A soft package lithium ion battery and a preparation method thereof

Abstract

The application discloses a soft package lithium ion battery and a preparation method thereof. The battery comprises an upper cover and a lower shell movably connected on one side of the upper cover. The lower shell is provided with a containing part for containing a pole core. The lower shell comprises a body and side sealing edges on two sides of the body. A top sealing edge is formed on the top of the body. The top sealing edge is folded and attached to the top of the pole core. The top sealing edge is sequentially provided with a functional structure area for positioning and absorbing the expansion force of the pole lug, a pole lug glue and a pole lug from bottom to top. The application eliminates the root cause of the micro-motion wear of the pole lug by the design of "positioning + buffering", physically, so that the safety of the battery under long-term cycle and vibration working conditions is guaranteed. The application effectively solves the insulation failure risk of the pole lug area caused by dynamic micro-motion in the existing folding packaging technology, and the problem that multiple pole lugs are difficult to be accurately positioned.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, specifically to a soft-pack lithium-ion battery and its preparation method. Background Technology

[0002] Soft-pack lithium-ion batteries are widely used in consumer electronics, electric vehicles, and other fields due to their high energy density and safety advantages. Improving volume utilization is one of the core development directions. Existing technologies, such as patent CN214313347U, propose folding and attaching the top seal edge of an aluminum-plastic film to the cell body to reduce ineffective packaging space. This solution addresses the static insulation problem by applying insulating adhesive or tape to the edge of the top seal edge. However, during research and testing, it was discovered that this structure has inherent defects under dynamic battery conditions: 1) During battery formation, cycling, and use, internal gas generation or external impact can cause slight expansion of the cell, resulting in micron-level relative sliding (micromotion) between the pressed top seal edge and the tabs; 2) Long-term micro-motion friction will gradually wear down / tear the tab adhesive or edge insulation layer, causing it to fail and eventually leading to an internal short circuit in the cell, posing a safety hazard; 3) For designs that use multiple tabs (especially non-transfer soldering, direct-connection multiple tabs) to improve rate performance, after folding, the multiple tabs lack effective positioning and are prone to disordered stacking, further aggravating the risk. At the same time, after bending, slippage is likely to occur, and there are tiny gaps between the tabs, leading to leakage.

[0003] Therefore, there is an urgent need for a new battery structure and packaging method that can fundamentally eliminate micro-motion wear, ensure precise positioning of the tabs, and be compatible with high energy density and high power density designs without changing the mainstream production process. Summary of the Invention

[0004] This invention addresses the problems in existing technologies by disclosing a soft-pack lithium-ion battery and its preparation method. Through a "positioning + buffering" design, this invention can position the tabs and absorb the battery's expansion force. Absorbing the expansion force prevents micron-level relative sliding between the pressed top seal and the tabs during formation, cycling, and use, fundamentally eliminating friction. Positioning the tabs prevents friction caused by long-term micro-movements, eliminating the risk of short circuits within the cell due to tab friction. This effectively solves the problem of insulation failure risk caused by dynamic micro-movements in the tab area in existing folding packaging technologies, as well as the difficulty in accurately positioning multiple tabs.

[0005] This invention is achieved through the following technical solution:

[0006] The present invention first provides a soft-pack lithium-ion battery, including an upper cover and a lower shell movably connected to one side. The lower shell is provided with a receiving part for accommodating the electrode core. The lower shell includes a body and side sealing edges on both sides. A top sealing edge is formed on the top of the body. The top sealing edge is folded and attached to the top of the electrode core. The top sealing edge is provided with a functionalized structural area for positioning the electrode tab and absorbing the battery expansion force, an electrode tab adhesive, and an electrode tab from bottom to top.

[0007] As a further embodiment, the functionalized structural region includes a buffer portion for absorbing battery expansion stress and insulating positioning portions on both sides for constraining the lateral displacement of the tabs.

[0008] As a further option, the edge positioning part is a raised structure, and the side near the electrode tab is a vertical edge.

[0009] As a further option, the insulating positioning part is a rectangular protrusion.

