Pouch-type lithium ion battery

Abstract

The utility model relates to the field of lithium ion battery preparation discloses a kind of soft package lithium ion batteries, including aluminium plastic film shell, the electrolyte of the electric core body encapsulated in the aluminium plastic film shell, electric core body includes tab, each tab is respectively compounded with tab rubber, each tab is respectively from the encapsulation edge of aluminium plastic film shell tab lead-out lead-out, in the encapsulation edge, there is the encapsulation sealing area of sealed tab by heat sealing, corresponding to the lead-out position of each tab, recess is opened on the edge profile of the encapsulation sealing area of tab, tab is respectively arranged in recess, tab rubber and aluminium plastic film shell are heat-sealed and sealed connection in the inner surface in the range of the encapsulation sealing area of tab, the edge of the encapsulation sealing area of tab includes the profile of recess.The technical scheme improves the structure of tab encapsulation edge, fundamentally avoids tab rubber to be pressed and protrude, to release the internal space of battery, improve energy density, while guaranteeing sealing reliability and insulation safety.

Description

Technical Field

[0001] This utility model relates to the field of lithium-ion battery technology, specifically to a soft-pack lithium-ion battery. Background Technology

[0002] Soft-pack lithium-ion batteries are packaged in aluminum-plastic film. The tabs are sealed to the edge of the package through heat sealing to achieve lead-out and sealing. To prevent the tabs from bending and contacting the aluminum layer of the aluminum-plastic film, which could cause a short circuit, the tab adhesive laminated on the tabs is usually wider than the package width.

[0003] During the research of this invention, the inventors discovered that this results in the tab adhesive protruding 0.5-2mm from the aluminum-plastic film plane on both sides of the encapsulation area after packaging. This protrusion requires space to be reserved when the battery cell is installed in the casing, forcing a corresponding reduction in the size of the battery cell itself, thus limiting the improvement of battery energy density. With the increasing demands for battery capacity in electronic products, how to eliminate this wasted space while ensuring safety and sealing has become an urgent technical problem to be solved. Summary of the Invention

[0004] One of the objectives of this utility model is to provide a soft-pack lithium-ion battery. This technical solution improves the structure of the tab packaging edge, fundamentally preventing the tab adhesive from bulging under pressure, thereby releasing internal space of the battery, increasing energy density, and ensuring sealing reliability and insulation safety.

[0005] This utility model provides a soft-pack lithium-ion battery, including an aluminum-plastic film shell, a cell body encapsulated within the aluminum-plastic film shell, and an electrolyte. The cell body includes tabs, each tab being coated with tab adhesive, and each tab extending from the encapsulation edge of the aluminum-plastic film shell. At the edge of the package, a sealing area is formed by heat sealing to seal the electrode tabs, characterized in that: Corresponding to the lead-out position of each of the aforementioned tabs, a notch recessed towards the center of the battery is formed on the edge contour of the encapsulation sealing area of ​​the tab. The tabs are respectively disposed at the notches, and the tab adhesive is heat-sealed to the inner surface of the aluminum-plastic film shell within the sealing area of ​​the tab. The edge of the sealing area of ​​the tab includes the outline of the notch.

[0006] Optionally, the width of the widest part of the notch is greater than the width of the corresponding tab.

[0007] Optionally, the notch is an arc-shaped notch, a U-shaped notch, or a V-shaped notch.

[0008] Optionally, the depth of the notch is denoted as H_notch. Let T_tab be the thickness of each tab and the tab adhesive thereon. There is T_tab ≤ H_notch ≤ 2.5 * T_tab.

[0009] Optionally, the depth of the notch is 1.2 to 1.8 times the thickness of the tab together with the tab adhesive.

[0010] Optionally, the notch is an arc-shaped notch.

[0011] Optionally, the tab adhesive does not protrude beyond the edge of the aluminum-plastic film in the encapsulation sealing area.

[0012] Optionally, the battery cell body is a wound battery cell or a stacked battery cell.

[0013] Optionally, the electrolyte is a liquid electrolyte or a solid electrolyte.

[0014] Optionally, the edge of the battery cell body, which is not provided with the tabs on the encapsulation edge of the aluminum-plastic film shell, is folded up outside the side of the thickness of the aluminum-plastic film shell.

