Manufacturing method for high-capacity battery, semi-finished single battery, battery cell, and high-capacity battery

Abstract

The present invention discloses a manufacturing method for a high-capacity battery, a semi-finished single battery, a battery cell, and a high-capacity battery. The method comprises: manufacturing multiple semi-finished single batteries or battery cells that are not injected with an electrolyte, connecting the semi-finished single batteries or the battery cells in parallel and then placing same in a box body, sealing the box body, and injecting electrolyte into the box body, such that the electrolyte of an inner cavity of each semi-finished single battery or the electrolyte of an inner cavity of each battery cell and the electrolyte in the box body are in one electrolyte system, and then performing a formation operation to complete the manufacturing of the high-capacity battery. Compared with existing high-capacity battery manufacturing methods, processes of liquid injection, sealing, and formation of each single battery are removed, a process of secondary unpacking of each single battery is removed, and high-capacity battery manufacturing efficiency is greatly improved.

Description

Method for manufacturing large-capacity battery, semi-finished single cell battery, battery cell and large-capacity battery Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a method for manufacturing a large-capacity battery, a semi-finished single cell battery, a battery single cell, and a large-capacity battery. Background Art

[0002] Currently, many batteries on the market are connected in parallel or in series to form large-capacity batteries (also known as battery modules or battery packs).

[0003] There is a large-capacity battery that is composed of multiple single cells and a box. Since each single cell is in a shared electrolyte system, the consistency of each single cell is ensured, and the cycle life of the large-capacity battery is improved. The production process of this large-capacity battery is roughly as follows:

[0004] Production of finished single battery cells

[0005] The electrode assembly is assembled in the form of winding or stacking, and then the electrode assembly is placed in the shell. The electrolyte is then injected into the shell for the first time, and the single cell is sealed and subjected to formation and other operations. The finished single cell is completed.

[0006] Making large-capacity batteries

[0007] The single cells in the same group are connected in parallel, placed in a box, and then subjected to secondary liquid filling and formation to complete the production of large-capacity batteries.

[0008] According to the above method, the production of existing large-capacity batteries first involves the step of filling the single cells with liquid, then sealing and forming the single cells; in addition, the production of large-capacity batteries also involves the steps of secondary opening and secondary filling of each single cell.

[0009] Therefore, in the actual production process, it is found that the process of manufacturing large-capacity batteries using the above method is complicated and the cost is high.

[0010] Summary of the Invention

[0011] In order to solve the problems of complicated and high cost in the existing large-capacity battery manufacturing process, the present invention provides the following three large-capacity battery manufacturing methods.

[0012] The first production method comprises the following steps:

[0013] Assembling a semi-finished single battery that has not been injected with electrolyte; the shell of the semi-finished single battery is provided with at least one first through hole;

[0014] Assembling semi-finished high-capacity batteries;

[0015] Place a plurality of semi-finished single cells in a box, connect the inner cavity of each semi-finished single cell to the inner cavity of the box through the first through-hole, seal the box, and connect the poles of each semi-finished single cell extending out of the box in parallel to form a semi-finished high-capacity battery;

[0016] Infusion and formation;

[0017] Electrolyte is injected into the semi-finished large-capacity battery so that each single cell is in a unified electrolyte system, and then the formation operation is performed to complete the production of the large-capacity battery.

[0018] The second production method comprises the following steps:

[0019] Assembling semi-finished single cells that have not been injected with electrolyte;

[0020] Assembling semi-finished high-capacity batteries;

[0021] Before placing a plurality of semi-finished single cells into a box, or after placing a plurality of semi-finished single cells into the box, a first through hole is formed on the outer shell of each semi-finished single cell, so that the inner cavity of each semi-finished single cell is connected to the inner cavity of the box, and then the poles of each semi-finished single cell extending out of the box are connected in parallel, and then the box is sealed to form a semi-finished high-capacity battery;

[0022] Infusion and formation;

[0023] Electrolyte is injected into the semi-finished large-capacity battery so that each single cell is in a unified electrolyte system, and then the formation operation is performed to complete the production of the large-capacity battery.

[0024] Furthermore, the first and second methods further include performing a vacuuming step on the semi-finished large-capacity battery; the purpose of this step is to remove impurities from the inner cavity of the box and the inner cavity of each semi-finished single battery, and further to generate a negative pressure in the inner cavity of the box and the inner cavity of each semi-finished single battery;

[0025] Furthermore, the first and second methods mentioned above also include a step of aging the large-capacity batteries after formation.

[0026] The semi-finished single battery used in the first manufacturing method includes a shell, a positive electrode column, a negative electrode column and an electrode assembly; the positive electrode column and the negative electrode column are insulated and fixed to the top plate of the shell; a portion of the positive electrode column and the negative electrode column extends out of the top of the shell; the other portion of the positive electrode column and the negative electrode column extends into the shell and is connected to the electrode assembly arranged in the shell; no electrolyte is injected into the shell; and a first through hole is provided on the shell.

[0027] Furthermore, at least one first through hole is provided on the top of the housing.

[0028] Furthermore, at least one first through hole is provided on the bottom or side wall of the shell, and a third through hole is provided on the top of the shell.

[0029] The semi-finished single battery used in the second manufacturing method includes a shell, a positive electrode column, a negative electrode column and an electrode assembly;

[0030] The positive electrode column and the negative electrode column are insulated and fixed to the top plate of the shell; a portion of the positive electrode column and the negative electrode column extends out of the top of the shell; the other portion of the positive electrode column and the negative electrode column extends into the shell and is connected to the electrode assembly arranged in the shell; no electrolyte is injected into the shell.

[0031] Furthermore, the shell is provided with at least one sealing and unpacking mechanism.

[0032] Furthermore, there are two sealing and unpacking mechanisms, one of which is arranged on the side wall in the thickness direction of the shell or on the bottom of the shell, and the other is arranged on the top of the shell.

[0033] The third preparation method comprises the following steps:

[0034] Assembling battery cells;

[0035] A first through hole is formed on the first cylindrical body with an open top;

[0036] Connect the upper cover assembly and the bare battery cell by welding to form a battery cell unit;

[0037] Place the bare battery cell of the battery unit in the first cylinder, and fix the periphery of the upper cover assembly to the periphery of the open end of the first cylinder by partial connection, ensuring that there is a gap between the periphery of the upper cover assembly and the periphery of the open end of the first cylinder, thereby completing the production of the battery cell;

[0038] Assembling large-capacity batteries;

[0039] Place multiple battery cells in the box, ensure that the inner cavity of each battery cell is connected to the inner cavity of the box through the first through hole, and ensure that the positive and negative poles of each battery cell extend out of the top of the box, and then seal the box;

[0040] Electrolyte is injected into the box so that each battery cell is in a unified electrolyte system, and then the formation operation is performed to complete the production of large-capacity batteries.

[0041] This method can complete the production of large-capacity batteries composed of battery cells with only one liquid injection. Compared with the existing method, it reduces the steps of liquid injection, sealing, and formation of each single cell, as well as the step of secondary unpacking of the single cell, greatly improving the production efficiency of large-capacity batteries.

[0042] Furthermore, during the assembly of the battery cell of the present invention, the upper cover assembly is fixed to the open end of the first barrel by partial connection. This saves manufacturing time and improves manufacturing efficiency compared to the existing single cell assembly of large-capacity batteries in which the upper cover assembly is fixed to the open end of the first barrel by full welding.

[0043] In addition, since the upper cover assembly and the open end of the first cylinder are connected by a local connection, there is a gap between the open end of the cylinder and the upper cover. The gas in the battery cell can be discharged through the gap during liquid injection. Compared with the existing method of using secondary unpacking to produce large-capacity batteries, there is pressure in the gas area of ​​the single cell, which leads to the problem of poor electrolyte injection.

[0044] Furthermore, the above-mentioned third method also includes electrically connecting the part of the positive electrode column in each battery cell extending out of the top of the box to form the total positive electrode of the large-capacity battery, and electrically connecting the part of the negative electrode column in each battery cell extending out of the top of the box to form the total negative electrode of the large-capacity battery.

[0045] Furthermore, the third method also includes the steps of attaching at least one heat exchange tube to the total positive and negative electrodes of the large-capacity battery before liquid injection, drying and heating each battery cell via the heat exchange tube, and evacuating the housing after drying and heating. The heat exchange tubes can directly heat each battery cell during large-capacity battery production to control the water content within the bare cells. Compared to traditional vacuum baking methods, this eliminates the need for a dedicated vacuum baking oven, reducing the production cost and improving the efficiency of large-capacity battery production. To extract the dried gas from the housing and facilitate liquid injection, the method also includes evacuating the housing during the drying and heating process.

[0046] Furthermore, the third method further includes a step of aging the formed large-capacity battery.

[0047] The battery cell used in the third method includes a battery cell unit and a first cylinder; the battery cell unit includes an upper cover assembly and a bare battery cell; the upper cover assembly includes a cover body, a positive electrode column and a negative electrode column; the positive electrode column and the negative electrode column are insulated and fixed on the cover body; a part of the positive electrode column and the negative electrode column extends out of one side of the cover body, and the other part of the positive electrode column and the negative electrode column extends out of the other side of the cover body and is connected to the bare battery cell; the top of the first cylinder is open, and a first through hole is opened on the side wall or bottom of the first cylinder; the bare battery cell is located in the cylinder, and the edge of the cover body and the periphery of the open end of the first cylinder are fixed by local connection, so that there is a gap between the open end of the first cylinder and the upper cover.

