Battery pole group manufacturing method and battery

Abstract

The invention relates to a manufacturing method of a pole group of a battery and the battery, and relates to the technical field of chemical batteries, the manufacturing method of the pole group of the battery comprises the following steps: sequentially stacking a positive plate, a diaphragm plate and a negative plate, and carrying out thermal compounding treatment to obtain a single-layer battery pole group; carrying out primary insulation detection on the single-layer battery pole group, and preparing the qualified single-layer battery pole group and the diaphragm pole roll into a battery core package by adopting a lamination process; and carrying out secondary insulation detection on the battery core bag, putting the qualified battery core bag into a shell, injecting liquid, and carrying out formation to prepare the battery. According to the invention, the single-layer pole group is prepared, the primary insulation detection is carried out, the multi-pole group modules are stacked to form the battery, and the secondary insulation detection is carried out, so that the detection rate of the short circuit of the battery is improved, the short circuit risk of the battery is reduced, the safety performance of the lithium battery is improved, and the defects in the prior art are overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical batteries, and in particular to a method for manufacturing a battery pole group and a battery. Background Art

[0002] Secondary batteries, especially lithium batteries, have been widely used in various electronic products and new energy vehicles due to their excellent energy density, long cycle life and outstanding environmental performance. As the core power source of new energy vehicles, the safety performance of lithium batteries has always been the focus of the battery industry.

[0003] The manufacturing process of batteries is mainly divided into two types: winding and lamination, which depends on the assembly method of the positive and negative electrodes of the battery. At present, the commonly used lamination process is to use Z-shaped lamination technology to isolate the negative and positive electrodes on both sides of the diaphragm and stack them to form a battery core pack. Subsequently, they are shaped by tape bundling, and insulation resistance tests are performed before they are finally assembled into the shell.

[0004] However, during the preparation of the pole piece, due to the influence of processing and workshop environmental cleanliness, some foreign particles may be deposited on the surface of the pole piece and the diaphragm. These deposited foreign particles may pierce the diaphragm after battery assembly, causing a short circuit between the positive and negative electrodes, thereby affecting the safety performance of the battery cell. The current method of detecting insulation resistance after stacking is not ideal due to the large number of stacked layers, so it is urgently needed to be improved. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for manufacturing a battery electrode group and a battery.

[0006] In a first aspect, the present invention provides a method for manufacturing a battery electrode group, the method comprising the following steps:

[0007] The positive electrode sheet, the separator sheet, and the negative electrode sheet are stacked in sequence, and a single-layer battery electrode group is obtained after thermal composite treatment;

[0008] The single-layer battery electrode group is subjected to an insulation test, and the single-layer battery electrode group and the diaphragm electrode roll that pass the test are made into a battery core pack by a lamination process;

[0009] The battery core pack is subjected to secondary insulation testing, and the battery core pack that passes the test is placed in a shell, injected with liquid, and formed to form a battery.

[0010] Furthermore, the preparation of the positive electrode sheet includes the following process: the positive electrode roll is processed through rolling, slitting and die-cutting processes to prepare a single-sheet positive electrode sheet; wherein the size of the positive electrode sheet coated with active material is L1*W1, wherein L1 is the length of the positive electrode sheet, and W1 is the width of the positive electrode sheet;

[0011] The preparation of the negative electrode sheet includes the following process: the negative electrode roll is processed through rolling, slitting and die-cutting processes to prepare a single-sheet negative electrode sheet; wherein the size of the area of ​​the negative electrode sheet coated with active material is L2*W2, wherein L2 is the length of the negative electrode sheet, and W2 is the width of the negative electrode sheet.

[0012] Furthermore, L2-L1≥3mm, W2-W1≥2mm.

[0013] Furthermore, the preparation of the negative electrode sheet includes the following process: cutting the separator pole roll 1 into a single-piece separator sheet; wherein the size of the separator sheet is L3*W3, wherein L3 is the separator length, and W3 is the separator width.

[0014] Furthermore, L3-L2≥3mm, W3-W1≥1.5mm.

[0015] Furthermore, both sides of the diaphragm are coated with a coating layer, the coating layer is composed of one or more of polyvinylidene fluoride, acrylate copolymer, polyimide, polyacrylonitrile, methacrylonitrile, and polymethyl methacrylate, and the thickness of the coating layer is 0.5 μm-3 μm.

