Battery pack and electric device

Abstract

The application relates to the new energy technology field and discloses a battery pack and a power utilization device, the battery pack comprising: a soft package battery, the soft package battery comprising a battery core and a shell body for packaging the battery core, the shell body comprising a shell main body and an edge formed on both sides of the shell main body along a third direction, the edge being arranged to protrude from a first end surface of the shell main body along a first direction to form a first protruding part; the first direction being perpendicular to the first end surface; the first end surface and the first protruding parts located at both ends of the first end surface along the third direction jointly defining a recessed area; a supporting piece, at least partially arranged in the recessed area; and the third direction being perpendicular to the first direction. The battery pack provided by the application has the supporting piece arranged at least partially in the recessed area to fill the space gap between the first protruding part and the first end surface. After a plurality of soft package batteries are stacked to form the battery pack, the flatness of the bottom surface of the battery pack is guaranteed, and the assembly efficiency and the use safety of the battery pack are improved.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, specifically to a battery pack and an electrical device. Background Technology

[0002] Soft-pack batteries have simple structures and low costs, and are widely used in the new energy field. However, in actual use, it has been found that the flatness of the bottom surface of soft-pack batteries is poor, which affects the assembly efficiency between the battery pack and the battery assembly. Summary of the Invention

[0003] In view of this, the present invention provides a battery pack and an electrical device to solve the problem that the poor flatness of the bottom surface of a pouch battery affects assembly efficiency.

[0004] In a first aspect, the present invention provides a battery pack, comprising:

[0005] A pouch battery includes a cell and a housing for encapsulating the cell. The housing includes a main body and sealing edges formed on both sides of the main body along a third direction. The sealing edges protrude from a first end face of the main body along a first direction to form a first protrusion. The first direction is perpendicular to the first end face.

[0006] The first end face and the first protrusions located at both ends of the first end face along the third direction together define a recessed area;

[0007] The support member is at least partially disposed within the recessed area;

[0008] The third direction is perpendicular to the first direction.

[0009] Beneficial effects: The support member is at least partially disposed within the recessed area to fill the spatial gap between the first protrusion and the first end face. This ensures the flatness of the bottom surface of the pouch battery, and further ensures the flatness of the bottom surface of the battery pack after multiple pouch batteries are stacked to form a battery pack, thereby improving the assembly efficiency and safety of the battery pack.

[0010] Secondly, the present invention also provides an electrical device, comprising:

[0011] The main body of the electrical device, and the battery pack electrically connected to the main body of the electrical device.

[0012] Since the electrical device includes a battery pack and has the same effect as the battery pack, it will not be elaborated on here. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a perspective view of the battery pack of the present invention;

[0015] Figure 2 This is a side view of the battery pack of the present invention;

[0016] Figure 3 for Figure 2 A magnified view of a portion of the image;

[0017] Figure 4 This is a perspective view of the soft-pack battery of the present invention;

[0018] Figure 5 for Figure 4 Enlarged view of point A in the middle;

[0019] Figure 6 This is a side view of the soft-pack battery of the present invention;

[0020] Figure 7 This is a schematic diagram of the housing of the present invention before sealing.

[0021] Explanation of reference numerals in the attached figures:

[0022] 1. Soft-pack battery; 12. Casing; 121. Casing body; 122. Edge sealing; 1221. First protrusion; 1201. First end face; 1202. Second end face; 123. Recessed area; 124. Transition part;

[0023] 2. Support components. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] Soft-pack batteries have simple structures and low costs, and are widely used in the new energy field. However, in actual use, it has been found that the flatness of the bottom surface of soft-pack batteries is poor, which affects the assembly efficiency between the battery pack and the battery assembly.

[0029] Research has found that during the sealing process of pouch batteries, after the battery casing is sealed, the sealed edge protrudes outward relative to the main body of the casing. As a result, when multiple pouch batteries are stacked to form a battery pack, the flatness of the battery pack end face is poor, which affects the assembly efficiency of the battery pack.

[0030] To facilitate understanding of the technical solution of this application, several technical terms that may be involved in this application will first be explained:

[0031] Battery pack:

[0032] Multiple soft-pack battery cells with similar capacity and internal resistance are connected in series or in parallel to form a battery pack.

[0033] Shell 12:

[0034] The casing of a pouch battery is a multi-layered structure consisting of an outer insulating layer, a metal layer, and an inner insulating layer. The outer insulating layer can be made of one or more materials such as polycaprolactam (nylon 6), PET (polyethylene terephthalate), or polybutylene succinate. The metal layer can be made of one or more metals or alloys such as aluminum, aluminum alloy, copper, or nickel. The inner insulating layer can be made of one or more materials such as polypropylene film (PP) or cast polypropylene film (CPP).

