A laminated cell and a battery

Abstract

The utility model discloses a kind of laminated core and battery, the battery includes the pole piece and diaphragm of alternative stacking and by hot-pressing composite, and two adjacent pole pieces polarity opposite and are separated by diaphragm, one side of pole piece is equipped with two recesses, one tab is respectively extended from each recess by two adjacent pole pieces, the outside of each tab is welded with an adapter tab, diaphragm is cut after being at the edge of each recess, and is used to be placed in corresponding recess after corresponding tab is bent. The laminated core of the utility model bends and welds tab hidden in recess, so that head space utilization is high, improve battery energy density, improve battery performance, while lithium battery head space has the support of core body hardness, the risk resistance of tab is greatly improved, improve the service life and safety performance of battery.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, specifically to a stacked cell and battery. Background Technology

[0002] Lithium batteries consist of stacked cells and a casing. The stacked cells require pre-welding of the soft tabs, followed by transfer welding to a slightly harder hard tab. Then, the bent soft and hard tabs are placed in the head space of the lithium battery near the tabs. Finally, the hard tab is connected to the casing. When the power supply terminals of power-consuming devices are connected to the positive and negative terminals of the lithium battery casing, the lithium battery can provide power to the power-consuming devices. However, batteries manufactured in this way have the following drawbacks: (1) Low utilization of the head space, resulting in a significant loss of energy density and affecting performance. (2) In some applications, the head space of the lithium battery lacks the support of the cell's rigidity. Under unavoidable external force, the resulting vibration may cause the tabs to break, leading to battery power failure and even the risk of internal short circuits.

[0003] Existing conventional hard-shell batteries are manufactured by first processing stainless steel sheets or other materials into an upper cover and a lower housing cavity, then placing the battery cell into the lower housing cavity, positioning the upper cover and lower housing cavity separately, pressing the upper cover onto the lower housing cavity, and finally forming a seal through laser welding. During the assembly and welding process of the upper cover and lower housing cavity, positioning and handling errors can easily cause misalignment, affecting welding reliability and product yield; furthermore, this structure has a high processing cost. Utility Model Content

[0004] This utility model addresses the problems in the prior art by disclosing a stacked cell and battery. This utility model hides the tab bending and welding in the groove, which makes high utilization of the head space, improves the battery energy density, and enhances the battery performance. At the same time, the head space of the lithium battery is supported by the rigidity of the cell body, which greatly improves the tab's resistance to risk, thereby improving the battery's service life and safety performance.

[0005] This utility model is achieved through the following technical solution:

[0006] This utility model first provides a stacked battery cell, including alternately stacked electrodes and a separator that are composited by hot pressing. The two adjacent electrodes have opposite polarities and are separated by the separator. Two grooves are provided on one side of the electrodes. In each groove, an electrode tab extends from the two adjacent electrodes respectively. The outside of each electrode tab is welded to an adapter tab. The separator is cut at the edge of each groove and is used to be bent along with the corresponding electrode tab and placed in the corresponding groove.

[0007] As a further embodiment, the electrode includes a positive electrode and a negative electrode. The positive electrode has a first positive groove and a second positive groove of the same size on one side, and a positive electrode tab extends from the first positive groove.

[0008] As a further option, the width of the positive electrode tab is X1, and the width of the first groove of the positive electrode is X2. X1 and X2 satisfy the relationship: 0.2mm≤(X2-X1) / 2≤0.5mm.

[0009] As a further embodiment, a negative electrode plate is provided on one side with a first negative electrode groove and a second negative electrode groove of the same size, and a negative electrode tab extends from the first negative electrode groove. The width of the negative electrode tab is the same as the width of the positive electrode tab, and the depth of the first negative electrode groove is greater than the depth of the first positive electrode groove.

[0010] As a further option, the width of the first groove of the negative electrode is X5, the width of the negative electrode tab is X4, and the size of the negative electrode sheet covering the positive electrode sheet is r1. Then X4 and X5 satisfy the relationship: 0.2mm≤(X5-X4+2*r1) / 2≤0.5mm.

[0011] As a further embodiment, the distance between the diaphragm cutting position and the inner wall of the second negative electrode groove is X7, where 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the second negative electrode groove, X4 is the width of the adapter tab, and the cutting height of the diaphragm cutting position is less than or equal to the distance to the root of the second negative electrode groove.

[0012] As a further option, a gap is provided between the diaphragm cutting position and the negative electrode sheet, and the covering size of the diaphragm and the negative electrode sheet is r2, where r2≥0.1mm.

[0013] This utility model also provides a battery in which the stacked cells are located inside the casing.

