Square lithium-ion battery and method of manufacturing the same

Abstract

The present application relates to the technical field of lithium ion battery manufacturing, and discloses a square lithium ion battery and a preparation method thereof, which comprises the following steps: welding a soft connection with a tab on a winding core; sleeving the soft connection on a pole and welding the soft connection on a low-position step of the pole; sleeving a sealing ring on the pole and a first plastic piece on the sealing ring; sequentially installing an insulating film, a top cover sheet, an insulating ceramic, a second plastic piece and a conductive block around the pole from top to bottom; wherein the insulating film is clamped between the first plastic piece and the top cover sheet; riveting the pole and the conductive block; bending the tab and wrapping the winding core in the insulating film. The battery preparation method and the battery provided by the present application reduce the thickness of the cover plate and improve the energy density of the battery; avoid the hot melting process in the prior art, simplify the assembly process and improve the assembly efficiency; when the specifications of the battery cell remain unchanged, the effective volume of the winding core inside the battery cell can be increased, and the energy density of the battery can be increased.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery manufacturing, in particular to a square lithium ion battery and a preparation method thereof. BACKGROUND

[0002] As the most mature commercialized lithium ion battery on the market at present, it is widely used in automobile power supply system due to its high energy density, high cycle and other characteristics. Especially the square lithium ion battery, due to its own structural characteristics, the pack mode is simple and efficient, and the energy density loss after matching is small, so the square lithium ion battery is widely used in automobile power battery.

[0003] The existing assembly method of square lithium ion battery is to weld the soft connection and the matched roll core, then laser weld with the assembled top cover plate, and finally bend the tab and cover the insulating film. The insulating film needs to be fixed with the plastic part in the lower layer of the top cover plate by hot melting. This preparation method mainly has the following problems:

[0004] 1) Since the soft connection needs to be welded with the assembled top cover plate, the soft connection must be welded on the lower surface of the pole, which makes the battery lose at least one soft connection thickness in height space, occupies a large space and reduces the energy density of the battery;

[0005] 2) Since the battery requires an insulating film, the plastic part in the lower layer of the top cover plate must be reserved with a corresponding structure for hot melting with the insulating film, which wastes manpower and material resources, reduces the assembly efficiency, and is not conducive to simplifying the installation process and simplifying the battery structure. SUMMARY

[0006] (I) Technical problems to be solved

[0007] The purpose of the present application is to provide a square lithium ion battery and a preparation method thereof, so as to solve the problems of low assembly efficiency and non-compact structure of the existing square lithium ion battery.

[0008] (II) Technical solutions

[0009] In order to solve the above technical problems, the present application provides a square lithium ion battery preparation method, comprising:

[0010] S1, welding the soft connection and the tab on the matched roll core;

[0011] S2, sleeving the soft connection on the pole, and welding the soft connection on the step surface of the low step of the pole;

[0012] Wherein, the pole comprises a stepped base, and the stepped base comprises the low step and the high step.

[0013] S3, sleeving a sealing ring on the pole column, and sleeving a first plastic piece on the sealing ring;

[0014] S4, sequentially mounting an insulating film, a top cover sheet, an insulating ceramic, a second plastic piece and a conductive block around the pole column from top to bottom; wherein the insulating film is clamped between the first plastic piece and the top cover sheet;

[0015] S5, riveting the pole column and the conductive block;

[0016] S6, bending the tab, and wrapping the winding core in the insulating film.

[0017] The thickness of the soft connection is consistent with the thickness of the high-position step.

[0018] The soft connection comprises a soft connection main body and a tab clamping portion located at both ends of the soft connection main body; a through hole matched with the high-position step is formed in the middle of the soft connection main body.

[0019] The step S1 comprises:

[0020] S11, inserting the tab connected to the winding core into the tab clamping portion;

[0021] S12, welding the tab on the tab clamping portion by ultrasonic welding.

[0022] In the step S2, the soft connection is welded on the step surface of the low-position step by laser welding.

[0023] The application further provides a square lithium ion battery prepared by the square lithium ion battery preparation method.

