Secondary battery, preparation method of secondary battery, energy storage battery pack and preparation method of energy storage battery pack

Abstract

The embodiment of the invention relates to the field of energy storage batteries, and provides a secondary battery and a preparation method thereof, and an energy storage battery pack and a preparation method thereof, and the preparation method comprises the following steps: forming a pole which comprises a body part with a first groove, an extension part, a protruding part located on the bottom surface of the first groove, and a groove located on the side surface of the body part; the top cover is assembled, the pole, the insulating layer, the bright aluminum sheet and the sealing ring are sequentially assembled according to the sequence, the sealing ring is clamped to the end of the pole, the inner side face of the sealing ring corresponds to the groove of the pole, and the top face of the sealing ring is opposite to the bottom face of part of the bright aluminum sheet; providing a winding battery cell, and carrying out second welding treatment on the tabs and the switching sheets; assembling the winding battery cell and the top cover, extruding the winding battery cell and the top cover to enable one end, far away from the extension part, of the pole to be positioned in the second groove of the switching piece, and filling the groove with the sealing ring; carrying out third welding treatment on the pole and the switching piece and forming a first welding layer; and assembling the shell and winding the battery core so as to improve the volume utilization rate of the secondary battery.

Description

Technical Field

[0001] The present application relates to the field of energy storage batteries, and in particular to a secondary battery and a preparation method thereof, an energy storage battery pack and a preparation method thereof. Background Art

[0002] Lithium-ion / sodium-ion batteries have become the core of energy storage due to their wide range of applications, such as electric vehicles, portable electronic devices and large-scale energy storage systems. This type of battery is mainly composed of core components such as positive electrode materials, negative electrode materials, diaphragms, electrolytes and shells. The packaging forms include square aluminum shells, square soft packs, cylindrical aluminum shells and cylindrical steel shells. Each form is designed for specific application scenarios, aiming to improve the battery's unit volume energy density, safety performance and cycle life.

[0003] Optimizing the battery structure is the key to improving space utilization. The assembly of the internal cells of square batteries usually adopts a winding or lamination process. The specific structure will directly determine the arrangement efficiency and space occupancy of the internal materials of the cell. The ear design, whether single-sided or double-sided, needs to ensure that the positive and negative electrodes can be effectively welded to the adapter or pole, thereby realizing the electrical connection between the cell and the external circuit. Current technological advances have improved the overall structural compactness and electrical connection efficiency of the battery to a certain extent by adjusting the pole configuration and the layout of the internal connecting plate, but the volume utilization of the cell structure still needs to be broken through.

[0004] On the basis of ensuring high performance and safety of the battery, further improving the space utilization of the battery cell, continuously optimizing the battery structure design, and enhancing the sealing performance and reliability are the current research and development focuses. In addition, with the growing market demand for electric vehicles and portable electronic devices, the performance requirements for batteries are becoming increasingly stringent. How to extend the cycle life and enhance safety while maintaining the battery volume has also become a focus in the field of battery technology. Summary of the invention

[0005] The embodiments of the present application provide a secondary battery and a method for preparing the same, an energy storage battery pack and a method for preparing the same, which are at least beneficial in reducing the height of the pole, thereby improving the volume utilization of the secondary battery.

[0006] According to some embodiments of the present application, on the one hand, the embodiments of the present application provide a method for preparing a secondary battery, including: forming a pole, the pole including: a main body, the main body having a first groove inside; an extension, the extension extending from the main body in a direction away from the first groove; a protrusion, the protrusion being located on a portion of the bottom surface of the first groove, the protrusion protruding toward the opening direction of the first groove; wherein the side of the main body away from the extension has a groove recessed toward the first groove; assembling a top cover, the pole passes through the insulating layer and the pole through hole of the bare aluminum sheet in sequence and extends to the other end of the bare aluminum sheet, the sealing ring engages the end of the pole, and the inner side surface of the sealing ring corresponds to the groove of the pole, the top surface of the sealing ring is opposite to the bottom surface of part of the bare aluminum sheet, and the pole, the insulating layer and the bare aluminum sheet together constitute the top cover; providing a wound battery cell , the wound battery cell includes a plurality of wound pole pieces and a diaphragm, the diaphragm is located between adjacent pole pieces, and the end of the pole piece has a pole ear; a first welding process is performed on the end of at least one of the pole ears close to the pole piece; a second welding process is performed on the pole ear and the adapter sheet, wherein the adapter sheet has a second groove; the wound battery cell and the top cover are assembled, and the wound battery cell and the top cover are squeezed so that the end of the pole away from the extension portion is located in the second groove, and the sealing ring fills the groove; a third welding process is performed on the pole column and the adapter sheet, including: the third welding process is performed on the pole column and the adapter sheet corresponding to the second groove through the bottom surface of the first groove except the protruding portion, and a first welding layer is formed; the outer shell and the wound battery cell are assembled and a fourth welding process is performed, and the fourth welding process is used to fix the outer shell and the top cover.

[0007] In some embodiments, when the top cover is assembled, the thickness of the sealing ring is greater than the width of the groove along the first direction.

[0008] In some embodiments, before assembling the top cover, the thickness of the sealing ring along the first direction is D1; ​​after assembling the wound battery cell and the top cover, the thickness of the sealing ring along the first direction is D2, and the difference between D1 and D2 is greater than or equal to the depth of the second groove.

[0009] In some embodiments, the adapter plate has a first area and a second area, the pole ear is welded to the first area, and the second area of ​​the adapter plate has the second groove inside; when the pole ear and the adapter plate are welded, the first area of ​​the adapter plate is thinned.

[0010] In some embodiments, the thickness of the main body corresponding to the bottom surface of the first groove excluding the protrusion is 0.5mm~3mm; the process parameters of the third welding treatment include: the shielding gas flow rate is 30L / min~90L / min, the power is 1100W~2000W, and the welding speed is 0.4m / s~0.6m / s.