[0015] As can be seen from the above, by adopting the technical solution of this embodiment, a notch is provided on the edge contour of the aluminum-plastic film shell at the lead-out position of each tab, providing space for the tab to extend. This actively avoids the tab adhesive being squeezed and protruding outside the edge of the aluminum-plastic film during packaging, completely eliminating the occupation of internal space by the tab adhesive protrusion. Thus, the electrode length can be increased without changing the external dimensions of the battery, directly improving the battery capacity and energy density.

[0016] In addition, using the technical solution of this embodiment, a notch is provided only on the edge contour of the aluminum-plastic film of the aluminum-plastic film shell to allow the electrode tab to extend. In the design, on the basis of ensuring that the sealing area and sealing uniformity requirements of the electrode tab extension position meet the sealing reliability requirements, the parameters of the notch design (including but not limited to shape, depth and width) are combined with the notch clearance function to ensure sealing reliability.

[0017] In addition, by adopting the notch setting scheme of this embodiment, the stress bending point of the tab is guided to the inside of the encapsulation sealing area, so that it is far away from the aluminum layer of the aluminum-plastic film when bending, which helps to reduce the risk of short circuit.

[0018] Furthermore, this invention can be implemented simply by modifying the aluminum-plastic film punching die, making it easy to promote and implement. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, do not constitute an undue limitation of the present invention.

[0020] Figure 1 This is a schematic diagram of the front view structure of a prior art soft-pack lithium-ion battery. Figure 2 This is a three-dimensional structural diagram of a prior art soft-pack lithium-ion battery; Figure 3 This is a schematic diagram of the front view structure of a soft-pack lithium-ion battery provided in an embodiment of the present utility model; Figure 4 , 5 These are front and rear perspective three-dimensional structural diagrams of the soft-pack lithium-ion battery provided in the embodiments of this utility model; Figure 6 This is a schematic diagram of the main structure of another soft-pack lithium-ion battery provided in an embodiment of the present invention; Figure 7 , 8 These are front and rear perspective three-dimensional structural diagrams of another soft-pack lithium-ion battery provided in this embodiment of the present utility model.

[0021] Figure label: 1: Aluminum-plastic film housing; 11: Encapsulation edge leading out from the tab; 12: The package edge does not have a tab leading out; 13: Notch; 2: Electrode; 3: Electrode adhesive. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0023] Examples of embodiments of the present invention are shown in the accompanying drawings in a detailed description below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0024] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0025] Furthermore, the terms "" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0027] See Figures 3-8 As shown.

[0028] This embodiment provides a soft-pack lithium-ion battery, including an aluminum-plastic film casing 1, a cell body encapsulated within the aluminum-plastic film casing 1, and an electrolyte.

[0029] The electrolyte is an ion-conducting medium, which can be either a liquid electrolyte or a solid electrolyte. When a liquid electrolyte is used, it is immersed in the cell body; when a solid electrolyte is used, it can exist as one or more layers between the positive and negative electrodes and the separator. It can be either a liquid electrolyte or a solid electrolyte.

[0030] The battery cell body includes a positive tab and a negative tab (hereinafter referred to as tab 2). The battery cell body can be a wound structure or a stacked structure. In the wound structure, a positive electrode sheet, a separator, and a negative electrode sheet are wound to form a columnar body with a layered structure, and its tab 2 is composed of metal strips led out from the positive and negative electrode sheets respectively. In the stacked structure, multiple positive electrode sheets, negative electrode sheets, and separators are alternately stacked to form a layered stacked structure, and its tab 2 is composed of metal strips led out from multiple positive and negative electrode sheets connected in parallel.

[0031] The tab 2 extends from the encapsulation edge 11 of the aluminum-plastic film housing 1, and tab adhesive 3 is laminated on both the front and back of each tab 2.

[0032] The aluminum-plastic film housing 1 is heat-sealed to form a packaging edge 11 with tabs and a packaging edge 12 without tabs. On the packaging edge 12 without tabs, the opposing surfaces (referred to as the inner surfaces) of the upper and lower aluminum-plastic films are fully bonded together under the action of heat and pressure, and then sealed after cooling. The battery cell body and electrolyte are sealed inside the aluminum-plastic film housing 1.