[0048] Compared with the single cells used in existing large-capacity batteries, the battery cells used in the third method do not require a liquid injection part, and do not require operations such as liquid injection and formation. The upper cover assembly and the cylinder only need to be fixed by spot welding, and the operation of airtightness testing of the battery cells can also be saved. Therefore, the structure of the battery cell is simple and the manufacturing process is simple, which reduces the cost of the battery cell and thus reduces the manufacturing cost of large-capacity batteries.

[0049] Furthermore, the positive pole and the negative pole are provided with mounting portions for arranging heat exchange tubes.

[0050] The large-capacity battery manufactured by the third method includes a box body and a plurality of the above-mentioned battery cells; a first interface is provided on the box body; a second through hole is provided on the top of the box body for leading out the positive and negative poles of each battery cell; each battery cell is placed side by side in the box body, and the positive and negative poles of each battery cell are led out through the second through hole, and the second through hole and the corresponding positive or negative pole of the battery cell are kept sealed; the part of the positive pole on each battery cell extending out of the second through hole is electrically connected to form the total positive pole of the large-capacity battery, and the part of the negative pole on each battery cell extending out of the second through hole is electrically connected to form the total negative pole of the large-capacity battery; each battery cell is connected to the box body through the first through hole on the cylinder body, so that each battery cell is in a shared electrolyte system.

[0051] Furthermore, the case of the large-capacity battery comprises a housing and end plates fixedly sealed to both ends of the housing; the first interface is provided on the end plates. This first interface can be connected to a fluid injection / exchange device to inject / exchange the large-capacity battery, or it can be connected to a vacuum extraction device to vacuum the large-capacity battery. An explosion relief valve or a sealing plug can also be provided.

[0052] Furthermore, the box body of the above-mentioned large-capacity battery also includes a second interface, which is arranged at a position near the top of the box body on the end plate of the box body or at the top of the box body. The second interface can be equipped with an exhaust valve, which can regularly discharge the gas generated in the large-capacity battery during the operation of the large-capacity battery, thereby reducing the probability of swelling of each battery cell and further reducing the probability of thermal runaway of the large-capacity battery.

[0053] Furthermore, the total positive electrode and the total negative electrode exchange heat with an external temperature control device through at least one heat transfer tube.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] 1. The first and second large-capacity battery manufacturing methods of the present invention use unfilled semi-finished single cells to form semi-finished large-capacity batteries, and then perform vacuuming, liquid injection, and formation operations on the semi-finished large-capacity batteries to produce large-capacity batteries. Compared with the existing methods, the steps of liquid injection, sealing, and formation of each single cell, as well as the step of secondary unpacking of the single cell are reduced, thereby greatly improving the production efficiency of large-capacity batteries.

[0056] 2. The first and second large-capacity battery manufacturing methods of the present invention perform a vacuuming step on the semi-finished large-capacity batteries before liquid injection, with the aim of removing impurities that may be introduced during the sealing process of the box (generally sealed by welding), and after vacuuming, the box body and the inner cavity of the semi-finished single battery are both in a negative pressure state, which can also ensure that during subsequent liquid injection, the electrolyte can smoothly enter the inner cavity of the box body and the inner cavity of each semi-finished single battery, thereby ensuring the performance of the subsequent large-capacity battery.

[0057] 3. The first through hole is directly preset on the shell of the semi-finished single battery of the first manufacturing method in the present invention, which reduces the sealing and unpacking mechanism for secondary unpacking compared with the existing finished single battery. By directly setting the third through hole on the top of the shell, the use of the explosion-proof membrane is reduced compared with the existing finished single battery. Therefore, the production cost is further reduced.

[0058] 4. The large-capacity batteries manufactured by the first and second manufacturing methods of the present invention can be provided with a second channel on the top of the box body that is connected to the gas area in the inner cavity of each single cell. The second channel can ensure that the air pressure in each single cell is in a balanced system. Each single cell is always under the same air pressure, reducing the differences between the single cells caused by inconsistent air pressure in each single cell. At the same time, an exhaust valve is provided on the second channel to regularly discharge the gas in each single cell, thereby avoiding a series of problems that affect the comprehensive performance of the large-capacity battery, such as swelling of the single cell shell due to the inability to discharge gas.

[0059] 5. The present invention can set a second channel on the top of the box body to cover the explosion venting part on the top of each single battery. When the single battery is in thermal runaway, the explosion venting part is opened, and the thermal runaway flue gas is discharged through the second channel to the external thermal runaway flue gas treatment device for treatment, thereby ensuring the safety of large-capacity batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0061] FIG1 is a flow chart of a method for producing a large-capacity battery in Example 1 and Example 2;

[0062] FIG2 is a schematic structural diagram of a first semi-finished single cell in Example 1;

[0063] FIG3 is a schematic structural diagram of a second semi-finished single cell in Example 1;

[0064] FIG4 is a schematic structural diagram of a large-capacity battery having only a first channel;

[0065] FIG5 is a box structure of the large-capacity battery in FIG4 ;

[0066] FIG6 is a schematic structural diagram of a large-capacity battery having a first channel and a second channel;

[0067] FIG7 is a box structure of the large-capacity battery in FIG6 ;

[0068] FIG8 is a schematic structural diagram of the first semi-finished single cell in Example 2;

[0069] FIG9 is a schematic structural diagram of a second semi-finished single cell in Example 2;

[0070] FIG10 is a schematic structural diagram of a third semi-finished single cell in Example 2;

[0071] FIG11 is a flow chart of a method for producing a large-capacity battery in Example 3;

[0072] FIG12 is a flow chart of assembling a battery cell in step 1 of Example 3;

[0073] FIG13 is a flow chart of step 1 of assembling a large-capacity battery in Example 3

[0074] FIG14 is a structural diagram of a battery cell in Example 3;

[0075] FIG15 is a second structural diagram of a battery cell in Example 3;

[0076] FIG16 is a schematic structural diagram of a battery cell with a groove in Example 3;

[0077] FIG17 is a schematic structural diagram of a battery cell having a through hole in Example 3;

[0078] FIG18 is a schematic structural diagram of a large-capacity battery in Example 3;

[0079] Figure 19 is a schematic structural diagram of the top of the box in Example 3;

[0080] FIG20 is a cross-sectional view of a large-capacity battery in Example 3.

[0081] The reference numerals are as follows:

[0082] 100-semi-finished single battery, 200-large capacity battery, 300-battery single battery;

[0083] 1-shell, 2-positive pole, 3-negative pole, 4-first through hole, 5-first cylinder, 6-upper cover, 7-lower cover, 8-groove, 9-box, 10-single battery, 11-second through hole, 12-pole adapter, 13-hollow component, 14-second cylinder, 15-first cover, 16-second cover, 17-first channel, 18-second channel, 19-third cover, 20-fourth cover, 21-third through hole, 22-sealing and unpacking mechanism, 23-upper cover assembly, 24-bare cell, 25-cell unit, 26-heat exchange tube, 27-cover body, 28-first groove, 29-through hole, 30-first interface, 31-second interface, 32-pad, 33-electrolyte channel, 34-hollow component. DETAILED DESCRIPTION

[0084] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0085] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0086] In the description of the present invention, it should be noted that the terms "top," "bottom," and so on, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," "third," "fourth," and so on, are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0087] The basic design idea of ​​the present invention is:

[0088] By manufacturing multiple semi-finished single cells or battery cells that have not yet been injected with electrolyte, connecting them in parallel and placing them in a box, sealing the box, and then injecting electrolyte into the box, the electrolyte in the inner cavity of each semi-finished single cell or the electrolyte in the inner cavity of each battery cell and the electrolyte in the box are in the same electrolyte system. Then, the formation operation is performed to complete the production of a large-capacity battery. Compared with existing large-capacity battery production methods, this method reduces the steps of injecting, sealing, and forming each single cell, as well as the step of secondary unpacking of the single cells, greatly improving the production efficiency of large-capacity batteries.

[0089] Example 1

[0090] The specific implementation process of the method for manufacturing a large-capacity battery provided in this embodiment is as follows, as shown in FIG1 :

[0091] Step 1: Assembling semi-finished single cells that have not been injected with electrolyte;

[0092] The semi-finished single cell is substantially identical to the commercially available aluminum square lithium-ion battery, except that the semi-finished single cell is not injected with electrolyte and has at least one first through hole.

[0093] Step 2: Assemble semi-finished high-capacity batteries;

[0094] Place a plurality of semi-finished single cells in a box, connect the inner cavity of each semi-finished single cell to the inner cavity of the box through the first through-hole, seal the box, and connect the poles of each semi-finished single cell extending out of the box in parallel to form a semi-finished high-capacity battery;

[0095] In this step, the process of sealing the box is to ensure that the inside of the box is isolated from the external environment. Therefore, the actual sealed areas are at least the following two:

[0096] 1. When placing semi-finished single batteries, the box must have an open end. Therefore, after all semi-finished single batteries are placed in the box, the open end needs to be sealed;

[0097] 2. Since the poles of each semi-finished single cell in the semi-finished large-capacity battery need to extend out of the top of the box, the area on the top of the box for extending the poles needs to be sealed.

