Method and device for avoiding electrolyte residue crystallization

Abstract

The application discloses a method and device for avoiding electrolyte residual crystallization, comprising the following steps: repeatedly pasting a film on the liquid injection port of an electric core to obtain a composite film layer, the composite film layer comprising a first film layer, a second film layer and a third film layer, the first film layer being pasted tightly to the inner side wall of the liquid injection port; after a first liquid injection process, the third film layer is removed; after a negative pressure formation process, the second film layer is removed; after a second liquid injection process, the first film layer is removed. The method provided by the application effectively solves the adverse effects of electrolyte crystallization on the compaction of the liquid injection port and the welding of the sealing nail after the completion of the liquid injection. Meanwhile, the application is implemented without changing the original production process and equipment, and can greatly improve the production efficiency and product yield rate while ensuring the performance of the electric core.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery cleaning technology, and in particular to a method and apparatus for preventing electrolyte residue crystallization. Background Technology

[0002] The concepts of "carbon peaking" and "carbon neutrality," proposed during the 2021 Two Sessions, have once again brought new clean energy to the public eye and accelerated the demand for new energy vehicles in the domestic market. Among them, lithium-ion batteries, as the most basic power unit of new energy vehicles, are facing a supply shortage. Therefore, improving production efficiency and product yield while ensuring product quality is particularly crucial.

[0003] The fabrication of lithium-ion batteries includes an electrolyte filling process. During this process, the difference between the cell immersion rate and the electrolyte filling rate can cause electrolyte overflow. Treating this overflowing electrolyte increases production time and reduces efficiency. Therefore, preventing residual crystallization in the electrolyte is a pressing issue that needs to be addressed. Summary of the Invention

[0004] In view of this, this application proposes a method to avoid residual crystallization in the electrolyte, which can effectively solve the adverse effects of electrolyte crystallization on the compaction of the injection port and the welding of sealing pins after injection. At the same time, this application is carried out without changing the original production process and equipment, and can greatly improve production efficiency while ensuring cell performance.

[0005] In a first aspect, this application provides a method for avoiding residual crystallization in electrolyte, comprising at least the following steps:

[0006] The adhesive film is repeatedly applied to the liquid injection port of the battery cell to obtain a composite adhesive film layer. The composite adhesive film layer includes a first adhesive film layer, a second adhesive film layer and a third adhesive film layer. The first adhesive film layer is attached tightly to the inner wall of the liquid injection port.

[0007] After one injection process, the third adhesive film layer is removed;

[0008] After the negative pressure formation process, the second adhesive film layer is removed;

[0009] After the second injection process, the first adhesive film layer is removed.

[0010] In the above solution, the composite film layer effectively solves the adverse effects of electrolyte crystallization on the compaction of the injection port and the welding of sealing nails after injection.

[0011] Furthermore, the first adhesive film layer includes a first clamping portion, the second adhesive film layer includes a second clamping portion, and the third adhesive film layer includes a third clamping portion, with the length H of the first clamping portion, the second clamping portion, and the third clamping portion increasing sequentially.

[0012] In the above solution, clamping parts are provided for the first adhesive film layer, the second adhesive film layer and the third adhesive film layer, and the lengths of the first clamping part, the second clamping part and the third clamping part are different, which makes it easy to distinguish different adhesive films and facilitates the film peeling process.

[0013] Furthermore, the widths of the first adhesive film layer, the second adhesive film layer, and the third adhesive film layer are at least 1.5 times the outer diameter of the injection port.

[0014] In the above scheme, the widths of the first, second, and third adhesive films are within this range. The adhesive films can better cover the area around the injection port, preventing electrolyte residue from remaining around the injection port during the injection process and eliminating the adverse effects on subsequent injection port compaction.

[0015] Furthermore, the adhesive film is cut by an adhesive film cutting mechanism.

[0016] In the above scheme, adhesive films of different lengths can be cut using an adhesive film cutting mechanism.

[0017] Furthermore, the composite adhesive film layer is pressed into the injection port by the flattening component of the protective device, so that the adhesive film adheres to the injection port.

[0018] In the above scheme, when the composite film layer is pressed against the inner wall of the injection port, in order to prevent deviation in the film application process, the first adhesive film, the second adhesive film and the third adhesive film covering the injection port are accurately and tightly bonded to the inner wall of the injection port by the flattening component.

[0019] Furthermore, the battery cell is positioned by the positioning component of the protective device, the adhesive film cut by the adhesive film cutting mechanism is covered by the adhesive film clamps to the injection port, and the flattening component presses the adhesive film into and adheres it tightly to the inner wall of the injection port.

[0020] In the above solution, the composite film layer formed by the film application process is used to deal with the electrolyte contamination suffered by the battery cell during the first electrolyte injection, negative pressure formation and the second electrolyte injection. It can effectively solve the adverse effects of electrolyte crystallization on the compaction of the injection port and the welding of the sealing nail after the electrolyte injection is completed.

