Liquid injection method of soft package battery cell

Abstract

The invention provides a liquid injection method of a soft package battery cell, which comprises the following steps: primary liquid injection, formation after the primary liquid injection, and secondary liquid injection after the formation, the opening of an air bag of the soft package battery cell is sealed before the formation and before or after the primary liquid injection, and the air bag is provided with a liquid supplementing device through the sealing, the gas bag is used for accommodating gas generated by formation, and after formation, the electrolyte is supplied to the gas bag through the liquid supplementing device so as to enable the electrolyte to enter the naked battery cell of the soft package battery cell, so that secondary liquid injection is realized. The liquid injection method of the soft package battery cell provided by the invention is high in realizability and simple in implementation process.

Description

Technical Field

[0001] The present application relates to the field of secondary batteries, and more specifically, to a method for injecting liquid into a soft-pack battery cell. Background Art

[0002] In the field of new energy technology, the development of bare cells has received more and more attention. With the development and maturity of technology, the application of soft-pack batteries has become more and more extensive. In the production process of soft-pack batteries, the bare cells are usually placed in an air bag to form the initial soft-pack cells. Further, the soft-pack cells (i.e., the bare cells in the air bag) are injected with electrolyte or vented from the opening of the air bag. In the process of injecting or venting the soft-pack cells, one side of the air bag is usually opened, and the electrolyte is injected into the air bag through the opening, so that the bare cells are immersed in the electrolyte. Gas will be generated after the electrolyte reacts with the bare cells, and these gases will also be discharged from the opening.

[0003] The above method can be used for a single injection of a soft-pack battery. However, due to the increasingly high performance requirements, it is necessary to perform a secondary injection of the soft-pack battery to improve the key performance of the bare cell, such as power, cycle life, storage life, etc., so as to achieve performance that cannot be achieved by the first injection, such as high power, high cycle life, high storage life, etc. However, due to the particularity of the secondary injection, the soft-pack battery faces many process challenges in order to achieve this. For example, the secondary injection may cause the air bag to close and the exhaust cannot be exhausted, which makes the process complicated and difficult to implement in an industrialized manner.

[0004] Although some prior arts disclose secondary injection of soft-pack batteries, it still requires a relatively complicated process and cannot be implemented on the original production line or equipment, which also makes secondary injection difficult to implement. Therefore, there is an urgent need for a method for injecting liquid into soft-pack batteries that is highly feasible and has a simple implementation process. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a method for injecting liquid into a soft-pack battery cell with high feasibility and simple implementation process.

[0006] To achieve the above-mentioned purpose, an embodiment of the present application provides a method for injecting liquid into a soft-pack battery cell, comprising: a primary injection, formation after the primary injection, and a secondary injection after the formation, wherein, before the formation and before or after the primary injection, the opening of the air bag of the soft-pack battery cell is sealed, and the air bag is provided with a liquid replenishing device through the sealing, wherein the air bag is used to contain the gas generated by the formation, and after the formation, the electrolyte is provided to the air bag through the liquid replenishing device so that the electrolyte enters the bare cell of the soft-pack battery cell, thereby realizing the secondary injection.

[0007] In some embodiments, the rehydration device is a sealed cavity disposed in the air bag and containing an electrolyte. After formation, the sealed cavity allows the electrolyte to flow out of the sealed cavity and enter the bare battery cell through the air bag.

[0008] In some embodiments, the liquid replenishing device is a liquid injection hole arranged at the sealing position, wherein after formation, the electrolyte is injected into the air bag through the liquid injection hole, and the electrolyte flows through the air bag and enters the bare battery cell.

[0009] In some embodiments, after a single injection and before formation, a weak portion is provided between the opening of the air bag and the bare battery cell to form an independent chamber in the air bag, electrolyte is loaded into the independent chamber from the opening, and then the opening is sealed to place the electrolyte in the independent chamber, thereby forming a closed cavity containing electrolyte in the air bag, wherein the closed cavity is squeezed to break the weak portion, so that the electrolyte flows out from the weak portion and is injected into the bare battery cell through the air bag.

