A method for processing a battery core

Abstract

This application relates to a method for processing a battery cell, comprising: preparing positive and negative electrode sheets; stacking and rolling the positive electrode sheet, separator, and negative electrode sheet to form an electrode assembly; winding the electrode assembly to form a racetrack-shaped winding structure; hot-pressing the winding structure; placing the hot-pressed winding structure into a housing; injecting electrolyte into the housing through an injection port; sealing the injection port to form a first battery cell; statistically analyzing the fold parameters of the arc-shaped folds in the arc region of the first battery cell; when the fold parameters of the arc-shaped folds are greater than a first preset value, reducing the winding tension of the winding electrode assembly, and / or reducing the hot-pressing pressure of the hot-pressed winding structure, so as to reduce the length and number of arc-shaped folds, reduce the thickness difference between the straight wall region and the arc region of the winding structure, and improve the processing yield of the battery cell in subsequent processing.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a method for processing a battery cell. Background Art

[0002] The battery cell includes a shell and a winding structure disposed in the shell. During the processing, the positive electrode sheet, the isolation film and the negative electrode sheet need to be stacked and rolled to form a sheet assembly, and then the sheet assembly is wound to form a runway-shaped winding structure, and then the winding structure is hot pressed. During the winding and hot pressing process, due to the inconsistency in the expansion and deformation degree of the positive electrode sheet and the negative electrode sheet, the inner layer of the winding structure will have more or thicker arc wrinkles. The stacking of multiple layers of arc wrinkles will cause a large difference in thickness between the straight wall area and the arc area of ​​the battery cell, and a large degree of wrinkles, which will reduce the processing yield of the battery cell. Summary of the invention

[0003] The present application provides a method for processing an electric core, which can reduce the number and size of arc wrinkles in subsequent processing and the degree of wrinkles of the electric core.

[0004] The present application provides a method for processing a battery cell, comprising:

[0005] Preparing positive electrode sheets and negative electrode sheets;

[0006] The positive electrode sheet, the separator and the negative electrode sheet are stacked and rolled to form a electrode sheet assembly;

[0007] Winding the pole piece assembly to form a winding structure, wherein the winding structure includes straight wall areas relatively arranged along the thickness direction thereof, adjacent straight walls are connected by arc areas, and the straight wall areas and the arc areas form a racetrack-shaped structure;

[0008] hot pressing the wound structure;

[0009] placing the hot-pressed coiled structure into a housing;

[0010] injecting electrolyte into the housing through the injection port;

[0011] The liquid injection port is sealed to form a first battery cell;

[0012] Count the wrinkle parameters of the arc wrinkles in the arc area of ​​the first battery cell. When the wrinkle parameters of the arc wrinkles are greater than a first preset value, reduce the winding tension of the wound pole piece assembly, and process the second battery cell with the adjusted winding tension, and / or reduce the hot pressing pressure of the hot pressing winding structure, and process the second battery cell with the adjusted hot pressing pressure.

[0013] In the present application, when the wrinkle parameter of the arc-shaped wrinkles of the battery cell is greater than a first preset value, the winding tension and / or hot pressing pressure of the battery cell can be reduced to reduce the length of the arc-shaped wrinkles, reduce the number of arc-shaped wrinkles and the wrinkle degree of the arc-shaped wrinkles, thereby reducing the thickness difference between the straight wall area and the arc-shaped area of ​​the winding structure, thereby improving the processing yield of the battery cell in subsequent processing.

[0014] In a possible design, the step of counting wrinkle parameters of the arc wrinkles of the first battery cell in the arc area includes:

[0015] Disassemble the first battery cell and take out the winding structure inside the first battery cell;

[0016] Unfolding the winding structure of the first battery cell;

[0017] Statistics of fold parameters of arc folds.

[0018] In a possible design, the step of calculating the fold parameters of the arc folds includes:

[0019] Perform CT scanning on the unfolded winding structure and transmit the scanning effect image to the central control system;

[0020] The central control system identifies the wrinkle area in the scanning effect image and counts the wrinkle parameters of the wrinkle area.

[0021] In a possible design, the step of counting wrinkle parameters of the arc wrinkles of the first battery cell in the arc area includes:

[0022] Disassemble the first battery cell and take out the winding structure inside the first battery cell;

[0023] Perform CT scanning on the end surface of the winding structure and transmit the scanning effect image to the central control system;

[0024] The central control system identifies the number of fold distribution layers and the fold parameters of the arc folds in the scanning effect diagram.

[0025] In a possible design, the number N1 of arcuate wrinkles satisfies: when N1 ≥ 6, the arcuate wrinkles are judged to be small wrinkles, and the hot pressing pressure of the hot pressing winding structure is reduced; when the number N1 of arcuate wrinkles satisfies: when 2 < N1 < 6, the arcuate wrinkles are judged to be large wrinkles, and the winding tension of the wound pole piece assembly is reduced.

[0026] In a possible design, the pole piece assembly includes a lithium-intercalation region and a non-lithium-intercalation region, and in the winding structure, step wrinkles exist at the junction of the lithium-intercalation region and the non-lithium-intercalation region;

[0027] Before or after counting wrinkle parameters of arc wrinkles of the first battery cell at the arc region, the battery cell processing method includes:

[0028] The wrinkle parameters of the step wrinkles are counted, and when the wrinkle parameters of the step wrinkles are greater than a second preset value, the hot pressing pressure of the hot pressing winding structure is reduced, and the second battery cell is processed with the adjusted hot pressing pressure.