[0098] Step 3: injection and formation;

[0099] The electrolyte is injected into the box so that each single cell is in a unified electrolyte system, and then the formation operation is carried out to complete the production of large-capacity batteries.

[0100] In this process, the specific method of formation is:

[0101] After charging to 3.4V at 0.1C constant current, switch to 3.4V constant voltage charging to a cut-off current of 0.01C and let it rest for 30 minutes;

[0102] Then discharge at 0.1C constant current to 2.5V and let it stand for 30 minutes;

[0103] After charging at a constant current of 0.2C to 3.4V, the battery is then switched to a constant voltage charge of 3.4V to a cutoff current of 0.01C and allowed to rest for 30 minutes. This formation process allows each cell in the high-capacity battery to develop a more stable SEI film, giving it more stable cycling performance.

[0104] The above steps 1 to 3 need to be performed in a specific environment, which is preferably an environment with a dew point standard between -25 and 40°C, humidity ≤1%, temperature 23°C±2°C, and cleanliness level 100,000.

[0105] The preferred solution of the above method is that a vacuum step needs to be performed on the semi-finished large-capacity battery before liquid injection and formation;

[0106] Since impurities may be introduced during the sealing process of the box (usually by welding), which may affect the performance of large-capacity batteries, the vacuuming process can remove impurities from the box cavity and the inner cavity of each semi-finished single battery. After vacuuming, the box cavity and the inner cavity of the semi-finished single battery are in a negative pressure state, which can also ensure that the electrolyte can smoothly enter the box cavity and the inner cavity of each semi-finished single battery during subsequent liquid injection;

[0107] It should be noted here that the interface used for vacuuming and liquid injection in step 3 can be one interface on the box body, or it can be two separate interfaces.

[0108] In some embodiments, the large-capacity battery can be aged after formation at an aging temperature of 50° C. and an aging time of 48 hours. After aging, the large-capacity battery can be exhaust-treated to discharge waste gas after formation and reduce the probability of swelling of each single cell of the large-capacity battery.

[0109] Semi-finished single battery

[0110] As shown in Figure 2, the semi-finished single cell 100 includes a shell 1 and an electrode assembly arranged in the inner cavity of the shell; the electrode assembly here is composed of a positive electrode, a separator, and a negative electrode arranged in sequence, and assembled by a lamination or winding process; the positive electrode of the electrode assembly is connected to the positive electrode column 2 on the top of the shell, and the negative electrode of the electrode assembly is connected to the negative electrode column 3 on the top of the shell; no electrolyte is injected into the inner cavity of the shell; at least one first through hole 4 is provided on the shell (the number of first through holes can be more than two, or a first through hole with a larger aperture is provided).

[0111] In some embodiments, the first through hole 4 may be provided on the bottom or side wall of the housing and used for liquid injection and vacuuming when assembling a large-capacity battery.

[0112] In some embodiments, the first through hole 4 may be provided at the top of the housing and used for liquid injection, vacuuming, exhausting and explosion relief when assembling a large-capacity battery.

[0113] As shown in Figure 3, the second semi-finished single cell 100 includes a shell 1 and an electrode assembly arranged in the inner cavity of the shell; the electrode assembly here is composed of a positive electrode, a separator, and a negative electrode arranged in sequence, and assembled by a lamination or winding process; the positive electrode of the electrode assembly is connected to the positive electrode column 2 on the top of the shell, and the negative electrode of the electrode assembly is connected to the negative electrode column 3 on the top of the shell; no electrolyte is injected into the inner cavity of the shell; at least one first through hole is provided on the side or bottom of the shell (the number of the first through holes can be more than two, or a first through hole with a larger aperture is provided), and a third through hole 21 is provided on the top of the shell.

[0114] The first through hole 4 is used for liquid injection and vacuuming when assembling a large-capacity battery; the third through hole 21 is used for exhaust and explosion relief when assembling a large-capacity battery.

[0115] Since both of the above-mentioned semi-finished single cells have at least one first through hole 4, before the semi-finished single cells are assembled into large-capacity batteries, or during storage and transportation, it is necessary to ensure that the electrode assembly of the semi-finished single cells will not be corroded by the external environment. Therefore, the first through hole (and the third through hole) of the semi-finished single cell can be sealed by thin film heat sealing.

[0116] If the film heat sealing method is not adopted, the storage area of ​​the semi-finished single battery cells needs to be set as a specific environment, and the semi-finished single battery cells need to be placed in a transportation warehouse with a specific environment for transportation during transportation.

[0117] In order to further improve the production efficiency of large-capacity batteries, the preferred method is to complete the assembly of semi-finished single cells and semi-finished large-capacity batteries in sequence in a clean workshop (a workshop with the above-mentioned specific environment).

[0118] In addition, the shells of the two semi-finished single-cell batteries mentioned above also have two structural forms, as shown in Figures 2 to 4:

[0119] The first type of housing 1 includes a first barrel 5 and an upper cover 6; the first barrel 5 is open at the top and closed at the bottom. When assembling a semi-finished single cell, the positive and negative poles of the upper cover 6 are first connected to the positive and negative poles of the electrode assembly. The upper cover 6 and the electrode assembly are then placed as a whole into the first barrel from the upper open end. Finally, the upper cover 6 and the open end of the first barrel 5 are welded.

[0120] The second type of shell includes a first barrel 5, an upper cover 6 and a lower cover 7; the first barrel 5 is a structure with open ends at both the upper and lower ends; when assembling a semi-finished single battery, the lower cover 7 is first welded to the lower open end of the first barrel, and then the positive and negative poles of the upper cover 6 are connected to the positive and negative poles of the electrode assembly. Then, the upper cover 6 and the electrode assembly are placed as a whole into the first barrel from the upper open end of the first barrel, and finally, the upper cover 6 and the upper open end of the first barrel 5 are welded.

[0121] It should be emphasized that the outer shell of the semi-finished single battery is made of aluminum material, that is, the first cylinder 5, the upper cover plate 6, and the lower cover plate 7 are all made of aluminum material.

[0122] Moreover, at least one first through hole 4 and one third through hole 21 are both opened in advance on the first barrel 5 , the upper cover 6 and the lower cover 7 before assembling the semi-finished single battery.

[0123] In some other embodiments, the positive and negative electrode posts of the semi-finished single battery cell 100 may be provided with grooves 8 for receiving heat transfer tubes, or electrode adapters may be provided on the positive and negative electrode posts, with the grooves 8 formed on the electrode adapters. The heat transfer tubes may be liquid cooling tubes or heat pipes, and are used to charge the positive and negative electrode posts. Therefore, the heat transfer tubes themselves and the medium inside the heat transfer tubes must be insulated from external devices.

[0124] Large-capacity battery

[0125] Based on the above description of the structure of the semi-finished single cell 100, the structure of the large-capacity battery 200 assembled using the above method and the semi-finished single cell will now be described:

[0126] As shown in Figure 4, the large-capacity battery 200 includes a case 9 and N single cells 10; the N single cells 10 are arranged in parallel in the case 9; a first through hole is provided on the outer shell 1 of each single cell; a liquid filling port (not shown in the figure) is provided on the case 9; a second through hole 11 is provided on the top of the case 9 for leading out the positive and negative poles of each single cell 10, and the top area of ​​the case 9 corresponding to each second through hole 11 is fixedly sealed with the top of the outer shell of the single cell 10 corresponding to the second through hole 11; the electrolyte in each single cell 10 is connected to the electrolyte in the case 9, so that each single cell is in a shared electrolyte system.

[0127] Since the positive and negative electrodes of the single cells 10 in this embodiment are led out of the top of the box, a heat transfer tube can be provided in the groove 8 of the positive electrode of each single cell 10, and a heat transfer tube can be provided in the groove 8 of the negative electrode of each single cell. An external temperature control device is connected to the two heat transfer tubes, thereby achieving temperature control of large-capacity batteries (i.e., heating or cooling large-capacity batteries).

[0128] It should be noted that the positive and negative poles with the grooves 8 may be poles of the semi-finished single battery itself, or may be pole adapters 12 fixedly connected to the poles themselves, with the grooves formed on the pole adapters 12 .

[0129] In this embodiment, the box body 9 is made of aluminum;

[0130] There are two ways to fix and seal the top area of ​​the box body corresponding to each second through hole and the top of the single battery housing corresponding to the second through hole:

[0131] 1. A sealing connector is added between the top area of ​​the case 9 corresponding to the second through hole 11 and the upper cover plate of the single cell 10 corresponding to the second through hole to achieve sealing. Referring to Figures 2 and 4, the sealing connector includes a hollow member 13. The bottom of the hollow member 13 is used to seal with the first area of ​​the single cell 10, and the top of the hollow member 13 is sealed with the second area of ​​the case 9. The first area is the area surrounding any pole on the upper cover plate of any single cell 10; the second area is the area corresponding to any second through hole 11 at the top of the case 9. The area corresponding to the second through hole 11 is the area surrounding any second through hole 11 on the outer surface of the case 9; or the area corresponding to the second through hole 11 is the wall of the through hole. The area surrounding the pole is the area surrounding the insulating gasket on the pole. The insulating gasket is a part on the single cell used to insulate the pole from the upper cover plate of the single cell.