[0010] As a further embodiment, the thickness H of the insulating positioning part is 0.05 mm to 0.20 mm, and the width W of the insulating positioning part is 0.3 mm to 1.0 mm.

[0011] As a further option, the thickness H is selected as 0.1mm.

[0012] As a further option, the width W is selected as 0.6mm.

[0013] As a further improvement, the buffer section is provided with grooves, which are periodically shaped.

[0014] As a further option, the waveform can be wavy or sawtooth-shaped.

[0015] As a further embodiment, the inner distance between the two insulating positioning parts is denoted as D, the width of the bare metal area of ​​the tab is denoted as W_e, and the wavelength of a single waveform of the buffer part is denoted as λ, satisfying the following constraint relationship: 0.5λ≤D-W_e≤2λ.

[0016] As a further option, the wavelength λ ranges from 1.0 mm to 4.0 mm.

[0017] As a further option, the wavelength is 2.5 mm.

[0018] As a further option, when there are multiple electrodes, the distance between two adjacent electrodes is greater than 4λ.

[0019] As a further embodiment, the amplitude A of the buffer section is 0.1mm~0.3mm, and satisfies: A ≥ 0.5H, where H is the thickness of the insulating positioning section.

[0020] As a further option, the amplitude is set at 0.2 mm.

[0021] As a further option, the top sealing edge forms a bend on each side near the side sealing edge.

[0022] As a further option, after the top sealing edge is folded and bonded, the outer surface of the top sealing edge is covered with an insulating layer.

[0023] As a further option, the insulation layer can be insulating tape or coated with UV-cured insulation.

[0024] As a further option, the thickness of the insulation layer is ≥ 0.002 mm.

[0025] As a further option, let L be the width of the top sealing edge before folding, T be the thickness of the cell body, and J be the thickness of the tab. Then, it is necessary to satisfy: L≤T-2J.

[0026] As a further option, the positive electrode of the tab is aluminum, and the negative electrode is nickel or nickel-plated copper.

[0027] As a further option, the thickness of the tab ranges from 0.05mm to 0.15mm.

[0028] As a further option, the lower shell is a three-layer composite structure of nylon / aluminum foil / cast polypropylene or unstretched polypropylene.

[0029] As a further option, the total thickness of the lower shell ranges from 0.08 mm to 0.12 mm, wherein the thickness of the nylon layer ranges from 12 to 25 μm, the thickness of the aluminum foil layer ranges from 35 to 45 μm, and the thickness of the polypropylene layer ranges from 40 to 60 μm.

[0030] As a further option, the thickness of the lower shell is 0.1 mm.

[0031] As a further embodiment, the polypropylene layer is a modified polypropylene resistant to electrolyte corrosion, and its swelling rate after immersion in an electrolyte at 85°C for 720 hours is ≤5%.

[0032] As a further design, the functional structural area, the tab adhesive, and the tab itself are two separate components, with the receiving part being a cavity with an opening at the top.

[0033] This invention also provides a method for manufacturing a soft-pack lithium-ion battery, comprising the following steps:

[0034] S1: Insert the electrode core into the lower casing;

[0035] S2: While using a heat-sealing head for hot-press sealing, a buffer part and its two sides of insulating positioning parts are integrally formed on the polypropylene layer on the inner side of the top sealing edge, so that the electrode tab is located between the two insulating positioning parts; wherein, by controlling the mold parameters, the width D of the two insulating positioning parts, the wavelength λ of the buffer part and the width W_e of the bare metal area of ​​the electrode tab satisfy the following relationship: 0.5λ≤ D-W_e ≤ 2λ;

[0036] S3: Perform the liquid injection and chemical formation process;

[0037] S4: Fold the top sealing edge 90° along the pre-fold line formed by the buffer section and press it onto the top of the cell to complete the encapsulation.

[0038] As a further heat treatment method, the head is hot-pressed at a temperature of 160℃~220℃, a pressure of 0.3MPa~0.8MPa, and a holding time of 2~5 seconds;

[0039] As a further embodiment, the heat sealing head includes a heat sealing body and symmetrically arranged buffer protrusions on its top. Each buffer protrusion has symmetrical positioning grooves on both sides, and the side of the positioning groove closest to the buffer protrusion is a vertical edge.

