Cylindrical battery formation device and formation method thereof

Abstract

The application discloses a cylindrical battery formation device and a formation method thereof, and belongs to the technical field of lithium ion battery manufacturing, and is suitable for high-nickel positive electrode-silicon-carbon negative electrode cylindrical batteries. The device comprises a formation special tray, a sealing rubber nail with an air chamber, a pressing plate with a limiting hole, and a formation probe assembly arranged on the same side. The rubber nail is provided with a profiling end face and a closed air chamber, the pressing plate applies uniform pressure to the rubber nail, and the probe adopts a layout of a middle negative electrode and an edge positive electrode. The formation method comprises the steps of injecting a plug rubber nail, assembling a tray, pressing, forming, disassembling the pressing plate, pulling the rubber nail, supplementing liquid and sealing, and part of gas is slowly stored in the rubber nail air chamber during formation. The application can solve the problems of high product safety risk caused by excessively high internal pressure during closed formation, high energy consumption and high production cost during open formation. The application is suitable for industrial production of 26, 32, 46 and 60 series cylindrical batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, and in particular to a cylindrical battery formation apparatus and formation method thereof. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage, and consumer electronics industries, the market demand for high-energy-density lithium-ion batteries continues to grow. Among them, battery systems composed of high-nickel cathodes (such as NCM811 and NCM911) and silicon-carbon anodes have become the core technology route for next-generation power batteries due to their advantages of high theoretical capacity and long driving range. Cylindrical batteries, due to their compact structure, easy consistency control, and good heat dissipation performance, are widely used in the large-scale production of this system, and large cylindrical batteries such as 26, 32, 46, and 60 series have become the mainstream direction of industry development.

[0003] Formation is a core process in the manufacturing of lithium-ion batteries. It involves forming a solid electrolyte interphase (SEI) film on the surface of the negative electrode during the first charge, which determines the battery's initial coulombic efficiency, cycle life, safety, and consistency.

[0004] However, the high-nickel cathode-silicon-carbon anode system generates a large amount of CO during the formation process. , The gas produced is 2-3 times that of traditional graphite anode systems, posing a severe challenge to existing formation processes. Currently, the mainstream cylindrical battery formation processes in the industry are mainly divided into three categories: closed-loop formation, open-loop formation, and intermittent degassing formation, but all of them have insurmountable technical defects.

[0005] A search revealed a Chinese invention patent with publication number CN114464894A, which discloses a method to improve the safety of cylindrical lithium-ion batteries. The method involves improving battery safety through pressurized formation. However, it only uses a shell explosion-proof valve for one-time pressure relief, which cannot achieve dynamic pressure control during the formation process. The internal pressure fluctuates greatly, and it still cannot solve the problems of poor SEI film formation quality and low batch consistency.

[0006] Chinese invention patent CN115064825A discloses a cap structure and a cylindrical battery. The battery cap has a venting structure, which can release gas during the formation process. However, this structure still falls under the category of open formation, which cannot avoid the problems of electrolyte absorbing water and evaporation. Moreover, the cap structure is complex, which increases the manufacturing cost of the battery.

[0007] Chinese invention patent CN106129505A discloses a lithium-ion battery formation method. The intermittent venting formation scheme of the soft-pack battery in this invention involves puncturing the air bag and venting the gas. However, this scheme is only applicable to soft-pack batteries and cannot be adapted to the structural characteristics of cylindrical batteries. Moreover, the venting process can easily lead to excessive loss of electrolyte.

[0008] Therefore, this application proposes a cylindrical battery formation device and method that can achieve dynamic buffering and step-by-step depressurization of formation gas, ensure uniform and dense SEI film, reduce energy consumption, and be suitable for industrial mass production. Summary of the Invention

[0009] One objective of this invention is to provide a cylindrical battery formation apparatus and method. This invention can effectively solve the safety hazards of large gas production and excessive internal pressure during the formation of high-nickel cathode-silicon-carbon anode cylindrical batteries, form a dense and uniform SEI film to improve battery cycle performance, significantly improve battery batch consistency and production yield, and reduce formation energy consumption and production costs. It is perfectly suited for the industrial mass production of 26, 32, 46, and 60 series cylindrical batteries.

[0010] A cylindrical battery formation apparatus according to an embodiment of the present invention includes a formation-specific tray for supporting battery cells, adhesive pins for sealing the electrolyte inlets of the battery cells, a pressure plate for fixing the adhesive pins, and a formation probe assembly for electrically connecting to the battery cell terminals.