[0033] The core improvement of this utility model lies in the structure of the encapsulation edge 11 with tabs. A notch 13 is pre-processed at the outer edge of the encapsulation edge 11 with tabs on the aluminum-plastic film shell 1 by a punching die. This notch 13 is a contour defect formed by a recess from the original edge line of the aluminum-plastic film inward (i.e. towards the cell body inside the battery).

[0034] For each tab 2, at the position where each tab 2 is led out, a notch 13 is formed on the outer edge contour of the encapsulation edge 11 with the tab leading out, which is recessed toward the center of the battery. For example, when the tab 2 extends from the top width end of the battery, a notch 13 is formed on the top edge contour of the encapsulation edge 11 with the tab leading out, and the notch 13 is oriented upward. The tab 2 is set at the notch 13, that is, it extends out of the notch 13 to the top.

[0035] During preparation, a notch 13 is pre-cut into the edge contour of each tab 2 at the corresponding position of the upper and lower aluminum-plastic films that constitute the aluminum-plastic film shell 1 using a custom mold. After the battery cell body is placed in the battery cell receiving cavity on the lower aluminum-plastic film, the upper aluminum-plastic film is covered over the battery cell receiving cavity. The notches 13 on the upper and lower aluminum-plastic films are opposite each other, and each tab 2 extends out from the position of the notch 13.

[0036] When heat-sealing the edge of the aluminum-plastic film with tab 2 extending out, the heat-sealed mating surface covers the entire sealing edge and the surfaces of the upper and lower aluminum-plastic films that are in contact with each other. Tab 2 extends out from between the upper and lower aluminum-plastic films and extends out of the aluminum-plastic film from the position of notch 13.

[0037] During heat sealing, in the area where tab 2 protrudes, under the action of heat and pressure, the adhesive layer on the inner surface of the upper and lower aluminum-plastic films that are in contact with the tab 3 is fully bonded together by heat fusion; in other areas where the inner surfaces of the upper and lower aluminum-plastic films that are not led out by tab 2 are directly in contact, the adhesive layer on the inner surface is fully bonded together by heat fusion. Under pressure, cooling and sealing are performed to form a heat-sealed edge.

[0038] Thus, at the protruding end of the battery's tab 2, a continuous, reliable, and sealed strip-shaped area, i.e., the encapsulation sealing area, is formed with its outer edge encompassing the outline of notch 13. The outline of notch 13 constitutes the recessed portion of the outer edge of this encapsulation sealing area. Tab 2 protrudes from the encapsulation sealing area; specifically, tab 2 protrudes from the encapsulation sealing area at the location of notch 13. After encapsulation, the top of the tab adhesive 3 is substantially flush with the end face of the outer edge of the aluminum-plastic film housing 1, without protruding.

[0039] The arrangement of the tabs 2 and the notches 13 may include, as shown in the figure, two tabs 2 on the same side corresponding to two notches 13, or tabs 2 on both sides corresponding to notches 13 on both sides.

[0040] As can be seen from the above, by adopting the technical solution of this embodiment, by providing a notch 13 on the edge contour of the aluminum-plastic film shell 1 at the lead-out position of each tab 2, space is provided for the extension of the tab 2. This actively avoids the tab adhesive 3 being squeezed and protruding outside the edge of the aluminum-plastic film during packaging, and completely eliminates the occupation of internal space by the protrusion of the tab adhesive 3. Thus, the length of the electrode sheet can be increased without changing the external dimensions of the battery, directly improving the battery capacity and energy density.

[0041] In addition, using the technical solution of this embodiment, a notch 13 is provided only on the edge contour of the aluminum-plastic film of the aluminum-plastic film housing 1 to allow the tab 2 to extend. In the design, on the basis of ensuring that the sealing area and sealing uniformity of the tab 2 extension position meet the sealing reliability requirements, the parameters of the notch 13 (including but not limited to shape, depth and width) are designed in conjunction with the clearance function of the notch 13 to ensure sealing reliability.

[0042] Furthermore, by adopting the notch 13 scheme of this embodiment, the bending point of the tab 2 is guided to the inside of the encapsulation sealing area, so that it is far away from the aluminum layer of the aluminum-plastic film when bending, which helps to reduce the risk of short circuit.

