Battery and manufacturing method thereof

Abstract

The invention discloses a battery and a manufacturing method thereof.The battery comprises a shell and a laminated cell arranged in the shell, the shell comprises an upper shell and a lower shell which are of an integrated structure, the laminated cell comprises pole pieces and diaphragms which are alternately stacked and compounded through hot pressing, and every two adjacent pole pieces are opposite in polarity and separated by the corresponding diaphragm; two grooves are formed in one side of each pole piece, a pole lug extends from each two adjacent pole pieces in each groove, the outer part of each pole lug is welded with a switching pole lug, and the diaphragm is cut at the edge of each groove and then is bent along with the corresponding pole lug and then is arranged in the corresponding groove. And the groove is also used for accommodating part of the transfer tab. According to the stacked core, the tabs are bent and welded to be hidden in the grooves, so that the head space utilization rate is high, the battery energy density is improved, the battery using performance is improved, meanwhile, the head space of the lithium battery is supported by the hardness of the battery core body, the service life of the battery is prolonged, and the safety performance of the battery is improved.

Description

Technical Field

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

[0002] A lithium battery includes a stacked core and a shell. The stacked core requires pre-welding the soft tabs, then transferring them to a hard tab with a slightly higher hardness, and then placing the bent soft tabs and hard tabs in the head space of the lithium battery near the tab side. Finally, the hard tabs are connected to the shell. When the power transmission end of the power-consuming device is connected to the positive and negative poles of the lithium battery shell, the lithium battery can provide power to the power-consuming device. However, the battery obtained under this manufacturing method has the following shortcomings: (1) The head space utilization rate is low, which will result in a large loss of energy density and affect its performance. (2) In some application scenarios, the head space of the lithium battery is not supported by the hardness of the battery body. When it is inevitably subjected to external forces, the vibration caused may cause the tabs to break, making the lithium battery power supply ineffective, and even causing the risk of internal short circuit.

[0003] Conventional hard-shell batteries are first fabricated from stainless steel sheets or other materials into an upper cover and lower chamber. The battery cells are then placed into the lower chamber, and after the upper and lower chambers are positioned, the upper cover is pressed onto the lower chamber. Finally, a seal is formed by laser welding. During the welding process, positioning and handling errors can easily cause the upper and lower chambers to shift during assembly, impacting weld reliability and product yield. Furthermore, this structure is expensive to manufacture. Summary of the Invention

[0004] In response to the problems in the prior art, the present invention discloses a laminated battery cell and a battery. The present invention hides the bending and welding of the tabs in the grooves, thereby increasing the utilization rate of the head space, improving the battery energy density, and enhancing the battery performance. At the same time, the head space of the lithium battery is supported by the hardness of the battery cell body, and the risk resistance of the tabs is greatly improved, thereby improving the service life and safety performance of the battery.

[0005] The present invention first provides a battery, including a shell and a laminated battery cell arranged inside the shell, the shell including an upper shell and a lower shell of an integral structure, the laminated battery cell including pole pieces and diaphragms that are alternately stacked and composited by hot pressing, and the two adjacent pole pieces have opposite polarities and are separated by a diaphragm, and two grooves are provided on one side of each pole piece, and a pole ear extends from each of the two adjacent pole pieces in each groove, and the outside of each pole ear is welded to a transfer pole ear, and the diaphragm is cut at the edge of each groove and used to be bent along with the corresponding pole ear and placed in the corresponding groove, and the groove is also used to accommodate part of the transfer pole ear.

[0006] As a further solution, the upper shell is a rectangular plate, the lower shell is a rectangular shell, and the angle between the two is in the range of 45°-270°. The upper shell and the lower shell are sealed after being pressed together.

[0007] As a further solution, the electrode sheet includes a positive electrode sheet and at least one negative electrode sheet, or includes at least one positive electrode sheet and one negative electrode sheet.

[0008] As a further solution, a bending groove is formed at the junction of the upper shell and the lower shell, and the depth C1 of the bending groove and the thickness K of the shell satisfy the relationship: 0.3≤C1 / K≤0.7.

[0009] As a further solution, the distance between the diaphragm cutting position and the inner wall of the groove is X7, where 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the groove, X4 is the width of the transfer tab, and the cutting height of the diaphragm cutting position is less than or equal to the distance from the cutting to the root of the groove.

[0010] As a further solution, a gap is provided between the cutting position of the diaphragm and the pole piece, and the covering size of the diaphragm and the pole piece is r2, r2 ≥ 0.1 mm.

[0011] As a further solution, the method for bending the tab is: first bend the tab and the diaphragm together into a fold, then bend the tab and the transfer tab together along the opposite direction of the fold, and then lead out the transfer tab.

