Soft package ion battery tab and matched top seal head slotting design method

Abstract

The invention discloses a soft package ion battery tab and a matched top seal head slotting design method, and relates to the technical field of battery tabs, the soft package ion battery tab comprises a metal conductive substrate, the edges of the two sides of the metal conductive substrate are respectively provided with chamfered edges, and chamfers alpha are formed between the chamfered edges and the surface of the substrate; the outer side of the metal conductive substrate is provided with a PP adhesive layer, the beveled edge and the PP adhesive layer form a sealing interface in gradual transition, and the pp adhesive layer extends from two ends of the metal conductive substrate to form outer edges; an aluminum plastic film is arranged outside the PP adhesive layer; according to the invention, by adjusting the angle size of the tab beveled edge and matching with the slotting design of the top seal head, the problem of top seal liquid leakage of the soft package battery and the problem of insulation caused by excessive top seal melt glue can be effectively solved; the optimization of the tab beveling structure is matched with a new end socket structure, so that the thickness of the tab base body can be increased, and a feasible scheme is provided for improving the overcurrent capability of the tab in the later period.

Description

Technical Field

[0001] This invention relates to the field of battery tab technology, and in particular to a design method for slotting tabs and matching top seals of a soft-pack ion battery. Background Technology

[0002] The tabs are thin, conductive metal sheets extending from the positive and negative current collectors inside a lithium-ion battery cell; they serve as the contact points for charging and discharging.

[0003] The cross-section of the existing technology corresponding to the 0.5mm thick tab structure, top seal head slot design, and encapsulation effect is as follows: Figure 1 The existing top-sealing slotted design mainly aims to meet two requirements: 1. No leakage from the battery cell; 2. Good insulation performance. However... Figure 2 In the encapsulation process, the required positions within frame a need to be filled with a large amount of PP adhesive. The source of this adhesive requires a large amount of melting of the tab adhesive and the PP layer of the aluminum-plastic film. As the amount of melting increases, accumulation occurs on both sides of the end cap, which in turn affects the insulation performance of the battery cell. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a design method for slotting the tabs and matching top seals of a soft-pack lithium battery, which solves the problem of leakage caused by fluctuations in the position of the top seal slots and the molten adhesive during the battery tab encapsulation process.

[0005] Technical solution:

[0006] A soft-pack ion battery tab, comprising:

[0007] A conductive metal substrate, wherein chamfered edges are provided on both sides of the conductive metal substrate at their respective edges, and a chamfered angle α is formed between the chamfered edges and the surface of the substrate.

[0008] The outer side of the conductive metal substrate is provided with a PP adhesive layer, the chamfer and the PP adhesive layer form a gradually transitioning sealing interface, and the PP adhesive layer extends outward at both ends of the conductive metal substrate.

[0009] An aluminum-plastic film is provided on the outside of the PP adhesive layer.

[0010] Preferably, the chamfer α is 8° to 15°, and the thickness of the chamfer is 0.10 mm to 0.15 mm.

[0011] Preferably, the conductive metal substrate is made of aluminum or nickel-plated copper.

[0012] Preferably, the inner width of the electrode tab is equal to the total width of the electrode tab base - ((electrode tab base thickness - outer thickness) / tanα).

[0013] A method for designing a slotted top seal for an electrode tab, used in any of the above-described pouch-type lithium-ion battery electrode tabs, includes the following steps:

[0014] 1) The outermost edge of the conductive metal substrate is a first step, and a second step is formed at the conductive edge of the conductive metal substrate.

[0015] The width W1 of the first step matches the inner width W0 of the tab, W0=W–(H–t1) / tanα, where W is the total width of the metal substrate and H is the thickness of the metal substrate;

[0016] 2) The depth of the first step d1 = (T × k1 + H) / 2, where T is the total thickness of the tab adhesive and k1 is the residual rate of the tab adhesive;

[0017] 3) The depth of the second step, d2, is (T×k2) / 2, where k2 is the adhesive residue rate of the second step;

[0018] 4) The bevel width of the first step is W2 = W0 + 2 × (d1 – d2) / tanβ, where β is the auxiliary angle of the bevel of the end cap, and β is less than α.

[0019] As a preferred embodiment, the limiting thickness = aluminum-plastic film thickness * 2 - (aluminum-plastic film PP thickness * 2 * (1 - aluminum-plastic film residual rate)), and the tab sealing thickness = first step depth * 2 + limiting thickness.