[0040] The features and beneficial effects of this invention are as follows:

[0041] (1) The present invention eliminates the root cause of the wear of the tab by means of the “positioning + buffering” design, so that the safety of the battery can be guaranteed under long-term cycling and vibration conditions. It can position the tab and absorb the expansion force of the battery. Absorbing the expansion force can prevent the micron-level relative sliding between the top seal edge and the tab during the formation, cycling and use of the battery, fundamentally eliminating friction. Positioning the tab can prevent the tab from friction caused by long-term micro-movement, eliminating the risk of short circuit caused by tab friction inside the cell. It effectively solves the risk of insulation failure caused by dynamic micro-movement in the tab area in the existing flip-packing technology, as well as the problem of difficulty in accurately positioning multiple tabs.

[0042] (2) The buffer section of this invention adopts a periodic corrugated structure, which can provide a larger space for compression and tensile deformation without generating excessive local stress, resulting in better buffering effect. The corrugated shape has a more uniform stress distribution, and the corrugations can disperse concentrated stress to multiple peaks and troughs, avoiding fatigue fracture at a single bend. In addition, the corrugated shape provides a clear bending guide line: in the subsequent folding process, the bottom of the corrugation naturally becomes the bending line, making the folding neater and more consistent.

[0043] (3) By setting the width of the bare metal area of ​​the tab, the inner spacing of the two insulating positioning parts and the wavelength of the buffer part, the present invention enables the tab to be stably positioned and the lateral movement to be strictly limited. The corrugated structure has just the right amount of free deformation space, which can efficiently and uniformly absorb the expansion stress in the Z direction (thickness direction) through the coordinated elastic deformation of multiple waveforms throughout the entire battery life cycle, thereby transforming the "hard friction" between the tab and the aluminum-plastic film into the "elastic deformation" inside the buffer material, fundamentally eliminating fretting wear. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a side view of the battery described in an embodiment of the present invention;

[0046] Figure 2 This is a schematic diagram of the battery structure according to an embodiment of the present invention;

[0047] Figure 3 for Figure 2 Enlarged view of section A in the middle;

[0048] Figure 4 for Figure 3 The main view;

[0049] Figure 5 This is a side view of the lower shell and pole core as described in an embodiment of the present invention;

[0050] Figure 6 This is a schematic diagram illustrating the top sealing edge having a folded angle as described in an embodiment of the present invention;

[0051] Figure 7 This is a schematic diagram of one embodiment of the buffer section described in this invention;

[0052] Figure 8 This is a schematic diagram of another embodiment of the buffer section described in this invention;

[0053] Figure 9 This is a schematic diagram of the structure of the heat sealing head according to an embodiment of the present invention.

[0054] Explanation of reference numerals in the attached figures:

[0055] 1-Lower shell; 11-Accommodation part; 12-Side sealing edge; 13-Top sealing edge; 14-Functionalized structural area; 141-Buffer part; 142-Insulation positioning part; 15-Electrode tab adhesive; 16-Electrode tab; 2-Upper cover; 3-Electrode core; 4-Separator; 5-Heat sealing head; 51-Positioning groove; 52-Buffer protrusion. Detailed Implementation

[0056] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0057] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, 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 a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0058] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] like Figures 1 to 9 As shown, a soft-pack lithium-ion battery includes an upper cover 2 and a lower shell 1 movably connected to one side. The lower shell 1 has a receiving portion 11 for accommodating an electrode core 3. The lower shell 1 includes a body and side sealing edges 12 on both sides. A top sealing edge 13 is formed on the top of the body. The top sealing edge 13 is folded and attached to the top of the electrode core 3. The top sealing edge 13 has a functionalized structural area 14 for positioning the electrode tabs and absorbing the battery expansion force, an electrode tab adhesive 15, and an electrode tab 16 from bottom to top.

