Pouch cell

Abstract

This invention relates to the field of secondary battery technology and discloses a pouch battery, including a membrane housing and an electrode assembly. The membrane housing includes a first sealing edge, and the electrode assembly is disposed within the membrane housing. The electrode assembly includes a cell and a first adapter tab. The cell includes a cell body and multiple layers of first tab sheets extending from the cell body toward the first sealing edge. The multiple layers of first tab sheets are stacked along a third direction to form a first tab cluster and are welded to the first adapter tab to form a first solder area. Along a first direction parallel to the extension direction of the first tab sheets, the end of the first adapter tab away from the first tab sheet extends out of the membrane housing via the first sealing edge. Along a second direction, the size of the first tab sheet is D, and the size of the pouch battery is L, satisfying 0.5 ≤ D / L ≤ 1. At least one layer of the first tab sheet has a first through hole. This invention can improve the overcurrent capacity and the smoothness of gas generation and exhaust during high-rate charge and discharge scenarios.

Description

Technical Field

[0001] This invention relates to the field of secondary battery technology, specifically to pouch batteries. Background Technology

[0002] Due to their high energy density and high rate capability, pouch batteries are widely used in various electrical devices. For example, pouch batteries can be used in electric aircraft, power tools, and consumer electronics.

[0003] Typically, the tabs of a pouch cell extend from the edge of the casing seal. However, under high-rate discharge conditions, the tabs have limited overcurrent capacity, leading to concentrated current density in the tab area and a significant temperature rise on the tab side, thus reducing the battery's charge and discharge performance. Furthermore, insufficient electrolyte wetting inside the cell and difficulty in effectively venting gases generated during formation further affect electrode consistency and charge / discharge performance. Summary of the Invention

[0004] This invention provides a pouch battery to solve the problems of insufficient overcurrent capacity, excessively high electrode temperature rise, insufficient electrolyte wetting, and formation gas retention in pouch batteries under high-rate charge and discharge scenarios.

[0005] The pouch battery of the present invention includes a membrane housing and an electrode assembly. The membrane housing includes a first sealing edge. The electrode assembly is disposed within the membrane housing and includes a cell and a first adapter tab. The cell includes a cell body and multiple layers of first tab sheets extending from the cell body toward the first sealing edge. The multiple layers of first tab sheets are stacked along a third direction to form a first tab cluster and are welded to the first adapter tab to form a first solder area. Along a first direction parallel to the extension direction of the first tab, the end of the first adapter tab away from the first tab sheet extends out of the membrane housing via the first sealing edge. Along a second direction, the size of the first tab sheet is D, and the size of the pouch battery is L, satisfying 0.5 ≤ D / L ≤ 1. At least one layer of the first tab sheet has a first through hole, and the first direction, the second direction, and the third direction are mutually perpendicular.

[0006] This multi-layered stacked first tab configuration effectively enhances current carrying capacity, reduces heat generation during high-rate charge and discharge, and improves battery charge and discharge performance, allowing the battery to maintain a lower operating temperature in high-rate applications. By controlling the appropriate ratio of the width D of the first tab to the width L of the pouch cell, the tab width is significantly increased, resulting in a larger current carrying area. This reduces the current density in the tab area during high-rate discharge, decreases heat generation from the tab, lowers battery temperature rise, improves cycle performance and lifespan, and reduces the risk of the first tab puncturing the membrane. Simultaneously, a first through-hole is provided on at least one layer of the first tab, offering additional wetting channels for the electrolyte, alleviating the problem of difficult wetting within the cell, and improving the consistency of electrode wetting. Furthermore, the first through-hole provides a venting path for gases generated during the formation stage, reducing gas retention within the cell, mitigating the adverse effects of gas resistance on the electrolyte wetting channels, and further enhancing the battery's charge and discharge performance. Attached Figure Description

[0007] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the structure of a soft-pack battery according to an embodiment of the present invention; Figure 2 This is a partial structural diagram of a soft-pack battery after the membrane shell has been removed, according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the insulating protective layer according to an embodiment of the present invention.

[0009] Explanation of reference numerals in the attached figures: 10 - Membrane shell; 11 - First sealing edge; 12 - Second sealing edge; 20-Battery cell; 21-Battery cell body; 22-First electrode tab; 22a-Beveled cut; 221-First through hole; 23-First adapter tab; 24-First soldering area; 25-Second adapter tab; 26-Taper adhesive; 30 - Insulating protective layer; 31 - Second through hole; 30a - First bonding area; 30b - Second bonding area; X - First direction; Y - Second direction; Z - Third direction. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] Currently, higher requirements are being placed on the energy density and charge / discharge performance of pouch batteries. Under high-rate charge / discharge scenarios, pouch batteries experience concentrated current density in the tab area, leading to significant temperature rise in the tabs, shortened battery cycle life, and increased risk of safety runaway. Simultaneously, the longer electrolyte wetting path within the cell makes it difficult to fully wet the central area, and the accumulation of gases generated during formation hinders electrolyte wetting channels, affecting electrode consistency and battery charge / discharge performance.