[0132] Second, the area of ​​the box body 9 corresponding to the second through hole 11 and the upper cover plate area around the single cell pole can be directly fixed and sealed by laser welding. This method is generally suitable for cases where the height dimensions of the single cells in the box are relatively consistent.

[0133] Among them, the box structure has the following types:

[0134] 1. Referring to Figures 3 and 4, the box body 9 includes a second cylinder 14 and a second cover plate 16; the top and bottom of the second cylinder 14 are both open, the first cover plate 15 is sealed and fixed (welded) to the top of the second cylinder 14, and the second cover plate 16 is sealed and fixed (welded) to the bottom of the second cylinder 14; 2N second through holes 11 are provided on the first cover plate 15.

[0135] In some embodiments, when only a first through hole is provided on the outer shell of a single cell, in order to allow the electrolyte to smoothly enter the box body 9 and the inner cavity of each semi-finished single cell 100 during the injection process, a first channel 17 extending along the length direction of the single cell arrangement and corresponding to the first through hole on the outer shell of each single cell 10 can be opened on the side wall of the second cylinder 14, or the first cover plate 15, or the second cover plate 16 according to the position of the first through hole on the outer shell of each single cell. When the first channel 17 is provided, the injection port is provided in the area of ​​the box body 9 corresponding to any end of the first channel 17, and the injection port can simultaneously serve as an interface for the vacuum pumping equipment and the injection equipment.

[0136] Specifically,

[0137] When the first through hole 4 is provided on the lower cover plate or the side wall of the single battery, correspondingly, the second cover plate 16 or the side wall of the second cylinder 14 is provided with a first channel 17 for communicating with the first through hole of each single battery. The first channel 17 has the following two functions:

[0138] (1) When vacuuming, impurities can be easily extracted;

[0139] (2) When injecting the electrolyte, the electrolyte can flow more smoothly into the inner cavity of each single cell and the box, so that the electrolyte continuity in the shared electrolyte system is stronger (avoiding the occurrence of liquid interruption).

[0140] When the first through hole 4 is provided on the upper cover of the single battery 10, the first cover 15 is provided with a first channel 17 for communicating with the first through hole 4 of each single battery. The first channel 17 has the following four functions:

[0141] (1) When vacuuming, impurities can be easily extracted;

[0142] (2) When injecting the electrolyte, the electrolyte can flow more smoothly into the inner cavity of each single cell and the box, so that the electrolyte continuity in the shared electrolyte system is stronger (avoiding the occurrence of liquid interruption).

[0143] (3) After the large-capacity battery is assembled, the electrolyte in each single cell and the box body is located at the bottom of the single cell cavity and the bottom of the box body under the action of gravity. Therefore, the first channel can be used as a gas channel during aging or operation. Each single cell is in a gas balance system, which improves the uniformity of each single cell from the perspective of gas pressure, and further improves the cycle performance of the large-capacity battery. Moreover, since the internal pressure of each single cell is basically the same, the risk of thermal runaway of a single cell due to excessive internal pressure is greatly reduced, thereby improving the safety of the large-capacity battery. If an exhaust valve is added to the first channel, the probability of single cell swelling can be further avoided by opening the exhaust valve regularly. Moreover, the exhaust valve can be opened after the large-capacity battery is aged to discharge the gas generated during the aging process. It can also further improve the cycle life of the large-capacity battery.

[0144] (4) An explosion relief valve can be provided on the first channel. In the event of thermal runaway of a single battery, the thermal runaway flue gas is discharged through the first through hole and the first channel to the external thermal runaway flue gas treatment device for timely treatment, thereby reducing the probability of more serious accidents.

[0145] As shown in Figures 5 and 6, in some embodiments, when the first through hole of the single cell is set on the side wall or bottom of the single cell, in order to simultaneously meet the above four functions (1)(2)(3)(4), a third through hole 21 can also be set on the top of the single cell. Then: a second channel 18 can also be set on the first cover plate 15, and 2N second through holes 11 are arranged on both sides of the second channel 18. In this embodiment, the first channel has two functions (1)(2); the second channel has two functions (3)(4).

[0146] 2. As shown in Figures 6 and 7, the box body 9 includes a second cylinder 14, a third cover plate 19, and a fourth cover plate 20; the front and rear portions of the second cylinder 14 are open, the third cover plate 19 is sealed and fixed (welded) to the front portion of the second cylinder 14, and the fourth cover plate 20 is sealed and fixed (welded) to the rear portion of the second cylinder 14; 2N second through holes 11 are opened on the top of the second cylinder 14.

[0147] In some embodiments, when there is only one first through hole on the shell of the single cell, in order to allow the electrolyte to smoothly enter the box body 9 and the inner cavity of each semi-finished single cell 100 during the injection process, a first channel 17 extending along the arrangement direction of the single cells and corresponding to the first through hole on the shell of each single cell 10 can be opened on the top, bottom or side wall of the second cylinder 14 according to the position of the first through hole on the shell of each single cell. When the first channel 17 is provided, the injection port is provided on the end plate corresponding to any end of the first channel 17, and the injection port can simultaneously serve as an interface for the vacuum pumping equipment and the injection equipment.

[0148] Specifically,

[0149] 3 and 4 , when the first through hole 4 is provided on the lower cover plate or side wall of the single battery, the bottom or side wall of the second cylinder 14 is correspondingly provided with a first channel 17 for communicating with the first through hole 4 of each single battery. The first channel has the following two functions:

[0150] (1) When vacuuming, impurities can be easily extracted;

[0151] (2) When injecting the electrolyte, the electrolyte can flow more smoothly into the inner cavity of each single cell and the box, so that the electrolyte continuity in the shared electrolyte system is stronger (avoiding the occurrence of liquid interruption).

[0152] When the first through hole is provided on the upper cover plate of the single battery, correspondingly, a first channel for communicating with the first through hole of each single battery is provided on the top of the second cylinder. The first channel has the following four functions:

[0153] (1) When vacuuming, impurities can be easily extracted;

[0154] (2) When injecting the electrolyte, the electrolyte can flow more smoothly into the inner cavity of each single cell and the box, so that the electrolyte continuity in the shared electrolyte system is stronger (avoiding the occurrence of liquid interruption).

[0155] (3) After the large-capacity battery is assembled, the electrolyte in each single cell and the box body is located at the bottom of the single cell cavity and the bottom of the box body under the action of gravity. Therefore, the first channel can be used as a gas channel during aging or operation. Each single cell is in a gas balance system, which improves the uniformity of each single cell from the perspective of gas pressure, and further improves the cycle performance of the large-capacity battery. Moreover, since the internal pressure of each single cell is basically the same, the risk of thermal runaway of a single cell due to excessive internal pressure is greatly reduced, thereby improving the safety of the large-capacity battery. If an exhaust valve is added to the first channel, the probability of single cell swelling can be further avoided by opening the exhaust valve regularly. Moreover, the exhaust valve can be opened after the large-capacity battery is aged to discharge the gas generated during the aging process. It can also further improve the cycle life of the large-capacity battery.

[0156] (4) An explosion relief valve can be provided on the first channel. In the event of thermal runaway of a single battery, the thermal runaway flue gas is discharged through the first through hole and the first channel to the external thermal runaway flue gas treatment device for timely treatment, thereby reducing the probability of more serious accidents.

[0157] As shown in Figures 5 and 6, in some embodiments, when the first through hole of the single cell is provided on the side wall or bottom of the single cell, in order to simultaneously satisfy the above four functions (1)(2)(3)(4), a third through hole 21 may be provided on the top of the single cell. Then: a second channel 18 may be provided on the top of the second cylinder 14, and 2N second through holes 11 are arranged on both sides of the second channel 18. In this embodiment, the first channel has two functions (1)(2); the second channel has two functions (3)(4).

[0158] Example 2

[0159] The specific implementation process of the method for manufacturing a large-capacity battery provided in this embodiment is as follows, as shown in FIG1 :

[0160] Step 1: Assembling semi-finished single cells that have not been injected with electrolyte;

[0161] The semi-finished single cell has a structure that is essentially the same as the commercially available aluminum square lithium-ion battery, except that the semi-finished single cell is not injected with electrolyte;

[0162] Step 2: Assemble semi-finished high-capacity batteries;

[0163] Before placing a plurality of semi-finished single cells into a box, or after placing a plurality of semi-finished single cells into the box, a first through hole is formed on the outer shell of each semi-finished single cell, so that the inner cavity of each semi-finished single cell is connected to the inner cavity of the box, and then the poles of each semi-finished single cell extending out of the box are connected in parallel, and then the box is sealed to form a semi-finished high-capacity battery;

[0164] In this step, the first through hole is formed on the outer shell of the semi-finished single battery before the multiple semi-finished single batteries are placed in the box body by directly destroying the outer shell of the semi-finished single battery to form a first through hole on the outer shell;

[0165] After placing multiple semi-finished single cells into a box, a first through-hole is formed in the outer shell of the semi-finished single cells. The semi-finished single cells have a sealing and unpacking mechanism, and a dedicated tool is used to open the sealing and unpacking mechanism on the outer shell of each semi-finished single cell, thereby forming a first through-hole in each semi-finished single cell. The sealing and unpacking mechanism used in this method for the semi-finished single cells is a pull-ring sealing mechanism opened by a pulling rope, as disclosed in Chinese Patent CN218525645U.