[0012] The present invention also provides a method for manufacturing a battery, which is used to manufacture the battery, comprising the following steps:

[0013] Making laminated battery cells;

[0014] Making the shell;

[0015] Connect the positive electrode tab of the laminated cell to the pole of the shell, and the negative electrode tab to the shell;

[0016] After placing the laminated battery cells into the lower shell, the upper shell is flipped over and pressed onto the lower shell, and the three edges of the shell are laser welded to form a seal.

[0017] As a further solution, the method for making a laminated battery cell includes:

[0018] S1. Make positive and negative electrodes with tabs respectively.

[0019] S2, alternately stacking the positive electrode sheets, the negative electrode sheets and the separator and then performing hot pressing to form a stacked core;

[0020] S3, cutting the diaphragm, and pre-welding the positive and negative electrode tabs of the prepared stacked core against the edge of the diaphragm so that each layer of electrode sheets is connected through the tabs;

[0021] S4, connecting each electrode layer on the stacked core to a transfer tab;

[0022] S5. Bend the tab along the root of the diaphragm cutting position and insert it into the corresponding groove after bending.

[0023] As a further solution, the method for making the shell is:

[0024] X1. First, stamp the shell into an integrated structure;

[0025] X2. Determine the thickness of the shell as K, calculate the depth C1 of the bending groove 95, set the groove width K1 ≥ 2K, process the bending groove along the center line of the shell, and verify the position of the folding axis K1 / 2.

[0026] The characteristics and beneficial effects of the present invention are:

[0027] The battery:

[0028] (1) The laminated battery cell described in the present invention hides the bending and welding of the tabs in the grooves. The head space of the lithium battery is supported by the hardness of the battery cell body, and the risk resistance of the tabs is greatly improved, thereby improving the service life and safety performance of the battery.

[0029] (2) The laminated battery cell structure provided by the present invention enables high head space utilization, increases battery energy density, and improves battery performance.

[0030] (3) The present invention forms a stacked core by hot pressing, that is, by pre-heating the diaphragm and the electrode to completely eliminate the hidden dangers of diaphragm wrinkles and electrode powder falling, while ensuring that the internal structure of the battery is completely stable, which can better improve the product yield.

[0031] (4) The battery of the present invention adopts an integrated structure, eliminating the need for positioning the upper cover plate and the lower accommodating cavity, as well as the need for transporting the upper cover plate. This can avoid the influence of positioning errors of the upper cover plate and the lower accommodating cavity and the need for transporting the upper cover plate on the combined welding, and can effectively solve the offset problem during combined welding of the upper cover plate and the lower accommodating cavity, thereby ensuring welding reliability and product yield, while reducing the manufacturing cost of hard-shell batteries.

[0032] (5) When the stacked core of the present invention is placed inside the shell, the four sides can abut against the inside of the shell, which can maximize the battery capacity and greatly improve the battery capacity and capacity density. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 Schematic diagram of the positive electrode structure according to an embodiment of the present invention;

[0035] Figure 2 for Figure 1 AA sectional view;

[0036] Figure 3 Schematic diagram of the negative electrode sheet according to an embodiment of the present invention;

[0037] Figure 4 Based Figure 3 BB cross-sectional view;

[0038] Figure 5 Schematic diagram of the manufacturing process of the electrode according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic structural diagram of a Z-stacked single-sided positive electrode finishing structure according to an embodiment of the present invention;

[0040] Figure 7 This is a schematic structural diagram of a Z-stacked single-sided negative electrode finishing structure according to an embodiment of the present invention;

[0041] Figure 8 This is a schematic structural diagram of a thermal composite laminate according to an embodiment of the present invention;

[0042] Figure 9 This is a schematic diagram of a laminated battery cell before being bent according to an embodiment of the present invention;

[0043] Figure 10 This is a schematic diagram of tab pre-welding according to an embodiment of the present invention;

[0044] Figure 11 A schematic diagram of tab cutting according to an embodiment of the present invention;

[0045] Figure 12 This is a schematic diagram of a laminated battery cell after bending according to an embodiment of the present invention;

[0046] Figure 13 for Figure 12 CC sectional view;

[0047] Figure 14 for Figure 13 Enlarged view of the middle X section;

[0048] Figure 15 Schematic diagram of the transfer tab structure according to an embodiment of the present invention;

[0049] Figure 16 is a schematic diagram of a housing according to an embodiment of the present invention;

[0050] Figure 17A side view of a housing according to an embodiment of the present invention;

[0051] Figure 18 A schematic diagram of a bending groove according to an embodiment of the present invention;

[0052] Figure 19 This is a flow chart of a method for manufacturing a housing according to an embodiment of the present invention;

[0053] Figure 20 This is a box plot of energy density of Example 1 of the present invention;

[0054] Figure 21 This is a box plot of energy density of Example 2 of the present invention;

[0055] Figure 22 This is a box plot of energy density of Example 3 of the present invention;

[0056] Figure 23 This is a box plot of energy density of Example 4 of the present invention;

[0057] Figure 24 is a cross-sectional view of a battery according to an embodiment of the present invention;

[0058] Figure 25 for Figure 24 Enlarged view of the middle Y part.

