A manufacturing process for an energy storage device

Abstract

This invention discloses a manufacturing process for energy storage devices, including cell preparation, electrolyte injection, cell formation, and cell packaging. Cells, produced by slicing and stacking through rolling, are encapsulated in an aluminum-plastic film and fixed in a fixture. They then enter a packaging equipment, sequentially passing through an inlet transition chamber, a packaging chamber, and an outlet transition chamber. The packaging chamber includes an electrolyte injection area, a formation area, and a packaging area. Cleaned bipolar battery pouch semi-finished products exit the inlet transition chamber and sequentially pass through the electrolyte injection area, formation area, and packaging area of ​​the packaging chamber. The packaged bipolar batteries leave the packaging area and enter the outlet transition chamber, where a capacity testing device is installed to test the bipolar batteries. This invention provides a rapid bipolar battery manufacturing process. Based on current electrolyte injection machines, low dew point environment equipment, formation equipment and fixtures, thermoplastic packaging machines, and electrical systems, the process flow has been redesigned and integrated, improving manufacturing efficiency and yield.

Description

Technical Field

[0001] This invention belongs to the field of energy storage device technology, and specifically relates to a manufacturing process for an energy storage device. Background Technology

[0002] Lithium-ion batteries have the advantage of high energy density, which is why they are widely used in modern life. However, lithium-ion batteries still cannot meet users' demand for longer standby time. Therefore, developing energy storage devices with higher energy density has become an urgent need for the industry.

[0003] Currently, battery packs are mostly assembled from individual cells to modules to battery packs. This multi-level assembly method ensures battery safety, but it sacrifices the battery pack's space utilization rate and energy density. Existing batteries use current collectors to connect multiple energy storage units in series to form a battery energy storage system, namely ETP (Electrode to Pack) batteries. This can reduce the battery's packaging weight and volume, thereby improving its specific energy and specific power, and providing more stable battery performance and lower internal resistance, which also greatly improves battery safety.

[0004] Current unipolar battery pouch packaging technology is relatively complex, has a long turnaround time, and poses significant process control risks, making it difficult to meet the application requirements of ETP battery pouch systems. In particular, the traditional unipolar battery pouch production process cannot meet the formation, venting, and packaging requirements of bipolar battery systems. Furthermore, if a secondary sealing process is adopted, it will pose risks to the highly integrated ETP system. Summary of the Invention

[0005] To address the above problems, this invention proposes a manufacturing process for energy storage devices used in ETP batteries.

[0006] The technical solutions to achieve the above objectives are as follows:

[0007] A manufacturing process for an energy storage device: the energy storage device includes at least one battery cell, the at least one battery cell includes a bipolar electrode sheet, a separator, and an electrolyte. The bipolar electrode sheet includes a current collector, and positive and negative active materials are coated on both sides of the current collector, respectively. The active materials coated on the opposite sides of two adjacent bipolar electrode sheets have opposite polarities. A separator is disposed between two adjacent bipolar electrode sheets. After the current collector is metallized, it is connected to an external power management system and a formation system. The manufacturing process of the energy storage device includes the following steps.

[0008] S1: The positive / negative electrode active materials are formed with the current collector, the prepared electrodes are rolled and cut, and then the bipolar electrodes and the two outermost end electrodes are connected in series to obtain the battery cell. The current collector is metallized to leave the tabs. An aluminum-plastic film is wrapped around the outside of the battery cell to obtain a bipolar battery soft pack semi-finished product.

[0009] S2: The bipolar battery soft pack semi-finished product enters the import transition chamber from the first inlet of the import transition chamber. The import transition chamber is filled with protective gas, and the protective gas cleans the bipolar battery soft pack semi-finished product.

[0010] S3: The cleaned bipolar battery soft pack semi-finished product leaves the inlet transition chamber from the first outlet of the inlet transition chamber and enters the packaging chamber. The packaging chamber includes an injection area, a formation area and a packaging area. The bipolar battery soft pack semi-finished product passes through the injection area, the formation area and the packaging area in sequence in the packaging chamber, and completes the injection, formation and packaging steps respectively.