[0043] Furthermore, this invention can be implemented simply by modifying the aluminum-plastic film punching die, making it easy to promote and implement.

[0044] like Figure 1 As shown, the protruding height of the tab 3 in the traditional structure occupies the internal space of the battery.

[0045] See Figure 2 As shown, the structure of this embodiment eliminates this space occupation. Therefore, without changing the total thickness of the battery exterior, this space can be redistributed to the cell body. Specifically, the length of the electrode plates (positive or negative) can be increased, thereby improving the battery's capacity and energy density.

[0046] As an illustration of this embodiment, the packaging edge 12 of the aluminum-plastic film shell 1 without the tabs 2 can be further folded up along the edge of the cell body to the outside of the thickness of the aluminum-plastic film shell 1 to form a compact battery pack. The folding method can adopt existing technology and processes in the field.

[0047] The implementation and effects of this utility model will be further described in detail below with reference to the embodiments.

[0048] Example 1: This example uses a soft-pack lithium-ion battery.

[0049] The present invention relates to a soft-pack lithium-ion battery, comprising an aluminum-plastic film casing 1, a wound cell body, and a liquid electrolyte. The front and back sides of the two tabs 2 of the cell body are respectively coated with tab adhesive 3, and the two tabs 2 are led out from the top of the encapsulation edge 11 with tabs, and a safe electrical distance is separated between the two tabs 2.

[0050] For each tab 2, corresponding to the lead-out position of tab 22, two arc-shaped notches 13 are punched out. The two notches 13 are recessed towards the center of the battery interior. The two tabs 2 extend out of the aluminum-plastic film shell 1 from the two notches 135 respectively.

[0051] During heat sealing, the directly adhered aluminum-plastic film layers are heat-sealed together. At the lead-out positions of the two tabs 2, the tab adhesive 3 on the two tabs 2 is heat-sealed to the inner surface layer of the aluminum-plastic film shell 1, forming a continuous encapsulation sealing area on the top of the battery. The top edge of this encapsulation sealing area includes the outline of an arc-shaped notch 135. After encapsulation, the top of the tab adhesive 3 is flush with the top edge of the aluminum-plastic film, without any protrusions.

[0052] The thickness T_tab of each tab 2, together with the tab adhesive 3 on its two surfaces, is 0.3 mm, and the width of each tab 2 (excluding the width of the tab adhesive 3) is 4 mm. The depth H_notch of notch 13 is designed to be 0.45mm (1.5 * T_tab), and the width of notch 13 is designed to be 5mm.

[0053] Comparative example: a battery with a traditional structure.

[0054] See Figure 1 , 2 It uses the same battery structure as the traditional one, and its tab adhesive 3 protrudes about 1.0mm from the aluminum-plastic film plane after encapsulation.

[0055] All other conditions (cell type, active material, electrolyte, external dimensions, etc.) are exactly the same as in Example 1.

[0056] Number of samples per group: 25.

[0057] The battery samples of Example 1 and the comparative example are compared and tested according to the table below:

[0058] Energy density improvement effect Measure the battery volume and calculate the volumetric energy density (Wh / L). 450 Wh / L 485 Wh / L Energy density is increased by approximately 7.8%. This demonstrates that the present invention significantly improves energy density by eliminating wasted space. Sealing reliability verification Helium mass spectrometry leak detection method, judgment criterion: leak rate ≤ 0.05 Pa·cm³ / s 0.02 Pa·cm³ / s 0.01 Pa·cm³ / s Superior sealing performance. Surprisingly, the sealing performance of this invention was not worsened by the presence of notch 13, but rather improved. This proves that the optimized notch 13 design allows the tab adhesive 3 to be subjected to more uniform force and to fuse more fully with the aluminum-plastic film, breaking the technical prejudice that "notch 13 will weaken the seal". Insulation safety verification After bending tab 2 90 degrees in different directions, a 1500VAC / 60s withstand voltage test was performed. Pass rate: 92% (23 / 25) 100% pass rate (25 / 25) Safety is significantly improved. Traditional structures have a short-circuit risk. The notch 13 of this invention naturally guides the bending point of the tab 2 towards the inside of the battery, away from the aluminum layer, fundamentally solving the short-circuit hazard under extreme bending. This is an unexpected safety advantage. Mechanical strength verification Measure the peel force (N / 15mm) of the encapsulated sealing area. 6.8 N / 15mm 7.1 N / 15mm The mechanical seal strength is comparable and slightly superior. The notch 13 design of this invention does not weaken the sealing interface bonding force, eliminating any concerns about the mechanical strength of this structure. Long-term cycle life test Capacity retention after 500 cycles of 1C charge-discharge. 88.5% 90.2% Superior cycle performance. Due to the more ample internal space and lower cell expansion stress, this invention exhibits superior long-term cycle stability.

