Square-shaped battery cell and battery pack

Abstract

The utility model relates to battery technical field discloses a square electric core and battery package. Among them, square electric core includes: package shell, pole group subassembly, assembles in package shell, and pole group subassembly includes square pole group and the insulating film that wraps in square pole group outside, and pole group subassembly has bottom surface and the side of surrounding bottom surface, and the side includes a pair of big side surface along X direction opposite arrangement and a pair of narrow side surface along Y direction opposite arrangement, sealing band, covers on the bottom surface and narrow side surface of pole group subassembly to seal the gap that insulating film after folding produces. The utility model discloses through setting sealing band on the bottom surface and narrow side surface of pole group subassembly, can seal the gap that insulating film produces in the wrapping process to this place, blocks the path that the powder particle of square pole group passes through the gap on insulating film and moves to package shell, avoids that square electric core's self -discharge is too big and the corrosion risk.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, specifically to a square battery cell and battery pack. Background Technology

[0002] Square cells are an important type of battery cell widely used in the current battery industry. They are usually packaged in aluminum or steel shells and are rectangular in shape. They occupy a key market position due to their mature production process and outstanding comprehensive performance.

[0003] To improve the safety of prismatic battery cells, an insulating film is typically wrapped around the outer side of the internal electrode assembly to isolate it from the cell's casing. To prevent the insulating film from detaching from the electrode assembly, it is heat-fused to secure the film bent to the narrow side of the assembly. However, while this method effectively secures the insulating film to the electrode assembly, gaps can easily appear near the bottom corners of the electrode assembly due to insufficient adhesion. Therefore, in cases of slight or localized powder shedding from the electrode assembly, powder particles may seep through these gaps along with the electrolyte and adhere to the casing, leading to excessive self-discharge and corrosion risk in the prismatic battery cell. Utility Model Content

[0004] In view of this, the present invention provides a square battery cell and battery pack to solve the problem of excessive self-discharge and corrosion of square battery cells caused by gaps in the insulating film at the bottom corners of the electrode assembly.

[0005] In a first aspect, this utility model provides a square battery cell, comprising: Encapsulation housing; An electrode assembly is assembled within the encapsulation housing. The electrode assembly includes a square electrode assembly and an insulating film wrapped around the square electrode assembly. The electrode assembly has a bottom surface and side surfaces surrounding the bottom surface. The side surfaces include a pair of large side surfaces arranged opposite each other along the X direction and a pair of narrow side surfaces arranged opposite each other along the Y direction. A sealing tape is applied to the bottom and narrow sides of the electrode assembly to seal any gaps created when the insulating film is bent.

[0006] Beneficial Effects: This invention, by placing sealing tape on the bottom and narrow sides of the electrode assembly, effectively seals the gaps created during the wrapping process of the insulating film. This effectively blocks the migration path of powder particles from the square electrode assembly to the packaging shell through the gaps in the insulating film, preventing internal micro-short circuits caused by the accumulation of powder particles forming a "square electrode assembly-powder particles-packaging shell" conductive path. This, in turn, avoids excessive self-discharge and corrosion risks in the square battery cell. Simultaneously, the sealing tape also prevents external impurities from entering the square electrode assembly, reducing the safety risks of cell bulging, leakage, and even fire from the source. Furthermore, the sealing tape enhances the adhesion stability of the insulating film at the connection points on the bottom and narrow sides, reducing the probability of cyclic deformation of the square electrode assembly or the insulating film peeling or falling off at corners during assembly and transportation. This ensures that the insulating film reliably isolates the square electrode assembly from the packaging shell, guaranteeing the continuous effectiveness of the square battery cell's insulation performance.

[0007] In one alternative embodiment, the number of sealing strips is one pair, and the pair of sealing strips are located on opposite sides of the pole assembly in the Y direction.

