Battery cell, battery, and electrical device

Abstract

A battery cell (6), a battery (2), and an electrical device. The battery cell (6) comprises an electrode assembly (10), a casing (20), a pressure relief mechanism (40), and a protective member (50). The electrode assembly (10) is accommodated in the casing (20). The casing (20) comprises a wall portion. The pressure relief mechanism (40) is arranged on the wall portion. In the thickness direction of the wall portion, at least part of the protective member (50) is provided between the pressure relief mechanism (40) and the electrode assembly (10). When a high-temperature substance outside the battery cell (6) acts on the pressure relief mechanism (40) and melts through the pressure relief mechanism (40), the protective member (50) can bear the thermal shock of the high-temperature substance and separate at least part of the high-temperature substance from the electrode assembly (10), so that the risk of conduction of a positive electrode and a negative electrode of the electrode assembly (10) by the high-temperature substance is reduced, thereby improving the reliability of the battery cell (6).

Description

Battery cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202420281933.1, filed on February 5, 2024, entitled “Battery Cell, Battery, and Electrical Device,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0004] With the advancement of battery technology, battery cells are being used in a growing number of fields and are gradually replacing traditional fossil fuels in the automotive powertrain sector. Battery cells store chemical energy and controllably convert it into electrical energy. In recyclable battery cells, after discharge, the active material can be activated by recharging for continued use.

[0005] How to improve the reliability of battery cells is an important research direction in the industry.

[0006] Summary of the Invention

[0007] The present application provides a battery cell, a battery, and an electrical device, which can improve reliability.

[0008] In a first aspect, the present application provides a battery cell comprising an electrode assembly, a housing, a pressure relief mechanism, and a protective member. The electrode assembly is housed within the housing. The housing includes a wall portion. The pressure relief mechanism is disposed in the wall portion. At least a portion of the protective member is disposed between the pressure relief mechanism and the electrode assembly in the thickness direction of the wall portion.

[0009] In the event of thermal runaway in a battery cell, the internal pressure of the battery cell can be transmitted to the pressure relief mechanism through the protective component, causing it to activate promptly. This activation releases the contents of the housing, reducing the risk of explosion or fire in the battery cell and improving its reliability. If high-temperature material outside the battery cell acts on and melts through the pressure relief mechanism, the protective component can withstand the thermal shock of the high-temperature material and isolate at least part of it from the electrode assembly, reducing the risk of the high-temperature material conducting electricity between the positive and negative electrodes of the electrode assembly and improving the reliability of the battery cell.

[0010] In one or more optional embodiments above, the pressure relief mechanism includes a weak portion and a pressure relief portion surrounded by the weak portion. In the thickness direction, the projection of the pressure relief portion is located within the projection of the protection member, and the projection of the weak portion is located within the projection of the protection member.

[0011] The protective component can shield the weak portion and the pressure relief portion from the inside. Even if the weak portion or the pressure relief portion is melted through by a high-temperature substance, the protective component can separate the high-temperature substance from the electrode assembly.

[0012] In one or more of the above optional embodiments, the wall portion is provided with a pressure relief hole, which extends through the wall portion along the thickness direction. The pressure relief mechanism is connected to the wall portion and covers the pressure relief hole. The projection of the pressure relief hole in the thickness direction is located within the projection of the protective member. The protective member can shield the pressure relief hole from the inside, isolating high-temperature substances that pass through the pressure relief hole from the electrode assembly to a certain extent, thereby reducing the risk of short circuits and improving the reliability of the battery cell.

[0013] In one or more of the above optional embodiments, in the thickness direction, the projection of the pressure relief mechanism is located within the projection of the protection component, thereby reducing the risk of short circuit and improving the reliability of the battery cell.

[0014] In one or more optional embodiments above, the protective member includes a first region and a second region surrounding the first region, the first region completely overlaps with the pressure relief mechanism in a thickness direction, and the width W of the second region is 0.5 mm to 10 mm.

[0015] Limiting W to greater than or equal to 0.5 mm reduces the risk of the protective member not fully covering the pressure relief mechanism due to assembly errors. Limiting W to less than or equal to 10 mm reduces the resistance of the protective member to escape from the housing when the pressure relief mechanism is activated, reduces the protective member's obstruction of internal substances, and improves pressure relief efficiency.

[0016] In one or more of the above optional embodiments, the thickness of the protective member is greater than the thickness of the pressure relief mechanism, so as to reduce the risk of the protective member being melted through by high-temperature substances and improve the reliability of the battery cell.

[0017] In one or more optional embodiments above, the thickness of the protective member is 0.4 mm-2 mm; optionally, the thickness of the protective member is 0.5 mm-1.5 mm.

[0018] The thickness of the protective member is limited to greater than or equal to 0.4mm to reduce the risk of the protective member being melted through by high-temperature substances and improve the reliability of the battery cell. The thickness of the protective member is limited to less than or equal to 2mm to reduce the difficulty of the protective member deforming when the pressure relief mechanism is activated, thereby allowing the protective member to be removed from the housing in a timely manner, reducing the protective member's obstruction to internal substances and improving pressure relief efficiency.

[0019] In one or more optional embodiments above, the melting point of the protection member is greater than or equal to 250°C. Optionally, the melting point of the protection member is greater than or equal to 300°C.

[0020] The melting point of the protective component is greater than or equal to 250°C, and it can withstand high thermal shock. When the high-temperature material melts through the pressure relief mechanism and contacts the protective component, the protective component can withstand the thermal shock of the high-temperature material and is not prone to deformation, melting through and other problems under the action of high temperature, thereby separating at least part of the high-temperature material from the electrode assembly and reducing the risk of short circuit.

[0021] In one or more optional embodiments above, the elastic modulus of the protection member is less than or equal to 4500 MPa. Optionally, the elastic modulus of the protection member is less than or equal to 4000 MPa.

[0022] The protective member has a low elastic modulus. If a battery cell experiences thermal runaway, the protective member can adhere tightly to the pressure relief mechanism under the internal pressure of the battery cell, thereby transmitting the internal pressure of the battery cell to the pressure relief mechanism and causing it to activate in a timely manner. When the pressure relief mechanism is activated, the protective member can also deform and escape from the housing, thereby reducing the protective member's barrier to internal substances and improving pressure relief efficiency.

[0023] In one or more optional embodiments above, the material of the protective component is polyimide or polyethylene terephthalate, which have a relatively high melting point and are not easily melted through, and are not easily corroded by electrolytes.

[0024] In one or more optional embodiments above, the battery cell further includes an insulating member, which is disposed between the wall portion and the electrode assembly, and is connected to the wall portion and abuts against the electrode assembly.

[0025] The insulating member separates the electrode assembly from the wall, reducing the risk of the wall connecting the positive and negative electrodes of the electrode assembly, thereby improving the reliability of the battery cell. If the battery cell is subjected to external impact, the insulating member can limit the shaking of the electrode assembly within the casing, thereby reducing the risk of failure in the connection between the electrode assembly and other components and improving the reliability of the battery cell.