[0059] As can be seen from the above, the recessed notch 13 provides space for the tab 2, eliminating the space occupied by the protrusion of the tab adhesive 3. With the same external dimensions, the length of the electrode sheet can be increased, directly improving the battery capacity and energy density (by 7.8%).

[0060] By adopting the solution of this embodiment, the size of notch 13 (the ratio of H_notch to T_tab) is optimized. While providing room for maneuver, it ensures that the encapsulation sealing area still has sufficient effective sealing area and uniform force, resulting in high sealing reliability (lower leakage rate and 100% pass rate in withstand pressure test).

[0061] By adopting the solution of this embodiment, the potential bending point of the tab 2 is also guided to the inside of the battery, reducing the risk of short circuit. This utility model solution breaks the technical prejudice that "the tab adhesive 3 must be raised to ensure sealing". Through a simple, non-obvious structure, it simultaneously solves the contradiction between energy density and sealing safety, achieving unexpected technical effects.

[0062] The above experimental data fully demonstrates that by setting a notch 13 on the packaging edge 11 with tabs, this utility model unexpectedly achieves the dual excellent effects of "significantly improving energy density" and "enhancing safety sealing", successfully solving the traditional technical problem that has long plagued this field.

[0063] In the process of researching this utility model, the inventors also conducted research on the design of the notch 13. Some experimental data are selected below as illustrations.

[0064] Experimental Sample Preparation 1: Reference cell: All experimental groups and comparative examples used the same model and batch of wound cell body, with tab 2 (including tab adhesive 3) thickness T_tab = 0.3 mm and tab 2 width W_tab = 4.0 mm.

[0065] Variable control: Only the design parameters of the notch 13 on the top sealing edge of the aluminum-plastic film shell 1 were changed to prepare the following 7 groups of samples, with 25 samples in each group.

[0066] Experimental Group A: Arc-shaped notch 13. Depth H_notch = 0.45 mm (1.5 * T_tab), width W_notch = 5.0 mm (>W_tab).

[0067] Experimental Group B: Arc-shaped notch 13. Depth H_notch = 0.30 mm (1.0 * T_tab), width W_notch = 5.0 mm.

[0068] Experimental group C: Arc-shaped notch 13. Depth H_notch = 0.75 mm (2.5 * T_tab), width W_notch = 5.0 mm.

[0069] Experimental group D: Arc-shaped notch 13. Depth H_notch = 0.45 mm, width W_notch = 4.0 mm (= W_tab).

[0070] Experimental group E: U-shaped notch 13. Depth H_notch = 0.45 mm, opening width W_notch = 5.0 mm.

[0071] Experimental group F: V-shaped notch 13. Depth H_notch = 0.45 mm, opening width W_notch = 5.0 mm.

[0072] Comparative example G (e.g.) Figure 1 (As shown): No notch 13, tab adhesive 3 protrudes about 1.0 mm after encapsulation.

