Pouch-type lithium ion battery and electronic device

Abstract

The utility model relates to the field of battery manufacturing discloses a kind of soft package lithium ion battery and electronic equipment. Soft package lithium ion battery includes aluminium plastic film shell, the electrolyte of being encapsulated in the shell in the electric core, and the positive electrode tab of being connected with the positive electrode and the negative electrode of the electric core respectively from the width end of the aluminium plastic film shell, the aluminium plastic film shell includes the base film formed with accommodating cavity and the covering film covering the accommodating cavity opening;At least one length side of the aluminium plastic film shell is formed with heat seal edge, and the heat seal edge is formed by the edge of the covering film and the edge of the base film hot melt sealing combination;Each heat seal edge is folded to the side where the covering film is, and is tightly attached to the outer surface of the covering film. Application the technical scheme can significantly improve the sealing reliability of thin soft package battery, especially the same side tab battery, and make it better adapt to arc-shaped and other special-shaped design.

Description

Technical Field

[0001] This utility model relates to the field of battery manufacturing, and in particular to a soft-pack lithium-ion battery and electronic device. Background Technology

[0002] Lithium-ion batteries have become the core power source for portable electronic devices, electric vehicles, and energy storage systems due to their advantages such as high energy density, long cycle life, and no memory effect. Among them, soft-pack lithium-ion batteries using aluminum-plastic film as the outer shell are characterized by light weight, thinness, flexible shape design, and relatively good safety. They are especially suitable for consumer electronics products with stringent requirements for thickness and weight, such as ultra-thin smartphones, wearable devices, and foldable screen devices.

[0003] As electronic products increasingly pursue thinner, lighter designs and longer battery life, pouch lithium-ion batteries are also developing towards thinner profiles and higher energy density. Thin or even ultra-thin designs with a battery thickness of ≤3.0mm have become a mainstream requirement. However, reducing battery thickness poses a significant challenge to the reliability of the packaging process. Currently, the mainstream packaging process for soft-pack batteries involves placing the battery cell within a recess (receiving cavity) formed by stamping an aluminum-plastic film. The opening is then covered with a cover film (or another aluminum-plastic film). Finally, the edges of the cover film and the aluminum-plastic film at the edge of the recess (i.e., the base film edge) are fused and sealed using heat pressing, forming a heat-sealed edge. To protect this heat-sealed edge and ensure the battery's uniform appearance, the heat-sealed edge needs to be folded. In existing technologies, the standard folding method involves bending the heat-sealed edge towards the thicker side of the battery (i.e., the narrower side), and typically, the height after folding should not exceed the thickness of the battery body.

[0004] During the research process of this invention, the inventors discovered that the traditional side folding method has the following drawbacks when applied to thin batteries: To ensure reliable sealing, a sufficiently wide heat-sealed edge (i.e., sealing area) is desirable. However, when the battery thickness is extremely thin (e.g., ≤3.0mm), the physical space available for lateral bending is already very limited. Forcibly increasing the heat-sealed edge width not only makes the bending process difficult, easily causing wrinkles or internal stress leading to encapsulation failure, but also significantly increases the overall profile of the battery on the folded side, violating the size limitations of battery compartments in many electronic devices. Therefore, in actual production, the heat-sealed edge width of thin batteries is strictly limited, typically only 1-2mm, which directly restricts the improvement of sealing reliability and increases the risk of leakage.

[0005] The folded edge itself occupies a significant portion of the battery's width. Inside the battery, the cell's width must be smaller than the internal width of the aluminum-plastic film casing to allow sufficient margin for heat sealing and folding. In traditional designs, this margin must include the width of the heat-sealing edge and the curvature required for bending. For designs aiming for maximum energy density, this permanently occupied width by the folded edge structure directly reduces the width of the cell's active material, thus sacrificing battery capacity.

[0006] For batteries where the positive and negative tabs extend from the same width end, the width end opposite the tabs typically employs an integrated aluminum-plastic film connection to simplify the manufacturing process. In such batteries, both length sides of the heat-sealed edge require side folding, making the width design more significantly constrained by the aforementioned spatial limitations. Furthermore, for curved batteries designed to accommodate curved screens and other devices, regularly bending the heat-sealed edge along the complex curved side is extremely difficult, easily creating wrinkles and stress concentration points, leading to uneven encapsulation strength and becoming a weak point for seal failure.