[0024] The soft connection comprises a soft connection main body and a tab clamping portion located at both ends of the soft connection main body; a through hole matched with the high-position step is formed in the middle of the soft connection main body.

[0025] The bottom surface of the first plastic part is protruded upward to form a hollow boss, and a hole is formed in the middle of the boss for the pole to pass through, and the soft connection body and the stepped base are embedded in the boss.

[0026] The soft connection and the pole lug are welded by ultrasonic welding, and the lower step of the stepped base and the soft connection are welded by laser welding.

[0027] (III) Beneficial effects

[0028] The present application adopts a split structure of the cover plate, and the assembly of the cover plate is completed during the preparation of the battery cell. During the preparation process, the soft connection is sleeved between the pole and the first plastic part by setting an intermediate hole on the soft connection, which reduces the space occupation of the soft connection in the thickness direction of the cover plate, effectively reduces the thickness of the cover plate, and further improves the energy density of the battery. In addition, the assembly of the cover plate is completed during the preparation of the battery cell, without using a pre-assembled cover plate, so that the insulating film can be directly placed between the top cover sheet and the first plastic part by sleeving during the assembly process, and is tightly fixed, avoiding the hot melting process in the prior art, simplifying the assembly process, saving manpower and material resources, and improving the assembly efficiency. In addition, since the first plastic part does not need to reserve a structure for hot melting, the structure of the first plastic part is simplified, the height of the first plastic part is reduced, the space occupation of the battery cell in the height direction is further reduced, and the effective volume of the core inside the battery cell is increased under the premise that the specification and model of the battery cell remain unchanged, thereby increasing the energy density of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 It is a side view of an explosion schematic diagram of a lithium ion battery in the embodiment of the present application;

[0030] Figure 2 It is an isometric side view of Figure 1 ; and

[0031] Figure 3 It is a structure schematic diagram of a pole in the embodiment of the present application;

[0032] Figure 4 It is a structure side view of a soft connection in the embodiment of the present application;

[0033] Figure 5 It is a top view of Figure 4 ; and

[0034] Figure 6 It is a position schematic diagram of ultrasonic welding and laser welding in the embodiment of the present application;

[0035] Figure 7 It is a structure sectional view before riveting of a battery cover plate in the embodiment of the present application;

[0036] Figure 8 Structure sectional view of the battery cover plate after riveting in the embodiment of the present application;

[0037] Figure 9 Schematic view of the square lithium ion battery before being put into the shell in the embodiment of the present application;

[0038] In the figure, 1 is a conductive block; 2 is a second plastic part; 3 is an insulating ceramic; 4 is a top cover sheet; 5 is an insulating film; 6 is a first plastic part; 7 is a roll core; 8 is a sealing ring; 9 is a pole; 91 is a high position step; 911 is a step surface of the high position step; 92 is a low position step; 921 is a step surface of the low position step; 10 is a soft connection; 101 is an ultrasonic welding area; 102 is a laser welding area; 103 is a soft connection body; 1031 is a through hole; 104 is a tab clamping part; 11 is a tab. DETAILED DESCRIPTION

[0039] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but are not used to limit the scope of the present application.

[0040] In the description of the present application, it should be noted that, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present application, it should also be noted that, unless otherwise specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] Figure 1 Side view of the explosion schematic view of the lithium ion battery in the embodiment of the present application; Figure 2 Equiaxial side view of Figure 1 Equiaxial side view of Figure 3 Structure schematic view of the pole in the embodiment of the present application; Figure 4 Structure side view of the soft connection in the embodiment of the present application;Figure 5 is a top view of the embodiment of the present application; Figure 4 is a top view of the embodiment of the present application; Figure 6 is a position schematic view of ultrasonic welding and laser welding in the embodiment of the present application; Figure 7 is a structure sectional view before riveting of the battery cover plate in the embodiment of the present application; Figure 8 is a structure sectional view after riveting of the battery cover plate in the embodiment of the present application; Figure 9 is a schematic view of the square lithium ion battery before entering the shell in the embodiment of the present application.

