Battery cell, battery and electric device

Abstract

The utility model discloses a battery monomer, a battery and a power utilization device. The battery cell includes an electrode assembly, a housing, a pressure relief mechanism, and a protection member. The electrode assembly is housed within the housing. The housing includes a wall portion. The pressure relief mechanism is provided on the wall portion. At least a portion of the protection member is provided between the pressure relief mechanism and the electrode assembly in a thickness direction of the wall portion. When a high-temperature substance outside the battery monomer acts on the pressure relief mechanism and melts through the pressure relief mechanism, the protection component can bear thermal shock of the high-temperature substance, and at least part of the high-temperature substance is separated from the electrode assembly, so that the risk that the high-temperature substance conducts the positive electrode and the negative electrode of the electrode assembly is reduced, and the reliability of the battery monomer is improved.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Art

[0002] With the development of battery technology, battery cells are used in more and more fields and are gradually replacing traditional petrochemical energy in the field of automotive power. Battery cells can store chemical energy and controllably convert chemical energy into electrical energy. In recyclable battery cells, the active material can be activated by charging after discharge and continue to be used.

[0003] How to improve the reliability of battery cells is an important research direction in the industry. Utility Model Content

[0004] The present application provides a battery cell, a battery, and an electrical device, which can improve reliability.

[0005] In a first aspect, the present application provides a battery cell, which includes an electrode assembly, a housing, a pressure relief mechanism, and a protective member. The electrode assembly is accommodated in the housing. The housing includes a wall portion. The pressure relief mechanism is disposed on the wall portion. In the thickness direction of the wall portion, at least a portion of the protective member is disposed between the pressure relief mechanism and the electrode assembly.

[0006] When a battery cell experiences thermal runaway, the internal pressure of the battery cell can be transmitted to the pressure relief mechanism through the protective component, so that the pressure relief mechanism is activated in time; the pressure relief mechanism is activated and releases the material in the shell to the outside, thereby reducing the risk of explosion and fire of the battery cell and improving the reliability of the battery cell. When the high-temperature material outside the battery cell acts on the pressure relief mechanism and melts through the pressure relief mechanism, the protective component can withstand the thermal shock of the high-temperature material and separate at least part of the high-temperature material from the electrode assembly, reducing the risk of the high-temperature material conducting the positive and negative electrodes of the electrode assembly and improving the reliability of the battery cell.

[0007] 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.

[0008] 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.

[0009] In one or more of the above optional embodiments, the wall is provided with a pressure relief hole, the pressure relief hole penetrates the wall along the thickness direction, and the pressure relief mechanism is connected to the wall and covers the pressure relief hole. In the thickness direction, the projection of the pressure relief hole is located within the projection of the protective member. The protective member can shield the pressure relief hole from the inside, and to a certain extent, separate the high-temperature material passing through the pressure relief hole from the electrode assembly, thereby reducing the risk of short circuit and improving the reliability of the battery cell.

[0010] 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.

[0011] 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 the pressure relief mechanism in the thickness direction, and the width W of the second region is 0.5 mm-10 mm.

[0012] Limiting W to be greater than or equal to 0.5 mm can reduce the risk of the protective member not completely covering the pressure relief mechanism due to assembly error. Limiting W to be less than or equal to 10 mm can reduce the resistance of the protective member to escape from the housing when the pressure relief mechanism is actuated, reduce the obstruction of the protective member to the internal substances, and improve the pressure relief efficiency.

[0013] In one or more of the above optional embodiments, the thickness of the protection component is greater than the thickness of the pressure relief mechanism, so as to reduce the risk of the protection component being melted through by high-temperature substances and improve the reliability of the battery cell.

[0014] In one or more of the above optional embodiments, the thickness of the protection member is 0.4 mm-2 mm; optionally, the thickness of the protection member is 0.5 mm-1.5 mm.

[0015] The thickness of the protective member is limited to be greater than or equal to 0.4 mm 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 be less than or equal to 2 mm to reduce the difficulty of deformation of the protective member when the pressure relief mechanism is actuated, thereby allowing the protective member to be removed from the housing in a timely manner, reducing the barrier of the protective member to the internal substances and improving the pressure relief efficiency.

[0016] 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.

[0017] 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, and other problems under high temperature, thereby isolating at least part of the high-temperature material from the electrode assembly and reducing the risk of short circuit.

[0018] In one or more of the above optional embodiments, 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.

[0019] The elastic modulus of the protective component is relatively small. When the battery cell experiences thermal runaway, the protective component can be in close contact with 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, so that the pressure relief mechanism can be actuated in time. When the pressure relief mechanism is actuated, the protective component can also be deformed and detached from the shell, thereby reducing the barrier of the protective component to the internal substances and improving the pressure relief efficiency.

[0020] In one or more of the above optional embodiments, the material of the protection 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.

[0021] 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 the insulating member is connected to the wall portion and abuts against the electrode assembly.