[0021] Secondly, this application provides a protective device to prevent electrolyte residue crystallization, the protective device including adhesive film grippers for gripping adhesive film and performing film application and peeling processes; and

[0022] A smoothing component, comprising a main body and a puncture portion, wherein the main body is provided with a smoothing surface, the main body cooperates with the injection port, the main body uses the smoothing surface to adhere the adhesive film to the inner wall of the injection port, and the puncture portion punctures the adhesive film layer formed by the film application process.

[0023] In the above scheme, the film is simultaneously picked up, applied and peeled off by the film clamp, and the composite film layer is pressed against the inner wall of the injection port and flattened by the flattening component. This is done without changing the original production process and equipment, which can greatly improve production efficiency and product yield while ensuring the performance of the battery cell.

[0024] Furthermore, the kneading surface of the main body is provided with threads, which are used to further fit the adhesive film to the inner wall of the injection port.

[0025] In the above solution, the thread can better adhere the adhesive film to the inner wall of the injection port, preventing air bubbles from forming on the inner wall of the injection port.

[0026] Furthermore, the protective device is also equipped with a positioning element, which is used to position the battery cell.

[0027] In the above scheme, the accurate positioning of the battery cell is achieved through the positioning component structure, thereby ensuring the positioning accuracy of the flattening component when pressing the composite film layer against the inner wall of the injection port.

[0028] Furthermore, the protective device also includes a film cutting mechanism, which includes a first clamping member and a second clamping member, wherein the first clamping member is movable relative to the second clamping member.

[0029] In the above scheme, the required film length is different for battery cells of different widths, so different lengths of film are cut by a movable first clamping member.

[0030] Furthermore, the film cutting mechanism also includes a cutter. After the second clamping member moves to the required length of the film layer, the cutter cuts the film, and the film gripper delivers the film to the injection port.

[0031] In the above solution, a cutter is installed on the protective device to further facilitate the film cutting process. By adopting this technical solution, the electrolyte injection port area of ​​the battery cell can be protected, thereby minimizing the problem of electrolyte contamination of the battery cell and effectively solving the adverse effects of electrolyte crystallization on the compaction of the injection port and the welding of sealing pins after injection. Furthermore, this application is carried out without changing the original production process and equipment, and can significantly improve production efficiency while ensuring battery cell performance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the protective device provided in Embodiment 1 of this application;

[0033] Figure 2 This is a schematic diagram of the film cutting mechanism provided in this application;

[0034] Figure 3 This is a schematic diagram of the structure of the flattening component provided in Embodiment 1 of this application;

[0035] Figure 4 This is a schematic diagram of the structure of the composite membrane layer provided in this application;

[0036] Figure 5 This is a schematic diagram of the protective device provided in Embodiment 2 of this application;

[0037] Figure 6 This is a schematic diagram of the structure of the flattening component provided in Embodiment 3 of this application.

[0038] Figure label:

[0039] 1-Film cutting mechanism;

[0040] 11-Moving axis;

[0041] 12-First clamping element;

[0042] 13-Second clamping element;

[0043] 14-Cut knife;

[0044] 2- Protective devices;

[0045] 21-Film gripper; 211-Gripper section; 212-Rotating shaft;

[0046] 22-Positioning component; 221-Front clamping plate; 222-Double-side clamping plates;

[0047] 23-Smoothing part; 231-Main body; 232-Piercing part; 233-Thread;

[0048] 24-Visual inspection device;

[0049] 3-First adhesive film layer;

[0050] 31-First clamping part;

[0051] 4-Second adhesive film layer;

[0052] 41-Second clamping part;

[0053] 5-Third adhesive film layer;

[0054] 51-Third clamping part;

[0055] 6-Battery cell;

[0056] 61-Injection port. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0058] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0059] In the description of this specification, it should be understood that the directional terms such as "upper" and "lower" used in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should also be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0060] In recent years, lithium-ion batteries have been increasingly used in new energy applications, greatly facilitating people's lives. As the most basic power unit for new energy vehicles, lithium-ion batteries are facing a supply shortage, making it crucial to improve production efficiency while ensuring battery quality. The electrolyte plays a key role in lithium-ion batteries, conducting lithium ions and ensuring their movement between the positive and negative electrodes at a certain rate during charging and discharging to form the entire circuit and generate current. Specifically, the electrolyte consists of three parts:

[0061] Solvents are the main component of electrolytes, and the performance of the electrolyte is closely related to the performance of the solvent. In some embodiments, the solvents used in lithium-ion battery electrolytes include at least one of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). In practical applications, mixed solvents of ethylene carbonate (EC) and a chain carbonate, such as EC+DMC and EC+DEC, are excellent electrolytes for lithium-ion batteries.

[0062] In some embodiments, LiPF6 is the most commonly used lithium electrolyte salt, exhibiting good ionic conductivity and electrochemical stability in organic solvents. Furthermore, the LiPF6 electrolyte can form a protective film with the current collector Al, thereby reducing the corrosiveness of the electrolyte to the current collector Al. More importantly, carbonate electrolytes based on LiPF6 can form a solid electrolyte interface (SEI) at the graphite anode, protecting against adverse reactions between the electrolyte and the graphite anode and promoting good long-cycle performance of the lithium-ion battery.