[0016] Furthermore, the stacking working condition parameters include: the diaphragm sheet exceeds the negative electrode sheet by a dimension of (L3-L2) / 2 on one side in the length direction, and the diaphragm sheet exceeds the negative electrode sheet by a dimension of (W3-W2) / 2 on one side in the width direction.

[0017] Furthermore, the working condition parameters of the thermal composite include: pressure of 0.1-2MPa, temperature of 45-90°C, and time of 1-30s; during the primary insulation resistance test, a pressure of 0.1-2MPa is applied, and the area of ​​the pressure completely covers the diaphragm; during the secondary insulation resistance test, a pressure of 0.1-5MPa is applied, and the area of ​​the pressure completely covers the diaphragm.

[0018] Furthermore, when preparing the battery core pack, a layer of negative electrode sheet is added after the outermost electrode group and diaphragm stack; the diaphragm electrode roll is one of a ceramic diaphragm, a single-sided glue-coated diaphragm, and a double-sided glue-coated diaphragm.

[0019] In a second aspect, the present invention provides a battery, wherein the battery is manufactured using the electrode group manufacturing method described in any one of the first aspects.

[0020] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0021] The embodiment of the present invention provides a method for manufacturing a battery electrode group and a battery. The present invention prepares a single-layer electrode group, performs a primary insulation test, and then stacks a multi-electrode group module into a battery and performs a secondary insulation test, thereby improving the detection rate of battery short circuits, reducing the risk of battery short circuits, and improving the safety performance of lithium batteries, thereby making up for the shortcomings of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A schematic flow chart of a method for manufacturing a battery electrode group provided in an embodiment of the present invention.

[0025] Figure 2 It is a schematic diagram of the structure of a single-layer battery electrode group of the present invention.

[0026] Figure 3 The structure of the battery of the present invention is shown in FIG. Figure 1 .

[0027] Figure 4 The structure of the battery of the present invention is shown in FIG. Figure 2 .

[0028] Figure 2 and Figure 3 In the middle: 1 is the battery electrode group, 101 is the positive electrode sheet, 102 is the negative electrode sheet, 103 is the diaphragm sheet, and 2 is the diaphragm. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0031] In a first aspect, the present invention provides a method for manufacturing a battery electrode group, such as Figure 1 As shown, the battery electrode group manufacturing method comprises the following steps:

[0032] The positive electrode sheet, the separator sheet, and the negative electrode sheet are stacked in sequence, and a single-layer battery electrode group is obtained after thermal composite treatment;

[0033] The single-layer battery electrode group is subjected to an insulation test, and the single-layer battery electrode group and the diaphragm electrode roll that pass the test are made into a battery core pack by a lamination process;

[0034] The battery core pack is subjected to secondary insulation testing, and the battery core pack that passes the test is placed in a shell, injected with liquid, and formed to form a battery.

[0035] The present invention prepares a single-layer electrode group, performs an insulation test, and then performs a secondary insulation test after stacking multiple electrode group modules into a battery, thereby improving the detection rate of battery short circuits, reducing the risk of battery short circuits, and improving the safety performance of lithium batteries, thereby making up for the shortcomings of the existing technology.

[0036] In some specific embodiments, the method for manufacturing a battery electrode group provided by the present invention specifically includes the following process:

[0037] S1: Preparation of positive electrode sheet: The positive electrode roll is processed through rolling, slitting and die-cutting processes to prepare a single-sheet positive electrode sheet.

[0038] S2: Negative electrode sheet preparation: The negative electrode roll is processed through rolling, slitting and die-cutting processes to prepare a single negative electrode sheet.

[0039] S3: Preparation of diaphragm sheets: cutting the diaphragm pole roll 1 into single-piece diaphragm sheets;

[0040] S4: Preparation of battery electrode group: stack the positive electrode sheet, the diaphragm sheet, and the negative electrode sheet in sequence, and obtain the battery electrode group after thermal composite treatment

[0041] S5: Primary insulation test: Test the insulation resistance between the positive and negative electrodes of the electrode groups stacked in step S4, and transfer the qualified electrode groups to the next

[0042] S6: Core pack preparation: The electrode group and the separator electrode roll 2 prepared in step S5 are laminated to form a battery core pack.

[0043] S7: Secondary insulation test: The battery pack prepared in step S6 is tested for insulation resistance between the positive and negative electrodes.