[0014] As a further embodiment, the housing includes an integral upper shell and a lower shell, the upper shell being a rectangular plate and the lower shell being a rectangular shell, with the included angle between the two ranging from 45° to 270°, and the upper shell and the lower shell being sealed together after being pressed together.

[0015] As a further embodiment, a bending groove is formed at the junction of the upper and lower shells, and the depth C1 of the bending groove and the thickness K of the shell satisfy the following relationship: 0.3≤C1 / K≤0.7.

[0016] The features and beneficial effects of this utility model are as follows:

[0017] The laminated battery cell:

[0018] (1) The stacked cell of this utility model hides the tabs by bending and welding them in the groove. The head space of the lithium battery is supported by the hardness of the cell body, which greatly improves the tabs' resistance to risk and enhances the battery's service life and safety performance.

[0019] (2) The stacked cell structure provided by this utility model has high head space utilization, improves battery energy density, and enhances battery performance.

[0020] (3) This utility model forms a stacked core by hot pressing, that is, by pre-heating the separator and the electrode, the hidden dangers of separator wrinkles and electrode powder shedding are completely eliminated. At the same time, the internal structure of the battery is completely stable, which can better improve the product yield.

[0021] The battery:

[0022] (1) The battery of this utility model adopts an integrated structure, which eliminates the positioning of the upper cover plate and the lower receiving cavity, as well as the handling action of the upper cover plate. It can avoid the influence of the positioning error of the upper cover plate and the lower receiving cavity and the handling error of the upper cover plate on the assembly welding. It can effectively solve the offset problem when the upper cover plate and the lower receiving cavity are assembled and welded, and can ensure the welding reliability and product yield, while reducing the manufacturing cost of hard-shell battery.

[0023] (2) When the stacked core of this utility model is placed inside the shell, it can be abutted against the inside of the shell on all sides, which can maximize the battery capacity and greatly improve the battery capacity and capacity density. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the positive electrode structure according to an embodiment of the present invention;

[0026] Figure 2 for Figure 1 Sectional view along axis AA;

[0027] Figure 3 This is a schematic diagram of the negative electrode sheet according to an embodiment of the present utility model;

[0028] Figure 4 For this Figure 3 BB-direction sectional view;

[0029] Figure 5 This is a schematic diagram illustrating the manufacturing process of the electrode sheet according to an embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram of the Z-stack single-sided positive electrode tail structure according to an embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram of the Z-stack single-sided negative electrode termination structure according to an embodiment of the present invention;

[0032] Figure 8 This is a schematic diagram of the structure of the thermal composite laminate described in an embodiment of the present invention;

[0033] Figure 9 This is a schematic diagram of the stacked battery cell before bending, as described in this embodiment of the utility model.

[0034] Figure 10 This is a schematic diagram of the electrode tab pre-welding according to an embodiment of the present utility model;

[0035] Figure 11 This is a schematic diagram of the electrode tab cutting process described in an embodiment of the present invention;

[0036] Figure 12 This is a schematic diagram of the stacked battery cell after bending according to an embodiment of the present invention;

[0037] Figure 13 for Figure 12 CC-direction sectional view;

[0038] Figure 14 for Figure 13 Enlarged view of the central X-section;

[0039] Figure 15 This is a schematic diagram of the adapter tab structure described in an embodiment of the present utility model;

[0040] Figure 16 This is a schematic diagram of the housing described in an embodiment of the present utility model;

[0041] Figure 17 This is a side view of the housing described in an embodiment of the present utility model;

[0042] Figure 18 This is a schematic diagram of the bending groove described in an embodiment of the present utility model;

[0043] Figure 19 This is a flowchart of the shell manufacturing method according to an embodiment of the present utility model;

[0044] Figure 20 This is a box plot of the energy density of Embodiment 1 of this utility model;

[0045] Figure 21 This is a box plot of the energy density of Embodiment 2 of this utility model;

[0046] Figure 22 This is a box plot of the energy density of Embodiment 3 of this utility model;

[0047] Figure 23This is a box plot of the energy density of Embodiment 4 of this utility model;

[0048] Figure 24 This is a cross-sectional view of the battery described in an embodiment of the present invention;

[0049] Figure 25 for Figure 24 Enlarged view of the Y-section.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1-Positive electrode sheet; 11-First positive electrode groove; 12-Second positive electrode groove; 13-Positive electrode tab; 14-Positive electrode active material; 15-Positive electrode foil; 2-Negative electrode sheet; 21-First negative electrode groove; 22-Second negative electrode groove; 23-Negative electrode tab; 24-Negative electrode foil; 25-Negative electrode active material; 3-Separator; 4-Welding position; 5-Single-sided positive electrode sheet; 6-Single-sided negative electrode sheet; 7-Adapter tab; 8-Taper adhesive; 9-Shell; 91-Upper shell; 92-Lower shell; 93-Electrical post; 94-Injection hole; 95-Bending groove; A-Removal area; B-Positive electrode tab bending position; C-Negative electrode tab bending position; D-Pre-welding position; E-Cutting position; F-First groove; G-Second groove. Detailed Implementation

[0052] To facilitate understanding of this utility model, a more comprehensive description of this utility model will be provided below, along with embodiments of this utility model, but this does not limit the scope of this utility model.