[0035] Battery cell:

[0036] A battery cell is the component in a battery where electrochemical reactions occur; it is the smallest unit in a battery capable of performing electrochemical reactions such as charging and discharging. A battery cell is the basic unit of a battery and typically includes a positive electrode, a negative electrode, and a separator. Lithium-ion battery cells primarily function by the movement of lithium ions between the positive and negative electrodes. In cylindrical cells, a three-layer thin-film structure is wound into a cylindrical electrode assembly, while in cuboid cells, the thin-film structure is wound or stacked into an electrode assembly with a roughly cuboid shape.

[0037] Extreme film:

[0038] Including positive and negative electrodes, let's first talk about the positive electrode:

[0039] The positive electrode is one of the core components in a battery that carries the positive electrode active material. During charging, metal ions (such as 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 (such as 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 electrode active materials in batteries. These positive active materials can be used alone or in combination. Lithium phosphates include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., 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, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide (e.g., LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3O2 (Also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25O2 (Also known as NCM211), LiNi 0.6 Co 0.2 Mn 0.2O2 (Also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1O2 (Also known as NCM811)), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05O2 At least one of the following: ) and its modified compounds.

[0041] 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.

[0042] 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.

[0043] Secondly, regarding the negative electrode:

[0044] During battery charging, active ions (such as Li) from the positive electrode are embedded in the negative electrode, while electrons from the positive electrode are transferred to the negative electrode through an external circuit to maintain charge balance. During discharge, active ions (such as Li) previously embedded in the negative electrode can be released, while electrons from the negative electrode are transferred to the positive electrode through an external circuit to maintain charge balance, thus achieving energy storage and release.

[0045] The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector is a conductive metal foil, which can be made of stainless steel, copper, aluminum, nickel, carbon electrodes, or titanium with a silver-plated surface. The composite current collector may include a polymer material base layer 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 material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). The negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder.

[0046] 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-nitrogen composites. The conductive agent can be conductive carbon black, carbon nanotubes, etc., and the binder can be styrene-butadiene rubber, polyacrylic acid, etc.

[0047] Fixing plate:

[0048] A fixing plate is disposed on at least one surface of the pouch battery pack to constrain the pouch battery. Since the pouch battery casing is a thin-film structure with relatively low strength, the fixing plate is needed to constrain the pouch battery during charging and discharging to prevent excessive expansion. In addition, the fixing plate also protects the pouch battery from direct external impacts and pressure on its relatively weak casing, thus reinforcing the safety of the battery pack.

[0049] The mounting plate can be made of copper, iron, aluminum, steel, stainless steel, aluminum alloy, plastic, or other metal materials or composite materials of metal and non-metal; it can be made of engineering plastics, fiberglass, or carbon fiber; it can be made of aluminum alloy sheet through extrusion and / or machine tool processing. The common structure is a flat plate structure with a certain thickness, usually 2mm to 25mm, which can meet the strength requirements of the battery device. When the thickness is too small, it cannot meet the structural strength requirements, and when the thickness is too large, it affects the energy density of the battery device.

[0050] Support component 2:

[0051] Support component 2 can specifically be a metal fastening strap, used to secure the surface of the pouch battery pack where no fixing plate is installed. The metal fastening strap does not completely cover the surface; it is also used when a portion of the pouch battery casing needs to be exposed for subsequent installation of a heat exchange structure. The metal fastening strap is fixed to the fixing plate, and the fixing methods include, but are not limited to, welding, riveting, and screwing.

[0052] Typically, a strip of metal is used, and the material can be copper, iron, aluminum, steel, stainless steel, aluminum alloy, etc. It is preferred that the same material be used as the fixing plate.

[0053] To prevent short circuits caused by overlapping between the metal fastening strap and the pouch battery casing, an insulating protective layer can be provided at least on the end of the metal fastening strap facing the pouch battery casing. This can be achieved by using insulating components, insulating films, or insulating spraying processes to create the insulating protective layer.

[0054] Examples of insulating film compositions include: polyester film (PET, Polyethylene Terephthalate), polyimide (PI), polypropylene (PP), or polyethylene (PE).

[0055] Examples of insulating coating components: (1) modified epoxy resin; (2) polyacrylate; (3) polyethylene phthalate (PET); (4) insulating materials include oil-based insulating resin or water-based insulating resin as the main materials. The main materials of insulating resin include epoxy resin, acrylic resin, polyurethane resin, hydroxyl acrylic resin and other multifunctional resins; various additives may also be included in insulating materials, such as photoinitiators, reactive diluents, flame retardants, wetting agents, leveling agents, defoamers, etc.; (5) polyimide coating or insulating coating formed by polymers such as polyimide (PI) and epoxy resin; (6) styrene-butadiene rubber latex.

[0056] The molding and sealing process for the housing is as follows:

[0057] (1) Molding process. Cut the initial sheet material according to the design dimensions of the shell. Using a molding die, under heating, punch out recesses on the initial sheet material to accommodate the core, forming the initial packaging shell. The depth and number of recesses need to be determined according to the thickness of the battery cell. Generally, a single recess is chosen when the battery cell is thin, and a double recess is chosen when the battery cell is thick. (2) Top and side sealing process. First, place the wound core into the punched recesses, and then fold the initial packaging shell in half along the fold line. Place the packaging shell and the core into the fixture, and perform top and side sealing in the top and side sealing machine. During sealing, the two sealing heads have a certain temperature. When they are closed, they are pressed on the packaging shell, and the PP layer of the packaging shell melts and sticks together, completing the sealing.