[0060] The battery of this application, through the functionalized structural region 14, can position the tabs and absorb the expansion force of the battery. Absorbing the expansion force can prevent micron-level relative sliding between the pressed top seal edge and the tabs during formation, cycling, and use, fundamentally eliminating friction. Positioning the tabs can prevent friction caused by long-term micro-movements of the tabs, eliminating the risk of short circuits caused by tab friction inside the cell. It effectively solves the problem of insulation failure risk caused by dynamic micro-movements in the tab area in existing folding packaging technology, as well as the problem of difficulty in accurately positioning multiple tabs.

[0061] In some embodiments, after the top sealing edge 13 is folded and bonded, the outer surface of the top sealing edge 13 is covered with an insulating layer.

[0062] Preferably, the insulating layer is insulating tape or coated with UV-cured insulating varnish;

[0063] Preferably, the thickness of the insulating layer is ≥ 0.002 mm.

[0064] The insulation layer serves as redundant protection for the top seal edge, effectively preventing the risk of short circuit caused by external force contacting the electrode tab.

[0065] In some embodiments, the receiving portion 11 is a cavity with an opening at the top.

[0066] In some embodiments, there are two functionalized structural regions 14, two tab adhesives 15, and two tabs 16, which are arranged symmetrically.

[0067] In some embodiments, the lower shell 1 adopts a three-layer composite structure of nylon (ONy) / aluminum foil (AL) / cast polypropylene (CPP) or unstretched polypropylene (CPP).

[0068] The total thickness of the lower shell 1 ranges from 0.08 mm to 0.12 mm, of which the thickness of the ONy layer ranges from 12 to 25 μm, the thickness of the AL layer ranges from 35 to 45 μm, and the thickness of the CPP layer ranges from 40 to 60 μm. The CPP layer must have good heat-sealing and ductility.

[0069] Preferably, the thickness of the lower shell 1 is 0.1 mm;

[0070] The material of tab 16 can be aluminum (positive electrode), nickel, or nickel-plated copper (negative electrode), and the thickness of tab 16 ranges from 0.05mm to 0.15mm.

[0071] In some embodiments, the electrode core 3 is manufactured using a winding or stacking process, and is compatible with cathode systems such as high-nickel ternary and lithium iron phosphate.

[0072] In some embodiments, the width of the top sealing edge 13 before folding is denoted as L, the thickness of the cell body is denoted as T, and the thickness of the tab 16 is denoted as J. Then, it is necessary to satisfy: L≤T-2J. Satisfying this relationship can ensure that the outer edge of the top sealing edge 13 does not exceed the side of the cell after folding, making the battery structure more compact and saving space. At the same time, it avoids material waste caused by excessive size, or difficulty in fully installing into the lower shell 1, causing assembly difficulties.

[0073] In some embodiments, the functionalized structural region 14 includes a buffer portion 141 for absorbing battery expansion stress and insulating positioning portions 142 on both sides thereof, the insulating positioning portions 142 being used to constrain the lateral displacement of the tabs.

[0074] This application, through a "positioning + buffering" design, physically eliminates the root cause of fretting wear on the tabs, ensuring battery safety under long-term cycling and vibration conditions. When the battery expands, the pressure forces the buffer zone to undergo elastic deformation. The buffer zone absorbs the deformation and expansion stress of the tabs in the cell thickness direction, thus alleviating hard friction between the tabs and between the tabs and the aluminum-plastic film, preventing the tabs from being subjected to hard compression and friction in the vertical direction.

[0075] In some embodiments, the functionalized structural region 14 is located in the inner layer (polypropylene layer) of the aluminum-plastic film of the top sealing edge 13 and is formed by hot pressing by the heat sealing head 5.

[0076] The heat sealing head 5 includes a heat sealing body and symmetrically arranged buffer protrusions 52 on its top. Each buffer protrusion 52 has symmetrical positioning grooves 51 on both sides, and the side of the positioning groove 51 closest to the buffer protrusion 52 is a vertical side, which facilitates the positioning of the tab 16.

[0077] The heat-sealing head has a simple structure and is easy to operate, which simplifies the battery manufacturing process.

[0078] The buffer protrusion 52 is used for thermoforming the buffer part 141, and the positioning groove 51 is used for thermoforming the insulating positioning part 142.