[0063] Additives are numerous and varied, and the specific additives chosen differ depending on the application and performance requirements of different lithium-ion batteries. Additives used in electrolytes primarily serve three functions: First, improving the performance of the SEI film. Adding anisole or its halogenated derivatives to the lithium-ion battery electrolyte can improve the battery's cycle performance and reduce irreversible capacity loss. Second, reducing trace amounts of water and HF acid in the electrolyte. Lithium-ion batteries have strict requirements regarding the amount of water and acid in the electrolyte; in some implementations, carbodiimide compounds can prevent LiPF6 from hydrolyzing into acid. Third, preventing overcharging and over-discharging.

[0064] After the electrolyte is selected and prepared, injecting the electrolyte into the battery is one of the important steps in battery manufacturing. If too much electrolyte is injected, it will cause the battery to overheat or even fail directly. If too little electrolyte is injected, it will affect the battery's cycle life. The electrolyte injection process can be divided into three steps: primary electrolyte injection, negative pressure formation, and secondary electrolyte injection.

[0065] The first electrolyte injection process involves vacuuming before the first injection to remove gas from the pores of the electrode, which facilitates rapid wetting of the electrolyte injected during the first injection and shortens the settling time.

[0066] The negative pressure formation process, following the initial electrolyte injection, involves passing the battery through a high-temperature aging chamber for further negative pressure formation. This formation step is crucial in lithium-ion battery manufacturing, impacting performance factors such as capacity, cycle life, and high-temperature storage. During formation, the electrolyte undergoes reduction and decomposition on the negative electrode surface, forming an SEI (Solid Electrolyte Interface) film. It's important to note that the SEI film is a passivation film formed during the first cycle of a lithium-ion battery due to the reaction between the electrolyte and the negative electrode material at the solid-liquid interphase level. This film ensures the safety, reliability, and long cycle life of the cell during subsequent charge-discharge cycles.

[0067] The secondary electrolyte injection process is a replenishment process after the negative pressure formation process. Similar to the primary injection, it typically uses vacuum injection, with the injection volume controlled by a high-precision injection pump. The battery is weighed before injection and again afterward, and the weight is compared with the first weighing to verify the injection volume. The secondary injection process is usually followed by a sealing process. In some implementations, sealing methods include using rubber stoppers, laser sealing with aluminum sheets, or sealing with steel balls and resin adhesive.

[0068] In some embodiments, the injection nozzle is tightly fitted with the injection port 61 on the battery during a single injection process to prevent electrolyte overflow. However, due to the high viscosity and surface tension of the electrolyte, a certain amount of electrolyte will adhere to the injection nozzle. When the injection nozzle is fitted with the injection port 61, this portion of electrolyte will remain at the stepped position of the injection port 61.

[0069] Furthermore, due to the difference between the cell immersion speed and the electrolyte injection speed, the electrolyte inside the cell may overflow. After being left to stand at high temperature, crystals form at the injection port. This is the electrolyte overflow phenomenon in the electrolyte injection stage of lithium-ion batteries. After the electrolyte flows over the surface of the lithium-ion battery, crystals form, affecting the subsequent compaction process at the injection port.

[0070] Furthermore, the vacuuming stage of the negative pressure formation process also removes some electrolyte, causing it to accumulate around the injection port and exacerbating electrolyte crystallization. In the subsequent processing steps after the secondary injection process, sealing pins need to be fixed into the injection port. Residual electrolyte at the step of the injection port directly affects the welding quality of the sealing pins, often resulting in weld bursts and lower battery quality. Simultaneously, the electrolyte is corrosive and can easily corrode the lithium-ion battery casing, posing a threat to the safety of the battery during subsequent use.

[0071] Currently, the method for cleaning crystallizing electrolyte is to wipe it with non-woven cloth. The non-woven cloth wiping method relies on the equipment structure to wipe the injection port back and forth to remove the residual electrolyte and its crystals on the surface. The wiping effect is not obvious, and manual visual inspection and rework are required. In addition, the equipment cost is high, and the non-woven cloth cannot be reused, resulting in serious consumption.

[0072] In view of this, this application proposes a method to avoid residual crystallization in the electrolyte, effectively solving the adverse effects of electrolyte crystallization on the compaction of the injection port and the welding of sealing pins after injection. Furthermore, this application is carried out without changing the original production process and equipment, and can significantly improve production efficiency while ensuring cell performance.

[0073] The method for avoiding residual crystallization of electrolyte provided in this application is applicable to the electrolyte filling process of cylindrical battery filling machines, vacuum chamber filling machines, square aluminum shell battery filling machines, or soft-pack battery filling machines, etc. Of course, it can also be applied to the electrolyte filling process of other filling equipment, and is not limited to the electrolyte filling equipment provided above.