[0011] In some embodiments, the cross-sectional shape of the first welding layer along a surface perpendicular to the adapter sheet includes a trapezoid, the size of the top surface of the first welding layer ranges from 0.8 mm to 2 mm, and the size of the height of the first welding layer ranges from 0.4 mm to 0.8 mm.

[0012] In some embodiments, before performing the second welding process on the electrode tab and the adapter, the method further includes: bending the electrode tab so that the electrode tab is located at an end of the adapter away from the wound battery cell.

[0013] According to some embodiments of the present application, another aspect of the embodiments of the present application provides a secondary battery, comprising: a top cover and an outer shell, wherein the top cover and the outer shell form a chamber; the top cover comprises: a bare aluminum sheet, an insulating layer, a pole and a sealing ring; the bare aluminum sheet has a pole through hole, and the pole passes through the pole through hole; the insulating layer is located between the pole and the bare aluminum sheet, the sealing ring is located on a side of the bare aluminum sheet away from the insulating layer, and the sealing ring surrounds a groove of the pole; the pole comprises: a main body portion, wherein the main body portion has a first groove inside; an extension portion, wherein the extension portion extends from the main body portion in a direction away from the first groove; a protrusion portion, wherein the protrusion portion is located on a portion of the bottom surface of the first groove, The protrusion protrudes toward the opening direction of the first groove; wherein the side surface of the main body has the groove recessed toward the direction of the first groove; a wound battery cell, the wound battery cell is located in the chamber; the wound battery cell includes: a plurality of wound pole pieces and a diaphragm, the diaphragm is located between adjacent pole pieces, and the end of the pole piece has a pole ear; a transition piece, the transition piece has a first area and a second area, the pole ear is welded to the first area, the interior of the second area of ​​the transition piece has a second groove, and the end of the pole is located in the second groove; a first welding layer, the first welding layer includes a first portion located in the pole column and a second portion in the second area of ​​the transition piece.

[0014] In some embodiments, the pole ear includes an integrally formed bending portion and a connecting portion, the bending portion is connected to the pole piece, the connecting portion is located between the adapter sheet and the bare aluminum sheet, and the connecting portion is welded to the adapter sheet.

[0015] According to some embodiments of the present application, on the other hand, embodiments of the present application provide a method for preparing an energy storage battery pack, comprising: providing a secondary battery prepared by the method for preparing a secondary battery as described in any one of the above embodiments or a secondary battery as described in any one of the above embodiments; performing laser welding on the pole and the tab of the secondary battery, the tab having a recessed portion, the recessed portion being recessed inwardly, the recessed portion being located in the first groove, performing a fifth welding process through the recessed portion and the protruding portion, and forming a second welding layer.

[0016] In some embodiments, the thickness of the protrusion is 1mm~5mm; the welding power of the fifth welding process is 4000W~8000W; the size range of the top surface of the second welding layer is 0.8mm~2mm, and the size range of the height of the second welding layer is 0.8mm~1.5mm.

[0017] According to some embodiments of the present application, on the other hand, embodiments of the present application provide an energy storage battery pack, comprising: a secondary battery prepared by the method for preparing a secondary battery as described in any one of the above embodiments or a secondary battery as described in any one of the above embodiments; a tab, wherein the tab is located on a side of the pole away from the wound battery cell; the tab has a recessed portion, wherein the recessed portion is recessed inwardly, and the recessed portion is located in a first groove of the pole; a second welding layer, wherein the second welding layer includes a third portion located in the recessed portion and a fourth portion located in a protruding portion of the pole.

[0018] The technical solution provided by the embodiments of the present application has at least the following advantages: The preparation method of the secondary battery provided in the embodiment of the present application designs the pole so that the pole has a main body, an extension, a protrusion and a groove, so that the inner side surface of the sealing ring corresponds to the groove of the pole, and the top surface of the sealing ring is opposite to the bottom surface of the partially bare aluminum sheet, and the pole is fixed by the sealing ring, and then the adapter plate and the winding battery cell are extruded and the first welding process is performed, so that the top cover including the pole and the winding battery cell can be tightly engaged, and the sealing and reliability are good, and the height of the pole and the height of the top cover can also be reduced; secondly, the sealing ring can be engaged in the groove by the position of the sealing ring, the groove design of the pole and the second groove design of the adapter plate, which not only achieves better sealing, but also reduces the height occupied by the sealing ring, thereby improving the volume utilization of the secondary battery. Secondly, a third welding process is performed on the bottom surface corresponding to the first groove of the pole and the adapter plate to form a first welding layer. The setting of the first groove can reduce the height of the solder and shorten the height of the pole. The height of the pole and the heat generation of the pole can be reduced through the design of the pole, the clamping position of the sealing ring, and the method and position of the third welding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] One or more embodiments are exemplarily illustrated by the figures in the corresponding drawings. These exemplified descriptions do not constitute a limitation on the embodiments. Unless otherwise specified, the figures in the drawings do not constitute a scale limitation. In order to more clearly illustrate the embodiments of the present application or the technical solutions in the traditional technology, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A flow chart of a method for preparing a secondary battery provided in one embodiment of the present application; Figure 2 A schematic diagram of a three-dimensional structure of a top cover provided in one embodiment of the present application; Figure 3 for Figure 2 A schematic diagram of a cross-sectional structure along the A1-A2 section; Figure 4 An exploded view of a top cover provided in one embodiment of the present application; Figure 5 A schematic diagram of a three-dimensional structure of a pole provided in one embodiment of the present application; Figure 6 for Figure 5 A schematic diagram of a cross-sectional structure along the B1-B2 section; Figure 7 A schematic diagram of another three-dimensional structure of a pole provided in one embodiment of the present application; Figure 8 A schematic diagram of a three-dimensional structure of a wound battery cell and a switching sheet provided in one embodiment of the present application; Fig. 9 for Figure 8 A schematic diagram of a cross-sectional structure along the C1-C2 section; Fig.10 A schematic diagram of a three-dimensional structure of an adapter provided in one embodiment of the present application; Fig.11 for Fig.10 A schematic diagram of a cross-sectional structure along the E1-E2 section; Fig.12 A cross-sectional view of a top cover and an adapter sheet provided in one embodiment of the present application; Fig.13 An exploded diagram of a secondary battery provided in one embodiment of the present application; Fig.14 A schematic diagram of a three-dimensional structure of a secondary battery provided in one embodiment of the present application; Fig.15A top view of a secondary battery provided in one embodiment of the present application; Fig.16 A schematic diagram of a three-dimensional structure of a bar provided in an embodiment of the present application; Fig.17 Another schematic diagram of a three-dimensional structure of a bar sheet provided in an embodiment of the present application; Fig.18 A schematic diagram of a three-dimensional structure of an energy storage battery pack provided in one embodiment of the present application; Fig.19 A schematic diagram of a three-dimensional structure of a bar and a pole provided in an embodiment of the present application; Fig. 20 for Fig.19 A schematic diagram of a cross-sectional structure along the F1-F2 section; Fig.21 An exploded diagram of an energy storage battery pack provided in one embodiment of the present application. DETAILED DESCRIPTION