[0010] In some embodiments, during the secondary liquid filling process, the sealing ensures that the airbag is always in an airtight sealed state.

[0011] In some embodiments, before a liquid injection, the opening of the air bag is sealed, and a liquid injection hole is provided at the sealing position, wherein the connection between the air bag and the outside of the soft-pack battery cell is achieved through the liquid injection hole.

[0012] In some embodiments, during the secondary injection process, the injection hole is fixed by a seal.

[0013] In some embodiments, after sealing and before formation, the bare cell of the soft-pack cell is injected with liquid once through the injection hole.

[0014] In some embodiments, after the secondary injection, the outer shell of the soft-pack battery cell is heat-sealed to isolate the air bag from the bare battery cell, and then the air bag is cut off.

[0015] In some embodiments, the soft-pack battery cell is a soft-pack lithium-ion battery cell.

[0016] The beneficial technical effects of this application are:

[0017] 1. Make the secondary injection process of soft-pack batteries simple, and can be transformed on the original primary injection production line or equipment, with high feasibility;

[0018] 2. The method provided in this application can make it possible for soft-pack batteries to be refilled as easily as hard-shell batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figures 1A to 1E It is a schematic diagram of injecting liquid into a soft-pack battery cell in Example 1 of the present application.

[0020] Figure 2 and Figure 3 This is a schematic diagram of injecting liquid into a soft-pack battery cell in Example 2 of the present application.

[0021] Figure 4 It is an enlarged view of the liquid injection hole of Example 2 of the present application. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. It should be understood that the following description of the present application with reference to the accompanying drawings is only illustrative and not restrictive. The various different embodiments can be combined with each other to form other embodiments not shown in the following description. In addition, the various directional terms used in the following description are also only illustrative and do not constitute any limitation to the present application.

[0023] At present, soft-pack batteries are used to power electrical devices such as new energy vehicles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys or electric tools. In the preparation process of soft-pack batteries, usually after placing the bare battery cell in the air bag, the corresponding soft-pack battery cell is injected to form the final soft-pack battery cell, and then the corresponding soft-pack battery is formed. It can be seen that the performance of the soft-pack battery cell is crucial. Therefore, it is necessary to perform a secondary injection after the soft-pack battery cell is injected once to achieve the corresponding pursuit of higher performance. Based on this, the present application will provide a method for injecting soft-pack batteries with high feasibility and simple implementation process.

[0024] Usually, first provide Figure 1E or Figure 3 The bare cell 104 of the soft-pack battery 100 shown is made of a positive electrode sheet, a separator and a negative electrode sheet commonly used in the art, which are wound or laminated in sequence. Specifically, the positive electrode sheet may include a positive current collector and a positive active material layer coated on at least one surface of the positive current collector. The positive active material used in the positive active material layer may be selected from, but is not limited to, lithium cobalt oxide (LiCoO 2 ), lithium nickel manganese cobalt ternary material (NCM), lithium iron phosphate (LiFePO 4 ), lithium iron manganese phosphate (LiFeMnPO 4 ), lithium manganese oxide (LiMn 2 O 4 ), lithium nickel oxide (LiNiO 2 ), lithium cobalt phosphate (LiCoPO 4) and one or more of their combinations, the above positive electrode active materials include positive electrode active materials that have been doped or coated in the prior art, and the positive electrode collector can be aluminum foil. Similarly, the negative electrode plate includes a negative electrode collector and a negative electrode active material layer coated on at least one surface of the negative electrode collector, and the negative electrode active material used in the negative electrode active material layer may include but is not limited to at least one of silicon material, carbon, and graphite. For example, it can be selected from one or more of natural graphite, artificial graphite, mesophase carbon microbeads (referred to as MCMB), hard carbon, soft carbon, silicon, silicon oxide compounds, silicon carbon compounds, silicon nitrogen compounds, and silicon alloys, and the negative electrode collector can be copper foil. In order to prevent short circuits, a separator is usually provided between the positive and negative electrodes. For example, a separator comprising a substrate layer and a surface treatment layer; the substrate layer is a non-woven fabric, a film or a composite film having a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate, and polyimide. Specifically, polypropylene porous film, polyethylene porous film, polypropylene non-woven fabric, polyethylene non-woven fabric, polypropylene-polyethylene-polypropylene porous composite film can be selected. A surface treatment layer is provided on at least one surface of the substrate layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by a mixed polymer and an inorganic substance. However, those skilled in the art will understand that the positive active material, the negative active material and the separator of the present application can be other suitable materials.