[0011] The end face of the glue nail is designed to mimic the outline of the battery cell's liquid injection port to form a glue nail contour end face, and the inside of the glue nail is provided with a closed glue nail gas chamber for buffering the gas generated during formation.

[0012] The pressure plate is provided with limiting holes corresponding to the rubber nails. The upper part of the rubber nail is embedded in the corresponding limiting hole. The pressure plate can apply a uniform pressure of 0.2–0.3 MPa to the rubber nail.

[0013] The entire formation probe assembly is located on the same side of the cell, including a negative electrode probe in the middle and a positive electrode probe surrounding the edge.

[0014] A method for forming a cylindrical battery assembly includes the following steps:

[0015] S1: After the cell is injected with electrolyte, a rubber plug is inserted. After the cell has completed one injection, in a dry environment with a room temperature of 20–25℃ and a dew point value ≤-40℃, the rubber plug with its own air chamber is slowly inserted into the cell's injection port, ensuring that the conformal end face of the rubber plug fits tightly against the injection port without gaps or deviation; the amount of electrolyte injected in one injection is 80%–85% of the electrolyte volume corresponding to the cell's rated capacity.

[0016] S2: Cell assembly tray. Neatly place the cells with the glued nails into the special forming tray. The spacing between the cells should be controlled at 5-8mm.

[0017] S3: Apply pressure. Align the pressure plate with the corresponding limiting holes for each glue nail with the glue nail on the special tray for chemical processing, so that the upper part of each glue nail is embedded in the corresponding limiting hole. Apply a uniform pressure of 0.2–0.3MPa to the pressure plate and fix the relative position of the pressure plate and the special tray for chemical processing.

[0018] S4: Formation. The formation tray containing the battery cell and pressure plate is fed into the formation equipment. The position of the formation probes is adjusted so that the middle negative probe contacts the negative terminal of the battery cell and the edge positive probe contacts the positive terminal of the battery cell. The contact pressure between the probe and the terminal is controlled at 0.1–0.2 MPa. The formation equipment is started and charged at a constant current of 0.05–0.5C in 3–4 stages for 7 hours at an ambient temperature of 35–45℃, gradually increasing the battery cell voltage to 4.2V.

[0019] S5: Remove the pressure plate. After the formation process is completed, transfer the formation-specific tray along with the pressure plate to the replenishment room. Remove the fastening structure of the pressure plate in a dry environment and take off the pressure plate.

[0020] S6: Disassembly and removal of adhesive pins. Remove the battery cells from the special tray to complete the disassembly. Use special equipment and tools to slowly remove the adhesive pins. Keep the battery cells vertical throughout the process of removing the adhesive pins. Immediately after removing the adhesive pins, transfer the battery cells to the liquid replenishment station.

[0021] S7: Replenishing and Sealing. Replenish the electrolyte with the same type as the first electrolyte injection into the electrolyte injection port of the cell after removing the glue pins. The replenishment amount is 15%–20% of the electrolyte amount corresponding to the rated capacity of the cell. After replenishment, immediately seal the cell.

[0022] Furthermore, the material of the adhesive nail is a polymer material that is resistant to electrolyte corrosion and has excellent elasticity, preferably fluororubber. The fluororubber can adapt to temperature changes of 25–60℃ and pressure fluctuations of 0–1.5MPa, and does not undergo side reactions with the electrolyte.

[0023] Furthermore, the gap between the inner diameter of the limiting hole of the pressure plate and the outer diameter of the upper part of the rubber nail is 0.2–0.6 mm; the pressure plate is fixedly connected to the chemical forming special tray by fastening bolts to ensure that the pressure applied to all rubber nails is uniform and consistent, and does not hinder the elastic deformation and pressure relief function of the rubber nail air chamber.

[0024] Furthermore, the formation-specific tray is made of aluminum alloy or engineering plastic material. The formation-specific tray is provided with a positioning groove that is adapted to the bottom of the cell. The bottom of the positioning groove of a single cell can withstand a pressure of not less than 0.5MPa, and the formation-specific tray can withstand a long-term formation working temperature of 35–45℃.

[0025] Furthermore, in step S4, when the formation process is carried out in three stages, the first stage is charged with a constant current of 0.05–0.1C to a cell voltage of 3.0V, the second stage is charged with a constant current of 0.1–0.3C to a cell voltage of 3.8V, and the third stage is charged with a constant current of 0.3–0.5C to a cell voltage of 4.2V. The total charging time for the three stages is 7 hours.