[0020] Preferably, the residual rate of the tab adhesive and the aluminum-plastic film is 85-92%.

[0021] Preferably, the residual PP adhesive in the second step is 95-100%.

[0022] Preferably, the auxiliary angle of the beveled end cap is 1 to 5 degrees smaller than the chamfer, and β is a fixed angle.

[0023] Beneficial effects: By adjusting the angle and size of the tab bevel, and in conjunction with the slotted design of the top seal head, the problem of leakage from the top seal of soft-pack batteries and the insulation problem caused by excessive top seal adhesive can be effectively solved; the optimized tab bevel structure, combined with the new head structure, can make the thickness of the tab substrate thicker and thicker, providing a feasible solution for improving the overcurrent capacity of the tab in the later stage. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the electrode structure in the prior art;

[0025] Figure 2 This is a schematic diagram of the cross-section of the top-sealing package in the prior art;

[0026] Figure 3 This is a schematic diagram of the cross-sectional structure of the battery tab of the present invention;

[0027] Figure 4 This is a schematic diagram of the battery tab structure of the present invention;

[0028] Figure 5 This is a schematic diagram of the cross-sectional structure of the chamfered edge of the present invention;

[0029] Figure 6 This is a schematic diagram of the external structure of the present invention.

[0030] Reference numerals: 1. Conductive metal substrate; 2. Beveling; 3. PP adhesive layer; 5. Outer edge; 6. Aluminum-plastic film; 7. First step; 8. Second step. Detailed Implementation

[0031] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example

[0033] A type of tab for a soft-pack ion battery, the tab being composed of a metal conductive substrate 1, a chamfered edge 2, a PP adhesive layer 3, and an outer edge 5.

[0034] like Figure 3 The conductive metal substrate 1 is a flat strip with a chamfered edge 2 on each of its two long sides. The chamfered edge 2 forms a continuous slope with the substrate surface, turning the originally sharp metal edge into a "bevel" shape.

[0035] The PP adhesive layer 3 is coated on the upper and lower surfaces of the metal conductive substrate 1 by hot melting, and a gradient sealing interface parallel to the bevel is formed in the beveled edge area; this interface can be seamlessly connected with the aluminum-plastic film PP layer during subsequent heat sealing to avoid local glue shortage or accumulation.

[0036] The outer edge 5 is a "flash" of PP adhesive layer 3 extending outward from both ends of the metal conductive substrate 1. During the top sealing stage, it is clamped by aluminum-plastic film 6 to form a sealing chain of three layers of "metal-adhesive-film" melting simultaneously, further blocking the electrolyte leakage channel.

[0037] Furthermore, an aluminum-plastic film 6 is provided on the outside of the PP adhesive layer 3.

[0038] The aluminum-plastic film is folded six times to form a cavity that accommodates the battery cell, and the tabs extend from the edge of the cavity.

[0039] The inner PP layer of the aluminum-plastic film 6 is directly opposite the PP adhesive layer 3 of the tab. During heat sealing, the two soften and dissolve simultaneously. The beveled edge of the beveled edge 2 provides a guide for the molten PP, allowing the adhesive to climb along the bevel and form a "wedge-shaped sealing ring".

[0040] The sealing ring has a gradually transitioning thickness at the metal-film interface, eliminating dead angles and reducing the risk of cracking due to stress concentration.

[0041] See Figures 4-6 The working face of the end cap is provided with a first step 7, a second step 8, and an inclined opening 9:

[0042] The first step 7 is used to accommodate the electrode body, and its plane matches the width of the inner side of the electrode, limiting the left and right displacement of the electrode.

[0043] The second step 8 has a reduced depth and is used to press the chamfered area 2, so that the PP glue in this area melts and fills the chamfered gap under low pressure.

[0044] The bevel 9 connects the first step 7 and the second step 8 to form a "figure-eight" guide surface. During heat sealing, the molten adhesive is squeezed by the bevel 9 towards the root of the chamfered edge 2, preventing the adhesive from overflowing disorderly into the inside of the battery cell.

[0045] This double-step-bevel combination structure enables the sealing process to proceed in a three-stage sequence: "first positioning, then local softening, and finally overall compaction," thereby improving the consistency of the sealing process.

[0046] A chamfer α is formed between the chamfer 2 and the surface of the substrate 1. While keeping the chamfer 2 angle unchanged, the thickness of the conductive metal substrate 1 can be increased to 0.8 mm, 1.0 mm, or even 1.2 mm.