[0026] In one or more optional embodiments above, the protective member is disposed between the insulating member and the pressure relief mechanism in the thickness direction, and the insulating member can provide support for the protective member.

[0027] In one or more of the above optional embodiments, the protective member is connected to the insulating member. The insulating member can limit the protective member, reduce the risk of the protective member shifting within the housing, and enable the protective member to cover the pressure relief mechanism from the inside to shield the high-temperature material from melting through the pressure relief mechanism.

[0028] In one or more of the above optional embodiments, a recess is provided on the side of the insulating member facing the wall. The protective member is at least partially accommodated in the recess. The provision of the recess allows the insulating member and the protective member to share space in the thickness direction, thereby improving space utilization. During assembly of the insulating member and the protective member, the recess helps position the protective member, thereby simplifying the assembly process.

[0029] In one or more optional embodiments above, the protective member is entirely accommodated in the recess. In the thickness direction, the protective member does not protrude from the surface of the insulating member facing the wall, thereby reducing the risk of the protective member interfering with the fit between the insulating member and the wall.

[0030] In one or more of the above optional embodiments, the side wall of the recess has a step surface, and the protective member abuts against and is connected to the step surface.

[0031] The stepped surface supports the protective member and separates the bottom wall of the recess from the protective member, thereby forming an insulating cavity between the bottom wall and the protective member. This insulating cavity reduces heat transfer to the bottom wall of the recess, thereby reducing heat conduction to the electrode assembly and reducing the risk of electrode assembly short circuits. The stepped surface reduces the connection area between the protective member and the insulating member, making it easier to separate the protective member from the insulating member in the event of thermal runaway of the battery cell.

[0032] In one or more of the above optional embodiments, the insulating component is provided with a through hole, and the through hole is located on a side of the protective component away from the pressure relief mechanism.

[0033] The through-hole connects to the space between the insulating member and the electrode assembly. In the event of thermal runaway of a battery cell, substances generated by the electrode assembly can act on the protective member through the through-hole, which in turn applies pressure to the pressure relief mechanism, causing it to activate promptly and forming a pressure relief channel. Substances generated by the electrode assembly can be quickly discharged to the exterior of the battery cell through the through-hole and the pressure relief channel.

[0034] In one or more of the above optional embodiments, the melting point of the protective member is higher than that of the insulating member. The protective member has a higher melting point. If a high-temperature substance melts through the pressure relief mechanism, the protective member can withstand the thermal shock of the high-temperature substance and is not easily melted through, thereby isolating at least a portion of the high-temperature substance from the electrode assembly and reducing the risk of a short circuit.

[0035] In one or more of the above optional embodiments, the specific heat capacity of the insulating member is greater than or equal to 1600 J / (kg×°C); optionally, the specific heat capacity of the insulating member is greater than or equal to 2000 J / (kg×°C). The insulating member has a high specific heat capacity and can absorb a high amount of heat. When an external high-temperature substance melts through the pressure relief mechanism and adheres to the protective member, the insulating member can absorb the heat of the high-temperature substance through the protective member, thereby reducing the temperature rise of the protective member, reducing the risk of the protective member being melted through, and improving the reliability of the battery cell.

[0036] In one or more of the above optional embodiments, the insulating member includes an insulating substrate and a coating disposed on a surface of the insulating substrate, wherein the specific heat capacity of the coating is greater than the specific heat capacity of the insulating substrate. In the thickness direction, the projection of the coating at least partially overlaps with the projection of the pressure relief mechanism. The coating and the protective member can function as a double layer of protection. If the pressure relief mechanism is melted through by an external high-temperature material, even if the high-temperature material falls onto the coating, the coating can quickly absorb heat. Due to the high specific heat capacity of the coating, the coating has a low temperature rise and is less susceptible to melt-through.

[0037] In one or more of the above optional embodiments, the protective member is connected to the coating. When external high-temperature materials fall onto the protective member, the coating can absorb the heat of the protective member, reduce the temperature rise of the protective member, and reduce the risk of the protective member being melted through.

[0038] In one or more of the above optional embodiments, the melting point of the coating is higher than that of the insulating substrate. The coating has a higher melting point and is not easily melted through, thereby isolating high-temperature substances from the electrode assembly and improving reliability.

[0039] In a second aspect, the present application provides a battery comprising a plurality of battery cells provided according to any embodiment of the first aspect.

[0040] In a third aspect, the present application provides an electrical device, comprising a battery provided according to any embodiment of the second aspect, wherein the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0042] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0043] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application;

[0044] FIG3 is a schematic diagram of an explosion of a battery cell provided in some embodiments of the present application;

[0045] FIG4 is a schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0046] FIG5 is a schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0047] FIG6 is an enlarged schematic diagram of the circle frame in FIG5;

[0048] FIG7 is an enlarged schematic diagram of the circle frame of FIG6;

[0049] FIG8 is a schematic structural diagram of a protective component of a battery cell provided in some embodiments of the present application;

[0050] FIG9 is a partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application;

[0051] FIG10 is a schematic partial cross-sectional view of a battery cell provided in some other embodiments of the present application.

[0052] In the accompanying drawings, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0053] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0054] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0055] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments.

[0056] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0057] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0058] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components in different embodiments are omitted. It should be understood that the thickness, length, width, and other dimensions of the various components in the embodiments of this application, as well as the overall thickness, length, width, and other dimensions of the integrated device shown in the drawings are merely illustrative and should not constitute any limitation on this application.

[0059] The term "plurality" used in this application refers to two or more (including two).

[0060] In the embodiment of the present application, the battery cell may be a secondary battery cell. A secondary battery cell refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0061] The battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a sodium-lithium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium-sulfur battery cell, a magnesium-ion battery cell, a nickel-hydrogen battery cell, a nickel-cadmium battery cell, a lead-acid battery cell, etc., and the embodiments of the present application are not limited to this.

[0062] A battery cell generally includes an electrode assembly, which includes a positive electrode and a negative electrode.

[0063] During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed between the positive and negative electrodes. A separator is placed between the positive and negative electrodes to prevent a short circuit between the positive and negative electrodes while allowing the active ions to pass through.

[0064] In some embodiments, the positive electrode may be a positive electrode sheet, which may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0065] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0066] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0067] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include but are not limited to lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2) and at least one of its modified compounds, etc.

[0068] In some embodiments, the positive electrode may be a metal foam or carbon foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or the like. When the metal foam is used as the positive electrode, the surface of the metal foam may or may not be provided with a positive electrode active material. For example, a lithium source material, potassium metal, or sodium metal may be filled and / or deposited within the metal foam, where the lithium source material is lithium metal and / or a lithium-rich material.

[0069] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0070] As an example, the negative electrode current collector can be a metal foil, a metal foam, or a composite current collector. For example, as the metal foil, aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium can be used. The metal foam can be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0071] As an example, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector.

[0072] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0073] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0074] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0075] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0076] In some embodiments, the separator is a separator membrane. The separator membrane of the present application can be any well-known porous separator membrane with good chemical stability and mechanical stability.