[0058] The following is combined with Figures 1 to 7 The following describes embodiments of the present invention.

[0059] According to an embodiment of the present invention, in one aspect, a battery pack is provided, comprising:

[0060] The soft-pack battery 1 includes a battery cell and a housing 12 for encapsulating the battery cell. The housing 12 includes a housing body 121 and sealing edges 122 formed on both sides of the housing body 121 along a third direction. The sealing edges 122 are provided to protrude from a first end face 1201 of the housing body 121 along a first direction to form a first protrusion 1221. The first direction is perpendicular to the first end face 1201.

[0061] The first end face 1201 and the first protrusions 1221 located at both ends of the first end face 1201 along a third direction together define a recessed region 123;

[0062] Support member 2 is at least partially disposed within the recessed area 123;

[0063] The third direction is perpendicular to the first direction.

[0064] The battery pack in this embodiment is formed by stacking multiple pouch batteries 1 along the second direction. The pouch battery 1 refers to a battery that uses a soft outer shell as the encapsulation material. For example, the shell 12 of the pouch battery 1 includes an aluminum-plastic film, which includes a multi-layer structure composed of an outer nylon layer, an intermediate metal layer and an inner heat-sealing layer.

[0065] The soft-pack battery 1 has a battery cell inside its casing 12. The battery cell includes multiple stacked electrodes, with a separator between the electrodes to achieve electrical isolation. The battery cell is connected to an external circuit through tabs.

[0066] In this embodiment, the pouch battery 1 is constructed in a cuboid shape, and the battery pack is formed by stacking multiple pouch batteries 1 along a second direction. The second direction can be consistent with the thickness direction of the pouch battery 1, thereby effectively improving the energy density of the battery pack during stacking.

[0067] The housing 12 includes a housing body 121 and sealing edges 122 formed on both sides of the housing body 121 along a third direction. The sealing edges 122 are formed by heat sealing process from the edges of the housing body 121 to seal the battery cell to prevent electrolyte leakage.

[0068] Combination Figure 5 As shown, the sealing edge 122 protrudes from the first end face 1201 of the shell body 121 along the first direction to form a first protrusion 1221. Since the area of ​​the shell body 121 corresponding to the battery cell is thicker, while the sealing edge area has no battery cell structure, the thickness is significantly reduced after heat sealing, resulting in a step difference between the sealing edge 122 and the shell body 121, which forms the first protrusion 1221.

[0069] The first protrusion 1221 protrudes from the first end face 1201 of the shell body 121 along the first direction. The first end face 1201 and the first protrusion 1221 located at both ends of the first end face 1201 along the third direction together define the recessed area 123. That is, when the shell body 121 is placed on a plane, the first end face 1201 is positioned opposite to the placement plane. At this time, the first protrusions 1221 on both sides form a fulcrum with the placement plane. The spatial gap between the first end face 1201 and the placement plane in the first direction is the recessed area 123.

[0070] This embodiment further includes a support member 2, which is at least partially disposed within the recessed area 123 to fill the spatial gap between the first protrusion 1221 and the first end face 1201. This ensures the flatness of the bottom surface of the pouch battery and further ensures the flatness of the bottom surface of the battery pack after multiple pouch batteries 1 are stacked to form a battery pack, thereby improving the assembly efficiency and safety of the battery pack.

[0071] In this embodiment, the first direction is the width direction of the pouch battery 1, the second direction is the thickness direction of the pouch battery 1, and the third direction is the length direction of the pouch battery 1. That is, the first direction is the height direction of the battery pack, the third direction is the length direction of the battery pack, and the second direction corresponds to the width direction of the battery pack.

[0072] Optionally, support member 2 may be made of a flexible insulating material. Support member 2 may also be made of metal or a combination of multiple materials.

[0073] In some embodiments, combined with Figure 2 As shown, the shell body 121 has sealing edges 122 at both ends along the third direction, and the sealing edges 122 at both ends are formed with first protrusions 1221.

[0074] The recessed area 123 is located between the first protrusions 1221 at both ends along a third direction.

[0075] Combination Figure 7As shown, the housing 12 is in an unfolded state before sealing. The housing 12 includes two perforations, and the housing 12 is folded along the folding center line S between the two perforations. After folding, the sealing edges A1 and B1 of the housing are aligned, the sealing edges A2 and B2 are aligned, and the sealing edges A3 and B3 are aligned. The aligned sealing edges are then heat-pressed to achieve a seal.

[0076] Wherein, sealing edge A1 and B1, after sealing, form a sealing edge 122 along the third direction on one side, and sealing edge A3 and B3, after sealing, form a sealing edge 122 along the third direction on the other side. A first protrusion 1221 is formed on the shell surface D corresponding to the folded center line S.