[0022] The insulating member can separate the electrode assembly from the wall to reduce the risk of the wall conducting the positive and negative electrodes of the electrode assembly, thereby improving the reliability of the battery cell. When the battery cell is subjected to external impact, the insulating member can limit the shaking of the electrode assembly in the housing, thereby reducing the risk of failure in the connection between the electrode assembly and other components, thereby improving the reliability of the battery cell.

[0023] In one or more optional embodiments above, in the thickness direction, the protective member is disposed between the insulating member and the pressure relief mechanism, and the insulating member can provide support for the protective member.

[0024] In one or more optional embodiments above, the protective component is connected to the insulating component. The insulating component can limit the protective component, reduce the risk of the protective component shifting in the shell, and enable the protective component to cover the pressure relief mechanism from the inside to shield the high-temperature material that melts through the pressure relief mechanism.

[0025] In one or more optional embodiments above, a recess is provided on one side of the insulating member facing the wall. At least a portion of the protective member is accommodated in the recess. By providing the recess, the insulating member and the protective member can share a space in the thickness direction, thereby improving space utilization. When assembling the insulating member and the protective member, the recess can position the protective member, thereby simplifying the assembly process.

[0026] 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.

[0027] In one or more of the above optional embodiments, the side wall of the recess has a step surface, and the protection member abuts against and is connected to the step surface.

[0028] The step surface can support the protection member and separate the bottom wall of the recess from the protection member, thereby forming a heat-insulating cavity between the bottom wall of the recess and the protection member; the heat-insulating cavity can reduce the heat transferred to the bottom wall of the recess, thereby reducing the heat conducted to the electrode assembly and reducing the risk of short circuit of the electrode assembly. By providing the step surface, the connection area between the protection member and the insulating member can be reduced, reducing the difficulty of separating the protection member from the insulating member when the battery cell is in thermal runaway.

[0029] 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.

[0030] The through hole is connected to the space between the insulating member and the electrode assembly. When the battery cell is in thermal runaway, the substances generated by the electrode assembly can act on the protective member through the through hole, and the pressure relief mechanism is pressed by the protective member, so that the pressure relief mechanism is activated in time and a pressure relief channel is formed. The substances generated by the electrode assembly can be quickly discharged to the outside of the battery cell through the through hole and the pressure relief channel.

[0031] In one or more optional embodiments above, the melting point of the protective member is higher than the melting point of the insulating member. The melting point of the protective member has a higher melting point. When the 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 easy to melt through, thereby isolating at least part of the high-temperature substance from the electrode assembly and reducing the risk of short circuit.

[0032] 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×℃); optionally, the specific heat capacity of the insulating member is greater than or equal to 2000 J / (kg×℃). The insulating member has a higher specific heat capacity, which can absorb a higher 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.

[0033] In one or more optional embodiments above, the insulating member includes an insulating substrate and a coating disposed on the surface of the insulating substrate, and 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 overlaps at least partially with the projection of the pressure relief mechanism. The coating and the protective member can play a double-layer protection role. After the pressure relief mechanism is melted through by an external high-temperature substance, even if the high-temperature substance falls onto the coating, the coating can quickly absorb heat, the specific heat capacity of the coating is high, the temperature rise of the coating is small, and it is not easy to be melted through.

[0034] In one or more of the above optional embodiments, the protective component is connected to the coating. When external high-temperature substances fall onto the protective component, the coating can absorb the heat of the protective component, reduce the temperature rise of the protective component, and reduce the risk of the protective component being melted through.

[0035] In one or more optional embodiments above, 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 the high-temperature material from the electrode assembly and improving reliability.

[0036] 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.

[0037] In a third aspect, the present application provides an electrical device, comprising a battery provided according to any embodiment of the second aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0039] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0040] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0041] Figure 3 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0042] Figure 4 A schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application;

[0043] Figure 5 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0044] Figure 6 for Figure 5 An enlarged schematic diagram at the circle frame;

[0045] Figure 7 for Figure 6 An enlarged schematic diagram at the circle frame;

[0046] Figure 8 A schematic diagram of the structure of a protective component of a battery cell provided in some embodiments of the present application;

[0047] Fig. 9 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application;

[0048] Fig.10 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application.

[0049] In the drawings, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. 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 and secondary relationship.

[0052] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0053] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0054] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0055] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0056] The term "plurality" used in the present application refers to two or more (including two).

[0057] In the embodiment of the present application, the battery cell may be a secondary battery cell, which refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0058] The battery cells can be lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-hydrogen battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc., which are not limited in the embodiments of the present application.

[0059] A battery cell generally includes an electrode assembly, which includes a positive electrode and a negative electrode.

[0060] During the charge and discharge process of a battery cell, active ions (such as lithium ions) are inserted and removed back and forth between the positive electrode and the negative electrode. The separator is arranged between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing the active ions to pass through.

[0061] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet 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.

[0062] 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 disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0063] 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, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base 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.).