[0077] For example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film. In the case of a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component positioned between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0078] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transport ions and isolate the positive and negative electrodes.

[0079] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte can be selected based on the application's needs. The electrolyte can be liquid, gel, or solid.

[0080] The liquid electrolyte includes an electrolyte salt and a solvent.

[0081] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0082] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be an ether solvent. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0083] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0084] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0085] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, or the like.

[0086] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON film), a sulfide solid electrolyte (crystalline lithium superion conductor (lithium germanium phosphosulfide, silver germanium sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0087] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0088] In some embodiments, the electrode assembly is a wound structure, wherein the positive electrode sheet and the negative electrode sheet are wound into the wound structure.

[0089] In some embodiments, the electrode assembly is a laminate structure.

[0090] As an example, multiple positive electrode sheets and multiple negative electrode sheets can be provided respectively, and the multiple positive electrode sheets and the multiple negative electrode sheets can be alternately stacked.

[0091] As an example, a plurality of positive electrode sheets may be provided, and the negative electrode sheet may be folded to form a plurality of stacked folded segments, with a positive electrode sheet being sandwiched between adjacent folded segments.

[0092] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0093] As an example, a plurality of separators may be provided, each of which is disposed between any adjacent positive electrode sheets or negative electrode sheets.

[0094] As an example, the separator may be provided continuously, and may be provided between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0095] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0096] In some embodiments, the electrode assembly is provided with tabs that can conduct current from the electrode assembly. The tabs include a positive tab and a negative tab.

[0097] In some embodiments, a battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (e.g., polypropylene), a composite metal housing (e.g., a copper-aluminum composite housing), or an aluminum-plastic film.

[0098] As an example, the battery cells may be cylindrical, prismatic, soft-pack or other shaped battery cells. Prismatic battery cells include square-shell, blade-shaped, and polygonal battery cells. Polygonal battery cells may be, for example, hexagonal.

[0099] The battery mentioned in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0100] In some embodiments, the battery may be a battery module. When there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0101] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are housed in the case.

[0102] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0103] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0104] The development of battery technology must take into account multiple design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0105] The pressure relief mechanism on a battery cell has a significant impact on its reliability. For example, short circuits and overcharging can cause thermal runaway within the cell, leading to a sudden increase in pressure. In this situation, the pressure relief mechanism activates to release internal pressure, reducing the risk of explosion or fire.

[0106] A pressure relief mechanism is a component or element that activates to release internal gas when the internal pressure or temperature of a battery cell reaches a predetermined threshold. This threshold varies depending on the design requirements. It may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0107] The pressure relief mechanism may take the form of an explosion-proof valve, an air valve, a pressure relief valve, or a safety valve, and may specifically employ a pressure-sensitive element or structure. Specifically, when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism actuates, or a weak area within the pressure relief mechanism ruptures, thereby forming an opening or passage through which the internal pressure can be released. Alternatively, the pressure relief mechanism may employ a temperature-sensitive element or structure. Specifically, when the internal temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism actuates, thereby forming an opening or passage through which the internal pressure can be released.

[0108] The "activation" mentioned in this application refers to the action of the pressure relief mechanism or its activation to a certain state, thereby allowing the internal pressure of the battery cell to be released. The action produced by the pressure relief mechanism may include, but is not limited to: at least a portion of the pressure relief mechanism is ruptured, broken, torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged outward from the actuated part as emissions. In this way, the pressure of the battery cell can be relieved under controllable pressure, thereby avoiding potential more serious accidents.

[0109] The emissions from the battery cells mentioned in this application include but are not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0110] Batteries typically contain multiple cells. When a cell experiences thermal runaway, the high-temperature substances (such as hot gases and particles) inside the cell are released after the pressure relief mechanism is activated. The released hot gases and particles rebound and impact adjacent, healthy cells, damaging their pressure relief mechanisms. In severe cases, the pressure relief mechanisms of healthy cells can melt through, allowing the hot particles to enter the healthy cells, causing them to short-circuit and thermal runaway, leading to heat spread and impacting battery reliability.

[0111] In view of this, an embodiment of the present application provides a technical solution, which provides a protective component on the inner side of the pressure relief mechanism to separate the high-temperature material from the electrode assembly when the external high-temperature material melts through the pressure relief mechanism, thereby reducing the risk of short circuit of the electrode assembly and improving the reliability of the battery cell.

[0112] The battery cells described in the embodiments of the present application are suitable for use in batteries and electrical devices using the batteries.

[0113] The battery cells, batteries, and electrical devices disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. The electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, battery-powered vehicles, electric vehicles, ships, spacecraft, and the like. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0114] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0115] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0116] As shown in FIG1 , a battery 2 is provided inside the vehicle 1. The battery 2 may be provided at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1. For example, the battery 2 may serve as an operating power source for the vehicle 1.

[0117] The vehicle 1 may further include a controller 3 and a motor 4 . The controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of the vehicle 1 during startup, navigation, and driving.

[0118] In some embodiments of the present application, the battery 2 can not only serve as the operating power source of the vehicle 1, but also serve as the driving power source of the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0119] FIG2 is an exploded view of a battery according to some embodiments of the present application. As shown in FIG2 , the battery 2 includes a housing 5 and a battery cell 6 , wherein the battery cell 6 is accommodated in the housing 5 .

[0120] The housing 5 is used to accommodate the battery cells 6 and can have various structures. In some embodiments, the housing 5 can include a first housing portion 5a and a second housing portion 5b. The first housing portion 5a and the second housing portion 5b overlap each other and together define a storage space 5c for accommodating the battery cells 6. The second housing portion 5b can be a hollow structure with one end open. The first housing portion 5a is a plate-like structure, and the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. The first housing portion 5a and the second housing portion 5b can also both be hollow structures with one end open. The open side of the first housing portion 5a overlaps the open side of the second housing portion 5b to form the housing 5 with the storage space 5c. Of course, the first housing portion 5a and the second housing portion 5b can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0121] In order to improve the sealing performance after the first box body 5a and the second box body 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body 5a and the second box body 5b.

[0122] Assuming that the first box body portion 5a covers the top of the second box body portion 5b, the first box body portion 5a can also be called an upper box cover, and the second box body portion 5b can also be called a lower box body.

[0123] In the battery 2, there can be one or more battery cells 6. If there are multiple battery cells 6, the multiple battery cells 6 can be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections within the multiple battery cells 6. The multiple battery cells 6 can be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 6 can be housed within the housing 5. Alternatively, multiple battery cells 6 can be first connected in series, in parallel, or in a hybrid connection to form a battery module, and then the multiple battery modules can be connected in series, in parallel, or in a hybrid connection to form a single unit and housed within the housing 5.

