replace the moist gas in the oven and the shell of the battery cell, thereby preventing this part of the gas containing water vapor from remaining in the shell and affecting the drying effect of the electrode assembly.

[0028] In the embodiment of the present application, before injecting electrolyte into the shell of the battery cell, a target gas is introduced into the shell by using a gas injection assembly, the air in the shell is replaced by the target gas, and then the gas extraction assembly is used to extract the gas in the shell, and finally the electrolyte is injected into the shell. During the injection process, even if there is residual target gas in the shell, since the target gas is soluble in the electrolyte, the residual gas has less resistance to the electrolyte injection process, thereby improving the injection efficiency.

[0029] The above description is only an overview of the technical solution of the embodiment of the present application. In order to more clearly understand the technical means of the embodiment of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 This is a simplified structural diagram of a liquid injection device in one embodiment of the present application.

[0032] Figure 2 This is a simplified diagram of a usage state of a liquid injection device in one embodiment of the present application.

[0033] Figure 3 This is a simplified diagram of another usage state of the liquid injection device in one embodiment of the present application.

[0034] Figure 4 A flow chart of a liquid injection method provided in one embodiment of the present application.

[0035] Figure 5 A flow chart of a liquid injection method provided in another embodiment of the present application.

[0036] Figure 6 This is a simplified structural diagram of using a gas injection assembly to inject gas into a liquid injection container in one embodiment of the present application.

[0037] Figure 7 This is a flow chart of the liquid injection method provided in another embodiment of the present application.

[0038] Figure 8 This is a flow chart of a method for drying an electrode assembly of a battery cell in one embodiment of the present application.

[0039] Explanation of the reference numerals in the accompanying drawings: 1. Vacuum assembly; 11. Vacuum end; 12. Vacuum pump; 13. Vacuum pipe; 14. Vacuum valve; 2. Gas injection assembly; 21. Gas inlet end; 22. Gas injection end; 23. Air supply pump; 24. Air supply pipe; 25. Air supply valve; 26. Pressure regulating valve; 3. Gas storage container; 4. Liquid injection container; 5. Battery cell; 6. Oven. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0042] The terms "comprising" and "having" and any variations thereof in the specification, claims and drawings of this application are intended to cover but not exclude other contents. The word "a" or "an" does not exclude the presence of a plurality.

[0043] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0044] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the injection device of the present application. For example, in the description of the present application, the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present application.

[0045] In the description of the present application, unless otherwise specified, "plurality" means more than two (including two), and similarly, "multiple groups" means more than two groups (including two).

[0046] In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, the "connection" or "connection" of a mechanical structure may refer to a physical connection. For example, the physical connection may be a fixed connection, such as a fixed connection through a fixing member, such as a fixed connection through a screw, bolt or other fixing member; the physical connection may also be a detachable connection, such as a mutual snap connection or snap connection; the physical connection may also be an integral connection, such as welding, bonding or integral molding to form a connection for connection. The "connection" or "connection" of a circuit structure may refer to an electrical connection or a signal connection in addition to a physical connection. For example, it may be a direct connection, that is, a physical connection, or it may be an indirect connection through at least one intermediate element, as long as the circuit is connected, or it may be the internal connection of two elements; the signal connection may refer to a signal connection through a media medium, such as a radio wave, in addition to a signal connection through a circuit. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0047] A battery cell generally includes a shell, an electrode assembly disposed in the shell, and an electrolyte contained in the shell for soaking the electrode assembly. In the process of manufacturing lithium batteries, the electrolyte in the injection container needs to be injected into the shell. As the energy density of lithium batteries increases, the density of the electrode assembly becomes larger and larger, and it becomes more difficult for the electrolyte to completely soak the electrode assembly, resulting in a slow flow of the electrolyte into the shell and reduced injection efficiency.

[0048] In order to improve the injection efficiency, the prior art extracts the air in the shell before injection so that the air pressure in the shell is lower than normal pressure. During the injection process, after the injection container is connected to the injection hole on the shell, the electrolyte can flow into the shell faster under the action of negative pressure because the air pressure in the shell is low.

[0049] However, after adopting the above technical solution, the infiltration speed of the electrolyte can only be improved to a certain extent in the initial stage of electrolyte injection, and then the electrolyte still flows into the shell at a relatively low speed.