[0059] Description of reference numerals:

[0060] 1-positive electrode sheet; 11-positive electrode first groove; 12-positive electrode second groove; 13-positive electrode tab; 14-positive electrode active material; 15-positive electrode foil; 2-negative electrode sheet; 21-negative electrode first groove; 22-negative electrode second groove; 23-negative electrode tab; 24-negative electrode foil; 25-negative electrode active material; 3-diaphragm; 4-welding position; 5-single-sided positive electrode sheet; 6-single-sided negative electrode sheet; 7-transfer tab; 8-tab glue; 9-shell; 91-upper shell; 92-lower shell; 93-pole; 94-liquid 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 DESCRIPTION

[0061] In order to facilitate understanding of the present invention, the present invention will be described in more detail below, and embodiments of the present invention are given, but the scope of the present invention is not limited thereby.

[0062] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0063] In existing laminated battery cells, when the tabs and adapter tabs are welded and bent and then placed in the shell, they occupy a large space in the shell, resulting in a smaller volume of laminated batteries installed inside a shell of the same volume, thereby reducing the energy density of the battery. In addition, since the bending portion is arranged in the head area of ​​the shell beyond the end face of the battery cell pole head, there are no other supports in this area except the tab bending portion. When this part of the shell is subjected to mechanical abuse conditions such as rolling or falling, or is hit by external forces, it is easily affected by the impact force, causing the tab to break, and then causing the battery cell to fail, because it has no support. In order to maximize the energy density of the battery cell, using the tab bending method to reduce the space occupied by the tab is already a common method in the industry. However, we have verified through a large number of tests how to bend the tab and reduce the space occupied by the tab bending portion, while increasing the overall energy density of the battery. In addition, the battery not only includes a core but also a shell. The existing shells are all split structures. After the core is placed in the shell, it needs to be connected to the shell through the tabs, so there are requirements for the installation position and size of the core. In order to maximize the use of the shell space, the core size is generally set large enough, which increases the difficulty of placing the core into the shell. When the existing core is placed in the shell, an external limiting mechanism is generally required to limit the shell and the core, and then the core is placed in the shell, and then the upper cover and the lower accommodating 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 and the lower accommodating cavity are welded in a circumferential direction, the machine avoidance problem also needs to be considered. Therefore, the entire assembly line requires a lot of supporting equipment and the precision requirements are very high. In order to solve the above problems, the present application proposes a battery structure, including improvements to the laminated battery cells and the shell.

[0064] A laminated battery cell, such as Figures 1 to 15 As shown, it includes alternately stacked pole pieces and a diaphragm 3 that are laminated by hot pressing. Adjacent pole pieces have opposite polarities and are separated by the diaphragm 3. Two grooves are provided on one side of the pole piece. A tab extends from each of the two adjacent pole pieces. Each tab is welded to a transfer tab 7. The diaphragm 3 is cut at the edge of each groove and bent along the corresponding tab before being placed in the corresponding groove. The distance between the two grooves is greater than 1 mm.

[0065] The laminated cell structure provided by this invention maximizes headroom utilization, increases battery energy density, and enhances battery performance. By concealing the tab bending and welding within the groove, the headroom of the lithium battery is supported by the rigidity of the cell body, significantly improving the tab's risk resistance and extending the battery's lifespan and safety.

[0066] The positive electrode foil 15 is coated with positive electrode active material 14 on both sides to form the positive electrode sheet 1. Since the improvement of this application is only a structural improvement, the foil and active material are both made of existing technology, such as aluminum foil and lithium nickel cobalt manganese oxide.

[0067] A positive electrode first groove 11 and a positive electrode second groove 12 are provided on one side of the positive electrode sheet 1, and a positive electrode tab 13 extends from the positive electrode first groove 11. In the height direction, the positive electrode tab 13 is composed of two parts. The first part of the positive electrode tab is in the positive electrode first groove 11, and its height is Y1. The second part of the positive electrode tab extends out of the positive electrode first groove 12 along the height direction, and its height is Y2. The total height of the positive electrode tab is Y1+Y2. Figure 1 As shown: in the width direction, the width of the positive electrode tab 13 is X1, and the width of the positive electrode first 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 no positive electrode active material 14 remains on the prepared 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 break when bent in the subsequent bending process. Methods for removing active materials include but are not limited to laser cleaning, scraping with a blade, or solvent removal. The current minimum theoretical removal accuracy in the industry is 0.1mm. After repeated tests, when this data is greater than or equal to 0.2mm, the process capability can be fully guaranteed and manufacturing is convenient. If (X2-X1) / 2 is too large, too much active material will be lost, which will reduce the capacity of the electrode. 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 size of the first positive electrode groove is the same as the size of the second positive electrode groove.