[0026] Furthermore, in step S4, after each charging stage is completed, the elastic deformation of the glue nail gas chamber is used to achieve a step-by-step depressurization, so that the formation gas buffered in the glue nail gas chamber is discharged in an orderly manner. During the depressurization process, the pressure of the pressure plate on the glue nail remains unchanged until all formation stages are completed.

[0027] Furthermore, in step S, the removal of adhesive pins, the removal speed of the special equipment tooling is controlled at 0.5–1 mm / s, the removal direction coincides with the axis of the battery cell's liquid injection port, and after the adhesive pins are removed, the battery cell stays at the liquid replenishment station for no more than a minute.

[0028] Furthermore, the processes of removing the glue pins, replenishing the liquid, and sealing in steps S6 and S7 are all carried out in a dry environment with a dew point value of ≤-40℃; the battery cell is kept vertical during the replenishment process, and the sealing operation is completed within 1 minute after the replenishment is completed.

[0029] Furthermore, the method is compatible with 26, 32, 46, and 60 series cylindrical batteries, and is especially suitable for high-energy-density cylindrical batteries with a high-nickel cathode-silicon-carbon anode system, wherein the high-nickel cathode includes NCM811 and NCM911, and the compatible cylindrical batteries have a rated capacity of ≥6Ah.

[0030] The beneficial effects of this invention are:

[0031] 1. In this invention, a special adhesive pin with a built-in gas chamber is used to plug the gas chamber, which can effectively buffer the gas generated during the formation process and prevent excessive internal pressure in the cell from affecting the SEI film formation. At the same time, it avoids problems such as shell bulging, leakage, and malfunction of the explosion-proof valve caused by a sudden increase in internal pressure during the formation process, thus solving the safety hazards of closed-cell formation. Combined with the pressure relief process, the gas can be discharged in an orderly manner, solving the problem of excessive internal pressure and improving safety. It is especially suitable for the high gas production characteristics of high-nickel cathode-silicon-carbon anode cylindrical batteries.

[0032] 2. In this invention, a uniform axial pressure of 0.2-0.3 MPa is applied to all the rubber nails by a pressure plate. Combined with the surface contact sealing structure of the conformal end face of the rubber nails, this ensures that the sealing effect and pressure relief characteristics of each cell are completely consistent, avoiding electrolyte leakage problems caused by open circuits. A probe arrangement of "a single negative electrode probe in the center and multiple positive electrode probes surrounding the edge" ensures a reasonable match between the positive and negative charging currents.

[0033] 3. In this invention, the formation process is achieved through sealing with rubber nails. Dew point control is only required during the liquid injection, nail insertion / removal, and liquid replenishment stages. The formation process only requires a relative humidity of ≤30%, significantly reducing overall energy consumption. The process steps are simple, eliminating the need for complex intermittent or vacuum venting equipment, thus reducing equipment investment. The rubber nails are made of fluororubber resistant to electrolyte corrosion, adaptable to temperature changes of 25-60℃ and pressure fluctuations of 0-1.5MPa, maintaining good sealing performance even after multiple reuses, further reducing consumable costs. Furthermore, this method can be directly adapted to existing production lines for the entire range of cylindrical batteries (26, 32, 46, 60, etc.) without large-scale equipment modifications, facilitating rapid and widespread application. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of a cylindrical battery formation device with adhesive nails attached to the battery cell, as proposed in this invention.

[0036] Figure 2 This is a cross-sectional view of the adhesive pins in a cylindrical battery formation apparatus proposed in this invention;

[0037] Figure 3 This is a diagram of a cylindrical battery formation apparatus proposed in this invention.

[0038] Figure 4 This is a schematic diagram of the pressurization structure of a cylindrical battery formation device proposed in this invention;

[0039] Figure 5 This is a schematic diagram of the pressure plate limiting hole of a cylindrical battery formation device proposed in this invention;

[0040] Figure 6 This is a schematic diagram of the formation probe structure of a cylindrical battery formation device proposed in this invention;

[0041] Figure 7 This is a flowchart of a cylindrical battery formation method proposed in this invention.

[0042] In the diagram: 1. Battery cell; 2. Glue pin; 21. Glue pin air chamber; 22. Glue pin contoured end face; 3. Formation special tray; 4. Pressure plate; 41. Limiting hole; 5. Negative electrode probe; 6. Positive electrode probe. Detailed Implementation

[0043] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0044] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0045] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The present invention discloses a cylindrical battery formation apparatus, including a formation-specific tray 3 for supporting a battery cell 1, a glue pin 2 for sealing the liquid injection port of the battery cell 1, a pressure plate 4 for fixing the glue pin 2, and a formation probe assembly for electrically connecting to the terminal of the battery cell 1.