[0079] In some embodiments, the insulating positioning part 142 is a raised structure, and the side near the electrode tab is a vertical edge, so that the electrode tab is firmly restricted within a safe area and will not slide left or right, affecting the top seal or causing a short circuit.

[0080] Preferably, the insulating positioning part 142 is a rectangular protrusion with a width denoted as W, a thickness denoted as H, and a height that is the same as the height of the top sealing edge;

[0081] Therefore, the thickness H of the insulating positioning part 142 is in the range of 0.05 mm to 0.20 mm, and preferably, the thickness is 0.1 mm;

[0082] The width W of the insulating positioning part 142 is 0.3 mm to 1.0 mm, preferably 0.6 mm.

[0083] In some embodiments, the buffer portion 141 is shaped as a uniformly distributed continuous or discontinuous groove.

[0084] In other embodiments, the buffer portion 141 is shaped as a corrugated or sawtooth shape with a periodic waveform.

[0085] Preferably, the shape of the buffer section 141 is corrugated; the larger deformation stroke of the corrugated shape can provide a larger space for compression and tensile deformation without generating excessive local stress, resulting in better buffering effect. The corrugated shape has a more uniform stress distribution, and the corrugations can disperse concentrated stress to multiple peaks and troughs, avoiding fatigue fracture at a single bend. In addition, the corrugated shape provides a clear bending guide line: in the subsequent folding process, the bottom of the corrugation naturally becomes the bending line, making the folding neater and more consistent.

[0086] In some embodiments, the inner distance between the two insulating positioning portions 142 is denoted as D, the width of the bare metal area of ​​the tab is denoted as W_e (the tab does not include the portion of the insulating adhesive), and the wavelength of a single waveform of the buffer portion 141 is λ, satisfying the following constraint relationship: 0.5λ≤(D-W_e) ≤2λ.

[0087] In some embodiments, the wavelength λ ranges from 1.0 mm to 4.0 mm. If the wavelength is too small, the mold processing becomes difficult, the CPP material flow and filling are poor, and stress concentration is likely to occur at the root of the corrugations. If the wavelength is too large, the buffer deformation stroke per unit length is small, resulting in low buffering efficiency. Preferably, the wavelength is 2.5 mm.

[0088] The amplitude A of the buffer portion 141 is 0.1 mm to 0.3 mm, and satisfies: A ≥ 0.5H, where H is the thickness of the insulating positioning portion 142.

[0089] Too small an amplitude results in limited deformation space and ineffective buffering; too large an amplitude leads to excessive thinning of the CPP layer, weakening the overall longitudinal tensile strength of the top sealing edge. Preferably, the amplitude is 0.2 mm.

[0090] The preferred corrugated cross-sectional shape is a sinusoidal or circular arc waveform, as this shape provides the most uniform stress distribution and a long fatigue life. The material wall thickness at the bottom of the corrugations should be no less than 50% of the original thickness of the inner layer of the aluminum-plastic film to ensure structural integrity.

[0091] In some embodiments, the top sealing edge 13 forms a bend 17 on each side near the side sealing edge 12.

[0092] The present invention also includes a method for preparing a soft-pack lithium-ion battery, comprising the following steps:

[0093] S1: Insert the pole core 3 into the lower shell 1;

[0094] S2: Perform the top sealing process. While using the heat sealing head 5 to heat-press and seal, a buffer part 141 and its two sides of insulating positioning parts 142 are integrally formed on the CPP layer inside the top sealing edge 13, so that the electrode tab 16 is located between the two insulating positioning parts 142. Among them, by controlling the mold parameters, the width D of the two insulating positioning parts 142, the wavelength λ of the buffer part and the width W_e of the bare metal area of ​​the electrode tab satisfy the following relationship: 0.5λ ≤ (D - W_e) ≤ 2λ.

[0095] In one embodiment, the hot-pressing temperature of the heat-sealing head is 160℃~220℃, the pressure is 0.3MPa~0.8MPa, and the holding time is 2~5 seconds.

[0096] S3: Perform subsequent processes such as liquid injection and chemical formation;

[0097] S4: Finally, along the pre-fold line formed by the buffer section 141, the top sealing edge 13 is folded 90° and pressed and attached to the top of the cell to complete the encapsulation.