[0021] As can be seen from the background technology, the current pole height is relatively high, which results in a low volume utilization rate of the secondary battery.

[0022] The embodiments of the present application provide a secondary battery and a method for preparing the same, an energy storage battery pack and a method for preparing the same. By designing the first groove and the groove of the pole, and coordinating the engagement method of the sealing ring and the welding position and the welding method of the pole and the adapter, the height and heat generation of the pole are reduced, thereby improving the volume utilization of the secondary battery.

[0023] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0025] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists, A and B exist at the same time, and B exists. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0026] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0027] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the embodiments of the present application.

[0028] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0029] In the accompanying drawings corresponding to the embodiments of the present application, the thickness and area of ​​the layer are magnified for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on another component or on the surface of another component, the component may be "directly" located on the surface of the other component, or a third component may be present between the two components. On the contrary, when describing a component on the surface of another component or when another component is formed or provided on the surface of a component, it means that there is no third component between the two components. In addition, when describing a component as "substantially" formed on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor is it formed on a partial edge of the entire surface.

[0030] In the description of the embodiments of the present application, when a component "includes" another component, unless otherwise specified, other components are not excluded, and other components may be further included. In addition, when a component such as a layer, film, region, or plate is referred to as "on / located on" another component, it can be "directly on" the other component (i.e., located on the surface of the other component with no other components between them), or another component may exist in between. In addition, when a component such as a layer, film, region, or plate is "directly located on" another component, or when a component such as a layer, film, region, or plate is located on the surface of another component, it means that no other components are located in between.

[0031] The terms used in the description of the various embodiments described herein are only used to describe specific embodiments and are not intended to be limiting. As used in the description of the various embodiments described and in the appended claims, "the part" is also intended to include the plural form unless the context clearly indicates otherwise. Among them, a component includes a layer, a film, a region, or a plate.

[0032] The following will describe the various embodiments of the present application in detail with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that in the various embodiments of the present application, many technical details are provided in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solution claimed in the present application can be implemented.

[0033] According to some embodiments of the present application, a first aspect of the embodiments of the present application provides a method for preparing a secondary battery, which is used to reduce the height of the pole and improve the photovoltaic utilization rate of the secondary battery. The secondary battery and its preparation method will be described in detail below in conjunction with the relevant drawings.

[0034] refer to Figure 1The preparation method includes: forming a pole, the pole includes: a main body, the main body has a first groove inside; an extension part, the extension part extends from the main body in a direction away from the first groove; a protrusion, the protrusion is located on a part of the bottom surface of the first groove, and the protrusion protrudes toward the opening direction of the first groove; wherein the side of the main body has a groove recessed toward the first groove; assembling a top cover, the pole passes through the insulating layer and the pole through hole of the bare aluminum sheet in sequence and extends to the other end of the bare aluminum sheet, the sealing ring engages the end of the pole, and the inner side of the sealing ring corresponds to the groove of the pole, the top surface of the sealing ring is opposite to the bottom surface of part of the bare aluminum sheet, and the pole, the insulating layer and the bare aluminum sheet together constitute the top cover; providing a wound battery cell, the wound battery cell includes a plurality of wound A pole piece and a diaphragm, the diaphragm is located between adjacent pole pieces, and the end of the pole piece has a pole ear; a first welding process is performed on the end of at least one pole ear of the pole piece close to the pole piece; a second welding process is performed on the pole ear and the adapter, wherein the adapter has a second groove; the wound battery cell and the top cover are assembled, and the wound battery cell and the top cover are squeezed so that the end of the pole away from the extension portion is located in the second groove, and the sealing ring fills the groove; a third welding process is performed on the pole and the adapter, including: a third welding process is performed on the pole and the adapter corresponding to the second groove through the bottom surface of the first groove except the protruding portion, and a first welding layer is formed; the outer shell and the wound battery cell are assembled and a fourth welding process is performed, and the fourth welding process is used to fix the outer shell and the top cover.