[0012] To address the issues of insufficient overcurrent capacity, excessively high tab temperature rise, insufficient electrolyte wetting, and formation gas retention in high-rate charge / discharge scenarios of pouch batteries, this application provides a pouch battery. The pouch battery includes a casing and an electrode assembly. The casing includes a first sealing edge. The electrode assembly is disposed within the casing and includes a cell and a first adapter tab. The cell includes a cell body and multiple layers of first tab sheets extending from the cell body towards the first sealing edge. The multiple layers of first tab sheets are stacked along a third direction and welded to the first adapter tab to form a first solder area. Along the first direction, the end of the first adapter tab away from the first tab sheet extends out of the casing via the first sealing edge. Along the second direction, the dimensions of the multiple layers of first tab sheets are D, and the dimensions of the pouch battery are L, satisfying 0.5 ≤ D / L < 1, and at least one layer of the first tab sheets has a first through-hole.

[0013] This multi-layered stacked first tab configuration effectively enhances current carrying capacity, reduces heat generation during high-rate charge and discharge, and improves battery charge and discharge performance, allowing the battery to maintain a lower operating temperature in high-rate applications. By controlling the ratio of the width D of the first tab to the width L of the pouch cell to satisfy 0.5 ≤ D / L < 1, the tab width is significantly increased, the current carrying area is correspondingly increased, the current density in the tab area is reduced during high-rate discharge, the heat generated by the tab is reduced, the battery temperature rise is reduced, the cycle life is extended, and the risk of thermal runaway is reduced. Simultaneously, a first through-hole is provided on at least one layer of the first tab, providing an additional wetting channel for the electrolyte, improving the problem of difficult wetting inside the cell, and enhancing the consistency of electrode wetting. Furthermore, the first through-hole provides an exhaust path for gases generated during the formation stage, reducing gas retention inside the cell, mitigating the adverse effects of gas resistance on the electrolyte wetting channel, and further improving the battery's charge and discharge performance.

[0014] The following is combined Figures 1 to 3 The embodiments of the present invention will be described in detail below.

[0015] This application provides a pouch battery. The pouch battery includes a housing 10 and an electrode assembly. The housing 10 includes a first sealing edge 11. The electrode assembly is disposed within the housing 10 and includes a cell 20 and a first adapter tab 23. The cell 20 includes a cell body 21 and multiple layers of first tab sheets 22 extending from the cell body 21 toward the first sealing edge 11. The multiple layers of first tab sheets 22 are stacked along a third direction Z and welded to the first adapter tab 23 to form a first solder area 24. Along a first direction X parallel to the extension direction of the first tab sheet 22, the end of the first adapter tab 23 away from the first tab sheet 22 extends out of the housing 10 via the first sealing edge 11. Along a second direction Y, the size of the first tab sheet 22 is D, and the size of the pouch battery is L, satisfying 0.5 ≤ D / L < 1. At least one layer of the first tab sheet 22 has a first through hole 221. The first direction X, the second direction Y, and the third direction Z are all perpendicular to each other.

[0016] The membrane shell 10 is the external encapsulation structure of the soft-pack battery and can be made of aluminum-plastic composite film. The membrane shell 10 is sealed by heat sealing process.

[0017] The first sealing edge 11 is a sealing structure formed by hot pressing one side edge of the membrane housing 10 along the first direction X, used to seal the electrode assembly inside the membrane housing 10, and at the same time provide an extension channel for the first adapter tab 23.

[0018] The electrode assembly includes a cell 20 and a first adapter tab 23. The cell 20 is the main structure inside the battery that realizes electrochemical reactions and energy storage. The cell 20 includes a cell body 21 and a multilayer first tab sheet 22 extending from the cell body 21 toward the first sealing edge 11.

[0019] The cell body 21 can be formed by winding a positive electrode, a negative electrode, and a separator spaced between the positive and negative electrode. The current collector surfaces of the positive and negative electrode have active material layers, and the separator is used to prevent direct contact between the positive and negative electrode while allowing lithium ions to pass through.

[0020] The multilayer first electrode tab 22 is a multilayer first electrode tab foil extending from the same side of the cell body 21. Each layer of the first electrode tab 22 is formed by extending the portion of the current collector of the corresponding electrode that is not coated with active material, that is, the first electrode tab 22 is integrally formed with the corresponding electrode. The first electrode tab 22 can be a positive electrode tab or a negative electrode tab.

[0021] The multi-layered first electrode tabs 22 are stacked along the third direction Z, which is perpendicular to the large surface of the cell body 21. The stacked multi-layered first electrode tabs 22 form a first electrode tab cluster with a certain thickness.

[0022] The first adapter tab 23 can be a metal conductive component with a certain thickness and rigidity, and the material can be any one of copper, aluminum, nickel, or copper alloy or aluminum alloy.

[0023] One end of the first adapter tab 23 is welded to the stacked multilayer first tab sheet 22 to form a first solder area 24, and the other end extends from the inside of the membrane housing 10 to the outside along the first direction X and protrudes from the outside of the membrane housing 10 via the first sealing edge 11 for connection with external circuitry. It can be understood that the first adapter tab 23 can be straight along the first direction X or it can have a certain degree of curvature. The first adapter tab 23 may be provided with tab adhesive 26, which is bonded to the first sealing edge by heat pressing.

[0024] The first soldering area 24 can be a bonding area formed by ultrasonic welding, resistance welding or laser welding of the multilayer first electrode tab 22 and the first adapter tab 23.

[0025] Along the second direction Y, the size of the first electrode tab 22 is D, which is the width of the first electrode tab 22 in the direction perpendicular to the first direction X and parallel to the large surface of the cell body 21.

[0026] The size of the pouch battery is L, which is the overall width of the finished pouch battery in the second direction Y.