[0048] like Figure 1 , Figure 2 As shown, the rubber nail 2 is an integrated elastic sealing structure, which is a stepped cylindrical shape. Its lower end face is designed to conform to the inner contour of the liquid injection port of the battery cell 1 to form a rubber nail conforming end face 22. The curvature and diameter of the conforming end face 22 are completely matched with the inner wall of the liquid injection port of the battery cell 1. After being plugged, it can form a surface contact seal with the liquid injection port, effectively preventing electrolyte leakage during the formation process.

[0049] The rubber nail 2 has a closed hollow rubber nail air chamber 21 inside. The volume of the rubber nail air chamber 21 is designed according to the gas production of the corresponding cylindrical battery model during formation, and can accommodate CO and other gases generated during the formation process. , Gas. The top of the gas chamber 21 is an elastic structure. When the internal gas pressure increases, it will deform appropriately outward to buffer the gas and prevent a sudden increase in the internal pressure of the battery cell 1.

[0050] The material of the adhesive nail 2 is a high-molecular material that is resistant to electrolyte corrosion and has excellent elasticity, preferably fluororubber. Fluororubber has excellent resistance to organic solvent corrosion and will not undergo any side reactions with carbonate electrolytes commonly used in high-nickel-silicon-carbon systems that would affect battery performance. At the same time, its elastic modulus is moderate, which can adapt to formation temperature changes of 25–60℃ and internal pressure fluctuations of 0–1.5MPa. It can still maintain good sealing performance after multiple elastic deformations, and can be reused multiple times, further reducing production costs.

[0051] like Figure 3 As shown, the special pallet 3 is a rectangular plate structure made of aluminum alloy or high-strength engineering plastic. The aluminum alloy pallet has the advantages of good thermal conductivity, high strength, and resistance to deformation, making it suitable for large-scale continuous production; the engineering plastic pallet has the advantages of good insulation, light weight, and low cost, making it suitable for mass production.

[0052] The upper surface of the formation-specific tray 3 is evenly distributed with multiple cylindrical positioning grooves that conform to the bottom shape of the battery cell 1. The depth of the positioning grooves is 1 / 10–1 / 8 of the height of the battery cell 1, which can accurately position the battery cell 1 and prevent it from tipping over during handling and formation. The bottom of the positioning groove of a single battery cell 1 can withstand a pressure of not less than 0.5MPa, and the entire tray can withstand a long-term formation working temperature of 35–45℃ without thermal deformation.

[0053] The center distance between adjacent positioning slots is the diameter of cell 1 + 5–8 mm. That is, after cell 1 is placed in the positioning slot, the distance between adjacent cells 1 is 5–8 mm. This distance can ensure smooth airflow and uniform heat dissipation during the formation process, and avoid differences in battery performance due to local overheating.

[0054] like Figure 4 , Figure 5 As shown, the pressure plate 4 is a rectangular plate structure that matches the size of the chemical forming special tray 3. It is made of high-strength engineering plastic or alloy material and has sufficient rigidity so that it will not bend or deform after being pressurized.

[0055] The lower surface of the pressure plate 4 is provided with a limiting hole 41, which is a cylindrical through hole with a gap of 0.2–0.6 mm between its inner diameter and the upper outer diameter of the glue nail 2. This gap design can not only achieve precise radial positioning of the glue nail 2 to prevent the glue nail 2 from shifting, tilting or even falling off due to internal pressure during the formation process, but also reserve sufficient axial space for the elastic deformation of the top of the glue nail air chamber 21.

[0056] The pressure plate 4 is equipped with fastening holes and is fixedly connected to the formation tray 3 by fastening bolts or clips, which can apply a uniform axial pressure of 0.2–0.3 MPa to all the glue nails 2. This pressure ensures that the conformal end face 22 of the glue nail and the electrolyte injection port of the cell 1 always remain in tight contact, and no electrolyte leakage will occur even when the internal pressure fluctuates during the formation process; at the same time, the uniform pressure ensures that the sealing effect of all cells 1 is consistent, thereby ensuring the consistency of the formation process.

