A liquid injection apparatus

Abstract

The utility model provides a kind of liquid injection equipment, including liquid injection container and electric capacity detection device, the liquid injection container can accommodate electrolyte, and electrolyte can be injected into electric core;The electric capacity detection device is arranged on the liquid injection container, and the electric capacity detection device can detect the parasitic capacitance change between it and the electrolyte in the liquid injection container, to detect the liquid level height change of the electrolyte in the liquid injection container.In the present application, the parasitic capacitance change between the electric capacity detection device and the electrolyte in the liquid injection container is detected, when the liquid injection container injects electrolyte into electric core, the electric capacity detection device can detect the liquid level height change of the electrolyte in the liquid injection container according to parasitic capacitance change, determine specific electrolyte injection amount, and accurate control can be realized to electrolyte injection amount.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a liquid injection device. Background Technology

[0002] As applications demand higher cycle life from battery cells, the development of battery cells is gradually moving towards longer cycle life. To achieve higher cycle life, the amount of electrolyte inside the battery cell needs to be further increased, which undoubtedly brings significant challenges to the electrolyte injection process in battery cell manufacturing.

[0003] Currently, the electrolyte injection process for battery cells typically relies on alternating positive and negative pressure cycles within an injection machine to propel the electrolyte into the cell. From a microscopic perspective, this process involves filling the pores of the electrode material inside the cell with electrolyte. During injection, as the electrolyte volume increases, the gas originally present within the pores of the electrode material is compressed. This gas pressure hinders further electrolyte injection into the pores, causing the injection rate to gradually decrease until an equilibrium state is reached (where some compressed gas remains inside the electrode, preventing the electrolyte from wetting that area). In this process, the injection time and the amount of electrolyte injected are not linearly related, making it impossible to accurately determine the injection volume in a single injection cycle or when the cell reaches equilibrium. This can easily lead to excessively long injection times, affecting injection efficiency, or excessively short injection times, resulting in insufficient electrolyte injection and affecting injection quality. Utility Model Content

[0004] The present invention provides an injection device that can improve the technical problem that when the electrolyte injection volume cannot be accurately controlled, the injection time is too long, thus affecting the injection efficiency, and the injection time is too short, resulting in insufficient electrolyte injection volume, thus affecting the injection quality.

[0005] An embodiment of this utility model provides a liquid injection device, comprising:

[0006] An electrolyte injection container, capable of holding electrolyte and injecting electrolyte into the battery cell; and,

[0007] A capacitance detection device is disposed on a liquid injection container and is capable of detecting changes in parasitic capacitance between itself and the electrolyte in the liquid injection container, thereby detecting changes in the liquid level of the electrolyte in the liquid injection container.

[0008] In the electrolyte injection device of this embodiment, precise electrolyte injection is achieved by monitoring the changes in parasitic capacitance between the injection container and the battery cell using a capacitance detection device. Specifically, during the process of injecting electrolyte into the battery cell, the capacitance detection device collects data on the changes in parasitic capacitance caused by the electrolyte in the injection container in real time, and accurately judges the trend of liquid level change based on this data, thereby determining the specific amount of electrolyte to be injected. The electrolyte injection device of this embodiment can precisely control the amount of electrolyte injected, avoiding both inefficiency caused by excessively long injection time and insufficient electrolyte injection due to insufficient injection time, ultimately achieving precise control of the amount of electrolyte injected and effective assurance of injection quality.

[0009] In one embodiment, the injection container includes a sidewall that encloses a cavity capable of containing electrolyte. The capacitance detection device is disposed on the side of the sidewall away from the cavity and is capable of detecting the parasitic capacitance change between the sidewall and the electrolyte in the cavity, thereby detecting the change in the electrolyte level in the injection container.

[0010] In the liquid injection device of this embodiment, by placing the capacitance detection device outside the receiving cavity, it can be prevented from being corroded by the electrolyte inside the receiving cavity, thereby reducing the wear and tear of the liquid injection device; at the same time, it can also avoid the risk of surface crystallization of the device caused by prolonged direct contact with the electrolyte.

[0011] In one embodiment, the liquid injection device further includes a fixing layer, the two opposite sides of which are connected to the capacitance detection device and the sidewall, respectively.