[0029] In a possible design, the step of calculating the fold parameters of the step folds includes:

[0030] Disassemble the first battery cell and take out the winding structure inside the first battery cell;

[0031] Unfolding the winding structure of the first battery cell;

[0032] Statistics of fold parameters of step folds.

[0033] In a possible design, the step of calculating the fold parameters of the step folds includes:

[0034] Disassemble the first battery cell and take out the winding structure inside the first battery cell;

[0035] Perform CT scanning on the end surface of the winding structure and transmit the scanning effect image to the central control system;

[0036] The central control system recognizes the wrinkle parameters of the step wrinkles in the scanning effect image.

[0037] In one possible design, after the step of forming the first battery cell, the battery cell processing method includes:

[0038] Detect the thickness of the first battery cell in the straight wall area and record it as H1, and detect the maximum thickness of the first battery cell in the arc area and record it as H2;

[0039] Calculate the wrinkle degree S of the first battery cell, S=(H2-H1) / H1;

[0040] When S≤0.05, the first battery cell is determined to be a qualified battery cell, and batch processing is performed with the winding tension and hot pressing pressure of the first battery cell;

[0041] When S>0.05, the first battery cell is determined to be an unqualified battery cell, and wrinkle parameters of arc wrinkles in the arc area of ​​the first battery cell are counted, and / or wrinkle parameters of step wrinkles of the first battery cell are counted.

[0042] In a possible design, the winding tension F of the wound pole piece assembly satisfies: 300g≤F≤800g; and the hot pressing pressure P of the hot pressing winding structure is reduced to satisfy: 5t≤P≤12t.

[0043] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 An exploded view of a battery cell in one embodiment;

[0045] Figure 2 A schematic diagram of the stacked structure of a positive electrode sheet, a separator and a negative electrode sheet;

[0046] Figure 3 It is a schematic diagram of the local structure of the winding structure of the battery cell;

[0047] Figure 4 is a cross-sectional view of the arc-shaped folds on the winding structure;

[0048] Figure 5 is a schematic diagram of arc-shaped wrinkles on the pole piece assembly after unfolding;

[0049] Figure 6 A schematic diagram of the step folds on the unfolded pole piece assembly;

[0050] Figure 7 A process flow chart of a battery cell in one embodiment;

[0051] Figure 8 A processing flow chart of a battery cell in another embodiment;

[0052] Fig. 9 is a processing flow chart of a battery cell in yet another embodiment;

[0053] Fig.10 The present invention is a processing flow chart of a battery cell in yet another embodiment.

[0054] Reference numerals:

[0055] 1- Shell;

[0056] 11- housing;

[0057] 12-upper cover;

[0058] 2- winding structure;

[0059] 21- positive electrode;

[0060] 22- isolation film;

[0061] 23- negative electrode;

[0062] 24-pole piece assembly;

[0063] 25-ear;

[0064] 26-lithium insertion area;

[0065] 27-non-lithium insertion area;

[0066] 28-straight wall area;

[0067] 29-arc zone;

[0068] 3-arc-shaped folds;

[0069] 4- Step folds.

[0070] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application. DETAILED DESCRIPTION

[0071] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0072] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0073] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0074] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0075] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present application are described at the angles shown in the accompanying drawings and should not be understood as limiting the embodiments of the present application. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0076] The battery cell is the part of the battery that undergoes electrochemical reactions to generate electrical energy. Figure 1 As shown, the battery cell includes a housing 1 and a winding structure 2 disposed in the housing 1. The housing 1 includes a shell 11 and an upper cover 12. The shell 11 and the upper cover 12 form a cavity for accommodating the winding structure 2. Figure 1 As shown, the winding structure 2 is provided with a pole lug 25, and the pole lug 25 is used to connect with the positive pole and the negative pole of the battery to achieve the output of electric energy.

[0077] like Figure 2 As shown, the winding structure 2 includes a positive electrode sheet 21, a negative electrode sheet 23 and a separator 22, wherein the separator 22 is located between the positive electrode sheet 21 and the negative electrode sheet 23 and is used to separate the positive electrode sheet 21 and the negative electrode sheet 23. The negative electrode sheet 23 includes a negative electrode current collector and a negative electrode active material layer coated on the surface of the negative electrode current collector, and the negative electrode active material layer constitutes a lithium insertion area 26 of the negative electrode sheet 23. The positive electrode sheet 21 includes a positive electrode current collector and a positive electrode active material layer coated on the surface of the positive electrode current collector, and the positive electrode active material layer constitutes a lithium insertion area 26 of the positive electrode sheet 21. The negative electrode active material layer, the positive electrode active layer and the separator 22 located therebetween are wound to form the winding structure 2.

[0078] The negative electrode current collector can be cut to form the negative electrode tab, and the positive electrode current collector can be cut to form the positive electrode tab. The positive electrode tab and the negative electrode tab can be located together at one end of the winding structure 2, or the positive electrode tab and the negative electrode tab can be located at both ends of the winding structure 2 respectively.

[0079] The positive electrode tab is electrically connected to the positive electrode post through the positive electrode connector, and the negative electrode tab is electrically connected to the negative electrode post through the negative electrode connector. During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material in the winding structure 2 react with the electrolyte to generate electrical energy, which is then conducted to the positive electrode post through the positive electrode tab and the positive electrode connector, and to the negative electrode post through the negative electrode tab and the negative electrode connector, and the electrical energy is output through the positive electrode post and the negative electrode post.