[0057] like Figure 6 As shown, the formation probe assembly is entirely located on the same side of the electrode post of the battery cell 1, and is electrically connected to the electrode post of the battery cell 1 using a top-mounted contact method. The probe assembly includes a negative electrode probe 5 located in the middle and multiple positive electrode probes 6 surrounding the edge. In this embodiment, there are 3 positive electrode probes 6, which are evenly distributed around the negative electrode probe 5.

[0058] This "central negative electrode, edge positive electrode" arrangement allows the current to be evenly distributed on the electrode post of cell 1, avoiding excessive local polarization and high temperature rise caused by current concentration, and is conducive to the formation of a uniform and dense SEI film. The negative electrode probe 5 and the positive electrode probe 6 are equipped with a spring structure to ensure that the contact pressure between the probe and the electrode post is stable at 0.1–0.2 MPa, ensuring good conductivity.

[0059] like Figure 7 As shown, the cylindrical battery formation method using the above-mentioned formation apparatus is carried out in the following steps:

[0060] S1: After filling cell 1 with electrolyte, plug with rubber nail 2.

[0061] After the battery cell 1 completes the winding, assembly, baking and dehydration processes, it is transferred to the liquid injection workshop for a liquid injection operation.

[0062] The initial electrolyte injection volume is 80%–85% of the electrolyte volume corresponding to the rated capacity of cell 1, with 15%–20% of the electrolyte volume reserved for subsequent replenishment. At the same time, some internal space is reserved to accommodate the gas generated during the formation process, so as to avoid excessive internal pressure due to insufficient space.

[0063] After the electrolyte filling is completed, in a dry environment with a room temperature of 20–25℃ and a dew point value ≤-40℃, use a special tool to slowly insert the rubber nail 2 into the electrolyte filling port of the battery cell 1. During the insertion process, keep the rubber nail 2 coaxial with the electrolyte filling port and ensure that the conformal end face 22 of the rubber nail is completely in contact with the inner wall of the electrolyte filling port without gaps or offset. After the insertion is completed, check whether the rubber nail 2 of all battery cells 1 is installed in place and whether there is any looseness or tilting.

[0064] S2: 1 set of battery cells

[0065] Place the battery cells 1 with the glue nails 2 inserted one by one into the positioning slots of the special forming tray 3, and adjust the orientation of the battery cells 1 so that the terminals of all the battery cells 1 face upwards in the same direction.

[0066] It is important to handle the battery cells with care during placement to avoid collisions that could damage the internal structure. Also, ensure that the spacing between adjacent battery cells is 5–8 mm to guarantee even heat dissipation.

[0067] S3: Pressurization

[0068] Place the pressure plate 4 horizontally above the special forming tray 3, and adjust the position of the pressure plate 4 so that all the limiting holes 41 on the pressure plate 4 are aligned with the glue nails 2 on the battery cell 1 below.

[0069] Then slowly lower the pressure plate 4 so that the upper part of each glue nail 2 is precisely embedded in the corresponding limiting hole 41.

[0070] Tighten the fastening bolts at the four corners of the pressure plate 4 in sequence, and control the tightening torque with a torque wrench so that the pressure plate 4 applies a uniform axial pressure of 0.2–0.3 MPa to all the rubber nails 2.

[0071] During the tightening process, a diagonal tightening method is used to avoid uneven pressure distribution caused by tilting of the pressure plate 4.

[0072] After tightening, check whether all the glue nails 2 are embedded in the limiting holes 41 and whether the pressure plate 4 is parallel to the chemical formation special tray 3.

[0073] S4: Transformation

[0074] The formation tray 3 containing the battery cell 1 and the pressure plate 4 is sent into the formation position of the formation equipment. The height of the formation probe assembly is adjusted so that the negative electrode probe 5 in the middle is in close contact with the negative electrode post of the battery cell 1, and the positive electrode probe 6 on the edge is in close contact with the positive electrode post of the battery cell 1.

[0075] The contact pressure between the control probe and the electrode post is 0.1–0.2 MPa to ensure good contact and stable conductivity.

[0076] Start the formation equipment and charge the cell at a constant current of 0.05–0.5C in 3–4 stages for 7 hours in a constant temperature environment of 35–45℃, gradually increasing the voltage of cell 1 to 4.2V.

[0077] During the formation process, the gas generated by the electrochemical reaction inside the battery cell 1 enters the glue nail gas chamber 21 through the liquid injection port for buffering;

[0078] During the process, the pressure of the pressure plate 4 on the glue nail 2 remains constant until all formation stages are completed.

[0079] S5: Remove pressure plate 4

[0080] After the formation process is complete, the formation tray 3, together with the pressure plate 4, is removed from the formation equipment and transferred to the replenishment room.