[0012] In the liquid injection device of this embodiment, the fixing layer allows the capacitance detection device to be attached to the side wall, ensuring a tighter connection between the capacitance detection device and the liquid injection container, thereby improving the accuracy of the capacitance detection device in detecting changes in the liquid level of the electrolyte in the liquid injection container.

[0013] In one embodiment, the combined thickness of the sidewall and the fixing layer is less than 5 mm.

[0014] In the liquid injection device of this embodiment, the superimposed thickness of the sidewall and the fixing layer is less than 5mm, which can avoid affecting the penetration effect of the capacitance detection device and ensure the accuracy of the capacitance detection device in detecting the change in the liquid level of the electrolyte in the injection container.

[0015] In one embodiment, the sidewall is made of a non-metallic material that is not capacitive.

[0016] In the liquid injection device of this embodiment, the sidewall material is a non-metallic material that is not sensitive to capacitance, which can avoid interference when the capacitance detection device detects the parasitic capacitance change between it and the electrolyte in the containment cavity.

[0017] In one embodiment, the upper and lower ends of the receiving cavity are aligned with the upper and lower ends of the capacitance detection device, respectively, or the receiving cavity is located between the upper and lower ends of the capacitance detection device.

[0018] In the liquid injection device of this embodiment, the position of the receiving cavity and the capacitance detection device are matched to ensure that the capacitance detection device can accurately detect the liquid level change of the electrolyte in the upper and lower ends of the receiving cavity.

[0019] In one embodiment, the liquid injection device further includes a tray capable of accommodating the battery cell, and the tray is connected to the liquid injection container.

[0020] In the electrolyte injection device of this embodiment, when the electrolyte injection container is connected to the battery cell for electrolyte injection, the position of the electrolyte injection container can be positioned by the tray to ensure that the electrolyte injection container can stably inject electrolyte into the battery cell.

[0021] In one embodiment, the injection container has an injection port for injecting electrolyte, the tray is detachably connected to the injection container, and the injection container can connect the injection port to the battery cell on the tray by connecting to the tray.

[0022] In the liquid injection device of this embodiment, when the liquid injection container is installed on the tray, the injection port can be aligned with the battery cell on the tray to directly complete the connection with the battery cell, which can realize the rapid connection between the liquid injection container and the battery cell and ensure the stability between the liquid injection container and the battery cell.

[0023] In one embodiment, the injection container has a flexible connector disposed at the injection port, and the flexible connector can abut against or embed itself into the battery cell when the injection container is connected to the tray, so as to connect the injection port to the battery cell on the tray.

[0024] In the liquid injection device of this embodiment, when the liquid injection container is installed on the tray, the flexible joint is pressed against the injection hole of the battery cell for injecting electrolyte, which can realize the connection between the injection port of the liquid injection container and the injection hole of the battery cell, and ensure the sealing by deformation to prevent electrolyte leakage during the liquid injection process.

[0025] In one embodiment, the injection device further includes:

[0026] The electrolyte injection machine is capable of injecting the electrolyte in the injection container into the battery cell;

[0027] A conversion module, connected to the capacitance detection device, converts the capacitance change detected by the capacitance detection device into a signal, the signal including a voltage signal and / or a frequency signal; and,

[0028] The control module is connected to both the conversion module and the liquid injection machine. The control module can judge the signal converted by the conversion module and output a switch signal to control the liquid injection machine to inject the electrolyte in the liquid injection container into the battery cell, and / or output continuous liquid level data of the liquid level change of the electrolyte in the liquid injection container.

[0029] In the electrolyte injection device of this embodiment, when the electrolyte level in the injection container changes, the change in dielectric constant between the electrolyte and the capacitance detection device causes a change in capacitance value. The capacitance detection device can detect the amount of capacitance change caused by this change in capacitance value. The conversion module can convert the amount of capacitance change detected by the capacitance detection device into a signal and input the signal to the control module. The control module performs threshold judgment on the signal and outputs a switch signal to control the injection machine to inject the electrolyte in the injection container into the battery cell. It can also simultaneously output continuous level data of the electrolyte level change in the injection container.

[0030] In one embodiment, the liquid injection machine is provided with a sealed cavity, and the liquid injection container and the capacitor detection device are both disposed in the sealed cavity. The liquid injection machine is capable of injecting the electrolyte in the liquid injection container into the battery cell through a positive and negative pressure nitrogen liquid injection process.