[0008] Beneficial effects: By setting a pair of sealing strips on opposite sides of the electrode assembly in the Y direction, the gaps created by the insulating film wrapping on the corresponding narrow sides and bottom surface can be precisely sealed. This also specifically blocks the migration path of square electrode powder particles to the packaging shell in this area, avoiding the formation of local conductive paths that could cause internal micro-short circuits. At the same time, it effectively blocks external impurities from entering through the gaps on the narrow sides and bottom surface, further reducing the safety risks of cell bulging and leakage. It also enhances the adhesion stability of the insulating film at the connection between the narrow sides and bottom surface, reducing the possibility of the insulating film peeling or falling off at this critical corner during repeated use or assembly and transportation. This ensures reliable isolation of the square electrode assembly from the packaging shell by the insulating film, guaranteeing the stability of the cell's insulation performance and safety in use.

[0009] In one alternative embodiment, the sealing strip includes a pair of sub-sealing strips, which are located on the same side in the Y direction and are spaced apart or continuous in the X direction.

[0010] Beneficial effects: When continuous setting is used, a seamless sealing structure can be formed on the insulating film, effectively blocking the penetration path of powder particles and greatly improving the sealing reliability. It is suitable for precision equipment or harsh working conditions with extremely high sealing performance requirements. When interval setting is selected, the amount of sealing tape material used can be reduced while ensuring the basic sealing effect, thus reducing production costs.

[0011] In one alternative implementation, along the X direction, the edges of the pair of sub-sealing strips extend away from each other to the adjacent large side surface, or, along the X direction, the edges of the pair of sub-sealing strips away from each other coincide with the edges of the adjacent narrow side surface and the bottom surface.

[0012] Beneficial effects: When the edges of a pair of sub-sealing tapes, away from each other, overlap with the edges of their adjacent narrow sides and bottom surfaces, they can effectively cover gaps at the edges, reducing the possibility of leakage. Extending the edges of the pair of sub-sealing tapes away from each other onto their adjacent large sides increases the contact area between the sub-sealing tapes and the insulating film, improving the connection stability between the two and reducing the possibility of the sub-sealing tapes detaching from the insulating film.

[0013] In one optional embodiment, in the Y direction, the sum of the widths of the pair of sub-sealing strips located on the same side in the X direction is a, and the value of a is in the range of: 1 / 2 the width of the square pole group ≤ a ≤ 1 / 2 the width of the square pole group + 50 mm, wherein the width of the square pole group is the dimension of the square pole group in the X direction.

[0014] Beneficial effects: This utility model controls the total width 'a' of the two sub-sealing strips located on the same side to be between 1 / 2 square pole group width ≤ a ≤ 1 / 2 square pole group width + 50mm. This ensures that the sealing strip has sufficient coverage area to seal the gaps of the insulating film on the narrow side and bottom surface, avoids material waste caused by excessive sealing strip width, and also prevents the sealing strip from excessively encroaching on the internal space of the cell, affecting the compact arrangement of the square pole group and the overall energy density of the cell.

[0015] In one alternative embodiment, along the Z direction, the length of the sealing strip on the narrow side is b, where b ranges from 35mm to 50mm; and / or, along the Y direction, the length of the sealing strip on the bottom surface is c, where c ranges from 35mm to 50mm.

[0016] Beneficial effects: This utility model controls the length b of the sealing strip on the narrow side to between 35mm≤b≤50mm, and the length c of the sealing strip on the bottom surface to between 35mm≤c≤50mm. This ensures that the sealing strip has sufficient coverage area to seal the gaps of the insulating film on the narrow side and bottom surface, avoids material waste caused by excessive sealing strip length, and also prevents the sealing strip from excessively encroaching on the internal space of the battery cell, affecting the compact arrangement of the square electrode group and the overall energy density of the battery cell.

[0017] In one optional embodiment, the thickness of the sealing strip is d, and the value of d ranges from 30μm≤d≤50μm.