[0098] Preferably, after the top edge is folded and bonded in S4, an additional insulating layer can be applied to the outer surface of the top edge as redundant protection.

[0099] Preferably, the insulating layer is insulating tape or coated with UV-cured insulating varnish;

[0100] The thickness of the insulation layer is ≥ 0.002 mm.

[0101] In this method, all structures are completed simultaneously within the existing standard top-sealing process, without adding any extra production steps or materials. Only the heat-sealing head mold needs modification, resulting in extremely low modification costs and easy scalability. This method solves the multi-tab control problem and provides a reliable packaging solution for developing batteries with higher energy density and higher power.

[0102] Example 1

[0103] The lower shell 1 adopts a three-layer composite structure of nylon (ONy), aluminum foil (AL), and cast polypropylene (CPP), with a total thickness of 0.116 mm. The electrode tabs are made of aluminum with a thickness of 0.1 mm, and the width of the bare metal area of ​​the electrode tabs is W_e = 8.0 mm. The electrode core is a high-nickel ternary cell manufactured by a lamination process. The width of the top sealing edge is less than the thickness of the cell. The functionalized structural area 14 is integrally hot-pressed and formed using a heat sealing head under the conditions of 180℃ temperature, 0.5 MPa pressure, and 3 seconds holding time.

[0104] The inner spacing between the two insulating positioning parts is D = 8.5 mm, and the wavelength of the buffer part is λ = 1.0 mm. Therefore, D - W_e = 0.5 mm, satisfying 0.5λ ≤ (D - W_e) ≤ 2λ (i.e., 0.5 mm ≤ 0.5 mm ≤ 2.0 mm). The amplitude of the buffer part is A = 0.15 mm, and the thickness of the insulating positioning part 142 is H = 0.1 mm, satisfying A ≥ 0.5H.

[0105] Example 2

[0106] The difference between Example 2 and Example 1 is that the inner distance between the two insulating positioning parts is D = 10.0 mm, and the wavelength of the buffer part is λ = 2.0 mm. Therefore, D - W_e = 2.0 mm, satisfying 0.5λ ≤ (D - W_e) ≤ 2λ (i.e., 1.0 mm ≤ 2.0 mm ≤ 4.0 mm). The amplitude of the buffer part is A = 0.2 mm, and the thickness of the insulating positioning part 142 is H = 0.15 mm, satisfying A ≥ 0.5H. All other conditions are the same as in Example 1.

[0107] Comparative Example 1

[0108] The difference between Comparative Example 1 and Example 1 is that the inner spacing D between the two insulating positioning parts is 8.2 mm (only 0.2 mm wider than the tab), and the wavelength λ of the buffer part is 2.0 mm. Therefore, (D - W_e) = 0.2 mm, which is less than 0.5λ (1.0 mm). All other conditions are the same as in Example 1. The product obtained through Comparative Example 1 has difficulty assembling the tab, and the deformation space of the buffer part is excessively compressed by the tab, resulting in high initial stress.

[0109] Comparative Example 2

[0110] The difference between Comparative Example 2 and Example 1 is that the inner distance between the two insulating positioning parts, D = 15.0 mm, and the wavelength of the buffer part, λ = 1.0 mm. Therefore, (D - W_e) = 7.0 mm, which is much larger than 2λ (2.0 mm). All other conditions are the same as in Example 1. The product obtained through Comparative Example 2 has excessive lateral movement space between the tabs and ribs, resulting in positioning failure and significant lateral micro-movements under vibration.

[0111] Comparative Example 3

[0112] A flat groove is used as the buffer section (i.e., a non-periodic waveform structure), and other dimensions are the same as in Example 1.

[0113] The batteries prepared in Examples 1-2 and Comparative Examples 1-3 were tested as follows:

[0114] A1. After 500 charge-discharge cycles, disassemble and check the wear of the tab adhesive.

[0115] A2. After simulated vibration test (frequency 50Hz, acceleration 10g, time 24h), measure the insulation resistance;

[0116] A3. Evaluate the neatness and ease of assembly of the multi-pole tabs (4 parallel tabs).