[0053] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0054] Existing laminated battery cells, when the tabs and adapter tabs are welded and bent before being placed into the casing, occupy a large space within the casing. This results in a smaller volume of laminated cells installed within a casing of the same volume, thus reducing the battery's energy density. Furthermore, because the bent portion extends beyond the end face of the cell's electrode and is located in the head area of ​​the casing, this area lacks other supporting components besides the bent tab area. When this part of the casing is subjected to mechanical abuse conditions such as rolling or dropping, or is subjected to external impacts, the lack of support makes it susceptible to impact force, leading to tab breakage and ultimately cell failure. To maximize cell energy density, using tab bending to reduce the space occupied by the tabs is a common industry practice. However, we have verified through extensive testing how to bend the tabs effectively, reduce the space occupied by the bent portion, and simultaneously improve the overall energy density of the battery. In addition, the battery includes not only the stacked cells but also the casing. Existing casings are all split structures. After the stacked cells are inserted into the casing, they need to be connected to the casing through tabs. Therefore, there are requirements for the installation position and size of the stacked cells. In order to maximize the use of the casing space, the size of the stacked cells is generally set to be large enough, which increases the difficulty of inserting the stacked cells into the casing. When inserting the stacked cells into the casing, an external limiting mechanism is generally required to limit the casing and the stacked cells before inserting the stacked cells into the casing. Then, the upper cover plate and the lower receiving cavity are limited to ensure that the positions of the upper and lower structures are relatively stable. Especially during the welding process, since the upper cover plate and the lower receiving cavity are welded in a circumferential direction, the machine avoidance problem also needs to be considered. Therefore, the entire production line requires a lot of supporting equipment and has very high precision requirements. In order to solve the above problems, this application proposes a battery structure, including improvements to the stacked cells and the casing.

[0055] A type of laminated battery cell, such as Figures 1 to 15 As shown, the device includes alternately stacked electrodes and a separator 3, which are composited by hot pressing. Adjacent electrodes have opposite polarities and are separated by the separator 3. Each electrode has two grooves on one side, with an electrode tab extending from each of the two adjacent electrodes within each groove. The exterior of each electrode tab is welded to a connecting electrode tab 7. The separator 3 is cut at the edge of each groove and then bent to fit within the corresponding groove. The distance between the two grooves is greater than 1 mm.

[0056] The stacked cell structure provided by this invention achieves high utilization of the head space, increases battery energy density, and improves battery performance. By concealing the tab bending and welding within the grooves, the head space of the lithium battery is supported by the rigidity of the cell body, significantly enhancing the tab's resilience and improving battery lifespan and safety.

[0057] The positive electrode foil 15 is coated with positive electrode active material 14 on both sides to form a positive electrode sheet 1. Since the improvement in this application is only a structural improvement, both the foil and the active material adopt existing technologies, such as aluminum foil and lithium nickel cobalt manganese oxide.

[0058] The positive electrode plate 1 has a first positive electrode groove 11 and a second positive electrode groove 12 on one side, and a positive electrode tab 13 extends from the first positive electrode groove 11. In the height direction, the positive electrode tab 13 consists of two parts: a first part is located within the first positive electrode groove 11 with a height of Y1, and a second part extends from the first positive electrode groove 12 along the height direction with a height of Y2. The total height of the positive electrode tab is Y1 + Y2. A schematic diagram of the positive electrode plate structure is shown below. Figure 1 As shown: In the width direction, the width of the positive electrode tab 13 is X1, and the width of the first positive electrode groove 11 is X2. X1 and X2 satisfy the relationship: 0.2mm ≤ (X2-X1) / 2 ≤ 0.5mm. If (X2-X1) / 2 is too small, when removing the positive electrode active material 14, it should be ensured that there is no residue of positive electrode active material 14 on the obtained positive electrode tab 13. Otherwise, because the active material is more brittle than the foil, it will cause the positive electrode tab to be difficult to bend or to break during the subsequent bending process. The methods for removing active material include, but are not limited to, laser cleaning, scraping, or solvent removal. The minimum theoretical removal accuracy in the industry is currently 0.1mm. After repeated experiments, when this data is greater than or equal to 0.2mm, the process capability can be fully guaranteed, which is convenient for manufacturing. If (X2-X1) / 2 is too large, too much active material will be lost, which will reduce the electrode capacity. The width of the second positive electrode groove 12 is X3, and X3 and X2 satisfy the relationship: X3-X2=0. The height of the second positive electrode groove 12 is Y3, and Y3 and Y2 satisfy the relationship: Y3-Y2=0, that is, the dimensions of the first positive electrode groove and the second positive electrode groove are the same.