[0073] The above experimental samples were tested according to the table below: A Arc shape, H=1.5T, W>W_tab 485 0.01 7.1 100%(25 / 25) ★★★★★ Optimal B Arc shape, H=1.0T, W>W_tab 455 0.02 6.9 100% ★★Limited improvement in energy density and mediocre sealing. Tab 2 is still under pressure, and the protrusion has not been completely eliminated. C Arc shape, H=2.5T, W>W_tab 487 0.08 (Unacceptable) 5.8 100% ★Seal failure. The excessive depth of notch 13 severely eroded the effective sealing area, significantly reduced peel strength, and resulted in leakage rates exceeding the standard in most samples. D Arc shape, H=1.5T, W=W_tab 484 0.03 6.2 92% (23 / 25) ★★Safety risks exist. Insufficient width causes the edge of tab 2 to be too close to the sealing boundary, which can easily lead to the tab adhesive 3 peeling off from the aluminum-plastic film or short circuit when bent. E U-shaped, H=1.5T, W>W_tab 483 0.02 6.5 100% ★★★ Good, but not optimal. The stress is relatively concentrated at the corner of the U-shaped bottom, and the peel strength and sealing performance are slightly inferior to those of the curved shape. F V-shaped, H=1.5T, W>W_tab 482 0.04 6.0 96% (24 / 25) ★★ Poor. The V-shaped tip has a high concentration of stress, which can easily become a weak point in the seal, increasing the leakage rate. It is also prone to cracking at the tip when bent. G 13 without gaps, with protrusions 450 0.02 6.8 92% (23 / 25) ★★★Benchmark performance.

[0074] Experimental Sample Preparation 2: Reference Cell: All experimental groups and comparative examples used the same model and batch of laminated cell bodies. To ensure comparability, a cell with a tab 2 (including tab adhesive 3 on both surfaces) thickness T_tab = 0.25 mm and tab 2 width W_tab = 3.5 mm was selected. The relevant parameter values ​​of tab 2 were selected as representative parameters based on statistical measurements of multiple mainstream laminated cell products in the industry.

[0075] Variable control: Only the design parameters of the notch 13 on the top sealing edge of the aluminum-plastic film shell 1 were changed to prepare the following 7 groups of samples, with 25 samples in each group.

[0076] Experimental Group A: Arc-shaped notch 13. Depth H_notch = 0.38mm (≈1.5 * T_tab), width W_notch = 4.5 mm (>W_tab).

[0077] Experimental Group B: Arc-shaped notch 13. Depth H_notch = 0.25 mm (1.0 * T_tab), width W_notch = 4.5 mm.

[0078] Experimental group C: Arc-shaped notch 13. Depth H_notch = 0.63 mm (≈2.5 * T_tab), width W_notch = 4.5 mm.

[0079] Experimental group D: Arc-shaped notch 13. Depth H_notch = 0.38 mm, width W_notch = 3.5 mm (= W_tab).

[0080] Experimental group E: U-shaped notch 13. Depth H_notch = 0.38 mm, opening width W_notch = 4.5 mm.

[0081] Experimental group F: V-shaped notch 13. Depth H_notch = 0.38 mm, opening width W_notch = 4.5 mm.

[0082] Comparative example G: such as Figure 1 , 2 As shown, the notch 13 protrudes about 0.8 mm after the tab adhesive 3 is encapsulated.

[0083] The above experimental samples were tested according to the table below: A Arc shape, H=1.5T, W>W_tab 513 0.01 6.9 100% (25 / 25) ★★★★★ Optimal B Arc shape, H=1.0T, W>W_tab 488 0.02 6.8 100% ★★Limited improvement in energy density. Slight compression exists on tab 2, and the protrusion has not been completely eliminated. C Arc shape, H=2.5T, W>W_tab 514 0.07 (Unacceptable) 5.6 100% ★Seal failure. The excessive depth of notch 13 severely erodes the effective sealing area, significantly reduces peel strength, and results in excessive leakage. D Arc shape, H=1.5T, W=W_tab 510 0.04 6.0 88% (22 / 25) ★★Safety risks exist. Insufficient width results in insufficient edge sealing allowance, which can easily lead to the tab adhesive 3 peeling off from the aluminum-plastic film or short circuit when bending. E U-shaped, H=1.5T, W>W_tab 509 0.02 6.3 100% ★★★ Good, but not optimal. The stress is relatively concentrated at the corner of the U-shaped bottom, and the peel strength is slightly inferior to that of the curved shape. F V-shaped, H=1.5T, W>W_tab 508 0.05 5.8 92% (23 / 25) ★★ Poor. The V-shaped tip has a high stress concentration, which is a weak point in the seal, leading to increased leakage and poor reliability. G 13 without gaps, with protrusions 475 0.02 6.7 90% (22 / 25) ★★★Benchmark performance.