[0007] To address these issues, the industry has attempted to optimize materials (such as developing more flexible aluminum-plastic films and stronger adhesives) or process parameters, but these are all marginal improvements and have failed to fundamentally resolve the physical space contradictions inherent in the structural design of folding the edges to the sides. Summary of the Invention

[0008] One of the objectives of this utility model embodiment is to provide a soft-pack lithium-ion battery and electronic device. Applying this technical solution can significantly improve the sealing reliability of thin soft-pack batteries, especially those with the same-side tab, and make them better adaptable to irregular designs such as curved shapes.

[0009] In a first aspect, this embodiment provides a soft-pack lithium-ion battery, comprising an aluminum-plastic film shell, a battery cell encapsulated within the shell, and an electrolyte. Positive and negative electrode tabs, connected to the positive and negative electrodes of the battery cell, extend from the wide end of the aluminum-plastic film shell. The aluminum-plastic film shell includes a base film forming a receiving cavity and a covering film covering the opening of the receiving cavity; A heat-sealed edge is formed on at least one length side of the aluminum-plastic film shell, the heat-sealed edge being formed by heat-sealing the edge of the cover film and the edge of the base film together; Each of the heat-sealed edges is folded toward the side where the covering film is located and is tightly attached to the outer surface of the covering film.

[0010] Optionally, the thickness of the pouch lithium-ion battery is less than or equal to 3.0 mm.

[0011] Optionally, the positive and negative electrode tabs extend from the same width end of the aluminum-plastic film shell. Furthermore, at the other width end of the aluminum-plastic film shell, the base film and the cover film are integrally connected.

[0012] Optionally, the heat-sealed edges are formed on both length sides of the aluminum-plastic film shell. Both heat-sealed edges are folded towards the side where the covering film is located and are tightly attached to the outer surface of the covering film.

[0013] Optionally, the widths of the two heat-sealed edges are configured such that they do not overlap each other when they are respectively in close contact with the outer surface of the cover film.

[0014] Optionally, the width of the heat-sealed edge is less than or equal to the width of the battery cell.

[0015] Optionally, the width of the heat-sealed edge is less than or equal to half the width of the battery cell.

[0016] Optionally, the width of the heat-sealed edge is greater than the thickness of the pouch lithium-ion battery.

[0017] Optionally, the battery cell and the battery body formed by the aluminum-plastic film shell are arc-shaped along the length direction.

[0018] Secondly, an electronic device provided by an embodiment of the present invention includes any of the soft-pack lithium-ion batteries described above.

[0019] As can be seen from the above, the soft-pack lithium-ion battery using the structure of this embodiment, because its heat-sealed edge on the length side is folded and tightly adhered to the outer surface of the cover film, allows for a wider heat-sealed edge, which is not limited by the battery thickness. This increases the sealing area, theoretically significantly reducing the risk of leakage and improving sealing reliability. Furthermore, compared to existing technologies where the heat-sealed edge is folded along the thickness direction of the battery and occupies the battery's width, the heat-sealed edge in this embodiment does not occupy the battery's width, providing a wider usable width for cell design and facilitating improvements in battery capacity and energy density. Attached Figure Description

[0020] The accompanying drawings, which are provided to further illustrate the present invention and form part of this application, do not constitute an undue limitation of the present invention.

[0021] Figure 1 , 2 A three-dimensional structural diagram of a soft-pack lithium-ion battery provided for an embodiment of this utility model; Figure 3 , 4 This is a three-dimensional structural diagram of another soft-pack lithium-ion battery provided in an embodiment of the present invention.

[0022] 1: Aluminum-plastic film outer shell; 11: Base film; 12: Covering film; 13: Receiving cavity; 21: Positive electrode; 22: Negative electrode; 3: Heat sealing the edges. Detailed Implementation

[0023] 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.

[0024] Examples of embodiments of the present invention described in detail below are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0025] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, but should not be construed as limiting the invention. In the description of the 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 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 invention.

[0026] Furthermore, the terms "first" 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 as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," 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 invention according to the specific circumstances.

[0028] See Figure 1-4 .

[0029] This embodiment provides a soft-pack lithium-ion battery, mainly comprising: an aluminum-plastic film shell 1, a battery cell (not shown in the figure), and an electrolyte (not shown in the figure). The aluminum-plastic film shell 1 is composed of an aluminum-plastic film, which includes a base film 11 and a cover film 12. The base film 11 is formed by stamping to create recesses (i.e., receiving cavities 13) for accommodating the battery cell, and the cover film 12 is a flat aluminum-plastic film sheet.

