Battery without tab welding and preparation method

Abstract

The present invention provides a battery without tab welding and a method for manufacturing the battery. The battery comprises a housing and a cell consisting of a positive electrode sheet, a negative electrode sheet, and a separator. The bottom of the housing is provided with a raised welding groove, which is embedded in the exposed positive and negative current collectors. The positive and negative current collectors are then laser-welded to the housing at the thinnest point of the raised welding groove. By improving and optimizing the bottom of the battery housing and the top cover of the battery cover, which are in direct contact with the positive and negative current collectors, the present invention increases the contact area and reliability of the two. Furthermore, direct welding enhances the welding effect between the two, thus having high practical value.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and in particular to a battery without tab welding and a preparation method thereof. Background Art

[0002] With the current market demand for batteries rapidly increasing, the requirements for batteries are also becoming increasingly higher. To meet market demand, major manufacturers are constantly redesigning and improving batteries by improving battery energy density, reducing battery costs, and enhancing the battery's high-current charge and discharge capabilities. The most common and mainstream design is to use "tab-less" or "full-tab" batteries. One of these designs increases the internal space of the battery and increases capacity by directly contacting or directly welding the positive and negative current collectors with the battery casing, abandoning the welding method of positive and negative current collectors - "cover plate" (current collector plate) - battery casing. Although this method increases the internal space of the battery and improves energy, the close contact method and direct welding method have some structural and technical shortcomings. First, no matter how tight the contact between the positive and negative current collectors and the battery shell is, there will still be gaps. At the same time, during use, due to the complexity of battery usage, the generation of such gaps will continue to increase, resulting in unstable battery internal resistance and large losses in battery power output and input, affecting the battery's fast charging, high-current discharge and service life; second, there is no problem in directly welding the positive and negative current collectors and the battery shell. In essence, however, in actual use, it is affected by the thickness of the material at the welding point of the battery shell. The thicker the thickness, the worse the welding effect, and it may even cause cold welding or failure to weld, resulting in unstable battery internal resistance.

[0003] In response to the above problems, how to ensure the reliable welding of the positive and negative electrode current collectors and the battery shell is the main improvement direction of this project. Summary of the Invention

[0004] The present invention provides a battery without tab welding and a preparation method thereof, which improves upon the direct welding of positive and negative electrode current collectors and battery shells, optimizes welding effects, and reduces welding internal resistance.

[0005] A battery without tab welding comprises a shell and a battery core consisting of a positive electrode sheet, a negative electrode sheet and a separator. A raised welding groove is provided at the bottom of the shell, which is embedded in the exposed positive and negative electrode collectors. The positive and negative electrode collectors are laser welded to the shell at the thinnest part of the raised welding groove.

[0006] Preferably, the housing includes a main shell (battery shell) with an opening at the top and a connecting shell (battery cover) mechanically sealed to the top opening of the main shell, and the main shell (battery shell) is cylindrical or square; the connecting shell (battery cover) includes at least one metal part and one insulating part.

[0007] The raised welding grooves are punched toward the positive and negative electrode current collectors.

[0008] The raised weld groove is not punched through, and the thinnest thickness of the raised weld groove is controlled at 0-0.2mm. When welding the positive and negative electrode current collectors to the outer shell, a certain pressure is first applied to ensure that the positive and negative electrode current collectors are fully in contact with the bottom of the battery shell or the top cover of the battery cover, while allowing the raised groove to be directly embedded in the exposed positive and negative electrode current collectors. Then, the thinnest part of the raised groove is directly welded with a laser to ensure a tight weld between the two.

[0009] The raised welding groove is punched through, and the thinnest thickness of the raised welding groove is controlled to be 0mm. Then, a metal material that is the same as or fused with the positive and negative current collectors is placed at the breakdown point. The metal material placed at the positive terminal includes but is not limited to aluminum, aluminum alloy, tin, etc.; the metal material placed at the negative terminal includes but is not limited to copper, copper alloy, nickel, nickel alloy, tin, etc. When welding the positive and negative current collectors to the outer shell, a certain pressure is first applied to ensure that the positive and negative current collectors are in full contact with the bottom of the battery shell or the top cover of the battery cover, while allowing the raised welding groove to be directly embedded in the exposed positive and negative current collectors. Then, the metal material is placed at the position for direct laser welding, so that the two are tightly welded without any gaps.