[0043] The square lithium ion battery preparation method provided by the embodiment of the present application comprises:

[0044] S1, welding the soft connection and the tab on the matched roll core.

[0045] As shown in Figure 1 and Figure 2 , the tab 11 is connected on the roll core 7. As shown in Figure 4 and Figure 5 , the soft connection 10 comprises a soft connection main body 103 and a tab clamping part 104 located at both ends of the soft connection main body 103. The soft connection main body 103 is in a sheet shape, and a square through hole 1031 is formed in the middle, which is matched with the outer shape of the high step 91 of the stepped base on the pole 9. The tab clamping part 104 can clamp the tab 11 on the roll core 7.

[0046] Specifically, the welding process is as follows:

[0047] S11, inserting the tab connected on the roll core into the tab clamping part.

[0048] S12, welding the tab on the tab clamping part by ultrasonic welding. As shown in Figure 2 , there are two roll cores 7, each of which is provided with a tab 11, and the tab clamping part 104 at one end of the soft connection 10 is welded with the tab 11 of one of the roll cores 7, and the tab clamping part 104 at the other end of the soft connection 10 is welded with the tab 11 of the other roll core 7, that is, the soft connection 10 is welded between the two roll cores 7, and the position of the ultrasonic welding area 101 is as shown in Figure 6 .

[0049] S2, sleeving the soft connection on the pole, and welding the soft connection on the step surface of the low step of the pole.

[0050] Among them, the pole comprises a stepped base, and the stepped base comprises a low step and a high step.

[0051] Specifically, the through hole 1031 provided on the soft connection main body 103 can be sleeved on the pole 9, referring to Figure 4 and Figure 5 . As shown in Figure 3As shown in FIG, one end of the pole 9 is provided with a stepped base, which includes a high step 91 and a low step 92. Figure 5 As shown in the figure, a through hole 1031 is provided in the middle of the flexible connector body 103, and the shape of the through hole 1031 is consistent with the outer shape of the high step 91. During assembly, the flexible connector with the pole lug 11 welded thereto is sleeved on the pole 9 from top to bottom until the lower surface of the flexible connector body 103 contacts the upper surface of the low step 92, and the through hole 1031 matches the high step 91. After the sleeve connection, the flexible connector 10 is welded to the step surface 921 of the low step to achieve the fixation of the two. Laser welding is preferably used. The position of the laser welding area 102 is as shown in FIG. Figure 6 As shown in .

[0052] S3. Put the sealing ring on the pole, and put the first plastic part on the sealing ring.

[0053] like Figure 7 or Figure 8 As shown, the sealing ring 8 is in the shape of a stepped sleeve, which is mounted on the pole 9 from the top downward, and the bottom plane of the sealing ring 8 contacts the step surface 911 of the high step of the pole 9. After the sealing ring 8 is mounted, the first plastic part 6 is mounted. The bottom surface of the first plastic part 6 protrudes upward to form a hollow boss, and a hole is provided in the middle of the boss for the pole 9 to pass through. The inner diameter of the hole matches the maximum outer diameter of the sealing ring 8, or the inner diameter of the hole is larger than the maximum outer diameter of the sealing ring 8. The bottom of the boss is a hollow structure for accommodating the soft connection body 103 and the stepped base. The soft connection body 103 and the stepped base are embedded in the boss, as shown in FIG. Figure 7 As shown in .

[0054] S4. Install the insulating film 5, the top cover 4, the insulating ceramic 3, the second plastic part 2 and the conductive block 1 around the pole 9 in order from top to bottom; wherein the insulating film 5 is clamped between the first plastic part 6 and the top cover 4.