[0011] S4: The encapsulated bipolar battery leaves the encapsulation area and enters the outlet transition chamber. The outlet transition chamber includes a second inlet and a second outlet. The encapsulated bipolar battery leaves the encapsulation area and enters the outlet transition chamber through the second inlet. A capacity detection device is installed in the outlet transition chamber to detect the bipolar battery. The bipolar battery that has completed the detection leaves the outlet transition chamber through the second outlet, thus completing the manufacturing process.

[0012] In a further improvement, the protective gas in the inlet transition chamber in step S2 is preferably argon, and the argon gas cleans the bipolar battery soft-pack semi-finished product three times.

[0013] In a further improvement, the liquid injection machine is preferably integrated into the liquid injection area in step S3 or connected to an independent liquid injection machine. The liquid injection machine is equipped with a liquid injection needle, which is combined with the liquid injection port of the bipolar battery soft pack semi-finished product to perform quantitative liquid injection.

[0014] In a further improvement, the encapsulation chamber in step S3 is preferably sealed and connected to a dehumidifier, which continuously dehumidifies the encapsulation chamber to ensure that the encapsulation chamber is in a low water-to-oxygen ratio state, wherein the water-to-oxygen ratio is ≤ 1 ppm.

[0015] In a further improvement, the formation zone in step S3 is preferably provided with an electrical interface, through which the bipolar battery pouch semi-finished product is connected to an external formation system, and the formation system activates the positive and negative electrode active materials of the bipolar battery pouch semi-finished product.

[0016] Further improvements include fixing the outer side of the bipolar battery soft pack semi-finished product with clamps before it enters the imported transition chamber, and thermoplastic sealing the sides and bottom of the bipolar battery soft pack semi-finished product, with the upper end in an open state.

[0017] In a further improvement, the preferred bipolar battery pouch semi-finished product has metal lead-out tabs, which are electrically connected to the external formation system through the electrical interface.

[0018] In a further improvement, the preferred formation zone is also equipped with an exhaust device. In step S3, after the bipolar battery soft pack semi-finished product enters the formation zone, the exhaust device is turned on to discharge the gas generated during the formation of the bipolar battery soft pack semi-finished product.

[0019] Further improvements include the preferred installation of a vacuum pump and a clamp pressurizing device within the encapsulation area. In step S4, after the bipolar battery pouch semi-finished product has been formed, it enters the encapsulation area, and the vacuum pump is activated to evacuate the encapsulation area, while the clamp pressurizing device applies pressure to the clamp.

[0020] In a further improvement, after applying pressure to the clamp in step S3, a thermoforming machine is used to thermoform the upper end of the bipolar battery soft pack semi-finished product. The two sides of the bipolar battery soft pack semi-finished product are aluminum films, the clamp is clamped on the aluminum films on both sides, and the clamp pressurizing device pressurizes the clamp to thermoform the upper end of the bipolar battery soft pack semi-finished product.

[0021] This invention addresses the liquid injection, formation, and encapsulation challenges of ETP (Electro-Polymerized Tolerancing) structures. Compared to traditional unipolar batteries, bipolar batteries consist of two positive and negative unipolar electrodes connected in series with several bipolar electrodes, enabling high-voltage electrochemical systems. The ETP structure, based on bipolar batteries, directly encapsulates the electrode sheets into a module system, reducing the need for traditional single-cell casings and eliminating the module assembly process. This significantly improves energy density, reduces system cost, and offers advantages such as lower internal resistance and system simplification.

[0022] This invention addresses the ETP bipolar battery pouch structure by designing a highly integrated device that meets the requirements of liquid injection, formation, and packaging, and by designing an automated manufacturing process to ensure high-quality and high-efficiency output.