[0124] Figure 3 is an exploded schematic diagram of a battery cell according to some embodiments of the present application; Figure 4 is a schematic diagram of a portion of the structure of a battery cell according to some embodiments of the present application; Figure 5 is a schematic cross-sectional diagram of a battery cell according to some embodiments of the present application; Figure 6 is an enlarged schematic diagram of the circled portion of Figure 5; Figure 7 is an enlarged schematic diagram of the circled portion of Figure 6; and Figure 8 is a schematic diagram of the structure of a protective member for a battery cell according to some embodiments of the present application. It should be noted that the dashed line in Figure 8 is intended to indicate the boundary between the first and second regions of the protective member; the dashed line shown in Figure 8 does not exist in an actual protective member.

[0125] 3 to 8 , an embodiment of the present application provides a battery cell 6 , which includes an electrode assembly 10 and a housing 20 , wherein the electrode assembly 10 is accommodated in the housing 20 .

[0126] The housing 20 is a hollow structure, forming a space within which the electrode assembly 10 and the electrolyte are housed. The shape of the housing 20 can be determined based on the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a rectangular parallelepiped structure, a rectangular housing can be used; if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be used.

[0127] As an example, the housing 20 includes a shell 21 and an end cover 22 . The shell 21 has an opening, and the end cover 22 is used to cover the opening.

[0128] The shell 21 cooperates with the end cover 22 to form an internal cavity of the battery cell 6 . The formed internal cavity can be used to accommodate the electrode assembly 10 , electrolyte, and other components.

[0129] The housing 21 and the end cap 22 may be separate components. For example, an opening may be provided on the housing 21 , and the end cap 22 may be placed over the opening to form an internal cavity of the battery cell 6 .

[0130] The housing 21 can have various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the housing 21 can be determined according to the specific shape and size of the electrode assembly 10. The housing 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0131] The shape of the end cap 22 can be adapted to the shape of the housing 21 to fit the housing 21. The material of the end cap 22 can be the same as or different from the material of the housing 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (e.g., copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.). In this way, the end cap 22 is less likely to deform when subjected to compression or collision, thereby providing the battery cell 6 with higher structural strength and improved reliability.

[0132] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0133] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be open at one end, with one end cap 22 provided to cover the housing 21. In other examples, the housing 21 may be open at both ends, with two end caps 22 provided to cover the two openings of the housing 21, respectively.

[0134] For example, when the battery cell 6 is used upright, the end cap 22 is located above the electrode assembly 10 along the direction of gravity. When the battery cell 6 is used upside down, the end cap 22 is located below the electrode assembly 10 along the direction of gravity.

[0135] The electrode assembly 10 is a component where electrochemical reactions occur in the battery cell 6. One or more electrode assemblies 10 may be contained in the housing 21.

[0136] As an example, the electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. The portions of the positive and negative electrode sheets containing active material constitute the main body of the electrode assembly 10, while the portions of the positive and negative electrode sheets not containing active material each constitute a tab 11. The tabs 11 may include a positive tab and a negative tab. The positive and negative tabs may be located at the same end of the main body or at opposite ends of the main body.

[0137] In some embodiments, the end cap 22 is provided with an injection hole 222. After the end cap 22 is assembled with the housing 21, electrolyte can be injected into the housing 21 through the injection hole 222. In some embodiments, the battery cell further includes a seal 90 connected to the end cap 22 and used to seal the injection hole 222.

[0138] In some embodiments, the battery cell 6 further includes an electrode terminal 30 disposed on the housing 20 . The electrode terminal 30 can be used to electrically connect to the electrode assembly 10 to output or input electrical energy of the battery cell 6 .

[0139] During the charge and discharge process of the battery, the positive electrode active material and the negative electrode active material react with the electrolyte, and the tabs are connected to the electrode terminals 30 to form a current loop.

[0140] In some embodiments, the battery cell 6 includes two electrode terminals 30 , one electrode terminal 30 is connected to the positive electrode sheet, and the other electrode terminal 30 is connected to the negative electrode sheet.

[0141] In some embodiments, the battery cell 6 further includes a transition piece 80 , which connects the electrode terminal 30 and the tab 11 .

[0142] In some embodiments, the battery cell 6 includes a housing 20 and a pressure relief mechanism 40 . The housing 20 includes a wall portion 20 a , and the pressure relief mechanism 40 is disposed on the wall portion 20 a .

[0143] As an example, the wall portion 20 a may be the end cover 22 or a wall of the housing 21 .

[0144] As an example, the shape of the wall portion 20a may be circular, rectangular, oval, or other shapes.

[0145] In some examples, the pressure relief mechanism 40 and the wall portion 20a may be independently formed components, connected by welding, bonding, or other methods. For example, the wall portion 20a may be provided with a pressure relief hole 221 that extends through the wall portion 20a. The pressure relief mechanism 40 is mounted on the wall portion 20a and covers the pressure relief hole 221, thereby separating the space inside and outside the wall portion 20a. In alternative embodiments, the pressure relief mechanism 40 and the wall portion 20a may also be integrally formed.

[0146] For example, the pressure relief mechanism 40 can be activated when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the substance within the housing 20. The threshold value design varies according to different design requirements. The threshold value may depend on the material of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 6.

[0147] When the internal pressure or temperature of the battery cell 6 reaches a threshold, the pressure relief mechanism 40 is activated to release the gas in the housing 20, thereby relieving the internal pressure of the battery cell 6. As an example, when the pressure relief mechanism 40 is activated, other high-temperature substances, such as particles and debris, can also be released.

[0148] The internal pressure of the battery cell 6 may be the internal pressure of the outer case 20 , and the internal temperature of the battery cell 6 may be the internal temperature of the outer case 20 .

[0149] The actuation of the pressure relief mechanism 40 may be triggered only by the internal pressure of the housing 20 , only by the internal temperature of the housing 20 , or jointly by the internal pressure and the internal temperature of the housing 20 .

[0150] For example, when a battery cell 6 experiences thermal runaway, the accumulation of gas within the housing 20 can cause the internal pressure of the housing 20 to reach or even exceed a threshold pressure. When the internal pressure of the housing 20 reaches the threshold, the pressure relief mechanism 40 activates and forms a pressure relief passage, connecting the interior of the housing 20 with the exterior. Gas within the housing 20 can be discharged through the pressure relief passage, thereby reducing the risk of explosion of the battery cell 6.

[0151] For example, when the electrolyte and active material react and rapidly release heat, the internal temperature of the housing 20 increases, which in turn causes the internal pressure of the housing 20 to increase. When the internal temperature of the housing 20 reaches a threshold, the pressure relief mechanism 40 is activated under the influence of temperature and pressure to form a pressure relief passage, thereby connecting the interior of the housing 20 with the external space. Gas inside the housing 20 can be discharged through the pressure relief passage, thereby reducing the risk of explosion of the battery cell 6.

[0152] In some embodiments, the electrode terminal 30 is mounted on the wall portion 20 a.

[0153] In some embodiments, a battery cell 6 includes an electrode assembly 10, a housing 20, a pressure relief mechanism 40, and a protective member 50. The housing 20 includes a wall portion 20a. The electrode assembly 10 is housed within the housing 20. The pressure relief mechanism 40 is disposed in the wall portion 20a. At least a portion of the protective member 50 is disposed between the pressure relief mechanism 40 and the electrode assembly 10 in the thickness direction Z of the wall portion 20a.