[0030] The battery cell is a lithium-ion battery cell with a stacked or wound structure, and has a positive electrode tab 21 and a negative electrode tab 22 that are respectively connected to the positive electrode and the negative electrode of the battery cell.

[0031] Electrolytes, as ion-conducting media, can be either liquid electrolytes or solid electrolytes.

[0032] In a soft-pack lithium-ion battery, the cell and electrolyte are housed in the cavity 13 of the base film 11 (aluminum-plastic film). The positive electrode tab 21 and the negative electrode tab 22 extend outward from the width edge of the cavity 13. The positive electrode tab 21 and the negative electrode tab 22 are respectively provided with tab adhesive on the front and back sides of the middle section of the aluminum-plastic film. During heat sealing, the tab adhesive on both surfaces is heat-sealed together with the inner surfaces of the base film 11 and the cover film 12 attached to their two surfaces. The ends of the positive electrode tab 21 and the negative electrode tab 22 extend out of the heat-sealed area and out of the aluminum-plastic film shell 1 for external connection.

[0033] A cover film 12 (aluminum-plastic film) covers the opening of the receiving cavity 13. The size of the cover film 12 is larger than the opening of the receiving cavity 13, so that the edge of the cover film 12 and the edge of the base film 11 form an overlapping area around the receiving cavity 13, so as to heat seal the overlapping area. In the heat-sealed area, the adhesive layer on the opposite surface of the overlapping cover film 12 and base film 11 is heat-melted and sealed together to seal the battery cell and electrolyte located in the receiving cavity inside the aluminum-plastic film shell 1.

[0034] In this embodiment, the heat-sealing edge 3 located on the long edge of the aluminum-plastic film shell 1 does not bend towards the thick side of the battery (i.e. the narrow side of the battery) as in the conventional design, but folds towards the side where the cover film 12 is located (i.e. the direction of a large surface of the battery), and finally adheres tightly to the outer surface of the cover film 12.

[0035] This invention avoids the sealing structure occupying space in the width and thickness directions of the battery body by directly folding and attaching the heat-sealing edge 3 to the outer surface of the cover film 12. This allows for the design of a wider heat-sealing edge 3 and a wider battery cell within the same battery dimensions.

[0036] The fabrication process of the soft-pack lithium-ion battery in this embodiment is as follows: Material preparation and punching: Provide aluminum-plastic film and punch to form a receiving cavity 13. For ease of description, the part after punching is referred to as the base film 11, and the flat outer part without punching is referred to as the cover film 12 (or a separate cover sheet is used).

[0037] Core loading and pre-sealing: The battery cell with the positive electrode tab 21 and negative electrode tab 22 welded together is placed into the receiving cavity 13 of the base film 11. The cover film 12 is aligned to cover the opening of the receiving cavity 13. The other three sides, except for the reserved liquid injection port, are heat-sealed for the first time (top seal and side seal) to form a preliminary encapsulation.

[0038] Electrolyte injection and final sealing: Electrolyte is injected through the injection port, and then the injection port is finally sealed.

[0039] Key folding process: After packaging, cut along the outer side of the heat-sealed edge 3 on the length side of the soft-pack lithium-ion battery (if necessary). Then, fold the heat-sealed edge 3 on this side towards the outer surface of the cover film 12 with its inner edge near the cell as the axis, and use a tool or light heat pressing to make it flat and tightly attached to the outer surface of the cover film 12.

[0040] As can be seen from the above, the soft-pack lithium-ion battery using the structure of this embodiment, because its heat-sealed edge 3 on the length side is folded and tightly adhered to the outer surface of the cover film 12, allows the width of the heat-sealed edge 3 to be unrestricted by the thickness of the battery, thus enabling the setting of a wider heat-sealed edge 3. This increases the sealing area, theoretically significantly reducing the risk of leakage and improving sealing reliability. Moreover, compared to the prior art scheme where the heat-sealed edge 3 is folded along the thickness direction of the battery and occupies the width dimension of the battery, the heat-sealed edge 3 of this embodiment does not occupy the width dimension of the battery, providing a wider usable width for cell design, which is beneficial to improving battery capacity and energy density.

[0041] The structure of this embodiment is particularly suitable for thin or ultra-thin batteries with a thickness of ≤3.0mm. At this thickness, the space constraints of traditional side folding are particularly prominent. By applying this invention, the width of the heat-sealed edge 3 is greater than the thickness of the soft-pack lithium-ion battery. The width of the heat-sealed edge 3 can be designed to be 3.5mm, 4.0mm or wider (for example, reaching 40%-50% of the cell width), thereby achieving a sealing area that is unattainable by traditional designs.

