Battery module, battery pack, and electric device

Abstract

The application relates to the field of batteries, and particularly provides a battery module, a battery pack and a power utilization device. The battery module comprises a battery pack and at least one end plate. The battery pack comprises at least two soft package battery monomers arranged along a first direction. The battery pack has two opposite first end faces. The first shell and the second shell of the outer shell of the soft package battery monomer are adhesively connected to form a sealing edge. The end plate is arranged on the first end face of the battery pack. The sealing edge is arranged opposite to the end plate. The end plate is provided with a protruding part protruding away from the soft package battery monomer. The bottom wall of the protruding part is provided with a through hole penetrating through the bottom wall. The orthographic projection of the through hole on the first end face at least partially overlaps the orthographic projection of the sealing edge of at least one soft package battery monomer on the first end face. The bottom wall of the protruding part and the sealing edge of the soft package battery monomer are arranged in a second direction to form an air storage cavity between the bottom wall of the protruding part and the sealing edge of the soft package battery monomer. The second direction is perpendicular to the first end face.

Description

Technical Field

[0001] This application relates to the field of batteries, specifically to a battery module, a battery pack, and an electrical device. Background Technology

[0002] Soft-pack batteries are a type of battery product with an aluminum-plastic composite film as the encapsulation shell. Their internal core structure is similar to that of cylindrical and square hard-shell batteries, mainly including key components such as positive electrode, negative electrode, separator and electrolyte.

[0003] Due to the flexibility and narrow sealing edge of the aluminum-plastic film packaging, pouch batteries cannot be equipped with directional explosion-proof valve structures. When the battery experiences increased internal pressure due to extreme conditions such as overcharging or high temperatures, even if the pouch battery ruptures, the strong constraint of the outer frame will prevent proper venting, leading to a continuous accumulation of internal pressure. This accumulation of internal pressure not only exacerbates heat spread between batteries but also, due to the soft texture and high risk of deformation of the pouch battery casing, can further cause the casing to crack, creating a connection between the battery's interior and exterior. This can easily lead to severe thermal runaway safety accidents such as battery module fires or explosions. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide a battery module, battery pack and electrical device to solve the technical problem of poor pressure relief effect of existing soft-pack battery modules.

[0005] The first aspect of this application provides a battery module, comprising:

[0006] A battery pack, the battery pack comprising at least two pouch battery cells arranged along a first direction, the battery pack having two opposing first end faces, the outer shell of the pouch battery cell comprising a first shell and a second shell disposed opposite to each other, the first shell and the second shell being bonded together to form a sealing edge;

[0007] At least one end plate is disposed on the first end face of the battery pack. The sealing edge is disposed opposite to the end plate. The end plate is provided with a protrusion that protrudes away from the soft-pack battery cell. A through hole is provided on the bottom wall of the protrusion. The orthographic projection of the through hole on the first end face at least partially coincides with the orthographic projection of the sealing edge of at least one soft-pack battery cell on the first end face.

[0008] The bottom wall of the protrusion and the sealing edge of the soft-pack battery cell are spaced apart in a second direction to form an air storage cavity between the bottom wall of the protrusion and the sealing edge of the soft-pack battery cell. The second direction is perpendicular to the first end face.

[0009] Another aspect of this application provides a battery pack including at least one of the battery modules.

[0010] Another aspect of this application provides an electrical device including at least one of the battery modules or the battery pack.

[0011] During the operation of the battery module in this application embodiment, the internal pressure of a certain soft-pack battery cell gradually increases due to extreme conditions such as overcharging and high temperature. When the pressure reaches the withstand threshold of the sealing edge, the sealing edge ruptures, and the high-temperature gas generated inside quickly enters the gas storage chamber. The gas storage chamber buffers the high-temperature gas and guides the gas flow to the through hole. Finally, the gas is discharged to the outside of the battery module through the through hole, completing the pressure relief process.

[0012] In the battery module of this application embodiment, a protrusion and a through hole are provided on the end plate, and the sealing edge is arranged opposite to the through hole on the end plate. The protrusion and the sealing edge form a gas storage cavity, which realizes the directional decompression of gas after the soft pack battery cell ruptures. This can effectively solve the problem of poor gas exhaust in existing soft pack battery modules, thereby avoiding severe thermal runaway and heat propagation caused by the accumulation of internal pressure in the battery module, and significantly improving the safety of the battery module. Attached Figure Description

[0013] It should be understood that the following figures only illustrate certain embodiments of this application and should not be construed as limiting the scope.

[0014] It should be understood that the same or similar reference numerals are used in the accompanying drawings to denote the same or similar elements.

[0015] It should be understood that the accompanying drawings are only schematic, and the dimensions and scales of the elements in the drawings are not necessarily precise.

[0016] Figure 1 This is a three-dimensional schematic diagram of a single soft-pack battery cell according to an embodiment of this application.

[0017] Figure 2 This is a partial perspective view of a single soft-pack battery cell according to an embodiment of this application.

[0018] Figure 3 This is a partial perspective view of a single soft-pack battery cell according to an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the end face of a single soft-pack battery cell according to an embodiment of this application.

[0020] Figure 5 This is a partial cross-sectional schematic diagram of a single soft-pack battery cell according to an embodiment of this application.

[0021] Figure 6 This is a schematic diagram of the internal end face of a single soft-pack battery cell according to an embodiment of this application.

[0022] Figure 7This is a partial cross-sectional schematic diagram of a single soft-pack battery cell according to an embodiment of this application.

[0023] Figure 8 This is a partial perspective view of another soft-pack battery cell according to an embodiment of this application.

[0024] Figure 9 This is a schematic diagram of the end face of another soft-pack battery cell according to an embodiment of this application.

[0025] Figure 10 This is a partial perspective view of another soft-pack battery cell according to an embodiment of this application.

[0026] Figure 11 This is a schematic diagram of the end face of another soft-pack battery cell according to an embodiment of this application.

[0027] Figure 12 This is a partial cross-sectional schematic diagram of another soft-pack battery cell according to an embodiment of this application.

[0028] Attached image labels:

[0029] 10. Battery pack; 11. Soft-pack battery cell; 111. First housing; 112. Second housing; 113. Sealing edge; 114. Electrode sheet; 1141. First electrode sheet; 1142. Second electrode sheet; 15. First surface; 12. First end face; 20. End plate; 21. Protrusion; 22. Through hole; 23. Groove; 30. Separator plate; 31. Weak part.

[0030] X - First direction; Y - Second direction; Z - Third direction. Detailed Implementation

[0031] Numerous specific details are set forth below to provide an understanding of the structure, function, and use of the embodiments described and illustrated in the specification and figures. It is to be understood that the embodiments described and illustrated herein are non-limiting examples, and thus it will be appreciated that the particular structural and functional details disclosed herein are representative and exemplary. Variations and changes may be made to these embodiments without departing from the scope of the claims.

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] like Figures 1 to 12As shown, this application embodiment provides a battery module, which includes a battery pack 10 and at least one end plate 20. The battery pack 10 includes at least two pouch battery cells 11 arranged along a first direction. The battery pack 10 has two opposing first end faces 12. The outer casing of the pouch battery cell 11 includes a first housing 111 and a second housing 112 disposed opposite to each other. The first housing 111 and the second housing 112 are bonded together to form a sealing edge 113.

[0034] It is understandable that the soft-pack battery cell 11 mostly uses a flexible aluminum-plastic film as the outer shell, and contains core components such as the battery cell and electrolyte. The first shell 111 and the second shell 112 of the outer shell can be sealed by adhesive bonding. The first shell 111 and the second shell 112 can be two parts of the same shell, or they can be two relatively independent shells. No restrictions are placed here.

[0035] Specifically, the outer casing of the pouch cell 11 may include an outer insulating layer, an intermediate metal layer, and an inner sealing layer. The outer insulating layer can be made of one or more materials such as polycaprolactam (nylon 6), PET (polyethylene terephthalate), or polybutylene succinate, primarily responsible for maintaining the shape stability of the pouch cell 11's casing and ensuring that the casing does not deform during manufacturing. The intermediate metal layer can be made of one or more metals or alloys such as aluminum, aluminum alloy, copper, or nickel. The inner sealing layer can be made of one or more materials such as polypropylene film (PP) and cast polypropylene film (CPP). The outer insulating layer itself is not waterproof and cannot meet waterproofing requirements; the intermediate metal layer's main function is waterproofing. After reacting with oxygen in the air, the intermediate metal layer forms a dense oxide film, preventing water vapor penetration and protecting the inside of the cell. Furthermore, the intermediate metal layer provides the necessary plasticity during the casing molding process to meet the requirements of the perforation process.