[0154] In the thickness direction Z of the wall portion 20 a , the protective member 50 may completely separate the pressure relief mechanism 40 from the electrode assembly 10 , or may separate only a portion of the pressure relief mechanism 40 from the electrode assembly 10 .

[0155] In the thickness direction Z of the wall portion 20 a , the protection member 50 and the pressure relief mechanism 40 may be spaced apart from each other or may be in contact with each other.

[0156] The protection member 50 may be connected to the wall portion 20a or provided independently of the wall portion 20a. The protection member 50 may be connected to the pressure relief mechanism 40 or provided independently of the pressure relief mechanism 40.

[0157] As an example, when the pressure relief mechanism 40 is actuated, the protective member 50 may rupture, break, open, fly out, or perform other actions under the internal pressure of the battery cell 6 to reduce the barrier provided by the protective member 50 to the contents inside the housing 20 .

[0158] As an example, the protection member 50 is accommodated within the housing 20 .

[0159] When thermal runaway occurs in the battery cell 6, the internal pressure of the battery cell 6 can be transmitted to the pressure relief mechanism 40 through the protective member 50, causing the pressure relief mechanism 40 to be activated in a timely manner; the pressure relief mechanism 40 is activated and releases the material inside the housing 20 to the outside, thereby reducing the risk of explosion or fire of the battery cell 6 and improving the reliability of the battery cell 6. When high-temperature material (such as high-temperature airflow, high-temperature particles, etc.) outside the battery cell 6 acts on the pressure relief mechanism 40 and melts through the pressure relief mechanism 40, the protective member 50 can withstand the thermal shock of the high-temperature material and isolate at least part of the high-temperature material from the electrode assembly 10, reducing the risk of the high-temperature material causing electrical conduction between the positive and negative electrodes of the electrode assembly 10 (for example, the high-temperature material melts through the separator of the electrode assembly 10, causing electrical conduction between the positive and negative electrodes of the electrode assembly 10), thereby improving the reliability of the battery cell 6.

[0160] Compared with the solution of arranging the protective component on the outside of the pressure relief mechanism, arranging the protective component on the inside of the pressure relief mechanism can reduce the risk of the protective component being damaged by external impurities.

[0161] In some embodiments, the pressure relief mechanism 40 includes a weak portion 41. The weak portion 41 is a portion of the pressure relief mechanism 40 having relatively low strength, and is a portion of the pressure relief mechanism 40 that is easily broken, shattered, torn, or opened. Exemplarily, the strength of the pressure relief mechanism 40 is lower than the strength of the portion of the pressure relief mechanism 40 adjacent to the weak portion 41.

[0162] In some examples, grooves, notches, or other structures may be provided in a predetermined region of the pressure relief mechanism 40 to reduce the local strength of the pressure relief mechanism 40, thereby forming a weak portion 41 on the pressure relief mechanism 40. For example, a thinning process may be performed on the predetermined region of the pressure relief mechanism 40, and the thinned portion of the pressure relief mechanism 40 forms the weak portion 41. In other examples, a material treatment may be performed on the predetermined region of the pressure relief mechanism 40 to make the strength of the region weaker than that of other regions. In other words, the weak portion 41 is formed in the predetermined region of the pressure relief mechanism 40.

[0163] The weak portion 41 can rupture when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the substance in the outer shell 20 .

[0164] In some embodiments, the pressure relief mechanism 40 includes a pressure relief portion 42 surrounded by a weakened portion 41 .

[0165] In some examples, the weak portion 41 is annular and surrounds the pressure relief portion 42. In other examples, the ends of the weak portion 41 are not closed, and the line connecting the two ends of the weak portion 41 and the weak portion 41 together define the pressure relief portion 42. For example, the weak portion 41 is U-shaped.

[0166] After at least a portion of the weak portion 41 is ruptured, the pressure relief portion 42 may be turned over or fly out under the action of the internal pressure of the battery cell 6 .

[0167] In some embodiments, in the thickness direction Z, the projection of the weak portion 41 is located within the projection of the protective member 50 .

[0168] The weak portion 41 has low strength and is more easily melted by external high-temperature substances. The protective member 50 can shield the weak portion 41 from the inside. Even if the weak portion 41 is melted by high-temperature substances, the protective member 50 can still isolate the high-temperature substances from the electrode assembly 10 to a certain extent.

[0169] In some embodiments, the projection of the pressure relief portion 42 is located within the projection of the protective member 50 in the thickness direction Z. The protective member 50 can shield the pressure relief portion 42 from the inside. Even if the pressure relief portion 42 is melted through by a high-temperature substance, the protective member 50 can still isolate the high-temperature substance from the electrode assembly 10.

[0170] For example, compared with the weak portion 41 , the pressure relief portion 42 has a larger area, and the risk of external high-temperature substances falling on the pressure relief portion 42 is higher; the protective component 50 preferably shields the pressure relief portion 42 from the inside.

[0171] In some embodiments, the wall portion 20 a is provided with a pressure relief hole 221 , and the pressure relief hole 221 passes through the wall portion 20 a along the thickness direction Z.

[0172] The central axis of the pressure relief hole 221 may be parallel to the thickness direction Z, or may be inclined relative to the thickness direction Z.

[0173] The pressure relief hole 221 may be a circular hole, a square hole, an elliptical hole, a racetrack-shaped hole, or a through hole in other shapes.

[0174] In some embodiments, the pressure relief mechanism 40 is connected to the wall portion 20 a and covers the pressure relief hole 221 .

[0175] As an example, the pressure relief mechanism 40 may be located on the side of the pressure relief hole 221 facing the electrode assembly 10 to cover the pressure relief hole 221 from the inside. Alternatively, the pressure relief mechanism 40 may be located on the side of the pressure relief hole 221 facing away from the electrode assembly 10 to cover the pressure relief hole 221 from the outside.

[0176] As an example, the pressure relief mechanism 40 and the wall portion 20a are independently formed components, and the pressure relief mechanism 40 can be connected to the wall portion 20a by welding, bonding or other methods. Optionally, the pressure relief mechanism 40 and the wall portion 20a are connected by welding.

[0177] In some embodiments, in the thickness direction Z, the projection of the pressure relief hole 221 is located within the projection of the protection member 50 .

[0178] External high-temperature substances need to pass through the pressure relief hole 221 before they can enter the interior of the housing 20. The protective member 50 can block the pressure relief hole 221 from the inside, isolating the high-temperature substances that pass through the pressure relief hole 221 from the electrode assembly 10 to a certain extent, thereby reducing the risk of short circuits and improving the reliability of the battery cell 6.