[0166] In this step, the process of sealing the box is to ensure that the inside of the box is isolated from the external environment. Therefore, the actual sealed areas are at least the following two:

[0167] 1. When placing semi-finished single batteries, the box must have an open end. Therefore, after all semi-finished single batteries are placed in the box, the open end needs to be sealed;

[0168] 2. Since the poles of each semi-finished single cell in the semi-finished large-capacity battery need to extend out of the top of the box, the area on the top of the box for extending the poles needs to be sealed.

[0169] Step 3: injection and formation;

[0170] The electrolyte is injected into the box so that each single cell is in a unified electrolyte system, and then the formation operation is carried out to complete the production of large-capacity batteries.

[0171] In this process, the specific method of formation is:

[0172] After charging to 3.4V at 0.1C constant current, switch to 3.4V constant voltage charging to a cut-off current of 0.01C and let it rest for 30 minutes;

[0173] Then discharge at 0.1C constant current to 2.5V and let it stand for 30 minutes;

[0174] After charging at a constant current of 0.2C to 3.4V, the battery is then switched to a constant voltage charge of 3.4V to a cutoff current of 0.01C and allowed to rest for 30 minutes. This formation process allows each cell in the high-capacity battery to develop a more stable SEI film, giving it more stable cycling performance.

[0175] The preferred solution of the above method is: a vacuum step is required before liquid injection and formation;

[0176] Since there is a high possibility of generating aluminum chips in the process of forming the first through-hole on the semi-finished single cell by opening the sealing and unpacking mechanism, and impurities may also be introduced into the box during the sealing process (generally sealed by welding), the generation of impurities will inevitably affect the performance of large-capacity batteries. The vacuuming process can remove impurities in the inner cavity of the box and the inner cavity of each semi-finished single cell. After vacuuming, the inner cavity of the box and the inner cavity of the semi-finished single cell are both in a negative pressure state, which can also ensure that during subsequent liquid injection, the electrolyte can smoothly enter the inner cavity of the box and the inner cavity of each semi-finished single cell.

[0177] It should be noted here that the interface used for the above-mentioned vacuuming and liquid injection in step 3 can be one interface on the box body, or it can be two separate interfaces.

[0178] In some embodiments, the large-capacity battery can be aged after formation at an aging temperature of 50° C. and an aging time of 48 hours. After aging, the large-capacity battery can be exhaust-treated to discharge waste gas after formation and reduce the probability of swelling of each single cell of the large-capacity battery.

[0179] Semi-finished single battery

[0180] The specific structures of the semi-finished single battery 100 used in the above method are as follows:

[0181] As shown in Figure 9, the first semi-finished single cell 100 includes a shell 1 and an electrode assembly arranged in the inner cavity of the shell; the electrode assembly here is composed of a positive electrode, a separator, and a negative electrode arranged in sequence, and assembled using a lamination or winding process; the positive electrode of the electrode assembly is connected to the positive electrode column 2 at the top of the shell, and the negative electrode of the electrode assembly is connected to the negative electrode column 3 at the top of the shell; no electrolyte is injected into the inner cavity of the shell; and an explosion-proof membrane is provided on the top of the shell.

[0182] Before the semi-finished single cells are assembled into semi-finished large-capacity batteries, a first through hole communicating with the inner cavity of the semi-finished single cells needs to be opened on the side wall or bottom of the shell using a screwdriver or other sharp tool under specific conditions, so that vacuum can be applied to the inner cavity of each semi-finished single cell during subsequent vacuuming, and it can also ensure that the electrolyte can enter the inner cavity of each semi-finished single cell during liquid injection.

[0183] As shown in Figure 10, the second type of semi-finished single cell 100 includes a shell 1, a sealing and opening mechanism 22 arranged on the side wall or bottom of the shell, and an electrode assembly arranged in the inner cavity of the shell; the electrode assembly here is composed of a positive electrode, a diaphragm, and a negative electrode arranged in sequence, and assembled using a lamination or winding process; the positive electrode of the electrode assembly is connected to the positive electrode column 2 at the top of the shell, and the negative electrode of the electrode assembly is connected to the negative electrode column 3 at the top of the shell; no electrolyte is injected into the inner cavity of the shell 1, and an explosion-proof membrane is provided on the top of the shell 1.

[0184] After the semi-finished single cells are assembled into semi-finished large-capacity batteries, under specific circumstances, the sealing and opening mechanism 22 on the side wall or bottom of the shell is opened by using external force or electrolyte, so that a first through hole is formed on the shell of each single cell, so that the vacuum can be applied to the inner cavity of each semi-finished single cell during the subsequent vacuuming, and it can also ensure that the electrolyte can enter the inner cavity of each semi-finished single cell during liquid injection.

[0185] As shown in FIG11 , the structure of the third semi-finished single cell 100 is similar to that of the second finished single cell, except that the explosion-proof membrane on the top of the outer shell 1 of the semi-finished single cell 100 is replaced by another sealing and unpacking mechanism 22 (that is, the outer shell of the semi-finished single cell has two sealing and unpacking mechanisms 22 ), which is used to form a third through hole on the semi-finished single cell.

[0186] The specific environment mentioned above is preferably an environment with a dew point standard between -25 and 40°C, humidity ≤1%, temperature 23°C±2°C, and cleanliness level 100,000.

[0187] In addition, the shells of the two semi-finished single-cell batteries mentioned above also have two structural forms, as shown in Figures 2 to 4:

[0188] The first type of shell 1 includes a first barrel 5 and an upper cover 6; the first barrel 5 is a structure with an open upper end and a closed lower end; when assembling a semi-finished single battery, the positive and negative poles of the upper cover 6 are first connected to the positive and negative poles of the electrode assembly, and then the upper cover 6 and the electrode assembly are placed as a whole from the upper open end of the first barrel into the first barrel, and finally the upper cover 6 and the open end of the first barrel 5 are welded.

[0189] The second type of shell includes a first barrel 5, an upper cover 6 and a lower cover 7; the first barrel 5 is a structure with open ends at both the upper and lower ends; when assembling a semi-finished single battery, the lower cover 7 is first welded to the lower open end of the first barrel, and then the positive and negative poles of the upper cover 6 are connected to the positive and negative poles of the electrode assembly. Then, the upper cover 6 and the electrode assembly are placed as a whole into the first barrel from the upper open end of the first barrel, and finally, the upper cover 6 and the upper open end of the first barrel 5 are welded.

[0190] If the housing 1 has a sealing and unpacking mechanism 22 , the sealing and unpacking mechanism 22 may be installed on the side wall of the first barrel 5 , the lower cover 7 , and the upper cover 6 before assembling the semi-finished single battery cells.

[0191] It should be emphasized that the outer shell of the semi-finished single battery is made of aluminum material, that is, the first cylinder 5, the upper cover plate 6, and the lower cover plate 7 are all made of aluminum material.

[0192] In some other embodiments, grooves 8 for receiving heat transfer tubes may be provided on the positive and negative electrode posts of the semi-finished single battery cell 100. The heat transfer tubes may be liquid cooling tubes or heat pipes. Since the positive and negative electrode posts are charged, the heat transfer tubes themselves and the medium inside them must be insulated from external devices.

[0193] Large-capacity battery

[0194] Based on the above description of the structure of the semi-finished single cell 100, the structure of the large-capacity battery 200 assembled using the above method and the semi-finished single cell will now be described:

[0195] As shown in Figure 4, the large-capacity battery 200 includes a case 9 and N single cells 10; the N single cells 10 are arranged in parallel in the case 9; a first through hole is provided on the outer shell 1 of each single cell; a liquid filling port (not shown in the figure) is provided on the case 9; a second through hole 11 is provided on the top of the case 9 for leading out the positive and negative poles of each single cell 10, and the top area of ​​the case 9 corresponding to each second through hole 11 is fixedly sealed with the top of the outer shell of the single cell 10 corresponding to the second through hole 11; the electrolyte in each single cell 10 is connected to the electrolyte in the case 9, so that each single cell is in a shared electrolyte system.

[0196] Since the positive and negative electrodes of the single cells 10 in this embodiment are led out of the top of the box, a heat transfer tube can be provided in the groove 8 of the positive electrode of each single cell 10, and a heat transfer tube can be provided in the groove 8 of the negative electrode of each single cell. An external temperature control device is connected to the two heat transfer tubes, thereby achieving temperature control of large-capacity batteries (i.e., heating or cooling large-capacity batteries).

[0197] It should be noted that the positive and negative poles with the grooves 8 may be poles of the semi-finished single battery itself, or may be pole adapters 12 fixedly connected to the poles themselves, with the grooves formed on the pole adapters 12 .