[0035] The preparation method of the secondary battery provided in the embodiment of the present application designs the pole so that the pole has a main body, an extension, a protrusion and a groove, so that the inner side surface of the sealing ring corresponds to the groove of the pole, and the top surface of the sealing ring is opposite to the bottom surface of the partially bare aluminum sheet, and the pole is fixed by the sealing ring, and then the adapter plate and the winding battery cell are extruded and the first welding process is performed, so that the top cover including the pole and the winding battery cell can be tightly engaged, and the sealing and reliability are good, and the height of the pole and the height of the top cover can also be reduced; secondly, the sealing ring can be engaged in the groove by the position of the sealing ring, the groove design of the pole and the second groove design of the adapter plate, which not only achieves better sealing, but also reduces the height occupied by the sealing ring, thereby improving the volume utilization of the secondary battery. Secondly, a third welding process is performed on the bottom surface corresponding to the first groove of the pole and the adapter plate to form a first welding layer. The setting of the first groove can reduce the height of the solder and shorten the height of the pole. The height of the pole and the heat generation of the pole can be reduced through the design of the pole, the clamping position of the sealing ring, and the method and position of the third welding process.

[0036] In some embodiments, reference Figure 2 , Figure 3 as well as Figure 4, assemble the top cover, which is used to reduce overcurrent and the probability of the flip plate being melted to prevent the battery from catching fire and exploding. The top cover may include: a pole 110, an insulating layer 107, a bare aluminum sheet 101, a sealing ring 108, an explosion-proof valve sealing ring 109, and an explosion-proof sheet 103.

[0037] In some embodiments, reference Figure 5 , Figure 6 as well as Figure 7 The process steps for forming the pole 110 include: providing a plate, and then performing a stretching process on the plate, so as to obtain a semi-finished pole having a first groove 114, an extension portion 112 and a main body portion 111; and then performing fine turning on the semi-finished pole, so that a protrusion 113 is formed in the first groove 114 and a groove 115 is formed on the side of the main body portion 111.

[0038] In some embodiments, the stretching process may be an extrusion stretching process, that is, the semi-finished pole is formed by an extrusion stretching process, so that the pole 110 itself has a higher strength, avoiding the problem of breakage or melting when the pole 110 is subsequently welded to the bar.

[0039] In some embodiments, the protrusion 113 may be formed by thinning the bottom surface of the first groove 114 to thin a portion of the area close to the main body 111 . Correspondingly, the protrusion 113 protrudes toward the opening direction of the first groove 114 in a portion of the area relatively close to the main body 111 .

[0040] In some embodiments, the pole 110 includes a positive pole and a negative pole. The positive pole is used to connect to the adapter corresponding to the positive electrode sheet and to the positive electrode sheet; the negative pole is used to connect to the adapter corresponding to the negative electrode sheet and to the negative electrode sheet.

[0041] In some embodiments, the pole 110 can be made of aluminum or aluminum alloy. The positive pole is made of aluminum and the negative pole is made of copper-aluminum composite plate, so that there is a good path between the positive pole and the shell, eliminating the potential difference between the positive pole and the shell, thereby avoiding corrosion of the shell.

[0042] The main body has opposite inner and outer sides, the inner wall of the first groove is the inner side of the main body, the groove is formed on the outer side of the main body, and the groove is located at one end of the main body away from the extension portion.

[0043] In some embodiments, reference Figure 6 , the groove 115 is along the first direction Y2 (reference Figure 4) has a width L in the range of 0.8 mm to 2 mm. The width L of the groove 115 along the first direction Y2 may range from 0.8 mm to 1.0 mm, 1.0 mm to 1.2 mm, 1.2 mm to 1.4 mm, 1.4 mm to 1.6 mm, 1.6 mm to 1.8 mm, or 1.8 mm to 2.0 mm. The width L of the groove 115 along the first direction Y2 may range from 0.9 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.7 mm, or 1.9 mm.

[0044] In some embodiments, there is an insulating layer 107 between the pole 110 and the bare aluminum sheet 101. The insulating layer 107 can achieve insulation between the positive pole and the outer shell and between the negative pole and the outer shell. By achieving insulation between the positive pole and the outer shell, the potential difference between the positive pole and the outer shell can be eliminated, and the problem of outer shell corrosion can be avoided; by achieving insulation between the negative pole and the outer shell, the insulating material can avoid a short circuit between the positive and negative poles.

[0045] In some embodiments, the material of the insulating layer 107 may be silicon nitride.

[0046] In some embodiments, the light aluminum sheet 101 has a pole through hole 1011 (refer to Figure 4 ), explosion-proof valve through hole and liquid injection port 102, explosion-proof sheet 103 is assembled toward the plain aluminum sheet 101 along the first direction Y2, explosion-proof valve sealing ring 109 is assembled toward the plain aluminum sheet 101 along the second direction Y1, and explosion-proof sheet 103 and explosion-proof valve sealing ring 109 are engaged through the explosion-proof valve through hole. The first direction Y2 and the second direction Y1 are opposite directions, that is, the angle between the two is 180°.

[0047] In some embodiments, the sealing ring 108 is a fluororubber sealing ring or a ceramic sealing ring.

[0048] In some embodiments, since the sealing ring 108 is sleeved on the positive electrode column and the negative electrode column, it can be ensured that there is no air leakage at the positive electrode column and the negative electrode column, thereby improving the overall air tightness of the secondary battery.

[0049] In some embodiments, reference Figure 8 , providing a wound battery cell 130, the wound battery cell 130 includes a positive electrode sheet, a separator and a negative electrode sheet stacked in sequence, and the battery cell obtained by winding the positive electrode sheet, the separator and the negative electrode sheet is the wound battery cell.

[0050] refer to Figure 8 as well as Fig. 9 The end of the positive electrode sheet has a tab 131, which is used to connect with the adapter sheet 120, the pole 110 and the subsequent positive electrode bar sheet for transmitting current. The number of tabs 131 can be one or more. Similarly, the end of the negative electrode sheet also has a tab 131.