[0077] The shell body 121 has sealing edges 122 at both ends along the third direction. Since the area of ​​the shell body 121 corresponding to the battery cell is thicker, while the sealing edge area at both ends along the third direction has no battery cell structure, the thickness is significantly reduced after heat sealing, resulting in a step difference between the sealing edge 122 and the shell body 121, that is, a first protrusion 1221 is formed at both ends along the third direction.

[0078] The first protrusions 1221 at both ends protrude from the first end face 1201 of the shell body 121 along the first direction, and the first protrusions 1221 at both ends and the first end face 1201 together define the recessed area 123.

[0079] The support member 2 is at least partially disposed within the recessed area 123 to fill the recessed area 123 and ensure the overall flatness of the stacked battery pack.

[0080] In some embodiments, the thickness of the portion of the support member 2 that overlaps with the recessed region 123 along the first direction is greater than or equal to the protrusion height of the first protrusion 1221 along the first direction.

[0081] The thickness of the support member 2 along the first direction is greater than the height of the first protrusion 1221, which can fully fill the recessed area 123, ensure the flatness of the battery pack end face, and avoid the overall flatness after stacking being insufficient due to the support member 2 being flush with or slightly recessed with the first end face 1201, thus affecting the assembly accuracy and structural strength.

[0082] In some embodiments, the thickness of the portion of the support member 2 that overlaps with the recessed region 123 along the first direction is dmm, and the protrusion height of the first protrusion 1221 along the first direction is hmm, satisfying: 0mm≤dmm-hmm≤9.7mm.

[0083] By limiting the lower limit of the difference between the thickness d of the support member 2 along the first direction and the height h of the first protrusion 1221 along the first direction, it is ensured that the support member 2 can effectively fill the recessed area 123 after assembly, thus ensuring the flatness of the battery pack end face. At the same time, by limiting the upper limit of the difference between the thickness d of the support member 2 along the first direction and the height h of the first protrusion 1221 along the first direction, it is avoided that the support member 2 excessively squeezes the soft-pack battery due to an excessive difference, which may cause cell deformation or internal short circuit risk. It is also avoided that the support member 2 protrudes excessively from the first end face 1201, which may cause the battery pack to interfere with other components during stacking or installation, thus avoiding affecting the space utilization rate.

[0084] In this embodiment, the value of d ranges from 1.2mm to dmm to 10mm.

[0085] In this embodiment, the value of h ranges from 0.3mm to hmm to 5mm.

[0086] In this embodiment, the value range of dmm-hmm is 0mm≤dmm-hmm≤9.7mm; as a further preferred embodiment, the value range of dmm-hmm is 0mm≤dmm-hmm≤5mm.

[0087] When the value of dmm-hmm is less than 0mm, the pouch battery mainly relies on the first protrusion 1221 to support its weight. A cavity exists in the middle of the battery, and the middle of the cell tends to sag and deform, leading to compression of the middle cell and causing lithium plating and material loss, thus affecting the battery's cycle life. Conversely, when the value of dmm-hmm is too large, the position of the cell relative to the support bears the battery's weight, also causing compression at the support's location.

[0088] For example, in this embodiment, the value of dmm-hmm can be 0mm or 1mm or 2mm or 3mm or 4mm or 5mm or 6mm or 7mm or 8mm or 9mm or 9.7mm, or it can be a range formed by any two of the above values.

[0089] It should be noted that the measurement methods for dmm and hmm are as follows: Use measuring instruments such as micrometers or calipers to measure parameters such as length, width, distance, and thickness.

[0090] The battery pack fabrication method in this embodiment is as follows:

[0091] (1) Preparation of the positive electrode:

[0092] 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, air-dried at room temperature, and then transferred to an oven for further drying. Finally, it is cold-pressed and slit to obtain the positive electrode sheet. Specifically, the mass ratio of positive electrode active material: conductive agent: binder satisfies (92~98):(4~1):(4~1).

[0093] (2) Preparation of negative electrode:

[0094] The negative electrode active material, conductive agent acetylene black, thickener CMC, and binder SBR are mixed, and deionized water is added as a 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, air-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).

[0095] (3) Preparation of electrolyte:

[0096] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, fully dried lithium salt LiPF6 was dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0097] (4) Preparation of the diaphragm:

[0098] Polyethylene film is selected as the diaphragm.

[0099] (5) Preparation of pouch cells:

[0100] The positive electrode, separator, and negative electrode are stacked in sequence to form a bare battery cell. This bare cell is then placed in a pouch battery casing made of aluminum-plastic film. The first inner insulating layer of the aluminum-plastic film casing is made of cast polypropylene film (CPP), the second metal layer is made of aluminum, and the third outer insulating layer is made of polycaprolactam (nylon 6). The battery is dried, injected with electrolyte, and then encapsulated, allowed to stand, formed, and volume-adjusted to obtain the pouch battery.

[0101] 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.

[0102] (6) Battery pack assembly:

[0103] Multiple pouch batteries are connected in series or parallel, and the support is placed in the recessed area to form a battery pack.