[0042] Furthermore, in traditional designs, to avoid interference from folded edges, the cell width must be significantly smaller than the inner width of the casing. However, the folding method of this invention eliminates the need to reserve lateral space for the folded edges, allowing the cell width to maximize the use of the casing's internal width. This directly increases the electrode coating area, thereby improving battery capacity and energy density within the same external dimensions. This ensures that improved battery sealing performance no longer comes at the expense of internal space in the width direction, achieving a synergistic optimization of sealing performance and energy density.

[0043] As an illustration of this embodiment, the positive electrode tab 21 and the negative electrode tab 22 extend from the same width end of the aluminum-plastic film shell 1. At the opposite width end, the base film 11 and the cover film 12 are integrally connected by the same aluminum-plastic film without heat sealing, forming an integral connection edge at this width end. This arrangement simplifies the packaging process of the aluminum-plastic film shell 1 and provides a robust and reliable mechanical connection point for the aluminum-plastic film shell 1.

[0044] In a pouch lithium-ion battery, the top sealing edge, at the wide end where the tab extends, forms heat-sealed edges 3 on both length sides of the battery. These heat-sealed edges 3 are folded and attached to the outer surface of the cover film 12. On the outer surface of the cover film 12, the edges of the two heat-sealed edges 3 face each other, either at a predetermined distance or directly opposite each other. Preferably, the width of each heat-sealed edge 3 is designed to be less than the overall width of the battery, ensuring that they do not overlap when flat against the outer surface of the cover film 12, thus guaranteeing a smooth appearance and uniform stress distribution for the pouch lithium-ion battery. In summary, the symmetrical double-long-side folding structure results in uniform stress distribution in the aluminum-plastic film shell 1 and good overall battery stability.

[0045] During the manufacturing process, in the punching stage, the position of the integral connecting edge at the wide end of the aluminum-plastic film shell 1 is planned to ensure that the electrode tabs extend from the opposite side. Correspondingly, before the folding process, the width of the heat-sealed edges 3 on both length sides is calculated or positioned using tooling to ensure that their projected positions on the outer surface of the cover film 12 do not overlap after folding. For example, when folding each heat-sealed edge 3, a heated arc-shaped pressure head can be used to smoothly transition and firmly attach the heat-sealed edges 3 to the outer surface of the cover film 12.

[0046] For example, in the case of thin batteries (e.g., 2.5mm thick), the width of the heat-sealed edge 3 on the length side is typically limited to less than 2.0mm using traditional designs. However, with this design, the width of each heat-sealed edge 3 can easily reach 3.5mm to 5.0mm or even wider. For instance, in a structure with heat-sealed edges 3 on both length sides, the width of each heat-sealed edge 3 can reach up to half the width of the battery cell. In summary, the structure of this embodiment perfectly adapts to the same-side tab design, and the symmetrical wide heat sealing and folding on both length sides solves the sealing reliability problem caused by the asymmetrical structure of this type of battery.

[0047] The following example, using the fabrication of a thin battery with a thickness of 2.5 mm, further illustrates the effect of this embodiment, wherein the tabs extend from the same width end of the battery. On the other width of the battery, the base film 11 and the cover film 12 are an integrated structure of a single aluminum-plastic film, with heat-sealed edges 3 formed on both length sides of the battery.

[0048] Control group: Using traditional technology, the heat-sealed edge 3 is folded to the thickness side of the battery, and the width of the heat-sealed edge 3 on the two length sides of the battery is 2.0mm.

[0049] Experimental group: Using the scheme of this embodiment, the width of the heat-sealed edge 3 on the two length sides of the battery is 4.0mm, and the two heat-sealed edges 3 are flipped and tightly attached to the outer surface of the battery cover film 12.

[0050] Helium leak testing was performed on battery samples from both the experimental and control groups to test their sealing performance. The results showed that the leakage rate of the experimental group was reduced by more than an order of magnitude compared to the control group. This demonstrates that the sealing reliability of the experimental group is more effective.

[0051] In addition, since the experimental group does not need to reserve width space for the thickness side folding edge, its effective cell width can be increased by about 3-4mm (based on the space originally planned to be occupied by the folding edge). Under the same length and thickness, the battery volume energy density is expected to be increased by 3%-5%.