[0051] In some embodiments, the pole tab 131 is subjected to a first welding process, which causes an initial bend to occur on one side of the pole tab 131 close to the positive electrode sheet, thereby forming a bent portion 1311 during a subsequent bending process, and the remaining pole tab is a connecting portion 1312 .

[0052] The specific steps are as follows: fold the pole ear of the wound battery cell to ensure that the connection between the pole ear and the pole piece body is flat and tight. The folded pole ear can be shaped to enhance the fit between the pole ear and the pole piece body, providing a stable contact basis for subsequent welding. After the first folding of the pole ear, welding technology, such as laser welding or ultrasonic welding, is used to perform the first pre-welding treatment on the pole ear. This step is intended to initially fix the position of the pole ear and ensure that the electrical connection between the pole ear and the pole piece body is reliable, providing a stable electrical performance basis for subsequent processes. Secondly, after the first pre-welding is completed, the pole ear is folded a second time to reduce the space occupied by the pole ear, ensure that the multi-layer pole ear is in more complete contact, and provide the best welding conditions for the second pre-welding. On the basis of the second folding and shaping, the pole ear is pre-welded for the second time. In order to make rational use of space, the directions of the first folding and the second folding are opposite, and the width of the pre-welded tab assembly after the second folding is less than or equal to the thickness of the wound battery cell, so that the pre-welded tab assembly can be accommodated on one side of the wound battery cell, which is convenient for rational use of the space of the battery casing.

[0053] In some embodiments, before performing the second welding process on the electrode tab 131 and the adapter plate 120 , the process further includes: bending the electrode tab 131 so that the electrode tab 131 is located at an end of the adapter plate 120 away from the wound battery cell 130 .

[0054] refer to Fig. 9 , a second welding process is performed on the pole ear 131 and the adapter plate 120. The second welding process is used to weld the pole ear 131 and the adapter plate 120 so as to form a good connection performance between the pole ear 131 and the adapter plate 120. During this process, the bent portion 1311 of the pole ear 131 continues to fold in the direction of the first folding, and the connecting portion 1312 abuts against the surface of the adapter plate 120.

[0055] In some embodiments, reference Fig.10 as well as Fig.11The adapter sheet 120 has a first region 121 and a second region 122, the tab 131 is welded to the first region 121, and the second region 122 of the adapter sheet 120 has a second groove 123 inside; when the tab 131 and the adapter sheet 120 are welded, the first region 121 of the adapter sheet 120 is thinned to a thickness of H1. In this way, the height of the secondary battery can be further reduced, thereby improving the volume utilization rate of the secondary battery.

[0056] In some embodiments, the depth H2 of the second groove 123 is the same as the distance between the groove and the end of the pole 110 .

[0057] In some embodiments, the wound cell 130 and the top cover are assembled, and the wound cell 130 and the top cover are squeezed so that the end of the pole 110 away from the extension 112 is located in the second groove 123 , and the sealing ring 108 fills the groove 115 .

[0058] In some embodiments, when assembling the top cover, the thickness of the sealing ring 108 is greater than the width of the groove 115 along the first direction; when assembling the wound battery cell 130 and the top cover, the wound battery cell 130 and the top cover are squeezed to allow the sealing ring 108 to fill the groove 115.

[0059] In some embodiments, before assembling the top cover, the thickness of the sealing ring 108 along the first direction is D1; ​​after assembling the wound battery cell and the top cover, the thickness of the sealing ring 108 along the first direction is D2, and the difference between D1 and D2 is greater than or equal to the depth H2 of the second groove 123. The deformation of the sealing ring 108 is equal to the depth of the second groove 123, which shortens the height of the pole 110 while ensuring the sealing between the pole 110 and the upper top cover to prevent leakage.

[0060] It should be noted that the thinned thickness H1 and the depth H2 of the second groove 123 are not limited in the embodiment of the present application. It is only necessary that the pole ear can be located in the first area after bending, and the strength of the first area can meet the subsequent welding process, and the depth of the second groove can meet the end of the pole to be located in the second groove.

[0061] refer to Fig.12 , performing a third welding process on the pole 110 and the adapter 120 , including: performing a third welding process on the pole 110 and the adapter 120 corresponding to the second groove 123 through the bottom surface of the first groove 114 except the protrusion 113 , and forming a first welding layer 124 .

[0062] In some embodiments, the first welding layer includes a first portion located in the pole and a second portion located in the second region of the adapter. The first portion refers to the material layer of the pole that is welded again after laser treatment, and the second portion refers to the material layer of the adapter that is welded again after laser treatment.

[0063] In some embodiments, reference Figure 6 , the thickness t1 of the main body 111 excluding the protrusion 113 corresponding to the bottom surface of the first groove 114 is 0.5 mm to 3 mm. The thickness t1 of the main body 111 excluding the protrusion 113 corresponding to the bottom surface of the first groove 114 can range from 0.5 mm to 1.0 mm, 1.0 mm to 1.5 mm, 1.5 mm to 2.0 mm, 2.0 mm to 2.5 mm, or 2.5 mm to 3.0 mm. The thickness t1 of the main body 111 excluding the protrusion 113 corresponding to the bottom surface of the first groove 114 can range from 0.6 mm, 0.9 mm, 1.1 mm, 1.3 mm, 1.8 mm, 2.3 mm, 2.7 mm, or 2.9 mm.

[0064] In some embodiments, the process parameters of the third welding process include: a shielding gas flow rate of 30 L / min to 90 L / min, a power of 1100 W to 2000 W, and a welding speed of 0.4 m / s to 0.6 m / s. The thickness of the body 111 of the first groove 114 is relatively small, so that the process parameters of the laser welding process are relatively small, and thus a relatively small welding layer can be formed under the premise of good solid line welding.