[0104] Referring to Table 1 below, the capacity retention rate of the provided battery pack was tested through several embodiments and comparative tests to verify its qualification.

[0105] Table 1

[0106]

[0107] Regarding Table 1 above, the explanation is as follows:

[0108] Performance 1, Battery pack capacity retention rate test, the method is as follows:

[0109] Following the aforementioned battery pack fabrication method, corresponding pouch cells were prepared for each embodiment and comparative example, with consistent cell dimensions across all pouch cells. Twelve pouch cells were connected in series to form a battery pack, with the support side facing bottom during testing, while maintaining all other testing conditions. The battery pack was mounted on a vibration table according to GB / T2423.43. The testing process was conducted according to GB / T2423.56. Random and fixed-frequency vibration loads were applied in each direction, preferably in the following order: random z-axis, fixed-frequency z-axis, random y-axis, fixed-frequency y-axis, random x-axis, fixed-frequency x-axis (the line connecting the front and rear of the battery pack is the x-axis direction, and the horizontal direction perpendicular to the x-axis is the y-axis direction). The vibration frequency, power spectral density (PSD), and vibration time are shown in the table below.

[0110]

[0111] After vibration, the battery pack was placed at room temperature (20°C) until thermal equilibrium was reached. The battery pack was then charged at a constant current of 0.33C to the upper limit voltage at room temperature, and then charged at a constant voltage of 0.33C until the current dropped to 0.05C. After standing for 30 minutes, the battery pack was discharged at a constant current of 0.33C to the lower limit voltage. The above steps were repeated for a total of 3 charge-discharge cycles. The discharge capacity Q1 of the third charge-discharge cycle was obtained and taken as the fixed capacity.

[0112] Charge the battery pack to the upper limit voltage using a constant current of 0.33C, then charge it again using a constant voltage of 0.33C until the current drops to 0.05C. After resting for 30 minutes, discharge the battery pack to the lower limit voltage using a constant current of 0.33C. This constitutes one cycle. After n cycles, record the battery pack discharge capacity Qn of the nth cycle. The formula for calculating the battery pack capacity retention rate is "Battery pack capacity retention rate = Qn / Q1 × 100%". Record the number of cycles n when the capacity retention rate first falls below 80% as the cycle number of the battery pack. If n is less than 1200, it is unqualified; if n is greater than or equal to 1200 and less than 1400, it is qualified; and if n is greater than or equal to 1400, it is good.

[0113] When the positive electrode active material of a pouch battery is a nickel-cobalt-manganese ternary cathode, the upper limit voltage of the battery pack is 4.25V×12=51V, and the lower limit voltage is 2.5V×12=30V; when the positive electrode active material of a pouch battery is lithium iron phosphate, the upper limit voltage of the battery pack is 3.6V×12=43.2V, and the lower limit voltage is 2.5V×12=30V.

[0114] In this test, the active material for the positive electrode of the pouch battery was selected from a nickel-cobalt-manganese ternary LiNi alloy. 0.6 Co 0.2 Mn 0.2 Taking O2 as an example, 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.

[0115] Regarding the test results, referring to Table 1 above, the explanation is as follows:

[0116] As can be seen from Examples 1-10, when the formula value of dh satisfies the range of 0mm≤dmm-hmm≤9.7mm, the battery pack capacity retention rate test results are all good or qualified, with no unqualified results, thus meeting the performance requirements.

[0117] In Comparative Examples 1 and 2, the formula value of dh was lower than the lower limit. The battery pack capacity retention rate test result was unqualified and could not meet the performance requirements.

[0118] In some embodiments, the dimension of the support member 2 along a third direction is greater than the dimension of the recessed region 123 along a third direction.

[0119] The dimension of the support member 2 along the third direction is larger than the dimension of the recessed area 123 along the third direction, so that the support member 2 can completely cover the recessed area 123 and form effective support, thereby improving the overall structural strength and assembly stability of the battery pack, ensuring the flatness of the battery pack end face, and ensuring the assembly efficiency of the battery pack. At the same time, it helps to disperse the contact pressure between the support member 2 and the first end face 1201 during the assembly process, avoiding local deformation or damage.

[0120] In some embodiments, the support member 2 at least partially overlaps with the first protrusion 1221 along a first direction.

[0121] The support member 2 extends at least partially beyond the end of the recessed area 123 in the third direction, so that the support member 2 and the first protrusion 1221 overlap at least partially in the first direction. The support member 2 forms a shield for the first protrusion 1221, reducing the risk of stress concentration in the first protrusion 1221 when subjected to external impact, and improving the overall structural reliability of the battery pack.

[0122] In some embodiments, the elastic modulus of the support member 2 ranges from 60 GPa to 200 GPa.

[0123] The elastic modulus can be regarded as an indicator of how easily a material undergoes elastic deformation. The larger the value, the greater the stiffness of the material and the smaller the elastic deformation under a certain stress.