[0081] In a dry environment with a dew point of ≤-40℃, loosen the fastening bolts of the pressure plate 4 one by one in a diagonal manner, and then remove the pressure plate 4 smoothly.

[0082] Avoid touching the glue pin 2 during operation to prevent the glue pin 2 from loosening and causing electrolyte leakage or premature discharge of residual gas.

[0083] S6: Disassembling the plate and removing the glue nails 2

[0084] The battery cells 1 are removed one by one from the special tray 3 to complete the disassembly and transferred to the glue removal station.

[0085] The glue pin 2 is slowly pulled out using a special automated equipment tooling. The pulling speed is controlled at 0.5–1 mm / s, and the pulling direction is strictly aligned with the axis of the liquid injection port of the battery cell 1.

[0086] During the process of removing the glue nail 2, the battery cell 1 is kept vertical to avoid the electrolyte overflowing due to negative pressure caused by tilting or excessive pulling speed.

[0087] Secondly, after removing the adhesive pin 2, immediately transfer the battery cell 1 to the electrolyte replenishment station to prevent the electrolyte from absorbing water or evaporating due to prolonged exposure to air, which would affect battery performance.

[0088] S7: Liquid replenishment and sealing

[0089] A high-precision electrolyte injection machine is used to replenish the electrolyte inlet of the cell 1 after the glue pin 2 has been removed. The replenishment amount is 15%–20% of the electrolyte amount corresponding to the rated capacity of the cell 1, to ensure that the electrolyte amount inside the cell 1 is sufficient to meet the requirements of the battery cycle life.

[0090] Keep cell 1 vertical during electrolyte replenishment to prevent electrolyte overflow.

[0091] Within one minute of completing the liquid replenishment, cell 1 is sealed using laser welding or mechanical sealing to complete the entire formation process.

[0092] The above-mentioned processes of removing the glue pins, replenishing the electrolyte, and sealing are all carried out in a dry environment with a dew point value of ≤-40℃. The moisture content in the environment is strictly controlled to avoid the electrolyte absorbing water, which would increase the battery's self-discharge and shorten its cycle life.

[0093] Example 1

[0094] This embodiment focuses on the 26700 model high-nickel NCM811 positive electrode-silicon-carbon negative electrode cylindrical battery, employing the formation method of the present invention. The specific steps are as follows:

[0095] S1. Inserting rubber nails after cell electrolyte filling: After the 26700 cell completes one electrolyte filling, the filling volume is 80% of the electrolyte volume corresponding to the cell's rated capacity of 6Ah. Under an environment of room temperature of 23℃ and dew point of -40℃, insert the rubber nails into the cell's electrolyte filling port, ensuring that the conformal end face of the rubber nails fits tightly against the filling port.

[0096] S2. Cell assembly: Arrange the cells with the glued nails in a neat place in the formation tray, with a spacing of 8mm between the cells.

[0097] S3. Apply pressure: Align the pressure plate with the rubber nail, so that the rubber nail is embedded in the gap of the limiting hole by 0.5mm, and apply a pressure of 0.25MPa by tightening to fix the pressure plate and the tray.

[0098] S4. Formation: The tray is fed into the formation equipment, so that the middle negative electrode probe contacts the negative electrode post of the cell and the edge positive electrode probe contacts the positive electrode post of the cell. The contact pressure is 0.12MPa, the formation current is 0.05-0.5C, and the total formation time is 7h. It is carried out in 3 stages, gradually increasing the voltage to 4.2V.

[0099] S5. Depressurize and remove the pressure plate: After the formation is complete, transfer the tray to the replenishment room, remove the pressure plate, and avoid touching the glue pins.

[0100] S6. Removing the tray and removing the adhesive pins: Remove the battery cells from the tray and slowly remove the adhesive pins using a special tooling, keeping the battery cells upright to prevent electrolyte leakage.

[0101] S7. Replenishing electrolyte and sealing: Replenish electrolyte to the cell's electrolyte inlet, with the replenishment amount being 20% ​​of the rated electrolyte volume. After replenishment, seal the inlet.

[0102] The 26700 battery formed in this embodiment has a voltage difference of ≤2.5mV in the 3.2–3.4V range, a formation scrap rate of 0.8%, a capacity retention rate of 94.2% after 350 cycles, and an overall production cost that is 18% lower than that of open-cell formation.