[0036] like Figure 2 As shown, after the first housing 111 and the second housing 112 are bonded together, a sealing edge 113 is formed at their edges. The sealing edge 113 can ensure the sealing of the soft-pack battery cell 11 and prevent electrolyte leakage. At the same time, it can rupture and release gas when the soft-pack battery cell 11 is overloaded with gas.

[0037] Specifically, there are several ways to bond the first housing 111 and the second housing 112 together. They can be bonded together by heat-melting the inner sealing layer of the first housing 111 and the inner sealing layer of the second housing 112, or they can be bonded together by adhesive.

[0038] It is understood that the pouch cell 11 contains a battery cell; the battery cell is the component in the battery where electrochemical reactions occur, and is the smallest unit capable of electrochemical reactions such as charging / discharging. It typically includes a positive electrode, a negative electrode, and a separator, with the separator located between adjacent positive and negative electrodes. Specifically, the battery cell generally operates by the intercalation and deintercalation of corresponding ions between the positive and negative electrodes; the structure of the battery cell can be either wound or stacked; no limitation is made here. For example, in a cylindrical battery cell, the three-layer thin-film structure is wound into a cylindrical electrode assembly, while in a cuboid battery cell, the thin-film structure is wound or stacked into an electrode assembly with a roughly cuboid shape.

[0039] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (e.g., lithium ions) are released from the crystal lattice of the positive electrode active material (oxidation reaction), migrate through the electrolyte, and intercalate into the negative electrode. During discharging, metal ions (e.g., lithium ions in a lithium battery) are released from the negative electrode and intercalated into the crystal lattice of the positive electrode active material (reduction reaction), thus realizing the storage and release of lithium ions.

[0040] A positive electrode generally includes a positive current collector and a positive active material layer. The positive active material layer is coated on at least one surface of the positive current collector and includes: a positive active material, a conductive agent, and a binder. The positive active material includes, but is not limited to, at least one of the following: lithium phosphates, lithium transition metal oxides and their respective modified compounds, or other conventional materials that can be used as positive active materials for batteries. These positive active materials can be used alone or in combination. The lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Lithium transition metal oxides include, but are not limited to, at least one of lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, lithium nickel cobalt manganese oxides, and their modified compounds.

[0041] The positive electrode current collector includes a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface. The positive electrode current collector can also include a composite current collector, which may include a polymer material substrate and a metal layer. Composite current collectors are formed by forming a metal material (aluminum, aluminum alloys, copper, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys, etc.) on a polymer material substrate (such as a substrate of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0042] The positive electrode conductive agent includes, but is not limited to, one or more combinations of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon nanotubes, graphene and carbon nanofibers.

[0043] The positive electrode binder includes, but is not limited to, one or more combinations of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, etc.

[0044] The negative electrode includes a negative current collector and a negative active layer disposed on at least one surface of the negative current collector. The negative current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium with a silver-plated surface. The composite current collector may include a polymer base material and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, copper, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene, etc.).

[0045] The negative electrode active layer includes the negative electrode active material, conductive components, and binders. The negative electrode active material can be carbon-based materials such as graphite, porous carbon, hard carbon, soft carbon, and mesophase carbon microspheres, or silicon-based materials such as elemental silicon, silicon oxides, silicon-carbon composites, and silicon-ammonia composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0046] Understandably, the battery cell also includes a current output terminal, which is located on one side of the positive / negative current collector of the battery cell and is separately or integrally formed with the current collector. It is electrically connected to the current collector to conduct the current on the corresponding current collector. When the current output terminal and the current collector are separately set, the current output terminal and the current collector can be connected by welding. The current output terminal is usually made of a metal material with good conductivity (such as copper, aluminum, copper or nickel).

[0047] Specifically, in one embodiment of this application, the current output terminal is located on the end face of the pouch battery cell 11. It is understood that the pouch battery cell 11 also includes an electrode plate 114, one end of which is electrically connected to the current output terminal, and the other end is electrically connected to other external batteries or electrical devices. The electrode plate 114 at least partially passes through the sealing edge 113. The pouch battery cell 111 can discharge to external devices through the cell output terminal (tab) and the electrode plate 114, and an external power source can charge the pouch battery cell 11 through the electrode plate and the cell output terminal (tab). The electrode plate 114 can be at least one or more materials or alloys selected from aluminum, aluminum alloy, copper, copper-aluminum alloy, steel, stainless steel, and nickel.

[0048] In one embodiment of this application, an insulating seal is further provided between the current output terminal and the first housing 111 or the second housing 112 of the soft-pack battery cell 11. The insulating seal is provided between the housing and the current output terminal to insulate the current output terminal and the housing. The insulating seal can be made of insulating materials such as polypropylene (CPP), polyethylene (PE), polyethylene terephthalate (PET), polybutylene succinate (PBS), and polyimide (PI).

[0049] Studies have found that, compared to prismatic and cylindrical batteries, pouch cell 11 is mostly sealed using adhesive bonding. Compared to welding and riveting, adhesive bonding of pouch cell 11 carries a higher risk of structural failure. Specifically, to suppress deformation of the battery module composed of pouch cell 11, end plates are installed on the outside of the battery module. These end plates are secured to the outer perimeter of the battery module using cable ties or other welded fixing plates, resulting in significant constraint of the pouch cells by the outer frame. If the sealing edge 113 of the pouch cell 11 bursts, insufficient venting leads to high internal pressure within the battery module, which can easily cause heat propagation from multiple pouch cell 11s, resulting in a fire and explosion of the battery module.

[0050] Understandably, since the current output terminal of the battery cell extends outward from the sealing edge 113, and the electrode plate 114 at least partially passes through the sealing edge 113, heat generation at the sealing edge 113 is relatively concentrated, and the electrode plate 114 is located at the sealing edge 113. Therefore, when the pouch battery cell 11 experiences thermal runaway, the sealing edge 113 is prone to cracking. The current output terminal can have a multi-layer structure to facilitate venting when the pouch battery cell 11 experiences thermal runaway, effectively improving the venting rate of the pouch battery cell 11.

[0051] like Figure 3As shown, end plate 20 is disposed on the first end face 12 of battery pack 10, and sealing edge 113 is disposed opposite to end plate 20; end plate 20 can protect the end of battery pack 10 to prevent foreign objects or moisture from contacting the electrode plates 114 of soft-pack battery cell 11, avoiding short circuit; end plate 20 also limits and fixes battery pack 10, improves the mechanical strength of battery pack 10, and prevents the end of battery pack 10 from deforming. End plate 20 can also serve as the positive and negative electrode leads of battery module. That is, positive and negative electrode leads can be provided on end plate 20 as the positive and negative electrode output terminals of battery module, and the positive and negative electrode leads are electrically connected to the electrode plates 114 of some soft-pack battery cells 11 in battery pack 10. It can be understood that the material of end plate 20 can be aluminum alloy, iron, stainless steel and other metals; the battery module of this application embodiment can be provided with only one end plate 20 on one side of battery pack 10, or end plates 20 can be provided on both sides of battery pack 10.

[0052] like Figure 3 and Figure 4 As shown, the end plate 20 is provided with a protrusion 21 that protrudes in the direction away from the battery pack 10, such as Figure 5 As shown, the bottom wall of the protrusion 21 and the sealing edge 113 of the soft-pack battery cell 11 are spaced apart in a second direction to form a gas storage cavity between the bottom wall of the protrusion 21 and the sealing edge 113 of the soft-pack battery cell 11. The second direction is perpendicular to the first end face 12. Specifically, the protrusion 21 is formed by a bottom wall and a side wall. The bottom wall is a planar structure, and the side wall is a surrounding wall located around the bottom wall, and the side wall is connected to the body part of the end plate 20. Since the bottom wall of the protrusion 21 and the sealing edge 113 of the soft-pack battery cell 11 are spaced apart in a second direction, the space between them can be used to form a gas storage cavity between the bottom wall of the protrusion 21 and the sealing edge 113 of the soft-pack battery cell 11. The gas storage cavity can be used to temporarily store the gas discharged after the sealing edge 113 of the soft-pack battery cell 11 ruptures, relieve pressure shock, and guide the gas flow to the through hole 22.

[0053] It is understood that in the battery module of this application embodiment, the first direction can be perpendicular to the second direction, so that the arrangement direction of the soft-pack battery cells 11 is parallel to the first end face 12 of the battery pack 10.

[0054] like Figure 6 As shown, a through hole 22 is provided on the bottom wall of the protrusion 21. The orthographic projection of the through hole 22 on the first end face 12 at least partially coincides with the orthographic projection of the sealing edge 113 of at least one soft-pack battery cell 11 on the first end face 12.