[0031] In the electrolyte injection equipment of this embodiment, the electrolyte injection machine can effectively improve the uniformity and accuracy of electrolyte injection through positive and negative pressure nitrogen injection process, reduce the defect rate in production, and improve the overall performance and safety of the battery.

[0032] The beneficial effects of the embodiments of this utility model are as follows:

[0033] In embodiments of this invention, a capacitance detection device detects the parasitic capacitance change between the device and the electrolyte in the injection container. When the injection container injects electrolyte into the cell, the capacitance detection device can detect the change in electrolyte level in the injection container based on the parasitic capacitance change, and determine the specific electrolyte injection amount. This allows for precise control of the electrolyte injection amount. Through the above process, the technical problems of excessively long injection time affecting injection efficiency and insufficient electrolyte injection amount affecting injection quality when the electrolyte injection amount cannot be precisely controlled can be improved. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the assembled structure of the liquid injection container, capacitance detection device, and fixing layer provided in an embodiment of this utility model;

[0036] Figure 2 This is a schematic diagram of the structure of the liquid injection container, capacitance detection device, and fixing layer before assembly, provided in an embodiment of this utility model;

[0037] Figure 3 This is a schematic diagram of the assembled structure of the sidewall, capacitance detection device, and fixing layer provided in an embodiment of this utility model;

[0038] Figure 4 This is a schematic diagram of the structure of the liquid injection container, capacitance detection device, and tray provided in an embodiment of this utility model;

[0039] Figure 5 This is a schematic diagram of the structure of the liquid injection container, capacitance detection device, tray, and liquid injection machine provided in the embodiments of this utility model;

[0040] 1. Injection container; 11. Side wall; 12. Receiving cavity; 13. Injection port; 14. Flexible connector;

[0041] 2. Capacitance detection device;

[0042] 3. Battery cells;

[0043] 4. Fixed layer;

[0044] 5. Pallet;

[0045] 6. Liquid injection machine; 61. Sealing chamber; 62. Sealing cover. Detailed Implementation

[0046] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present utility model and are not intended to limit the present utility model. In the present utility model, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device.

[0047] It should be noted that in this application, "and / or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the related objects before and after it are in an "or" relationship.

[0048] An embodiment of this utility model provides a liquid injection device, combined with Figure 1-4 It is known that the device includes an electrolyte container 1 and a capacitance detection device 2. The electrolyte container 1 can contain electrolyte and inject electrolyte into the battery cell 3. The capacitance detection device 2 is installed on the electrolyte container 1 and can detect the parasitic capacitance change between it and the electrolyte in the electrolyte container 1, so as to detect the change in the electrolyte level in the electrolyte container 1.

[0049] In the electrolyte injection device of this embodiment, precise electrolyte injection is achieved by monitoring the changes in parasitic capacitance between the electrolyte injection container 1 and the battery cell 3 through the capacitance detection device 2. Specifically, during the process of injecting electrolyte into the battery cell 3, the capacitance detection device 2 collects data on the changes in parasitic capacitance caused by the electrolyte in the electrolyte injection container 1 in real time, and accurately judges the trend of liquid level change based on this data, thereby determining the specific amount of electrolyte injected. The electrolyte injection device of this embodiment can precisely control the amount of electrolyte injected, avoiding the problem of low efficiency caused by excessive injection time, and preventing the phenomenon of insufficient electrolyte injection caused by insufficient injection time, ultimately achieving precise control of the amount of electrolyte injected and effective assurance of injection quality.

[0050] In one embodiment, the injection container 1 includes a sidewall 11, which encloses a cavity 12 to contain electrolyte. The cavity 12 is disposed on the side of the sidewall 11 away from the cavity 12 and can detect the parasitic capacitance change between the sidewall 11 and the electrolyte in the cavity 12 to detect the change in the electrolyte level in the injection container 1.

[0051] By placing the capacitance detection device 2 outside the receiving cavity 12, it can be prevented from being corroded by the electrolyte inside the receiving cavity 12, thereby reducing the wear and tear of the liquid injection equipment; at the same time, it can also avoid the risk of crystallization on the surface of the device caused by prolonged direct contact with the electrolyte.