[0064] 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 positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include but are not limited to lithium iron phosphate (such as Li FePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as Li MnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and at least one of 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 Li CoO2), lithium nickel oxide (such as Li NiO2), lithium manganese oxide (such as Li MnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as Li Ni 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also referred to as NCM 333 )、Li Ni 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、Li Ni 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、Li Ni 0.6 Co 0.2 Mn0.2 O2 (also referred to as NCM 622 )、L i Ni 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as Li Ni 0.80 Co 0.15 A l 0.05 O2) and its modified compounds, etc.

[0065] In some embodiments, the positive electrode may be a foamed metal or a foamed carbon. The foamed metal may be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, etc. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0066] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0067] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The foamed metal can be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon, etc. The composite current collector can include a polymer material base 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.).

[0068] 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.

[0069] 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 disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0070] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells 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.

[0071] 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.

[0072] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0073] In some embodiments, the separator is a separator membrane. The separator membrane of the present application can be any known porous separator membrane with good chemical stability and mechanical stability.

[0074] As an example, the main 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. When the separator is a multi-layer composite film, the materials of each layer can be the same or different. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0075] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0076] In some embodiments, the battery cell further includes an electrolyte, which plays a role in conducting ions between the positive and negative electrodes. The electrolyte can be selected according to the requirements of the present application. The electrolyte can be liquid, gel or solid.

[0077] The liquid electrolyte includes an electrolyte salt and a solvent.

[0078] In some embodiments, the electrolyte salt can 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.

[0079] 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, methyl propyl carbonate, ethyl propyl 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 selected from ether solvents. 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.

[0080] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0081] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0082] 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, and the like.

[0083] As an example, the inorganic solid electrolyte can be an oxide solid electrolyte (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous Li PON 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.

[0084] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0085] 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.

[0086] In some embodiments, the electrode assembly is a laminate structure.

[0087] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0088] 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.

[0089] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0090] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0091] As an example, the separator may be disposed continuously, and disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0092] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0093] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0094] In some embodiments, the 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 (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0095] As an example, the battery cell may be a cylindrical battery cell, a prismatic battery cell, a soft-pack battery cell or a battery cell of other shapes. The prismatic battery cell includes a square-shell battery cell, a blade-shaped battery cell, a polygonal battery cell, such as a hexagonal battery cell.

[0096] 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.

[0097] 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.

[0098] 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 accommodated in the case.

[0099] 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.

[0100] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0101] The development of battery technology must take into account many 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.

[0102] The pressure relief mechanism on the battery cell has an important impact on the reliability of the battery cell. For example, when a short circuit or overcharge occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure. In this case, the pressure relief mechanism can be activated to release the internal pressure to the outside, thereby reducing the risk of battery cell explosion and fire.

[0103] The pressure relief mechanism refers to an element or component that is activated to release internal gas when the internal pressure or temperature of the battery cell reaches a predetermined threshold. The threshold design varies according to different design requirements. The threshold may depend on one or more materials of the positive electrode sheet, negative electrode sheet, electrolyte and separator in the battery cell.

[0104] The pressure relief mechanism may be in the form of an explosion-proof valve, an air valve, a pressure relief valve or a safety valve, and may specifically be a pressure-sensitive element or structure, that is, when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or a weak area provided in the pressure relief mechanism ruptures, thereby forming an opening or channel for internal pressure relief. Alternatively, the pressure relief mechanism may also be a temperature-sensitive element or structure, that is, when the internal temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action, thereby forming an opening or channel for internal pressure relief.

[0105] The "actuation" mentioned in this application means that the pressure relief mechanism is in action or activated to a certain state, so that the internal pressure of the battery cell can be released. The action produced by the pressure relief mechanism may include but is not limited to: at least a part 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 from the actuated part as emissions. In this way, the battery cell can be depressurized under controllable pressure, thereby avoiding potential more serious accidents.

[0106] 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 produced by the reaction, flames, and the like.

[0107] There are usually multiple battery cells arranged in a battery. When a battery cell experiences thermal runaway, the high-temperature substances (such as high-temperature gas, high-temperature particles, etc.) inside the battery cell are released after the pressure relief mechanism is activated; the released high-temperature gas and particles will rebound and impact the adjacent normal battery cells, thereby damaging the pressure relief mechanism of the adjacent battery cells. In severe cases, the pressure relief mechanism of the normal battery cell is melted through, and the high-temperature particles enter the normal battery cell, causing the originally normal battery cell to short-circuit and produce thermal runaway, causing heat spread and affecting the reliability of the battery.

[0108] 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.

[0109] The battery cells described in the embodiments of the present application are suitable for use in batteries and electrical devices using the batteries.

[0110] 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. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. 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, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0111] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0112] Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0113] like Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed 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 be used as an operating power source for the vehicle 1.

[0114] The vehicle 1 may further include a controller 3 and a motor 4 , wherein 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 starting, navigating, and driving the vehicle 1 .

[0115] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0116] Figure 2 Schematic diagram of an explosion of a battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the box body 5 .