[0023] This invention designs a manufacturing process for energy storage devices. It redesigns and combines currently mainstream liquid injection machines, low dew point environment equipment, formation equipment and fixtures, thermoplastic packaging machines, and electrical systems, and develops process procedures for integrated production of ETP bipolar battery pouch structures. First, based on the special structure of the ETP bipolar battery pouch, each independent positive and negative electrode unit is led out and connected to the formation fixture. That is, the ETP bipolar battery pouch is first fixed in the formation fixture, ensuring the connection of the independent positive and negative electrode units. Then, it enters the inlet transition chamber for 3-4 protective gas purgings. During this process, the ETP bipolar battery pouch structure remains open. Next, quantitative liquid injection is performed, with appropriate injection rates and immersion times selected. After complete immersion, the formation process begins. Significant gas generation occurs during the formation process; a low dew point environment is provided, and positive pressure gas is promptly discharged. After formation and venting, the pouch enters the packaging process, where it is thermoplastically packaged with an aluminum-plastic film. The entire process is carried out in a low dew point environment. After packaging, the battery enters the outlet transition chamber for 3-4 protective gas cleaning cycles, finally producing a complete ETP bipolar battery pouch product.

[0024] This invention addresses the problems of liquid injection-formation-packaging in the actual production process of ETP bipolar battery pouches by designing a highly integrated device to ensure high-efficiency and high-quality output. It effectively solves the following problems: (1) the difficulty in forming each independent positive and negative electrode unit in the ETP bipolar battery pouch, including the need for timely venting after formation; (2) the traditional process requires secondary sealing, while this invention only requires one packaging. The ETP bipolar battery pouch semi-finished product is in an open state in the early stage, which greatly improves the convenience in the actual process; (3) the entire process is carried out in a low dew point environment and controlled by an electrical system, ensuring product consistency and achieving high-quality and high-efficiency production. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an existing single-cell battery structure.

[0026] Figure 2 This is a schematic diagram of the bipolar battery structure of the present invention.

[0027] Figure 3 This is a schematic diagram of a battery in which a conductive polymer is used as a bipolar electrode.

[0028] Figure 4 This is a schematic diagram of a bipolar electrode metal cap structure.

[0029] Figure 5 This is a schematic diagram of a traditional battery soft-pack liquid injection equipment.

[0030] Figure 6 This is a schematic diagram of the structure of a semi-finished ETP bipolar battery pouch.

[0031] Figure 7 This is an integrated ETP bipolar battery manufacturing equipment.

[0032] Figure 8 The fabrication process flow diagram of the energy storage device of this invention is shown below. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] Combination Figure 1 The existing single-cell battery 10 includes a positive current collector 11, a negative current collector 13, and a separator 12. The positive current collector 11 is mostly aluminum foil coated with a positive active material 15, and the negative current collector 13 is mostly copper foil coated with a negative active material 14. The current mainstream single-cell battery structure is as follows. Figure 1 As shown, lithium-ion batteries possess advantages such as high specific energy, high voltage, low self-discharge, good cycle performance, and long lifespan, leading to their widespread use in power batteries and energy storage systems. Currently, most individual cells in power and energy storage systems adopt cylindrical, square aluminum shells, or pouch designs, with each cell having its own independent casing. Based on this characteristic, battery cells are assembled into battery modules and then integrated to form battery packs. This process involves connecting cells and modules in series and parallel to meet the requirements of power or energy storage systems. However, this connection method increases the weight and connection impedance of the battery due to the tabs, connectors, and battery casing, reducing the battery's power density and energy density, and also increasing potential safety hazards.

[0035] like Figure 2 As shown, the bipolar battery structure includes multiple electrode sheets, which are assembled into a cell 20 by alternating stacking of electrode sheets, separators, and electrolytes. The cell is covered by a shell. The two outermost electrode sheets are coated with positive electrode active material 22 and negative electrode active material 23 on one side, respectively. There is an outer negative electrode 26, an outer positive electrode 21, and a cell series assembly 150. The two ends of the cell series assembly 150 are respectively positive and negative terminals. The outer negative electrode 26 is connected to the negative terminal, and the outer positive electrode 21 is connected to the positive terminal. The cell series assembly includes multiple overlapping bipolar electrode sheets. A separator 25 is provided between each two adjacent bipolar electrode sheets to block the passage of electrons. Each two adjacent inner bipolar electrode sheets 24 form a power supply unit, and multiple power supply units are connected in series.