[0074] Example 1:

[0075] This application proposes a method to prevent residual electrolyte crystallization, which protects the electrolyte inlet 61 area of ​​the battery cell 6 from contamination by residual electrolyte. Before each electrolyte injection process, three layers of adhesive film are applied to the electrolyte inlet 61 of the battery cell 6. Simultaneously, a smoothing component 23 embedded in the electrolyte inlet 61 smooths the adhesive film layers within the hole, ensuring they adhere to the inner wall of the electrolyte inlet 61. After each electrolyte injection process, the outermost third adhesive film is removed to eliminate residual electrolyte around the electrolyte inlet 61. This prevents the formation of crystallized electrolyte around the electrolyte inlet 61 after high-temperature settling, thus ensuring the smooth operation of the negative pressure formation process and avoiding low production efficiency caused by downtime for wiping away crystallized electrolyte.

[0076] The adhesive film used in this application is a square film with a certain degree of hardness, which can cover the area around the injection port. In some embodiments, since the electrolyte has a certain degree of corrosiveness, in order to prevent the adhesive film from being corroded by the electrolyte during the injection process, the adhesive film of this application can be made of EPDM rubber, fluororubber or other rubber materials that are resistant to electrolyte corrosion.

[0077] Furthermore, the remaining two layers of adhesive film are peeled off after the negative pressure formation process and the secondary electrolyte injection process, respectively. This minimizes the problem of electrolyte contamination of the battery cell 6 and effectively solves the adverse effects of electrolyte crystallization on the compaction of the injection port 61 and the welding of the sealing nails after the electrolyte injection is completed. At the same time, this application is carried out without changing the original production process and equipment, and can greatly improve production efficiency while ensuring the performance of the battery cell 6.

[0078] Specifically, methods to avoid residual crystallization in the electrolyte can be roughly divided into four steps:

[0079] Step S10, film cutting process;

[0080] Step S20, cell 6 positioning process;

[0081] Step S30, film application process;

[0082] Step S40, the film removal process.

[0083] Figure 1 A schematic diagram of the structure of the protective device 2 provided in this application is shown below. Figure 1As shown, the above steps are achieved through the protective device 2. The following describes this solution in detail with reference to specific embodiments:

[0084] Step S10, film cutting process.

[0085] In step S10, the protective device 2 includes a film cutting mechanism 1, which cuts the film. Figure 2 This is a schematic diagram of the film cutting mechanism 1 provided in this application, as shown below. Figure 2 As shown, the film cutting mechanism 1 includes an arc-shaped moving shaft 11 and a first clamping member 12 connected to the moving shaft 11. The moving shaft 11 can drive the first clamping member 12 to move. Furthermore, the film cutting mechanism 1 also includes a second clamping member 13 and a cutter 14.

[0086] The first clamping member 12 is used to clamp the first end of the adhesive film. It is a U-shaped clamping plate structure with an opening. The end of the U-shaped clamping plate structure is connected to the arc-shaped moving shaft 11. The adhesive film passes through the opening of the first clamping member 12. When the arc-shaped moving shaft 11 drives the first clamping member 12 to move to a preset position along the length direction of the adhesive film, the first clamping member 12 clamps the adhesive film.

[0087] The second clamping member 13 is used to clamp the second end of the adhesive film and is fixedly mounted on the adhesive film cutting mechanism 1. The adhesive film can pass through the interior of the second clamping member 13 and be clamped by the second clamping member 13. In some embodiments, the second clamping member may consist of upper and lower clamping plates.

[0088] The cutter 14 is used to cut the adhesive film. The cutter 14 is positioned above the adhesive film and is arranged vertically. In some embodiments, the cutter 14 may be a hydraulic cutter, a ratchet cutter, a split-type hydraulic cutter, etc.

[0089] In practical applications, the first clamping member 12 can move relative to the second clamping member 13, and the cutter 14 is used to cut the adhesive film. After the position of the second clamping member 13 is determined, the first clamping member 12 moves to abut against the second clamping member 13, and the adhesive film passes through the first clamping member 12 and the second clamping member 13. At this time, the first clamping member 12 moves away from the second clamping member 13, and the length of the adhesive film that can be cut becomes longer.

[0090] The protective device 2 includes two adhesive film grippers 21. The adhesive film grippers 21 have a Y-shaped structure, meaning each gripper 21 includes a gripper portion 211 and a rotating shaft 212 connected to the closed end of the gripper portion 211. The gripper portion 211 can rotate under the drive of the rotating shaft 212. The adhesive film grippers 21 used in this application can be metal adhesive film grippers, plastic adhesive film grippers, etc. In some embodiments, the inner side of the adhesive film gripper 21 can be a smooth plane to prevent adhesion to the adhesive film during the gripping process.

[0091] In practical application, the adhesive film passes through the first clamping member 12 and the second clamping member 13. When the first clamping member 12 moves away from the second clamping member 13 to the required adhesive film length, the first clamping member 12 and the second clamping member 13 clamp the adhesive film. The two adhesive film grippers 21 of the protective device 2 are inserted into the cutting position of the adhesive film and clamp the adhesive film. The cutter 14 cuts the adhesive film outside the adhesive film grippers 21. The rotating shaft 212 rotates 90 degrees to pick up the adhesive film and obtain the first adhesive film of the required length. The above process is repeated to obtain the second and third adhesive films of the required length.