[0198] In this embodiment, the box body 9 is made of aluminum;

[0199] There are two ways to fix and seal the top area of ​​the box body corresponding to each second through hole and the top of the single battery housing corresponding to the second through hole:

[0200] 1. A sealing connector is added between the top area of ​​the case 9 corresponding to the second through hole 11 and the upper cover plate of the single cell 10 corresponding to the second through hole to achieve sealing. Referring to Figures 4 and 11, the sealing connector includes a hollow member 13. The bottom of the hollow member 13 is used to seal with the first area of ​​the single cell 10, and the top of the hollow member 13 is sealed with the second area of ​​the case 9. The first area is the area surrounding any pole on the upper cover plate of any single cell 10; the second area is the area corresponding to any second through hole 11 at the top of the case 9. The area corresponding to the second through hole 11 is the area surrounding any second through hole 11 on the outer surface of the case 9; or the area corresponding to the second through hole 11 is the wall of the through hole. The area surrounding the pole is the area surrounding the insulating gasket on the pole. The insulating gasket is a part on the single cell used to insulate the pole from the upper cover plate of the single cell.

[0201] Second, the area of ​​the box body 9 corresponding to the second through hole 11 and the upper cover plate area around the single cell pole can be directly fixed and sealed by laser welding. This method is generally suitable for cases where the height dimensions of the single cells in the box are relatively consistent.

[0202] Among them, the box structure has the following types:

[0203] 1. Referring to Figures 5 and 11, the box body 9 includes a second cylinder 14, a first cover plate 15, and a second cover plate 16; the top and bottom of the second cylinder 14 are both open, and the first cover plate 15 is sealed and fixed (welded) to the top of the second cylinder 14 and sealed and fixed (welded) to the bottom of the second cylinder 14; 2N second through holes 11 are provided on the first cover plate 15.

[0204] Preferably, in order to allow the electrolyte to smoothly enter the box body 9 and the inner cavity of each semi-finished single cell 100 during the injection process, a first channel 17 extending along the arrangement direction of the single cells and corresponding to the first through hole on the outer shell of each single cell 10 can be opened on the side wall of the second cylinder 14 or the second cover plate 16 according to the position of the first through hole on the outer shell of each single cell. When the first channel 17 is provided, the injection port is arranged in the area of ​​the box body 9 corresponding to any end of the first channel 17. The injection port can simultaneously serve as an interface between the vacuum pumping equipment and the injection equipment.

[0205] Preferably, a second channel 18 may also be provided on the first cover plate 15, and 2N second through holes 11 are arranged on both sides of the second channel 18. When the top of the semi-finished single cell is an explosion-proof membrane (that is, when the above-mentioned second type of semi-finished single cell is used), the second channel 18 covers the explosion-proof membrane of each single cell, and the second channel is used as an explosion-proof channel; when a third through hole is opened on the top of the semi-finished single cell (that is, when the above-mentioned third type of semi-finished single cell is used), the second channel 18 is used to communicate with the inner cavity of each single cell and serve as a gas balance chamber of each single cell; at the same time, an exhaust valve may be provided on the second channel 18. By regularly opening the exhaust valve, the probability of swelling of the single cell can be further avoided. In addition, the exhaust valve can also be opened after aging of the large-capacity battery to discharge the gas generated during the aging process.

[0206] 2. Referring to Figures 6 and 7, the box body 9 includes a second cylinder 14, a third cover plate 19, and a fourth cover plate 20; the front and rear portions of the second cylinder 14 are open, the third cover plate 19 is sealed and fixed (welded) to the front portion of the second cylinder 14, and the fourth cover plate 20 is sealed and fixed (welded) to the rear portion of the second cylinder 14; 2N second through holes 11 are opened on the top of the second cylinder 14.

[0207] Preferably, in order to allow the electrolyte to smoothly enter the box body 9 and the inner cavity of each semi-finished single cell 100 during the injection process, a first channel extending along the arrangement direction of the single cells and corresponding to the first through hole on the outer shell of each single cell can be opened on the side wall or bottom of the second cylinder 14 according to the position of the first through hole on the outer shell of each single cell. When there is a first channel 17, the injection port is set on the third cover plate 19 or the fourth end plate 20, and the injection port can serve as an interface for the vacuum equipment and the injection equipment at the same time.

[0208] Preferably, a second channel 18 may be further provided on the top of the second cylinder, and 2N second through holes 11 are arranged on both sides of the second channel 18. When the top of the semi-finished single battery is an explosion-proof membrane (that is, when the above-mentioned second type of semi-finished single battery is used), the second channel 18 covers the explosion-proof membrane of each single battery, and the second channel 18 is used as an explosion-proof channel; when a third through hole is opened on the top of the semi-finished single battery (that is, when the above-mentioned third type of semi-finished single battery is used), the second channel 18 is used to communicate with the inner cavity of each single battery and serve as a gas balance chamber of each single battery; at the same time, an exhaust valve may be provided in the second channel 18. By regularly opening the exhaust valve, the probability of swelling of the single battery can be further avoided. In addition, the exhaust valve can also be opened after the large-capacity battery is aged to discharge the gas generated during the aging process.

[0209] Example 3

[0210] The specific implementation process of the method for manufacturing a large-capacity battery provided in this embodiment is as follows, as shown in FIG12 :

[0211] As shown in FIG13 , step 1: assembling the battery cell 300;

[0212] A first through hole 4 is formed in the first cylindrical body 5 with an open top. The first through hole 4 can be arranged in the side wall or the bottom of the first cylindrical body 5, and it is only necessary to ensure that the electrolyte in each battery cell can communicate with each other when forming a large-capacity battery.

[0213] The upper cover assembly 23 and the bare cell 24 are connected to form a cell unit 25 by welding. This step is actually to connect the positive electrode of the bare cell 24 to the positive electrode of the upper cover assembly 23 by welding, and the negative electrode of the bare cell 24 to the negative electrode of the upper cover assembly 23 by welding;

[0214] The bare battery cell 24 of the battery cell unit 25 is placed in the first barrel 5, and the periphery of the upper cover assembly 23 is fixed to the periphery of the open end of the first barrel 5 by partial connection, thereby completing the production of the battery cell 300. At this time, no electrolyte is injected into the battery cell 300. The partial connection here can be achieved by spot welding, riveting or screw connection. In order to improve work efficiency and connection reliability, spot welding is used in this embodiment to achieve partial connection.

[0215] As shown in FIG14 , step 2: assembling a large-capacity battery 200;

[0216] Step 2.1: Place multiple battery cells 300 manufactured according to Step 1 into the box 9, ensuring that the inner cavity of each battery cell 300 is connected to the inner cavity of the box 9 through the first through hole 2, and ensuring that the positive electrode column 2 and the negative electrode column 3 of each battery cell 300 extend out of the top of the box 9, and then seal the box 9;

[0217] Step 2.2: inject electrolyte into the box 9 so that each battery cell is in a unified electrolyte system, and then perform a formation operation to complete the production of a large-capacity battery.

[0218] In step 2.1, the process of sealing the box 9 is to ensure that the interior of the box 9 is isolated from the external environment.

[0219] Therefore, there are at least two areas where sealing is actually required:

[0220] 1. When placing battery cells, the box must have an open end. Therefore, after all battery cells are placed in the box, the open end needs to be sealed;

[0221] 2. Since the polarity terminals of each battery cell in the large-capacity battery need to extend out of the top of the box, the area on the top of the box for extending the polarity terminals also needs to be sealed.

[0222] In step 2.2, the specific method of formation is:

[0223] After charging to 3.4V at 0.1C constant current, switch to 3.4V constant voltage charging to a cut-off current of 0.01C and let it rest for 30 minutes;

[0224] Then discharge at 0.1C constant current to 2.5V and let it stand for 30 minutes;

[0225] After charging at a constant current of 0.2C to 3.4V, the battery is then switched to a constant voltage charge of 3.4V to a cutoff current of 0.01C and allowed to rest for 30 minutes. This formation process allows each cell in the high-capacity battery to develop a more stable SEI film, giving it more stable cycling performance.

[0226] The above steps 1 and 2 need to be performed in a specific environment, which is preferably an environment with a dew point standard between -25 and 40°C, humidity ≤1%, temperature 23°C±2°C, and cleanliness level 100,000.

[0227] The manufacturing process of the large-capacity battery also includes the steps of constructing the total positive electrode and the total negative electrode of the large-capacity battery. The steps are specifically: electrically connecting the portion of the positive electrode column of each battery cell extending from the top of the box to form the total positive electrode of the large-capacity battery, and electrically connecting the portion of the negative electrode column of each battery cell extending from the top of the box to form the total negative electrode of the large-capacity battery;

[0228] This step can be performed before or after liquid injection; in this embodiment, since the existing battery manufacturing process requires baking the battery before liquid injection to remove moisture from the bare cell, in this embodiment, the construction step of the total positive electrode and the total negative electrode of the large-capacity battery can be performed before step 2.2 (liquid injection), so that at least one heat exchange tube can be clamped on the total positive electrode and the total negative electrode of the large-capacity battery, and the heat exchange tube can be used to dry and heat each battery cell, and the box can be vacuumed after drying and heating. The heat exchange tube can directly heat each battery cell to control the water content in the bare cell when the large-capacity battery is manufactured. Compared with the traditional vacuum baking method, there is no need for a special vacuum baking box, which reduces the production cost of large-capacity batteries and improves the production efficiency of large-capacity batteries. It is also more conducive to extracting the dried gas in the box and more conducive to liquid injection. The vacuuming during drying can not only promptly discharge the water vapor evaporated from the bare battery cells, but also remove impurities in the inner cavity of the box body 9 and the inner cavity of each battery cell 300. After the vacuuming, the inner cavity of the box body 9 and the inner cavity of each battery cell 300 are both in a negative pressure state, which can also ensure that the electrolyte can smoothly enter the inner cavity of the box body 9 and the inner cavity of each battery cell 300 during the subsequent filling.