[0117] The box 5 is used to accommodate the battery cell 6, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b jointly define a storage space 5c for accommodating the battery cell 6. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-like structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b can also be hollow structures with one side open, and the open side of the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c. Of course, the first box portion 5a and the second box portion 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0118] In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

[0119] 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.

[0120] In the battery 2, there can be one or more battery cells 6. If there are more than one battery cell 6, the battery cells 6 can be connected in series, in parallel or in mixed connection. Mixed connection means that the battery cells 6 are both connected in series and in parallel. The battery cells 6 can be directly connected in series, in parallel or in mixed connection, and then the whole formed by the battery cells 6 can be accommodated in the box 5; of course, the battery cells 6 can also be connected in series, in parallel or in mixed connection to form a battery module, and then the battery modules can be connected in series, in parallel or in mixed connection to form a whole, and then accommodated in the box 5.

[0121] Figure 3 An exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 4 A schematic diagram of a partial structure of a battery cell provided in some embodiments of the present application; Figure 5 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application; Figure 6 for Figure 5 An enlarged schematic diagram at the circle frame;

[0122] Figure 7 for Figure 6 An enlarged schematic diagram at the circle frame; Figure 8 This is a schematic diagram of the structure of the protective component of the battery cell provided in some embodiments of the present application. It is explained here that: Figure 8The dotted line in the figure is to show the boundary position between the first area and the second area of ​​the protective member. In the actual protective member, there is no such boundary position. Figure 8 Dotted line shown.

[0123] Reference Figures 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 .

[0124] The housing 20 is a hollow structure, and a space for accommodating the electrode assembly 10 and the electrolyte is formed therein. The shape of the housing 20 can be determined according to 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 selected; if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be selected.

[0125] 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.

[0126] The shell 21 cooperates with the end cover 22 to form an internal cavity of the battery cell 6 , and the formed internal cavity can be used to accommodate the electrode assembly 10 , electrolyte and other components.

[0127] The housing 21 and the end cap 22 may be independent components. For example, an opening may be provided on the housing 21, and the end cap 22 may cover the opening to form an internal cavity of the battery cell 6.

[0128] The shell 21 can be in various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.

[0129] The shape of the end cap 22 can be adapted to the shape of the shell 21 to match the shell 21. The material of the end cap 22 can be the same as or different from the material of the shell 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when squeezed and collided, so that the battery cell 6 can have a higher structural strength and the reliability performance can also be improved.

[0130] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0131] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be a structure with an opening at one end, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may be a structure with openings at both ends, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

[0132] Exemplarily, 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 inverted, the end cap 22 is located below the electrode assembly 10 along the direction of gravity.

[0133] 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.

[0134] As an example, the electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly 10, and the portions of the positive electrode sheet and the negative electrode sheet not having active materials each constitute a tab 11. The tab 11 may include a positive tab and a negative tab. The positive tab and the negative tab may be located at the same end of the main body or at both ends of the main body, respectively.

[0135] In some embodiments, the end cap 22 is provided with an injection hole 222, and 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, which is connected to the end cap 22 and used to seal the injection hole 222.

[0136] 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 be electrically connected to the electrode assembly 10 to output or input electrical energy of the battery cell 6.

[0137] 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.

[0138] 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.

[0139] In some embodiments, the battery cell 6 further includes a transfer sheet 80 , which connects the electrode terminal 30 and the tab 11 .

[0140] 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 .

[0141] As an example, the wall portion 20 a may be an end cover 22 , or may be a wall of the housing 21 .

[0142] As an example, the shape of the wall portion 20a may be circular, rectangular, oval, or other shapes.

[0143] In some examples, the pressure relief mechanism 40 and the wall portion 20a may be independently formed components, and the two may be connected by welding, bonding or other methods. For example, the wall portion 20a is provided with a pressure relief hole 221, and the pressure relief hole 221 passes through the wall portion 20a. The pressure relief mechanism 40 is installed on the wall portion 20a and covers the pressure relief hole 221 to separate the space on the inner and outer sides of the wall portion 20a. In an alternative embodiment, the pressure relief mechanism 40 and the wall portion 20a may also be an integrally formed structure.

[0144] Exemplarily, the pressure relief mechanism 40 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the substance in 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.

[0145] 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 releasing 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, debris, etc. can also be released.

[0146] 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 .

[0147] 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 .

[0148] As an example, when the battery cell 6 is in thermal runaway, as the gas in the housing 20 continues to accumulate, the internal pressure of the housing 20 may reach or even exceed the pressure threshold. When the internal pressure of the housing 20 reaches the threshold, the pressure relief mechanism 40 is actuated to form a pressure relief channel, so that the internal space of the housing 20 is connected to the external space, and the gas inside the housing 20 can be discharged through the pressure relief channel, thereby reducing the risk of explosion of the battery cell 6.