[0044] Qualified pole group transfer

[0045] S8: Battery preparation: After the qualified battery cores tested in step S7 are packed into shells, injected with liquid, and formed, batteries are manufactured.

[0046] In the step S1, the size of the area where the electrode is coated with the active material is L1*W1.

[0047] Furthermore, L1 is the length of the pole piece, and W1 is the width of the pole piece.

[0048] In step S2, the size of the area where the electrode is coated with the active material is L2*W2.

[0049] Furthermore, L2 is the length of the pole piece, and W2 is the width of the pole piece.

[0050] Furthermore, L2-L1≥3mm, W2-W1≥2mm. The purpose of controlling the above parameter relationship in the present invention is to improve the safety performance of the battery cell. Avoid lithium deposition at the edge of the negative electrode plate due to edge effect during charging. After multiple charge and discharge, lithium deposition and lithium dendrite formation will cause the diaphragm to be punctured, resulting in a short circuit between the positive and negative electrodes, and in severe cases, thermal runaway (common design solution in the industry); if L2-L1<3mm, W2-W1<2mm, the adverse effect is that when lithium ions are embedded in the negative electrode during charging, lithium deposition may occur in the area beyond the edge of the electrode plate, which may cause a short circuit between the positive and negative electrodes and thermal runaway in severe cases.

[0051] In step S3, the size of the diaphragm is L3*W3.

[0052] Furthermore, L3 is the length of the diaphragm, and W3 is the width of the diaphragm.

[0053] Furthermore, L3-L2≥3mm, W3-W1≥1.5mm. The purpose of controlling the above parameter relationship in the present invention is to ensure that the diaphragm covers the negative electrode sheet to avoid direct contact between the positive and negative electrodes, resulting in short circuit and thermal runaway; if L3-L2<3mm, W3-W1<2mm, the adverse effect is that the negative electrode sheet may come into direct contact with the positive electrode sheet, resulting in short circuit, which may cause thermal runaway of the battery in severe cases and affect the safety performance of the battery cell.

[0054] Furthermore, both sides of the diaphragm are coated with a rubber layer.

[0055] In step S4, during the stacking process, the negative electrode sheet exceeds the positive electrode sheet by (L2-L1) / 2 on one side in the length direction, and the negative electrode sheet exceeds the positive electrode sheet by (W2-W1) / 2 on one side in the width direction. The purpose of controlling the above parameter relationship in the present invention is to avoid that the coating amount of the electrode sheet on one side is too small, and lithium deposition occurs at the edge of the electrode sheet when the negative electrode is embedded with lithium, causing thermal runaway.

[0056] Preferably, in step S4, during the stacking process, the diaphragm exceeds the negative electrode sheet by (L3-L2) / 2 on one side in the length direction, and the diaphragm exceeds the negative electrode sheet by (W3-W2) / 2 on one side in the width direction. The function of controlling the above parameter relationship in the present invention is to prevent the negative electrode sheet from contacting the positive electrode sheet due to insufficient coating on one side, causing a short circuit, triggering thermal runaway, and affecting the safety performance of the battery.

[0057] Preferably, in step S4, the thermal compounding pressure is 0.1-2 MPa, the temperature is 45-90° C., and the time is 1-30 s.

[0058] Preferably, in step S4, the thermally compounded area completely covers the diaphragm area.

[0059] In step S5, a certain pressure is applied during the insulation resistance test.

[0060] Furthermore, the pressure area completely covers the diaphragm, and the pressure is 0.1-2 MPa.

[0061] In the step S6, after the outermost electrode group and the diaphragm are stacked, a layer of negative electrode is added to increase the capacity of the battery cell.

[0062] Preferably, in step S6, the diaphragm pole roll 2 is one of a ceramic diaphragm, a single-sided glue-coated diaphragm, and a double-sided glue-coated diaphragm.

[0063] Preferably, in step S7, a certain pressure is applied during the insulation resistance test.

[0064] Furthermore, the pressure area completely covers the core package, and the pressure is 0.1-5 MPa.

[0065] In a second aspect, the present invention provides a battery, wherein the battery is manufactured using the electrode group manufacturing method described in any one of the first aspects.

[0066] It should be noted that the electrode group manufacturing method of the battery provided in the embodiment of the present invention and the component raw materials involved in the battery, unless otherwise specified or specified, can directly adopt commercially available products or adopt existing public preparation methods to make them themselves; at the same time, the steps and parameters involved, unless otherwise specified or specified, can be carried out according to the existing electrode group manufacturing method of the battery or directly carried out using existing equipment, and the present invention document will not elaborate on them one by one.