[0229] In some embodiments, the large-capacity battery can be aged after formation at an aging temperature of 50° C. and an aging time of 48 hours. After aging, the large-capacity battery can be exhaust-treated to discharge waste gas after formation and reduce the probability of swelling of each single cell of the large-capacity battery.

[0230] battery cells

[0231] As shown in Figures 15 to 18, the battery cell 300 includes a first barrel 5 and a battery cell unit 25; the battery cell unit 25 includes an upper cover assembly 23 and a bare battery cell 24; the bare battery cell 24 is composed of a positive electrode sheet, a separator, and a negative electrode sheet arranged in sequence, and assembled by a lamination or winding process;

[0232] The upper cover assembly 23 includes a cover body 27, a positive electrode column 2 and a negative electrode column 3; the positive electrode column 2 and the negative electrode column 3 are insulated and fixed on the cover body 27; a part of the positive electrode column 2 and the negative electrode column 3 extend out of one side of the cover body 27, and the other part of the positive electrode column 2 and the negative electrode column 3 extend out of the other side of the cover body 27 and are connected to the positive electrode sheet and the negative electrode sheet of the bare battery cell 24; the top of the first cylinder 5 is open, and a first through hole 4 is opened on the side wall or bottom of the first cylinder 5; the bare battery cell 24 is located in the first cylinder 5, and the edge of the cover body 27 and the periphery of the open end of the first cylinder 5 are fixed by spot welding, and the spot welding area is at least two places (preferably spot welding on four sides respectively, the black dots in Figure 5 are spot welding areas), so that there is a gap between the open end of the first cylinder 5 and the upper cover assembly 23; no electrolyte is injected into the inner cavity of the battery cell 300.

[0233] Since there is a first through hole 4 on the first barrel 5 of the battery cell 300, before the battery cell 300 is assembled into the large-capacity battery 200, or during storage and transportation, it is necessary to ensure that the bare battery core of the battery cell 300 is not corroded by the external environment. Therefore, the first through hole 4 of the battery cell 300 can be sealed by thin film heat sealing.

[0234] If the film heat sealing method is not adopted, the storage area of ​​the battery cells needs to be set as a specific environment, and the battery cells need to be placed in a transport warehouse with a specific environment for transportation.

[0235] In order to further improve the production efficiency of large-capacity batteries, the preferred method is to complete the assembly of battery cells and large-capacity batteries in sequence in a clean workshop (a workshop with the above-mentioned specific environment).

[0236] It should be emphasized that the first barrel 5 and the cover body 27 of the battery cell 300 are both made of aluminum, and the first through hole 4 is opened in advance on the bottom and side wall of the first barrel 5 before assembling the battery cell 300.

[0237] The structure of the battery cell 300 is basically the same as that of the existing commercially available square aluminum lithium-ion batteries. The difference is that: no electrolyte is injected into the battery cell 300, and there is no need to set a liquid injection part and an explosion-proof membrane on the upper cover assembly 23. The upper cover assembly 23 and the first cylinder 5 are fixed by spot welding. Based on the above differences, the battery cell of this embodiment can omit the steps of liquid injection, formation, and aging during the production process compared with the existing commercially available square aluminum lithium-ion batteries. At the same time, the welding process of the cover body 27 and the first cylinder 5 is changed from full welding to spot welding, and the welding time is shortened. Since there is a gap between the open end of the first cylinder 5 and the upper cover assembly 23, the airtightness detection process of the battery cell can also be omitted. In summary, the battery cell has the characteristics of simple structure and concise production process, which can reduce its own production cost and thus reduce the cost of large-capacity batteries.

[0238] In this embodiment, a mounting portion for arranging heat exchange tubes is provided on the positive electrode column 2 and the negative electrode column 3. The mounting portion has the following two structural forms:

[0239] 1. As shown in FIG17 , a first groove 28 is provided on each of the positive electrode column 2 and the negative electrode column 3. The cross section of the first groove 28 is preferably C-shaped. The open end of the C-shape has a certain degree of flexibility and can tightly clamp the heat exchange tube therein.

[0240] 2. As shown in FIG18 , a through hole 29 is provided on each of the positive electrode column 2 and the negative electrode column 3 , and the heat exchange tube is passed through the through hole 29 by means of a transition fit or an interference fit;

[0241] Of the two methods mentioned above, the first groove 28 is easier to install the heat exchange tube than the through hole 29 method. The through hole 29 has a larger contact area between the heat exchange tube and the pole than the first groove 28, and has a better heat transfer effect.

[0242] Since the positive electrode column 2 and the negative electrode column 3 are charged, in order to ensure safety, insulation must be maintained between the heat exchange tube 26 and the positive electrode column 2, and between the heat exchange tube and the negative electrode column 3.

[0243] Large-capacity battery

[0244] Based on the above description of the structure of the battery cell 300, the structure of the large-capacity battery 200 assembled using the above method and the battery cell is now described:

[0245] As shown in Figure 19, the large-capacity battery 200 includes a case 9 and N battery cells 300; a first interface 13 is provided on the case 9; a second through hole 11 is provided on the top of the case 9 for leading out the positive electrode column 2 and the negative electrode column 3 of each battery cell; each battery cell 300 is placed side by side in the case 9, and the positive electrode column 2 and the negative electrode column 3 of each battery cell 300 are led out of the second through hole 11, and the second through hole 11 and the corresponding battery cell positive electrode column 2 or negative electrode column 3 are kept sealed; the part of the positive electrode column 2 on each battery cell extending out of the second through hole 11 is electrically connected to constitute the total positive electrode of the large-capacity battery, and the part of the negative electrode column on each battery cell extending out of the second through hole 11 is electrically connected to constitute the total negative electrode of the large-capacity battery; each battery cell 300 is connected to the case 9 through the first through hole 4 on the first cylinder 5, so that each battery cell is in a shared electrolyte system.

[0246] Among them, the box body 9 is made of aluminum material, and the box body structure has the following types:

[0247] 1. Referring to Figures 19 and 20, the housing 9 comprises a shell, a top plate, and a bottom plate. The top and bottom of the shell are both open. The top plate is sealed (welded) to the top of the shell, and the bottom plate is sealed to the bottom of the shell. 2N second through holes 11 are provided on the top plate. In this cylindrical structure, the first interface 30 is installed at either end of the shell.

[0248] 2. Referring to Figures 19 and 20, the housing 9 comprises a shell and two end plates. The front and rear ends of the shell are open, and the two end plates are sealed and fixed (welded) to the ends of the shell. 2N second through holes 11 are provided on the top of the shell. In this cylindrical structure, the first interface 30 is mounted on one of the two end plates.

[0249] The first interface 30 has the following functions:

[0250] It can be connected to the fluid injection and replacement equipment to be used for fluid injection and replacement of large-capacity batteries. It can also be connected to the vacuum equipment to be used for vacuuming large-capacity batteries. An explosion relief valve can also be set, and of course a sealing plug can also be installed.

[0251] In this embodiment, the box body also includes a second interface 31, which is arranged at a position of the end plate of the box body 9 near the top of the box body 9 or at the top of the box body 9. An exhaust valve is provided on the second interface 31. The exhaust valve can regularly discharge the gas generated in the large-capacity battery during the operation of the large-capacity battery, thereby reducing the probability of swelling of each battery cell and further reducing the probability of thermal runaway of the large-capacity battery. Moreover, the exhaust valve can also be opened after the large-capacity battery ages to discharge the gas generated during the aging process, thereby further improving the cycle life of the large-capacity battery.

[0252] [Corrected 14.10.2024 according to Rule 91] Furthermore, in this embodiment, as shown in FIG20 , two pads 32 are provided on the bottom inner surface of the housing 9 , extending in the direction in which the battery cells are arranged. An electrolyte channel 33 is formed between the two pads 32 , and the electrolyte channel 33 communicates with the electrolyte area of ​​each battery cell. This pad design has two advantages:

[0253] 1. When the pad 32 contacts the bottom surface of the battery cell 300, it is easier to ensure flatness than when the inner surface of the bottom of the box body directly contacts the bottom surface of the battery cell. That is, the height of the polarity terminals of the battery cell when they extend out of the top plate can remain basically consistent, and the polarity terminals of the battery cell can reliably extend out of the top of the box body.

[0254] 2. The electrolyte channel 33 formed between the two pads 32 can improve the continuity of the electrolyte level between each battery cell (avoiding the occurrence of electrolyte interruption).

[0255] Since the positive electrode column 2 and the negative electrode column 3 of the battery cell 300 in this embodiment are led out from the top of the box body 9 and the mounting parts of the heat exchange tube 26 are provided on the positive electrode column and the negative electrode column; therefore, the total positive electrode and the total negative electrode of the large-capacity battery are heat-exchanged with the external temperature control device through at least one heat exchange tube, thereby realizing temperature control of the large-capacity battery (that is, the large-capacity battery can be heated or cooled).