[0103] Example 2

[0104] This embodiment targets a 26120 model high-nickel NCM911 positive electrode and silicon-carbon negative electrode cylindrical battery. Cell 1 has a rated capacity of 14.5Ah. The formation apparatus and formation method of this invention are used, and the specific steps are as follows:

[0105] S1 Plug 2: After cell 1 completes one electrolyte injection, the injection volume is 85% of the rated electrolyte volume; in a dry environment with room temperature of 25℃ and dew point of -40℃, plug the plug 2 into the electrolyte injection port of cell 1 to ensure a reliable seal.

[0106] S2 tray: Place the battery cell 1 with the glue nails 2 in a high-strength engineering plastic special forming tray 3, with a spacing of 8mm between the battery cells 1.

[0107] S3 Pressurization: Install the pressure plate 4, insert the rubber nail 2 into the limiting hole 41 with a gap of 0.5mm, apply a uniform pressure of 0.3MPa, and fix the pressure plate 4 and the chemical forming special tray 3.

[0108] S4 Formation: The tray is fed into the formation equipment, so that the middle negative electrode probe contacts the negative electrode post of the cell, and the edge positive electrode probe contacts the positive electrode post of the cell. The contact pressure is 0.12 MPa, the formation current is 0.05-0.5 C, and the total formation time is 7 hours. It is carried out in 3 stages, and the voltage is gradually increased to 4.2 V.

[0109] S5 Remove pressure plate 4: After the formation is completed, transfer the tray to the replenishment room and remove pressure plate 4.

[0110] S6 Disassembly and removal of adhesive pin 2: Take out cell 1, pull out adhesive pin 2 vertically at a speed of 1mm / s, place it in the liquid replenishment station, and leave it for 2 minutes.

[0111] S7 electrolyte replenishment and sealing: Replenish electrolyte to 15% of the rated electrolyte volume, and seal the opening after replenishment.

[0112] The 26120 battery prepared in this embodiment has a voltage difference of ≤3mV in the 3.2–3.4V range, a formation failure rate of 0.7%, and a capacity retention rate of 93.8% after 350 cycles. The overall production cost is reduced by 16% compared to traditional open-cell formation.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cylindrical battery formation apparatus, characterized in that, Includes a formation-specific tray (3) for supporting the battery cell (1), a rubber nail (2) for sealing the liquid injection port of the battery cell (1), a pressure plate (4) for fixing the rubber nail (2), and a formation probe assembly for electrical connection with the terminal of the battery cell (1): The end face of the glue nail (2) is designed to mimic the outline of the liquid injection port of the battery cell (1) to form a glue nail mimic end face (22). The glue nail (2) is provided with a closed glue nail gas chamber (21) for buffering the formation of gas. The pressure plate (4) is provided with limiting holes (41) corresponding to the glue nails (2). The upper part of the glue nails (2) is embedded in the corresponding limiting holes (41). The pressure plate (4) can apply a uniform pressure of 0.2–0.3 MPa to the glue nails (2). The formation probe assembly is all located on the same side of the cell (1), including a negative electrode probe (5) located in the middle and a positive electrode probe (6) surrounding the edge.

2. A formation method for a cylindrical battery formation apparatus according to claim 1, characterized in that, Includes the following steps: S1: After the battery cell (1) is filled with electrolyte, a rubber nail (2) is inserted. After the battery cell (1) has completed one filling, in a dry environment with a room temperature of 20–25℃ and a dew point value of ≤-40℃, the rubber nail (2) with its own air chamber is slowly inserted into the filling port of the battery cell (1) so that the conformal end face (22) of the rubber nail fits tightly with the filling port without gaps or deviations; the amount of electrolyte added in one filling is 80%–85% of the electrolyte volume corresponding to the rated capacity of the battery cell (1); S2: Battery cell (1) assembly tray: neatly place the battery cells (1) with the glue nails (2) inserted into the special forming tray (3), and control the spacing between the battery cells (1) to be 5–8 mm; S3: Apply pressure, align the pressure plate (4) with the limiting holes (41) corresponding to the glue nails (2) with the forming special tray (3) with the glue nails (2) of the battery cell (1), so that the upper part of each glue nail (2) is embedded in the corresponding limiting hole (41), apply a uniform pressure of 0.2-0.3MPa to the pressure plate (4) and fix the relative position of the pressure plate (4) and the forming special tray (3); S4: Formation, send the special formation tray (3) containing the battery cell (1) and the pressure plate (4) into the formation equipment, adjust the position of the formation probe so that the middle negative electrode probe (5) contacts the negative electrode post of the battery cell (1) and the edge positive electrode probe (6) contacts the positive electrode post of the battery cell (1). The contact pressure between the probe and the post is controlled at 0.1–0.2MPa. Start the formation equipment and charge it at a constant current of 0.05–0.5C in 3–4 stages for 7 hours at an ambient temperature of 35–45℃, gradually increasing the voltage of the battery cell (1) to 4.2V. S5: Remove the pressure plate (4). After the formation is completed, transfer the formation special tray (3) together with the pressure plate (4) to the replenishment room. Remove the fastening structure of the pressure plate (4) in a dry environment and remove the pressure plate (4). S6: Disassembling the tray and removing the glue nail (2), remove the battery cell (1) from the special tray (3) to complete the disassembly, and slowly remove the glue nail (2) using special equipment and tooling. Keep the battery cell (1) vertical during the process of removing the glue nail (2). Immediately after removing the glue nail (2), transfer the battery cell (1) to the liquid replenishment station. S7: Replenishing and sealing: Replenish the electrolyte with the same type as the first electrolyte in the electrolyte injection port of the cell (1) after removing the glue pin (2). The replenishment amount is 15%–20% of the electrolyte amount corresponding to the rated capacity of the cell (1). After replenishment, immediately seal the cell (1).