[0018] Beneficial effects: In this embodiment, the thickness d of the sealing strip is controlled between 30μm≤d≤50μm. On the one hand, this ensures that the sealing strip has sufficient structural strength and integrity, and can closely fit the bottom surface, narrow side surface and corner area of ​​the electrode assembly to form a continuous and uniform protective layer. On the other hand, it avoids the sealing strip from excessively occupying the limited space inside the battery, ensuring that the square electrode assembly can be compactly arranged to maintain the battery's high energy density. At the same time, it can also reduce production costs while ensuring the protective effect.

[0019] In one alternative embodiment, the sealing tape is an insulating tape or an insulating coating.

[0020] Beneficial effects: Using insulating tape as a sealing strip allows for quick and easy application and fixation due to its inherent adhesive layer, eliminating the need for additional glue mixing or curing time. This significantly simplifies the assembly process and improves production efficiency. Using an insulating coating as a sealing strip, after curing, forms a tightly bonded "thin-film protective layer" with the insulating film, eliminating noticeable seams and effectively blocking the movement path of the square electrode powder particles. Furthermore, the thickness of the insulating coating can be flexibly controlled according to requirements, without occupying excessive internal space. In addition, compared to insulating tape, the insulating coating has better compatibility with the insulating film, eliminating the risk of peeling due to material differences.

[0021] In one optional embodiment, the sealing strip is an insulating coating, and the insulating coating is made of a dry-curing thermoplastic material.

[0022] Beneficial effects: Thermoplastic materials possess both excellent electrical insulation and a certain degree of flexibility. They can reliably block unnecessary current conduction between the square electrode assembly and the packaging shell, preventing short circuits. Furthermore, they can adapt to the slight volume expansion and contraction of the square electrode assembly during cell charging and discharging, avoiding cracking and peeling issues common in rigid coatings and ensuring long-term insulation and sealing. Secondly, the drying-curing method is simple and efficient, eliminating the need for complex high-temperature sintering or prolonged cross-linking reactions, making it more suitable for the rapid pace of large-scale cell production.

[0023] Secondly, this utility model also provides a battery pack, comprising: Box; Multiple of the aforementioned square battery cells are arranged side by side inside the casing.

[0024] Beneficial effects: The battery pack of this utility model includes the square battery cell as described above, and has all the beneficial technical effects of the square battery cell, which will not be repeated here. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of this utility model 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 this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of an insulating film in the unfolded state in the prior art; Figure 2 This is a schematic diagram of the square pole group according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the square pole group of an embodiment of the present invention from another perspective.

[0027] Figure 4 This is a structural schematic diagram of the square pole group according to another perspective of an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures: Existing technology: 1' Bottom film; 2' Side film; 201' Large surface of the film; 2011' Side folded surface; 202' Bottom folded surface; 3' First fold line; 4' Second fold line; 5' Third fold line; This application: 1. Bottom surface; 2. Side surface; 201. Large side surface; 202. Narrow side surface; 3. Insulating film; 4. Sealing tape. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0030] like Figure 1As shown, in the unfolded state, the insulating film includes a bottom film 1' and a side film 2' located around the bottom film 1'. The side film 2' includes a pair of large film surfaces 201' and a pair of bottom folded surfaces 202'. The pair of large film surfaces 201' are located on opposite sides of the bottom film 1' in the X direction, and a first fold line 3' is provided at the connection between the large film surfaces 201' and the bottom film 1'. The pair of bottom folded surfaces 202' are located on opposite sides of the bottom film 1' in the Y direction, and a second fold line 4' is provided at the connection between the bottom folded surfaces 202' and the bottom film 1'. The large film surfaces 201' are provided with side folded surfaces 2011' on opposite sides in the Y direction, and a third fold line 5' is provided at the connection between the side folded surfaces 2011' and the large film surfaces 201'. In the wrapped state, the bottom film 1' is positioned opposite to the bottom surface of the square electrode assembly, the large surface 201' of the film is positioned opposite to the large side surface of the square electrode assembly through the first fold line 3', and the bottom folded surface 202' and the side folded surface 2011' located on the same side are positioned opposite to the narrow side surface of the square electrode assembly through the second fold line 4' and the third fold line 5' respectively.