[0080] The processing of the battery cell is as follows:

[0081] Prepare a positive electrode sheet 21 and a negative electrode sheet 23;

[0082] The positive electrode sheet 21, the separator 22 and the negative electrode sheet 23 are stacked into a sheet assembly 24 by a stacking machine;

[0083] Winding the pole piece assembly 24 to form a winding structure 2;

[0084] The winding structure 2 is hot pressed to make the positive electrode sheet 21, the negative electrode sheet 23 and the separator 22 more tightly bonded to reduce the risk of looseness inside the battery cell;

[0085] Put the hot-pressed coiled structure 2 into the housing 1;

[0086] Injecting electrolyte into the housing 1 through the injection port;

[0087] The liquid injection port is sealed to form a battery cell.

[0088] The steps of preparing the positive electrode sheet 21 and the negative electrode sheet 23 include:

[0089] Prepare positive electrode active material and negative electrode active material; specifically, mix active material, inactive material, binder, solvent and other raw materials in a specific ratio to prepare positive electrode active material and negative electrode active material that meet the viscosity and solid content requirements. The embodiment of the present application does not specifically limit the type, quantity and mixing ratio of the raw materials;

[0090] The positive electrode active material is coated on the front side of the positive electrode current collector; the negative electrode active material is coated on the front side of the negative electrode current collector;

[0091] The coated positive electrode current collector roll is subjected to high pressure rolling and extrusion to compact it to the designed thickness to ensure that the positive electrode active material and the positive electrode current collector are closely combined; the coated negative electrode current collector roll is subjected to high pressure rolling and extrusion to compact it to the designed thickness to ensure that the negative electrode active material and the negative electrode current collector are closely combined;

[0092] The coiled material is punched into the size actually required by the battery to form the positive electrode sheet 21 and the negative electrode sheet 23 .

[0093] like Figure 3 As shown, the winding structure 2 includes straight wall areas 28 arranged relatively along its thickness direction, and adjacent straight walls are connected by arc areas 29, and the straight wall areas 28 and the arc areas 29 form a racetrack-shaped structure. In the process of winding the pole piece assembly 24 to form the racetrack-shaped winding structure 2, and in the process of hot pressing the winding structure 2, due to the inconsistent expansion and deformation degree of the positive pole piece 21 and the negative pole piece 23, the inner layer of the winding structure 2 will have more or thicker arc wrinkles 3, refer to Figure 4 and Figure 5 The stacking of multiple layers of arc-shaped wrinkles 3 will result in a large difference in thickness between the straight wall area 28 and the arc-shaped area 29 of the battery cell, and a large degree of wrinkles on the entire battery cell, thereby reducing the processing yield of the battery cell.

[0094] In order to reduce the wrinkle degree of the battery cell, the processing method of the battery cell provided in the embodiment of the present application further includes:

[0095] like Figure 7 As shown, the battery cell prepared according to the above steps is recorded as the first battery cell. During the processing of the first battery cell, the winding tension of the wound pole piece assembly 24 is recorded as F1, and the hot pressing pressure of the hot pressing winding structure 2 is recorded as P1;

[0096] The wrinkle parameters of the arc-shaped wrinkles 3 of the first battery cell are counted, and the wrinkle parameters of the arc-shaped wrinkles 3 include the number of arc-shaped wrinkles 3, the total length of the arc-shaped wrinkles 3 and the average length of the arc-shaped wrinkles 3. The total length of the arc-shaped wrinkles 3 is the sum of the lengths of all the arc-shaped wrinkles 3, and the average length of the arc-shaped wrinkles 3 is the ratio of the total length of the arc-shaped wrinkles 3 to the number of the arc-shaped wrinkles 3. When the wrinkle parameter of the arc-shaped wrinkle 3 is less than or equal to the first preset value, for example, when the average length of the arc-shaped wrinkle 3 is less than or equal to 0.2 mm, the wrinkle degree of the arc-shaped wrinkle 3 of the first battery cell meets the requirements, and batch processing is performed using F1 and P1; when the wrinkle parameter of the arc-shaped wrinkle 3 is greater than the first preset value, for example, when the average length of the arc-shaped wrinkle 3 is greater than 0.2 mm, the wrinkle degree of the arc-shaped wrinkle 3 of the first battery cell does not meet the requirements, the winding tension can be reduced from F1 to F2, and the second battery cell can be processed using F2, and / or the hot pressing pressure can be reduced from P1 to P2, and the second battery cell can be processed using P2.

[0097] The wrinkle parameters of the arc-shaped wrinkle 3 of the second battery cell are counted to determine whether the wrinkle degree of the arc-shaped wrinkle 3 of the second battery cell meets the requirements; when the wrinkle degree of the arc-shaped wrinkle 3 of the second battery cell meets the requirements, batch processing is performed using the winding tension and hot pressing pressure of the second battery cell; when the wrinkle degree of the arc-shaped wrinkle 3 of the second battery cell does not meet the requirements, repeat the above steps until the Nth battery cell is a qualified battery cell, and batch processing is performed using the winding tension and hot pressing pressure of the qualified battery cell.

[0098] In this embodiment, when the wrinkle parameter of the arc-shaped wrinkles 3 of the battery cell is greater than a first preset value, the winding tension and / or hot pressing pressure of the battery cell can be reduced to reduce the length of the arc-shaped wrinkles 3, reduce the number of the arc-shaped wrinkles 3 and the wrinkle degree of the arc-shaped wrinkles 3, thereby reducing the thickness difference between the straight wall area 28 and the arc-shaped area 29 of the winding structure 2, thereby improving the processing yield of the battery cell in subsequent processing.