[0092] The outer diameter D of the liquid injection port 61 of the battery cell 6 is generally 8mm. In this application, the first, second, and third adhesive films have the same length, and the width of the first, second, and third adhesive films is at least 1.5 times the outer diameter D of the liquid injection port 61. Optionally, the width of the first, second, and third adhesive films can be 1.5 times, 1.8 times, 2.0 times, 2.3 times, 2.6 times, or 3 times the outer diameter D of the liquid injection port 61, that is, the width of the first, second, and third adhesive films is 12mm, 14.4mm, 16mm, 18.4mm, 20.8mm, 24mm, etc., which can be selected according to the actual outer diameter of the liquid injection port 61, and is not limited here. By setting the widths of the first, second, and third adhesive films within this range, the films can better cover the area around the injection port 61, preventing electrolyte residue from remaining around the injection port 61 during the injection process and eliminating any adverse effects on the subsequent compaction of the injection port 61. Preferably, the widths of the first, second, and third adhesive films can be 1.5 to 2 times the outer diameter D of the injection port 61.

[0093] It should be noted that the adhesive film cut by the adhesive film cutting mechanism 1 includes an adhesive film body and a clamping part, namely, the first adhesive film includes a first clamping part 31, the second adhesive film includes a second clamping part 41, and the third adhesive film includes a third clamping part 51. The first clamping part 31, the second clamping part 41 and the third clamping part 51 are the free ends of the adhesive film. The first adhesive film, the second adhesive film and the third adhesive film are raised on the side of the battery cell 6 to form the clamping part.

[0094] The first clamping part 31 is the free end of the adhesive film, that is, the first adhesive film is raised on the side of the battery cell 6 to form the first clamping part 31. The adhesive film claw 21 can perform the peeling process of the first adhesive film by clamping the first clamping part 31. In some embodiments, the length of the first clamping part 31 is minimal.

[0095] The second clamping portion 41 is the free end of the adhesive film, that is, the second adhesive film is raised on the side of the battery cell 6 to form the second clamping portion 41. The adhesive film gripper 21 can perform the peeling process of the first adhesive film by clamping the second clamping portion 41. In some embodiments, the length of the second clamping portion 41 is greater than the length of the first clamping portion 31.

[0096] The third clamping part 51 is the free end of the adhesive film, that is, the third adhesive film is raised on the side of the battery cell 6 to form the third clamping part 51. The adhesive film claw 21 can perform the peeling process of the first adhesive film by clamping the third clamping part 51. In some embodiments, the length of the third clamping part 51 is greater than the length of the first clamping part 31 and the second clamping part 41.

[0097] Specifically, during the subsequent film application process, the adhesive film grippers 21 apply the film longitudinally. When the main body of the adhesive film covers the top surface of the battery cell 6, the adhesive film located on the side of the battery cell 6 is rotated and bent by the adhesive film grippers 21 to form a clamping part. During the three adhesive cutting processes, the required length of the adhesive film remains unchanged, and the distance between the two adhesive film grippers 21 gradually shortens. This results in the bending portion of the adhesive film located on the side of the battery cell 6 increasing sequentially during the subsequent covering process. That is, the raised length H of the first clamping part 31, the second clamping part 41, and the third clamping part 51 increases sequentially, facilitating the subsequent film peeling process.

[0098] Step S20, cell 6 positioning process.

[0099] In step S20, the positioning of the battery cell 6 is achieved by the positioning element 22 of the protective device 2.

[0100] In this application, the positioning element 22 is a three-sided clamping plate structure, including a front clamping plate 221 and two side clamping plates 222.

[0101] The clamps can be metal clamps, plastic clamps, etc., and can be selected according to actual needs. Specifically, the double-sided clamps 222 are installed on both sides of the battery cell 6, and the front clamp 221 is set at one end of the double-sided clamps 222 and abuts against the double-sided clamps 222. In actual application, the front clamp 221 is provided with a positioning pin, and one end of the double-sided clamps 222 is formed with a positioning hole. By inserting the positioning pin of the front clamp 221 into the positioning hole of the double-sided clamps 222, the connection between the front clamp 221 and the double-sided clamps 222 is realized.

[0102] It should be noted that the connection between the front clamping plate 221 and the two side clamping plates 222 can be achieved by setting positioning holes on the front clamping plate 221 and setting positioning pins on one end of the two side clamping plates 222. Other connection methods can also be used, such as screw connection, bonding, etc. The specific method can be selected according to actual needs, as long as the stable connection between the front clamping plate 221 and the two side clamping plates 222 is ensured. No limitation is made here.

[0103] In practical applications, the front clamping plate 221 and the two side clamping plates 222 are of the same height and are all less than the height of the battery cell 6. The length of the front clamping plate 221 is greater than the width of the battery cell 6, and the length of the two side clamping plates 222 is equal to the length of the battery cell 6. The positioning part formed by the three clamping plates fixes the battery cell 6. The accurate positioning of the battery cell 6 is achieved through the three clamping plate structure. The front clamping plate 221 blocks the forward movement of the battery cell 6, and the two side clamping plates clamp the battery cell 6, ensuring the positioning accuracy of the flattening part 23 when pressing the composite film layer against the inner wall of the injection port 61.