[0055] The through hole 22 can serve as a channel for gas to be discharged from the battery module. Since the orthographic projection of the through hole 22 on the first end face 12 at least partially coincides with the orthographic projection of the sealing edge 113 of at least one soft-pack battery cell 11 on the first end face 12, the gas discharged after the sealing edge 113 of the battery cell breaks can be discharged from the corresponding through hole 22 as soon as possible after entering the gas storage chamber, so as to ensure smooth exhaust.

[0056] It is understood that the orthographic projection of the through hole 22 on the first end face 12 can at least partially coincide with the orthographic projection of the sealing edge 113 of all the pouch battery cells 11 on the first end face 12, or it can at least partially coincide with the orthographic projection of the sealing edge 113 of some of the pouch battery cells 11 on the first end face 12; the shape of the through hole can be Figure 3 and Figure 4 The square shape can also be a circle, an oval, a racetrack, or other shapes; there are no restrictions on its shape.

[0057] Specifically, such as Figure 5 As shown, in one embodiment of this application, the thickness of the end plate 20 is d mm, where d mm satisfies 0.5 mm ≤ d mm ≤ 3 mm. When the thickness d mm of the end plate 20 is greater than 3 mm, the forming of the through hole 22 is more difficult, and the gas ejected when the soft-pack battery cell 11 experiences severe thermal runaway is unlikely to break through the end plate 20. When the thickness d mm of the end plate 20 is less than 0.5 mm, the end plate 20 has lower strength and is prone to breakage. Therefore, when the thickness of the end plate 20 is d mm, where d mm satisfies 0.5 mm ≤ d mm ≤ 3 mm, the forming difficulty of the through hole 22 can be effectively reduced, ensuring that the gas ejected when the soft-pack battery cell 11 experiences severe thermal runaway can break through the end plate 20, and also effectively ensuring the structural strength of the end plate 20 and preventing breakage.

[0058] like Figure 1 As shown, the battery module in this embodiment may include at least one of a side plate, a top plate, and a bottom plate. The side plate is disposed at both ends in a first direction of the battery module, and the top plate and bottom plate are respectively disposed at both ends in a third direction. The end plate is connected to at least one of the side plate, bottom plate, and top plate by riveting, welding, bonding, or by binding and fixing with cable ties. The side plate, top plate, and bottom plate are all used to constrain the battery pack 10.

[0059] As mentioned above, in the battery module of this application embodiment, the sealing edge 113 generates severe heat, and is prone to cracking when the soft-pack battery cell 11 experiences thermal runaway. During the operation of the battery module of this application embodiment, the internal pressure of a certain soft-pack battery cell 11 gradually increases due to extreme conditions such as overcharging and high temperature. When the pressure reaches the withstand threshold of the sealing edge 113, the sealing edge 113 ruptures, and the high-temperature gas generated inside quickly enters the gas storage chamber. The gas storage chamber buffers the high-temperature gas and guides the gas flow to the through hole 22. Finally, the gas is discharged outside the battery module through the through hole 22, completing the pressure relief process.

[0060] In this embodiment of the battery module, a protrusion 21 and a through hole 22 are provided on the end plate 20, and the sealing edge 113 is arranged opposite to the through hole 22 on the end plate 20. The protrusion 21 and the sealing edge 113 form a gas storage cavity, which realizes the directional decompression of gas after the soft-pack battery cell 11 ruptures. This can effectively improve and solve the problem of poor gas exhaust in existing soft-pack battery modules, thereby avoiding severe thermal runaway and heat propagation caused by the accumulation of internal pressure in the battery module, and significantly improving the safety of the battery module.

[0061] Specifically, in one embodiment of this application, the outer shell of the soft-pack battery cell 11 includes an inner sealing layer, an intermediate metal layer, and an outer insulating layer; the inner sealing layer of the first shell 111 and the inner sealing layer of the second shell 112 are bonded together.

[0062] The inner sealing layer, serving as the outer shell of the pouch battery cell 11 close to the internal cell, is typically made of thermoplastic material, possessing excellent thermal bonding properties. This allows for a sealed connection between the first shell 111 and the second shell 112 via thermal bonding. The intermediate metal layer is usually made of aluminum foil, which acts as a barrier against oxygen, moisture, and electrolyte, ensuring a stable internal environment for the battery. The outer insulating layer is typically made of plastic film, providing insulation and protection to prevent short circuits between the battery casing and external components. The inner sealing layers of the first shell 111 and the second shell 112 are fused together via thermal bonding, forming a sealing edge 113 to ensure the battery's airtightness. The electrode sheet 114 can extend outwards from the sealing edge 113, thus achieving electrical connection between the pouch battery cell 11 and the external environment.

[0063] The three-layer shell structure of the soft-pack battery cell 11 in this application embodiment can effectively ensure sealing and stability. When gas is generated inside the battery, the sealing edge 113 can withstand a certain pressure until the pressure reaches the threshold and then ruptures to release gas.

[0064] like Figure 5As shown, in one embodiment of this application, the sealing edge 113 extends in the second direction with a width of L(1) mm, and the protrusion of the protrusion 21 in the second direction is H mm, where L(1)×H satisfies 16≤L(1)×H≤300.

[0065] Specifically, the preparation method of the soft-pack battery cell 11 in this application embodiment includes:

[0066] (1) Preparation of positive electrode sheet: The positive electrode active material, conductive agent acetylene black, and binder PVDF are mixed, and solvent NMP is added. The mixture is stirred under vacuum until the system is homogeneous to obtain a positive electrode slurry. The positive electrode slurry is uniformly coated on both surfaces of the positive electrode current collector aluminum foil, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the positive electrode sheet is obtained. The mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0067] (2) Preparation of negative electrode sheet: The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as solvent. The mixture is stirred under vacuum until the system is homogeneous to obtain a negative electrode slurry. The negative electrode slurry is uniformly coated on both surfaces of the negative electrode current collector copper foil, dried at room temperature, and then transferred to an oven for further drying. After cold pressing and slitting, the negative electrode sheet is obtained. The ratio of negative electrode active material: conductive agent: thickener: binder satisfies (90~96): (4~2): (2~1): (4~1).

[0068] (3) Preparation of electrolyte: Ethyl carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0069] (4) Preparation of diaphragm: polyethylene film is selected as the diaphragm.

[0070] (5) Preparation of lithium-ion battery: The above positive electrode, separator and negative electrode are stacked in sequence to form a cell; the cell is placed in an aluminum-plastic shell, the inner layer of the aluminum-plastic shell is cast polypropylene (CPP), the middle layer is metallic aluminum, and the outer layer is polycaprolactam (nylon 6); the edges are sealed with a heat sealer and a liquid injection port is reserved. The battery is dried and then injected with electrolyte. After standing, formation, volume adjustment and final sealing, a soft pack battery is obtained.

[0071] The positive electrode active material can be selected from one or more lithium-containing positive electrode active materials, including lithium iron phosphate, ternary materials containing nickel, cobalt, and manganese, and lithium manganese iron phosphate; the negative electrode active material can be selected from one or more negative electrode active main materials, such as artificial graphite, natural graphite, silicon carbide, silicon oxide, and lithium titanate.

[0072] After obtaining the aforementioned soft-pack battery cell 11, the battery module can be prepared. Specifically, the preparation process of the battery module is as follows: nine soft-pack battery cells 11 prepared by the above preparation method are stacked along the first direction and connected in series. An end plate 20 is provided on the first end face 12 of the battery pack 10. A protrusion 21 facing away from the battery pack 10 is provided on the end plate 20, and a through hole 22 is provided on the protrusion 21 so that the projection of the sealing edge 113 on the end plate 20 overlaps with the through hole 22. The protrusion 21 and the sealing edge 113 of the soft-pack battery cell 11 are spaced apart in the second direction, and the first direction is perpendicular to the second direction.

[0073] Multiple battery modules were prepared according to the above-described battery pack preparation method. One battery module was prepared for each embodiment and comparative example. In the battery modules of each embodiment and comparative example, the extension width of the sealing edge 113 in the second direction is L(1) mm, and the protrusion width of the protrusion 21 in the second direction is H mm, as shown in Table 1 below. Apart from this, the rest of the structures are the same.