[0065] In some embodiments, reference Fig.12 The cross-sectional shape of the first welding layer 124 along the direction perpendicular to the surface of the adapter sheet includes a trapezoid, the size W1 of the top surface of the first welding layer 124 ranges from 0.8 mm to 2 mm, and the size range of the height T1 of the first welding layer 124 ranges from 0.4 mm to 0.8 mm.

[0066] refer to Fig.13 as well as Fig.14 , assemble the housing 100 and the wound battery cell 130 and perform a fourth welding process, the fourth welding process is used to fix the housing 100 and the top cover.

[0067] In some embodiments, the top cover also includes: a lower plastic plate 104, which is located on the side of the bare aluminum sheet 101 close to the wound battery cell 130; the end of the lower plastic plate 104 has a clamping portion 105 extending toward the cavity, and the clamping portion 105 is clamped in the outer shell 100, and the clamping portion 105 is used to clamp the Mylar film 106 and weld the Mylar film 106.

[0068] In some embodiments, the number of the engaging portions 105 is 2 to 11. The number of the engaging portions 105 can be 2, 4, 7, 9 or 11.

[0069] In some embodiments, the process of assembling the housing 100 and the wound battery cell 130 further includes assembling a Mylar film 106 , where the Mylar film 106 is located between the housing 100 and the wound battery cell 130 .

[0070] The height of conventional poles is about 3 mm or more, while the height of the poles in the secondary battery prepared by the secondary battery preparation method provided in the embodiment of the present application can be reduced to about 2 mm, with a reduction ratio of more than 30%, thereby greatly shortening the height of the poles.

[0071] The manufacturing method of the secondary battery provided in the embodiment of the present application is to design the pole 110 so that the pole 110 has a body portion 111, an extension portion 112, a protrusion 113 and a groove 115, so that the inner side surface of the sealing ring 108 corresponds to the groove 115 of the pole 110, and the top surface of the sealing ring 108 is opposite to the bottom surface of the partially bare aluminum sheet 101, and then the pole 110 is fixed by the sealing ring 108, and then the adapter sheet 120, the extrusion treatment of the wound battery cell 130 and the first welding process are performed. The top cover including the pole 110 and the wound battery cell 130 can be tightly engaged, and the sealing and reliability are good, and the height of the pole 110 and the top cover can also be reduced; secondly, by adjusting the position of the sealing ring 108, the groove 115 of the pole 110 and the second groove 123 of the adapter 120, the sealing ring 108 can be engaged in the groove 115, which not only achieves good sealing, but also reduces the height occupied by the sealing ring 108, thereby improving the volume utilization rate of the secondary battery. Secondly, the bottom surface corresponding to the first groove 114 of the pole 110 and the adapter 120 are subjected to the third welding process to form the first welding layer 124. The setting of the first groove 114 can reduce the height of the solder and shorten the height of the pole 110. The design of the pole 110, the engagement position of the sealing ring 108, the method of the third welding process and the position of the pole 110 can reduce the height of the pole 110 and reduce the heat generated by the pole 110.

[0072] Correspondingly, another aspect of the embodiment of the present application further provides a secondary battery, which can be prepared by the secondary battery preparation method provided in the previous embodiment. The technical features that are the same as or corresponding to the above embodiment will not be described in detail here.

[0073] refer to Figure 12~Figure 15A secondary battery comprises: a top cover and an outer shell 100, the top cover and the outer shell 100 enclose a chamber; the top cover comprises: a bare aluminum sheet 101, an insulating layer 107, a pole 110 and a sealing ring 108; the bare aluminum sheet 101 has a pole through hole 1011, the pole 110 passes through the pole through hole 1011, the insulating layer 107 is located between the pole 110 and the bare aluminum sheet 101, the sealing ring 108 is located on the side of the bare aluminum sheet 101 away from the insulating layer 107, and the sealing ring 108 surrounds the groove 115 of the pole 110; the pole 110 comprises: a main body 111, the main body 111 has a first groove 114 inside; an extension 112, the extension 112 extends from the main body 111 in a direction away from the first groove 114; a protrusion 113, the protrusion 113 is located on a part of the bottom surface of the first groove 114, and the protrusion 113 protrudes toward the opening direction of the first groove 114; wherein the main body The side surface of 111 away from the extension portion 112 has a groove 115 recessed toward the first groove 114; wherein the insulating layer 107 is also located between the extension portion 112 and the bare aluminum sheet 101; part of the sealing ring 108 is engaged in the groove 115; a wound battery cell, the wound battery cell 130 is located in the chamber; the wound battery cell 130 includes: a plurality of wound pole pieces and a diaphragm, the diaphragm is located between adjacent pole pieces, and the end of the pole piece has a pole ear 131; a transfer plate 120, the transfer plate 120 has a first area 121 and a second area 122, the pole ear 131 is welded to the first area 121, the second area 122 of the transfer plate 120 has a second groove 123 inside, and the end of the pole 110 is located in the second groove 123; a first welding layer 124, the first welding layer 124 includes a first portion located in the pole 110 and a second portion in the second area 122 of the transfer plate 120.

[0074] In some embodiments, reference Figure 4 The top cover may include: a pole 110 , an insulating layer 107 , a bare aluminum sheet 101 , a sealing ring 108 , an explosion-proof valve sealing ring 109 , and an explosion-proof sheet 103 .

[0075] In some embodiments, the pole 110 includes a positive pole and a negative pole.

[0076] In some embodiments, reference Figure 6 , the groove 115 is along the first direction Y2 (reference Figure 4 ) has a width L range of 0.8mm~2mm.

[0077] In some embodiments, reference Figure 4 The bare aluminum sheet 101 has a pole through hole 1011, an explosion-proof valve through hole and a liquid injection port 102, and the explosion-proof sheet 103 is engaged with the explosion-proof valve sealing ring 109 through the explosion-proof valve through hole.