[0010] Preferably, a metal or alloy filament is provided at the punching portion of the raised welding groove, and laser welding is performed directly at the position where the metal or alloy filament is placed, so that the positive and negative current collectors are tightly welded to the shell without leakage.

[0011] The positive and negative electrode sheets each include a coating area and a blank area, with the edges of the blank area extending beyond the edges of the separator. The blank areas (blank areas) of the positive and negative electrode sheets are in direct contact with the top covers of the main housing (battery case) and the connecting housing (battery cover), respectively.

[0012] As described above, the height of the stamped raised welding groove cannot be higher than the blank width of the corresponding positive and negative electrode collectors to prevent battery short circuit during the manufacturing process.

[0013] Preferably, the number and arrangement shape of the raised welding grooves can be controlled by oneself, and the shape and number of the raised welding grooves can be flexibly set according to actual needs to form a welding groove with multiple contact points and strong structure.

[0014] The preparation method of the battery without tab welding comprises the following steps:

[0015] (a) On a metal foil, an active material is coated on the metal foil according to the positive and negative electrode process ratios, and after cutting, a positive electrode sheet and a negative electrode sheet with a blank area formed on one side are obtained;

[0016] (b) stacking the separator, the positive electrode sheet, and the negative electrode sheet in sequence to form a winding core by winding or stacking, with the ends of the positive and negative electrode sheets having the blank areas being positioned outside the two long sides of the separator, respectively, and the blank areas extending beyond the outer edges of the separator;

[0017] (c) Pre-processing the outer shell so that the portion facing the positive and negative electrode current collectors is punched with a raised welding groove to form a welding groove;

[0018] (d) Place the coiled core in the outer shell, apply pressure to fully contact the positive and negative current collectors with the outer shell, and directly embed the protruding welding grooves into the exposed positive and negative current collectors. Then, directly laser weld the protruding grooves to ensure a tight connection between the two.

[0019] (e) The battery is sealed, and the electrolyte is injected into the liquid injection port through vacuum pumping and then sealed. After the production is completed, the battery is subjected to the formation and capacity separation processes to obtain a tab-free battery.

[0020] The number of the raised welding grooves is set to be several.

[0021] The beneficial effects of the present invention are as follows: the present invention increases the contact area and reliability of the battery shell bottom and the battery cover top that are in direct contact with the positive and negative electrode current collectors by improving and optimizing the two, and at the same time enhances the welding effect between the two by direct welding, which has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description 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.

[0023] Figure 1 This is a schematic side cross-sectional view of the present invention in which the convex groove is not directly punched through;

[0024] Figure 2 This is a schematic diagram of the structure of the convex groove directly punched through the present invention;

[0025] Figure 3 3a-3f are shape diagrams of the convex groove arrangement and welding effect of the present invention;

[0026] Figure 4 Schematic diagram of the positive and negative electrode structures in the embodiment of the present invention;

[0027] Figure 5 2 is a schematic diagram of the winding core structure in an embodiment of the present invention;

[0028] Figure 6 2. This is a schematic diagram of the structure of a tab-free battery in an embodiment of the present invention;

[0029] Figure 7 It is a schematic diagram of the structure of a non-welded tab-free battery in the comparative example of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing a tab-free welded battery comprises the following steps:

[0033] (a) Preparation of cylindrical 32650 tab-free batteries. On a metal foil, the active material is coated on the foil according to the positive and negative electrode process ratio to form a coating area 402. After cutting, the positive electrode sheet 501 and the negative electrode sheet 503 are respectively formed with a blank area 401 on one side. The blank width of the positive and negative electrodes is 4±0.5 mm. Figure 4 ;

[0034] (b) The separator 502 and the positive and negative electrodes are stacked in sequence and then wound or stacked to form a winding core 500, including a positive terminal 504 and a negative terminal 505, and the ends of the positive and negative electrodes with blank spaces are placed outside the two long sides of the separator, and the blank space 401 exceeds the outside of the edge of the separator 502. Figure 5 ;

[0035] (c) Pre-processing the main shell (battery shell) to punch the raised welding groove 100 on the part facing the positive and negative electrode current collectors 102 ( Figure 1 ), take the bottom center of the battery shell as the standard, and punch four equal parts at 3mm away from the bottom center. Figure 3 a-shaped solder groove ( Figure 3 The two horizontal lines in a are wire grooves formed by connecting several adjacent protrusions. The protrusions are very small. The welding groove specification is 2mm wide * 10mm long (error +0.05mm).