[0149] As an example, when the electrolyte and active material react and release heat quickly, the internal temperature of the housing 20 will rise, and the temperature rise will also cause the internal pressure of the housing 20 to rise. When the internal temperature of the housing 20 reaches a threshold, the pressure relief mechanism 40 can be actuated under the action of temperature and pressure to form a pressure relief channel, so that the internal space of the housing 20 is connected with the external space, and the gas inside the housing 20 can be discharged through the pressure relief channel, thereby reducing the risk of explosion of the battery cell 6.

[0150] In some embodiments, the electrode terminal 30 is mounted on the wall portion 20 a.

[0151] In some embodiments, the 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 accommodated in the housing 20. The pressure relief mechanism 40 is disposed in the wall portion 20a. In the thickness direction Z of 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.

[0152] In the thickness direction Z of the wall portion 20 a , the protection 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 .

[0153] 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.

[0154] The protection member 50 may be connected to the wall portion 20 a or may be provided independently of the wall portion 20 a. The protection member 50 may be connected to the pressure relief mechanism 40 or may be provided independently of the pressure relief mechanism 40.

[0155] As an example, when the pressure relief mechanism 40 is actuated, the protection member 50 may be broken, shattered, opened, flew out, or undergo other actions under the internal pressure of the battery cell 6 to reduce the barrier of the protection member 50 to the internal substances of the housing 20 .

[0156] As an example, the protection member 50 is accommodated in the housing 20 .

[0157] 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 component 50, so that the pressure relief mechanism 40 is activated in time; the pressure relief mechanism 40 is activated and releases the material in the housing 20 to the outside, so as to reduce the risk of explosion and fire of the battery cell 6 and improve the reliability of the battery cell 6. When the 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 component 50 can withstand the thermal shock of the high-temperature material and separate at least part of the high-temperature material from the electrode assembly 10, reducing the risk of the high-temperature material conducting 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, so that the positive and negative electrodes of the electrode assembly 10 are conducted), and improving the reliability of the battery cell 6.

[0158] Compared with the solution of setting the protection component on the outside of the pressure relief mechanism, setting the protection component on the inside of the pressure relief mechanism can reduce the risk of the protection component being damaged by external impurities.

[0159] 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 with relatively low strength, which 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 less than the strength of the portion of the pressure relief mechanism 40 that is close to the weak portion 41.

[0160] In some examples, a groove, notch or other structure may be provided in a predetermined area 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 is performed on a predetermined area 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 process may be performed on a predetermined area of ​​the pressure relief mechanism 40, so that the strength of the area is weaker than that of other areas. In other words, the area is the weak portion 41.

[0161] The weak portion 41 can be ruptured when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the substance in the housing 20 .

[0162] In some embodiments, the pressure relief mechanism 40 includes a pressure relief portion 42 surrounded by a weak portion 41 .

[0163] In some examples, the weak portion 41 is annular and surrounds the pressure relief portion 42. In other examples, the two 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.

[0164] 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 .

[0165] 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 .

[0166] The weak portion 41 has a 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 separate the high-temperature substances from the electrode assembly 10 to a certain extent.

[0167] In some embodiments, in the thickness direction Z, the projection of the pressure relief portion 42 is located within the projection of the protection member 50. The protection member 50 can shield the pressure relief portion 42 from the inside, and even if the pressure relief portion 42 is melted through by a high-temperature substance, the protection member 50 can separate the high-temperature substance from the electrode assembly 10.

[0168] Exemplarily, 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.

[0169] In some embodiments, the wall portion 20 a is provided with a pressure relief hole 221 , and the pressure relief hole 221 penetrates the wall portion 20 a along the thickness direction Z.

[0170] 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.

[0171] 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.

[0172] In some embodiments, the pressure relief mechanism 40 is connected to the wall portion 20 a and covers the pressure relief hole 221 .

[0173] 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.

[0174] 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.

[0175] 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 .

[0176] External high-temperature substances need to pass through the pressure relief hole 221 to enter the interior of the housing 20. The protective member 50 can shield the pressure relief hole 221 from the inside, and to a certain extent, separate the high-temperature substances passing through the pressure relief hole 221 from the electrode assembly 10, thereby reducing the risk of short circuit and improving the reliability of the battery cell 6.

[0177] Exemplarily, the pressure relief mechanism 40 covers the pressure relief hole 221 from the inside. After the 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 shield the high-temperature substance, separate the high-temperature substance from the electrode assembly 10, and improve the reliability of the battery cell 6.

[0178] 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 part of the pressure relief hole 221. The protective film 60 can close the pressure relief hole 221 to a certain extent, reduce impurities falling into the pressure relief hole 221, and reduce the risk of the pressure relief mechanism 40 being corroded by impurities.

[0179] In addition, the protective film 60 has a low melting point and low strength. When the battery cell 6 is in 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 .

[0180] 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 may be connected to the wall portion 20a, for example, the connecting portion 43 is welded to the wall portion 20a.