[0117] The test results are as follows:

[0118] Examples 1 and 2: After cycling, the tab adhesive showed no visible wear, and the insulation resistance retention rate after vibration was >99%. The multi-tab assembly was neat and orderly, without any interlacing or disorder. The corrugations in the buffer section deformed uniformly during folding and expansion, effectively absorbing stress.

[0119] Comparative Example 1: The assembly yield was low, and after cycling, some batteries showed slight wear on the insulating adhesive at the edge of the tabs, indicating poor buffering effect.

[0120] Comparative Example 2: After vibration testing, the insulation resistance decreased by about 5%. Upon disassembly, it was found that the electrode tabs had lateral sliding marks, and the positioning function was basically ineffective.

[0121] Comparative Example 3: After cycling, localized stress marks appeared on the aluminum-plastic film CPP layer corresponding to the buffer area, the fold lines were not uniform, and some batteries had micro-cracks at the bending points, posing a risk to long-term reliability.

[0122] Through the experimental results of the above embodiments and comparative examples, it can be found that by introducing the constraint 0.5λ≤(D - W_e) ≤ 2λ, unexpected technical effects were achieved.

[0123] When D - W_e < 0.5λ, the tab gap is too small, which not only makes assembly difficult, but more importantly, it severely restricts the initial deformation space of the corrugated structure. This causes the buffer part to reach its deformation limit during the initial expansion stage of the battery, lose its buffering capacity, and revert to a state similar to hard contact, thus exacerbating the risk of fretting wear.

[0124] When D - W_e > 2λ, the gap between the electrodes is too large, exceeding the range that the corrugated structure can effectively transmit and disperse stress within one cycle, resulting in inaccurate electrode positioning and the inability to suppress lateral micro-movements.

[0125] When 0.5λ≤(D - W_e) ≤ 2λ, the characteristic wavelength of the tab gap and the buffer section achieves optimal matching. This matching relationship ensures that: ① the tab can be stably positioned, and lateral movement is strictly limited; ② the corrugated structure has just the right amount of free deformation space, which can efficiently and uniformly absorb the expansion stress in the Z-direction (thickness direction) through the coordinated elastic deformation of multiple waveforms throughout the entire battery life, thereby transforming the "hard friction" between the tab and the aluminum-plastic film into "elastic deformation" within the buffer material, fundamentally eliminating fretting wear. This "positioning-buffering" synergistic effect achieved through geometric parameter constraints is not readily apparent to those skilled in the art.

[0126] This embodiment also provides a computer device applicable to a method for manufacturing a pouch lithium-ion battery, including a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for manufacturing a pouch lithium-ion battery as proposed in the above embodiment.

[0127] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements a method for manufacturing a soft-pack lithium-ion battery as described in the above embodiments.

[0128] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0129] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0130] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0131] More specific examples (a non-exhaustive list) of computer-readable media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other media, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0132] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0133] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A soft-pack lithium-ion battery, comprising an upper cover and a lower shell movably connected to one side thereof, the lower shell having a receiving portion for accommodating an electrode core, characterized in that: The lower shell includes the main body and the side seals on both sides. The top of the main body forms a top seal, which is folded and attached to the top of the electrode core. From bottom to top, the top seal has a functional structure area for positioning the electrode tabs and absorbing the battery expansion force, electrode tab adhesive, and electrode tabs.

2. A soft-pack lithium-ion battery according to claim 1, characterized in that: The functionalized structural region includes a buffer section for absorbing battery expansion stress and insulating positioning sections on both sides for constraining the lateral displacement of the electrode tabs. Preferably, the edge positioning part has a raised structure, and the side near the electrode tab is a vertical edge; Preferably, the insulating positioning part is a rectangular protrusion; Preferably, the thickness H of the insulating positioning part is 0.05 mm to 0.20 mm, and the width W of the insulating positioning part is 0.3 mm to 1.0 mm; Preferably, the thickness H is 0.1 mm; Preferably, the width W is 0.6mm; Preferably, the buffer section has a groove, and the groove has a periodic waveform; Preferably, the waveform is wavy or sawtooth-shaped.