[0068] The negative electrode foil 25 is coated with negative electrode active material 24 on both sides to form the positive electrode sheet 2. Since the improvement of this application is only a structural improvement, the foil and active material are both based on existing technologies, such as copper foil and lithium titanate.

[0069] A negative electrode first groove 21 and a negative electrode second groove 22 are provided on one side of the negative electrode sheet 2, and a negative electrode tab 23 extends from the negative electrode first groove 21. The structural diagram of the negative electrode sheet 2 is shown in FIG. Figure 2As 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 consistent. The width of the negative electrode first 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 remaining on the prepared negative electrode tab 23. Otherwise, because the negative electrode active material is more brittle than the foil, the negative electrode tab will be difficult to bend or will break when bent in 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 is too small, which will reduce the capacity of the electrode sheet.

[0070] The width of the negative electrode second groove 21 is X6, and X6 and X5 satisfy the relationship: X6-X5=0. In the height direction, the negative electrode tab 23 is composed of two parts. The first part of the negative electrode tab is within the negative electrode first groove 21 and has a height of Y4. The second part of the negative electrode tab extends out of the negative electrode first groove 21 along the height direction and has a height of Y5. The total height of the negative electrode tab 23 is Y4+Y5. The height of the negative electrode second 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-welding area. After the tab is subsequently bent, its height cannot be greater than the thickness H1 of the battery body, 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 pole ear is smaller than the distance between the root of the positive electrode groove and the root of the pole ear, and the specific smaller dimension is r1; in the height direction, the depth of the negative electrode groove is smaller than that of the positive electrode groove, and the specific smaller dimension is r1. Such a design can meet the dimensions of the positive and negative electrode sheet coatings.

[0071] The present invention provides a method for manufacturing a laminated battery core (hereinafter referred to as a "laminated core"), comprising the following steps:

[0072] S1. Make the positive and negative electrodes. The specific method is as follows:

[0073] like Figure 5 As shown, the manufacturing methods of the positive and negative electrodes are the same. The positive electrode is used as an example for explanation. The specific method is as follows:

[0074] S11, die-cutting the positive electrode sheet 1 coated with the positive electrode active material 15 on the foil 14 into a designed shape using a metal mold, and the die-cut positive electrode sheet 1 is provided with a positive electrode tab 13;

[0075] S12, removing the positive electrode active material 15 near the positive electrode tab 13 to expose the foil 14 in the removal area A, thereby producing an empty tab foil area;

[0076] S13 , along the extension direction of the positive electrode tab 13 , retain the integrity of the positive electrode tab 13 and cut off both sides thereof. At this time, the length of the positive electrode tab 13 becomes longer.

[0077] S14 , using a metal mold or laser die-cutting method, the positive electrode sheet 1 is cut away from the portion where it fits with the negative electrode tab 23 to form a positive electrode second groove 12 .

[0078] S2, alternately stacking the positive electrode sheet 1, the negative electrode sheet 2 and the separator 3 and then hot pressing and compounding them to form a laminated battery cell,

[0079] The specific methods of hot pressing composite include three types:

[0080] The first method uses a Z-stack method: a movable stacking table pulls the separator 3 in a Z-shaped reciprocating motion, alternating the positive and negative electrode sheets 1 and 2 to complete the stacking process. The separator 3 tension is dynamically adjusted (5-15N), and the robot positioning accuracy is ≤ 0.3mm, forming a "positive electrode sheet - separator - negative electrode sheet - separator" cycle.

[0081] The second method is to use a cutting and stacking integrated method, which means that the cutting and stacking integrated machine integrates three types of machines: electrode die cutting / laser cutting, Z-shaped stacking machine, and glue laminating and hot pressing machine. The cutting and stacking integrated machine retracts and releases the positive and negative electrode sheets and diaphragms at the same time, and folds them in a Z shape under the action of the main stacking table or the swing arm. When the number of sheets is stacked to the set number, the diaphragm is cut and glued, and then hot pressed into a stacked battery cell. The schematic diagram of the Z stacking structure of the above two methods is shown as follows Figure 6-Figure 7 As shown, the laminated battery cell can be terminated on one side of the negative electrode or on one side of the positive electrode.