[0036] The bipolar electrode sheets are tightly bonded to the separator, thereby reducing the space occupied by multiple bipolar electrode sheets 24 and thus reducing the overall size of the battery. Each bipolar electrode sheet includes an internal current collector, a positive active material layer, and a negative active material layer. The positive and negative active material layers are coated on both sides of the internal current collector. A separator 25 is disposed between each positive active material layer and the adjacent negative active material layer, and the positive and negative active material layers are bonded to their respective internal separators 25, further reducing the overall volume of the cell. A bipolar battery is a battery module formed by stacking and connecting several battery cells in series using bipolar electrodes inside the battery. This reduces the battery's packaging weight and volume, thereby improving its specific energy and specific power, and providing more stable battery performance and lower internal resistance.

[0037] In contrast, bipolar batteries have the following characteristics: (1) They do not have the tabs, connectors, structural components, and battery casings found in current battery packs, which increases the proportion of active materials in the battery system and improves the specific power and specific energy of the battery system; (2) The current direction is perpendicular to the electrode, and the current passes through a very thin bipolar electrode, which reduces the current transmission path and increases the current cross-sectional area, making the current distribution in the battery more uniform, shortening the electron migration channel, and reducing the internal resistance of the battery; (3) If a battery cell inside a bipolar battery is short-circuited, it will not cause an instantaneous large current discharge of all battery cells inside the battery. Only a small amount of heat is generated inside the single battery, and the battery can still be used, but the output voltage of the battery will be reduced; (4) Bipolar power batteries can be connected in parallel to form a group, which can simplify the design of the battery pack management system and reduce the cost of the power battery integration system. In addition, parallel battery packs can achieve fast charging / discharging without requiring special requirements for electrode materials or electrode coating thickness.

[0038] like Figure 3 As shown, in this embodiment, a conductive polymer is used as the bipolar electrode, which has good flexibility and high conductivity. Simultaneously, using the polymer as the current collector 24 further reduces the system mass and increases the energy density. Furthermore, as... Figure 4As shown, the polymer-based bipolar current collector is metallized using a vapor deposition process. The metallized polymer current collector can be welded with wires to connect to the battery management system, enabling electrochemical monitoring at the electrode level within the battery system. To facilitate the connection of each electrode to the power management system lead wires, each polymer current collector has a portion exposed at one end after encapsulation, where it is metallized. Specifically, the metallized portion is the external end of the bipolar current collector, forming a cap-like structure that encloses the end of the current collector. The metallization structure can include single-sided metallization of the current collector. To avoid welding errors during engineering, this invention chooses double-sided metallization and provides an end to form a cap-like structure, ensuring effective welding while increasing the bonding stability of the metallization. Vapor deposition is used to prepare the current collector metallization layer, which forms a dense and stable metallization layer, ensuring the cycle stability of the battery system while exhibiting excellent thermal and electrical conductivity, meeting various operating environments and ensuring timely and effective battery management.