[0059] The negative electrode foil 25 is coated with negative electrode active material 24 on both sides to form a positive electrode sheet 2. Since the improvement in this application is only a structural improvement, both the foil and the active material adopt existing technologies, such as copper foil and lithium titanate.

[0060] The negative electrode plate 2 has a first negative electrode groove 21 and a second negative electrode groove 22 on one side, and a negative electrode tab 23 extends from the first negative electrode groove 21. The structural schematic diagram of the negative electrode plate 2 is shown below. Figure 2 As shown. In the width direction, the width of the negative electrode tab 23 is X4, preferably X1 = X4, that is, the widths of the positive and negative electrode tabs are the same. The width of the first negative electrode groove 21 is X5, and the size of the negative electrode sheet 2 covering the positive electrode sheet 1 is r1. Then X4 and X5 satisfy the relationship: 0.2mm ≤ (X5-X4+2*r1) / 2 ≤ 0.5mm. If (X5-X4+2*r1) / 2 is too small, when removing the negative electrode active material 25, it should be ensured that there is no negative electrode active material 25 residue on the obtained negative electrode tab 23. Otherwise, because the negative electrode active material is more brittle than the foil, it will cause the negative electrode tab to be difficult to bend or to break during the subsequent bending process. If (X2-X1) / 2 is too large, too much negative electrode active material will be lost, and the size of the negative electrode sheet 2 covering the positive electrode sheet 1 will be too small, which will reduce the electrode capacity.

[0061] The width of the second negative electrode groove 21 is X6, and X6 and X5 satisfy the relationship: X6-X5=0. In the height direction, the negative electrode tab 23 consists of two parts: the first part is inside the first negative electrode groove 21, with a height of Y4; the second part extends out of the first negative electrode groove 21 along the height direction, with a height of Y5. The total height of the negative electrode tab 23 is Y4+Y5. The height of the second negative electrode groove 22 is Y6, and Y6 and Y5 satisfy the relationship: Y6-Y5≥0; the relationship between Y5 or Y6 and Y1 or Y3 satisfies: Y6-Y1=r1, Y4-Y3=r1. Y6-Y5≥0: The Y6 part is the pre-welded area; after the tab is bent later, its height cannot exceed the battery body thickness H1, otherwise the battery will be too thick. Y6-Y1=r1, Y4-Y3=r1: In the thickness direction of the battery, the distance between the root of the negative electrode groove and the root of the tab is smaller than the distance between the root of the positive electrode groove and the root of the tab, specifically the smaller dimension is r1; in the height direction, the depth of the negative electrode groove is smaller than that of the positive electrode groove, specifically the smaller dimension is r1. This design can meet the size requirements of the positive and negative electrode sheets.

[0062] This utility model provides a method for manufacturing a laminated battery cell (hereinafter referred to as "laminated cell"), comprising the following steps:

[0063] S1. The specific methods for making the positive and negative electrode plates are as follows:

[0064] like Figure 5 As shown, the manufacturing methods for the positive and negative electrodes are the same. Taking the positive electrode as an example, the specific method is as follows:

[0065] S11. The positive electrode sheet 1 coated with positive active material 15 on the foil 14 is die-cut into the designed shape by a hardware mold. The die-cut positive electrode sheet 1 has a positive electrode tab 13.

[0066] S12. Remove the positive active material 15 near the positive electrode tab 13 to expose the foil 14 in the removal area A, thus creating a tab empty foil area.

[0067] S13. Along the extension direction of the positive electrode tab 13, while preserving the integrity of the positive electrode tab 13, cut off both sides of it. At this time, the length of the positive electrode tab 13 becomes longer.

[0068] S14. Using a metal mold or laser die-cutting method, the positive electrode piece 1 that mates with the negative electrode tab 23 is cut off to form the positive electrode second groove 12.

[0069] S2. The positive electrode 1, negative electrode 2, and separator 3 are alternately stacked and then hot-pressed to form a laminated battery cell.

[0070] The hot-pressing composite method includes three specific methods:

[0071] The first method is the Z-stacking method: the separator 3 is pulled in a Z-shaped reciprocating motion by a movable stacking stage, and the positive electrode 1 and negative electrode 2 are placed alternately to complete the stacking. The tension of the separator 3 is dynamically adjusted (5-15N), and the positioning accuracy of the robot arm is ≤0.3mm, forming a "positive electrode-separator-negative electrode-separator" cycle structure.