[0084] As can be seen from the experimental data above, the inventors conducted experiments using both stacked and wound battery cells. The experimental trends of the two types of cells were highly consistent and equally unexpected, proving that the technical solution provided by this utility model has universality.

[0085] Experiments have shown that, compared with V-shaped and U-shaped notches, the arc-shaped notch 13, with its smooth transition contour, can effectively avoid stress concentration, making the sealing pressure and heat distribution more uniform, thus achieving the best sealing strength (highest peel force) and reliability (lowest leakage rate).

[0086] Furthermore, the experimental data above shows a complex and nonlinear interaction between the depth, width, and shape of notch 13. Simply creating a notch 13 (as in groups B, C, and D) does not consistently achieve optimal results; instead, it may lead to seal failure (group C) or safety risks (group D). Optimal results are achieved when the depth, width, and shape simultaneously satisfy a specific, narrow optimal range, as in group A. The optimal parameters (arc shape, H_notch=(1.2~1.8)*T_tab, W_notch>W_tab) produce a synergistic effect, simultaneously achieving a comprehensive breakthrough in the three core indicators: maximum energy density improvement, optimal seal reliability, and 100% insulation safety. This is an unexpected effect where "1+1+1>3".

[0087] Furthermore, the applicant needs to clarify that there is a contradiction in traditional understanding between "increasing energy density" (eliminating protrusions) and "ensuring sealing safety" (as shown by the failure of group C). However, this utility model successfully breaks this technical paradox through a specific notch 13 design, achieving superior sealing and safety performance while increasing energy density, which far exceeds the reasonable expectations of those skilled in the art.

[0088] The embodiments described above do not constitute a limitation on the scope of protection of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the above embodiments should be included within the scope of protection of this technical solution.

Claims

1. A soft-pack lithium-ion battery, comprising an aluminum-plastic film casing, a cell body encapsulated within the aluminum-plastic film casing, and an electrolyte, wherein the cell body includes tabs, each tab being coated with tab adhesive, and each tab extending from an encapsulation edge extending from the tabs of the aluminum-plastic film casing. At the edge of the package, a sealing area is formed by heat sealing to seal the electrode tabs, characterized in that: Corresponding to the lead-out position of each of the aforementioned tabs, a notch recessed towards the center of the battery is formed on the edge contour of the encapsulation sealing area of ​​the tab. The tabs are respectively disposed at the notches, and the tab adhesive is heat-sealed to the inner surface of the aluminum-plastic film shell within the sealing area of ​​the tab. The edge of the sealing area of ​​the tab includes the outline of the notch.

2. The soft-pack lithium-ion battery according to claim 1, characterized in that: The width of the widest part of the notch is greater than the width of the corresponding tab.

3. The soft-pack lithium-ion battery according to claim 2, characterized in that: The notch is an arc-shaped notch, a U-shaped notch, or a V-shaped notch.

4. The soft-pack lithium-ion battery according to claim 2, characterized in that: Let the depth of the notch be H_notch. Let T_tab be the thickness of each tab and the tab adhesive thereon. There is T_tab ≤ H_notch ≤ 2.5* T_tab.

5. The soft-pack lithium-ion battery according to claim 4, characterized in that: The depth of the notch is 1.2 to 1.8 times the thickness of the tab and the tab adhesive.

6. The soft-pack lithium-ion battery according to claim 5, characterized in that: The notch is an arc-shaped notch.

7. The soft-pack lithium-ion battery according to claim 2, characterized in that: The tab adhesive does not protrude beyond the edge of the aluminum-plastic film in the encapsulation sealing area.

8. The soft-pack lithium-ion battery according to claim 1, characterized in that: The battery cell body is a wound battery cell or a stacked battery cell.

9. The soft-pack lithium-ion battery according to claim 1, characterized in that: The electrolyte is a liquid electrolyte or a solid electrolyte.

10. The soft-pack lithium-ion battery according to claim 1, characterized in that: The edge of the battery cell body, which is not provided with the tabs on the encapsulation edge of the aluminum-plastic film shell, is folded up outside the side of the thickness of the aluminum-plastic film shell.

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