[0082] like Figure 8 As shown, the third method involves first thermally laminating the positive or negative electrode sheet with the separator and then stacking them in a certain order. This method forms a core stack through hot pressing. This method completely eliminates the potential risks of separator wrinkles and electrode powder shedding by thermally laminating the separator and electrode sheets in advance. It also ensures a completely stable internal battery structure, significantly improving product yield.

[0083] S3. Pre-weld the positive electrode tab 13 and the negative electrode tab 23 of the prepared stacked core against the edge of the diaphragm 3 so that each layer of electrode sheets is connected through the tabs.

[0084] S31, pre-weld and cut the positive electrode tab 13 and the negative electrode tab 23. The pre-welding direction is along the extension direction of the tab. The edge of the weld mark close to the electrode side is connected to the edge of the diaphragm 3. The total thickness of the stacked core body is H1. The pre-welding height Y8 should meet the requirement of Y8≤H1. Then, cut off the remaining tabs. Figure 9 and Figure 10 shown.

[0085] S32. Since this solution includes the positive electrode tab 13 and the negative electrode tab 23, the bending corresponds to the positive electrode tab bending position B and the negative electrode tab bending position C. The bending methods of the two are the same. For the convenience of description, the negative electrode sheet is used as an example for description.

[0086] In order to place the negative electrode tab 23 at the negative electrode tab bending position C after being bent, the separator 3 at the negative electrode tab bending position C needs to be cut first.

[0087] The distance between the diaphragm cutting position and the inner wall of the negative electrode second groove 21 is X7. X7 needs to meet the design value of the coating of the diaphragm 3 and the negative electrode sheet 2. It is generally taken as 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the negative electrode second groove 21, X4 is the width of the transfer tab 7, and the cutting height of the diaphragm cutting position is Y7. Y7≤Y4+r2, Y4+r2 is the distance from the maximum cutting height of the diaphragm to the root of the groove. If it is greater than this value, the size of the diaphragm coating the negative electrode will be smaller, reducing the safety of the battery cell. If it exceeds Y4, it will cut 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, that is, Y5≤Y7≤H1.

[0088] There is a gap between the diaphragm cutting position and the negative electrode sheet 2. The covering size of the diaphragm 3 and the negative electrode sheet 2 is r2, r2 ≥ 0.1mm. On the one hand, it meets the processing accuracy, and on the other hand, it prevents the negative electrode and the positive electrode from short-circuiting and catching fire after the diaphragm 3 shrinks due to heat. The schematic diagram of the stacked core formed by the above method is as follows Figure 12 The slots formed by the positive electrode first groove 11 and the negative electrode second groove 21 are collectively referred to as first grooves F, and the slots formed by the negative electrode first groove 22 and the positive electrode second groove 12 are collectively referred to as second grooves G.

[0089] S4. Pre-weld each electrode layer on the stacked core and connect it to a transfer tab 7. Preferably, the positive transfer tab is made of aluminum and the negative transfer tab is made of nickel-plated copper. The transfer tab should be made of a metal material similar to the stacked core material to reduce the potential difference between the positive and negative electrodes.

[0090] The transition tab 7 is an aluminum tab or nickel tab with a tab glue 8 that is slightly harder than the positive or negative electrode foil. One end of the transition tab 7 is a welding position, which is connected to the tab of the stacked core by ultrasonic welding or laser welding, so that each layer of the stacked core is connected to the transition tab. In the thickness direction projection, the projection of the pre-welded tab of the stacked core can completely cover the projection of the welding position of the transition tab 7, ensuring that the stacked core tab has sufficient material to connect with the transition tab and ensuring a sufficiently large overcurrent density. At the same time, since the current passes through the tab during the heavy discharge process, the heat at the tab is significantly concentrated. A sufficiently large welding area can alleviate the heat concentration and reduce the possibility of thermal failure of the battery. That is, the height of the welding position of the transition tab 7 is Y10, and Y10, Y8 and H1 satisfy the relationship: Y10≤Y8≤H1. The width of the tab glue is X9. When the adapter tab 7 is connected to the positive electrode sheet 1, X9 and X2 or X3 satisfy the 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 sheet 2, X9 and X5 or X6 satisfy the relationship: 0≤(X9-X5) / 2≤0.5mm or 0≤(X9-X6) / 2≤0.5mm.