[0047] The length of the chamfered edge 2 is extended proportionally with the thickness, and the PP adhesive layer 3 is thickened or kept at the original thickness. Only the depth of the first step 7 needs to be increased accordingly to continue to obtain the same gradient sealing interface.

[0048] The thickened metal substrate 1 has an increased cross-sectional area, improving current carrying capacity without reducing sealing reliability, achieving a synergistic design of "thick tabs - high current - no glue overflow".

[0049] Bevel 2 is not limited to a straight bevel; it can also be a concave arc, a convex arc, or a stepped bevel.

[0050] The concave chamfer can form a "glue pool" during heat sealing, storing more molten PP to compensate for thickness fluctuations in the aluminum-plastic film.

[0051] The convex arc chamfer can reduce the initial contact area and reduce the pressure resistance of the end cap, making it suitable for ultra-thin aluminum-plastic film encapsulation;

[0052] The stepped slope decomposes the single chamfer into two angle segments, corresponding to the second step 8 and the bevel 9 respectively, making the melt flow path segmented and controllable, and further suppressing glue overflow.

[0053] The protruding end of the electrode metal conductive substrate 1 is extended and stamped into an "L" or "T" shape to directly form the protective plate connecting piece:

[0054] The chamfered edge 2 area remains within the angle range of this invention to ensure sealing performance;

[0055] The extended section requires no additional welding, reducing internal resistance;

[0056] An avoidance groove is provided in the extension area of ​​the end cap to avoid excessive compression of the protective plate connecting piece.

[0057] For special stacking processes, the chamfer 2 can be placed on the inner side of the metal conductive substrate 1 (closer to the cell side):

[0058] During heat sealing, the molten adhesive first fills the inner chamfer and then spreads to the outer aluminum-plastic film 6 to form an "inward wedge seal", which is suitable for packaging schemes where the tabs are bent towards the inside of the cell; the direction of the end cap step is reversed accordingly, and the rest of the principle is the same as the forward chamfer.

[0059] A method for slotting the top seal head of a soft-pack lithium battery electrode tab includes:

[0060] Step S1: Determine the width W1 of the first step

[0061] a. A tab for a soft-pack ion battery is provided, wherein the total width of the metal conductive substrate is W=22.00 mm, the thickness is H=0.50 mm, the chamfer thickness is t1=0.12 mm, and the chamfer is α=12°;

[0062] b. The width W1 of the first step matches the inner width W0 of the tab, where the inner width of the tab = total width of the tab base - ((tab base thickness - outer thickness) / tanα). The inner width W0 of the tab is calculated as: total width of the tab base - ((tab base thickness - outer thickness) / tanα).

[0063] W0 = W – (H – t1) / tanα = 22 – (0.50 – 0.12) / tan12° = 20.21 mm;

[0064] c. Set the width W1 of the first step of the end cap directly to the aforementioned W0 to complete the assignment of the lateral positioning dimension.

[0065] Step S2: Determine the depth d1 of the first step

[0066] a. The total thickness of the tab adhesive is measured to be T = 0.20 mm;

[0067] b. Residual rate is mainly used to describe the percentage of the thickness of PP glue remaining after melting relative to the total thickness of PP. The residual rate of tab glue and aluminum-plastic film is generally controlled between 85% and 92%, and the residual rate of tab glue is selected as k1=0.90 within the range.

[0068] c. Calculate the depth of the first step: Depth of the first step = (Total thickness of tab adhesive * Residual tab adhesive + Thickness of tab substrate) / 2, i.e.

[0069] d1 = (T × k1 + H) / 2 = (0.20 × 0.90 + 0.50) / 2 = 0.340 mm.

[0070] Step S3: Determine the depth d2 of the second step

[0071] a. The residual PP adhesive rate in the second step is generally controlled within the range of 95% to 100%, and the residual PP adhesive rate in the second step is selected as k2=0.98;

[0072] b. Calculate the depth of the second step: (total thickness of the tab adhesive * residual adhesive rate of the second step) / 2, i.e.

[0073] d2 = (T × k2) / 2 = (0.20 × 0.98) / 2 = 0.098 mm.

[0074] Step S4: Determine the width W2 of the first step slope.

[0075] a. Angle β is generally 1~5 smaller than angle α, which is a fixed design value. Angle α is the chamfer angle, and angle β is the first step inclination angle. β is set to a fixed value that is 3° smaller than chamfer α, i.e. β=9°.