[0027] In some embodiments, the first tab 22 may be a trapezoidal structure, where dimension D refers to the maximum dimension.

[0028] The first direction X, the second direction Y, and the third direction Z are all perpendicular to each other, forming a mutually orthogonal three-dimensional coordinate system.

[0029] At least one layer of the first electrode tab 22 is provided with a first through hole 221, which is a hole structure that penetrates the thickness direction of the first electrode tab 22. The first through hole 221 extends through the first electrode tab 22 along the thickness direction, forming a channel for electrolyte and gas. The first through hole 221 can be provided on one, two or more layers of multilayer first electrode tabs 22.

[0030] The size D of the first electrode tab 22 can be measured by non-destructively disassembling the battery to expose the first electrode tab 22, and then measuring the maximum width of the first electrode tab 22 along the second direction Y using a vernier caliper or a reading microscope.

[0031] The size L of the pouch battery can be measured by using vernier calipers to measure the maximum width of the finished pouch battery's outer contour along the second direction Y.

[0032] If the D / L ratio is too large, the width of the first tab 22 will be close to or exceed the overall width of the battery. The edge of the tab will be too close to the side edge of the housing 10, resulting in insufficient spacing between the tab and the side seal of the housing 10 during encapsulation. This can easily cause the first tab 22 to puncture the housing 10, leading to a short circuit. If the D / L ratio is too small, the width of the first tab 22 will be too narrow, resulting in insufficient effective current-carrying area. During high-rate charging and discharging, the current density in the tab area will be significantly concentrated, increasing heat generation and temperature rise. This limits the current carrying capacity, reduces the battery's high-rate charging and discharging performance, and shortens its cycle life. Therefore, by controlling the D / L ratio to be 0.5 ≤ D / L < 1, it is possible to ensure that the first tab 22 has sufficient current-carrying area to reduce current density and heat generation during high-rate discharge, while also providing sufficient safety clearance for the housing 10 encapsulation, thus ensuring battery safety.

[0033] For example, the D / L ratio can be 0.50, 0.53, 0.56, 0.59, 0.62, 0.68, 0.73, 0.77, 0.82, 0.86, 0.91, 0.94, 0.97, 0.99, or a value within the range of any two of the above values.

[0034] The multi-layer first tab 22 is stacked along the third direction Z and then welded to the first adapter tab 23. The multi-layer first tab 22 stacked structure effectively improves the current carrying capacity, reduces the current density in the tab area during high-rate charging and discharging, reduces heat generation in the tab, and enables the battery to maintain a lower operating temperature in high-rate application scenarios, thus improving charge and discharge performance. By controlling the ratio of the width D of the first tab 22 to the width L of the pouch battery within the range of 0.5 to 1, the current carrying area of ​​the tab is significantly increased, the current density in the tab area is further reduced during high-rate discharge, heat generation in the tab is reduced, battery temperature rise is reduced, cycle stability is improved, and the risk of thermal runaway is reduced. Simultaneously, a first through-hole 221 is provided on at least one layer of the first electrode tab 22. The first through-hole 221 provides an additional wetting channel for the electrolyte, allowing the electrolyte to wet into the center of the first electrode tab cluster through the first through-hole and the interlayer gaps between the multiple layers of the first electrode tabs connected to the first through-hole. Then, it enters the interior of the cell through the gaps between the cell electrodes, improving the consistency of wetting inside the cell 20 and enhancing the uniformity of electrode wetting. In addition, the first through-hole 221 provides a path for the gas generated inside the cell 20 during the formation stage to be discharged to the outside, reducing the amount of gas retained inside the cell 20, reducing the blocking effect of gas accumulation on the electrolyte wetting channel, reducing gas resistance, further improving electrolyte wetting efficiency, further improving electrode uniformity, and further improving the charge and discharge performance of the battery.

[0035] In some embodiments, the first through hole 221 is located outside the first solder area 24. Along the third direction Z, the first through hole 221 is provided on at least one side of the center of the first electrode cluster formed by the multilayer first electrode tab 22.

[0036] The first through hole 221 is located outside the first soldering area 24, that is, the projection area of ​​the first through hole 221 along the third direction Z on the plane of the first electrode tab 22 does not overlap with the projection area of ​​the first soldering area 24 along the third direction Z on the plane of the first electrode tab 22, that is, the first through hole 221 is set to avoid the first soldering area 24.

[0037] The center of the multilayer first electrode tab 22 refers to the middle position of the first electrode tab cluster formed by the stacking of the multilayer first electrode tabs 22 along the third direction Z. A first through hole 221 is provided on at least one side of the center of the multilayer first electrode tab 22, that is, on one or both sides of the center of the multilayer first electrode tab 22.

[0038] The first through-hole 221 is positioned away from the first solder area 24 to avoid weakening the structural strength of the first electrode tab 22 at the first solder area 24 and reduce the risk of breakage at the welding position. Since it is necessary to ensure that each electrode of the cell is immersed in electrolyte, and since gas generated in the cell will accumulate in the middle, the first through-hole 221 is provided on at least one side of the first electrode tab 22 at the center of the multi-layer first electrode tab 22. That is, at least half of the first electrode tabs 22 are provided with the first through-hole 221, providing an effective channel for electrolyte wetting and formation gas venting. This improves electrolyte penetration efficiency and coverage uniformity, facilitates smooth gas venting, reduces gas retention, further improves the internal wetting consistency of the cell 20, and further enhances the battery's charge and discharge performance.