[0052] In one embodiment, the injection device further includes a fixing layer 4, with its opposite sides connected to the capacitance detection device 2 and the side wall 11, respectively.

[0053] The fixing layer 4 allows the capacitance detection device 2 to be attached to the side wall 11, ensuring a tighter connection between the capacitance detection device 2 and the liquid injection container 1, thereby improving the accuracy of the capacitance detection device 2 in detecting changes in the liquid level of the electrolyte in the liquid injection container 1.

[0054] For example, the fixing layer 4 can be a 3M adhesive layer applied to the sidewall 11; it can also be replaced with double-sided tape or other fixing structures.

[0055] In one embodiment, the combined thickness of the sidewall 11 and the fixing layer 4 is less than 5 mm, which can avoid affecting the penetration effect of the capacitance detection device 2 and ensure the accuracy of the capacitance detection device 2 in detecting the change in the liquid level of the electrolyte in the injection container 1.

[0056] For example, the thickness of the sidewall 11 is between 3mm and 4mm, such as 3mm or 4mm, or any size between 3mm and 4mm; the thickness of the fixing layer 4 is less than 1mm, approximately 0.5mm.

[0057] In one embodiment, the sidewall 11 is made of a non-metallic material that is not sensitive to capacitance, so as to avoid interference when the capacitance detection device 2 detects the parasitic capacitance change between it and the electrolyte in the containment cavity 12.

[0058] In one embodiment, the sidewall 11 is made of polytetrafluoroethylene.

[0059] In one embodiment, the upper and lower ends of the receiving cavity 12 are aligned with the upper and lower ends of the capacitance detection device 2, or the receiving cavity 12 is located between the upper and lower ends of the capacitance detection device 2, so as to ensure that the capacitance detection device 2 can accurately detect the liquid level change of the electrolyte within the range of the upper and lower ends of the receiving cavity 12.

[0060] In one embodiment, the liquid injection device further includes a tray 5, which can accommodate the battery cell 3 and is connected to the liquid injection container 1. The tray 5 positions the liquid injection container 1, which can ensure that the liquid injection container 1 can stably inject electrolyte into the battery cell 3.

[0061] In one embodiment, the injection container 1 has an injection port 13 for injecting electrolyte, the tray 5 is detachably connected to the injection container 1, and the injection container 1 can connect the injection port 13 to the battery cell 3 on the tray 5 by connecting to the tray 5.

[0062] When the injection container 1 is installed on the tray 5, the injection port 13 can be aligned with the battery cell 3 on the tray 5 to complete the connection with the battery cell 3. This enables the injection container 1 and the battery cell 3 to be connected quickly and ensures the stability between the injection container 1 and the battery cell 3.

[0063] For example, the tray 5 and the liquid injection container 1 can be detachably connected by a snap-fit ​​structure.

[0064] In one embodiment, the injection container 1 has a flexible connector 14, which is disposed at the injection port 13. The flexible connector 14 can abut against or embed itself into the battery cell 3 when the injection container 1 is connected to the tray 5, so as to connect the injection port 13 to the battery cell 3 on the tray 5.

[0065] When the injection container 1 is installed on the tray 5, the flexible connector 14 is pressed against the injection hole of the battery cell 3 for injecting electrolyte, which can connect the injection port 13 of the injection container 1 with the injection hole of the battery cell 3, and ensure the sealing through deformation to prevent electrolyte leakage during the injection process.

[0066] For example, there are multiple injection ports 13 and multiple flexible connectors 14. Multiple flexible connectors 14 are respectively installed at multiple injection ports 13. Through the cooperation of multiple injection ports 13 and multiple flexible connectors 14, multiple cells 3 can be injected with liquid at the same time.

[0067] In one embodiment, the flexible joint 14 is made of rubber. When the rubber-made flexible joint 14 is pressed against the injection port of the battery cell 3 for injecting electrolyte, it can deform rapidly to ensure a seal between the battery cell 3 and the injection port 13.

[0068] In one embodiment, combined with Figure 5 It can be seen that the liquid injection equipment also includes:

[0069] The electrolyte injection machine 6 can inject the electrolyte in the electrolyte injection container 1 into the battery cell 3.