[0031] To secure the insulating film to the periphery of the square electrode assembly, a heat-fusion method is typically used to connect the bottom folded surface 202' to the side folded surface 2011' located on the same side. However, since currently only the bottom folded surface 202' and the side folded surface 2011' located in the middle area of ​​the narrow side of the square electrode assembly are heat-fused, gaps remain on both sides of the narrow side of the square electrode assembly near the bottom surface. Therefore, when the square electrode assembly experiences slight or localized powder shedding, powder particles risk leaking out through the gaps along with the free electrolyte, causing contact with the packaging shell, leading to excessive self-discharge of the cell and corrosion risk.

[0032] Based on this, the present invention provides a novel square battery cell. Specifically, the following describes... Figures 2 to 4 This describes embodiments of the present invention. For ease of description below, as follows... Figures 2 to 4 As shown, a spatial rectangular coordinate system is established: the height direction of the square battery cell is denoted as the Z direction, the length direction of the square battery cell is denoted as the Y direction, and the width direction (or thickness direction) of the square battery cell is denoted as the X direction.

[0033] According to embodiments of the present invention, on the one hand, such as Figure 2 As shown, a square battery cell is provided, comprising: a package housing, an electrode assembly, and a sealing strip 4; Specifically, the electrode assembly is assembled inside the encapsulation housing. The electrode assembly includes a square electrode assembly and an insulating film 3 wrapped around the square electrode assembly. The electrode assembly has a bottom surface 1 and side surfaces 2 surrounding the bottom surface 1. The side surfaces 2 include a pair of large side surfaces 201 arranged opposite each other in the X direction and a pair of narrow side surfaces 202 arranged opposite each other in the Y direction. A sealing strip 4 covers the bottom surface 1 and the narrow side surfaces 202 of the electrode assembly to seal the gaps created by bending the insulating film 3.

[0034] This embodiment of the invention uses a sealing strip 4 on the bottom surface 1 and narrow side surface 202 of the electrode assembly. On one hand, this seals the gaps created by the insulating film 3 during the wrapping process, effectively blocking the migration path of powder particles from the square electrode assembly through the insulating film 3 to the packaging shell. This prevents internal micro-short circuits caused by the accumulation of powder particles forming a conductive path of "square electrode assembly-powder particles-packaging shell," thus avoiding excessive self-discharge and corrosion risks in the square battery cell. Simultaneously, the sealing strip 4 prevents external impurities from entering the square electrode assembly, reducing the safety risks of cell bulging, leakage, and even fire from the source. On the other hand, the sealing strip 4 enhances the adhesion stability of the insulating film 3 at the connection between the bottom surface 1 and the narrow side surface 202, reducing the probability of cyclic deformation of the square electrode assembly or the insulating film 3 peeling or falling off at corners during assembly and transportation. This ensures that the insulating film 3 reliably isolates the square electrode assembly from the packaging shell, guaranteeing the continuous effectiveness of the square battery cell's insulation performance.

[0035] Specifically, the square electrode assembly in this embodiment includes a plurality of alternately arranged positive and negative electrode plates and an insulating member disposed between the positive and negative electrode plates.

[0036] Specifically, the positive electrode sheet includes a positive current collector and a positive active material disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the opposite surfaces of the positive current collector. As an example, the positive current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be silver-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can include a polymeric material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for battery cells may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0037] Specifically, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the opposite surfaces of the negative electrode current collector. As an example, the negative electrode current collector may be a metal foil, foamed metal, or a composite current collector. For example, as a metal foil, silver-surfaced aluminum or stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc., may be used. The composite current collector may include a polymer material base layer and a metal layer. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0038] Specifically, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. As an example, the main material of the separator membrane can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0039] Furthermore, the separator is a solid electrolyte. The solid electrolyte is placed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0040] Therefore, the powder particles in this embodiment can be, but are not limited to, positive and negative electrode active material particles and current collector debris.