[0039] In some embodiments, along the third direction Z, the ratio S1 / S of the total projected area S1 of the first through hole 221 to the projected area S of the first tab 22 is in the range of 5% ≤ S1 / S ≤ 45%.

[0040] Along the third direction Z, the first pole piece 22 forms a planar projection with a certain area and shape on the projection plane perpendicular to the third direction Z, but the projection area of ​​the first pole piece 22 on the plane formed by the second direction Y and the first direction X is denoted as S.

[0041] The total projected area S1 of the first through hole 221 is the sum of the projected areas of the first through holes 221 on all the first pole tabs 22 on the same projection plane along the third direction Z. When the first through holes 221 on multiple layers of first pole tabs 22 overlap along the third direction Z, the projected area of ​​the overlapping part is not counted repeatedly in S1.

[0042] If the S1 / S ratio is too large, the proportion of the total area of ​​the first through-hole 221 on the first electrode tab 22 to the total area of ​​the first electrode tab 22 is too high, resulting in a small effective conductive area and reduced current carrying capacity. If the S1 / S ratio is too small, the proportion of the total area of ​​the first through-hole 221 is too low, leading to insufficient electrolyte wetting channel area, low electrolyte penetration into the cell 20, inadequate wetting of the internal area of ​​the cell 20, limited formation gas exhaust channel area, large gas retention, increased gas resistance, and reduced electrode uniformity. Therefore, by controlling the S1 / S ratio within the range of 5% to 45%, it is possible to ensure that the first electrode tab 22 has sufficient effective conductive area to ensure good current carrying capacity, while also providing sufficient channel area for electrolyte wetting and formation gas exhaust, thereby improving wetting uniformity and electrode uniformity.

[0043] For example, the S1 / S ratio can be 5%, 7%, 9%, 11%, 14%, 17%, 21%, 25%, 29%, 33%, 37%, 40%, 43%, 45%, etc., or a value within the range of any two of the above values.

[0044] In some embodiments, the diameter d1 of the first through hole 221 is in the range of 0.1μm≤d1≤500μm. Along the second direction Y, the density of the first through holes 221 near the center of the first electrode tab 22 is greater than the density of the first through holes 221 located on both sides of the center of the first electrode tab 22. The diameter d1 of the first through hole 221 is the maximum size of the first through hole 221.

[0045] Along the second direction Y, the first electrode tab 22 has a width extending along the second direction Y, the middle position of the first electrode tab 22 along the second direction Y is the center of the first electrode tab 22, and the two sides of the center are areas extending to the two edges respectively.

[0046] The density refers to the number of first through holes 221 per unit area or the distribution frequency of first through holes 221 per unit length. The density of first through holes 221 near the center of the first electrode tab 22 is greater than that on both sides of the center. In some embodiments, the first through holes 221 are clustered around the central region of the first electrode tab 22 and sparse towards the two side edges, forming a radially gradual distribution.

[0047] If d1 is too large, the diameter of the first through-hole 221 will be too large, resulting in a small effective conductive area for the tab and a decrease in current carrying capacity. If d1 is too small, the diameter of the first through-hole 221 will be too small, increasing the permeation resistance of the electrolyte through the through-hole, reducing the electrolyte wetting efficiency, increasing the resistance to gas discharge during the formation stage through the tiny through-hole, hindering venting, and increasing the amount of gas retained inside the cell 20. Therefore, by controlling d1 within the range of 0.1μm to 500μm, both the strength and conductive area of ​​the first tab 22 can be ensured, while also ensuring smooth flow of electrolyte and gas within the through-hole, improving wetting and venting efficiency.

[0048] For example, d1 can be 0.1μm, 0.5μm, 1.5μm, 5μm, 15μm, 35μm, 70μm, 120μm, 180μm, 250μm, 330μm, 400μm, 460μm, 500μm, etc., or a value within the range of any two of the above values.

[0049] Regarding the measurement of d1, the battery can be removed to expose the first electrode tab 22, and the aperture of the first through hole 221 can be measured using an optical microscope.

[0050] The first through holes 221 are radially distributed around the center of the first electrode tab 22. The central region has a high density and a large number of through holes per unit area, resulting in high efficiency of electrolyte and gas passage in the central region. The dense through holes help improve the central region of the cell 20, which is difficult to wet, and also allow gas inside the cell 20 to pass through the through holes smoothly. The density of the through holes on both sides is low, and the current density on both sides is relatively low. Maintaining sufficient conductive area helps reduce the overall electrode tab temperature rise. As a result, the uniformity of battery wetting and charge / discharge performance are further improved.

[0051] In some embodiments, an insulating protective layer 30 is attached to at least one side of the first electrode tab 22 along the third direction Z, the insulating protective layer 30 covers the first solder area 24, and a second through hole 31 is provided on the insulating protective layer 30.

[0052] The insulating protective layer 30 can be a thin film structure with electrical insulation and high temperature resistance. The insulating protective layer 30 can be a colloid or an adhesive film. For example, the insulating protective layer 30 can be made of polymer insulating materials such as polyimide film, polyethylene terephthalate film, polyethylene naphthalate film, or polyphenylene sulfide film.

[0053] The insulating protective layer 30 is adhered to at least one side surface of the first tab 22 along the third direction Z by an acrylic adhesive or a silicone adhesive, that is, it is adhered to one or two outer surfaces of the tab assembly along the third direction Z.