[0050] After research, the inventors found that this is because in the early stage of electrolyte injection, the negative pressure in the shell can absorb the electrolyte into the shell, but as the electrolyte continues to be injected, the injection speed of the electrolyte depends more on the infiltration speed of the electrolyte into the electrode assembly. The faster the infiltration speed, the faster the electrolyte flows in, and vice versa. When there is more gas between the tab layers of the electrode assembly, the gas will hinder the infiltration of the electrolyte, causing the infiltration speed of the electrolyte to slow down, and the gas filled between the tab layers of the electrode assembly is difficult to be completely extracted, resulting in the inability to significantly improve the injection efficiency.

[0051] In view of this, an embodiment of the present application provides a liquid injection device and a liquid injection method, which stores a target gas soluble in an electrolyte in a gas storage container, injects the target gas into the shell of the battery cell through a gas injection component to replace the air in the shell, and then uses a vacuum component to extract the gas in the shell. At this time, the gas remaining in the shell is mainly a small amount of target gas. During the liquid injection process, since the target gas can be dissolved in the electrolyte, the target gas has less obstruction to the electrolyte, so that the electrolyte can quickly infiltrate the electrode assembly, thereby accelerating the speed of injecting the electrolyte into the shell.

[0052] like Figure 1 As shown, according to one aspect of an embodiment of the present application, there is provided a liquid injection device for injecting electrolyte into the shell of a battery cell 5, the liquid injection device comprising: a vacuum assembly 1 and a gas injection assembly 2; the vacuum assembly 1 has a vacuum end 11 for communicating with the gas inside the shell to extract the gas inside the shell; the gas injection assembly 2 has an air inlet end 21 and an injection end 22, the air inlet end 21 is connected to a gas storage container 3, and the gas injection end 22 is used to communicate with the gas inside the shell to inject the target gas in the gas storage container 3 into the shell; the target gas in the gas storage container 3 is a gas soluble in the electrolyte.

[0053] The gas extraction component 1 extracts the gas in the shell to make the shell into a negative pressure state. Under the negative pressure state, it is convenient to inject gas or liquid into the shell. The gas extracted by the gas extraction component 1 can be air, target gas, or other mixed gas or pure gas, which is not limited in the embodiment of the present application. In addition, the gas extraction component 1 can be used for gas extraction operations in any link during the liquid injection process. This is used according to actual conditions and does not affect the structure and function of the gas extraction component 1 in the embodiment of the present application.

[0054] In addition, the exhaust component 1 can extract the gas in the shell by directly connecting the exhaust end 11 to the shell of the battery cell 5 to extract the gas in the shell, or the exhaust end 11 of the exhaust component 1 can be connected to other media to extract the gas in the shell.

[0055] For example, Figure 1 As shown, in some embodiments, the vacuum assembly 1 includes a vacuum pump 12, a vacuum pipe 13 and a vacuum valve 14 connected to the vacuum pipe 13. The end of the vacuum pipe 13 away from the vacuum pump 12 is the vacuum end 11. When in use, the vacuum end 11 is connected to the component that needs to be vacuumed, and the vacuum pump 12 and the vacuum valve 14 are opened to extract gas. After the vacuuming is completed, the wall vacuum pump 12 and the vacuum valve 14 can be closed.

[0056] The gas injection component 2 injects the target gas in the gas storage container 3 into the shell, so that the target gas replaces the air in the shell. Since the target gas is soluble in the electrolyte, during the electrolyte injection process, the target gas will not form resistance to the infiltration of the electrolyte, or the resistance to the electrolyte is small, thereby accelerating the infiltration of the electrolyte and improving the injection efficiency.

[0057] Similarly, the way in which the gas injection component 2 injects gas into the shell of the battery cell 5 is that the gas injection end 22 of the gas injection component 2 is directly connected to the battery cell 5 and the target gas is injected into the shell of the battery cell 5, or the gas injection end 22 of the gas injection component 2 is connected to the space where the battery cell 5 is located, and the gas injection component 2 injects the target gas into the space where the battery cell 5 is located, thereby allowing the target gas to flow from the space into the shell of the battery cell 5.