[0025] Next, in Figure 1A or Figure 2 After the bare battery cell 104 is placed in the aluminum-plastic film (including the air bag 101 and the shell 104S), it is injected with liquid accordingly, as follows:

[0026] like Figures 1A to 3 As shown, a method for injecting liquid into a soft-pack battery cell is provided, including: a primary injection, forming after the primary injection, and a secondary injection after the forming, wherein before the forming, the opening 101O of the air bag 101 of the soft-pack battery cell 100 for accommodating the gas generated by the forming is sealed 102, and the air bag 101 is provided with a liquid replenishing device 103 through the sealing 102, and after the forming, the electrolyte is provided to the air bag 101 through the liquid replenishing device 103 so that the electrolyte enters the bare battery 104 of the soft-pack battery cell 100, thereby realizing the secondary injection. That is, in the present application, a liquid replenishing device 103 is added directly when the opening of the air bag 101 is sealed 102, so as to realize the secondary injection with a simple process.

[0027] In some embodiments of the present application, Figures 1A to 1E As shown, the liquid replenishing device 103 is a closed cavity 103A (see FIG. 1 ) disposed in the air bag 101 and containing an electrolyte. Figure 1B), after formation, the electrolyte flows out of the sealed cavity 103A by squeezing the sealed cavity 103A, and enters the bare battery cell 104 through the air bag 101 provided with the sealed cavity 103A. In the embodiment, after the first injection and before formation, a weak portion 106 is provided between the opening 101O of the air bag 101 and the bare battery cell 104 to form an independent chamber 103A' in the air bag 101 (see Figure 1A ), the electrolyte is loaded into the independent chamber 103A' from the opening 101O, and then the opening 101O is sealed 102 to place the electrolyte in the independent chamber 103A', thereby forming a closed cavity 103A containing the electrolyte disposed in the air bag 101. When performing the secondary liquid injection, the closed cavity 103A is squeezed to break the weak portion 106, so that the electrolyte flows out from the weak portion 106 and is injected into the bare battery 104 through the air bag 101 provided with the closed cavity 103A. That is, in the present embodiment, when the air bag 101 is sealed 102 on the bare cell 104 of the soft-pack battery 100, a heat-sealing process for forming a weak portion 106 is added to form an independent chamber 103A'. After the first injection, the electrolyte that needs a second injection is set in the independent chamber 103A', thereby forming a closed cavity 103A, and the weak portion 106 on the inner side of the closed cavity 103A is weaker than the seal 102 on the outer side; after the formation is completed, the weak portion 106 on the inner side of the closed cavity 103A is destroyed by extrusion, so that the electrolyte injected for the second time can then enter the interior of the bare cell 104 (such as entering the interior of the bare cell 104 through the corresponding air bag 101), thereby achieving the purpose of the second injection. The secondary liquid injection performed by this method can improve various performances of the bare battery cell 104, such as power, cycle life, storage life, etc. At the same time, the liquid injection method provided in the present application has a simple process and can be modified on the original single-injection production line or equipment to achieve secondary liquid injection, which is highly feasible.

[0028] In the above embodiment, during the secondary liquid injection process, the seal 102 keeps the air bag 101 in an airtight sealed state, that is, during the entire secondary liquid injection process, the seal 102 is not damaged.