[0181] In some embodiments, in the thickness direction Z, the projection of the pressure relief mechanism 40 is located within the projection of the protection component 50 , thereby reducing the risk of short circuit and improving the reliability of the battery cell 6 .

[0182] In some embodiments, the protection member 50 includes a first region 51 and a second region 52 surrounding the first region 51 , and 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-10 mm.

[0183] 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.

[0184] By limiting W to be greater than or equal to 0.5 mm, the risk of the protective member 50 not completely covering the pressure relief mechanism 40 due to assembly errors can be reduced. By limiting W to be less than or equal to 10 mm, the resistance of the protective member 50 to escape from the housing 20 when the pressure relief mechanism 40 is actuated can be reduced, the barrier of the protective member 50 to internal substances can be reduced, and the pressure relief efficiency can be improved.

[0185] In some embodiments, the thickness of the protection component 50 is greater than the thickness of the pressure relief mechanism 40 to reduce the risk of the protection component 50 being melted through by high-temperature substances and improve the reliability of the battery cell 6 .

[0186] Optionally, the thickness of the protection member 50 is 1.5 to 10 times the thickness of the pressure relief portion 42 .

[0187] In some embodiments, the thickness of the protective member 50 is 0.4 mm-2 mm.

[0188] 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.

[0189] The thickness of the protective member 50 is limited to be greater than or equal to 0.4 mm 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. The thickness of the protective member 50 is limited to be 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 actuated, 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 the internal substances and improving the pressure relief efficiency.

[0190] In some embodiments, the thickness of the protective member 50 is 0.5 mm-1.5 mm.

[0191] In some embodiments, the melting point of the protection member 50 is greater than or equal to 250°C.

[0192] 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.

[0193] The melting point of the protective component 50 is greater than or equal to 250°C and can withstand high thermal shock. When a high-temperature substance 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 substance and is not prone to deformation, melting, and other problems under high temperature, thereby isolating at least part of the high-temperature substance from the electrode assembly 10 and reducing the risk of short circuit.

[0194] In some embodiments, the melting point of the protection member 50 is greater than or equal to 300°C.

[0195] In some embodiments, the elastic modulus of the protection member 50 is less than or equal to 4500 MPa. Exemplarily, the elastic modulus may refer to Young's modulus.

[0196] 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".

[0197] 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.

[0198] The elastic modulus of the protective member 50 is relatively small. When the battery cell 6 experiences thermal runaway, the protective member 50 can be in close contact with 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, so that the pressure relief mechanism 40 is activated in time. When the pressure relief mechanism 40 is activated, the protective member 50 can also be deformed and escape from the housing 20, thereby reducing the barrier of the protective member 50 to the internal substances and improving the pressure relief efficiency.

[0199] In some embodiments, the elastic modulus of the protection member 50 is less than or equal to 4000 MPa.

[0200] 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, and is not easily corroded by electrolytes.

[0201] In some embodiments, the battery cell 6 further includes an insulating member 70 , which 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 .

[0202] The insulating member 70 can separate the electrode assembly 10 from the wall portion 20a to reduce the risk of the wall portion 20a conducting the positive and negative electrodes of the electrode assembly 10, thereby improving the reliability of the battery cell 6. When the battery cell 6 is subjected to external impact, the insulating member 70 can limit the shaking of the electrode assembly 10 in the housing 20, thereby reducing the risk of failure of the connection between the electrode assembly 10 and other components, thereby improving the reliability of the battery cell 6.

[0203] In some embodiments, the insulating member 70 is made of plastic.

[0204] In some embodiments, the insulating member 70 may be bonded to the wall portion 20 a .

[0205] In some embodiments, in the thickness direction Z, the insulating member 70 abuts against the electrode assembly 10 .

[0206] 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 may provide support for the protection member 50.

[0207] In some embodiments, the protection member 50 is connected to the insulating member 70 .

[0208] For example, the protection member 50 may be connected to the insulation member 70 by bonding, clamping, welding or other methods.

[0209] The insulating component 70 can limit the protective component 50 to reduce the risk of the protective component 50 being offset in the housing 20 , so that the protective component 50 can cover the pressure relief mechanism 40 from the inside and block the high-temperature material that melts through the pressure relief mechanism 40 .

[0210] In some embodiments, the protective member 50 is bonded to the insulating member 70. When the battery cell 6 is in thermal runaway, the bonding point between the protective member 50 and the insulating member 70 is torn under the action of the internal pressure and temperature of the battery cell 6, so that the protective member 50 is separated from the insulating member 70, reducing the barrier of the protective member 50 to the internal substances of the battery cell 6.

[0211] Optionally, the protection member 50 is bonded to the insulating member 70 via an adhesive layer resistant to electrolyte corrosion.

[0212] Optionally, the protection component 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 component 70 via an adhesive layer.

[0213] In some embodiments, a recess 71 is formed on one side of the insulating member 70 facing the wall portion 20 a . At least a portion of the protection member 50 is received in the recess 71 .