[0179] For example, the pressure relief mechanism 40 covers the pressure relief hole 221 from the inside. After a high-temperature substance enters the pressure relief hole 221, the portion of the pressure relief mechanism 40 corresponding to the pressure relief hole 221 will be subjected to the thermal shock of the high-temperature substance. In other words, the portion of the pressure relief mechanism 40 corresponding to the pressure relief hole 221 is more likely to be melted through. In the embodiment of the present application, the projection of the pressure relief hole 221 along the thickness direction Z is located within the projection of the protective member 50 along the thickness direction Z. Even if the portion of the pressure relief mechanism 40 corresponding to the pressure relief hole 221 is melted through, the protective member 50 can block the high-temperature substance, isolating the high-temperature substance from the electrode assembly 10, thereby improving the reliability of the battery cell 6.

[0180] In some embodiments, the battery cell 6 further includes a protective film 60, which is located outside the pressure relief hole 221 and connected to the wall portion 20a. In the thickness direction Z, the protective film 60 covers at least a portion of the pressure relief hole 221. The protective film 60 can partially seal the pressure relief hole 221, reducing the amount of impurities that fall into the pressure relief hole 221 and reducing the risk of impurities corroding the pressure relief mechanism 40.

[0181] In addition, the protective film 60 has a low melting point and low strength. When the battery cell 6 experiences thermal runaway, the protective film 60 is easily broken by the material inside the battery cell 6 , which has little effect on the pressure relief of the battery cell 6 .

[0182] In some embodiments, the pressure relief mechanism 40 includes a connecting portion 43, and the weak portion 41 connects the pressure relief portion 42 and the connecting portion 43. The connecting portion 43 can be connected to the wall portion 20a, for example, the connecting portion 43 is welded to the wall portion 20a.

[0183] In some embodiments, in the thickness direction Z, the projection of the pressure relief mechanism 40 is located within the projection of the protection member 50 , thereby reducing the risk of short circuit and improving the reliability of the battery cell 6 .

[0184] In some embodiments, the protective member 50 includes a first region 51 and a second region 52 surrounding the first region 51 , wherein the first region 51 completely overlaps the pressure relief mechanism 40 in the thickness direction Z. A width W of the second region 52 is 0.5 mm to 10 mm.

[0185] Optionally, W is 0.5 mm, 0.8 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm, 4.0 mm, 5.0 mm, 6.0 mm, 7.0 mm, 8.0 mm, 9.0 mm or 10 mm.

[0186] Limiting W to greater than or equal to 0.5 mm can reduce the risk of the protective member 50 not completely covering the pressure relief mechanism 40 due to assembly errors. Limiting W to less than or equal to 10 mm reduces the resistance of the protective member 50 to escape from the housing 20 when the pressure relief mechanism 40 is actuated, thereby reducing the barrier of the protective member 50 to internal substances and improving pressure relief efficiency.

[0187] In some embodiments, the thickness of the protective member 50 is greater than the thickness of the pressure relief mechanism 40 to reduce the risk of the protective member 50 being melted through by high-temperature substances and improve the reliability of the battery cell 6.

[0188] Optionally, the thickness of the protection member 50 is 1.5 to 10 times the thickness of the pressure relief portion 42 .

[0189] In some embodiments, the protective member 50 has a thickness of 0.4 mm to 2 mm.

[0190] Illustratively, the thickness of the protection member 50 is 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 1 mm, 1.2 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.8 mm, or 2 mm.

[0191] The thickness of the protective member 50 is limited to greater than or equal to 0.4 mm to reduce the risk of the protective member 50 being melted through by high-temperature materials, thereby improving the reliability of the battery cell 6. The thickness of the protective member 50 is limited to less than or equal to 2 mm to reduce the difficulty of deformation of the protective member 50 when the pressure relief mechanism 40 is activated, thereby allowing the protective member 50 to be removed from the housing 20 in a timely manner, reducing the barrier of the protective member 50 to internal materials and improving pressure relief efficiency.

[0192] In some embodiments, the thickness of the protective member 50 is 0.5 mm to 1.5 mm.

[0193] In some embodiments, the melting point of the protection member 50 is greater than or equal to 250°C.

[0194] The melting point of the protective member 50 refers to the melting point of the protective member 50 under atmospheric pressure. Alternatively, the melting point of the protective member 50 may be 250, 300, 500, 700, 900, 1000, 1500, 2000, or 2500°C.

[0195] The melting point of the protective component 50 is greater than or equal to 250°C, and it can withstand higher thermal shock. When the high-temperature material melts through the pressure relief mechanism 40 and contacts the protective component 50, the protective component 50 can withstand the thermal shock of the high-temperature material and is not prone to deformation, melting through and other problems under the action of high temperature, thereby separating at least part of the high-temperature material from the electrode assembly 10 and reducing the risk of short circuit.

[0196] In some embodiments, the melting point of the protection member 50 is greater than or equal to 300°C.

[0197] In some embodiments, the elastic modulus of the protection member 50 is less than or equal to 4500 MPa. For example, the elastic modulus may refer to Young's modulus.

[0198] As an example, the elastic modulus of the protective member 50 can be tested according to the national standard GB / T 1040.1-2018 "Determination of tensile properties of plastics".

[0199] Alternatively, the elastic modulus of the protection member 50 may be 4500 MPa, 4000 MPa, 3500 MPa, 3000 MPa, 2500 MPa, 2000 MPa, 1000 MPa, or 500 MPa.

[0200] The protective member 50 has a low elastic modulus. When thermal runaway occurs in the battery cell 6, the protective member 50 can adhere tightly to the pressure relief mechanism 40 under the internal pressure of the battery cell 6, thereby transmitting the internal pressure of the battery cell 6 to the pressure relief mechanism 40, allowing the pressure relief mechanism 40 to be activated in a timely manner. When the pressure relief mechanism 40 is activated, the protective member 50 can also deform and escape from the housing 20, thereby reducing the barrier effect of the protective member 50 on internal substances and improving pressure relief efficiency.

[0201] In some embodiments, the elastic modulus of the protective member 50 is less than or equal to 4000 MPa.

[0202] In some embodiments, the material of the protection component 50 is polyimide or polyethylene terephthalate, which has a relatively high melting point and is not easily melted through. In addition, these materials are not easily corroded by electrolytes.

[0203] In some embodiments, the battery cell 6 further includes an insulating member 70 . The insulating member 70 is disposed between the wall portion 20 a and the electrode assembly 10 . The insulating member 70 is connected to the wall portion 20 a and abuts against the electrode assembly 10 .

[0204] The insulating member 70 can separate the electrode assembly 10 from the wall portion 20a, thereby reducing the risk of the wall portion 20a causing electrical conduction between the positive and negative electrodes of the electrode assembly 10 and improving the reliability of the battery cell 6. When the battery cell 6 is subjected to an external impact, the insulating member 70 can limit the shaking of the electrode assembly 10 within the housing 20, thereby reducing the risk of failure in the connection between the electrode assembly 10 and other components and improving the reliability of the battery cell 6.

[0205] In some embodiments, the insulating member 70 is made of plastic.

[0206] In some embodiments, the insulating member 70 may be bonded to the wall portion 20 a .

[0207] In some embodiments, in the thickness direction Z, the insulating member 70 abuts against the electrode assembly 10 .