3. The cylindrical battery formation apparatus according to claim 1, characterized in that, The material of the rubber nail (2) is a polymer material that is resistant to electrolyte corrosion and has excellent elasticity, preferably fluororubber. The fluororubber can adapt to temperature changes of 25–60℃ and pressure fluctuations of 0–1.5MPa, and does not react with the electrolyte.

4. The cylindrical battery formation apparatus according to claim 1, characterized in that, The gap between the inner diameter of the limiting hole (41) of the pressure plate (4) and the upper outer diameter of the rubber nail (2) is 0.2–0.6 mm; the pressure plate (4) is fixedly connected to the chemical forming special tray (3) by fastening bolts to ensure that the pressure applied to all rubber nails (2) is uniform and consistent, and does not hinder the elastic deformation and pressure relief function of the rubber nail air chamber (21).

5. The cylindrical battery formation apparatus according to claim 1, characterized in that, The formation tray (3) is made of aluminum alloy or engineering plastic. The formation tray (3) is provided with a positioning groove that is compatible with the bottom of the cell (1). The bottom of the positioning groove of a single cell (1) can withstand a pressure of not less than 0.5MPa, and the formation tray (3) can withstand a long-term formation working temperature of 35–45℃.

6. The method for forming a cylindrical battery according to claim 2, characterized in that, In step S4, when the formation process is carried out in three stages, the first stage is charged with a constant current of 0.05–0.1C to the cell (1) voltage of 3.0V, the second stage is charged with a constant current of 0.1–0.3C to the cell (1) voltage of 3.8V, and the third stage is charged with a constant current of 0.3–0.5C to the cell (1) voltage of 4.2V. The total charging time for the three stages is 7 hours.

7. The method for forming a cylindrical battery according to claim 2, characterized in that, In step S4, after each charging stage is completed, the elastic deformation of the glue nail gas chamber (21) is used to achieve a step-by-step depressurization, and the formation gas buffered in the glue nail gas chamber (21) is discharged in an orderly manner. During the depressurization process, the pressure of the pressure plate (4) on the glue nail (2) remains unchanged until all formation stages are completed.

8. A method for producing a cylindrical battery according to claim 2, characterized in that, In step S6, the removal speed of the adhesive pin (2) of the special equipment tool is controlled at 0.5–1 mm / s, and the removal direction coincides with the axis of the liquid injection port of the battery cell (1). After the adhesive pin (2) is removed, the battery cell (1) stays at the liquid replenishment station for no more than 5 minutes.

9. A method for forming a cylindrical battery according to claim 2, characterized in that, The steps S6 and S7, including removing the glue pins (2), replenishing the liquid, and sealing the opening, are all carried out in a dry environment with a dew point value of ≤-40℃. During the replenishment process, the battery cell (1) is kept vertical, and the sealing operation is completed within 1 minute after the replenishment is completed.

10. A method for forming a cylindrical battery according to claim 2, characterized in that, The method is compatible with 26, 32, 46, and 60 series cylindrical batteries, and is especially suitable for high-energy-density cylindrical batteries with a high-nickel cathode-silicon-carbon anode system. The high-nickel cathode includes NCM811 and NCM911, and the compatible cylindrical batteries have a rated capacity of ≥6Ah.

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