[0091] For ease of understanding, the details are described using the adapter tab 7 and the positive electrode tab 13 as an example. After connecting the adapter tab 7 and the positive electrode tab 13, they are bent along the base of the separator cutout and inserted into the first groove F. A portion of the tab glue 8 is also inserted into the first groove F, and the ratio of the inserted portion Y91 to the exposed portion Y92 satisfies the relationship: 0 ≤ Y91 / Y92 ≤ 0.3. If Y91 / Y92 is less than 0, the tab glue will be exposed too much after the stack is placed in the housing and top-sealed, occupying a large space and not conducive to improving battery energy density. If Y91 / Y92 is greater than 0.3, that is, more tab glue is inserted into the first groove than is used for the top seal, the height of the first groove will increase, reducing battery energy density, and the reliability of the top seal will be compromised. The bending process requires two folds: one fold and then a second fold. The positive electrode tab 13 and the diaphragm 3 are bent together in the first fold, and the positive electrode tab 13 and the transfer tab 7 are bent together in the opposite direction of the first fold. Then, the transfer tab 7 is bent away from the core stack at a set angle and then led out. The range of the set angle is <180°. The height Y7 of the first groove G is composed of the height Y91 of the tab glue 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 = the thickness of the positive electrode foil * the number of positive electrode sheet layers + the thickness of the diaphragm * the number of diaphragm layers; the height of the second fold = the thickness of the positive electrode foil * the number of positive electrode sheet layers + the thickness of the transfer tab. Therefore, the total height of the first groove Y7 = Y91 + the thickness of the positive electrode foil * the number of positive electrode sheet layers * 2 + the thickness of the diaphragm * the number of diaphragm layers + the thickness of the transfer tab. The bending method of the negative electrode sheet is the same as that of the positive electrode, and will not be repeated here.

[0092] The present invention provides a battery, such as Figures 16 to 25As shown, the battery cell comprises the laminated cell and a housing 9 disposed externally thereto. The housing 9 comprises an upper housing 91 and a lower housing 92 of an integral structure. The upper housing 91 is a rectangular plate, and the lower housing 92 is a rectangular shell. The angle between the upper housing 91 and the lower housing 92 is in the range of 45°-270°. The upper housing 91 and the lower housing 92 are sealed together after being pressed together. Compared to conventional hard-shell battery structures, the battery structure provided by the present invention eliminates the need to position the upper cover plate and the lower accommodating cavity, as well as the need to transport the upper cover plate. This avoids the effects of positioning errors of the upper cover plate and the lower accommodating cavity, as well as the effects of transport errors of the upper cover plate on the combined welding process. This effectively solves the problem of offset during the combined welding of the upper cover plate and the lower accommodating cavity, ensures welding reliability and product yield, and reduces the manufacturing cost of hard-shell batteries.

[0093] In one embodiment, a pole 93 and a liquid injection hole 94 are provided on any surface of the lower shell 92 except the surface with the largest area. Preferably, the pole 93 and the lower shell 92 are welded.

[0094] 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 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, and it is difficult to bend, resulting in difficulty in operation, inconsistent angles, and poor consistency of the processed products. If C1 / K>0.7, there is too little remaining material at the connection, the connection strength is insufficient, and fatigue cracks are easily generated during repeated folding. The preferred range of C1 / K is 0.4~0.6, which can well balance the foldability and strength. Example: If the shell thickness K=2mm, then C1=0.8~1.2mm. In the width direction, the width of the bending groove 95 is K1, and the groove is symmetrically arranged along the outer wall of the shell, and K1 ≥ 2K, to ensure stress dispersion during processing. If K1 is too small, it will cause stress concentration during processing, reduce the fatigue strength of the material, and increase the risk of cracks. When folding, it is carried out along K1 / 2 of the bending groove, that is, along the outer wall of the lower accommodating cavity, that is, the center line of the bending groove coincides with the outer wall of the shell, which ensures that the upper cover and the lower accommodating cavity are aligned during folding and the operation is smooth. The upper cover rotates around the outer wall of the lower accommodating cavity (K / 2 axis) to achieve precise and controllable opening and closing trajectory.

[0095] The assembly method of the housing 9 and the laminated core is as follows:

[0096] Step 1: First, the shell is stamped into an integrated structure, and the angle V between the upper shell 91 and the lower shell 92 is 45-270 degrees;

[0097] Step 2: Process a bending groove 95 at the junction of the upper shell 91 and the lower shell 92 to facilitate folding. The specific process is: 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, process the bending groove along the center line of the shell, verify the position of the folding axis K1 / 2, and perform multiple folding tests.

[0098] Step 3: Connect the positive electrode tab 13 of the laminated battery cell to the pole 93 of the shell, and connect the negative electrode tab 23 to the shell 9.

[0099] Step 4: Place the laminated battery cell into the lower shell 92 , and flip the upper shell 91 over and press it onto the lower shell 92 .

[0100] Step 6: Create a seal by laser welding the three edges of the shell.

[0101] The shell can be made of conductive metal materials such as aluminum, steel, stainless steel, nickel, copper or magnesium alloy, and can also be made of aluminum-plastic film.