[0208] In some embodiments, the protection member 50 is disposed between the insulating member 70 and the pressure relief mechanism 40 in the thickness direction Z. The insulating member 70 can provide support for the protection member 50.

[0209] In some embodiments, the protection member 50 is connected to the insulating member 70 .

[0210] For example, the protection member 50 may be connected to the insulation member 70 by bonding, clamping, welding or other methods.

[0211] The insulating component 70 can limit the protective component 50, reduce the risk of the protective component 50 shifting in the shell 20, and enable the protective component 50 to cover the pressure relief mechanism 40 from the inside to block the high-temperature material that melts through the pressure relief mechanism 40.

[0212] In some embodiments, the protective member 50 is bonded to the insulating member 70. When the battery cell 6 experiences thermal runaway, the bond between the protective member 50 and the insulating member 70 tears under the action of the internal pressure and temperature of the battery cell 6, thereby separating the protective member 50 from the insulating member 70 and reducing the barrier effect of the protective member 50 on the internal substances of the battery cell 6.

[0213] Optionally, the protection member 50 is bonded to the insulation member 70 via an adhesive layer resistant to electrolyte corrosion.

[0214] Optionally, the protective member 50 has a connection surface on a side facing away from the pressure relief mechanism 40 , and at least a portion of the connection surface is bonded to the insulating member 70 via an adhesive layer.

[0215] In some embodiments, a recess 71 is formed on a side of the insulating member 70 facing the wall portion 20 a . At least a portion of the protective member 50 is received in the recess 71 .

[0216] The protection member 50 may be entirely housed in the recess 71 , or only partially housed in the recess 71 .

[0217] The recess 71 allows the insulating member 70 and the protective member 50 to share space in the thickness direction Z, thereby improving space utilization. When assembling the insulating member 70 and the protective member 50 , the recess 71 can position the protective member 50 , thereby simplifying the assembly process.

[0218] Optionally, when the recess 71 is provided, the recess 71 can limit the protective member 50 , and the protective member 50 can also be fixed to the insulating member 70 without being bonded, that is, the protective member 50 can be directly placed in the recess 71 .

[0219] In some embodiments, the protective member 50 is entirely housed in the recess 71. In the thickness direction Z, the protective member 50 does not protrude from the surface of the insulating member 70 facing the wall portion 20a, thereby reducing the risk of the protective member 50 interfering with the fit between the insulating member 70 and the wall portion 20a.

[0220] In some embodiments, the sidewall 72 of the recess has a stepped surface 72 a , and the protection member 50 abuts against and connects to the stepped surface 72 a .

[0221] The stepped surface 72a supports the protective member 50 and separates the bottom wall 73 of the recess from the protective member 50, thereby forming a thermal insulation cavity between the bottom wall 73 of the recess and the protective member 50. The thermal insulation cavity reduces the amount of heat transferred to the bottom wall 73 of the recess, thereby reducing the amount of heat transferred to the electrode assembly 10 and reducing the risk of short circuiting the electrode assembly 10. The provision of the stepped surface 72a reduces the connection area between the protective member 50 and the insulating member 70, making it easier to separate the protective member 50 from the insulating member 70 in the event of thermal runaway of the battery cell 6.

[0222] In some embodiments, the bottom wall 73 of the recess abuts against the electrode assembly 10 along the thickness direction Z.

[0223] In some embodiments, the protective member 50 is bonded to the stepped surface 72 a .

[0224] In some embodiments, the insulating member 70 is provided with a through hole 74 , and the through hole 74 is located on a side of the protective member 50 facing away from the pressure relief mechanism 40 .

[0225] Through-hole 74 connects to the space between insulating member 70 and electrode assembly 10. When battery cell 6 experiences thermal runaway, substances generated by electrode assembly 10 can act on protective member 50 through through-hole 74, exerting pressure on pressure relief mechanism 40 through protective member 50, causing timely activation of pressure relief mechanism 40 and forming a pressure relief channel. Substances generated by electrode assembly 10 can be quickly discharged to the exterior of battery cell 6 through through-hole 74 and the pressure relief channel.

[0226] In some embodiments, the bottom wall 73 of the recess is provided with a through hole 74 .

[0227] In some embodiments, the sidewall 72 of the recess is provided with a through hole 74 . For example, the through hole 74 is provided on the step surface 72 a .

[0228] In some embodiments, the melting point of the protective member 50 is higher than that of the insulating member 70. The protective member 50 has a higher melting point. When a high-temperature substance melts through the pressure relief mechanism 40, the protective member 50 can withstand the thermal shock of the high-temperature substance and is not easily melted through, thereby isolating at least a portion of the high-temperature substance from the electrode assembly 10 and reducing the risk of short circuit.

[0229] In some embodiments, the protective member 50 may or may not be in contact with the wall portion 20a in the thickness direction Z. Alternatively, the protective member 50 may be spaced apart from the wall portion 20a in the thickness direction Z. This can reduce the constraint of the wall portion 20a on the protective member 50 when the battery cell 6 experiences thermal runaway, allowing the protective member 50 to quickly separate from the insulating member 70.

[0230] In some embodiments, the specific heat capacity of the insulating member 70 is greater than or equal to 1600 J / (kg×° C.).

[0231] Optionally, the specific heat capacity of the insulating member 70 is 1600 J / (kg×℃), 1800 J / (kg×℃), 2000 J / (kg×℃), 2200 J / (kg×℃), 2400 J / (kg×℃), 2500 J / (kg×℃), 2600 J / (kg×℃), 2800 J / (kg×℃) or 3000 J / (kg×℃).

[0232] The insulating member 70 has a high specific heat capacity and can absorb a high amount of heat. If a high-temperature external material melts through the pressure relief mechanism 40 and adheres to the protective member 50, the insulating member 70 can absorb the heat from the high-temperature material through the protective member 50, thereby reducing the temperature rise of the protective member 50, lowering the risk of the protective member 50 melting through, and improving the reliability of the battery cell 6.

[0233] In some embodiments, the specific heat capacity of the insulating member 70 is greater than or equal to 2000 J / (kg×° C.).

[0234] In some embodiments, the wall portion 20a is an end cap 22. In other alternative embodiments, the housing 21 includes the wall portion 20a, which is opposite to the end cap 22, that is, the wall portion 20a may be the bottom wall of the housing 21.

[0235] In some embodiments, the protective member 50 is in the shape of a flat plate. Optionally, the protective member 50 has a uniform thickness.

[0236] FIG9 is a schematic partial cross-sectional view of a battery cell provided in some other embodiments of the present application.

[0237] As shown in FIG9 , in some embodiments, the wall portion 20 a is integrally formed with the pressure relief mechanism 40 . The pressure relief mechanism 40 is composed of a weakened portion 41 and a pressure relief portion 42 .

[0238] FIG10 is a schematic partial cross-sectional view of a battery cell provided in some other embodiments of the present application.

[0239] 10 , in some embodiments, the insulating member 70 includes an insulating base 70 a and a coating 70 b disposed on a surface of the insulating base 70 a. The coating 70 b has a greater specific heat capacity than the insulating base 70 a. In the thickness direction Z, a projection of the coating 70 b at least partially overlaps with a projection of the pressure relief mechanism 40.