[0054] The insulating protective layer 30 covers the first soldering area 24, meaning that the projection area of ​​the insulating protective layer 30 on the first electrode tab 22 at least covers the projection area of ​​the first soldering area 24 on the first electrode tab 22. The second through hole 31 is a hole structure that penetrates the thickness direction of the insulating protective layer 30.

[0055] The insulating protective layer 30 covers the first solder area 24, providing insulation protection for the first solder area 24 and preventing it from contacting other conductive components inside the battery, thus reducing the risk of internal short circuits and improving battery safety performance. A second through-hole 31 is provided on the insulating protective layer 30, ensuring that while covering the first solder area 24, the insulating protective layer 30 does not obstruct the electrolyte wetting channel and formation venting channel of the first through-hole 221 on the first electrode tab 22. Electrolyte can sequentially enter the cell 20 through the second through-hole 31 and the first through-hole 221, and formation gas can sequentially exit the cell 20 through the first through-hole 221 and the second through-hole 31, ensuring wetting and venting efficiency and maintaining battery charge / discharge performance.

[0056] In some embodiments, the diameter d2 of the second through hole 31 is greater than or equal to the diameter d1 of the first through hole 221; and / or, along the third direction Z, the projection of the second through hole 31 at least partially overlaps with the projection of the first through hole 221 on the outermost first tab 22; and / or, the second through hole 31 is located outside the coverage area of ​​the insulating protective layer 30 covering the first solder area 24.

[0057] Along the third direction Z, after multiple layers of first electrode tabs 22 are stacked to form a first electrode tab cluster, the outermost layer of first electrode tabs 22 along the third direction Z is the outermost first electrode tab 22. When viewed along the third direction Z, the projection area of ​​the second through hole 31 intersects with the projection area of ​​the first through hole 221 on the outermost first electrode tab 22, that is, the second through hole 31 and the first through hole 221 form a through channel along the third direction Z.

[0058] The second through hole 31 is located outside the area covered by the insulating protective layer 30 covering the first solder area 24, that is, the distribution area of ​​the second through hole 31 on the insulating protective layer 30 avoids the area covering the first solder area 24.

[0059] Regarding the measurement of d2, the battery can be removed to expose the first electrode tab 22, and the aperture of the first through hole 221 can be measured using an optical microscope.

[0060] d2 is greater than or equal to d1, so that the diameter of the second through hole 31 is not less than the diameter of the first through hole 221, thus preventing the second through hole 31 of the insulating protective layer 30 from blocking the first through hole 221 of the first electrode tab 22, and ensuring smooth flow of electrolyte and gas between the first through hole 221 and the second through hole 31.

[0061] The projection of the second through hole 31 at least partially overlaps with that of the outermost first through hole 221. The two through holes form a continuous channel extending in the third direction Z. Electrolyte and gas can flow directly along this channel. The channel has good continuity, low flow resistance, and further improves wetting efficiency and exhaust efficiency.

[0062] The second through hole 31 is located outside the coverage area and avoids the first solder area 24, ensuring the integrity of the insulation protection on the first solder area 24 and further reducing the risk of internal short circuit in the battery.

[0063] In some embodiments, an insulating protective layer 30 is attached to both sides of the first electrode tab 22 along the third direction Z; the portions of the insulating protective layers 30 on both sides extending beyond the edge of the first electrode tab 22 along the second direction Y are bonded together to form a first bonding area 30a, and a second through hole 31 is located outside the first bonding area 30a; and / or, the insulating protective layers 30 on both sides are bonded to the two sides of the cell body 21 along the third direction Z to form a second bonding area 30b, and a second through hole 31 is located outside the second bonding area 30b.

[0064] The first bonding area 30a is the area formed by bonding the portions of the two insulating protective layers 30 on both sides of the multilayer first electrode tab 22 along the third direction Z to each other along the second direction Y, which extend beyond the edge of the first electrode tab 22. The first bonding area 30a is located on the side of the first electrode tab 22 along the second direction Y.

[0065] The second bonding area 30b is the area formed by the two insulating protective layers 30 extending towards the cell body 21 on both sides and bonding with the two sides of the cell body 21 along the third direction Z. The second bonding area 30b is located in the transition area between the first tab 22 and the cell body 21.

[0066] Insulating protective layers 30 are attached to both sides of the first tab 22 along the third direction Z, and the first solder area 24 is covered by insulating protective layers 30 on both sides along the third direction Z. The first solder area 24 obtains double-sided insulation protection, which is more comprehensive and further reduces the risk of internal short circuit in the battery.

[0067] The portions of the insulating protective layers 30 extending beyond the edge of the first electrode lug 22 are bonded together to form a first bonding area 30a. The first bonding area 30a wraps and fixes the multi-layer first electrode lug 22 along both sides of the second direction Y, making the insulating protective layers 30 more firmly fixed, preventing peeling, and improving insulation reliability.

[0068] The second through hole 31 is located outside the first bonding area 30a to avoid affecting the bonding strength between the insulating protective layers 30 by opening through holes in the first bonding area 30a.

[0069] The insulating protective layers 30 on both sides are bonded to the main body of the battery cell 21 to form a second bonding area 30b, which improves the fixation reliability of the insulating protective layer 30. The second through hole 31 is located outside the second bonding area 30b to avoid affecting the bonding strength between the insulating protective layer 30 and the main body of the battery cell 21, and to ensure the continuous protective stability of the insulating protective layer 30.