[0055] Specifically, the insulating film 5 is provided with a hole for the first plastic part 6 to pass through, such as Figure 2 As shown in , during assembly, the hole on the insulating film 5 is just covered by the periphery of the boss of the first plastic part 6. At the same time, the top cover sheet 4 is also provided with a boss similar to the first plastic part 6, so that the insulating film 5 can be flatly pressed between the first plastic part 6 and the top cover sheet 4, thereby fixing the insulating film 5. No additional connection method is required to fix it with the first plastic part 6, eliminating the hot melt process in the prior art, simplifying the structure of the first plastic part 6, reducing the height of the first plastic part 6, saving assembly time, and making the battery cell structure more compact.

[0056] S5. Rivet the terminal and conductive block together to complete the final seal. Before riveting, all components need to be pressed tightly to achieve better fastening and sealing effects, prevent battery leakage, and ensure battery power stability.

[0057] S6, bending the tab, wrapping the core in the insulating film. Initially, in order to weld the tab 11 and the pole 9, the two cores 7 are separated, after welding and riveting are completed, the tab 11 is bent, the two cores 7 are aligned, the insulating film 5 fixed at the top of the cover plate is folded and wrapped down, the core 7 is wrapped in the insulating film 5 as a whole, the preliminary assembly is completed, and subsequent processes can be carried out according to the existing mature assembly method, for example, the core after the preliminary assembly is placed in an aluminum shell. The state of the core 7 after the preliminary wrapping is shown in FIG. 6. Figure 9

[0058] Preferably, the thickness of the soft connection 10 is consistent with the thickness of the high-step 91 in the stepped base, so that the soft connection 10 is located between the base of the pole 9 and the first plastic part 6 after assembly, eliminating the occupation of the space of the shell in the thickness direction of the cover plate by the soft connection 10, making the battery structure more compact, and improving the overall energy density of the core 7.

[0059] The embodiment of the application also provides a square lithium ion battery prepared by using the square lithium ion battery preparation method. The square lithium ion battery comprises a core 7, a cover plate and an insulating film 5. In the embodiment of the application, the cover plate of the battery is not assembled before the preparation of the battery, and the assembly of the cover plate is completed in the preparation process of the core. The cover plate comprises a pole 9 and a first plastic part 6, a top cover sheet 4, a second plastic part 2 and a conductive block 1 which are sequentially sleeved on the pole 9, and a sealing ring 8 is further arranged between the first plastic part 6 and the pole 9. The insulating ceramic 3 is arranged in the top cover sheet 4, and the insulating film 5 is clamped between the first plastic part 6 and the top cover sheet 4. The arrangement order and position of the insulating film 5 are as described above. The pole 9 is connected to the core 7 through a soft connection 10, and the insulating film 5 covers the core 7. The pole 9 is provided with a stepped base, the soft connection 10 is provided with a through hole 1031 through which the pole 9 passes, the soft connection 10 is welded on the step face 921 of the low-step of the stepped base, the thickness of the soft connection 10 is consistent with the thickness of the high-step 91 of the stepped base, and the conductive block 1 is riveted to the pole 9.

[0060] Preferably, the soft connection 10 comprises a soft connection main body 103 and a tab clamping part 104 located at both ends of the soft connection main body 103. The soft connection main body 103 is provided with a through hole 1031 which is matched with the high-step 91 of the stepped base. The tab clamping part 104 is used for clamping the tab 11 connected to the core 7, and the tab 11 can be inserted into the tab clamping part 104.

[0061] ​Preferably, the bottom surface of the first plastic part 6 protrudes upward to form a hollow boss, a hole is formed in the middle of the boss for the pole 9 to pass through, the soft connection body 103 and the stepped base are embedded in the boss, and the lower part of the boss is used to accommodate the soft connection body 103 and the stepped base. Preferably, the thickness of the soft connection 10 is consistent with the thickness of the high step 91. This design can save the height of a soft connection 10 in the thickness direction of the cover plate, making the battery structure more compact and improving the energy density of the battery.