[0070] The conversion module, connected to the capacitance detection device 2, converts the capacitance change detected by the capacitance detection device 2 into a signal, including a voltage signal and / or a frequency signal; and,

[0071] The control module, conversion module, and liquid injection machine 6 are all connected to the control module. The control module can judge the signal converted by the conversion module and output a switch signal to control the liquid injection machine 6 to inject the electrolyte in the liquid injection container 1 into the battery cell 3, and / or output continuous liquid level data of the liquid level change of the electrolyte in the liquid injection container 1.

[0072] When the electrolyte level in the injection container 1 changes, the change in dielectric constant between the electrolyte and the capacitance detection device 2 causes a change in capacitance. The capacitance detection device 2 can detect the amount of capacitance change. The conversion module can convert the amount of capacitance change detected by the capacitance detection device 2 into a signal and input the signal to the control module. The control module performs threshold judgment on the signal and outputs a switch signal to control the injection machine 6 to inject the electrolyte in the injection container 1 into the battery cell 3. It can also simultaneously output continuous level data of the electrolyte level change in the injection container 1.

[0073] In one embodiment, the electrolyte injection device may have a display screen that can display continuous liquid level data of the electrolyte level change in the injection container 1; or it may have a speaker that can provide real-time prompts of the continuous liquid level data of the electrolyte level change via voice broadcast.

[0074] In one embodiment, the conversion module can be a differential amplifier circuit, capable of converting the capacitance change detected by the capacitance detection device 2 during parasitic capacitance changes into a voltage signal; or a high-frequency oscillation circuit, capable of converting the capacitance change detected by the capacitance detection device 2 during parasitic capacitance changes into a frequency signal. The control module is a control chip (ASIC / FPGA). The specific control principles and circuit designs described above are relatively conventional, and therefore will not be elaborated upon in this application.

[0075] In one embodiment, the capacitance detection device 2 includes a capacitance sensor that can detect changes in parasitic capacitance between itself and the electrolyte in the injection container 1, so as to detect changes in the liquid level of the electrolyte in the injection container 1.

[0076] For example, when the capacitive sensor is used for the first time, it can be calibrated. After calibration, the change in the liquid level of the electrolyte in the injection container 1 can be detected by detecting the change in the parasitic capacitance between the sensor and the electrolyte in the injection container 1.

[0077] The calibration process is as follows: Electrolyte is gradually added into the receiving cavity 12 of the injection container 1. Every 1 / 20 of the height, the output analog signal of the capacitive sensor is recorded. There are two modes: voltage signal and current signal, which are 0-5V and 0-20mA respectively. The signal is calibrated to correspond with the liquid level of the electrolyte, that is, the correspondence between the liquid level change of the injection container 1 and the signal detected by the capacitive sensor is determined. (This operation only needs to be performed once. The relationship is one-to-one without disassembly and can be used continuously.)

[0078] In one embodiment, the liquid injection machine 6 is provided with a sealed cavity 61, and both the liquid injection container 1 and the capacitance detection device 2 are disposed within the sealed cavity 61. The liquid injection machine 6 can inject the electrolyte in the liquid injection container 1 into the battery cell 3 through a positive and negative pressure nitrogen liquid injection process. The liquid injection machine 6 using the positive and negative pressure nitrogen liquid injection process is only one implementation of this embodiment, and it can also be replaced by other devices capable of injecting electrolyte into the battery cell 3.

[0079] For example, the positive and negative pressure nitrogen injection process may include: (1) positive pressure injection, in which a certain positive pressure is applied during the injection process to promote the electrolyte to fill the tiny pores of the cell 3 evenly; (2) negative pressure injection, in which a negative pressure is applied after injection to help expel excess electrolyte and air, and further improve the uniform distribution of liquid inside the battery; (3) helium filling, in which helium is injected into the cell 3 after the injection is completed. Helium is an inert gas with stable properties and does not easily react with other substances; (4) alternating positive and negative pressure, in which the distribution of electrolyte inside the battery is further optimized by alternating the application of positive and negative pressure.

[0080] In one embodiment, the injection machine 6 has a movable sealing cover 62, which can be used to open and close the sealing cavity 61. The injection container 1 and the capacitance detection device 2 can be placed in the sealing cavity 61 by opening the sealing cover 62, and then the sealing cover 62 can be closed to seal the sealing cavity 61.