[0104] Step S30, film application process.

[0105] After the adhesive film cutting mechanism 1 cuts the required length of adhesive film, the adhesive film gripper 21 transports the first adhesive film to above the liquid injection port 61 of the battery cell 6 and performs the film application process longitudinally. The main body of the first adhesive film covers the top surface of the battery cell 6, and the adhesive film located on the side of the battery cell 6 is rotated and bent by the adhesive film gripper 21 to form the first clamping part 31, thus obtaining the first adhesive film layer 3. The above process is repeated to attach the second adhesive film layer 4 and the third adhesive film layer 5 to the liquid injection port 61, thus obtaining the second adhesive film layer 4 and the third adhesive film layer 5. The raised length H of the first clamping part 31, the second clamping part 41, and the third clamping part 51 formed by the first, second, and third adhesive films increases sequentially. In this embodiment, adhesive can be provided on one side of the adhesive film, which can better and more tightly connect the first adhesive film layer 3, the second adhesive film layer 4, and the third adhesive film layer 5.

[0106] The protective device 2 also includes a flattening component 23, which is used to press the composite film layer against the inner wall of the injection port 61. Figure 3 This is a schematic diagram of the structure of the flattening component provided in Embodiment 1 of this application, as shown below. Figure 3 As shown, the flattening component 23 includes a main body 231 and a piercing part 232 disposed on the main body 231.

[0107] The main body 231 has a frustum-shaped structure, but it can also be of other shapes as long as it matches the shape of the injection port 61. No limitation is made here. One end of the main body 231 extends to form a connecting rod, which can be connected to a rotating mechanism to drive the main body 231 to rotate. Furthermore, the outer surface of the main body 231 is a flat surface, which is press-fitted with the injection port 61 to ensure the adhesive film adheres tightly to the inner wall of the injection port.

[0108] The puncture part located at the other end of the main body 231 is a pointed structure, and the pointed tip can be used to puncture the film covering the injection port.

[0109] In practical applications, Figure 4 A schematic diagram of the composite membrane layer provided in this application is shown below. Figure 4As shown, after the first adhesive film, the second adhesive film, and the third adhesive film are attached to the injection port 61, the puncture part 232 can puncture the first adhesive film layer 3, the second adhesive film layer 4, and the third adhesive film layer 5 formed by the first adhesive film, the second adhesive film, and the third adhesive film. At the same time, the flattening part 23 can rotate at high speed to press the first adhesive film layer 3, the second adhesive film layer 4, and the third adhesive film layer 5 against the inner wall of the injection port 61. At this time, the first adhesive film layer 3 is tightly attached to the inner wall of the injection port 61.

[0110] It should be noted that the high-speed rotation of the kneading piece 23 can be achieved by a rotor or flywheel, or other types of devices, which are not limited here.

[0111] Step S40, the film removal process.

[0112] After the first liquid injection process is completed, the adhesive film clamps 21 clamp the third clamping part 51 of the third adhesive film layer 5 and peel off the third adhesive film layer 5 longitudinally; after the negative pressure formation process is completed, the adhesive film clamps 21 clamp the second clamping part 41 of the second adhesive film layer 4 and peel off the second adhesive film layer 4 longitudinally; after the second liquid injection process is completed, the adhesive film clamps 21 clamp the first clamping part 31 of the first adhesive film layer 3 and peel off the first adhesive film layer 3 longitudinally.

[0113] This application proposes a method to avoid residual crystallization in the electrolyte, which minimizes the problem of electrolyte contamination of the battery cell 6 and effectively solves the adverse effects of electrolyte crystallization on the compaction of the injection port 61 and the welding of the sealing pins after injection. Furthermore, this application is carried out without changing the original production process and equipment, and can significantly improve production efficiency while ensuring the performance of the battery cell 6.

[0114] Example 2:

[0115] This application proposes a method to prevent residual electrolyte crystallization, which protects the electrolyte inlet 61 area of ​​the battery cell 6 from contamination by residual electrolyte. Before each electrolyte injection process, three layers of adhesive film are applied to the electrolyte inlet 61 of the battery cell 6. Simultaneously, a smoothing component 23 embedded in the electrolyte inlet 61 smooths the adhesive film layers within the hole, ensuring they adhere to the inner wall of the electrolyte inlet 61. After each electrolyte injection process, the outermost third adhesive film is removed to eliminate residual electrolyte around the electrolyte inlet 61. This prevents the formation of crystallized electrolyte around the electrolyte inlet 61 after high-temperature settling, thus ensuring the smooth operation of the negative pressure formation process and avoiding low production efficiency caused by downtime for wiping away crystallized electrolyte.

[0116] Furthermore, the remaining two layers of adhesive film are peeled off after the negative pressure formation process and the secondary electrolyte injection process, respectively. This minimizes the problem of electrolyte contamination of the battery cell 6 and effectively solves the adverse effects of electrolyte crystallization on the compaction of the injection port 61 and the welding of the sealing nails after the electrolyte injection is completed. At the same time, this application is carried out without changing the original production process and equipment, and can greatly improve production efficiency while ensuring the performance of the battery cell 6.