[0052] As an illustration of this embodiment, the structure of this embodiment is also applicable to curved batteries. In a curved battery, the battery cell and the battery body after final aluminum-plastic film encapsulation are curved in the length direction to adapt to the curved surface structure of specific electronic devices. During manufacturing, a pre-formed curved tooling is used to heat-seal and fold the aluminum-plastic film to ensure that the aluminum-plastic film and the battery cell are in curved fit.

[0053] Traditional side-folding methods often result in complex three-dimensional bending at curved edges, making the process extremely difficult to control. However, the solution proposed in this invention simply requires attaching the heat-sealed edge 3 to the curved surface, simplifying the process and ensuring uniform stress distribution. This effectively addresses the industry pain point of low reliability in curved battery packaging.

[0054] In this embodiment, when the heat-sealed edge 3 is folded to the large surface (outer surface of the covering film 12), it only needs to be attached in one direction (towards the center of the curved surface or to adapt to the curved surface), which is easier to achieve in terms of process and can ensure the flatness and sealing integrity of the edge. The solution of folding the heat-sealed edge 3 to the outer surface of the covering film 12 in this utility model is particularly suitable for curved batteries.

[0055] In summary, compared to the traditional solution of bending the heat-sealed edge 3 towards the battery thickness side in the prior art, the heat-sealed edges 3 on each length side of this embodiment are folded and attached to the outer surface of the cover film 12, solving the three core contradictions described in the background art: overcoming the physical constraint that the width of the thin battery seal edge is limited by its thickness, thus significantly improving sealing reliability; freeing up the battery width direction space occupied by the traditional folding structure, providing a direct condition for improving energy density; and providing a friendly and reliable packaging solution for special battery structures such as same-side tabs and arc shapes, broadening design freedom. Therefore, this utility model is an innovative design that combines high reliability, high energy density, and high process adaptability.

[0056] The soft-pack lithium-ion battery of this embodiment is suitable for use as a power source in various electronic devices, such as smartphones, tablets, wearable devices (e.g., smartwatches, wristbands), Bluetooth headsets, and portable medical devices. Due to its high energy density and high sealing reliability, this battery is particularly suitable for compact electronic devices with stringent requirements regarding device thickness, battery life, and safety.

[0057] 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 battery cell encapsulated within the casing, and an electrolyte, wherein a positive electrode tab and a negative electrode tab connected to the positive and negative electrodes of the battery cell respectively extend from the wide end of the aluminum-plastic film casing, characterized in that, The aluminum-plastic film shell includes a base film forming a receiving cavity and a covering film covering the opening of the receiving cavity; A heat-sealed edge is formed on at least one length side of the aluminum-plastic film shell, the heat-sealed edge being formed by heat-sealing the edge of the cover film and the edge of the base film together; Each of the heat-sealed edges is folded toward the side where the covering film is located and is tightly attached to the outer surface of the covering film.

2. The soft-pack lithium-ion battery according to claim 1, characterized in that, The thickness of the soft-pack lithium-ion battery is less than or equal to 3.0 mm.

3. The soft-pack lithium-ion battery according to claim 1, characterized in that, The positive and negative electrode tabs extend from the same width end of the aluminum-plastic film shell. Furthermore, at the other width end of the aluminum-plastic film shell, the base film and the cover film are integrally connected.

4. The soft-pack lithium-ion battery according to claim 3, characterized in that, The heat-sealed edges are formed on both length sides of the aluminum-plastic film shell. Both heat-sealed edges are folded towards the side where the covering film is located and are tightly attached to the outer surface of the covering film.

5. The soft-pack lithium-ion battery according to claim 4, characterized in that, The widths of the two heat-sealed edges are configured such that they do not overlap each other when they are respectively in close contact with the outer surface of the cover film.

6. The soft-pack lithium-ion battery according to claim 5, characterized in that, The width of the heat-sealed edge is less than or equal to the width of the battery cell.

7. The soft-pack lithium-ion battery according to claim 6, characterized in that, The width of the heat-sealed edge is less than or equal to half the width of the battery cell.

8. The soft-pack lithium-ion battery according to any one of claims 1 to 7, characterized in that, The width of the heat-sealed edge is greater than the thickness of the soft-pack lithium-ion battery.

9. The soft-pack lithium-ion battery according to any one of claims 1 to 7, characterized in that, The battery cell and the battery body formed by the aluminum-plastic film shell are arc-shaped along the length direction.

10. An electronic device, characterized in that, Including the pouch lithium-ion battery as described in any one of claims 1 to 8.

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