[0036] Because there is a hollow in the middle of the core ( Figure 3 The middle dotted circle), so when setting the raised welding groove, avoid the middle part, you can follow Figure 3 3a-3f diagram settings;

[0037] (d) The height of the highest point of the weld groove is 2.0 ± 0.1 mm (the height of the highest point of the weld groove should be less than the width of the blank space between the positive and negative electrodes). The weld groove cannot be punched through. The thinnest thickness of the weld groove should be controlled at 0.1 mm ± 0.05 mm to form a raised weld groove.

[0038] (e) Place the core in the main shell (battery shell), use a certain pressure to fully contact the positive and negative electrode current collectors with the bottom of the battery shell, and at the same time make the protruding welding groove 100 directly embedded in the exposed positive and negative electrode current collectors, and then directly use laser welding to weld the protruding groove to make the two tightly welded. Figure 6 6a;

[0039] (f) Place the connecting shell (battery cover) on the opening side of the main shell (battery case), apply a certain pressure to fully contact the battery cover with the positive electrode current collector, and then weld the two tightly using laser welding, and then seal the battery;

[0040] (g) Vacuum the liquid injection port, inject the electrolyte, and then seal it;

[0041] (h) After the production is completed, the tab-free battery is obtained through processes such as formation and capacity separation.

[0042] Example 2

[0043] A method for preparing a tab-free welded battery comprises the following steps:

[0044] (a) Preparation of cylindrical 32650 tab-free batteries. On a metal foil, the active material is coated on the foil according to the positive and negative electrode process ratio to form a coating area 402. After cutting, the positive electrode sheet 501 and the negative electrode sheet 503 are respectively formed with a blank area 401 on one side. The blank width of the positive and negative electrodes is 4±0.5 mm. Figure 4 ;

[0045] (b) The separator 502 and the positive and negative electrodes are stacked in sequence to form a winding core by winding or stacking, and the ends of the positive and negative electrodes with blank spaces are placed outside the two long sides of the separator, and the blank space 401 exceeds the outside of the edge of the separator 502. Figure 5 ;

[0046] (c) The main shell (battery shell) is pre-processed to punch a raised welding groove 100 on the part facing the positive and negative electrode current collectors. The raised welding groove 100 is punched ... Figure 3 a-shaped solder groove ( Figure 3 The two horizontal lines in a are wire grooves formed by connecting several adjacent protrusions. The protrusions are very small. The welding groove specification is 2mm wide * 10mm long (error +0.05mm).

[0047] Because there is a hollow in the middle of the core ( Figure 3 The middle dotted circle), so when setting the raised welding groove, avoid the middle part, you can follow Figure 3 a-3f graphic settings;

[0048] (d) The highest point height of the welding groove is 2.0±0.1mm (the highest point height of the welding groove should be less than the blank width of the positive and negative electrodes), and the welding groove is punched through ( Figure 2 ), the thinnest thickness of the solder groove is controlled at 0mm to form a raised solder groove; at the same time, a nickel-plated copper wire (metal wire 101) is embedded in the raised solder groove 100, and the specification of the nickel-plated copper wire is 2mm wide * 10mm long (error -0.5mm);

[0049] (e) Place the coil in the main housing (battery case), apply pressure to fully contact the positive and negative electrode current collectors with the bottom of the battery case, and at the same time, allow the protruding welding grooves 100 to be directly embedded in the exposed positive and negative electrode current collectors. Then, directly laser weld the nickel-plated copper wire embedded in the protruding grooves to ensure that the two are tightly welded. Figure 6 6b;

[0050] (f) Place the connecting shell (battery cover) on the opening side of the main shell (battery case), apply a certain pressure to fully contact the battery cover with the positive electrode current collector, and then weld the two tightly using laser welding, and then seal the battery;

[0051] (g) Vacuum the liquid injection port, inject the electrolyte, and then seal it;

[0052] (h) After the production is completed, the tab-free battery is obtained through processes such as formation and capacity separation.