[0029] In some other embodiments of the present application, see Figure 2 , the liquid replenishing device 103 is a liquid injection hole 103B arranged at the position of the seal 102, wherein, after formation, the electrolyte is injected into the air bag 101 through the liquid injection hole 103B, and the electrolyte flows through the air bag 101 and enters the bare battery 104. It is worth noting that before the first liquid injection, the opening of the air bag 101 is sealed 102, and a liquid injection hole 103B is arranged at the position of the seal 102. In this embodiment, the communication between the air bag 101 and the outside of the soft-pack battery 100 is realized through the liquid injection hole 103B. See Figure 4 , Figure 4 An enlarged view of the injection hole 103B is shown. Figure 4 As can be seen in the figure, the injection hole 103B is made of a base 103B1, a slot 103B2 set on the base 103B1, and a plug 103B3 matching the slot 103B2. In some embodiments, the slot 103B2 is formed integrally with the base 103B1. In some embodiments, the connection between the air bag 101 and the outside of the soft-pack battery 100 is controlled by controlling the insertion and removal of the plug 103B3. In some embodiments, the slot 103B2 and the base 103B1 are both formed of a resin material (such as polyethylene terephthalate (PET)), and the plug 103B3 can be formed of the same resin material as the slot 103B2 and the base 103B1, or it can be formed of other sealing materials that can provide sealing. In some embodiments, the base 103B1 of the injection hole 103B is set at the position of the seal 102, while the slot 103B2 and the plug 103B3 protrude higher than the position of the corresponding seal 102. In some embodiments, the base 103B1 of the injection hole 103B and a portion of the slot 103B2 thereon are fixed together at the position of the seal 102 .

[0030] In the above embodiment, during the secondary liquid injection process, the liquid injection hole 103B is always fixed by the seal 102, that is, during the entire secondary liquid injection process, the seal 102 is not damaged. In addition, in the above embodiment, after the seal 102 and before the formation, the bare cell 104 of the soft-pack cell 100 is injected once through the liquid injection hole 103B.

[0031] In the above embodiment, the liquid injection hole 103B is formed so that the soft-pack battery cell 100 can be easily filled with liquid twice like a hard-shell battery cell.

[0032] In some embodiments of the present application, the liquid injection method of the soft-pack battery provided by the present application performs heat sealing 105 on the shell 104S of the soft-pack battery 100 after the secondary liquid injection to separate the air bag 101 from the bare battery 104, and then cuts off the air bag 101. In addition, in some embodiments of the present application, the soft-pack battery 100 is a soft-pack lithium-ion battery, and the shell 104S of the soft-pack lithium-ion battery is made of an aluminum-plastic film, and the air bag 101 is a part of the aluminum-plastic film.

[0033] Furthermore, if Figures 2 to 4As shown, in some embodiments of the present application, the bare cell 104 of the soft-pack battery 100 has two tabs 108, which extend along the direction in which the bare cell 104 extends on the same side of the bare cell 104, and are arranged side by side along a first direction perpendicular to the direction in which the bare cell 104 extends, wherein the portion of the tab 108 extending from the bare cell 104 and blocked by the shell 104S of the soft-pack battery 100 is shown by a dotted line. In addition, in some embodiments, the shell 104S of the soft-pack battery 100 is formed with an air bag 101 and a cell area 107 for accommodating the bare cell 104, and from Figures 2 to 4 It can be seen that the airbag 101 and the battery cell area 107 are arranged side by side along a direction parallel to the first direction. In some embodiments, the polarity of the tab 108 can be set according to a common method in the art or according to requirements.

[0034] In the above embodiment, the electrolyte may be a commonly used electrolyte in the art, and may include a lithium salt and a non-aqueous solvent. The lithium salt includes LiPF 6 , LiBF 4 、LiAsF 6 etc., and the non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents or a combination thereof.