[0081] In one embodiment, the liquid injection device also includes a tray 5 and a liquid injection machine 6. The liquid injection machine 6 is provided with a sealed cavity 61. The tray 5 can accommodate the battery cell 3 and is fixedly or detachably connected to the liquid injection container 1. The tray 5, the liquid injection container 1 and the capacitance detection device 2 are all arranged in the sealed cavity 61. The liquid injection machine 6 can inject the electrolyte in the liquid injection container 1 into the battery cell 3 in the tray 5 through a positive and negative pressure nitrogen liquid injection process.

[0082] The specific operation of this injection equipment during injection processing can be as follows:

[0083] The battery cell 3 is loaded on the tray 5, and then the liquid injection container 1 is installed on the tray 5. The position of the liquid injection container 1 is positioned by the tray 5, which can ensure that the liquid injection container 1 and the battery cell 3 are aligned.

[0084] Start the capacitance detection device 2 and inject electrolyte into the liquid injection container 1. Then, put the assembled tray 5, liquid injection container 1 and capacitance detection device 2 into the sealed cavity.

[0085] The injection machine 6 introduces nitrogen gas under positive and negative pressure into the sealed cavity 61 and injects the liquid according to the process parameters;

[0086] The capacitance detection device 2 monitors the change in the liquid level of the electrolyte in the injection container 1 in real time.

[0087] The embodiments of this utility model have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this utility model. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A liquid injection device, characterized in that, include: The electrolyte injection container is capable of holding electrolyte and injecting electrolyte into the battery cell; and, A capacitance detection device is disposed on the electrolyte injection container, and the capacitance detection device is capable of detecting the parasitic capacitance change between itself and the electrolyte in the electrolyte injection container, so as to detect the change in the electrolyte level in the electrolyte injection container.

2. The liquid injection device according to claim 1, characterized in that, The injection container includes a sidewall that encloses a cavity capable of holding electrolyte. The capacitance detection device is disposed on the side of the sidewall away from the cavity and is capable of detecting the parasitic capacitance change between the sidewall and the electrolyte in the cavity, thereby detecting the change in the electrolyte level in the injection container.

3. The liquid injection device according to claim 2, characterized in that, The liquid injection device also includes a fixing layer, with the opposite sides of the fixing layer connected to the capacitance detection device and the side wall, respectively.

4. The liquid injection device according to claim 3, characterized in that, The combined thickness of the sidewall and the fixing layer is less than 5 mm.

5. The liquid injection device according to claim 2, characterized in that, The sidewall is made of a non-metallic material that is not capacitive.

6. The liquid injection device according to claim 2, characterized in that, The upper and lower ends of the receiving cavity are aligned with the upper and lower ends of the capacitance detection device, respectively, or the receiving cavity is located between the upper and lower ends of the capacitance detection device.

7. A liquid injection device according to any one of claims 1-6, characterized in that, The liquid injection device also includes a tray capable of accommodating the battery cell, and the tray is connected to the liquid injection container.

8. The liquid injection device according to claim 7, characterized in that, The injection container has an injection port for injecting electrolyte. The tray is detachably connected to the injection container, and the injection container can connect the injection port to the battery cell on the tray by connecting to the tray.

9. The liquid injection device according to claim 8, characterized in that, The injection container has a flexible connector located at the injection port. When the injection container is connected to the tray, the flexible connector can abut against or embed itself into the battery cell to connect the injection port to the battery cell on the tray.

10. A liquid injection device according to any one of claims 1-6, characterized in that, The injection device also includes: The electrolyte injection machine is capable of injecting the electrolyte in the injection container into the battery cell; A conversion module, connected to the capacitance detection device, converts the capacitance change detected by the capacitance detection device into a signal, the signal including a voltage signal and / or a frequency signal; and, The control module is connected to both the conversion module and the liquid injection machine. The control module can judge the signal converted by the conversion module and output a switch signal to control the liquid injection machine to inject the electrolyte in the liquid injection container into the battery cell, and / or output continuous liquid level data of the liquid level change of the electrolyte in the liquid injection container.

11. The liquid injection device according to claim 10, characterized in that, The liquid injection machine is equipped with a sealed cavity, and the liquid injection container and the capacitor detection device are both located in the sealed cavity. The liquid injection machine can inject the electrolyte in the liquid injection container into the battery cell through a positive and negative pressure nitrogen liquid injection process.

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