[0074] The thermal runaway test method is as follows: Each pouch cell 11 in the battery module is charged to the upper limit voltage at a rate of 0.33C. A high-temperature resistant steel needle with a diameter of 3 mm is used to penetrate the middle pouch cell 11 from a third direction at a speed of 25±5 mm per second (since the battery pack 10 has 9 pouch cells 11, the 5th pouch cell 11 is the middle pouch cell 11), inducing thermal runaway in the middle pouch cell 11. Timing starts from the moment the middle pouch cell 11 thermally runs away, and the shortest time for thermal runaway of other pouch cells 11 in the battery pack 10 is obtained. If the shortest time for thermal runaway of other pouch cells 11 is greater than or equal to 6 minutes, the result of the thermal runaway test is good; if the shortest time for thermal runaway of other pouch cells 11 is greater than or equal to 5 minutes and less than 6 minutes, the result of the thermal runaway test is qualified; if the shortest time for thermal runaway of other pouch cells 11 is less than 5 minutes, the result of the thermal runaway test is unqualified.

[0075] Specifically, when the positive electrode active material of the soft-pack battery cell 11 is nickel-cobalt-manganese ternary lithium, the aforementioned upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the soft-pack battery cell 11 is lithium iron phosphate, the aforementioned upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0076] Specifically, in this test, the positive electrode active material of the soft-pack battery cell 11 is lithium iron phosphate, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0077] The structural strength test method is as follows: Each soft-pack battery cell 11 in the battery module is charged to the upper limit voltage at a rate of 0.33C. The battery module is placed in a vibration table and subjected to random vibration in the Z / Y / X directions and sinusoidal fixed-frequency vibration in accordance with the national standard GB38031-2020.8.2. After continuous random vibration for 12 hours and sinusoidal fixed-frequency vibration for 2 hours in each direction, the battery pack is removed and the deformation of the end plate is measured. If the deformation is less than 1mm, it is considered good; if the deformation is between 1 and 2mm, it is considered qualified; and if the deformation is greater than 2mm, it is considered unqualified.

[0078] Specifically, when the positive electrode active material of the soft-pack battery cell 11 is nickel-cobalt-manganese ternary lithium, the aforementioned upper limit voltage is 4.25V and the lower limit voltage is 2.5V. When the positive electrode active material of the soft-pack battery cell 11 is lithium iron phosphate, the aforementioned upper limit voltage is 3.6V and the lower limit voltage is 2.5V.

[0079] Specifically, in this test, the positive electrode active material of the soft-pack battery cell 11 is lithium iron phosphate, and the mass ratio of positive electrode active material: conductive agent: binder meets 96:2:2; the negative electrode active material is selected from artificial graphite, and the ratio of negative electrode active material: conductive agent: thickener: binder meets 95:2:1:2.

[0080] Table 1: Results of Thermal Runaway Tests and Structural Strength Tests in Examples and Comparative Examples

[0081]

[0082] It is understandable that the extension width L(1) mm of the sealing edge 113 in the second direction is the thickness of the sealing edge 113 along the gas discharge direction, which can affect the sealing strength of the sealing edge 113 and the gas discharge rate when it breaks. The protrusion height H mm of the protrusion 21 in the second direction is the distance between the bottom wall of the protrusion 21 and the body of the end plate 20, which can affect the volume of the gas storage chamber.

[0083] When the extension width of the sealing edge 113 in the second direction is L(1) mm and the protrusion width of the protrusion 21 in the second direction is H mm, and L(1)×H is less than 16, the gas storage cavity volume is too small, which cannot effectively buffer the high-temperature gas, and the gas discharge rate is insufficient, which can easily lead to poor pressure relief of the battery module. Referring to Table 1, in Comparative Examples 1 and 3, L(1)×H is less than 16, and the thermal runaway test results are all unqualified.

[0084] When L(1)×H is greater than 300, an excessively wide sealing edge 113 will reduce the effective capacity of the soft-pack battery cell 11, and an excessively high protrusion 21 will reduce the structural strength of the end plate 20, making it prone to deformation under vibration conditions, and will also affect the energy density of the battery module in this embodiment. Referring to Table 1, in Comparative Examples 2 and 4, L(1)×H is greater than 300, and the structural strength test results are all unqualified.

[0085] Therefore, when L(1)×H satisfies 16≤L(1)×H≤300, it can effectively ensure that the gas in the battery module of this application embodiment can be smoothly discharged after the soft-pack battery cell 11 is broken, avoiding severe thermal runaway caused by thermal propagation. It can also effectively ensure the structural strength of the end plate 20, thereby ensuring the fixing strength of the end plate 20 to the battery pack 10, preventing the battery from being damaged under vibration conditions, and effectively improving the energy density of the battery module of this application embodiment.

[0086] Referring to Table 1, in Examples 1-13, L(1)×H all satisfy 16≤L(1)×H≤300, the thermal runaway test results are all good or qualified, and the structural strength test results are good or qualified. In specific embodiments, the specific value of L(1)×H can be selected from 16, 20, 25, 32, 40, 64, 100, 160, 200, 300, etc., and is not limited here.

[0087] Specifically, such as Figure 5 As shown, in one embodiment of this application, the extension width L(1) mm of the sealing edge 113 in the second direction satisfies 6mm≤L(1) mm≤35 mm.

[0088] When the extension width L(1) mm of the sealing edge 113 in the second direction is less than 6 mm, the sealing strength of the sealing edge 113 is insufficient. The soft-pack battery cell 11 of this application embodiment is not only prone to electrolyte leakage, but also prone to excessive pressure inside the soft-pack battery cell 11. The sealing edge 113 is prone to instantaneous and complete collapse, resulting in excessive gas impact. Referring to Table 1, the value of L(1) in Example 11 is 5.4 mm, and the corresponding thermal runaway test result is only qualified. When L(1) mm is greater than 35 mm, the sealing edge 113 will occupy a large amount of space, affecting the energy density of the battery module of this application embodiment.

[0089] Therefore, when the extension width L(1) mm of the sealing edge 113 in the second direction satisfies 6mm≤L(1) mm≤35 mm, the sealing strength of the sealing edge 113 can be guaranteed to be sufficient, preventing electrolyte leakage. It can also avoid the complete collapse of the sealing edge 113, which would lead to excessive gas impact inside the battery module. At the same time, it saves the space occupied by the sealing edge 113 and improves the energy density of the battery module in this embodiment. Referring to Table 1, the L(1) mm of embodiments 1-10 and 12 all satisfy 6mm≤L(1) mm≤35 mm, and the thermal runaway test results are all good or qualified.

[0090] In a specific embodiment, the specific value of the extension width L(1) mm of the sealing edge 113 in the second direction can be selected as 6mm, 8mm, 10mm, 12mm, 13mm, 15mm, 18mm, 20mm, 23mm, 26mm, 30mm, 35mm, etc., and is not limited here.

[0091] Specifically, such as Figure 5 As shown, in one embodiment of this application, the protrusion width H mm of the protrusion 21 in the second direction satisfies 2 mm ≤ H mm ≤ 10 mm. When the protrusion width H mm of the protrusion 21 in the second direction is less than 2 mm, the gas storage cavity volume is too small, which cannot effectively buffer the high-temperature gas, and the gas discharge rate is insufficient, which can easily lead to poor pressure relief of the battery module; referring to Table 1, H mm in Embodiment 12 is 1.5 mm, and the corresponding structural strength test result is only qualified.

[0092] When H mm is greater than 10 mm, it can easily lead to a decrease in the structural strength of the end plate 20 and increase the overall volume of the battery module, affecting the adaptability of the installation space.

[0093] Therefore, when the protrusion width H mm of the protrusion 21 in the second direction satisfies 2 mm ≤ H mm ≤ 10 mm, the gas storage cavity volume is moderate, which can adequately buffer high-temperature gas without reducing the structural strength of the end plate 20 due to excessive volume. The end plate 20 has good fixing strength to the battery pack 10, and the battery pack 10 will not shift or be damaged under vibration conditions during vehicle operation. Referring to Table 1, H mm in Examples 1-11 and 13 all satisfy 2 mm ≤ H mm ≤ 10 mm, and the structural strength results are all good or qualified. In specific embodiments, the specific value of the protrusion width H mm of the protrusion 21 in the second direction can be selected as 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.8 mm, 5.8 mm, 6.9 mm, 8.3 mm, 10 mm, etc., and is not limited here.

[0094] like Figure 1As shown, in one embodiment of this application, the third direction is a direction perpendicular to the second direction and the first direction, respectively; specifically, the third direction can be the height direction of the battery module in this embodiment of the application, or it can be other directions, which are not limited here.

[0095] like Figure 1 As shown, in one embodiment of this application, the extension length of the pouch cell 11 in the second direction is greater than the extension length in the first direction and greater than the extension length in the third direction.