[0214] The protection member 50 may be entirely accommodated in the recess 71 , or only partially accommodated in the recess 71 .

[0215] By providing the recess 71 , the insulating member 70 and the protective member 50 can share a 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.

[0216] Optionally, when the recess 71 is provided, the recess 71 can limit the protection member 50 , and the protection member 50 may not be fixed to the insulating member 70 by bonding, that is, the protection member 50 may be directly placed in the recess 71 .

[0217] In some embodiments, the protective member 50 is entirely accommodated 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.

[0218] In some embodiments, the side wall 72 of the recess has a stepped surface 72 a , and the protection member 50 abuts against and is connected to the stepped surface 72 a .

[0219] The step surface 72a can support the protection member 50 and separate the bottom wall 73 of the recess from the protection member 50, thereby forming a heat-insulating cavity between the bottom wall 73 of the recess and the protection member 50; the heat-insulating cavity can reduce the heat transferred to the bottom wall 73 of the recess, thereby reducing the heat conducted to the electrode assembly 10, and reducing the risk of short circuit of the electrode assembly 10. By providing the step surface 72a, the connection area between the protection member 50 and the insulating member 70 can be reduced, and the difficulty of separating the protection member 50 from the insulating member 70 when the battery cell 6 is in thermal runaway can be reduced.

[0220] In some embodiments, the bottom wall 73 of the recess abuts against the electrode assembly 10 along the thickness direction Z.

[0221] In some embodiments, the protection member 50 is bonded to the step surface 72a.

[0222] 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 protection member 50 facing away from the pressure relief mechanism 40 .

[0223] The through hole 74 is connected to the space between the insulating member 70 and the electrode assembly 10. When the battery cell 6 is in thermal runaway, the substances generated by the electrode assembly 10 can act on the protective member 50 through the through hole 74, and the pressure relief mechanism 40 is pressed through the protective member 50, so that the pressure relief mechanism 40 is activated in time and a pressure relief channel is formed. The substances generated by the electrode assembly 10 can be quickly discharged to the outside of the battery cell 6 through the through hole 74 and the pressure relief channel.

[0224] In some embodiments, the bottom wall 73 of the recess is provided with a through hole 74 .

[0225] In some embodiments, the side wall 72 of the recess is provided with a through hole 74. Exemplarily, the through hole 74 is provided on the step surface 72a.

[0226] In some embodiments, the melting point of the protective member 50 is higher than the melting point of the insulating member 70. The melting point of the protective member 50 is relatively high. When the 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 easy to melt through, thereby isolating at least part of the high-temperature substance from the electrode assembly 10, reducing the risk of short circuit.

[0227] In some embodiments, the protective member 50 may or may not be in contact with the wall portion 20a in the thickness direction Z. Optionally, the protective member 50 is spaced apart from the wall portion 20a in the thickness direction Z, so that when the battery cell 6 is in thermal runaway, the restraint of the wall portion 20a on the protective member 50 can be reduced, so that the protective member 50 and the insulating member 70 are quickly separated.

[0228] In some embodiments, the specific heat capacity of the insulating member 70 is greater than or equal to 1600 J / (kg×° C.).

[0229] 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×℃).

[0230] The insulating member 70 has a high specific heat capacity and can absorb a high amount of heat. When the external high-temperature substance melts through the pressure relief mechanism 40 and adheres to the protective member 50, the insulating member 70 can absorb the heat of the high-temperature substance through the protective member 50, thereby reducing the temperature rise of the protective member 50, reducing the risk of the protective member 50 being melted through, and improving the reliability of the battery cell 6.

[0231] In some embodiments, the specific heat capacity of the insulating member 70 is greater than or equal to 2000 J / (kg×° C.).

[0232] In some embodiments, the wall portion 20a is an end cap 22. In other alternative embodiments, the housing 21 includes the wall portion 20a, and the wall portion 20a is opposite to the end cap 22, that is, the wall portion 20a may be the bottom wall of the housing 21.

[0233] In some embodiments, the protective member 50 is in the shape of a plate. Optionally, the protective member 50 has a uniform thickness.

[0234] Fig. 9 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application.

[0235] like Fig. 9 As shown, in some embodiments, the wall portion 20a is integrally formed with the pressure relief mechanism 40. The pressure relief mechanism 40 is composed of a weak portion 41 and a pressure relief portion 42.

[0236] Fig.10 A partial cross-sectional schematic diagram of a battery cell provided in some other embodiments of the present application.

[0237] Reference Fig.10In some embodiments, the insulating member 70 includes an insulating substrate 70a and a coating 70b disposed on the surface of the insulating substrate 70a, and the specific heat capacity of the coating 70b is greater than the specific heat capacity of the insulating substrate 70a. In the thickness direction Z, the projection of the coating 70b at least partially overlaps with the projection of the pressure relief mechanism 40.

[0238] The coating layer 70b may completely cover the insulating base 70a, or may only cover a portion of the insulating base 70a.