[0039] like Figure 5 As shown, the current mainstream soft-pack electrolyte injection process uses multiple soft-pack clamps grouped together to enter the electrolyte injection environment tank, and electrolyte is introduced through external tubing for syringe injection. This injection technology is not suitable for ETP bipolar battery soft packs, and suffers from problems such as technical complexity, long turnaround time, and difficulty in water and oxygen control. Figure 6 As shown, Figure 4 An aluminum-plastic film 30 is placed on both sides and the bottom surface of the prepared ETP bipolar cell 20, and the aluminum-plastic film 30 on both sides and the bottom surface of the ETP bipolar cell 20 is thermoplastically encapsulated, with the top end in an open state. Figure 7As shown, after the ETP bipolar battery pouch semi-finished product with both sides and bottom surface thermoplastic sealing is clamped by the fixture, it enters the inlet transition chamber 41 of the integrated ETP bipolar battery manufacturing equipment through the first inlet. The inlet transition chamber 41 is filled with protective gas, which cleans the ETP bipolar battery pouch semi-finished product three times. In this embodiment, argon gas is used. After cleaning, the ETP bipolar battery pouch semi-finished product leaves the inlet transition chamber 41 through the first outlet and enters the liquid injection area 42. The liquid injection area 42 has a built-in liquid injection machine or is connected to an external liquid injection machine. The liquid injection needle of the liquid injection machine is connected to the ETP bipolar battery pouch semi-finished product. The electrolyte injection ports of the TP bipolar battery pouch semi-finished product are aligned and quantitatively injected to ensure that the electrolyte is wetted before entering the formation zone 43. The formation zone 43 provides a constant temperature environment and is equipped with an electrical interface to allow the injected ETP bipolar battery pouch semi-finished product in the formation zone 43 to be electrically connected to the external formation system. The formation system activates the positive and negative electrode active materials 15 and 14 of the bipolar battery. The ETP bipolar battery pouch semi-finished product is electrically connected to the external formation system through the electrical interface via metal lead-out tabs. Because gas generation occurs during the formation process, it is necessary to vent the gas in a timely manner and ensure a low water-to-oxygen ratio in a low dew point environment. The optimal water-to-oxygen ratio is ≤ 1 ppm, so an venting device needs to be installed in the formation zone.

[0040] After the ETP bipolar battery pouch semi-finished product undergoes formation and degassing, it enters the packaging area 44. The packaging area 44 is connected to a vacuum device, which evacuates the packaging area 44. Simultaneously, a clamp pressurizes the ETP bipolar battery pouch semi-finished product, thermoforming and sealing the upper end of the semi-finished product. The sealed ETP bipolar battery pouch enters the outlet transition chamber 45 through the second inlet. The outlet transition chamber 45 is equipped with a capacity testing device that tests the ETP bipolar battery pouch to determine if its capacity meets the standard. Qualified ETP bipolar battery pouches are produced from the second outlet of the outlet transition chamber 45. The complete process can be found in [link to process details]. Figure 8 As shown, this manufacturing process meets the requirements for electrolyte injection, formation, and sealing of ETP bipolar battery pouch cells, achieving a highly integrated design, enabling continuous production, and ensuring a low dew point environment. The pouch sealing process is a single step, reducing process risks and improving yield and consistency. As shown in Table 1, from a process engineering perspective, traditional segmented electrolyte injection, formation, and sealing processes are numerous and difficult to manage risks. This invention highly integrates different processes and maintains a low dew point environment throughout, effectively controlling failures and improving the actual yield by approximately 10%.

[0041] Table 1 Comparison of yield rates between existing processes and ETP integrated processes

[0042]