[0041] Specifically, in this embodiment, the sealing tape 4 can be adhered and fixed to the insulating film 3 by its own adhesive properties, or it can be additionally adhered and fixed to the insulating film 3 by means of an adhesive with insulating properties. For example, the adhesive with insulating properties can be a polyvinylidene fluoride (PVDF) adhesive, an acrylic insulating adhesive, or a silicone insulating adhesive.

[0042] According to one embodiment of the present invention, such as Figure 2 As shown, there is a pair of sealing strips 4, located on opposite sides of the electrode assembly in the Y direction. It can be understood that by setting a pair of sealing strips 4 on opposite sides of the electrode assembly in the Y direction, this embodiment of the invention can precisely seal the gaps created by the insulating film 3 wrapping the corresponding narrow side 202 and bottom surface 1, and more specifically block the migration path of square electrode powder particles to the packaging shell in this area, avoiding the formation of local conductive paths that could cause internal micro-short circuits. Simultaneously, it effectively blocks external impurities from intruding through the gaps between the narrow side 202 and the bottom surface 1, further reducing safety risks such as cell bulging and leakage. It also enhances the adhesion stability of the insulating film 3 at the connection between the narrow side 202 and the bottom surface 1, reducing the possibility of the insulating film 3 peeling or falling off at this critical corner during cyclic use or assembly and transportation, ensuring reliable isolation of the square electrode assembly from the packaging shell by the insulating film 3, and guaranteeing the stability of the cell's insulation performance and safety in use.

[0043] According to one embodiment of the present invention, such as Figure 2 and Figure 3As shown, the sealing strip 4 includes a pair of sub-sealing strips. In the Y direction, the pair of sub-sealing strips located on the same side are spaced apart or continuously arranged in the X direction. It can be understood that when continuously arranged, a seamless sealing structure can be formed on the insulating film 3, effectively blocking the penetration path of powder particles and significantly improving sealing reliability. This is suitable for precision equipment or harsh working conditions with extremely high sealing performance requirements. Choosing to spaced out the sealing strips can reduce the amount of material used in the sealing strip 4 while ensuring the basic sealing effect, thereby reducing production costs.

[0044] According to one embodiment of the present invention, such as Figure 2 and Figure 3 As shown, along the X direction, the edges of a pair of sub-sealing strips extend away from each other onto the adjacent large side surface 201, or, along the X direction, the edges of a pair of sub-sealing strips away from each other coincide with the edges of their adjacent narrow side surface 202 and bottom surface 1. It can be understood that the overlap of the edges of the pair of sub-sealing strips away from each other with the edges of their adjacent narrow side surface 202 and bottom surface 1 effectively covers gaps at the edges, reducing the possibility of leakage. Extending the edges of the pair of sub-sealing strips away from each other onto the adjacent large side surface 201 increases the contact area between the sub-sealing strips and the insulating film 3, improves the connection stability between them, and reduces the possibility of the sub-sealing strips detaching from the insulating film 3.

[0045] According to one embodiment of the present invention, such as Figure 3 As shown, in the Y direction, the total width of a pair of sub-sealing strips on the same side in the X direction is 'a', and the value of 'a' is in the range of: 1 / 2 square pole group width ≤ a ≤ 1 / 2 square pole group width + 50 mm, where the width of the square pole group is the dimension of the square pole group in the X direction. Along the X direction, the total width of the two sub-sealing strips on the same side, 'a', is in the range of: 1 / 2 square pole group width ≤ a ≤ 1 / 2 square pole group width + 50 mm. It can be understood that this embodiment of the invention controls the total width 'a' of the two sub-sealing strips on the same side within the range of 1 / 2 square pole group width ≤ a ≤ 1 / 2 square pole group width + 50 mm. This ensures that the sealing strip 4 has sufficient coverage area to seal the gaps of the insulating film 3 on the narrow side 202 and the bottom surface 1, while avoiding material waste due to excessive width of the sealing strip 4. It also prevents the sealing strip 4 from excessively encroaching on the internal space of the battery cell, affecting the compact arrangement of the square pole group and the overall energy density of the battery cell.