[0058] For example, Figure 1 As shown, in some embodiments, the gas injection assembly 2 includes a gas pump 23, a gas pipeline 24, and a gas valve 25 connected to the gas pipeline 24. One end of the gas pipeline 24 is the gas inlet end 21, and the other end is the gas injection end 22. The gas inlet end 21 is connected to the gas storage container 3. When in use, the gas injection end 22 is connected to the component that needs to be injected with gas, the gas pump 23 and the gas valve 25 are turned on, and the target gas in the gas storage container 3 is sent to the gas injection end 22 along the gas pipeline 24, and injected into the component connected to the gas injection end 22. After the injection of the target gas is completed, the gas pump 23 and the gas valve 25 are closed.

[0059] like Figure 2 As shown, in a possible use state, multiple battery cells 5 are placed in a relatively closed space, such as an oven 6. When the gas in the shell needs to be extracted, the extraction end 11 of the extraction component 1 is connected to the closed space to extract the gas in the closed space, and then the gas in the shells of all battery cells 5 located in the closed space is extracted. Similarly, when the target gas needs to be injected, the injection end 22 of the injection component 2 is connected to the closed space, and the target gas is introduced into the closed space, and then the target gas flows from the closed space into the shell.

[0060] like Figure 3 As shown, in another possible use state, the gas extraction end 11 of the gas extraction assembly 1 is directly connected to the shell of the battery cell 5 to extract the gas in the shell. Similarly, when the target gas needs to be injected, the gas injection end 22 of the liquid injection assembly is directly connected to the shell of the battery cell 5 to inject the target gas into the shell of the battery cell 5.

[0061] In some embodiments, the solubility of the target gas in the gas storage container 3 in the electrolyte is greater than 0.1.

[0062] By adopting the above scheme, the solubility of the target gas in the electrolyte is relatively large, and the resistance to the process of injecting the electrolyte into the shell and wetting the electrode assembly is relatively small, thereby improving the injection efficiency of the electrolyte and preventing incomplete wetting of the electrode assembly by the electrolyte and affecting the charge and discharge performance of the battery cell 5.

[0063] In some embodiments, the target gas in the gas storage container 3 is dry CO 2 or CO gas.

[0064] By adopting the above scheme, CO2 or CO is a gas that is easy to produce and low in cost and can be dissolved in the electrolyte, which can reduce the cost of injection. In addition, after the dry gas is introduced into the shell, it will not affect the concentration ratio of the electrolyte, thereby ensuring the electrochemical performance of the battery cell 5 after injection.

[0065] In some other embodiments, the target gas in the gas storage container 3 is a mixture of dry CO 2 and CO gases.

[0066] like Figure 2 and Figure 3 As shown, in some embodiments, the gas injection assembly 2 further includes a pressure regulating valve 26 , which is disposed between the gas inlet end 21 and the gas injection end 22 and is used to control the outflow speed of the gas flow at the gas injection end 22 .

[0067] By adopting the above solution, the pressure regulating valve 26 adjusts the outflow speed of the gas injection end 22, thereby controlling the speed at which the gas flows into the shell, and further achieving the effect of controlling the air pressure in the shell. When the air flow flows in faster, the air pressure in the shell rises faster, and the air pressure in the shell is higher; when the air flow flows in slower, the air pressure in the shell rises slower, and the air pressure in the shell is lower.

[0068] According to another aspect of an embodiment of the present application, a liquid injection method is provided.

[0069] like Figure 4 As shown, in some embodiments, the injection method includes:

[0070] S10 : Injecting target gas into the casing of the battery cell 5 .

[0071] S11: Extracting the gas in the casing of the battery cell 5 .

[0072] S12: injecting electrolyte into the housing of the battery cell 5 .

[0073] The target gas is a gas soluble in the electrolyte.

[0074] By adopting the above scheme, the target gas is injected into the shell, the air in the shell is replaced by the target gas, and then the target gas in the shell is extracted. After the gas in the shell is extracted, even if there is residual target gas in the shell, since the target gas can be dissolved in the electrolyte, the residual target gas has less resistance to the electrolyte injection process, thereby improving the injection efficiency.