[0035] In the above embodiment, the seal 102 and heat seal 105 used in the present application use the sealing equipment commonly used in the art, and the seal 102 and heat seal 105 are performed under the conditions commonly used in the art, such as heat sealing at a heat sealing temperature between 200°C and 250°C and a heat sealing pressure of 1.0MPa-1.2MPa for 10-15s. As for the weak portion 106 in the above embodiment, the weak portion 106 is formed under the conditions of the corresponding heat sealing pressure and heat sealing temperature lower than the seal 102 and heat seal 105, such as heat sealing at a heat sealing temperature between 150°C and 180°C and a heat sealing pressure of 0.7MPa-0.9MPa for 5-10s, so that the weak portion 106 can be squeezed out later. In some embodiments, the heat sealing temperature between 200°C and 250°C is specifically, including but not limited to 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, and the heat sealing pressure of 1.0MPa-1.2MPa is specifically, including but not limited to 1.0MPa, 1.1MPa or 1.2MPa, and the heat sealing 10-15s is specifically, including but not limited to heat sealing 10s, 11s, 12s, 13s, 14s or 15s. Similarly, the heat sealing temperature between 150°C and 180°C is specifically, including but not limited to 150°C, 160°C, 170°C or 180°C, the heat sealing pressure of 0.7MPa-0.9MPa is specifically, including but not limited to 0.7MPa, 0.8MPa or 0.9MPa, and the heat sealing 5-10s is specifically, including but not limited to heat sealing 5s, 6s, 7s, 8s, 9s or 10s.

[0036] Furthermore, in the above and following embodiments, Figures 1A to 3 The seals created by the seal 102, the heat seal 105 and the weakened portion 106 are all shown.

[0037] The following first describes a method for preparing the bare battery cell 104 and the electrolyte.

[0038] (1) Preparation of positive electrode:

[0039] The positive electrode active material (LiNi 0.8 Co 0.1 Mn 0.1 O 2 ), polyvinylidene fluoride as an adhesive and acetylene black as a conductive agent are mixed in a mass ratio of 98:1:1, and an appropriate amount of solvent N-methylpyrrolidone (NMP) is added, and the positive electrode slurry is stirred by a vacuum mixer until the positive electrode slurry is uniform and transparent to obtain a positive electrode slurry. The positive electrode slurry is evenly coated on a 16μm aluminum foil current collector, and then the current collector is dried at room temperature and transferred to an oven at 80℃~120℃ for 6h, and then cold pressed and cut to obtain a positive electrode sheet.

[0040] (2) Preparation of negative electrode:

[0041] The negative electrode active material graphite, the conductive agent acetylene black, the thickener sodium carboxymethyl cellulose and the adhesive styrene butadiene rubber are mixed in a mass ratio of 97:1:1:1, and after adding deionized water, the negative electrode slurry is obtained under the action of a vacuum mixer; the negative electrode slurry is evenly coated on an 8μm copper foil current collector; after drying at room temperature, it is transferred to an oven for drying, and then cold pressed and cut to obtain negative electrode sheets.

[0042] (3) Preparation of electrolyte:

[0043] The organic solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), wherein the volume ratio of EC, EMC and DEC is 20:20:60. In an argon atmosphere glove box with a water content of <10 ppm, a fully dried lithium salt (LiPF 6 ) is dissolved in the above organic solvent and mixed evenly to obtain an electrolyte, wherein LiPF 6 The concentration is 1 mol / L.

[0044] (4) Preparation of isolation membrane:

[0045] A 12μm thick polypropylene isolation film was selected.

[0046] (5) Preparation of bare battery cell 104:

[0047] The positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in sequence, with the separator being placed between the positive and negative electrode sheets to play an isolating role, thereby manufacturing a bare battery cell 104 .

[0048] The above electrolyte is for standby use. In addition, the electrolytes used in the following examples are all the electrolytes prepared as above.

[0049] The following is a description of the liquid injection method for the soft-pack battery provided in the present application in conjunction with specific embodiments. Those skilled in the art will understand that the preparation method described in the present application is only an example, and any other suitable liquid injection method is within the scope of the present application.

[0050] Example 1

[0051] (1) One-time injection:

[0052] See also Figure 1A , the bare cell 104 of the soft-packed cell 100 is placed in the housing (aluminum-plastic film) 104S, and transferred to a vacuum oven for drying (such as at a temperature of 120°C). Afterwards, the electrolyte is injected once through the air bag 101. In this embodiment, the soft-packed cell 100 is a soft-packed lithium-ion cell, and the injection is performed using a method commonly used in the art. In this embodiment, the air bag 101 is a part of the housing (aluminum-plastic film) 104S.