[0078] In some embodiments, the pole ear 131 includes an integrally formed bending portion 1311 and a connecting portion 1312 , the bending portion 1311 is connected to the pole piece, the connecting portion 1312 is located between the adapter plate 120 and the bare aluminum sheet 101 , and the connecting portion 1312 is welded to the adapter plate 120 .

[0079] In some embodiments, the top cover also includes: a lower plastic plate 104, which is located on the side of the bare aluminum sheet 101 close to the wound battery cell 130; the end of the lower plastic plate 104 has a snap-fitting portion 105 extending toward the cavity, and the snap-fitting portion 105 is snap-fitted into the outer shell 100; the number of the snap-fitting portions 105 is 2 to 11.

[0080] In some embodiments, the top surface of the adapter sheet 120 facing the top cover is higher than or flush with the surface of the groove 115 facing the wound battery cell 130 .

[0081] In some embodiments, the thickness t1 of the body portion 111 excluding the protrusion 113 corresponding to the bottom surface of the first groove 114 is 0.5 mm to 3 mm. The cross-sectional shape of the first welding layer 124 along the vertical direction to the surface of the adapter sheet includes a trapezoid, the size W1 of the top surface of the first welding layer 124 ranges from 0.8 mm to 2 mm, and the size range of the height T1 of the first welding layer 124 is 0.4 mm to 0.8 mm.

[0082] Correspondingly, another aspect of the embodiments of the present application further provides a method for preparing an energy storage battery pack, comprising: providing a secondary battery prepared by the method for preparing a secondary battery as in any of the above embodiments or a secondary battery as in any of the above embodiments, and the technical features that are the same or corresponding to the above embodiments will not be described in detail here.

[0083] refer to Figure 16~Figure 21 The preparation method includes: providing a secondary battery prepared by the preparation method of a secondary battery as in any one of the above embodiments or a secondary battery as in any one of the above embodiments; performing laser welding on the pole 110 and the tab 210 of the secondary battery, the tab 210 having a recessed portion 211, the recessed portion 211 being recessed inwardly, the recessed portion 211 being located in the first groove 114, performing a fifth welding process through the recessed portion 211 and the protruding portion, and forming a second welding layer 212.

[0084] In some embodiments, reference Figure 6, the thickness t2 of the protrusion is 1mm~5mm. The thickness t2 of the protrusion can range from 1.0mm~1.5mm, 1.5mm~2.0mm, 2.0mm~2.5mm, 2.5mm~3.0mm, 3.0mm~3.5mm, 3.5mm~4.0mm, 4.0mm~4.5mm or 4.5mm~2.0mm. The thickness t2 of the protrusion can range from 1.3mm, 1.8mm, 2.3mm, 2.7mm, 3.2mm, 3.7mm, 4.3mm, 4.7mm or 4.9mm.

[0085] In some embodiments, the welding power of the fifth welding process is 4000W~8000W.

[0086] In some embodiments, reference Fig. 20 The cross-sectional shape of the second welding layer 212 along the direction perpendicular to the surface of the adapter sheet includes a trapezoid, the size W2 of the top surface of the second welding layer 212 ranges from 0.8 mm to 2 mm, and the size range of the height T2 of the second welding layer 212 ranges from 0.8 mm to 1.5 mm.

[0087] In some embodiments, the second welding layer includes a third portion located in the concave portion and a fourth portion located in the protruding portion of the pole. The third portion refers to the material layer of the bar sheet that is welded again after laser treatment, and the second portion refers to the material layer of the pole that is welded again after laser treatment.

[0088] In some embodiments, the tab 210 includes a positive tab and a negative tab, the positive tab is welded to the positive electrode post, and the negative tab is welded to the negative electrode post.

[0089] The method for preparing the energy storage battery pack provided in the embodiment of the present application designs the first groove 114 of the pole 110 and the recessed portion 211 of the tab 210, so that the recessed portion 211 of the tab 210 is located in the first groove 114 of the pole 110 and abuts against the protruding portion, thereby shortening the height of the pole 110 and the tab 210. Secondly, the welding area between the tab 210 and the pole 110 is located in the recessed portion 211, which can reduce the height of the solder or the welding layer, thereby shortening the height of the secondary battery, thereby improving the volume utilization rate.

[0090] Correspondingly, another aspect of the embodiments of the present application further provides an energy storage battery pack, including: a secondary battery prepared by the method for preparing a secondary battery in any of the above embodiments or a secondary battery in any of the above embodiments, and technical features that are the same or corresponding to the above embodiments will not be described in detail here.

[0091] refer to Fig. 20 and Fig.21, a storage battery pack, comprising: a secondary battery prepared by the method for preparing a secondary battery as in any one of the above embodiments or a secondary battery as in any one of the above embodiments; a tab 210, the tab 210 is located on the side of the pole 110 away from the wound battery cell; the tab 210 has a recessed portion 211, the recessed portion 211 is recessed inwardly, and the recessed portion 211 is located in the first groove 114 of the pole 110; a second welding layer 212, the second welding layer 212 includes a third portion located in the recessed portion 211 and a fourth portion located in the protruding portion of the pole 110.

[0092] In some embodiments, the tab 210 includes a positive tab and a negative tab, the positive tab is welded to the positive electrode post, and the negative tab is welded to the negative electrode post.

[0093] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes may be made to the embodiments in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present application, and therefore the scope of protection of the present application shall be subject to the scope defined in the claims.