[0239] The coating 70b and the protective component 50 can play the role of double-layer protection. 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 coating 70b has a high specific heat capacity, and the temperature rise of the coating 70b is small, so it is not easy to be melted through.

[0240] In some embodiments, the protective member 50 is connected to the coating 70b. When external high-temperature substances fall onto the protective member 50, the coating 70b can absorb the heat of the protective member 50, reduce the temperature rise of the protective member 50, and reduce the risk of the protective member 50 being melted through.

[0241] In some embodiments, the melting point of the coating 70b is higher than that of the insulating substrate 70a. The coating 70b has a higher melting point and is not easily melted through, thereby isolating the high-temperature material from the electrode assembly 10 and improving reliability.

[0242] An embodiment of the present application also provides a battery, which includes a plurality of battery cells 6 provided by any of the aforementioned embodiments.

[0243] According to some embodiments of the present application, the present application further provides an electric device, comprising a battery in any of the above embodiments, the battery is used to provide electric energy to the electric device. The electric device can be any of the above-mentioned devices or systems using the battery.

[0244] Reference Figures 3 to 8 The 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 component 50 and an insulating component 70.

[0245] The housing 20 includes a housing 21 and an end cap 22. The housing 21 has an opening, and the end cap 22 is used to cover the opening. The housing 21 cooperates with the end cap 22 to form an internal cavity, and the electrode assembly 10 is accommodated in the internal cavity. The end cap 22 is provided with a pressure relief hole 221, and the pressure relief hole 221 penetrates 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 close to the electrode assembly 10, and in the thickness direction Z, the pressure relief mechanism 40 covers the pressure relief hole 221 from the inside.

[0246] 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 provided on one side of the insulating member 70 facing the wall portion 20a.

[0247] The protection member 50 is accommodated in the recessed portion 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.

[0248] 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 .

[0249] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: a housing, including a wall portion; an electrode assembly, contained in the housing; A pressure relief mechanism is arranged on the wall portion; as well as A protection 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, characterized in that: The pressure relief mechanism comprises 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.

3. The battery cell according to claim 1, characterized in that: The wall portion is provided with a pressure relief hole, the pressure relief hole penetrates 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, the projection of the pressure relief hole is located within the projection of the protection member.

4. The battery cell according to claim 1, characterized in that: 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, characterized in that: The protection member includes a first area and a second area surrounding the first area, and the first area completely overlaps with the pressure relief mechanism in the thickness direction; The width of the second region is 0.5 mm-10 mm.

6. The battery cell according to claim 1, characterized in that: The thickness of the protection component is greater than the thickness of the pressure relief mechanism.

7. The battery cell according to claim 1, characterized in that: The thickness of the protective component is 0.4 mm-2 mm.

8. The battery cell according to claim 7, characterized in that: The thickness of the protective component is 0.5 mm-1.5 mm.

9. The battery cell according to claim 1, characterized in that: The protective member has a melting point greater than or equal to 250°C.

10. The battery cell according to claim 9, characterized in that: The protective member has a melting point greater than or equal to 300°C.

11. The battery cell according to claim 1, characterized in that: The elastic modulus of the protection member is less than or equal to 4500 MPa.

12. The battery cell according to claim 11, characterized in that: The elastic modulus of the protection member is less than or equal to 4000 MPa.

13. The battery cell according to claim 1, characterized in that: The material of the protection component is polyimide or polyethylene terephthalate.

14. The battery cell according to any one of claims 1 to 13, characterized in that: The battery cell further includes 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 disposed between the insulating member and the pressure relief mechanism.

15. The battery cell according to claim 14, characterized in that: The protection member is connected to the insulating member.

16. The battery cell according to claim 14, characterized in that: 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.

17. The battery cell according to claim 16, characterized in that: The protection member is entirely accommodated in the recess.

18. The battery cell according to claim 16, characterized in that: The side wall of the recess has a stepped surface, and the protection member abuts against and is connected to the stepped surface.

19. The battery cell according to claim 14, characterized in that: The insulating component is provided with a through hole, and the through hole is located at a side of the protective component away from the pressure relief mechanism.

20. The battery cell according to claim 14, characterized in that: The protection member has a melting point higher than a melting point of the insulating member.

21. The battery cell according to claim 14, characterized in that: The specific heat capacity of the insulating member is greater than or equal to 1600 J / (kg×° C.).

22. The battery cell according to claim 21, characterized in that: The specific heat capacity of the insulating member is greater than or equal to 2000 J / (kg×° C.).

23. The battery cell according to claim 14, characterized in that: The insulating member comprises an insulating substrate and a coating disposed on the 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, a projection of the coating layer at least partially overlaps a projection of the pressure relief mechanism.

24. The battery cell according to claim 23, characterized in that: The protective member is connected to the coating layer.

25. The battery cell according to claim 23, characterized in that: The melting point of the coating layer is higher than the melting point of the insulating substrate.

26. A battery, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 25.

27. An electrical device, characterized in that: A battery according to claim 26, for providing electrical energy.

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