[0096] The second direction is the length direction of the pouch cell 11. The internal space of the battery is larger in this direction. Since the electrode plates 114 are mostly located at both ends of the pouch cell 11 in the second direction, gas accumulation is prone to occur at both ends of the battery pack 10 in this embodiment, leading to poor venting. By placing the end plate 20 at at least one end of the battery pack 10 in the second direction, a gas storage cavity can be formed between the end plate 20 and the pouch cell 11. The through hole 22 on the protrusion 21 allows the gas accumulated in the battery module of this embodiment to quickly enter the gas storage cavity and be discharged through the through hole 22.

[0097] like Figure 2 As shown, in one embodiment of this application, the outer casing of the pouch battery cell 11 has a first surface 15, which is arranged parallel to the first end face 12, and the sealing edge 113 is configured to extend outward from the first surface 15 along a second direction.

[0098] That is, the first surface 15 is the surface on the outer shell of the soft-pack battery cell 11 that is parallel to the first end face 12 of the battery pack 10, and is the carrier for setting the sealing edge 113. The sealing edge 113 extends outward from the first surface 15 along the second direction, that is, the direction away from the interior of the soft-pack battery cell 11.

[0099] When gas is generated inside the soft-pack battery cell 11, the gas pressure acts directly on the sealing edge 113 extending outward along the second direction. The force on the sealing edge 113 is relatively concentrated. After the sealing edge 113 ruptures, the gas can be discharged outward along the second direction, shortening the exhaust path, further improving the exhaust efficiency, and reducing the risk of thermal runaway of the battery module in this application embodiment.

[0100] Furthermore, in one embodiment of this application, the outer casing of the pouch battery cell 11 has two opposing first surfaces 15 at both ends in the second direction, and both opposing first surfaces 15 are provided with sealing edges 113. That is, the outer casing of the pouch battery cell 11 has sealing edges 113 at both ends in the second direction, so that both ends of the pouch battery cell 11 in this embodiment of the application can be effectively depressurized, thereby improving the exhaust efficiency.

[0101] Furthermore, such as Figure 1As shown, in one embodiment of this application, the battery module has two end plates 20, which are respectively disposed on two first end faces 12 of the battery pack 10, and the through holes 22 of the two end plates 20 are respectively disposed corresponding to the sealing edges 113 of the opposite soft-pack battery cells 11.

[0102] During the operation of the battery module in this embodiment, when gas is generated inside the soft-pack battery cell 11 and causes the sealing edge 113 at any end to rupture, the gas can enter the corresponding gas storage chamber. Each gas storage chamber can buffer the gas and guide the gas flow to the through hole 22, so that the gas can be discharged from the battery module through the through hole 22. This allows both ends of the battery module in this embodiment to have pressure relief function, greatly improving the pressure relief efficiency, avoiding the gas accumulation problem that may occur when only one side is depressurized, and further reducing the risk of thermal runaway and thermal propagation of the battery module in this embodiment.

[0103] like Figure 7 As shown, in one embodiment of this application, the through hole 22 of the end plate 20 is correspondingly provided with the sealing edge 113 of at least two opposite soft-pack battery cells 11.

[0104] Since the through hole 22 of the end plate 20 is correspondingly provided with the sealing edge 113 of at least two pouch cell 11, the through hole 22 can cover the sealing edge 113 of at least two pouch cell 11, thereby enabling pressure relief for at least two pouch cell 11. When any one or more pouch cell 11 experiences abnormal gas generation, the gas enters the same gas storage chamber with a larger volume after the sealing edge 113 ruptures. The gas storage chamber guides the gas flow to the same through hole 22 and finally discharges through the same through hole 22, thereby effectively improving the pressure relief efficiency, effectively ensuring the structural strength of the end plate 20, simplifying the structure of the end plate 20, and reducing the processing difficulty of the end plate 20.

[0105] like Figure 4 As shown, in one embodiment of this application, the extension length of the through hole 22 in the first direction is greater than its extension length in the third direction. That is, the length direction of the through hole 22 is the first direction, which is parallel to the arrangement direction of the battery. This can effectively shorten the distance between the sealing edge 113 of each soft-pack battery cell 11 and the corresponding through hole 22, thereby shortening the exhaust path, avoiding long-term accumulation of gas in the gas storage chamber, and improving exhaust efficiency.

[0106] Specifically, such as Figure 4 As shown, in one embodiment of this application, the total extension length of the through hole 22 in the first direction is L(2) mm; the extension length of the end plate 20 in the first direction is L(3) mm; L(2) / L(3) satisfies 0.12≤ L(2) / L(3) ≤0.8.

[0107] It is understandable that the extension length L(2) mm of the through hole 22 in the first direction can affect the coverage and exhaust capacity of the through hole 22; the extension length L(3) mm of the battery module in the second direction can affect the amount of gas produced by the soft-pack battery cell 11 when abnormal gas production occurs.

[0108] When the total extension length of the through hole 22 in the first direction is L(2) mm and the extension length of the end plate 20 in the first direction is L(3) mm, and L(2) / L(3) is less than 0.12, the coverage area of ​​the through hole 22 is too small, and the gas production of the soft-pack battery cell 11 is large when abnormal gas production occurs. The exhaust rate of the battery module in this embodiment is insufficient, which easily leads to gas accumulation. When L(2) / L(3) is greater than 0.8, the strength of the end plate 20 will be greatly weakened. Under vibration conditions, the end plate 20 is prone to deformation, and it will occupy too much installation space, reducing the energy density of the battery module.

[0109] Therefore, when L(2) / L(3) satisfies 0.12≤ L(2) / L(3) ≤0.8, the through hole 22 can quickly discharge the gas generated by the battery cell, and the internal pressure of the battery module will not increase significantly. At the same time, the end plate 20 can effectively fix the battery pack 10, effectively improve the structural strength of the end plate 20, save the installation space of the end plate 20, and improve the energy density of the battery module. In specific embodiments, the specific value of L(2) / L(3) can be selected from 0.12, 0.20, 0.33, 0.36, 0.40, 0.44, 0.48, 0.53, 0.58, 0.64, 0.8, etc., and is not limited here.

[0110] like Figure 4 As shown, in one embodiment of this application, the total extension length L(2) mm of the through hole 22 in the first direction satisfies 60 mm ≤ L(2) mm ≤ 200 mm.

[0111] When the total extension length L(2) mm of the through hole 22 in the first direction is less than 60 mm, the exhaust area of ​​the through hole 22 is too small and the exhaust rate is insufficient, which can easily lead to gas accumulation in the battery module of this application embodiment; when L(2) mm is greater than 200 mm, the area occupied by the through hole 22 on the end plate 20 is too large, which can easily lead to a decrease in the strength of the end plate 20 and make it impossible to effectively fix the battery pack 10.

[0112] Therefore, when the total extension length L(2) mm of the through hole 22 in the first direction satisfies 60 mm ≤ L(2) mm ≤ 200 mm, not only can gas be quickly discharged through the through hole 22, but the internal pressure of the battery module will not increase significantly. This also ensures that the end plate 20 has sufficient structural strength to effectively fix the battery pack 10. It effectively withstands vibration and impact, ensuring the safety and reliability of the battery module in use.

[0113] In a specific embodiment, the specific value of the extension length L(2) mm of the through hole 22 in the first direction can be selected from 60mm, 69mm, 79mm, 90mm, 103mm, 118mm, 135mm, 155mm, 177mm, 200mm, etc., and is not limited here. Specifically, when the total extension length L(2) mm of the through hole 22 in the first direction satisfies 60mm≤L(2) mm≤200mm, in order to make L(2) / L(3) satisfy 0.12≤L(2) / L(3)≤0.8, the extension length L(3) mm of the end plate 20 in the first direction can be in the range of 120mm≤L(3) mm≤500mm. In a specific embodiment, the specific value of the extension length L(3) mm of the end plate 20 in the first direction can be selected as 120mm, 141mm, 166mm, 195mm, 230mm, 270mm, 318mm, 374mm, 440mm, 500mm, etc., and is not limited here.

[0114] like Figure 8 and Figure 9 As shown, in one embodiment of this application, at least two through holes 22 are provided on the end plate 20 at intervals along the first direction, and the interval between adjacent through holes 22 in the first direction is L(4) mm, where L(4) mm satisfies 30 mm ≤ L(4) mm ≤ 80 mm.

[0115] When the distance L(4) mm between adjacent through holes 22 in the first direction is less than 30 mm, the solid area of ​​the end plate 20 between adjacent through holes 22 is too small, the end plate 20 is not strong enough and is prone to deformation; when L(4) mm is greater than 80 mm, the spacing between the coverage areas of each through hole 22 is large, and the sealing edge 113 of some battery cells cannot be covered by the through hole 22, which easily leads to poor exhaust.