[0062] Preferably, the soft connection 10 is welded with the tab 11 by ultrasonic welding, the low step 92 of the stepped base is welded with the soft connection 10 by laser welding, and the positions of the ultrasonic welding area 101 and the laser welding area 102 are as shown in Figure 6

[0063] The present application adopts a split structure cover plate, which is assembled during the preparation of the battery cell. During the preparation process, the soft connection is sleeved between the pole and the first plastic part by setting an intermediate hole on the soft connection, which reduces the space occupation of the soft connection in the thickness direction of the cover plate, effectively reduces the thickness of the cover plate, and further improves the energy density of the battery. In addition, the cover plate is assembled during the preparation of the battery cell, without using a pre-assembled cover plate. During the assembly process, the insulating film can be directly placed between the top cover sheet and the first plastic part by sleeving, and is tightly fixed, avoiding the hot melting process in the prior art, simplifying the assembly process, saving manpower and resources, and improving the assembly efficiency. In addition, since the first plastic part does not need to reserve a structure for hot melting, the structure of the first plastic part is simplified, the height of the first plastic part is reduced, the space occupation of the battery cell in the height direction is further reduced, the effective volume of the core inside the battery cell is increased under the premise that the specification and model of the battery cell remain unchanged, and the energy density of the battery is further increased.

[0064] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for preparing a square lithium-ion battery, characterized in that: include: S1. Weld the flexible connector to the tab on the matched winding core; S2. Sleeve the flexible connector onto the pole, and weld the flexible connector onto the step surface of the lower step of the pole; Wherein, the pole comprises a stepped base, and the stepped base comprises the lower step and the upper step; S3, putting the sealing ring on the pole, and putting the first plastic part on the sealing ring; S4. Installing an insulating film, a top cover sheet, an insulating ceramic, a second plastic component, and a conductive block around the pole in order from top to bottom; wherein the insulating film is directly placed between the first plastic component and the top cover sheet by means of a sleeve connection and is pressed and fixed; S5, riveting the pole and the conductive block; S6, bending the tabs and wrapping the winding core in the insulating film; Wherein, the thickness of the flexible connection is consistent with the thickness of the high step; The bottom surface of the first plastic part protrudes upward to form a hollow boss, a hole for the pole to pass through is defined in the middle of the boss, and the flexible connection body and the stepped base are embedded in the boss.

2. The method for preparing a square lithium-ion battery according to claim 1, wherein: The flexible connection includes a flexible connection body and tab clamping portions located at both ends of the flexible connection body; a through hole is provided in the middle of the flexible connection body to match the high-position step.

3. The method for preparing a square lithium-ion battery according to claim 2, wherein: Step S1 includes: S11, inserting the tab connected to the winding core into the tab clamping portion; S12, welding the tab to the tab clamping portion by ultrasonic welding.

4. The method for preparing a square lithium-ion battery according to claim 1, wherein: In step S2, the flexible connection is welded to the step surface of the low step by laser welding.

5. A square lithium-ion battery, characterized in that: The square lithium-ion battery is prepared using the preparation method of any one of claims 1 to 4; the square lithium-ion battery includes a winding core, a cover plate, and an insulating film; the cover plate includes a pole and a first plastic part, a top cover sheet, a second plastic part, and a conductive block that are sequentially sleeved on the pole, and a sealing ring is also provided between the first plastic part and the pole; insulating ceramic is provided in the top cover sheet, and the insulating film is clamped between the first plastic part and the top cover sheet; the pole is connected to the winding core through a flexible connection, and the insulating film is covered on the outside of the winding core; a stepped base is provided on the pole, and a through hole for the pole to pass through is provided on the flexible connection, and the flexible connection is welded to the step surface of the lower step in the stepped base, and the thickness of the flexible connection is consistent with the thickness of the higher step in the stepped base; the conductive block is riveted to the pole.

6. The square lithium-ion battery according to claim 5, wherein: The flexible connection includes a flexible connection body and tab clamping parts located at both ends of the flexible connection body; the through hole is opened on the flexible connection body, and the through hole matches the high step of the stepped base; the tab clamping part is used to clamp the tab connected to the winding core.

7. The square lithium-ion battery according to claim 5, wherein: The flexible connection is welded to the tab by ultrasonic welding, and the low step of the stepped base is welded to the flexible connection by laser welding.

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