[0070] In some embodiments, each layer of first electrode tab 22 is provided with a first through hole 221, and the first through holes 221 on the multiple layers of first electrode tab 22 at least partially overlap.

[0071] Each layer of the first electrode tab 22 is provided with a first through hole 221, that is, each layer of the first electrode tab 22 constituting the multi-layer first electrode tab has a first through hole 221 extending along the thickness direction. The first through holes 221 on the multi-layer first electrode tab 22 at least partially overlap, that is, when viewed along the third direction Z, the projections of the first through holes 221 on the plane of the first electrode tab 22 of adjacent layers overlap, and the multi-layer first through holes 221 form a continuous channel extending along the third direction Z.

[0072] Each layer of the first tab 22 is provided with a first through hole 221, providing an independent channel for electrolyte wetting and formation venting. The increased number of channels increases the number of electrolyte penetration paths from the tab area into the cell 20, improving penetration efficiency and further enhancing the uniformity of wetting in all areas of the cell 20. During the formation stage, each layer of tabs has venting channels, increasing gas venting paths and further reducing gas retention. The multiple layers of first through holes 221 at least partially overlap, forming a continuous channel along the third direction Z. Electrolyte and gas can flow directly from one side of the tab assembly to the other along this continuous channel, resulting in a short flow path, low flow resistance, further improved wetting and venting efficiency, and further enhanced battery charge / discharge performance.

[0073] In some embodiments, oblique cuts 22a are respectively provided at the two corners of the multilayer first electrode tab 22 away from the head of the cell body 21 along the second direction Y.

[0074] The end of the multilayer first electrode 22 away from the cell body 21 is the free end of the multilayer first electrode 22 extending out of the cell body 21 along the first direction X, and this free end is the electrode head.

[0075] Along the second direction Y, the tab head has two corner positions, which are the corner positions where the two side edges and the top edge intersect. The oblique cut 22a is a bevel or chamfer structure formed by cutting off part of the tab material obliquely at the corner position of the tab head. The oblique cut 22a can be formed by die cutting or stamping.

[0076] A slanted cut 22a is provided at the corners on both sides of the tab head. The sharp right angle of the tab head is removed, and a smooth slant is formed at the corner. This reduces the risk of the sharp right angle on both sides of the tab head piercing the separator, reduces the risk of internal short circuit in the battery, and further improves the battery safety performance.

[0077] In some embodiments, the electrolyte within the membrane housing 10 comprises vinylene carbonate, 1,3-propanesulfonate lactone, and 1,3-propenesulfonate lactone. The mass percentage (A) of vinylene carbonate in the total electrolyte mass content is 0.01% to 2%. The combined mass content (B) of 1,3-propanesulfonate lactone and 1,3-propenesulfonate lactone in the total electrolyte mass content is 0.1% to 5%.

[0078] Ethylene carbonate is an organic film-forming additive that can be reduced and decomposed on the negative electrode surface to form a stable solid electrolyte interfacial film. 1,3-propanesulfonate lactone and 1,3-propenesulfonate lactone are sulfur-containing electrolyte additives that can form sulfur-containing interfacial films on the positive and negative electrode surfaces, improving interfacial stability.

[0079] If A is too high, the vinylene carbonate content is too high, resulting in an excessively thick solid electrolyte interfacial film, increased film impedance, increased lithium-ion migration resistance, increased battery internal resistance, and increased heat generation during high-rate discharge. If A is too low, the vinylene carbonate content is too low, leading to incomplete film formation on the negative electrode surface, low solid electrolyte interfacial film coverage, increased side reactions between the negative electrode and electrolyte, and intensified reduction and decomposition of the electrolyte on the negative electrode surface, resulting in increased gas generation during the formation stage and subsequent cycling. Therefore, by controlling A within the range of 0.01% to 2%, a complete solid electrolyte interfacial film with appropriate impedance can be formed, while the gas generation during formation and cycling can be reduced by suppressing side reactions between the negative electrode and electrolyte, thereby improving battery interface stability and extending cycle life.

[0080] For example, A can be 0.01%, 0.03%, 0.07%, 0.12%, 0.25%, 0.45%, 0.7%, 0.95%, 1.2%, 1.45%, 1.65%, 1.85%, 1.95%, 2%, or a value within the range of any two of the above values.

[0081] If B is too high, the total content of 1,3-propanesulfonyl lactone and 1,3-propenesulfonyl lactone will be too high, leading to excessive growth of the sulfur-containing interfacial film, excessive film thickness, significantly increased interfacial impedance, and decreased high-rate performance of the battery. If B is too low, the content of sulfur-containing additives will be too low, resulting in insufficient formation of the sulfur-containing interfacial film on the positive and negative electrode surfaces, inadequate interfacial protection, and intensified redox decomposition of the electrolyte on the positive and negative electrode surfaces at high temperatures, increased gas production, and decreased high-temperature cycle stability. Therefore, by controlling B within the range of 0.1% to 5%, an effective sulfur-containing interfacial protective film can be formed, and the gas production during formation and cycling can be reduced by inhibiting the decomposition reaction of the electrolyte at high temperatures, thereby improving interfacial stability and high-temperature cycle performance.

[0082] For example, B can be 0.1%, 0.2%, 0.4%, 0.7%, 1.1%, 1.6%, 2.2%, 2.9%, 3.5%, 4.0%, 4.4%, 4.7%, 4.9%, 5.0%, or a value within the range of any two of the above values.