[0075] like Figure 5 As shown, in some embodiments, the gas in the shell of the battery cell 5 needs to be extracted before and after injecting the target gas into the shell, that is, the step of extracting the gas in the shell of the battery cell 5 is performed at least twice, thereby forming the following injection method:

[0076] S20: Extracting the gas in the casing of the battery cell 5.

[0077] S21 : Injecting target gas into the casing of the battery cell 5 .

[0078] S22: Extracting the gas in the casing of the battery cell 5.

[0079] S23 : injecting electrolyte into the housing of the battery cell 5 .

[0080] By adopting the above scheme, the gas extracted before injecting the target gas is the air in the shell, and after the air is extracted, a negative pressure is formed in the shell, which is convenient for the injection of the target gas; after the target gas is injected, the target gas is the main gas in the shell, and after the target gas is extracted, a negative pressure is formed in the shell, which is convenient for the injection of the electrolyte.

[0081] In some embodiments, during the process of injecting electrolyte into the shell, the air pressure in the shell is controlled to be lower than the air pressure in the injection container 4 to speed up the speed at which the electrolyte in the injection container 4 flows into the shell.

[0082] There are three ways to control the air pressure in the shell to be lower than the air pressure in the liquid injection container 4. One way is to increase the air pressure in the liquid injection container 4, another way is to reduce the air pressure in the shell, and another way is to increase the air pressure in the liquid injection container 4 while reducing the air pressure in the shell. The embodiments of the present application are not limited to this.

[0083] Since the air pressure in the shell is lower than the air pressure in the liquid injection container 4 , the electrolyte in the liquid injection container 4 is accelerated to flow toward the shell under the impetus of the air pressure in the liquid injection container 4 , thereby improving the liquid injection efficiency.

[0084] For example, in some embodiments, injecting electrolyte into the shell includes: injecting gas into the liquid injection container 4 to control the gas pressure in the shell to be lower than the gas pressure in the liquid injection container 4 .

[0085] The gas introduced into the liquid injection container 4 may be the target gas mentioned above, or other gases, for example, Figure 6 As shown, the gas injection end 22 of the gas injection assembly 2 of the above embodiment can be connected to the liquid injection container 4 to inject the gas in the gas storage container 3 into the liquid injection container 4 to increase the gas pressure in the liquid injection container 4.

[0086] By adopting the above-mentioned scheme, injecting gas into the liquid injection container 4 can increase the air pressure in the liquid injection container 4, thereby making the air pressure in the shell lower than the air pressure in the liquid injection container 4. As the injection of the electrolyte progresses, the speed of injecting gas into the liquid injection container 4 can be flexibly adjusted, thereby adjusting the air pressure difference between the liquid injection container 4 and the shell in real time. The implementation of this air pressure control method is relatively simple, and the implementation method is flexible and controllable.

[0087] like Figure 7 As shown, in some embodiments, before injecting the electrolyte into the housing, the injection method further includes: drying the electrode assembly of the battery cell 5. That is, the injection method in this embodiment is as follows:

[0088] S30: Drying the electrode assembly of the battery cell 5 .

[0089] S31 : Injecting target gas into the casing of the battery cell 5 .

[0090] S32: Extracting the gas in the casing of the battery cell 5.

[0091] S33 : injecting electrolyte into the housing of the battery cell 5 .

[0092] The drying device may be an oven 6, etc. The battery cell 5 is placed in the oven 6. The oven 6 may be kept airtight during the drying of the battery cell 5 to reduce heat loss.

[0093] During the manufacturing process, the electrode assembly may absorb moisture from the surrounding environment. This moisture mixes into the electrolyte and may affect the ratio of the electrolyte. Drying the electrode assembly before injection can reduce the moisture in the electrode assembly, thereby reducing the effect of moisture on the ratio of the electrolyte, making the electrochemical performance of the battery cell 5 stable.

[0094] like Figure 8 As shown, in some embodiments, drying the electrode assembly of the battery cell 5 in the step S30 further includes:

[0095] S301: extracting the gas in the oven 6.

[0096] S302: Inject target gas into the oven 6.

[0097] In this step, the gas extraction component 1 of the above embodiment can be used to extract the gas in the oven 6, and the gas injection component 2 of the above embodiment can be used to inject the target gas into the oven 6. The working state of the drying process is as follows: Figure 2 As shown, specific reference is made to the above-mentioned embodiments of the liquid injection device, and the embodiments of the present application will not be repeated.