[0099] In the process of counting the wrinkle parameters of the arc wrinkles 3 in the arc area 29 of the first battery cell, the number of arc wrinkles 3 can be directly counted from the end surface of the winding structure 2, or the winding structure 2 can be unfolded and then the wrinkle parameters of the arc wrinkles 3 can be counted. The following discusses these two possible implementations respectively.

[0100] In a possible design, the step of counting the wrinkle parameters of the arc wrinkles 3 of the first battery cell at the arc area 29 includes:

[0101] Disassemble the first battery cell and take out the winding structure 2 inside the first battery cell;

[0102] Unfolding the winding structure 2 of the first battery cell;

[0103] Count the wrinkle parameters of arc wrinkle 3.

[0104] In this embodiment, the winding structure 2 is first unfolded and then the wrinkle parameters of the arc-shaped wrinkles 3 are counted. This can increase the accuracy of the statistics on the number of arc-shaped wrinkles 3 and, at the same time, facilitate the measurement of the length dimension of the arc-shaped wrinkles 3, thereby improving the reliability of the obtained wrinkle parameters.

[0105] Specifically, the method for counting the wrinkle parameters of the arc-shaped wrinkles 3 can be machine scanning or manual counting. In the machine scanning method, the step of counting the wrinkle parameters of the arc-shaped wrinkles 3 includes:

[0106] Performing CT scanning on the unfolded winding structure 2 and transmitting the scanning effect diagram to the central control system;

[0107] The central control system identifies the wrinkle area in the scanning effect image and counts the wrinkle parameters of the wrinkle area.

[0108] In this embodiment, the fold parameters of the arcuate folds 3 are counted by CT scanning and identification by the main control system, which can improve the statistical accuracy of the fold parameters of the arcuate folds 3 and further improve the reliability of the obtained fold parameters.

[0109] In another possible design, the step of counting the wrinkle parameters of the arc wrinkles 3 of the first battery cell at the arc area 29 includes:

[0110] Disassemble the first battery cell and take out the winding structure 2 inside the first battery cell;

[0111] Perform CT scanning on the end surface of the winding structure 2 and transmit the scanning effect diagram to the central control system. Figure 4 is a schematic diagram of the contour shape of the end surface of the winding structure 2;

[0112] The central control system identifies the number of wrinkle distribution layers and wrinkle parameters of the arc wrinkle 3 in the scanning effect diagram. When the lengths of the positive electrode sheet 21, the separator 22 and the negative electrode sheet 23 are specific values, the more the number of distribution layers of the arc wrinkle 3, the smaller the wrinkle height of the arc wrinkle 3, and the smaller the number of distribution layers of the arc wrinkle 3, the larger the wrinkle height of the arc wrinkle 3. The height of the arc wrinkle 3 can be determined by the number of distribution layers of the arc wrinkle 3, so as to adaptively adjust the processing technology of the battery cell, for example, reducing the winding tension or reducing the hot pressing pressure.

[0113] In this embodiment, the end face of the winding structure 2 is directly scanned, which simplifies the steps of counting the wrinkle parameters of the arc-shaped wrinkles 3, thereby facilitating the shortening of the detection cycle of the wrinkle degree of the battery cell, and further facilitating the shortening of the cycle of adjusting the processing technology of the battery cell. In addition, directly scanning the end face of the winding structure 2 can more intuitively count the number of distribution layers of the arc-shaped wrinkles 3, thereby reducing the difficulty of counting the wrinkle parameters of the arc-shaped wrinkles 3.

[0114] After the step of counting the wrinkle parameters of the arc wrinkles 3 and before the step of adjusting the processing technology of the battery cell, it is necessary to first determine the wrinkle type of the arc wrinkles 3, that is, determine whether the arc wrinkles 3 are large wrinkles or small wrinkles, and then adjust the processing technology of the battery cell in a targeted manner according to the type of the arc wrinkles 3. Specifically, the type of the arc wrinkles 3 can be determined according to the number of distribution layers of the arc wrinkles 3 and the number of the arc wrinkles 3. The more the inner layers of the arc wrinkles 3 and the more the number of the arc wrinkles 3, the smaller the arc wrinkles 3.

[0115] Taking determining the type of the arcuate folds 3 according to the number of the arcuate folds 3 as an example, the specific steps are as follows:

[0116] When the number N1 of the arcuate wrinkles 3 satisfies: N1 ≥ 6, the arcuate wrinkles 3 are determined to be small wrinkles, and the hot pressing pressure of the hot pressing winding structure 2 is reduced.

[0117] In this embodiment, during the hot pressing of the winding structure 2, the outer pole piece assembly 24 has a larger deformation space, while the inner pole piece assembly 24 has a smaller deformation space. If the hot pressing pressure is large, there is a risk that the outer pole piece assembly 24 shrinks inwards and the shrinking space of the inner pole piece assembly 24 is limited, resulting in the appearance of arc wrinkles 3. Therefore, when the arc wrinkles 3 on the winding structure 2 are small wrinkles, the hot pressing pressure can be reduced first to reduce the deformation difference between the inner and outer pole piece assemblies 24, thereby reducing the risk of arc wrinkles 3 in the inner pole piece assembly 24, which is beneficial to reduce the number of arc wrinkles 3, so as to improve the processing yield of the battery cell.

[0118] After reducing the hot pressing pressure, if the wrinkle degree of the arc wrinkles 3 of the reprocessed battery cell still does not meet the requirements, the winding tension can be adaptively reduced.

[0119] When the number N1 of the arcuate wrinkles 3 satisfies: 2<N1<6, the arcuate wrinkles 3 are determined to be large wrinkles, and the winding tension of the wound pole piece assembly 24 is reduced.