[0083] The measurements of A and B can be obtained by quantitative analysis of the content of each additive in the electrolyte using gas chromatography or liquid chromatography.

[0084] With this configuration, the combined action of vinylene carbonate, 1,3-propanesulfonate lactone, and 1,3-propenesulfonate lactone in the electrolyte stabilizes the electrode / electrolyte interface through the solid electrolyte interfacial film and the sulfur-containing interfacial film. This reduces side reactions between the electrode and the electrolyte, and decreases gas production during the formation and cycling stages. The reduced gas production decreases the total amount of gas that needs to be discharged during the formation stage, correspondingly reducing the required exhaust channel area for the first through-hole 221 on the first electrode tab 22. This allows for a reduction in the number of first through-holes 221 and / or a smaller aperture, thus lowering the area ratio occupied by through-holes on the first electrode tab 22. This increases the effective conductive cross-sectional area of ​​the first electrode tab 22, improves the tab's current-carrying capacity, reduces the current density in the tab region during high-rate discharge, and decreases heat generation. Meanwhile, the number of through holes on the first electrode tab 22 is reduced and / or the hole diameter is reduced, the structural integrity of the first electrode tab 22 is enhanced, the stress concentration is reduced, the mechanical strength of the electrode tab is improved, the tear resistance and fracture resistance of the electrode tab during bending, vibration or welding are improved, and the structural reliability and service life of the electrode tab area are improved.

[0085] In some embodiments, the battery cell 20 includes a positive electrode, a negative electrode, and a separator. The negative electrode contains silicon-carbon material, and the thickness of the positive electrode ranges from 45 μm to 70 μm, and the thickness of the negative electrode ranges from 45 μm to 70 μm.

[0086] The positive electrode sheet is a metal foil sheet with a positive electrode active material layer coated on its surface. The positive electrode active material layer may contain one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, ternary lithium, lithium iron phosphate, or lithium manganese oxide.

[0087] The negative electrode is a metal foil coated with a negative electrode active material layer. The negative electrode contains silicon-carbon material, which is a composite material of silicon and carbon. The mass content of silicon can be 5% to 60%. The carbon matrix in the silicon-carbon material can be one or more of graphite, mesophase carbon microspheres or hard carbon.

[0088] The separator is a polyolefin film with a microporous structure, which is placed between the positive electrode and the negative electrode. The separator is used to prevent the positive and negative electrodes from coming into direct contact while allowing lithium ions to pass through.

[0089] The thicknesses of the positive and negative electrodes are the total thicknesses of the positive and negative electrodes in the direction perpendicular to their respective large surfaces, including the thickness of the current collector and the thickness of the active material layers coated on both sides.

[0090] If the thickness of the positive or negative electrode is too large, the solid-state diffusion path of lithium ions within the electrode is long, resulting in high diffusion resistance, increased internal resistance of the battery, increased polarization during high-rate discharge, and increased heat generation. Furthermore, the thicker electrode has a greater electrolyte wetting depth, reducing wetting uniformity. Conversely, if the thickness of the positive or negative electrode is too small, the amount of active material coated per unit area is less, reducing battery energy density. Additionally, thin electrodes lack mechanical strength, making them prone to breakage during processing and reducing production efficiency. Therefore, by controlling the thickness of the positive and negative electrodes within the range of 45μm to 70μm, it is possible to shorten the migration path of lithium ions within the electrode to reduce battery internal resistance and heat generation during high-rate discharge, while maintaining sufficient active material loading and mechanical strength, thus achieving a balance between battery energy density and processing performance.

[0091] For example, the thickness of the positive electrode can be 45μm, 47μm, 49μm, 52μm, 55μm, 58μm, 60μm, 62μm, 64μm, 66μm, 68μm, 70μm, or a value within any two of the above values.

[0092] The thickness of the negative electrode can be 45μm, 47μm, 49μm, 52μm, 55μm, 58μm, 60μm, 62μm, 64μm, 66μm, 68μm, 70μm, or a value within any two of the above ranges.

[0093] To measure the thickness of the electrode, a micrometer can be used to measure the thickness at multiple locations on the electrode and then the average value is taken.

[0094] In some embodiments, the membrane shell 10 further includes a second sealing edge 12 opposite to the first sealing edge 11 along the first direction X, and the battery cell 20 further includes multiple layers of second electrode tabs extending from the battery cell body 21 toward the second sealing edge 12. The multiple layers of second electrode tabs are stacked along the third direction Z and welded to the second adapter tab 25 to form a second solder area. The end of the second adapter tab 25 away from the second electrode tab extends out of the membrane shell 10 via the second sealing edge 12, and a third through hole is provided on at least one layer of the second electrode tab.

[0095] The second sealing edge 12 is a sealing structure formed by hot-pressing the edge of the membrane shell 10 opposite to the first sealing edge 11 along the first direction X.

[0096] The second tab is a multilayer second tab foil extending from the cell body 21 toward the second sealing edge 12. The second tab is formed by extending the portion of the current collector of the electrode plate with the opposite polarity to that of the first tab 22 without being coated with active material.

[0097] The second adapter tab 25 is a metal conductive component that is welded to the second tab sheet. The material can be copper, aluminum, nickel or a corresponding alloy. One end of the second adapter tab 25 is welded to the stacked multilayer second tab sheets to form a second solder area, and the other end extends along the first direction X and protrudes out of the membrane shell 10 through the second sealing edge 12.

[0098] The third through hole is a hole that penetrates the thickness direction of the second electrode lug and can be formed by punching, laser drilling, or other methods.