[0053] Comparative Example 1

[0054] A method for preparing a tab without welding, comprising the following steps:

[0055] 1. Prepare cylindrical 32650 tab-free batteries. On the metal foil, apply the active material according to the positive and negative electrode process ratio. After cutting, the positive and negative electrodes are formed into blank sheets on one side, and the blank width of the positive and negative electrodes is 4±0.5mm. Figure 4 ;

[0056] 2. After stacking the separator and the positive and negative electrodes in sequence, they are wound or stacked to form a core, and the ends of the positive and negative electrodes with blanks are placed on the outside of the two long sides of the separator, and the blanks exceed the outside of the separator edge. Figure 5 ;

[0057] 3. Place the core in the main shell (battery shell), and use a certain amount of pressure to fully contact the positive and negative electrode current collectors of the raised welding groove with the bottom of the battery shell. Figure 7 ;

[0058] 4. Inject electrolyte into the main housing;

[0059] 5. Place the connecting shell (battery cover) on the opening side of the main shell (battery shell), use a certain pressure to fully contact the battery cover with the positive electrode current collector, and then seal the battery;

[0060] 6. After the production is completed, the tab-free battery is obtained through processes such as formation and capacity separation.

[0061] The tab-free batteries prepared in Examples 1 and 2 and Comparative Example 1 were subjected to performance tests. The test results are shown in Table 1. The test methods were conventional methods in the art.

[0062] performance Example 1 Example 2 Comparative Example 1 Internal resistance / (mΩ) 4.2 4.5 Fluctuation within the range of 4.3-4.8 Contact Strong welding and close contact Strong welding and close contact No welding, contact with gaps

[0063] It can be seen from the above table that compared with the comparative example, the tab-free battery prepared according to the method described in the embodiment of the present invention has significantly stable internal resistance, and the electrode collector is firmly welded to the shell and has close contact, which ensures the stability of the battery performance.

[0064] 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 without tab welding, comprising a housing (10) and a battery cell consisting of a positive electrode sheet (501), a negative electrode sheet (503) and a separator (502), characterized in that: The bottom of the shell (10) is provided with a raised welding groove (100), which is embedded in the exposed positive and negative electrode current collectors (102). The positive and negative electrode current collectors are laser welded to the shell (10) at the thinnest part of the raised welding groove (100). The raised welding groove (100) is punched through, and the thinnest thickness of the raised welding groove (100) is controlled to be 0 mm. A metal wire (101) is provided at the punched part of the raised welding groove (100). During welding, laser welding is directly performed at the position where the metal wire (101) is placed, so that the positive and negative electrode current collectors (102) are tightly welded to the shell (10) without any leakage.

2. The battery without tab welding according to claim 1, characterized in that: The raised welding groove (100) is punched and arranged in the direction of the positive and negative electrode current collectors (102).

3. The battery without tab welding according to any one of claims 1-2, characterized in that: The positive electrode sheet (501) and the negative electrode sheet (503) both include a coating area (402) and a blank area (401), and the edge of the blank area (401) exceeds the edge of the separator (502).

4. The battery without tab welding according to claim 3, characterized in that: The height of the raised welding groove (100) cannot be higher than the width of the blank area (401).

5. The method for preparing a battery without tab welding according to claim 4, characterized in that: Here are the steps: (a) coating the active material on the metal foil according to the positive and negative electrode process ratio, and cutting the metal foil to obtain a positive electrode sheet (501) and a negative electrode sheet (503) with a blank area (401) formed on one side; (b) stacking the separator (502), the positive electrode sheet (501) and the negative electrode sheet (503) in sequence to form a roll core by winding or stacking, and placing one end of the positive and negative electrode sheets provided with the blank area (401) outside the two long sides of the separator (502), respectively, and the blank area exceeds the outside of the separator edge; (c) performing preliminary processing on the outer shell so that the portion thereof facing the positive and negative electrode current collectors is punched with a raised welding groove (100) to form a welding convex groove; (d) placing the winding core in the shell of the outer shell (10), applying a certain pressure to fully contact the positive and negative electrode current collectors (102) with the shell of the outer shell (10), and simultaneously embedding the protruding welding grooves (100) directly into the exposed positive and negative electrode current collectors (102), and then directly laser welding the protruding grooves to make the two tightly welded; (e) The battery is sealed, and the electrolyte is injected into the liquid injection port through vacuum pumping and then sealed. After the production is completed, the battery is subjected to the formation and capacity separation processes to obtain a tab-free battery.

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