[0102] Comparative Example 1

[0103] The shell 9 is an aluminum-plastic film shell. The calculation is performed using the battery cell model 566875 (total battery cell thickness 5.6 mm, width 68 mm, height 75 mm). The calculated average battery cell energy density is 784.98 Wh / L.

[0104] Example 1

[0105] The shell 9 is an aluminum-plastic film shell, and the laminated battery core has a two-pole ear structure (one positive pole ear and one negative pole ear). The ear glue is inserted into the groove 1.6mm, that is, Y91 = 1.6mm. The calculated average energy density of the battery core is 799.42Wh / L, and the battery capacity can be increased by 1.84%. The capacity data before and after the experiment are shown in Table 1 below. Therefore, the structure of the present invention can completely improve the capacity of the battery with a two-pole ear structure. The box plot is as follows Figure 20 shown.

[0106] Example 2

[0107] The shell 9 is an aluminum-plastic film shell, and the laminated battery cell has a three-pole ear structure (one positive electrode ear and two negative electrode ears or one negative electrode ear and two positive electrode ears), wherein the ear glue is plugged into the groove 1.6mm, that is, Y91 = 1.6mm. The calculated average energy density of the battery cell is 791.15Wh / L, and the battery capacity can be increased by 0.9%. Therefore, the structure of the present invention can completely improve the battery capacity of the two-pole ear structure, and the box-line diagram is shown in the figure. Therefore, the structure of the present invention can completely improve the battery capacity of the three-pole ear structure, and the box-line diagram is shown in the figure. Figure 21 shown.

[0108] Table 1

[0109]

[0110]

[0111]

[0112] Because the battery cell model used in this calculation is a smaller battery, the larger the battery model, the higher the capacity improvement achieved by the present invention. In summary, the structure of the present invention can increase battery capacity. Based on the calculated data of the two-pole lug structure and the three-pole lug structure, the two-pole lug structure achieves a greater capacity gain and is less difficult to process than the three-pole lug structure. Therefore, the present invention prefers the two-pole lug structure.

[0113] Comparative Example 2

[0114] The casing is made of stainless steel or other metal materials, and the tabs of the stacked cores are welded directly to the casing. Calculations were performed using cell model 566875 (total cell thickness 5.6mm, width 68mm, height 75mm). The average energy density was 785.62Wh / L.

[0115] Example 3

[0116] The shell material is the same as that of comparative example 2, and the tabs of the stacked core are directly welded to the shell. The laminated battery cell has a three-tab structure (one positive tab and two negative tabs or one negative tab and two positive tabs), and the battery cell model 566875 (total thickness of the battery cell is 5.6mm, width is 68mm, and height is 75mm) is used for calculation, wherein the tab glue is plugged into the groove 1.6mm, that is, Y91=1.6mm. The calculated average energy density of the battery cell is 801.84Wh / L, and the battery capacity can be increased by 2.06%. Therefore, the structure of the present invention can completely improve the capacity of the battery with a two-tab structure, as shown in the box diagram. Figure 22 shown.

[0117] Example 4

[0118] The shell material is the same as that of comparative example 2, and the tabs of the stacked core are directly welded to the shell. The stacked core battery cell has a two-pole tab structure (one positive tab and one negative tab), and the battery cell model 566875 (total thickness of the battery cell is 5.6mm, width is 68mm, and height is 75mm) is used for calculation, wherein the tab glue is plugged into the groove 1.6mm, that is, Y91=1.6mm. The calculated average energy density of the battery cell is 794.84Wh / L, and the battery capacity can be increased by 1.5%. Therefore, the structure of the present invention can completely improve the capacity of the three-pole tab structure battery, as shown in the box line diagram. Figure 23 shown.

[0119] The data of Example 3 and Example 4 are shown in Table 2.

[0120] Table 2

[0121]

[0122]

[0123] As mentioned above, the structure of the present invention can increase battery capacity. Based on the calculated data for both two- and three-tab structures, the two-tab structure achieves greater capacity gains and is less difficult to process than the three-tab structure, making the two-tab structure preferred in the present invention. Because the battery cell model used in this calculation is a smaller battery, the larger the cell size, the smaller the ratio of the volume of the bent tab and its welded portion to the cell volume, and the higher the improved volumetric energy density.

[0124] In addition, the calculation results of the shells of aluminum-plastic film and metal are summarized in Table 3. From the table, it can be seen that the capacity gain of the metal shell is significantly greater than that of the aluminum-plastic film shell, and the capacity gain of the two-pole lug structure is significantly greater than that of the three-pole lug structure. Therefore, the present invention preferably uses a metal shell with a two-pole lug structure to manufacture the battery, aiming to obtain the maximum capacity improvement.