[0256] As shown in FIG19 , the heat exchange tube 26 can be specifically arranged in the following ways:

[0257] 1. An aluminum tube is bent into a U-shaped structure, and two parallel tube sections are used to match the total positive electrode and total negative electrode of the large-capacity battery, thereby realizing heat exchange between each battery cell and the external temperature control device. The liquid inlet and liquid outlet of the aluminum tube are located on the same side; the transmission medium in the aluminum tube can be water, insulating oil or fluorinated liquid; or two aluminum tubes can be used to match the total positive electrode and total negative electrode respectively.

[0258] 2. Two cored heat pipes are used to cooperate with the total positive electrode and the total negative electrode respectively, so as to realize the heat exchange between each battery cell and the external temperature control device. The cored heat pipe is an evaporation-condensation type heat exchange device, which realizes heat transfer by the state change of the working fluid in the pipe.

[0259] Since the heat transfer effect of a cored heat pipe is affected by its length, its use is limited when a large-capacity battery has a large number of battery cells (i.e., a large-capacity battery has a long length). Therefore, in this embodiment, aluminum tubes are preferably used as heat transfer tubes. If insulation between the heat transfer tubes and the poles can be effectively ensured, water can be preferably used as the heat transfer medium flowing in the aluminum tubes in consideration of heat transfer efficiency and cost.

[0260] In this embodiment, there are three ways to maintain sealing between the second through hole 11 and the corresponding positive electrode column or negative electrode column of the battery cell:

[0261] 1. As shown in Figure 16, a hollow member 34 is added between the top area of ​​the box body 9 corresponding to the second through hole 11 and the battery cell upper cover assembly corresponding to the second through hole 11 to achieve sealing. The hollow member 34 is mounted on the polarity terminal of the battery cell 300. The bottom of the hollow member 34 is used for welding to the upper cover assembly of the battery cell, and the top of the hollow member is welded to the box body;

[0262] Second, the area of ​​the box body 9 corresponding to the second through hole 11 and the area around the polarity terminal of the upper cover assembly of the battery cell can be directly welded to achieve fixed sealing. This method is generally suitable for cases where the height dimensions of the individual batteries in the box are relatively consistent.

[0263] 3. An insulating sealant layer that does not react with the electrolyte can be directly poured into the gap between the second through hole 11 and the polarity terminal of the battery cell.

Claims

1. A method for manufacturing a large-capacity battery, characterized in that: The following steps are involved: Assembling semi-finished single cells that have not been injected with electrolyte; Assembling semi-finished high-capacity batteries; Put a plurality of semi-finished single cells into a box, wherein the inner cavity of each semi-finished single cell is connected to the inner cavity of the box through at least one first through hole, seal the box, and connect the poles of each semi-finished single cell extending out of the box in parallel, thereby forming a semi-finished large-capacity battery; The first through hole is preset on the outer shell of the semi-finished single battery, or the first through hole is formed on the outer shell of each semi-finished single battery before placing the plurality of semi-finished single batteries into the box, or after placing the plurality of semi-finished single batteries into the box; Injection and formation; Inject electrolyte into the semi-finished large-capacity battery so that each single cell is in a unified electrolyte system, and then perform the formation operation to complete the production of the large-capacity battery.

2. The method for manufacturing a large-capacity battery according to claim 1, characterized in that: The method also includes the step of evacuating the semi-finished large-capacity battery.

3. A method for manufacturing a large-capacity battery according to claim 1 or 2, characterized in that: The method also includes the step of aging the large-capacity battery after formation.

4. A semi-finished single cell, characterized in that: A method for manufacturing a large-capacity battery as claimed in any one of claims 1 to 3; The semi-finished single cell comprises a housing, a positive electrode column, a negative electrode column and an electrode assembly; The positive electrode column and the negative electrode column are insulated and fixed to the top plate of the shell; a part of the positive electrode column and the negative electrode column extends out of the top of the shell; another part of the positive electrode column and the negative electrode column extends into the shell and is connected to the electrode assembly arranged in the shell; no electrolyte is injected into the shell; at least one first through hole is arranged on the shell.

5. A semi-finished single cell according to claim 4, characterized in that: The top of the housing is provided with at least one first through hole.

6. A semi-finished single cell according to claim 4, characterized in that: At least one first through hole is arranged on the bottom or the side wall of the shell, and a third through hole is arranged on the top of the shell.

7. A semi-finished single cell, characterized in that: A method for manufacturing a large-capacity battery as claimed in any one of claims 1 to 3; The semi-finished single cell comprises a housing, a positive electrode column, a negative electrode column and an electrode assembly; The positive electrode column and the negative electrode column are insulated and fixed to the top plate of the shell; a part of the positive electrode column and the negative electrode column extends out of the top of the shell; another part of the positive electrode column and the negative electrode column extends into the shell and is connected to the electrode assembly arranged in the shell; no electrolyte is injected into the shell.

8. A semi-finished single cell according to claim 7, characterized in that: At least one sealing and opening mechanism is arranged on the shell.

9. A semi-finished single cell according to claim 8, characterized in that: There are two sealing and unpacking mechanisms, one of which is arranged on the side wall in the thickness direction of the shell or on the bottom of the shell, and the other is arranged on the top of the shell.

10. A method for manufacturing a large-capacity battery, characterized in that: The following steps are involved: Assembling battery cells; A first through hole is formed on the first cylinder body with an open top; Connect the upper cover assembly and the bare battery cell into a battery cell unit by welding; The bare battery cell of the battery cell unit is placed in the first cylinder, and the periphery of the upper cover assembly is fixed to the periphery of the open end of the first cylinder by partial connection, ensuring that there is a gap between the periphery of the upper cover assembly and the periphery of the open end of the first cylinder, thereby completing the production of the battery cell; Assemble large capacity batteries; Put multiple battery cells into the box body, ensure that the inner cavity of each battery cell is connected with the inner cavity of the box body through the first through hole, and ensure that the positive electrode column and the negative electrode column of each battery cell extend out of the top of the box body, and then seal the box body; Inject electrolyte into the box so that each battery cell is in a unified electrolyte system, and then perform the formation operation to complete the production of large-capacity batteries.

11. The method for manufacturing a large-capacity battery according to claim 10, characterized in that: It also includes electrically connecting the portion of the positive pole in each battery cell that extends out of the top of the box to form a total positive pole of the large-capacity battery, and electrically connecting the portion of the negative pole in each battery cell that extends out of the top of the box to form a total negative pole of the large-capacity battery.

12. The method for manufacturing a large-capacity battery according to claim 11, characterized in that: The method also includes the steps of clamping at least one heat exchange tube on the total positive electrode and the total negative electrode of the large-capacity battery before liquid injection, and drying and heating each battery cell through the heat exchange tube, and evacuating the box body during the drying and heating process.

13. A method for manufacturing a large-capacity battery according to any one of claims 10 to 12, characterized in that: The method also includes the step of aging the large-capacity battery after formation.

14. A battery cell, used for manufacturing a large-capacity battery according to claim 10, characterized in that: It includes a battery cell unit and a cylinder; The battery cell unit includes an upper cover assembly and a bare battery cell; The upper cover assembly includes a cover body, a positive electrode column and a negative electrode column; The positive electrode column and the negative electrode column are insulated and fixed on the cover body; a part of the positive electrode column and the negative electrode column extends out of one side of the cover body, and another part of the positive electrode column and the negative electrode column extends out of the other side of the cover body and is connected to the bare battery cell; The top of the first cylinder is open, and a first through hole is formed on the side wall or the bottom of the first cylinder; The bare battery cell is located in the cylinder, and the edge of the cover body and the periphery of the open end of the first cylinder are fixed by partial connection, so that a gap is formed between the open end of the first cylinder and the upper cover.

15. A battery cell according to claim 14, characterized in that: The positive pole and the negative pole are provided with mounting portions for arranging heat exchange tubes.

16. A large capacity battery, characterized in that: A box body and a plurality of battery cells according to claim 14; The box body is provided with a first interface; the top of the box body is provided with a second through hole for leading out the positive pole and the negative pole of each battery cell; The battery cells are placed side by side in the box, and the positive pole and negative pole of each battery cell are led out of the second through hole, and the second through hole and the corresponding positive pole or negative pole of the battery cell are kept sealed; The part of the positive electrode post on each battery cell extending out of the second through hole is electrically connected to form the total positive electrode of the large-capacity battery, and the part of the negative electrode post on each battery cell extending out of the second through hole is electrically connected to form the total negative electrode of the large-capacity battery; Each battery cell is connected to the box body through the first through hole on the cylinder body, so that each battery cell is in a shared electrolyte system.

17. A large capacity battery according to claim 16, characterized in that: The box body comprises a shell and end plates fixedly sealed at two ends of the shell; the first interface is arranged on the end plates.

18. A large capacity battery according to claim 16 or 17, characterized in that: The box body also includes a second interface, which is arranged at a position of an end plate of the box body close to the top of the box body or at the top of the box body.

19. A large capacity battery according to claim 18, characterized in that: The total positive electrode and the total negative electrode perform heat exchange with an external temperature control device through at least one heat transfer tube.

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