[0099] The membrane shell 10 includes a first sealing edge 11 and a second sealing edge 12 opposite to each other along the first direction X. A first adapter tab 23 extends from the first sealing edge 11, and a second adapter tab 25 extends from the second sealing edge 12. The positive and negative tabs are located on both sides of the pouch battery, forming an opposite-side tab design, which increases the heat diffusion distance between the positive and negative tabs and helps reduce the temperature rise in the tab area. At the same time, the opposite-side tabs increase the width of each single tab, making the width of the first tab plate 22 and the second tab plate larger, increasing the current flow area, reducing the current density, further reducing the heat generated by the tabs, further reducing the battery temperature rise, extending the cycle life, and improving the charge-discharge rate. At least one second tab plate is provided with a third through hole, which provides an additional wetting channel for the electrolyte to enter the cell 20 from the second tab plate side. The electrolyte can enter the cell 20 from both sides of the battery, further shortening the wetting path and further improving the wetting uniformity inside the cell 20. The third through hole also provides an exhaust path for the gas generated near the second tab area of ​​the cell 20 during the formation stage. The gas can be discharged from both sides, further reducing the amount of gas retention, further reducing gas resistance, further improving the consistency of the electrode, and further improving the battery charge and discharge performance.

[0100] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A soft-pack battery, characterized in that, include: The membrane shell (10) includes a first sealing edge (11); An electrode assembly is disposed within the membrane housing (10). The electrode assembly includes a battery cell (20) and a first adapter tab (23). The battery cell (20) includes a battery cell body (21) and multiple layers of first tab sheets (22) extending from the battery cell body (21) toward the first sealing edge (11). The multiple layers of first tab sheets (22) are stacked along a third direction (Z) to form a first tab cluster and are welded to the first adapter tab (23) to form a first solder area (24). Along a first direction (X) parallel to the extension direction of the first tab sheet (22), the end of the first adapter tab (23) away from the first tab sheet (22) extends out of the membrane housing (10) via the first sealing edge (11). Along the second direction (Y), the size of the first tab (22) is D, and the size of the soft-pack battery is L, satisfying 0.5≤D / L<1. At least one layer of the first tab (22) is provided with a first through hole (221), and the first direction (X), the second direction (Y) and the third direction (Z) are perpendicular to each other.

2. The soft-pack battery according to claim 1, characterized in that, The first through hole (221) is located outside the first solder area (24). Along the third direction (Z), the first through hole (22) is provided on at least one side of the first electrode cluster center of the multilayer first electrode tabs.

3. The soft-pack battery according to claim 1, characterized in that, Along the third direction (Z), the ratio of the total projected area S1 of the first through hole (221) to the projected area S of the first tab (22) is in the range of 5% ≤ S1 / S ≤ 45%.

4. The soft-pack battery according to claim 1, characterized in that, The diameter d1 of the first through hole (221) is in the range of 0.1μm≤d1≤500μm; And / or, along the second direction (Y), the density of the first through holes (221) on the first tab (22) near the center of the first tab (22) is greater than the density of the first through holes (221) on both sides of the center of the first tab (22).

5. The pouch cell battery according to any one of claims 1-4, characterized in that, An insulating protective layer (30) is attached to at least one side of the first electrode tab (22) along the third direction (Z), the insulating protective layer (30) covers the first solder area (24), and a second through hole (31) is provided on the insulating protective layer (30).

6. The soft-pack battery according to claim 5, characterized in that, The diameter d2 of the second through hole (31) is greater than or equal to the diameter d1 of the first through hole (221); And / or, along the third direction (Z), the projection of the second through hole (31) at least partially overlaps with the projection of the first through hole (221) on the outermost first tab (22); And / or, the second through hole (31) is located in the area where the insulating protective layer (30) does not cover the first solder area (24).

7. The soft-pack battery according to claim 5, characterized in that, The first electrode tab (22) has the insulating protective layer (30) attached to both sides along the third direction (Z); The insulating protective layers (30) on both sides are bonded together along the second direction (Y) beyond the edge of the first electrode tab (22) to form a first bonding area (30a), and the second through hole (31) is located outside the first bonding area (30a); and / or, the insulating protective layers (30) on both sides are bonded to the two sides of the battery cell body (21) along the third direction (Z) to form a second bonding area (30b), and the second through hole (31) is located outside the second bonding area (30b).

8. The pouch cell battery according to any one of claims 1-4, characterized in that, Each layer of the first electrode tab (22) is provided with the first through hole (221), and the first through holes (221) on the multiple layers of the first electrode tab (22) at least partially overlap.

9. The pouch cell battery according to any one of claims 1-4, characterized in that, The first electrode tab (22) of the multilayer is provided with oblique cuts (22a) at the two corners along the second direction (Y) away from the head of the battery cell body (21).

10. The pouch cell according to any one of claims 1-4, characterized in that, The membrane shell (10) further includes a second sealing edge (12) opposite to the first sealing edge (11) along the first direction (X). The battery cell (20) further includes multiple layers of second electrode tabs extending from the battery cell body (21) toward the second sealing edge (12). The multiple layers of second electrode tabs are stacked along the third direction (Z) and welded with the second adapter tab (25) to form a second solder area. The end of the second adapter tab (25) away from the second electrode tab extends out of the membrane shell (10) via the second sealing edge (12). At least one layer of the second electrode tab is provided with a third through hole.

Images