[0120] In this embodiment, during the winding of the pole piece assembly 24, if the winding tension is large, there is a risk that the outer pole piece assembly 24 wraps around and tightens the inner pole piece assembly 24, resulting in the inner pole piece assembly 24 shrinking space being limited and arc wrinkles 3 appearing. Therefore, reducing the winding tension of the pole piece assembly 24 can reduce the risk of arc wrinkles 3 appearing in the inner pole piece assembly 24, which is beneficial to reduce the number of arc wrinkles 3, so as to improve the processing yield of the battery cell. In addition, reducing the winding tension can reduce the degree of close contact between the adjacent inner and outer pole piece assemblies 24 during the winding process. When arc wrinkles 3 appear in the inner layer, reducing the degree of close contact can reduce the risk of arc wrinkles 3 appearing in the outer layer at the same position, which is beneficial to reduce the number of arc wrinkles 3, so as to improve the processing yield of the battery cell.

[0121] After reducing the winding tension, if the degree of wrinkles of the arc wrinkles 3 of the reprocessed battery cell still does not meet the requirements, the hot pressing pressure can be adaptively reduced. When arc wrinkles 3 appear in the inner layer, the smaller hot pressing pressure further reduces the risk of arc wrinkles 3 appearing in the same position of the outer layer, which is beneficial to reduce the number of arc wrinkles 3 and improve the processing yield of the battery cell.

[0122] In addition, if Figure 5 As shown, both the positive electrode sheet 21 and the negative electrode sheet 23 have a lithium intercalation region 26 and a non-lithium intercalation region 2726, and the thickness of the lithium intercalation region 26 and the non-lithium intercalation region 2726 is different. During the hot pressing process, the expansion degree of the lithium intercalation region 26 and the non-lithium intercalation region 2726 is inconsistent, which may cause the interface between the lithium intercalation region 26 and the non-lithium intercalation region 2726 to be prone to the following phenomenon: Figure 6 As shown in the step wrinkles 4, if the hot pressing pressure is large, the inner and outer pole piece assemblies 24 will be closely fitted. When there are step wrinkles 4 on the inner layer, there will also be step wrinkles 4 on the outer side under the action of the larger hot pressing pressure, which will also cause the degree of wrinkles on the battery cell to be larger, thereby reducing the processing yield of the battery cell.

[0123] Before or after counting the wrinkle parameters of the arc-shaped wrinkles 3 of the first battery cell at the arc-shaped area 29, the battery cell processing method may further include:

[0124] like Figure 8 As shown, the wrinkle parameters of the step wrinkles 4 are counted. When the wrinkle parameters of the step wrinkles 4 are greater than a second preset value, the hot pressing pressure of the hot pressing winding structure 2 is reduced, and the second battery cell is processed with the adjusted hot pressing pressure.

[0125] Specifically, the step of counting the wrinkle parameters of the step wrinkles 4 may be performed before the step of counting the wrinkle parameters of the arc wrinkles 3, that is, the number of the step wrinkles 4 of the first battery cell is first counted, and if the number is greater than 2, the hot pressing pressure is reduced, and if the number is less than or equal to 2, the hot pressing pressure remains unchanged. Thereafter, the wrinkle parameters of the arc wrinkles 3 of the first battery cell are counted again, and if the wrinkle parameters of the arc wrinkles 3 are less than or equal to the first preset value, the winding tension and the hot pressing pressure remain unchanged, and if the wrinkle parameters of the arc wrinkles 3 are greater than the first preset value, the winding tension or the hot pressing pressure is reduced according to the number of the arc wrinkles 3.

[0126] The step of counting the fold parameters of the step folds 4 can also be performed after the step of counting the fold parameters of the arc folds 3, that is, Figure 8As shown, the wrinkle parameters of the arc wrinkles 3 of the first battery cell are first counted. If the wrinkle parameters of the arc wrinkles 3 are less than or equal to the first preset value, the winding tension and the hot pressing pressure remain unchanged. If the wrinkle parameters of the arc wrinkles 3 are greater than the first preset value, the winding tension or the hot pressing pressure is reduced according to the number of arc wrinkles 3. Thereafter, the number of step wrinkles 4 of the first battery cell is counted. If the number is greater than 2, the hot pressing pressure is reduced. If the number is less than or equal to 2, the hot pressing pressure remains unchanged.

[0127] The embodiment of the present application does not impose any special limitation on the order of counting the step folds 4 and counting the arc folds 3 .

[0128] In this embodiment, when the wrinkle parameters of the arc wrinkle 3 of the battery cell meet the requirements, under the influence of the wrinkle parameters of the step wrinkle 4, the wrinkle degree of the battery cell may still not meet the requirements. For this reason, before or after counting the wrinkle parameters of the arc wrinkle 3 of the first battery cell, it is also necessary to count the wrinkle parameters of the step wrinkle 4 of the first battery cell. If the wrinkle parameters of the step wrinkle 4 are greater than the second preset value, for example, the number of wrinkles of the step wrinkle 4 is greater than 2, it is necessary to reduce the hot pressing pressure during the hot pressing process to reduce the expansion difference between the lithium-embedded area 26 and the non-lithium-embedded area 2726, thereby reducing the risk of the occurrence of step wrinkles 4. In addition, reducing the hot pressing pressure during the hot pressing process can reduce the degree of contact between the adjacent inner and outer electrode assemblies 24 during the winding process. When a step wrinkle 4 appears in the inner layer, reducing the degree of contact can reduce the risk of the outer layer appearing a step wrinkle 4 at the same position, which is beneficial to reduce the number of step wrinkles 4, thereby improving the processing yield of the battery cell. By counting the arc wrinkles 3 and the step wrinkles 4 of the first battery cell, the accuracy of judging the wrinkle degree of the battery cell can be improved, so as to adjust the processing parameters of the battery cell in time, thereby improving the processing yield of the battery cell.