[0053] (2) Forming a fluid replenishment device:

[0054] See also Figure 1A and Figure 1B After one injection is completed, the Figure 1A The weak portion 106 shown in the figure is provided between the opening 101O of the air bag 101 and the bare battery cell 104 to form an independent chamber 103A' in the air bag 101, and the electrolyte to be injected for the second time is injected into the independent chamber 103A' from the opening 101O, and then the opening 101O is sealed 102 to set the electrolyte to be injected for the second time in the independent chamber 103A', thereby forming a closed chamber 103A containing the electrolyte in the air bag 101, as shown in FIG. Figure 1B After the closed cavity 103A is formed, Figure 1B The structure shown was synthesized.

[0055] (3) Secondary injection:

[0056] See also Figure 1C After the formation, that is, after the formation is completed, a roller or other device (such as a roller press) is used to squeeze the electrolyte in the sealed cavity 103A that needs to be injected for the second time to break the weak portion 106, so that the electrolyte flows out of the sealed cavity 103A and enters the bare battery cell 104 through the air bag 101. In this embodiment, the weak portion 106 on the inner side of the sealed cavity 103A is destroyed by squeezing, so that the electrolyte injected for the second time can enter the bare battery cell 104, thereby achieving the purpose of the second injection.

[0057] from Figures 1A to 1C It can be seen that during the secondary liquid injection process, the seal 102 keeps the air bag 101 in an airtight sealed state and is not damaged during the entire secondary liquid injection process.

[0058] (4) Forming soft-pack batteries:

[0059] See also Figure 1D to Figure 1E After the second injection, the soft pack battery cell 100 (see Figure 1D ) is heat-sealed 105 to separate the air bag 101 from the bare battery cell 104, and then the air bag 101 is cut off to obtain Figure 1E The soft-pack battery cell 100 shown is a soft-pack lithium-ion battery cell.

[0060] In the above embodiment, the secondary liquid injection performed by the above method can improve various performances of the bare battery cell 104, such as power, cycle life, storage life, etc. At the same time, the liquid injection method provided in the present application has a simple implementation process and can be modified on the original single-injection production line or equipment to achieve secondary liquid injection, which has high feasibility.

[0061] Example 2

[0062] (1) Forming a fluid replenishment device:

[0063] See also Figure 2 , the soft pack battery cell 100 (see Figure 4 ) is placed in a housing (aluminum plastic film) 104S and transferred to a vacuum oven for drying (such as at a temperature of 120°C). Figure 2 When the airbag 101 is inserted into the sealing opening 102 (not shown), the injection hole 103B is simultaneously arranged at the position of the sealing opening 102, so as to achieve the purpose of connecting the airbag 101 with the outside of the soft-pack battery cell 100. In this embodiment, see Figure 4 , the slot 103B2 and the base 103B1 are formed integrally and are both made of a resin material commonly used in the art, such as polyethylene terephthalate (PET). In this embodiment, the plug 103B3 is also formed of the same resin material as the slot 103B2 and the base 103B1, and may also be formed of other sealing materials that can provide sealing. In this embodiment, the base 103B1 of the injection hole 103B is set at the position of the seal 102, while the slot 103B2 and the plug 103B3 protrude higher than the corresponding seal 102. Figure 2 It can be seen that in this embodiment, the connection between the air bag 101 and the outside of the soft-pack battery 100 is controlled by controlling the plug 103B3 to be plugged in and out. In this embodiment, the soft-pack battery 100 is a soft-pack lithium-ion battery.

[0064] (2) One-time injection:

[0065] The electrolyte required for the primary injection is injected into the air bag 101 through the injection hole 103B, and the electrolyte flows through the air bag 101 and enters the bare battery 104. After the primary injection, the resulting structure is formed.

[0066] (3) Secondary injection:

[0067] After the formation, the electrolyte required for the secondary injection is injected into the air bag 101 through the injection hole 103B, and the electrolyte also flows through the air bag 101 and enters the bare battery 104. It can be seen that in this embodiment, the electrolyte required for the secondary injection is injected into the bare battery 104 through the injection hole 103B. In this embodiment, during the secondary injection process, the injection hole 103B is always fixed by the seal 102, that is, the seal 102 is not damaged.