[0124] By limiting the lower limit of the elastic modulus of the support member 2, it is ensured that the support member 2 has sufficient structural rigidity to avoid excessive deformation during assembly or use, thereby effectively maintaining the support effect on the recessed area 123; by limiting the upper limit of the elastic modulus, it is prevented that the support member 2 is too hard and causes stress concentration, reducing the risk of damage to the surface of the soft pack battery and improving the safety and service life of the battery pack.

[0125] For example, in this embodiment, the elastic modulus of the support member 2 can be 60GPa, 80GPa, 100GPa, 120GPa, 140GPa, 160GPa, 180GPa, 190GPa, or 200GPa, or it can be a range formed by any two of the above values.

[0126] In some embodiments, combined with Figure 3 As shown, along the third direction, the support member 2 and the first protrusion 1221 are spaced apart by a distance of emm, which satisfies the condition: 10mm≤emm≤150mm.

[0127] In this embodiment, the support member 2 does not overlap with the first protrusion 1221. The support member 2 is only disposed in the recessed area 123 to ensure independent support for the recessed area 123 and avoid structural interference with the first protrusion 1221.

[0128] If the distance e between the support member 2 and the first protrusion 1221 is too large, it may weaken the support effect of the support member 2 on the recessed area 123, affecting the overall structural stability; if the distance e between the support member 2 and the first protrusion 1221 is too small, there is a risk of interference with the first protrusion 1221, which is not conducive to the control of assembly accuracy.

[0129] For example, in this embodiment, the value of emm can be 10mm or 20mm or 35mm or 50mm or 70mm or 90mm or 110mm or 130mm or 150mm, or it can be a range formed by any two of the above values.

[0130] In some embodiments, at least two support members 2 are provided along a third direction.

[0131] At least two support members 2 are provided along a third direction, that is, at least two support members 2 are spaced apart along the length of the battery pack, to enhance the uniformity of support for the recessed area 123 and prevent local stress concentration. The multiple support members 2 work together along the length direction to effectively distribute external loads and improve the overall stiffness and deformation resistance of the structure.

[0132] In this embodiment, the support member 2 can specifically be a metal fastening band used to constrain multiple pouch batteries 1 along the stacking direction of the pouch batteries 1. For a detailed explanation of the metal fastening band, please refer to the above. By having at least two metal fastening bands spaced apart along the length of the battery pack, the constraint force can be distributed more evenly, resulting in a better constraint effect. This effectively suppresses uneven expansion of the battery pack at different locations and avoids structural failure caused by localized stress concentration. Simultaneously, the multi-point distribution of the metal fastening bands can improve overall stiffness and enhance resistance to vibration and impact.

[0133] In some embodiments, the hardness of the support member 2 is greater than the hardness of the shell 12.

[0134] By making the hardness of the support member 2 greater than that of the shell 12, plastic deformation of the support member 2 under stress can be effectively avoided, thereby maintaining its stable support for the recessed area 123. At the same time, the difference in hardness helps to guide the reasonable distribution of stress during assembly.

[0135] In some embodiments, combined with Figure 3 As shown, along the third direction, the width of support member 2 is fmm, which satisfies: 10mm≤fmm≤60mm.

[0136] By limiting the upper limit of the width f of the support member 2 along the third direction, it can be ensured that the support member 2 provides sufficient support area while avoiding material waste due to excessive width, and also avoid affecting heat dissipation efficiency. At the same time, by limiting the lower limit of the width f of the support member 2 along the third direction, it is possible to prevent the support member 2 from squeezing the shell 12 of the soft-pack battery 1, which would lead to local stress concentration, and then squeezing the battery cell and causing the electrode to fall off, posing a safety risk. Furthermore, if the width f of the support member 2 is too small, it will result in insufficient constraint force on the battery pack, affecting the overall structural stability.

[0137] For example, in this embodiment, the value of fmm can be 10mm or 15mm or 20mm or 25mm or 30mm or 35mm or 40mm or 45mm or 50mm or 55mm or 60mm, or it can be a range formed by any two of the above values.

[0138] In some embodiments, the projected area of ​​the support member 2 on the first end face 1201 along the first direction is 40 mm. 2 -1860mm 2 .

[0139] When the projected area of ​​the support member 2 on the first end face 1201 along the first direction is too small, the support member 2 will not cover the first end face 1201 sufficiently, which may result in insufficient local support and affect the overall structural stability. When the projected area is too large, it may cause material waste and increase the internal space occupied by the battery pack, which is not conducive to improving energy density.

[0140] For example, in this embodiment, the value of the projected area of ​​the support member 2 on the first end face 1201 along the first direction can be 40mm² or 100mm² or 200mm² or 400mm² or 600mm² or 800mm² or 1000mm² or 1200mm² or 1500mm² or 1800mm² or 1860mm², or it can be a range formed by any two of the above values.

[0141] In some embodiments, the housing 12 has a second end face 1202 on the side opposite to the first end face 1201 along the first direction, and the sealing edge 122 protrudes from the second end face 1202 along the first direction and also forms a second protrusion.