[0129] In a possible design, the step of calculating the fold parameters of the step folds 4 includes:

[0130] Disassemble the first battery cell and take out the winding structure 2 inside the first battery cell;

[0131] Unfolding the winding structure 2 of the first battery cell;

[0132] Statistics of the fold parameters of step fold 4.

[0133] In this embodiment, the winding structure 2 is first unfolded and then the wrinkle parameters of the step wrinkles 4 are counted, which can increase the accuracy of the statistics of the number of step wrinkles 4.

[0134] In another possible design, the step of calculating the fold parameters of the step folds 4 includes:

[0135] Disassemble the first battery cell and take out the winding structure 2 inside the first battery cell;

[0136] Perform CT scanning on the end surface of the winding structure 2 and transmit the scanning effect diagram to the central control system;

[0137] The central control system identifies the wrinkle parameters of the step wrinkle 4 in the scanning effect diagram.

[0138] In this embodiment, the end surface of the winding structure 2 is directly scanned, which simplifies the steps of counting the wrinkle parameters of the step wrinkles 4, thereby facilitating shortening the detection cycle of the wrinkle degree of the battery cell, and further facilitating shortening the cycle of adjusting the processing technology of the battery cell.

[0139] In any of the above embodiments, after the step of forming the first battery cell and before the step of counting the step wrinkles 4 and the arc wrinkles 3 of the first battery cell, the battery cell processing method further includes:

[0140] The thickness of the first battery cell in the straight wall area 28 is detected and recorded as H1, and the maximum thickness of the first battery cell in the arc area 29 is detected and recorded as H2;

[0141] Calculate the wrinkle degree S of the first battery cell, S=(H2-H1) / H1;

[0142] When S≤0.05, the first battery cell is determined to be a qualified battery cell. At this time, it is no longer necessary to count the wrinkle parameters of the step wrinkles 4 and the arc wrinkles 3 of the first battery cell, and the first battery cell can be directly processed in batches according to the winding tension and hot pressing pressure of the first battery cell;

[0143] When S>0.05, the first battery cell is determined to be an unqualified battery cell, and the wrinkle parameters of the arc wrinkle 3 of the first battery cell at the arc area 29 are counted, and / or the wrinkle parameters of the step wrinkle 4 of the first battery cell are counted, and then the processing parameters of the battery cell are adjusted according to the wrinkle parameters, and the second battery cell is processed with the adjusted process parameters, and the above steps are repeated until the Nth battery cell is a qualified battery cell.

[0144] In this embodiment, before the step wrinkles 4 and the arc wrinkles 3 of the first battery cell, the wrinkle degree of the first battery cell is calculated, and whether the first battery cell is a qualified battery cell is determined according to the wrinkle degree. If the first battery cell is a qualified battery cell, there is no need to adjust the process parameters and batch production can be carried out directly, which reduces the risk of counting the arc wrinkles 3 and the step wrinkles 4 of the qualified battery cells, thereby shortening the battery cell detection cycle and reducing the complexity of the battery cell detection.

[0145] In any of the above embodiments, the winding tension F of the wound pole piece assembly 24 satisfies: 300g≤F≤800g, and the winding tension can specifically be 300g, 350g, 400g, 450g, 500g, 550g, 600g, 650g, 700g, 750g, 800g, etc.

[0146] If the winding tension is less than 300g, there is a risk of weak bonding between the positive pole piece 21, the negative pole piece 23 and the isolation film 22, resulting in a high risk of loosening inside the battery cell; if the winding tension is greater than 800g, the adjacent inner and outer pole piece assemblies 24 are tightly attached during the winding process. When arc wrinkles 3 or step wrinkles 4 appear on the inner layer, there is a high risk of step wrinkles 4 appearing at the same position on the outer layer, resulting in a high degree of wrinkling in the battery cell. Therefore, the winding tension of the winding pole piece assembly 24 is 300g~800g, which can enhance the bonding between the positive pole piece 21, the negative pole piece 23 and the isolation film 22, thereby reducing the risk of loosening inside the battery cell, and reducing the risk of wrinkles on the outer layer when wrinkles appear on the inner layer, which is beneficial to reducing the degree of wrinkles in the battery cell.

[0147] In any of the above embodiments, the hot pressing pressure P of the hot pressing winding structure 2 satisfies: 5t≤P≤12t, and the hot pressing pressure can be specifically 5t, 5.5t, 6t, 6.5t, 7t, 7.5t, 8t, 8.5t, 9t, 9.5t, 10t, 10.5t, 11t, 11.5t, 12t, etc.

[0148] If the hot pressing pressure is less than 5t, there is a risk of weak bonding between the positive pole piece 21, the negative pole piece 23 and the isolation film 22, resulting in a high risk of loosening inside the battery cell; if the hot pressing pressure is greater than 12t, the adjacent inner and outer pole piece assemblies 24 are closely attached during the hot pressing process. When arc wrinkles 3 or step wrinkles 4 appear in the inner layer, there is a high risk of step wrinkles 4 appearing at the same position in the outer layer, resulting in a high degree of wrinkling in the battery cell. Therefore, the hot pressing pressure of the hot pressing winding structure 2 is 5t~12t, which can enhance the bonding between the positive pole piece 21, the negative pole piece 23 and the isolation film 22, thereby reducing the risk of loosening inside the battery cell, and reducing the risk of wrinkles in the outer layer when wrinkles appear in the inner layer, which is beneficial to reducing the degree of wrinkles in the battery cell.