[0072] The second method is the integrated cutting and stacking approach. This refers to the integration of three types of machines: electrode die-cutting / laser cutting, Z-shaped stacking machine, and adhesive-coated hot press machine. The integrated cutting and stacking machine simultaneously feeds in the positive and negative electrodes and the separator, folding them in a Z-shape under the action of the main stacking table or swing arm. After stacking to the set number of electrodes, the separator is cut and adhesive-coated, and then hot-pressed into a stacked battery cell. The schematic diagrams of the Z-stacking structure for both methods are shown below. Figures 6-7 As shown, the laminated cell can be either single-sided negative electrode or single-sided positive electrode.

[0073] like Figure 8 As shown, the third method involves first thermally bonding the positive or negative electrode sheet with the separator, and then stacking them in a specific order. This method, which forms the stacked core through hot pressing, completely eliminates the risks of separator wrinkles and electrode powder shedding by pre-thermally thermally bonding the separator and electrode sheets. Simultaneously, it ensures complete stability of the battery's internal structure, thus improving product yield.

[0074] S3. The positive electrode tab 13 and negative electrode tab 23 of the prepared stacked core are pre-welded against the edge of the separator 3 so that each layer of electrode is connected by the tab.

[0075] S31. Pre-weld and cut the positive electrode tab 13 and negative electrode tab 23. The pre-welding direction is along the extension direction of the tab, and the edge of the weld near the electrode connects with the edge of the diaphragm 3. The total thickness of the stacked core body is H1, and the pre-welding height Y8 should satisfy Y8≤H1. Afterwards, cut off the remaining tabs. Figure 9 and Figure 10 As shown.

[0076] S32. Since this design includes a positive electrode tab 13 and a negative electrode tab 23, the bending methods for the positive electrode tab bending position B and the negative electrode tab bending position C are the same. For ease of description, the negative electrode sheet is used as an example here.

[0077] In order for the negative electrode tab 23 to be placed at the negative electrode tab bending position C after bending, the diaphragm 3 at the negative electrode tab bending position C needs to be cut first.

[0078] The distance between the separator cutting position and the inner wall of the second negative electrode groove 21 is X7. X7 needs to meet the design value for the coverage of the separator 3 and the negative electrode sheet 2, and is generally taken as 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the second negative electrode groove 21 and X4 is the width of the adapter tab 7. The cutting height of the separator cutting position is Y7, where Y7≤Y4+r2, and Y4+r2 is the maximum cutting height of the separator to the root of the groove. If it is greater than this value, the size of the negative electrode covered by the separator will be smaller, reducing the safety of the cell. If it exceeds Y4, it will cut into the electrode body. Preferably, the cutting height Y7 should correspond to the bending size, but cannot be greater than the thickness of the battery body, i.e., Y5≤Y7≤H1.

[0079] A gap is provided between the diaphragm cutting position and the negative electrode 2. The covering dimension of the diaphragm 3 and the negative electrode 2 is r2, where r2 ≥ 0.1 mm. This satisfies the processing accuracy and prevents the negative and positive electrodes from short-circuiting and igniting after the diaphragm 3 shrinks due to heat. A schematic diagram of the stacked core formed using the above method is shown below. Figure 12 As shown in the figure. Among them, the groove formed by the positive electrode first groove 11 and the negative electrode second groove 21 is collectively referred to as the first groove F, and the groove formed by the negative electrode first groove 22 and the positive electrode second groove 12 is collectively referred to as the second groove G.

[0080] S4. After pre-soldering each layer of electrode sheets on the stacked core, connect it to an adapter tab 7. Preferably, the positive adapter tab is made of aluminum and the negative adapter tab is made of nickel-plated copper. The adapter tabs should be made of metal materials similar to the stacked core material to reduce the potential difference between the positive and negative electrodes.

[0081] The adapter tab 7 is an aluminum or nickel tab with a hardness slightly greater than that of the positive or negative electrode foil, and is fitted with tab adhesive 8. One end of the adapter tab 7 is a welding position, which is connected to the tab of the stacked core through ultrasonic welding or laser welding, so that each layer of the stacked core is connected to the adapter tab. In the thickness direction projection, the projection of the pre-welded stacked core tabs can completely cover the projection of the welding position of the adapter tab 7, ensuring that the stacked core tabs have sufficient material to connect with the adapter tab, guaranteeing a sufficiently high current density. Simultaneously, since current flows through the tabs during re-discharge, the heat at the tabs is significantly concentrated; a sufficiently large welding area can alleviate heat concentration and reduce the possibility of battery thermal failure. That is, the height of the welding position of the adapter tab 7 is Y10, and Y10, Y8, and H1 satisfy the relationship: Y10≤Y8≤H1. The width of the tab is X9. When the adapter tab 7 is connected to the positive electrode 1, X9 and X2 or X3 satisfy the following relationship: 0≤(X9-X2) / 2≤0.5mm or 0≤(X9-X3) / 2≤0.5mm; when the adapter tab 7 is connected to the negative electrode 2, X9 and X5 or X6 satisfy the following relationship: 0≤(X9-X5) / 2≤0.5mm or 0≤(X9-X6) / 2≤0.5mm.