[0117] Specifically, methods to avoid residual crystallization in the electrolyte can be roughly divided into four steps:

[0118] Step S10, film cutting process;

[0119] Step S20, cell 6 positioning process;

[0120] Step S30, film application process;

[0121] Step S40, the film removal process.

[0122] Figure 5 This is a schematic diagram of the protective device provided in Embodiment 2 of this application, as shown below. Figure 5 As shown, the above steps are achieved through the protective device 2. The following describes this solution in detail with reference to specific embodiments:

[0123] The difference from Example 1 is:

[0124] Step S20, cell 6 positioning process.

[0125] In step S20, the positioning of the battery cell 6 is achieved by the vision inspection device 24 (Charge-coupled Device, CCD).

[0126] The visual inspection device 24 converts the captured target into an image signal and transmits it to a dedicated image processing system. Based on pixel distribution and information such as brightness and color, the signal is converted into a digital signal. The image system performs various calculations on these signals to extract the target's features, and then controls the on-site equipment based on the judgment results.

[0127] For example, the visual inspection device 24 includes:

[0128] Sensor: Used to determine the position and state of the detected battery cell 6, and transmit information to the image sensor for acquisition.

[0129] Light source: determines the quality of the imaging effect. Visual light sources include at least one of LED, high-frequency fluorescence, and fiber optic halogen.

[0130] Visual camera / lens: Imaging device of visual inspection device 24.

[0131] Image acquisition card: Used to transmit images of the battery cells captured by the vision camera to the computer, and to convert the analog or digital signals from the camera into corresponding image data streams for analysis.

[0132] PC platform: Processes the transmitted visual images of the battery cells and performs most of the logical operations.

[0133] Vision processing software: Machine vision software is used to process the input image data and then calculate the results, such as the coordinate position of cell 6.

[0134] Control unit: After the vision software completes the cell image analysis, it then communicates with external units to control the production process, such as transporting cell 6 to a preset position.

[0135] In practical applications, the battery cell 6 is converted into a battery cell image signal by sensors and vision cameras. Then, the image acquisition card sends the battery cell image signal to the PC platform. Based on the pixel distribution, brightness, color and other information of the battery cell image signal, the battery cell image signal is converted into a battery cell digital signal. The vision processing software performs various operations on these battery cell digital signals to extract the position features of the battery cell 6. Then, according to the preset position conditions, the control unit controls the device to precisely move the battery cell 6 to the preset position.

[0136] Except for the steps specifically described above, the remaining steps are the same as in Example 1, and will not be repeated here.

[0137] Example 3:

[0138] This application proposes a method to prevent residual electrolyte crystallization, which protects the electrolyte inlet 61 area of ​​the battery cell 6 from contamination by residual electrolyte. Before each electrolyte injection process, three layers of adhesive film are applied to the electrolyte inlet 61 of the battery cell 6. Simultaneously, a smoothing component 23 embedded in the electrolyte inlet 61 smooths the adhesive film layers within the hole, ensuring they adhere to the inner wall of the electrolyte inlet 61. After each electrolyte injection process, the outermost third adhesive film is removed to eliminate residual electrolyte around the electrolyte inlet 61. This prevents the formation of crystallized electrolyte around the electrolyte inlet 61 after high-temperature settling, thus ensuring the smooth operation of the negative pressure formation process and avoiding low production efficiency caused by downtime for wiping away crystallized electrolyte.

[0139] Furthermore, the remaining two layers of adhesive film are peeled off after the negative pressure formation process and the secondary electrolyte injection process, respectively. This minimizes the problem of electrolyte contamination of the battery cell 6 and effectively solves the adverse effects of electrolyte crystallization on the compaction of the injection port 61 and the welding of the sealing nails after the electrolyte injection is completed. At the same time, this application is carried out without changing the original production process and equipment, and can greatly improve production efficiency while ensuring the performance of the battery cell 6.

[0140] Specifically, methods to avoid residual crystallization in the electrolyte can be roughly divided into four steps:

[0141] Step S10, film cutting process;

[0142] Step S20, cell 6 positioning process;

[0143] Step S30, film application process;

[0144] Step S40, the film removal process.

[0145] The above steps are achieved through the film cutting mechanism 1 and the protective device 2. The following describes this solution in detail with reference to specific embodiments:

[0146] The difference from Example 1 is:

[0147] Step S30, film application process.

[0148] After the adhesive film cutting mechanism 1 cuts the required length of adhesive film, the adhesive film gripper 21 transports the first adhesive film to above the liquid injection port 61 of the battery cell 6 and performs the film application process longitudinally. The main body of the first adhesive film covers the top surface of the battery cell 6, and the adhesive film located on the side of the battery cell 6 is rotated and bent by the adhesive film gripper 21 to form the first clamping part 31, thus obtaining the first adhesive film layer 3. The above process is repeated to attach the second adhesive film layer 4 and the third adhesive film layer 5 to the liquid injection port 61, thus obtaining the second adhesive film layer 4 and the third adhesive film layer 5. The raised length H of the first clamping part 31, the second clamping part 41, and the third clamping part 51 formed by the first, second, and third adhesive films increases sequentially. In this embodiment, adhesive can be provided on one side of the adhesive film, which can better and more tightly connect the first adhesive film layer 3, the second adhesive film layer 4, and the third adhesive film layer 5.