[0149] In summary, in one embodiment, Fig. 9 As shown, the steps of the battery cell processing method include:

[0150] Prepare a positive electrode sheet 21 and a negative electrode sheet 23;

[0151] The positive electrode sheet 21 and the negative electrode sheet 23 are stacked and rolled to form a electrode sheet assembly 24;

[0152] The pole piece assembly 24 is wound with a winding tension of F1 to form a winding structure 2 with an end face shape being a racetrack shape;

[0153] Hot pressing the wound structure 2 with a hot pressing pressure of P1;

[0154] Put the hot-pressed winding structure 2 into the housing 11;

[0155] Close the cover 12 on the housing 11 and fix it by welding;

[0156] Injecting electrolyte into the housing 1 through the injection port;

[0157] Sealing the liquid injection port to form a first battery cell;

[0158] Detect and calculate the wrinkle degree S of the first battery cell. If S>0.05, the first battery cell is an unqualified battery cell.

[0159] Counting the wrinkle parameters of the arc wrinkles 3 of the first battery cell, if the wrinkle parameters of the arc wrinkles 3 are greater than a first preset value, reducing the winding tension from F1 to F2, and / or reducing the hot pressing pressure from P1 to P2;

[0160] preparing a second battery cell with the adjusted winding tension and hot pressing pressure;

[0161] Detect and calculate the wrinkle degree S of the second battery cell. If S>0.05, the second battery cell is an unqualified battery cell.

[0162] Counting the wrinkle parameters of the arc wrinkle 3 of the second battery cell, if the wrinkle parameters of the arc wrinkle 3 are less than or equal to the first preset value, then counting the wrinkle parameters of the step wrinkle 4 of the second battery cell, if the wrinkle parameters of the step wrinkle 4 are greater than the second preset value, then reducing the hot pressing pressure from P2 to P3;

[0163] preparing a third battery cell by adjusting the winding tension and hot pressing pressure;

[0164] Repeat the above steps until the wrinkle degree S of the Nth battery cell is less than or equal to 0.05, and batch process the Nth battery cell with the winding tension and hot pressing pressure.

[0165] In another embodiment, if Fig.10 As shown, the steps of the battery cell processing method include:

[0166] Prepare a positive electrode sheet 21 and a negative electrode sheet 23;

[0167] The positive electrode sheet 21 and the negative electrode sheet 23 are stacked and rolled to form a electrode sheet assembly 24;

[0168] The pole piece assembly 24 is wound with a winding tension of F1 to form a winding structure 2 with an end face shape being a racetrack shape;

[0169] Hot pressing the wound structure 2 with a hot pressing pressure of P1;

[0170] Put the hot-pressed winding structure 2 into the housing 11;

[0171] Close the cover 12 on the housing 11 and fix it by welding;

[0172] Injecting electrolyte into the housing 1 through the injection port;

[0173] Sealing the liquid injection port to form a first battery cell;

[0174] Detect and calculate the wrinkle degree S of the first battery cell. If S>0.05, the first battery cell is an unqualified battery cell.

[0175] Counting the wrinkle parameters of the step wrinkles 4 of the first battery cell, if the wrinkle parameters of the step wrinkles 4 are greater than a second preset value, reducing the hot pressing pressure from P1 to P2;

[0176] The second battery cell is prepared with a winding tension of F1 and a hot pressing pressure of P2;

[0177] Detect and calculate the wrinkle degree S of the second battery cell. If S>0.05, the second battery cell is an unqualified battery cell.

[0178] Counting the wrinkle parameters of the step wrinkle 4 of the first battery cell, if the wrinkle parameter of the step wrinkle 4 is less than or equal to the second preset value, then counting the wrinkle parameters of the arc wrinkle 3 of the second battery cell, if the wrinkle parameter of the arc wrinkle 3 is greater than the first preset value, then reducing the winding tension from F1 to F2, and / or reducing the hot pressing pressure from P2 to P3;

[0179] The third battery cell is prepared with a winding tension of F2 and a hot pressing pressure of P3;

[0180] Repeat the above steps until the wrinkle degree S of the Nth battery cell is less than or equal to 0.05, and batch process the Nth battery cell with the winding tension and hot pressing pressure.

[0181] Specifically, refer to the battery cell processing parameter optimization process shown in Table 1. After the first battery cell is processed, the wrinkle degree S of the first battery cell is 0.2, which is greater than 0.05, then the first battery cell is an unqualified battery cell. At this time, the average length of the arc wrinkles 3 of the first battery cell is 2mm, and the number of step wrinkles 4 is 8, then the winding tension needs to be reduced from F1 to F2, and the hot pressing pressure needs to be reduced from P1 to P2. Then the second battery cell is processed with F2 and P2, and the wrinkle degree S of the second battery cell is measured to be 0.1, which is still greater than 0.05, then the second battery cell is an unqualified battery cell. At this time, the average length of the arc wrinkles 3 of the second battery cell is zero, that is, the arc wrinkles 3 disappear, and the number of step wrinkles 4 is 3, then the hot pressing pressure needs to be reduced to P3. The third battery cell is processed with F2 and P3, and the wrinkle degree S of the third battery cell is measured to be 0.02, which is less than 0.05, and the third battery cell is a qualified battery cell. At this time, the average length of the arc wrinkles 3 of the third battery cell is zero, that is, the arc wrinkles 3 disappear, and the number of step wrinkles 4 is 2, which meets the requirements. Then, the battery cells are subsequently processed in batches according to F2 and P3.