[0082] For ease of understanding, the details are described using the adapter tab 7 and the positive tab 13 as an example. After connecting the adapter tab 7 and the positive tab 13, the tab is bent along the root of the separator cut and inserted into the first groove F. Part of the tab adhesive 8 is also inserted into the first groove F. The ratio of the inserted portion Y91 to the exposed portion Y92 satisfies the following relationship: 0 ≤ Y91 / Y92 ≤ 0.3. If Y91 / Y92 < 0, after the stacked core is placed in the casing and sealed, too much tab adhesive is exposed, occupying a large space and hindering the improvement of battery energy density. If Y91 / Y92 > 0.3, that is, more tab adhesive is inserted into the first groove than is used for sealing, the height of the first groove will increase, reducing battery energy density, and the reliability of the sealing cannot be guaranteed. The bending process requires two folds: a first fold followed by a second fold. The positive electrode tab 13 and the separator 3 are bent together in the first fold. The positive electrode tab 13 and the adapter tab 7 are bent together in the opposite direction of the first fold. Then, the adapter tab 7 is bent at a set angle away from the stacked core and led out. The set angle is less than 180°. The height Y7 of the first groove G is composed of the height Y91 of the tab adhesive partially inserted into the first groove, the height of the first fold, and the height of the second fold. The height of the first fold = thickness of the positive electrode foil * number of positive electrode layers + thickness of the separator * number of separator layers; the height of the second fold = thickness of the positive electrode foil * number of positive electrode layers + thickness of the adapter tab. Therefore, the total height Y7 of the first groove = Y91 + thickness of the positive electrode foil * number of positive electrode layers * 2 + thickness of the separator * number of separator layers + thickness of the adapter tab. The bending method of the negative electrode is the same as that of the positive electrode and will not be described again here.

[0083] This utility model provides a battery, such as Figures 16 to 25 As shown, the battery includes the stacked battery cell and its external housing 9. The housing 9 comprises an integral upper housing 91 and a lower housing 92. The upper housing 91 is a rectangular plate, and the lower housing 92 is a rectangular shell, with the included angle between them ranging from 45° to 270°. The upper housing 91 and the lower housing 92 are sealed together after being pressed. Compared with the traditional conventional hard-shell battery structure, the battery structure provided by this utility model eliminates the need for positioning the upper cover plate and the lower receiving cavity, as well as the handling of the upper cover plate. This avoids the impact of positioning errors and handling errors of the upper cover plate and the lower receiving cavity on the assembly welding, effectively solving the misalignment problem during the assembly welding of the upper cover plate and the lower receiving cavity, ensuring welding reliability and product yield, while reducing the manufacturing cost of hard-shell batteries.

[0084] In one embodiment, the lower shell 92 is provided with an electrode post 93 and a liquid injection hole 94 on any surface other than the surface with the largest area. Preferably, the electrode post 93 is welded to the lower shell 92.

[0085] A bending groove 95 is formed at the junction of the upper shell 91 and the lower shell 92 to facilitate folding of the upper shell 91 and the lower shell 92. The depth C1 of the bending groove 95 and the thickness K of the shell satisfy the following relationship: 0.3≤C1 / K≤0.7. If C1 / K<0.3, the bending groove is too shallow, the material deformation resistance is too large during folding, making it difficult to bend, resulting in high operational difficulty, inconsistent angles, and poor product consistency. If C1 / K>0.7, there is too little remaining material at the joint, resulting in insufficient connection strength and easy fatigue cracking during repeated folding. The preferred range of C1 / K is 0.4~0.6, which can well balance foldability and strength. Example: If the shell thickness K=2mm, then C1=0.8~1.2mm. In the width direction, the bending groove 95 has a width of K1, and this groove is symmetrically arranged along the outer wall of the shell, with K1 ≥ 2K, ensuring stress dispersion during processing. If K1 is too small, stress concentration will occur during processing, reducing the material's fatigue strength and increasing the risk of cracking. Folding is performed along the K1 / 2 point of the bending groove, that is, along the outer wall of the lower receiving cavity, meaning the center line of the bending groove coincides with the outer wall of the shell. This ensures alignment and smooth operation of the upper cover and the lower receiving cavity during folding. The upper cover rotates around the outer wall of the lower receiving cavity (K / 2 axis), achieving precise and controllable opening and closing trajectory.