[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for fabricating an energy storage device, characterized by: The energy storage device includes at least one electric core, the at least one electric core includes bipolar electrode sheet, diaphragm and electrolyte, the bipolar electrode sheet includes current collector, the two sides of the current collector are coated with positive active material and negative active material respectively, the opposite surfaces of the adjacent two bipolar electrode sheets are coated with active materials with opposite polarities, the diaphragm is arranged between the adjacent two bipolar electrode sheets, the current collector is metalized to connect the external power management system and the formation system, the current collector is metalized to at least one end of the device after the device is packaged, and the leaking end of the current collector is double-sided metalized, the current collector is metalized by means of gas deposition, the external end of the current collector is metalized to form a cap-shaped structure covering the end of the current collector, and the manufacturing process of the energy storage device includes the following steps. S1: the positive / negative active material is formed with the current collector, the prepared electrode is rolled and cut, then the bipolar electrode and the two outermost end electrodes are connected in series to obtain the electric core, the current collector is metalized to leave the tab, the electric core is sleeved with the aluminum plastic film to obtain the bipolar battery soft package semi-finished product; S2: the bipolar battery soft package semi-finished product is transferred from the first inlet of the inlet transition chamber to the inlet transition chamber, the inlet transition chamber is filled with protective gas, and the protective gas cleans the bipolar battery soft package semi-finished product; S3: the cleaned bipolar battery soft package semi-finished product leaves the inlet transition chamber from the first outlet of the inlet transition chamber and enters the packaging chamber, the packaging chamber includes a liquid injection area, a formation area and a packaging area, and the bipolar battery soft package semi-finished product sequentially passes through the liquid injection area, the formation area and the packaging area in the packaging chamber to complete the steps of liquid injection, formation and packaging respectively; S4: the bipolar battery after completing the packaging leaves the packaging area and enters the outlet transition chamber, the outlet transition chamber includes a second inlet and a second outlet, the bipolar battery after completing the packaging in the packaging area leaves the packaging area, enters the outlet transition chamber from the second inlet, the outlet transition chamber is provided with a capacity detection device, the capacity detection device detects the bipolar battery, and the bipolar battery after completing the detection leaves the outlet transition chamber through the second outlet to complete the preparation.

2. The energy storage device manufacturing process of claim 1, wherein, The protective gas in the inlet transition chamber in the step S2 is argon, and the argon cleans the bipolar battery soft package semi-finished product three times.

3. The energy storage device manufacturing process of claim 1, wherein, The liquid injection area in the step S3 is integrated with a liquid injection machine or connected with an independent liquid injection machine, the liquid injection machine is provided with a liquid injection needle, and the liquid injection needle is combined with the liquid injection port of the bipolar battery soft package semi-finished product to perform quantitative liquid injection.

4. The energy storage device manufacturing process of claim 3, wherein, The packaging chamber in the step S3 is sealed and connected with a dehumidifier, the dehumidifier continuously dehumidifies the packaging chamber to ensure that the packaging chamber is in a low water-oxygen ratio state, and the water-oxygen ratio is less than or equal to 1 ppm.

5. The energy storage device manufacturing process of claim 4, wherein, The formation area in the step S3 is provided with an electrical interface, the bipolar battery soft package semi-finished product is connected with an external formation system through the electrical interface, and the formation system activates the positive and negative active materials of the bipolar battery soft package semi-finished product.

6. The energy storage device manufacturing process of claim 5, wherein, The bipolar battery soft package semi-product is fixed by a clamp outside before entering the import transition bin, and the two sides and the bottom of the bipolar battery soft package semi-product are thermoplastically packaged, and the upper end is in an open state.

7. The energy storage device manufacturing process of claim 6, wherein, The bipolar battery soft package semi-product is connected to the outside formation system through the metal lead-out tab and the electrical interface.

8. The energy storage device manufacturing process of claim 5, wherein, The formation area is also provided with an exhaust device, and in step S3, after the bipolar battery soft package semi-product enters the formation area, the exhaust device is opened to exhaust the gas generated during the formation of the bipolar battery soft package semi-product.

9. The energy storage device manufacturing process of claim 5, wherein, The packaging area is provided with a vacuum pumping device and a clamp pressing device, and in step S4, after the bipolar battery soft package semi-product is formed, the bipolar battery soft package semi-product enters the packaging area, the vacuum pumping device is opened to pump the packaging area, and the clamp pressing device is used to press the clamp.

10. The energy storage device manufacturing process of claim 9, wherein, After the clamp is pressed in step S3, a thermoplastic machine is used to thermoplastically seal the upper end of the bipolar battery soft package semi-product, the two sides of the bipolar battery soft package semi-product are aluminum films, the clamp is clamped on the two sides of the aluminum film, and the clamp pressing device is used to press the clamp to thermoplastically seal the upper end of the bipolar battery soft package semi-product.

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