Claims

1. A method for preparing a secondary battery, characterized in that: include: A pole is formed, the pole comprising: a main body, the main body having a first groove inside; an extension portion, the extension portion extending from the main body in a direction away from the first groove; a protrusion, the protrusion is located on a part of the bottom surface of the first groove, the protrusion protrudes toward the opening direction of the first groove; wherein the side surface of the main body has a groove recessed toward the first groove; Assemble the top cover, wherein the pole passes through the insulating layer and the pole through hole of the bare aluminum sheet in sequence and extends to the other end of the bare aluminum sheet, the sealing ring engages the end of the pole, and the inner side surface of the sealing ring corresponds to the groove of the pole, the top surface of the sealing ring is opposite to the bottom surface of part of the bare aluminum sheet, and the pole, the insulating layer and the bare aluminum sheet together constitute the top cover; A wound battery cell is provided, wherein the wound battery cell comprises a plurality of wound pole pieces and a separator, wherein the separator is located between adjacent pole pieces, and ends of the pole pieces have pole ears; Performing a first welding process on an end portion of at least one of the pole ears of the pole piece close to the pole piece; Performing a second welding process on the tab and the adapter, wherein the adapter has a second groove; Assembling the wound battery cell and the top cover, and squeezing the wound battery cell and the top cover so that one end of the pole away from the extension portion is located in the second groove, and the sealing ring fills the groove; Performing a third welding process on the pole and the adapter, including: performing the third welding process on the pole and the adapter corresponding to the second groove through the bottom surface of the first groove except the protruding portion, and forming a first welding layer; The outer shell and the wound battery core are assembled and a fourth welding process is performed, wherein the fourth welding process is used to fix the outer shell and the top cover.

2. The method for preparing a secondary battery according to claim 1, characterized in that: When the top cover is assembled, the thickness of the sealing ring is greater than the width of the groove along the first direction.

3. The method for preparing a secondary battery according to claim 2, characterized in that: Before assembling the top cover, the thickness of the sealing ring along the first direction is D1; ​​after assembling the wound battery cell and the top cover, the thickness of the sealing ring along the first direction is D2, and the difference between D1 and D2 is greater than or equal to the depth of the second groove.

4. The method for preparing a secondary battery according to claim 1, characterized in that: The adapter plate has a first area and a second area, the pole tab is welded to the first area, and the second area of ​​the adapter plate has the second groove inside; when the pole tab and the adapter plate are welded, the first area of ​​the adapter plate is thinned.

5. The method for preparing a secondary battery according to claim 1, characterized in that: The thickness of the main body corresponding to the bottom surface of the first groove excluding the protruding portion is 0.5mm~3mm; the process parameters of the third welding treatment include: the shielding gas flow rate is 30L / min~90L / min, the power is 1100W~2000W, and the welding speed is 0.4m / s~0.6m / s.

6. The method for preparing a secondary battery according to claim 1 or 5, characterized in that: The cross-sectional shape of the first welding layer along the surface perpendicular to the adapter sheet includes a trapezoid, the size of the top surface of the first welding layer ranges from 0.8 mm to 2 mm, and the size of the height of the first welding layer ranges from 0.4 mm to 0.8 mm.

7. The method for preparing a secondary battery according to claim 1, characterized in that: Before performing the second welding process on the pole tab and the adapter, the method further includes: bending the pole tab so that the pole tab is located at an end of the adapter away from the wound battery cell.

8. A secondary battery, characterized in that: include: A top cover and a shell, wherein the top cover and the shell enclose a chamber; The top cover comprises: a bare aluminum sheet, an insulating layer, a pole and a sealing ring; the bare aluminum sheet has a pole through hole, and the pole passes through the pole through hole; the insulating layer is located between the pole and the bare aluminum sheet, the sealing ring is located on the side of the bare aluminum sheet away from the insulating layer, and the sealing ring surrounds the groove of the pole; the pole comprises: a main body, the inside of the main body has a first groove; an extension part, the extension part extends from the main body in a direction away from the first groove; a protruding part, the protruding part is located on a part of the bottom surface of the first groove, and the protruding part protrudes toward the opening direction of the first groove; wherein the side surface of the main body has the groove recessed toward the direction of the first groove; A wound battery cell, the wound battery cell is located in the chamber; the wound battery cell comprises: a plurality of wound pole pieces and a diaphragm, the diaphragm is located between adjacent pole pieces, and the ends of the pole pieces have pole ears; A transfer plate, the transfer plate having a first area and a second area, the pole ear being welded to the first area, the second area of ​​the transfer plate having a second groove inside, and the end of the pole being located in the second groove; A first welding layer, wherein the first welding layer includes a first portion located in the pole and a second portion in the second area of ​​the adapter.

9. The secondary battery according to claim 8, characterized in that: The pole ear includes an integrally formed bending portion and a connecting portion, the bending portion is connected to the pole piece, the connecting portion is located between the adapter sheet and the bare aluminum sheet, and the connecting portion is welded to the adapter sheet.

10. A method for preparing an energy storage battery pack, characterized in that: include: Providing a secondary battery prepared by the method for preparing a secondary battery according to any one of claims 1 to 7 or a secondary battery according to any one of claims 8 to 9; The pole and the tab of the secondary battery are laser welded, the tab has a recessed portion, the recessed portion is recessed inwardly, the recessed portion is located in the first groove, a fifth welding process is performed through the recessed portion and the protruding portion, and a second welding layer is formed.

11. The method for preparing an energy storage battery pack according to claim 10, characterized in that: The thickness of the protrusion is 1mm~5mm; the welding power of the fifth welding process is 4000W~8000W; the size range of the top surface of the second welding layer is 0.8mm~2mm, and the size range of the height of the second welding layer is 0.8mm~1.5mm.

12. An energy storage battery pack, characterized in that: include: A secondary battery prepared by the method for preparing a secondary battery according to any one of claims 1 to 7 or a secondary battery according to any one of claims 8 to 9; A tab, the tab is located on a side of the pole away from the wound battery core; the tab has a recessed portion, the recessed portion is recessed inwardly, and the recessed portion is located in the first groove of the pole; The second welding layer includes a third portion located in the recessed portion and a fourth portion located in the protruding portion of the pole.

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