[0086] The assembly method of the housing 9 and the laminated battery cell is as follows:

[0087] Step 1: First, stamp the shell into a one-piece structure, and the included angle V between the upper shell 91 and the lower shell 92 is 45-270 degrees;

[0088] Step 2: Machining a bending groove 95 at the junction of the upper shell 91 and the lower shell 92 to facilitate folding; the specific process is as follows: determine the thickness of the shell 9 as K, calculate the depth C1 of the bending groove 95, preferably C1-0.5K, set the groove width K1≥2K, machine the bending groove along the center line of the shell, verify the position of the folding axis K1 / 2, and conduct multiple folding tests.

[0089] Step 3: Connect the positive electrode tab 13 of the laminated cell to the terminal 93 of the housing, and connect the negative electrode tab 23 to the housing 9.

[0090] Step 4: Place the stacked battery cells into the lower shell 92, and flip the upper shell 91 onto the lower shell 92.

[0091] Step 6: Form a seal by laser welding the three edges of the housing.

[0092] The casing can be made of conductive metals such as aluminum, steel, stainless steel, nickel, copper or magnesium alloy, or aluminum-plastic film.

[0093] Comparative Example 1

[0094] The casing 9 is an aluminum-plastic film casing. The average energy density of the battery cell is calculated to be 784.98Wh / L, based on the cell model 566875 (total cell thickness 5.6mm, width 68mm, height 75mm).

[0095] Example 1

[0096] The casing 9 is an aluminum-plastic film casing, and the stacked battery cell has a two-tab structure (one positive tab and one negative tab). The tab adhesive is inserted into the groove to a depth of 1.6mm, i.e., Y91 = 1.6mm. The calculated average energy density of the battery cell is 799.42Wh / L, and the battery capacity can be increased by 1.84%. Capacity data before and after the experiment are shown in Table 1 below. Therefore, the structure of this invention can completely improve the capacity of two-tab structure batteries. The box plot is shown below. Figure 20 As shown.

[0097] Example 2

[0098] The casing 9 is an aluminum-plastic film casing, and the stacked cells have a three-tab structure (one positive tab and two negative tabs, or one negative tab and two positive tabs). The tab adhesive is inserted into the groove to a depth of 1.6mm, i.e., Y91 = 1.6mm. The calculated average energy density of the cells is 791.15Wh / L, and the battery capacity can be increased by 0.9%. Therefore, this invention can significantly improve the capacity of batteries with two-tab structures, as shown in the box plot. Therefore, this invention can significantly improve the capacity of batteries with three-tab structures, as shown in the box plot. Figure 21 As shown.

[0099] Table 1

[0100]

[0101]

[0102]

[0103] Since the battery cell model used in this calculation is a relatively small battery, the larger the battery model, the higher the capacity improvement of this invention. In summary, the structure of this invention can increase battery capacity. Based on the calculation data for the tab structure and the three-tab structure, the tab structure achieves greater capacity gains and is less difficult to manufacture than the three-tab structure. Therefore, the tab structure is preferred in this invention.

[0104] Comparative Example 2

[0105] The casing is made of stainless steel or other metal materials, and the tabs of the stacked cores are directly welded to the casing. Calculations are performed using cell model 566875 (total cell thickness 5.6mm, width 68mm, height 75mm). The average energy density is calculated to be 785.62Wh / L.

[0106] Example 3

[0107] The casing material is the same as in Comparative Example 2, and the tabs of the stacked cells are directly welded to the casing. The stacked cells have a three-tab structure (one positive tab and two negative tabs or one negative tab and two positive tabs). Calculations are performed using cell model 566875 (total cell thickness 5.6mm, width 68mm, height 75mm), where the tab adhesive is inserted into the groove to a depth of 1.6mm, i.e., Y91 = 1.6mm. The calculated average cell energy density is 801.84Wh / L, and the battery capacity can be increased by 2.06%. Therefore, the structure of this invention can completely improve the capacity of two-tab structure batteries. The box plot is shown below. Figure 22 As shown.

[0108] Example 4

[0109] The casing material is the same as in Comparative Example 2, and the tabs of the stacked core are directly welded to the casing. The stacked core cell has a two-tab structure (one positive tab and one negative tab), and calculations are performed using cell model 566875 (total cell thickness 5.6mm, width 68mm, height 75mm). The tab adhesive is inserted into the groove to a depth of 1.6mm, i.e., Y91 = 1.6mm. The calculated average cell energy density is 794.84Wh / L, and the battery capacity can be increased by 1.5%. Therefore, the structure of this utility model can completely improve the capacity of a three-tab battery. The box plot is shown below. Figure 23 As shown.