[0149] The protective device 2 also includes a flattening part 23 with threads 233 on its surface. Figure 6 This is a schematic diagram of the structure of the flattening component provided in Embodiment 3 of this application, as shown below. Figure 6As shown, the kneading component 23 includes a main body 231 and a piercing part 232 disposed on the main body 231. The main body 231 has a frustum-shaped structure, but it can also be an injection port 61 of other shapes, as long as it is consistent with the shape of the injection port 61. There is no limitation here. The main body 231 is provided with a kneading surface, and the thread 233 is formed on the kneading surface. The kneading surface is interference-fitted with the injection port 61. In actual application, after the first adhesive film, the second adhesive film and the third adhesive film are attached to the injection port 61, the piercing part 232 can pierce the first adhesive film layer 3, the second adhesive film layer 4 and the third adhesive film layer 5 formed by the first adhesive film, the second adhesive film and the third adhesive film. At the same time, the kneading part 23 can rotate at high speed to press the first adhesive film layer 3, the second adhesive film layer 4 and the third adhesive film layer 5 against the inner wall of the injection port 61. At this time, the first adhesive film layer 3 is tightly attached to the inner wall of the injection port 61. During this process, the thread 233 of the kneading surface can better adhere the adhesive film to the inner wall of the injection port 61 and prevent the adhesive film from forming air bubbles on the inner wall of the injection port 61.

[0150] It should be noted that the high-speed rotation of the kneading piece 23 can be achieved by a rotor or flywheel, or other types of devices, which are not limited here.

[0151] Except for the steps specifically described above, the remaining steps are the same as in Example 1, and will not be repeated here.

[0152] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A method for avoiding residual crystallization in electrolyte, characterized in that, At least the following steps are included: Before a liquid injection process, the main body of the first adhesive film is covered on the top surface of the battery cell. The first adhesive film located on the side of the battery cell is bent and twisted by the adhesive film clamp to form a first clamping part, and a first adhesive film layer is obtained. The above process is repeated to obtain a second adhesive film layer and a second clamping part formed by the second adhesive film layer, and a third adhesive film layer and a third clamping part formed by the third adhesive film layer. The first adhesive film layer, the second adhesive film layer and the third adhesive film layer are stacked to form a composite adhesive film layer. The piercing part of the flattening component is used to pierce the third adhesive film layer, the second adhesive film layer and the first adhesive film layer in sequence, and the flattening component is rotated to press the first adhesive film layer, the second adhesive film layer and the third adhesive film layer against the inner wall of the injection port, so that the first adhesive film layer adheres tightly to the inner wall of the injection port. After one injection process, the third adhesive film layer is removed; After the negative pressure formation process, the second adhesive film layer is removed; After the second injection process, the first adhesive film layer is removed.

2. The method according to claim 1, characterized in that, The first adhesive film layer includes a first clamping portion, the second adhesive film layer includes a second clamping portion, and the third adhesive film layer includes a third clamping portion, with the length H of the first clamping portion, the second clamping portion, and the third clamping portion increasing sequentially.

3. The method according to claim 1, characterized in that, The widths of the first adhesive layer, the second adhesive layer, and the third adhesive layer are at least 1.5 times the outer diameter of the injection port.

4. The method according to claim 1, characterized in that, The adhesive film is cut by an adhesive film cutting mechanism.

5. The method according to any one of claims 1-4, characterized in that, The battery cell is positioned by the positioning component of the protective device, and the adhesive film cut by the adhesive film cutting mechanism is covered by the adhesive film clamps to the injection port. The flattening component presses the adhesive film in and adheres it tightly to the inner wall of the injection port.

6. A protective device for preventing residual crystallization of electrolyte, used in the method for preventing residual crystallization of electrolyte as described in any one of claims 1-5, characterized in that, The protective device includes adhesive film grippers, which are used to grip the adhesive film and perform film application and peeling processes; and A smoothing component, comprising a main body and a puncture portion, wherein the main body is provided with a smoothing surface, the main body cooperates with the injection port, the main body uses the smoothing surface to adhere the adhesive film to the inner wall of the injection port, and the puncture portion punctures the adhesive film layer formed by the film application process.

7. The apparatus according to claim 6, characterized in that, The main body has a threaded surface, which is used to further fit the adhesive film to the inner wall of the injection port.

8. The apparatus according to claim 6, characterized in that, The protective device is also equipped with a positioning element, which is used to position the battery cell.

9. The apparatus according to claim 6, characterized in that, The protective device also includes a film cutting mechanism, which includes a first clamping member and a second clamping member, wherein the first clamping member is movable relative to the second clamping member.

10. The apparatus according to any one of claims 6-9, characterized in that, The film cutting mechanism further includes a cutter. After the first clamping member moves to the required length of the film layer, the cutter cuts the film, and the film gripper delivers the film to the injection port.

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