[0125] Table 3

[0126] Capacity gains Two-pole ear structure Three-pole structure Aluminum-plastic film shell 1.84％ 0.9％ Metal shell 2.06％ 1.5％

[0127] The present invention further provides a battery, comprising the above-mentioned shell 9 , wherein a wound bare cell is installed inside the shell 9 .

[0128] The battery shell structure provided by the present invention has an open end on the large surface of the shell, allowing the stacked core to be easily installed in the shell without being damaged. There is no problem of pole piece deformation or damage caused by excessive distance or uneven insertion force when inserting into the shell. Therefore, when the stacked core is placed inside the shell, it can abut against the inside of the shell on all sides, which can maximize the battery capacity design and greatly improve the battery capacity and capacity density. The upper and lower shells are an integrated structure, eliminating the need for upper shell handling equipment and upper and lower shell positioning equipment. The processing technology is simple and effectively avoids positioning errors and handling errors. During welding, the upper and lower shells are an integrated structure, which also enhances welding reliability and reduces the manufacturing cost of the battery.

[0129] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A battery, characterized in that: It includes a shell and a laminated battery cell arranged inside it, the shell includes an upper shell and a lower shell of an integral structure, the laminated battery cell includes pole pieces and diaphragms that are alternately stacked and composited by hot pressing, and the two adjacent pole pieces have opposite polarities and are separated by a diaphragm, and two grooves are provided on one side of each pole piece, one of which has a pole ear extending from the pole piece, and the positions of the grooves where the two adjacent pole ears are located do not overlap, and the outside of each pole ear is welded to a transfer pole ear, and the diaphragm is cut at the edge of each groove and used to be bent along with the corresponding pole ear and placed in the corresponding groove, and the groove is also used to accommodate part of the transfer pole ear.

2. A battery according to claim 1, characterized in that: The upper shell is a rectangular plate, the lower shell is a rectangular shell, and the angle between the two is in the range of 45°-270°. The upper shell and the lower shell are sealed after being pressed together.

3. A battery according to claim 1, characterized in that: The electrode sheet includes a positive electrode sheet and at least one negative electrode sheet, or includes at least one positive electrode sheet and one negative electrode sheet.

4. The laminated battery cell according to claim 1, characterized in that: A bending groove is formed at the junction of the upper shell and the lower shell, and the depth C1 of the bending groove and the thickness K of the shell satisfy the relationship: 0.3≤C1 / K≤0.

7.

5. A battery according to claim 1, characterized in that: The distance between the diaphragm cutting position and the inner wall of the groove is X7, where 0.1≤X7≤(X6-X4) / 2, where X6 is the groove width of the groove, X4 is the width of the transfer tab, and the cutting height of the diaphragm cutting position is less than or equal to the distance from the cutting to the root of the groove.

6. A battery according to claim 1, characterized in that: There is a gap between the cutting position of the diaphragm and the pole piece, and the covering size of the diaphragm and the pole piece is r2, r2≥0.1mm.

7. A battery according to claim 1, characterized in that: The tab bending method is as follows: first, the tab and the diaphragm are bent together into a fold, then the tab and the transfer tab are bent together in the opposite direction of the fold, and then the transfer tab is bent away from the stacked core at a set angle and then led out, wherein the set angle range is <180°.

8. A method for manufacturing a battery, for manufacturing the battery according to any one of claims 1 to 7, characterized in that: The steps include: Making laminated battery cells; Making the shell; Connect the positive electrode tab of the laminated cell to the pole of the shell, and the negative electrode tab to the shell; After placing the laminated battery cells into the lower shell, the upper shell is flipped over and pressed onto the lower shell, and the three edges of the shell are laser welded to form a seal.

9. The method for manufacturing a battery according to claim 8, wherein: The method of making a laminated battery cell includes: S1. Make positive and negative electrodes with tabs respectively. S2, alternately stacking the positive electrode sheets, the negative electrode sheets and the separator and then performing hot pressing to form a stacked core; S3, cutting the diaphragm, and pre-welding the positive and negative electrode tabs of the prepared stacked core against the edge of the diaphragm so that each layer of electrode sheets is connected through the tabs; S4, connecting each electrode layer on the stacked core to a transfer tab; S5. Bend the tab along the root of the diaphragm cutting position and insert it into the corresponding groove after bending.

10. The method for manufacturing a battery according to claim 8, wherein: The method of making the shell is: X1. First, stamp the shell into an integrated structure; X2. Determine the thickness of the shell as K, calculate the depth C1 of the bending groove 95, set the groove width K1 ≥ 2K, process the bending groove along the center line of the shell, and verify the position of the folding axis K1 / 2.

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