[0076] b. Calculate the width of the first step bevel: Width of the first step bevel = Width of the inner side of the tab + (Depth of the first step - Depth of the second step) / tanβ * 2, i.e.

[0077] W2 = W0 + 2 × (d1 – d2) / tanβ = 20.21 + 2 × (0.340 – 0.098) / tan9° =23.26 mm.

[0078] Step S5: Calculate the limiting thickness and the edge sealing thickness of the electrode lugs.

[0079] a. Provide aluminum-plastic film with a total thickness of 0.152 mm and a single-sided PP layer thickness of 0.052 mm, and select an aluminum-plastic film residual rate of 90%;

[0080] b. Calculate the limiting thickness: Limiting thickness = aluminum-plastic film thickness * 2 - (aluminum-plastic film PP thickness * 2 * (1 - aluminum-plastic film residual rate)).

[0081] Limiting thickness = 2 × 0.152 – 2 × 0.052 × (1 – 0.90) = 0.294 mm;

[0082] c. Calculate the edge sealing thickness of the electrode lug: Edge sealing thickness of electrode lug = Depth of the first step * 2 + Limiting thickness

[0083] Edge sealing thickness of the tab = 2 × d1 + limiting thickness = 2 × 0.340 + 0.294 = 0.974 mm.

[0084] Step S6: Machining and verifying the end cap

[0085] a. SKD61 steel is selected and vacuum hardened to HRC 52-54. A stepped grinding + precision electrical discharge combined process is used to form a bevel with β=9° in one go, with an angle error ≤±0.3°.

[0086] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A tab for a soft-pack ion battery, characterized in that, include: A conductive metal substrate, wherein chamfered edges are provided on both sides of the conductive metal substrate at their respective edges, and a chamfered angle α is formed between the chamfered edges and the surface of the substrate. The outer side of the conductive metal substrate is provided with a PP adhesive layer, the chamfer and the PP adhesive layer form a gradually transitioning sealing interface, and the PP adhesive layer extends outward at both ends of the conductive metal substrate. An aluminum-plastic film is provided on the outside of the PP adhesive layer.

2. The tab of a soft-pack ion battery according to claim 1, characterized in that, The chamfer α is 8° to 15°, and the thickness of the chamfer is 0.10 mm to 0.15 mm.

3. The tab of a soft-pack ion battery according to claim 2, characterized in that, The conductive metal substrate is made of aluminum or nickel-plated copper.

4. The tab of a soft-pack ion battery according to claim 2, characterized in that, Inner width of the tab = Total width of the tab base - ((Tab base thickness - Outer thickness) / tanα).

5. A method for designing a slotted top seal head for a tab, characterized in that, A tab for a soft-pack ion battery according to any one of claims 1-4, comprising the following steps: 1) The outermost edge of the conductive metal substrate is a first step, and a second step is formed at the conductive edge of the conductive metal substrate. The width W1 of the first step matches the inner width W0 of the tab, W0=W–(H–t1) / tanα, where W is the total width of the metal substrate and H is the thickness of the metal substrate; 2) The depth of the first step d1 = (T × k1 + H) / 2, where T is the total thickness of the tab adhesive and k1 is the residual rate of the tab adhesive; 3) The depth of the second step, d2, is (T×k2) / 2, where k2 is the adhesive residue rate of the second step; 4) The width of the inclined opening of the first step is W2 = W0 + 2 × (d1 – d2) / tanβ, where β is the inclination angle of the first step and β is less than α.

6. The method for slotting the top seal head of the electrode ear according to claim 5, characterized in that, Limiting thickness = aluminum-plastic film thickness * 2 - (aluminum-plastic film PP thickness * 2 * (1 - aluminum-plastic film residual rate)), tab sealing thickness = first step depth * 2 + limiting thickness.

7. The method for slotting the top seal head of the electrode ear according to claim 5, characterized in that, The residual rate of the tab adhesive and the aluminum-plastic film is 85-92%.

8. The method for slotting the top seal head of the electrode ear according to claim 5, characterized in that, The residual PP adhesive in the second step is 95-100%.

9. The method for slotting the top seal head of the electrode ear according to claim 5, characterized in that, The auxiliary angle of the beveled end cap is 1 to 5 degrees smaller than the chamfer, and β is a fixed angle.

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