[0110] The data for Examples 3 and 4 are shown in Table 2.

[0111] Table 2

[0112]

[0113]

[0114] As described above, the structure of this utility model can improve battery capacity. Based on the calculation data of the two-tab and three-tab structures, the two-tab structure yields a greater capacity gain and is less difficult to manufacture than the three-tab structure; therefore, the two-tab structure is preferred in this utility model. Since the cell model used in this calculation is a relatively small battery, the larger the cell size, the smaller the ratio of the volume occupied by the tab bending and welding parts to the cell volume, and the higher the volumetric energy density is.

[0115] Furthermore, the calculation results for the aluminum-plastic film and metal casings are summarized in Table 3. As can be seen from the table, the capacity gain of the metal casing is significantly greater than that of the aluminum-plastic film casing, and the capacity gain of the two-tab structure is significantly greater than that of the three-tab structure. Therefore, this utility model prefers to use a metal casing with a two-tab structure to manufacture the battery, aiming to obtain the maximum capacity improvement.

[0116] Table 3

[0117] Capacity benefits bipolar structure Triple ear structure Aluminum-plastic film casing 1.84％ 0.9％ metal casing 2.06％ 1.5％

[0118] This utility model also provides a battery, including the aforementioned housing 9, with a wound bare battery cell installed inside the housing 9.

[0119] The battery casing structure provided by this utility model has an open end on the large surface of the casing, allowing the stacked cores to be easily installed into the casing without damage. This eliminates the problem of electrode deformation or damage caused by excessive distance or uneven insertion force during installation. Therefore, when the stacked cores are placed inside the casing, they can be firmly abutted against the casing from all sides, maximizing battery capacity and significantly improving battery capacity and capacity density. The upper and lower casings are integrated, saving on upper casing handling and positioning equipment, simplifying the manufacturing process, and effectively avoiding positioning and handling errors. During welding, the integrated structure of the upper and lower casings also enhances welding reliability and reduces battery manufacturing costs.

[0120] It should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A laminated battery cell, characterized in that: It includes alternatingly stacked electrodes and diaphragms that are composited by hot pressing, with adjacent electrodes having opposite polarities and separated by the diaphragm. Each electrode has two grooves on one side, with an electrode tab extending from each of the two adjacent electrodes in each groove. The outside of each electrode tab is welded to a transition electrode tab. The diaphragm is cut at the edge of each groove and then placed in the corresponding groove after being bent along with the corresponding electrode tab.

2. The laminated battery cell according to claim 1, characterized in that: The electrode includes a positive electrode and a negative electrode. The positive electrode has a first positive groove and a second positive groove of the same size on one side, and a positive electrode tab extends from the first positive groove.

3. A laminated battery cell according to claim 2, characterized in that: The width of the positive electrode tab is X1, and the width of the first groove of the positive electrode is X2. X1 and X2 satisfy the relationship: 0.2mm≤(X2-X1) / 2≤0.5mm.

4. A laminated battery cell according to claim 2, characterized in that: The negative electrode plate has a first negative electrode groove and a second negative electrode groove of the same size on one side, and a negative electrode tab extends from the first negative electrode groove. The depth of the first negative electrode groove is less than or equal to the depth of the first positive electrode groove.

5. A laminated battery cell according to claim 4, characterized in that: The width of the first groove of the negative electrode is X5, the width of the negative electrode tab is X4, and the size of the negative electrode sheet covering the positive electrode sheet is r1. Then X4 and X5 satisfy the relationship: 0.2mm≤(X5-X4+2*r1) / 2≤0.5mm.

6. A laminated battery cell according to claim 4, characterized in that: The distance between the diaphragm cutting position and the inner wall of the second groove of the negative electrode is X7, where 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the second groove of the negative electrode, X4 is the width of the adapter tab, and the cutting height of the diaphragm cutting position is less than or equal to the distance to the root of the second groove of the negative electrode.

7. A laminated battery cell according to claim 4, characterized in that: There is a gap between the diaphragm cutting position and the negative electrode sheet, and the covering size of the diaphragm and the negative electrode sheet is r2, where r2≥0.1mm.

8. A battery comprising the laminated cell according to any one of claims 1 to 7, characterized in that: The stacked cells are located inside the casing.

9. A battery according to claim 8, characterized in that: The housing comprises an integral upper shell and a lower shell. The upper shell is a rectangular plate, and the lower shell is a rectangular shell. The included angle between the two ranges from 45° to 270°. The upper shell and the lower shell are sealed together after being pressed together.

10. A battery according to claim 8, characterized in that: A bending groove is formed at the junction of the upper and lower shells. The depth C1 of the bending groove and the thickness K of the shell satisfy the following relationship: 0.3≤C1 / K≤0.7.

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