[0116] Therefore, at least two through holes 22 are provided on the end plate 20 at intervals along the first direction. The interval between adjacent through holes 22 in the first direction is L(4) mm. When L(4) mm satisfies 30 mm≤L(4) mm≤80 mm, the structural strength of the end plate 20 can be effectively guaranteed, and structural deformation of the end plate 20 can be avoided. In addition, each through hole 22 on each end plate 20 can work independently and can cover more soft-pack battery cells 11, thereby ensuring smooth gas discharge and further reducing the risk of heat spread.

[0117] like Figure 8 and Figure 9 As shown, in one embodiment of this application, at least two protrusions 21 are provided on the end plate 20 in a first direction, and each through hole 22 is provided on the protrusion 21.

[0118] That is, on the end plate 20, each protrusion 21 has a through hole 22 on its bottom wall, and the through hole 22 corresponds one-to-one with the protrusion 21; the bottom wall of each protrusion 21 and the sealing edge 113 of the corresponding soft-pack battery cell 11 are spaced apart in the second direction to form a gas storage cavity, which further improves the pressure relief reliability and exhaust efficiency of the battery module in this embodiment; and, by providing at least two protrusions 21 on the end plate 20, the structural strength of the end plate 20 can be further enhanced.

[0119] like Figure 8 and Figure 9 As shown, in one embodiment of this application, in the first direction, a gap is formed between the through hole 22 and the edge of the protrusion 21; and in the first direction, the distance between adjacent protrusions 21 is L(5) mm, where L(5) mm satisfies 20 mm ≤ L(5) mm ≤ 50 mm.

[0120] Since there is a gap between the through hole 22 and the edge of the protrusion 21 in the first direction, it can be ensured that the through hole 22 will not extend to the edge of the protrusion 21, thereby effectively ensuring that the edge structure of the protrusion 21 is more complete and avoiding the through hole 22 from causing a reduction in the strength of the edge area of ​​the protrusion 21, thereby improving the structural strength of the protrusion 21.

[0121] Furthermore, in the first direction, if the distance L(5) mm between adjacent protrusions 21 is less than 20 mm, the interval between adjacent protrusions 21 is too small, which can easily lead to a reduction in the structural strength of the end plate 20; if L(5) mm is greater than 50 mm, a pressure relief blind zone can easily be formed between adjacent protrusions 21, resulting in poor ventilation of the soft-pack battery cell 11 in the middle region.

[0122] Therefore, in the first direction, the distance between adjacent protrusions 21 is L(5) mm. When L(5) mm satisfies 20 mm≤L(5) mm≤50 mm, it can ensure that the gas storage cavity formed by each protrusion 21 can cover more soft-pack battery cells 11, achieve good exhaust effect, and effectively improve the structural strength of the end plate 20, so that the end plate 20 is subjected to more uniform force, can better resist vibration and impact, and extend the service life of the battery module.

[0123] In one embodiment of this application, the protrusion 21 is open at least one end in the first direction. That is, the protrusion 21 extends directly to the end of the end plate 20 at least one end in the first direction without forming a separate sidewall. This effectively simplifies the processing of the protrusion 21 and, without affecting the structural strength of the end plate 20, effectively increases the coverage of the protrusion 21 and the corresponding gas storage cavity, so that the gas generated by the soft-pack battery cell 11 can be quickly collected in the gas storage cavity, thereby improving the exhaust efficiency.

[0124] Furthermore, in one embodiment of this application, at least two protrusions 21 are provided on the end plate 20 in a first direction; for each of the protrusions 21 located at both ends in the first direction, a sidewall is provided at one end adjacent to the other protrusions 21, and the end away from the other protrusions 21 is open.

[0125] That is, for each of the protrusions 21 located at both ends in the first direction, the end adjacent to other protrusions 21 is provided with a sidewall, and the end away from other protrusions 21 extends directly to the end of the end plate 20 without forming a separate sidewall. Thus, without affecting the structural strength of the end plate 20, the coverage of the protrusions 21 at both ends and the corresponding gas storage chamber is effectively increased, so that the gas generated by the soft-pack battery cell 11 can be quickly collected in the gas storage chamber, thereby improving the exhaust efficiency.

[0126] like Figures 8 to 12 As shown, in one embodiment of this application, a groove 23 is provided on at least one side of the protrusion 21 in the third direction on the end plate 20, with the groove opening facing the sealing edge. Since the groove 23 is provided on at least one side of the protrusion 21 in the third direction, and the groove opening faces the sealing edge, the groove 23 not only limits the position of the soft-pack battery cell 11, but also the groove 23 and the protrusion 21 together form a reinforcing rib structure, improving the structural strength of the end plate 20. It is understood that the groove 23 can be provided on the upper or lower side of the protrusion 21 in the third direction on the end plate 20, or simultaneously on both the upper and lower sides of the protrusion 21 in the third direction, thereby further improving the structural strength of the end plate 20.

[0127] Specifically, such as Figure 11As shown, in one embodiment of this application, the extension length of the groove 23 in the first direction is greater than the extension length of at least one protrusion 21 in the first direction.

[0128] Since the extension length of the groove 23 in the first direction is greater than the extension length of at least one protrusion 21 in the first direction, the groove 23 can become a through-hole on the end plate 20, while limiting the multiple soft-pack battery cells 11. Moreover, the groove 23 and at least one protrusion 21 together form a reinforcing rib structure, further improving the structural strength of the end plate 20.

[0129] like Figure 5 As shown, in one embodiment of this application, the end of the battery module in the third-party direction is the bottom end of the battery module, and the protrusion 21 is disposed on the end plate 20 near the bottom end of the battery module. That is, the third-party direction can be the height direction when the battery module is installed, with the end of the battery module in the third-party direction being the bottom end and the other end being the top end. Specifically, taking the center line of the end plate 20 in the third-party direction as a reference, the protrusion 21 is disposed below the center line of the end plate 20 in the third-party direction.

[0130] It is understandable that when the battery module is subjected to a bottom impact, the pouch cell 11 at the bottom is more prone to problems such as shell cracking and sealing edge 113 failure, which can lead to thermal runaway. Since the protrusion 21 is located on the end plate 20 near the bottom of the battery module, the gas storage cavity and through hole 22 formed therein can effectively contain the gas leaking from the bottom area of ​​the sealing edge 113 of the pouch cell 11 and quickly discharge the gas to the outside of the battery module, avoiding gas accumulation that could lead to thermal runaway. This further improves the pressure relief capability of the battery module in this embodiment and ensures the safety of the battery module in use.

[0131] like Figure 6 As shown, in one embodiment of this application, a conductive busbar is provided at least one end of the pouch cell 11 in the second direction; the conductive busbar is configured to electrically connect at least two pouch cell 11s, and the orthographic projection of the through hole 22 on the first end face 12 does not coincide with the orthographic projection of at least one conductive busbar on the first end face 12. Specifically, the electrode sheet 114 of at least one pouch cell 11 can be fixedly disposed on the conductive busbar, thereby realizing the electrical connection between at least two pouch cell 11s using the conductive busbar.

[0132] Understandably, when abnormal gas generation occurs in the pouch cell 11, the gas enters the gas storage chamber through the rupture of the sealing edge 113 and then exits the battery module through the through hole 22. Since the orthographic projection of the through hole 22 on the first end face 12 does not coincide with the orthographic projection of at least one conductive bar on the first end face 12, and their projections on the first end face 12 are completely misaligned, the gas can be discharged from the through hole 22 as quickly as possible and is less likely to flow to the vicinity of the conductive bar. This avoids high-temperature gas impacting the conductive bar and the electrode plates 114 on the conductive bar, effectively isolating the exhaust path from the power transmission path, and ensuring the electrical safety and operational stability of the battery module.

[0133] like Figure 6 As shown, in one embodiment of this application, the pouch cell 11 has an electrode sheet 114, which is configured to extend outward from the sealing edge 113 in a second direction; the orthographic projection of the through hole 22 on the first end face 12 does not coincide with the orthographic projection of the electrode sheet 114 of at least one pouch cell 11 on the first end face 12.