3. A soft-pack lithium-ion battery according to claim 2, characterized in that: The inner distance between the two insulating positioning parts is denoted as D, the width of the bare metal area of ​​the electrode tab is denoted as W_e, and the wavelength of a single waveform of the buffer part is denoted as λ, satisfying the following constraint relationship: 0.5λ≤D-W_e≤2λ; Preferably, the wavelength λ is in the range of 1.0 mm to 4.0 mm; Preferably, the wavelength is 2.5 mm; Preferably, when there are multiple electrodes, the distance between two adjacent electrodes is greater than 4λ.

4. A soft-pack lithium-ion battery according to claim 3, characterized in that: The amplitude A of the buffer section is 0.1mm~0.3mm, and satisfies: A ≥ 0.5H, where H is the thickness of the insulating positioning section; Preferably, the amplitude is 0.2 mm.

5. A soft-pack lithium-ion battery according to claim 1, characterized in that: The top sealing edge forms a bend on each of the two sides near the side sealing edge.

6. A soft-pack lithium-ion battery according to claim 1, characterized in that: After the top sealing edge is folded and bonded, the outer surface of the top sealing edge is covered with an insulating layer; Preferably, the insulating layer is insulating tape or coated with UV-cured insulating varnish; Preferably, the thickness of the insulating layer is ≥ 0.002 mm; Preferably, the width of the top sealing edge before folding is denoted as L, the thickness of the cell body is denoted as T, and the thickness of the tab is denoted as J. Then, it is necessary to satisfy: L≤T-2J; Preferably, the positive electrode of the tab is aluminum, and the negative electrode is nickel or nickel-plated copper; Preferably, the thickness of the electrode tab is in the range of 0.05mm to 0.15mm.

7. A soft-pack lithium-ion battery according to claim 1, characterized in that: The lower shell is a three-layer composite structure of nylon / aluminum foil / cast polypropylene or unstretched polypropylene; Preferably, the total thickness of the lower shell ranges from 0.08 mm to 0.12 mm, wherein the thickness of the nylon layer ranges from 12 to 25 μm, the thickness of the aluminum foil layer ranges from 35 to 45 μm, and the thickness of the polypropylene layer ranges from 40 to 60 μm. Preferably, the thickness of the lower shell is 0.1 mm; Preferably, the polypropylene layer is modified polypropylene resistant to electrolyte corrosion, and its swelling rate after immersion in an electrolyte at 85°C for 720 hours is ≤5%.

8. A soft-pack lithium-ion battery according to claim 1, characterized in that: The functional structure area, the tab adhesive, and the tab itself are two separate parts, and the receiving part is a cavity with an opening at the top.

9. A method for manufacturing a soft-pack lithium-ion battery according to any one of claims 1 to 8, characterized in that: Includes the following steps: S1: Insert the electrode core into the lower casing; S2: While using a heat-sealing head for hot-press sealing, a buffer part and its two sides of insulating positioning parts are integrally formed on the polypropylene layer on the inner side of the top sealing edge, so that the electrode tab is located between the two insulating positioning parts; wherein, by controlling the mold parameters, the width D of the two insulating positioning parts, the wavelength λ of the buffer part and the width W_e of the bare metal area of ​​the electrode tab satisfy the following relationship: 0.5λ ≤ D-W_e ≤ 2λ; S3: Perform the liquid injection and chemical formation process; S4: Fold the top sealing edge 90° along the pre-fold line formed by the buffer section and press it onto the top of the cell to complete the encapsulation.

10. A method for manufacturing a soft-pack lithium-ion battery according to claim 9, characterized in that: The hot-pressing temperature of the heat-sealing head is 160℃~220℃, the pressure is 0.3MPa~0.8MPa, and the holding time is 2~5 seconds; Preferably, the heat sealing head includes a heat sealing body and symmetrically arranged buffer protrusions on its top. Each buffer protrusion has symmetrical positioning grooves on both sides, and the side of the positioning groove closest to the buffer protrusion is a vertical edge.

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