[0067] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0068] Example 1

[0069] This example provides a pole group manufacturing process and a battery, such as Figure 2-Figure 3 As shown, the following steps are included:

[0070] S1: The coated and dried positive electrode roll is processed through rolling, slitting and die-cutting to prepare a single-piece positive electrode sheet with a size of 100mm*30mm;

[0071] S2: The negative electrode coil after coating and drying is processed by rolling, slitting and die-cutting to prepare a single negative electrode sheet with a size of 104mm*33mm;

[0072] S3: Cut the double-sided glue-coated diaphragm pole roll 1 into single-piece diaphragm sheets, the size of the diaphragm sheets is 108mm*35mm;

[0073] S4: The positive electrode sheet prepared in step S1, the diaphragm sheet prepared in step S3, and the negative electrode sheet prepared in step S2 are stacked in sequence, and a pressing plate with an area of ​​40 mm*110 mm is applied, and the pressing plate area completely covers the diaphragm, and the pressure is continuously applied for 10 seconds under the conditions of a temperature of 60°C and a pressure of 0.5 MPa to prepare a single-layer electrode group;

[0074] S5: externally connect the positive and negative electrodes of the electrode group prepared in step S4 to voltage, detect the insulation resistance between the positive and negative electrodes, and turn on the qualified electrode group;

[0075] S6: The plurality of electrode groups prepared in step S5 and the double-sided adhesive-coated separator electrode roll 2 are laminated to form a battery core pack. Figure 3 ;

[0076] S7: the core package prepared in step S6 is tested for insulation resistance between the positive and negative electrodes, and the qualified core packages are transferred to the next stage;

[0077] S8: The qualified battery core is packed into a shell, injected with liquid, and formed into a battery.

[0078] Example 2

[0079] This example provides an electrode group manufacturing process and a battery, which differs from Example 1 only in that: Example 2 differs from Example 1 in that: in step S6, an additional layer of negative electrode sheet and separator electrode roll 2 are stacked, such as Figure 4 shown.

[0080] Comparative Example 1

[0081] This example provides a pole group manufacturing process and a battery, including the following steps:

[0082] S1: The coated and dried positive electrode roll is processed through rolling, slitting and die-cutting to prepare a single-piece positive electrode sheet with a size of 100mm*30mm;

[0083] S2: The negative electrode coil after coating and drying is processed by rolling, slitting and die-cutting to prepare a single negative electrode sheet with a size of 104mm*33mm;

[0084] S3: The negative electrode sheet, the separator electrode roll 1, and the positive electrode sheet are stacked to form a battery core pack by a stacking process, wherein the positive electrode sheet is stacked in 15 layers and the negative electrode sheet is stacked in 16 layers;

[0085] S4: testing the insulation resistance between the positive and negative electrodes of the core package prepared in step S3, and transferring the qualified core package to the next stage;

[0086] S5: The qualified battery core is packed into a shell, injected with liquid, and formed into a battery.

[0087] Test Case

[0088] In this example, the pass rates of the core insulation resistance tests of the above-mentioned embodiments and comparative examples are shown in Table 1 below.

[0089] Table 1

[0090] project Example 1 Example 2 Comparative Example 1 Number of tests 200 200 200 Qualified quantity 199 198 193 Pass rate 99.5％ 99％ 96.5％

[0091] In addition, in this example, the self-discharge of the above-mentioned embodiment and comparative example batteries was tested, and the test pass rates are shown in Table 2 below.

[0092] Table 2

[0093] project Example 1 Example 2 Comparative Example 1 Number of tests 199 198 193 Qualified quantity 199 197 189 Pass rate 100.00％ 99.49％ 97.93％

[0094] It can be seen from the data in Table 1 and Table 2 that the insulation resistance test pass rate and battery self-discharge pass rate of the embodiment of the present invention are significantly better than those of the comparative example.