[0068] (4) Forming soft-pack batteries:

[0069] See also Figures 2 to 3 After the second injection, the soft pack battery cell 100 (see Figure 3 ) is heat-sealed 105 to separate the air bag 101 from the bare battery cell 104, and then the air bag 101 is cut off to obtain Figure 3 The soft-pack battery cell 100 shown is a soft-pack lithium-ion battery cell.

[0070] In this embodiment, the liquid injection hole 103B is formed to enable the soft-pack battery cell 100 to achieve secondary liquid injection as easily as the hard-shell battery cell.

[0071] The present application is not limited to this. Those skilled in the art should be aware that various changes and modifications can be made within the scope disclosed in the present application. For example, in the case where the opening 101O of the air bag 101 is set on the side of the bare battery cell 104, the liquid injection of the soft-pack battery cell 100 can also be achieved by the method disclosed in the present application.

[0072] In summary, the liquid injection method for soft-pack batteries provided in the present application can simplify the secondary liquid injection process of soft-pack batteries, and can be modified on the original primary liquid injection production line or equipment, with high feasibility; in addition, the soft-pack batteries can be easily injected with liquid twice like hard-shell batteries.

[0073] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for injecting liquid into a soft-pack battery cell, characterized in that: include: A first injection, a formation after the first injection, and a second injection after the formation, wherein: Before the formation and before or after the primary liquid injection, the opening of the air bag of the soft-pack battery cell is sealed, and the air bag is provided with a liquid replenishing device through the sealing, wherein the air bag is used to contain the gas generated by the formation, and After the formation, the electrolyte is provided to the air bag through the liquid replenishing device so that the electrolyte enters the bare cell of the soft-pack cell, thereby realizing secondary liquid injection.

2. The method for injecting liquid into a soft-pack battery cell according to claim 1, characterized in that: The liquid replenishing device is a closed cavity disposed in the air bag and containing the electrolyte. After the formation, the sealed cavity allows the electrolyte to flow out of the sealed cavity and enter the bare battery cell through the air bag.

3. The method for injecting liquid into a soft-pack battery cell according to claim 1, characterized in that: The liquid replenishing device is a liquid injection hole arranged at the position of the seal. Wherein, after the formation, electrolyte is injected into the air bag through the injection hole, and the electrolyte flows through the air bag and enters the bare battery cell.

4. The method for injecting liquid into a soft-pack battery cell according to claim 2, characterized in that: After the primary injection and before the formation, a weak portion is provided between the opening of the air bag and the bare battery cell to form an independent chamber in the air bag. The electrolyte is filled into the independent chamber from the opening, and then the opening is sealed to place the electrolyte in the independent chamber, thereby forming the closed cavity containing the electrolyte disposed in the air bag, The closed cavity is squeezed to break the weak portion, so that the electrolyte flows out from the weak portion and then passes through the air bag and is injected into the bare battery cell.

5. The method for injecting liquid into a soft-pack battery cell according to claim 2, characterized in that: During the secondary liquid injection process, the sealing ensures that the air bag is always in an airtight sealed state.

6. The method for injecting liquid into a soft-pack battery cell according to claim 3, characterized in that: Before the first injection, the opening of the air bag is sealed, and the injection hole is arranged at the sealing position. Wherein, the communication between the air bag and the outside of the soft-pack battery core is achieved through the injection hole.

7. The method for injecting liquid into a soft-pack battery cell according to claim 6, characterized in that: During the secondary liquid injection process, the liquid injection hole is fixed by the seal.

8. The method for injecting liquid into a soft-pack battery cell according to claim 6, characterized in that: After the sealing and before the formation, the bare cell of the soft-pack cell is injected with liquid once through the injection hole.

9. The method for injecting liquid into a soft-pack battery cell according to claim 1, characterized in that: After the secondary liquid injection, the outer shell of the soft-pack battery cell is heat-sealed to separate the air bag from the bare battery cell, and then the air bag is cut off.

10. The method for injecting liquid into a soft-pack battery cell according to any one of claims 1 to 9, characterized in that: The soft-pack battery cell is a soft-pack lithium-ion battery cell.

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