[0142] A second protrusion is also formed on the side of the edge sealing 122 away from the first end face 1201 along the first direction. The second protrusion is formed for the same reason as the first protrusion 1221, which is naturally formed by the stacking of materials during the edge sealing folding process. The second protrusion and the first protrusion 1221 are symmetrically distributed along the first direction.

[0143] In some embodiments, the height of the second protrusion along the first direction is greater than that of the first protrusion 1221.

[0144] The height of the second protrusion along the first direction is greater than that of the first protrusion 1221, so as to enhance the structural support of the second end face 1202 and improve the sealing effect of the second end face 1202.

[0145] In some embodiments, combined with Figure 5 As shown, a transition portion 124 is also formed at the connection between the first protrusion 1221 and the shell body 121.

[0146] By forming a transition portion 124 at the connection between the first protrusion 1221 and the shell body 121, the stress concentration phenomenon at the connection can be effectively alleviated, and the structural durability can be improved.

[0147] In some embodiments, the transition portion 124 is an arc transition, and the radius of its R-angle ranges from 0.3 to 5.

[0148] Alternatively, the transition section 124 may have a chamfered transition, with the chamfer angle ranging from 100° to 150°.

[0149] The radius (R) angle can be adjusted by controlling factors such as the casing thickness, cell thickness, and the distance between the sealing edge and the cell.

[0150] In addition, the range of the protrusion height hmm of the first protrusion 1221 along the first direction is also controlled by adjusting the shell thickness, the cell thickness, and the spacing between the sealing edge and the cell.

[0151] The transition section 124 can be arc-shaped or inclined, and its radius of curvature or tilt angle is set according to the material properties and folding process parameters to ensure that the edge banding 122 does not crack or break during the bending process.

[0152] When the transition part 124 is a circular arc transition, by limiting the range of its R-angle radius, it is easier to control the degree of material deformation during the molding process, facilitate edge sealing, and reduce processing difficulty; at the same time, reasonably limiting the R-angle radius can effectively avoid material fatigue failure caused by stress concentration, and avoid stress concentration caused by too small R-angle or waste of space caused by too large R-angle.

[0153] Similarly, when the transition section 124 is chamfered, by setting a reasonable chamfer angle and width range, both structural strength and processing difficulty can be guaranteed.

[0154] For example, in this embodiment, the value of the R-angle radius can be 0.3 or 0.5 or 0.8 or 1.2 or 1.7 or 2.3 or 3.0 or 3.8 or 4.5 or 5, or it can be a range formed by any two of the above values.

[0155] For example, in this embodiment, the chamfer angle can be 100° or 105° or 110° or 115° or 120° or 125° or 130° or 135° or 140° or 145° or 150°, or it can be a range formed by any two of the above values.

[0156] In some embodiments, combined with Figure 3 As shown, the width of the first protrusion 1221 along the third direction is gmm, which satisfies: 5mm≤gmm≤30mm.

[0157] The width of the first protrusion 1221 along the third direction reflects the width of the sealing edge 122 along the third direction. The width of the sealing edge 122 along the third direction has a certain impact on the sealing edge forming accuracy and connection reliability. If the width is too small, the sealing edge structure will not be strong enough, affecting the sealing performance; if the width is too large, it may cause material waste and assembly interference.

[0158] Similarly, by limiting the lower limit of the width g of the first protrusion 1221 along the third direction, it can be ensured that the sealing structure has sufficient strength and sealing contact area, avoiding the risk of loose connection or leakage due to insufficient width; by limiting the upper limit of the width g of the first protrusion 1221 along the third direction, it can be avoided that material waste and assembly space conflict due to excessive width can be avoided, ensuring that the sealing structure achieves a compact design while meeting the requirements of strength and sealing performance.

[0159] For example, in this embodiment, the value of gmm can be 5mm or 7mm or 10mm or 13mm or 16mm or 19mm or 22mm or 25mm or 27mm or 30mm, or it can be a range formed by any two of the above values.

[0160] In some embodiments, the housing 12 includes a metal layer and an insulating layer, wherein the thickness of the metal layer accounts for less than or equal to 25% of the total thickness of the housing 12.

[0161] The housing 12 includes a metal layer and an insulating layer. By limiting the upper limit of the proportion of the thickness of the metal layer to the total thickness of the housing 12, the overall weight of the housing can be effectively reduced and the cost of using metal materials can be reduced. At the same time, stress concentration caused by excessive metal layer thickness can be avoided, reducing the risk of bending and cracking, thereby facilitating the molding of the housing 12 and making it easier to form the edge seal 122.

[0162] For example, in this embodiment, the percentage of the thickness of the metal layer to the total thickness of the housing 12 can be 15%, 20%, or 25%, or it can be a range formed by any two of the above values.

[0163] In some embodiments, the housing 12 includes a metal layer and an insulating layer, the insulating layer being located on the outer surface of the metal layer facing away from the battery cell.