[0134] It is understandable that the electrode plate 114 of the pouch battery cell 11 is used to realize the electrical connection between the pouch battery cell 11 and the outside world. Since the orthographic projection of the through hole 22 on the first end face 12 and the orthographic projection of the electrode plate 114 of at least one pouch battery cell 11 on the first end face 12 do not coincide with each other, and the projections of the two on the first end face 12 are completely misaligned, the gas can be discharged from the through hole 22 as soon as possible and is not easy to flow to the vicinity of the electrode plate 114. This avoids the electrode plate 114 from melting or short-circuiting due to high temperature gas, effectively realizing the isolation between the exhaust path and the power transmission path, and ensuring the electrical safety and operational stability of the battery module.

[0135] Specifically, such as Figure 5 As shown, in one embodiment of this application, the electrode sheet 114 includes a first electrode sheet 1141 and a second electrode sheet 1142, the first electrode sheet 1141 and the second electrode sheet 1142 having opposite polarities; for the region where the orthographic projection of the protrusion 21 on the first end face 12 overlaps with the orthographic projection of the first electrode sheet 1141 of at least one soft-pack battery cell 11 on the first end face 12, the protrusion width H mm of the protrusion 21 in the second direction is ≥2.5 mm.

[0136] It is understandable that the first electrode 1141 and the second electrode 1142 can serve as the positive and negative output terminals of the pouch cell 11, respectively. When the first electrode 1141 is the positive output terminal, it is usually made of aluminum, which has a relatively low melting point. When the second electrode 1142 is the negative output terminal, it is usually made of copper, which has a relatively high melting point.

[0137] Therefore, when the first electrode sheet 1141 includes aluminum, for the area where the orthographic projection of the protrusion 21 on the first end face 12 and the orthographic projection of the first electrode sheet 1141 of the soft-pack battery cell 11 overlap, if the protrusion width H mm ≥ 2.5 mm in the second direction of the protrusion 21 can effectively increase the thickness of the gas storage cavity formed by the area of ​​the protrusion 21 corresponding to the first electrode sheet 1141, thereby improving the exhaust capacity of the area corresponding to the first electrode sheet 1141, ensuring smooth exhaust, avoiding heat and gas accumulation, and further improving the reliability and service life of the battery module.

[0138] like Figure 6 As shown, in one embodiment of this application, in the third direction, there is a gap between the through hole 22 and the electrode sheet 114 of the soft-pack battery cell 11, and the extension length of the gap between the through hole 22 and the electrode sheet 114 of the soft-pack battery cell 11 in the third direction is L(6) mm, and L(6) mm satisfies 5mm≤L(6) mm≤50 mm.

[0139] Because there is a gap between the through hole 22 and the electrode plate 114 of the soft-pack battery cell 11 in the third direction, the gas generated by the soft-pack battery cell 11 can be discharged from the through hole 22 as soon as possible and is not easy to flow to the vicinity of the electrode plate 114. This avoids the electrode plate 114 from melting or short-circuiting due to high temperature gas, effectively achieving the isolation between the exhaust path and the power transmission path, and ensuring the electrical safety and operational stability of the battery module.

[0140] When the distance between the through hole 22 and the electrode plate 114 of the soft-pack battery cell 11 is less than 5 mm in the third direction extension length L(6) mm, the distance between the two is small, and the high temperature gas generated by the soft-pack battery cell 11 may still cause the electrode plate 114 to melt or short-circuit. When the distance between the through hole 22 and the electrode plate 114 of the soft-pack battery cell 11 is greater than 50 mm in the third direction extension length L(6) mm, the size of the electrode plate 114 is too small, which may affect the current carrying capacity of the electrode plate 114, or require an increase in the space occupied by the electrode plate 114, thus affecting the energy density of the battery module in this application embodiment.

[0141] Therefore, when the distance between the through hole 22 and the electrode sheet 114 of the soft-pack battery cell 11 extends L(6) mm in the third direction and satisfies 5mm≤L(6) mm≤50 mm, it can effectively prevent the high-temperature gas generated by the soft-pack battery cell 11 from causing the electrode sheet 114 to melt or short-circuit, ensuring the safety of electrical transmission, ensuring the overcurrent capacity of the electrode sheet 114, reducing the overcurrent resistance of the soft-pack battery cell 11, and improving the energy density of the battery module in this embodiment.

[0142] In a specific embodiment, the specific value of the extension length L(6) mm of the distance between the through hole 22 and the electrode sheet 114 of the soft-pack battery cell 11 in the third direction can be selected from specific values ​​such as 5mm, 6mm, 7mm, 9mm, 11mm, 14mm, 17mm, 22mm, 29mm, 50mm, etc., and is not limited here.

[0143] like Figure 4 As shown, in one embodiment of this application, the end plate 20 has a dimension L(3) mm ≥ 400 mm in the first direction, and the through hole 22 has an extension length L(2) mm ≥ 35 mm in the first direction.

[0144] That is, when the dimension L(3) mm of the end plate 20 in the first direction is greater than or equal to 400 mm, by making the extension length L(2) mm of the through hole 22 in the first direction greater than or equal to 35 mm, it can be ensured that the exhaust area of ​​the through hole 22 can meet the requirements, the gas can be quickly discharged through the through hole 22, and the internal pressure of the battery module will not increase significantly, thus ensuring the safety and reliability of the battery module.

[0145] like Figure 4 As shown, in one embodiment of this application, a partition plate 30 is provided between the end plate 20 and the battery pack 10; a weak part 31 is provided on the partition plate 30, and the orthographic projection of the weak part 31 on the first end face 12 is located inside the orthographic projection of the through hole 22 on the first end face 12.

[0146] Specifically, the end plate 20 can be a metal plate. In order to prevent a short circuit between the end plate 20 and the battery pack 10, a separator 30 can be provided between the end plate 20 and the battery pack 10. The separator 30 serves as an insulator.

[0147] Because the partition plate 30 is provided with a weak part 31, and the orthographic projection of the weak part 31 on the first end face 12 is located inside the orthographic projection of the through hole 22 on the first end face 12, the gas generated by the soft-pack battery cell 11 can flow through the weak part 31 to the through hole 22. Finally, the gas is discharged to the outside of the battery module through the through hole 22, completing the pressure relief process. This avoids the severe thermal runaway and heat propagation caused by the accumulation of internal pressure in the battery module, significantly improving the safety of the battery module. Furthermore, the weak part 31 can not only ensure the smooth passage of gas, but also play a role in preventing foreign objects and water and gas, further improving the electrical safety and protection of the battery module.

[0148] The material of the separator can include one or more of epoxy resin, polyester resin, phenolic resin, polyvinyl chloride, mica board, etc., and is not limited thereto. Specifically, the weak part 31 can be a region that is thinner than the body area of ​​the separator 30, or it can be a gap or groove provided on the separator 30, so that the gas generated by the soft-pack battery cell 11 can flow through the weak part 31 to the through hole 22, and finally the gas is discharged to the outside of the battery module through the through hole 22.

[0149] This application also provides a battery pack, which includes at least one of the aforementioned battery modules. Specifically, the battery pack of this application embodiment, as a rechargeable battery, can serve as a power source for electrical equipment such as new energy vehicles.

[0150] Specifically, the battery pack in this embodiment is a complete functional unit that can directly output electrical energy, consisting of the aforementioned battery module, battery management system (BMS), thermal management system, electrical connection system (high-voltage / low-voltage connectors, wiring harnesses, etc.), structural components (shell, brackets, etc.), and protective components, all housed within a casing and sealed with a cover. The casing generally includes a base plate and a frame, and the base plate, frame, and cover are typically made of high-strength materials such as aluminum alloy, stainless steel, or plastic.

[0151] This application also provides an electrical device, which includes the aforementioned battery pack or battery module. It is understood that this electrical device can be various types of electrical devices such as energy storage devices, electric ships, aircraft, laptops, power tools, electric bicycles, electric motorcycles, and electric vehicles. The aforementioned battery pack or battery module can serve as the operating power source or the driving power source for the electrical device, replacing or partially replacing fuel or natural gas to provide driving power for vehicles. It is applicable to numerous fields such as civilian use, military equipment, and aerospace, and is not limited thereto.

[0152] It should be noted that the elements described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0153] It should be understood that multiple components and / or portions can be provided by a single integrated component or portion. Alternatively, a single integrated component or portion can be divided into multiple separate components and / or portions. The use of the disclosure "a" or "an" to describe a component or portion does not exclude other components or portions. It should be understood that while terms such as "first" or "second" may be used in this application to describe various elements, these elements are not limited by these terms, which are merely used to distinguish one element from another. The terminology used in one or more embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit one or more embodiments of this application. The singular forms "a," "the," and "the" as used in one or more embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used in one or more embodiments of this application refers to and includes any or all possible combinations of one or more associated listed items.