[0182] Table 1 Process parameter optimization process

[0183]

[0184] 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 processing a battery core, characterized in that: The processing method comprises: Preparing a positive electrode sheet (21) and a negative electrode sheet (23); The positive electrode sheet (21), the separator (22) and the negative electrode sheet (23) are stacked and rolled to form a sheet assembly (24); The pole piece assembly (24) is wound to form a wound structure (2), wherein the wound structure (2) comprises straight wall areas (28) arranged relatively to each other along the thickness direction thereof, adjacent straight walls are connected by arc areas (29), and the straight wall areas (28) and the arc areas (29) form a racetrack-shaped structure; Hot pressing the wound structure (2); placing the hot-pressed coiled structure (2) into the housing (1); injecting electrolyte into the housing (1) through the liquid injection port; Sealing the liquid injection port to form a first battery cell; The wrinkle parameters of the arc wrinkles (3) of the first battery cell at the arc region (29) are counted; when the wrinkle parameters of the arc wrinkles (3) are greater than a first preset value, the winding tension of the pole piece assembly (24) is reduced, and the second battery cell is processed with the adjusted winding tension, and / or the hot pressing pressure of the hot pressing winding structure (2) is reduced, and the second battery cell is processed with the adjusted hot pressing pressure.

2. The method for processing a battery cell according to claim 1, characterized in that: The step of counting wrinkle parameters of the arc-shaped wrinkles (3) of the first battery cell at the arc-shaped area (29) comprises: Disassembling the first battery cell and removing the winding structure (2) inside the first battery cell; Unfolding the wound structure (2) of the first battery cell; The wrinkle parameters of the arc-shaped wrinkles (3) are counted.

3. The method for processing a battery cell according to claim 2, characterized in that: The step of counting the wrinkle parameters of the arc-shaped wrinkles (3) comprises: Performing a CT scan on the unfolded winding structure (2) and transmitting the scanned effect image to a central control system; The central control system identifies the wrinkle area in the scanning effect image and counts the wrinkle parameters of the wrinkle area.

4. The method for processing a battery cell according to claim 1, characterized in that: The step of counting wrinkle parameters of the arc-shaped wrinkles (3) of the first battery cell at the arc-shaped area (29) comprises: Disassembling the first battery cell and removing the winding structure (2) inside the first battery cell; Performing CT scanning on the end surface of the winding structure (2) and transmitting the scanning effect image to the central control system; The central control system identifies the number of fold distribution layers in the scanning effect diagram and the fold parameters of the arc-shaped folds (3).

5. The method for processing a battery cell according to any one of claims 1 to 4, characterized in that: The number N1 of the arc-shaped wrinkles (3) satisfies: when N1 ≥ 6, the arc-shaped wrinkles (3) are determined to be small wrinkles, and the hot pressing pressure of the coiled structure (2) is reduced; When the number N1 of the arc-shaped wrinkles (3) satisfies: 2<N1<6, the arc-shaped wrinkles (3) are determined to be large wrinkles, and the winding tension of the pole piece assembly (24) is reduced.

6. The method for processing a battery cell according to claim 1, characterized in that: The pole piece assembly (24) comprises a lithium-embedded region (26) and a non-lithium-embedded region (27); and on the winding structure (2), a step fold (4) is present at the junction of the lithium-embedded region (26) and the non-lithium-embedded region (27); Before or after counting the wrinkle parameters of the arc-shaped wrinkles (3) of the first battery cell at the arc-shaped area (29), the processing method of the battery cell comprises: The wrinkle parameters of the step wrinkles (4) are counted, and when the wrinkle parameters of the step wrinkles (4) are greater than a second preset value, the hot pressing pressure of the winding structure (2) is reduced, and the second battery cell is processed with the adjusted hot pressing pressure.

7. The method for processing a battery cell according to claim 6, characterized in that: The step of calculating the fold parameters of the step fold (4) comprises: Disassembling the first battery cell and removing the winding structure (2) inside the first battery cell; Unfolding the wound structure (2) of the first battery cell; The fold parameters of the step fold (4) are counted.

8. The method for processing a battery cell according to claim 6, characterized in that: The step of calculating the fold parameters of the step fold (4) comprises: Disassembling the first battery cell and removing the winding structure (2) inside the first battery cell; Performing CT scanning on the end surface of the winding structure (2) and transmitting the scanning effect image to the central control system; The central control system identifies the wrinkle parameters of the step wrinkles (4) in the scanning effect image.

9. The method for processing a battery cell according to claim 6, characterized in that: After the step of forming the first battery cell, the battery cell processing method includes: Detecting the thickness of the first battery cell in the straight wall area (28) and recording it as H1, and detecting the maximum thickness of the first battery cell in the arc area (29) and recording it as H2; Calculate the wrinkle degree S of the first battery cell, S=(H2-H1) / H1; When S≤0.05, the first battery cell is determined to be a qualified battery cell, and the first battery cell is processed in batches with the winding tension and the hot pressing pressure; When S>0.05, the first battery cell is determined to be an unqualified battery cell, and the wrinkle parameters of the arc wrinkles (3) of the first battery cell at the arc area (29) are counted, and / or the wrinkle parameters of the step wrinkles (4) of the first battery cell are counted.

10. The method for processing a battery cell according to any one of claims 1 to 4 and 6 to 9, characterized in that: The winding tension F of the pole piece assembly (24) satisfies: 300g≤F≤800g; The hot pressing pressure P of the winding structure (2) is reduced to meet the following conditions: 5t≤P≤12t.

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