[0164] The insulating layer is located on the outer surface of the metal layer on the side away from the battery cell. The insulating layer plays the role of electrical insulation and protection against the external environment, effectively preventing the risk of short circuit caused by external conductive objects contacting the metal layer, while improving the corrosion resistance and mechanical protection performance of the casing.

[0165] In some embodiments, the thickness of the insulating layer ranges from 30 μm to 250 μm.

[0166] By limiting the upper limit of the insulation layer thickness, the overall thickness of the casing and material waste caused by excessive insulation layer thickness can be avoided. At the same time, limiting the lower limit of the insulation layer thickness ensures that it has sufficient insulation performance and protection capabilities, and avoids insulation failure or insufficient protection caused by excessive thickness.

[0167] For example, in this embodiment, the thickness of the insulating layer can be 30μm, 50μm, 80μm, 110μm, 140μm, 170μm, 200μm, 230μm, or 250μm, or it can be a range formed by any two of the above values.

[0168] According to an embodiment of the present invention, in another aspect, an electrical device is also provided, comprising:

[0169] The main body of the electrical device, and the battery pack electrically connected to the main body of the electrical device.

[0170] In this embodiment, the electrical device can be an electronic device, an electric vehicle, or an energy storage system. The electronic device includes a smartphone, tablet computer, or laptop computer. The electric vehicle includes a pure electric vehicle, a hybrid electric vehicle, or an electric motorcycle, etc. The energy storage system is used for grid energy storage or home energy management.

[0171] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. 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 all such modifications and variations fall within the scope defined by the present invention.

Claims

1. A battery pack, characterized in that, include: A pouch battery (1) includes a cell and a housing (12) for encapsulating the cell. The housing (12) includes a main body (121) and sealing edges (122) formed on both sides of the main body (121) along a third direction. The sealing edges (122) protrude from a first end face (1201) of the main body (121) along a first direction to form a first protrusion (1221). The first direction is perpendicular to the first end face (1201). The first end face (1201) and the first protrusions (1221) located at both ends of the first end face (1201) along the third direction together define a recessed region (123). The support member (2) is at least partially disposed within the recessed area (123); The third direction is perpendicular to the first direction; The thickness of the portion of the support member (2) that overlaps with the recessed area (123) along the first direction is greater than the protrusion height of the first protrusion (1221) along the first direction; Along the third direction, the support member (2) is spaced apart from the first protrusion (1221); The thickness of the portion of the support member (2) that overlaps with the recessed area (123) along the first direction is d mm, and the protrusion height of the first protrusion (1221) along the first direction is h mm, satisfying: 0.5 mm ≤ d mm - h mm ≤ 9.7 mm; where the value of d is in the range of 1.2 mm ≤ d mm ≤ 10 mm. The support member (2) is made of metal; the elastic modulus of the support member (2) is in the range of 60GPa-200GPa; the shell (12) includes a metal layer and an insulating layer, and the thickness of the metal layer accounts for less than or equal to 25% of the total thickness of the shell (12); Along the third direction, the support member (2) and the first protrusion (1221) are spaced apart by a distance of emm, satisfying: 10mm≤emm≤150mm; The hardness of the support member (2) is greater than that of the shell (12).

2. The battery pack according to claim 1, characterized in that, The support member (2) is provided in at least two along the third direction.

3. The battery pack according to claim 1, characterized in that, Along the third direction, the width of the support member (2) is fmm, which satisfies: 10mm≤fmm≤60mm.

4. The battery pack according to any one of claims 1 to 3, characterized in that, The projected area of ​​the support member (2) on the first end face (1201) along the first direction is 40 mm. 2 -1860mm 2 .

5. The battery pack according to any one of claims 1 to 3, characterized in that, The housing (12) has a second end face (1202) on the side opposite to the first end face (1201) along the first direction, and the sealing edge (122) protrudes from the second end face (1202) along the first direction and also forms a second protrusion.

6. The battery pack according to claim 5, characterized in that, The height of the second protrusion along the first direction is greater than that of the first protrusion (1221).

7. The battery pack according to any one of claims 1 to 3, characterized in that, A transition portion (124) is also formed at the connection between the first protrusion (1221) and the shell body (121).

8. The battery pack according to claim 7, characterized in that, The transition section (124) has a circular arc transition, and the radius of its R-angle ranges from 0.3 to 5. Alternatively, the transition portion (124) may be chamfered, with the chamfer angle ranging from 100° to 150°.

9. The battery pack according to any one of claims 1 to 3, characterized in that, The width of the first protrusion (1221) along the third direction is gmm, which satisfies: 5mm≤gmm≤30mm.

10. The battery pack according to any one of claims 1 to 3, characterized in that, The insulating layer is located on the outer surface of the metal layer on the side opposite to the battery cell.

11. The battery pack according to claim 10, characterized in that, The thickness of the insulating layer ranges from 30μm to 250μm.

12. An electrical appliance, characterized in that, include: The electrical device body and the battery pack as described in any one of claims 1 to 11, which is electrically connected to the electrical device body.

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