[0095] In summary, the present invention proposes an electrode group manufacturing process and a battery, in which a positive electrode sheet, a diaphragm and a negative electrode sheet are prepared into an electrode group, the manufacturing process is modularized, and the core package is formed by stacking electrode groups, which reduces the difficulty of the manufacturing process; after the electrode group is manufactured, an insulation test is performed by applying pressure, and the phenomenon of foreign matter on the surface of the positive electrode sheet, the negative electrode sheet or the diaphragm piercing the diaphragm can be detected in advance, and the short circuit between the positive electrode sheet and the negative electrode sheet can be identified in advance, which reduces the difficulty of detecting foreign matter on the surface of the electrode sheet or the diaphragm caused by the large thickness of the battery core package; on the other hand, when designing the battery, in order to ensure the safety performance of the battery, the negative electrode sheet is generally coated with the positive electrode sheet. The electrode group prepared by the present invention can intuitively detect the situation that the negative electrode sheet coats the positive electrode sheet, which is convenient for timely adjusting the equipment accuracy, and realizing the improvement of the safety performance of the battery. At the same time, it can improve the qualified rate of the battery and reduce the manufacturing cost.

[0096] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0097] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for manufacturing a battery electrode group, characterized in that: The battery electrode group manufacturing method comprises the following steps: The positive electrode sheet, the separator sheet, and the negative electrode sheet are stacked in sequence, and a single-layer battery electrode group is obtained after thermal composite treatment; The single-layer battery electrode group is subjected to an insulation test, and the single-layer battery electrode group and the diaphragm electrode roll that pass the test are made into a battery core pack by a lamination process; The battery core pack is subjected to secondary insulation testing, and the battery core pack that passes the test is placed in a shell, injected with liquid, and formed to form a battery.

2. The method for manufacturing a battery electrode group according to claim 1, characterized in that: The preparation of the positive electrode sheet includes the following process: the positive electrode roll is processed through rolling, slitting and die cutting to prepare a single-sheet positive electrode sheet; wherein the size of the positive electrode sheet coated with active material is L1*W1, wherein L1 is the length of the positive electrode sheet, and W1 is the width of the positive electrode sheet; The preparation of the negative electrode sheet includes the following process: the negative electrode roll is processed through rolling, slitting and die-cutting processes to prepare a single-sheet negative electrode sheet; wherein the size of the area of ​​the negative electrode sheet coated with active material is L2*W2, wherein L2 is the length of the negative electrode sheet, and W2 is the width of the negative electrode sheet.

3. The method for manufacturing a battery electrode group according to claim 2, characterized in that: L2-L1≥3mm, W2-W1≥2mm.

4. The method for manufacturing a battery electrode group according to claim 3, characterized in that: The preparation of the negative electrode sheet includes the following process: cutting the separator pole roll 1 into a single-piece separator sheet; wherein the size of the separator sheet is L3*W3, wherein L3 is the separator length, and W3 is the separator width.

5. The method for manufacturing a battery electrode group according to claim 4, characterized in that: L3-L2≥3mm, W3-W1≥1.5mm.

6. The method for manufacturing a battery electrode group according to claim 5, characterized in that: Both sides of the diaphragm are coated with a coating layer, the coating layer is composed of one or more of polyvinylidene fluoride, acrylate copolymer, polyimide, polyacrylonitrile, methacrylonitrile, polymethyl methacrylate, and the thickness of the coating layer is 0.5 μm-3 μm.

7. The method for manufacturing a battery electrode group according to claim 6, characterized in that: The stacking working condition parameters include: the diaphragm sheet exceeds the negative electrode sheet by (L3-L2) / 2 on one side in the length direction, and the diaphragm sheet exceeds the negative electrode sheet by (W3-W2) / 2 on one side in the width direction.

8. The method for manufacturing a battery electrode group according to claim 1, characterized in that: The working condition parameters of the thermal composite include: pressure of 0.1-2MPa, temperature of 45-90°C, and time of 1-30s; during the primary insulation resistance test, a pressure of 0.1-2MPa is applied, and the area of ​​the pressure completely covers the diaphragm; during the secondary insulation resistance test, a pressure of 0.1-5MPa is applied, and the area of ​​the pressure completely covers the diaphragm.

9. The method for manufacturing a battery electrode group according to claim 1, characterized in that: When preparing the battery core pack, a negative electrode sheet is added after the outermost electrode group and diaphragm stack; the diaphragm electrode roll is one of a ceramic diaphragm, a single-sided glue-coated diaphragm, and a double-sided glue-coated diaphragm.

10. A battery, characterized in that: The battery is manufactured by the electrode group manufacturing method according to any one of claims 1 to 9.

Images