[0098] In addition, during the process of drying the electrode assembly of the battery cell 5 , the above-mentioned steps S301 and S302 may be cycled for multiple times, thereby ensuring that the water vapor in the shell of the battery cell 5 can be extracted more thoroughly.

[0099] By adopting the above scheme, during the process of drying the electrode assembly, the moisture in the electrode assembly evaporates and turns into water vapor. During the process of extracting the gas in the oven 6, this part of the gas containing water vapor is extracted, and then the target gas is injected into the oven 6 to replace the moist gas in the oven 6 and the shell of the battery cell 5 with the target gas, thereby preventing this part of the gas containing water vapor from remaining in the shell and affecting the drying effect of the electrode assembly.

[0100] It should be noted that in the above-mentioned embodiments of the liquid injection method, the two steps of injecting the target gas into the shell and extracting the gas in the shell of the battery cell 5 can be cycled once or multiple times to replace the gas in the shell of the battery cell 5 with the target gas as completely as possible, so as to avoid the gas insoluble in the electrolyte remaining in the shell of the battery cell 5 and affecting the injection efficiency of the electrolyte.

[0101] The features of the above-mentioned protected subjects and embodiments of the present application can refer to each other. If the structure permits, those skilled in the art can also flexibly combine the technical features in different embodiments to form more embodiments.

[0102] To summarize, in the embodiment of the present application, before injecting electrolyte into the shell, the target gas is introduced into the shell by using the gas injection component 2, the air in the shell is replaced by the target gas, and then the gas extraction component 1 is used to extract the gas in the shell, and finally the electrolyte is injected into the shell. During the injection process, even if there is residual target gas in the shell, since the target gas is soluble in the electrolyte, the residual gas has less resistance to the electrolyte injection process, thereby improving the injection efficiency.

[0103] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0104] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A liquid injection device, characterized in that: Used to inject electrolyte into the shell of a battery cell, comprising: An air extraction component, having an air extraction end, used to communicate with the gas inside the shell to extract the gas inside the shell; A gas injection assembly, comprising a gas inlet end and a gas injection end, wherein the gas inlet end is connected to a gas storage container, and the gas injection end is used to communicate with the gas inside the shell to inject the target gas in the gas storage container into the shell; The target gas in the gas storage container is a gas soluble in the electrolyte.

2. The liquid injection device according to claim 1, characterized in that: The solubility of the target gas in the gas storage container in the electrolyte is greater than 0.

1.

3. The liquid injection device according to claim 2, characterized in that: The target gas in the gas storage container is dry CO2 or CO gas.

4. The liquid injection device according to any one of claims 1 to 3, characterized in that: The gas injection assembly further includes a pressure regulating valve, which is disposed between the gas inlet end and the gas injection end and is used to control the gas flow velocity at the gas injection end.

5. A liquid injection method, characterized in that: include: Injecting a target gas into a housing of a battery cell, wherein the target gas is a gas soluble in an electrolyte; extracting gas from the housing of the battery cell; An electrolyte is injected into the housing of the battery cell.

6. The liquid injection method according to claim 5, characterized in that: The gas in the shell of the battery cell needs to be extracted before and after the target gas is injected into the shell.

7. The liquid injection method according to claim 5, characterized in that: During the process of injecting the electrolyte into the shell, the air pressure in the shell is controlled to be lower than the air pressure in the injection container, so as to speed up the speed at which the electrolyte in the injection container flows into the shell of the battery cell.

8. The liquid injection method according to claim 7, characterized in that: Injecting the electrolyte into the housing comprises: Gas is injected into the liquid injection container to control the gas pressure in the shell of the battery cell to be lower than the gas pressure in the liquid injection container.

9. The liquid injection method according to any one of claims 5 to 8, characterized in that: Before injecting the electrolyte into the housing of the battery cell, the injection method further includes: The electrode assembly of the battery cell is dried.

10. The liquid injection method according to claim 9, characterized in that: Drying the electrode assembly of the battery cell further comprises: Extract the gas in the oven; The target gas is injected into the oven.

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