[0046] According to one embodiment of the present invention, such as Figure 2 and Figure 4As shown, along the Z direction, the length of the sealing strip 4 on the narrow side 202 is b, and the value of b is in the range of 35mm ≤ b ≤ 50mm; and / or, along the Y direction, the length of the sealing strip 4 on the bottom surface 1 is c, and the value of c is in the range of 35mm ≤ c ≤ 50mm. It can be understood that this embodiment of the invention controls the length b of the sealing strip 4 on the narrow side 202 to between 35mm ≤ b ≤ 50mm, and controls the length c of the sealing strip 4 on the bottom surface 1 to between 35mm ≤ c ≤ 50mm. This ensures that the sealing strip 4 has sufficient coverage area to seal the gaps of the insulating film 3 on the narrow side 202 and the bottom surface 1, while avoiding material waste caused by excessive length of the sealing strip 4. It also prevents the sealing strip 4 from excessively encroaching on the internal space of the battery cell, affecting the compact arrangement of the square electrode group and the overall energy density of the battery cell.

[0047] It is understood that the value of b can be, but is not limited to, 35mm, 38mm, 40mm, 43mm, 45mm, 48mm, 49mm, 50mm or any value between two of these; similarly, the value of c can be, but is not limited to, 35mm, 38mm, 40mm, 43mm, 45mm, 48mm, 49mm, 50mm or any value between two of these. According to one embodiment of the present invention, such as Figure 4 As shown, the thickness of the sealing strip 4 is d, and the value of d ranges from 30μm to 50μm. In this embodiment of the invention, the thickness d of the sealing strip 4 is controlled within the range of 30μm to 50μm. This ensures that the sealing strip 4 has sufficient structural strength and integrity, allowing it to tightly adhere to the bottom surface 1, narrow side surface 202, and corner areas of the electrode assembly, forming a continuous and uniform protective layer. Furthermore, it prevents the sealing strip 4 from excessively encroaching on the limited internal space of the battery, ensuring that the square electrode assembly can be compactly arranged to maintain a high energy density. Simultaneously, it reduces production costs while ensuring the protective effect.

[0048] It is understood that the value of d can be, but is not limited to, 30μm, 35μm, 38μm, 40μm, 43μm, 45μm, 48μm, 49μm, 50μm or any value between the two.

[0049] According to one embodiment of this utility model, the sealing strip 4 is an insulating tape or an insulating coating. Specifically, using insulating tape as the sealing strip 4 allows for quick and easy adhesion and fixation without the need for additional glue mixing or curing, significantly simplifying the assembly process and improving production efficiency. Using an insulating coating as the sealing strip 4, after curing, forms a "thin-film protective layer" that is tightly bonded to the insulating film 3, with no obvious seams, effectively blocking the movement path of the square electrode powder particles. Furthermore, the thickness of the insulating coating can be flexibly controlled according to requirements, without occupying excessive internal space. In addition, compared to insulating tape, the insulating coating has better compatibility with the insulating film 3, eliminating the risk of peeling due to material differences.