[0240] The coating layer 70b may completely cover the insulating base 70a or may only cover a portion of the insulating base 70a.

[0241] The coating 70b and the protective component 50 can play a double-layer protection role. After the pressure relief mechanism 40 is melted through by external high-temperature substances, even if the high-temperature substances fall onto the coating 70b, the coating 70b can quickly absorb heat. The specific heat capacity of the coating 70b is high, and the temperature rise of the coating 70b is small, so it is not easy to be melted through.

[0242] In some embodiments, the protective member 50 is connected to the coating 70b. When external high-temperature materials fall onto the protective member 50, the coating 70b can absorb the heat of the protective member 50, reducing the temperature rise of the protective member 50 and the risk of the protective member 50 being melted through.

[0243] In some embodiments, the coating 70b has a higher melting point than the insulating substrate 70a. The coating 70b has a higher melting point and is less likely to be melted through, thereby isolating high-temperature substances from the electrode assembly 10 and improving reliability.

[0244] An embodiment of the present application further provides a battery, which includes a plurality of battery cells 6 provided by any of the aforementioned embodiments.

[0245] According to some embodiments of the present application, the present application further provides an electrical device comprising a battery according to any of the above embodiments, the battery being used to provide electrical energy to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery.

[0246] 3 to 8 , an embodiment of the present application provides a battery cell 6 , which includes an electrode assembly 10 , a housing 20 , a pressure relief mechanism 40 , a protective member 50 , and an insulating member 70 .

[0247] The outer shell 20 includes a shell 21 and an end cap 22. The shell 21 has an opening, and the end cap 22 is used to cover the opening. The shell 21 and the end cap 22 cooperate to form an internal cavity, which accommodates the electrode assembly 10. The end cap 22 is provided with a pressure relief hole 221, which passes through the end cap 22 along the thickness direction Z of the end cap 22. The pressure relief mechanism 40 is located on the side of the pressure relief hole 221 closest to the electrode assembly 10. In the thickness direction Z, the pressure relief mechanism 40 covers the pressure relief hole 221 from the inside.

[0248] The insulating member 70 is disposed between the wall portion 20a and the electrode assembly 10. The insulating member 70 is connected to the wall portion 20a and abuts against the electrode assembly 10. A recess 71 is formed on the side of the insulating member 70 facing the wall portion 20a.

[0249] The protection member 50 is housed in the recess 71 and connected to the insulating member 70. In the thickness direction Z, the projection of the pressure relief mechanism 40 is located within the projection of the protection member 50.

[0250] The melting point of the protection member 50 is greater than or equal to 250° C. The thickness of the protection member 50 is greater than the thickness of the pressure relief mechanism 40 .

[0251] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions within the scope of the claims.

Claims

1. A battery cell, comprising: a housing including a wall portion; an electrode assembly housed in the housing; a pressure relief mechanism, disposed on the wall; as well as A protective member, at least a portion of which is disposed between the pressure relief mechanism and the electrode assembly in a thickness direction of the wall portion.

2. The battery cell according to claim 1, wherein: The pressure relief mechanism includes a weak portion and a pressure relief portion surrounded by the weak portion; In the thickness direction, a projection of the pressure relief portion is located within a projection of the protection member, and a projection of the weak portion is located within a projection of the protection member.

3. The battery cell according to claim 1 or 2, wherein: The wall portion is provided with a pressure relief hole, the pressure relief hole passes through the wall portion along the thickness direction, and the pressure relief mechanism is connected to the wall portion and covers the pressure relief hole; In the thickness direction, a projection of the pressure relief hole is located within a projection of the protection member.

4. The battery cell according to any one of claims 1 to 3, wherein: In the thickness direction, a projection of the pressure relief mechanism is located within a projection of the protection member.

5. The battery cell according to claim 4, wherein: The protective member includes a first area and a second area surrounding the first area, wherein the first area completely overlaps with the pressure relief mechanism in the thickness direction; The width of the second region is 0.5 mm to 10 mm.

6. The battery cell according to any one of claims 1 to 5, wherein: The thickness of the protection member is greater than the thickness of the pressure relief mechanism.

7. The battery cell according to any one of claims 1 to 6, wherein: The thickness of the protective component is 0.4 mm to 2 mm; optionally, the thickness of the protective component is 0.5 mm to 1.5 mm.

8. The battery cell according to any one of claims 1 to 7, wherein: The melting point of the protection member is greater than or equal to 250°C. Optionally, the melting point of the protection member is greater than or equal to 300°C.

9. [Corrected 30.10.2024 according to Rule 91] A battery cell according to any one of claims 1 to 8, wherein: The elastic modulus of the protection member is less than or equal to 4500 MPa. Optionally, the elastic modulus of the protection member is less than or equal to 4000 MPa.

10. The battery cell according to any one of claims 1 to 9, wherein: The material of the protection component is polyimide or polyethylene terephthalate.

11. The battery cell according to any one of claims 1 to 10, further comprising an insulating member, the insulating member being disposed between the wall portion and the electrode assembly, the insulating member being connected to the wall portion and abutting against the electrode assembly; In the thickness direction, the protection member is provided between the insulating member and the pressure relief mechanism.

12. The battery cell according to claim 11, wherein: The protection member is connected to the insulating member.

13. The battery cell according to claim 11 or 12, wherein: A recess is provided on one side of the insulating member facing the wall; At least a portion of the protection member is accommodated in the recess.

14. The battery cell according to claim 13, wherein: The protective member is entirely accommodated in the recess.

15. The battery cell according to claim 13 or 14, wherein: The side wall of the recess has a stepped surface, and the protection member abuts against and is connected to the stepped surface.

16. The battery cell according to any one of claims 11 to 15, wherein: The insulating component is provided with a through hole, and the through hole is located on a side of the protective component away from the pressure relief mechanism.

17. The battery cell according to any one of claims 11 to 16, wherein: The melting point of the protection member is higher than the melting point of the insulating member.

18. The battery cell according to any one of claims 11 to 17, wherein: The specific heat capacity of the insulating member is greater than or equal to 1600 J / (kg×°C); optionally, the specific heat capacity of the insulating member is greater than or equal to 2000 J / (kg×°C).

19. The battery cell according to any one of claims 11 to 18, wherein: The insulating member includes an insulating base and a coating provided on a surface of the insulating base, wherein the specific heat capacity of the coating is greater than the specific heat capacity of the insulating base; In the thickness direction, a projection of the coating layer at least partially overlaps with a projection of the pressure relief mechanism.

20. The battery cell according to claim 19, wherein The protective member is connected to the coating layer.

21. The battery cell according to claim 19 or 20, wherein: The melting point of the coating layer is higher than the melting point of the insulating substrate.

22. A battery, wherein: The invention comprises a plurality of battery cells according to any one of claims 1 to 21.

23. An electrical device, wherein: The battery according to claim 22 is included for providing electrical energy.

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