[0154] In this document, terms such as "up," "down," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, and not to define the absolute position of these related parts. Terms such as "equal" and "same" are not strict mathematical and / or geometric limitations, and also include errors that are understandable to those skilled in the art and permissible in manufacturing or use. Unless otherwise stated, numerical ranges in this document include not only the entire range within its two endpoints, but also several subranges contained therein.

[0155] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0156] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery module, characterized in that, include: The battery pack (10) includes at least two pouch battery cells (11) arranged along a first direction. The battery pack (10) has two opposing first end faces (12). The outer shell of the pouch battery cell (11) includes a first shell (111) and a second shell (112) disposed opposite to each other. The first shell (111) and the second shell (112) are bonded together to form a sealing edge (113). At least one end plate (20) is disposed on the first end face (12) of the battery pack (10), and the sealing edge (113) is disposed opposite to the end plate (20). The end plate (20) is provided with a protrusion (21) protruding in a direction away from the battery pack (10), and a through hole (22) is provided on the bottom wall of the protrusion (21). The orthographic projection of the through hole (22) on the first end face (12) at least partially coincides with the orthographic projection of the sealing edge (113) of at least one of the soft-pack battery cells (11) on the first end face (12). The bottom wall of the protrusion (21) and the sealing edge (113) of the soft-pack battery cell (11) are spaced apart in a second direction to form an air storage cavity between the bottom wall of the protrusion (21) and the sealing edge (113) of the soft-pack battery cell (11), and the second direction is perpendicular to the first end face (12).

2. The battery module according to claim 1, characterized in that, The sealing edge (113) extends L(1) mm in the second direction, and the protrusion of the protrusion (21) in the second direction is H mm. L(1)×H satisfies 16≤L(1)×H≤300.

3. The battery module according to claim 2, characterized in that, The extension width L(1) mm of the sealing edge (113) in the second direction satisfies 6 mm ≤ L(1) mm ≤ 35 mm; And / or, the protrusion width H mm of the protrusion (21) in the second direction satisfies 2 mm ≤ H mm ≤ 10 mm.

4. The battery module according to claim 1, characterized in that, The first direction is perpendicular to the second direction, and the third direction is a direction that is perpendicular to both the second direction and the first direction. The extension length of the pouch cell (11) in the second direction is greater than the extension length in the first direction and greater than the extension length in the third direction.

5. The battery module according to claim 1, characterized in that, The outer casing of the soft-pack battery cell (11) has a first surface (15) which is arranged parallel to the first end face (12), and the sealing edge (113) is configured to extend outward from the first surface (15) along the second direction.

6. The battery module according to claim 5, characterized in that, The outer casing of the soft-pack battery cell (11) has two opposing first surfaces (15) at both ends in the second direction, and the two opposing first surfaces (15) are provided with the sealing edge (113).

7. The battery module according to claim 6, characterized in that, The battery module has two end plates (20), which are respectively disposed on the two first end faces (12) of the battery pack (10), and the through holes (22) of the two end plates (20) are respectively disposed corresponding to the sealing edge (113) of the opposite soft-pack battery cell (11).

8. The battery module according to claim 1, characterized in that, The through hole (22) of the end plate (20) is provided corresponding to the sealing edge (113) of at least two opposite pouch cell (11).

9. The battery module according to claim 8, characterized in that, The first direction is perpendicular to the second direction, and the third direction is a direction that is perpendicular to both the second direction and the first direction. The through hole (22) extends longer in the first direction than it extends in the third direction.

10. The battery module according to claim 9, characterized in that, The total extension length of the through hole (22) in the first direction is L(2) mm; the dimension of the end plate (20) in the first direction is L(3) mm; L(2) / L(3) satisfies 0.12≤ L(2) / L(3) ≤0.

8.

11. The battery module according to claim 9, characterized in that, The total extension length L(2) mm of the through hole (22) in the first direction satisfies 60 mm ≤ L(2) mm ≤ 200 mm.

12. The battery module according to claim 9, characterized in that, At least two through holes (22) are provided on the end plate (20) at intervals along the first direction. The interval between adjacent through holes (22) in the first direction is L(4) mm, and L(4) mm satisfies 30 mm≤L(4) mm≤80 mm.

13. The battery module according to claim 12, characterized in that, At least two protrusions (21) are provided on the end plate (20) in the first direction, and each through hole (22) is provided on the protrusion (21).

14. The battery module according to claim 13, characterized in that, In the first direction, a gap is formed between the through hole (22) and the edge of the protrusion (21); Furthermore, in the first direction, the distance between adjacent protrusions (21) is L(5) mm, where L(5) mm satisfies 20 mm ≤ L(5) mm ≤ 50 mm.

15. The battery module according to any one of claims 1 to 14, characterized in that, The protrusion (21) is open at at least one end in the first direction.

16. The battery module according to claim 15, characterized in that, At least two protrusions (21) are provided on the end plate (20) in the first direction. For at least one of the protrusions (21) located at both ends in the first direction, a sidewall is provided at one end adjacent to the other protrusions (21), and the end away from the other protrusions (21) is open.

17. The battery module according to any one of claims 1 to 14, characterized in that, The first direction is perpendicular to the second direction, and the third direction is a direction that is perpendicular to both the second direction and the first direction. On the end plate (20), the protrusion (21) is provided with a groove (23) on at least one side in the third direction, and the groove (23) is oriented toward the sealing edge.

18. The battery module according to claim 17, characterized in that, The extension length of the groove (23) in the first direction is greater than the extension length of at least one of the protrusions (21) in the first direction.

19. The battery module according to any one of claims 1 to 14, characterized in that, The first direction is perpendicular to the second direction, and the third direction is a direction that is perpendicular to both the second direction and the first direction. The bottom end of the battery module is located at the third-direction upward end, and the protrusion (21) is disposed on the end plate (20) near the bottom end of the battery module.

20. The battery module according to any one of claims 1 to 14, characterized in that, The pouch cell (11) has a conductive bus at at least one end in the second direction, and the conductive bus is configured to electrically connect at least two pouch cells (11). The orthographic projection of the through hole (22) on the first end face (12) does not coincide with the orthographic projection of at least one of the conductive bars on the first end face (12).

21. The battery module according to any one of claims 1 to 14, characterized in that, The pouch cell (11) has an electrode sheet (114) configured to extend outward from the sealing edge (113) in the second direction; The orthographic projection of the through hole (22) on the first end face (12) does not coincide with the orthographic projection of the electrode sheet (114) of at least one of the soft-pack battery cells (11) on the first end face (12).

22. The battery module according to claim 21, characterized in that, The electrode sheet (114) includes a first electrode sheet (1141) and a second electrode sheet (1142), the first electrode sheet (1141) and the second electrode sheet (1142) have opposite polarities, and the first electrode sheet (1141) includes aluminum; For the region where the orthographic projection of the protrusion (21) on the first end face (12) and the orthographic projection of the first electrode sheet (1141) of the soft-pack battery cell (11) on the first end face (12) overlap, the protrusion width H mm of the protrusion (21) in the second direction is ≥2.5 mm.

23. The battery module according to any one of claims 1 to 14, characterized in that, The first direction is perpendicular to the second direction, and the third direction is a direction that is perpendicular to both the second direction and the first direction. In the third direction, there is a gap between the through hole (22) and the electrode sheet (114) of the soft-pack battery cell (11), and the extension length of the gap between the through hole (22) and the electrode sheet (114) of the soft-pack battery cell (11) in the third direction is L(6) mm, and L(6) mm satisfies 5mm≤L(6) mm≤50 mm.

24. The battery module according to any one of claims 1 to 14, characterized in that, The first direction is perpendicular to the second direction; The end plate (20) has a dimension L(3) mm ≥ 400 mm in the first direction, and the through hole (22) has an extension length L(2) mm ≥ 35 mm in the first direction.

25. The battery module according to any one of claims 1 to 14, characterized in that, A partition plate (30) is provided between the end plate (20) and the battery pack (10). The partition plate (30) is provided with a weak part (31), and the orthographic projection of the weak part (31) on the first end face (12) is at least partially located inside the orthographic projection of the through hole (22) on the first end face (12).

26. The battery module according to any one of claims 1 to 14, characterized in that, The outer shell of the soft-pack battery cell (11) includes an inner sealing layer, an intermediate metal layer and an outer insulating layer; the inner sealing layer of the first shell (111) and the inner sealing layer of the second shell (112) are bonded together.

27. A battery pack, characterized in that, It includes at least one battery module according to any one of claims 1 to 26.

28. An electrical appliance, characterized in that, It includes at least one battery module according to any one of claims 1 to 26, or a battery pack according to claim 27.

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