[0050] According to one embodiment of this utility model, the sealing strip 4 is an insulating coating, and the material of the insulating coating is a dry-curing thermoplastic material. Specifically, the thermoplastic material itself has both good electrical insulation and a certain degree of flexibility. It can reliably block unnecessary current conduction between the square electrode group and the packaging shell, preventing short circuits. It can also adapt to the slight volume expansion and contraction of the square electrode group during the charging and discharging process of the battery cell, avoiding the cracking and peeling phenomena that are prone to occur in rigid coatings, and ensuring long-term insulation and sealing effects. Secondly, the dry-curing method is simple and efficient, without the need for complex high-temperature sintering or long-term cross-linking reactions, making it more suitable for the pace requirements of large-scale battery cell production.

[0051] It should be noted that the insulating coating in this embodiment can be applied to the corresponding position of the square battery cell by pad printing, where the dried thermoplastic material is transferred and coated. Specifically, the square battery cell is fixed; then, a silicone printhead is used to pick up and print the dried thermoplastic material; finally, a drying process is performed to fully cure the dried thermoplastic material and fix it to the corresponding position of the square battery cell. Specifically, the drying temperature in the drying process is ≤130℃.

[0052] Furthermore, the dried thermoplastic material can be, but is not limited to, polypropylene, polyimide, polyethylene, and polyvinyl chloride.

[0053] According to an embodiment of the present invention, another aspect provides a battery pack, comprising: a housing and a plurality of the aforementioned square battery cells. Specifically, the plurality of the aforementioned square battery cells are arranged side by side within the housing.

[0054] It is understood that the battery pack of this utility model embodiment includes the square battery cell as described above, and has all the beneficial technical effects of the square battery cell, which will not be repeated here.

[0055] Although embodiments of the present 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 present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A square battery cell, characterized in that, include: Encapsulation housing; An electrode assembly is assembled within the encapsulation housing. The electrode assembly includes a square electrode assembly and an insulating film wrapped around the square electrode assembly. The electrode assembly has a bottom surface and side surfaces surrounding the bottom surface. The side surfaces include a pair of large side surfaces arranged opposite each other along the X direction and a pair of narrow side surfaces arranged opposite each other along the Y direction. A sealing tape is applied to the bottom and narrow sides of the electrode assembly to seal any gaps created when the insulating film is bent.

2. The square battery cell according to claim 1, characterized in that, The number of sealing strips is one pair, and the pair of sealing strips are located on opposite sides of the pole assembly in the Y direction.

3. The square battery cell according to claim 2, characterized in that, The sealing strip includes a pair of sub-sealing strips, which are located on the same side in the Y direction and are spaced apart or continuously arranged in the X direction.

4. The square battery cell according to claim 3, characterized in that, Along the X direction, the edges of the pair of sub-sealing strips extend away from each other onto the adjacent large side surface, or, along the X direction, the edges of the pair of sub-sealing strips away from each other coincide with the edges of the adjacent narrow side surface and the bottom surface.

5. The square battery cell according to claim 4, characterized in that, In the Y direction, the sum of the widths of the pair of sub-sealing strips on the same side in the X direction is a, and the value of a is in the range of: 1 / 2 the width of the square pole group ≤ a ≤ 1 / 2 the width of the square pole group + 50 mm, wherein the width of the square pole group is the dimension of the square pole group in the X direction.

6. The square battery cell according to any one of claims 1 to 5, characterized in that, Along the Z direction, the length of the sealing strip on the narrow side is b, where b ranges from 35mm to 50mm; and / or, along the Y direction, the length of the sealing strip on the bottom surface is c, where c ranges from 35mm to 50mm.

7. The square battery cell according to any one of claims 1 to 5, characterized in that, The thickness of the sealing strip is d, and the value of d ranges from 30μm to 50μm.

8. The square battery cell according to any one of claims 1 to 5, characterized in that, The sealing tape is an insulating tape or an insulating coating.

9. The square battery cell according to claim 8, characterized in that, The sealing strip is an insulating coating, and the insulating coating is made of a dry-type thermoplastic material.

10. A battery pack, characterized in that, include: Box; The square battery cells according to any one of claims 1 to 9 are arranged side by side in the housing.

Images