Battery cell, battery, and electric device

Abstract

The present application discloses a battery cell, a battery, and an electric device. The battery cell comprises a casing, a pressure relief mechanism, and a protection member. The casing comprises a wall part. The pressure relief mechanism is arranged on the wall part, and when the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief mechanism can be actuated to release gas in the casing. The melting point of the protection member is greater than or equal to 300°C, and in the thickness direction of the wall part, the protection member covers at least part of the pressure relief mechanism.

Description

Battery cells, batteries, and electrical devices

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310784350.0, filed on June 29, 2023, 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 the reliability of the battery cell.

[0008] In a first aspect, the present application provides a battery cell comprising a housing, a pressure relief mechanism, and a protective member. The housing includes a wall portion. The pressure relief mechanism is disposed in the wall portion and is actuated to release gas within the housing when the internal pressure or temperature of the battery cell reaches a threshold. The protective member has a melting point greater than or equal to 300°C and covers at least a portion of the pressure relief mechanism along the thickness of the wall portion.

[0009] When thermal runaway occurs in a battery cell, the pressure relief mechanism is activated and releases the gas in the casing to the outside, thereby reducing the risk of explosion or fire of the battery cell and improving the reliability of the battery cell. The protective component can isolate external impurities, reduce the corrosion or damage of the impurities to the pressure relief mechanism, and improve the reliability of the pressure relief mechanism. The melting point of the protective component is greater than or equal to 300°C and can withstand high thermal shock. When high-temperature materials flow through the battery cell, the protective component can withstand the thermal shock of the high-temperature materials and is not prone to deformation, melting through, and other problems under high temperature. It thus separates at least part of the high-temperature materials from the pressure relief mechanism, reduces the heat conducted to the pressure relief mechanism, reduces the risk of cracking and failure of the pressure relief mechanism, and improves the reliability of the battery cell.

[0010] In some embodiments, the wall portion has an outer surface, and the wall portion is provided with an accommodating recessed relative to the outer surface, and at least a portion of the protective member is accommodated in the accommodating recess.

[0011] By providing an accommodating recess and arranging at least a portion of the protective member in the accommodating recess, the space occupied by the battery cell in the thickness direction can be reduced, thereby improving the space utilization and energy density of the battery cell.

[0012] In some embodiments, the guard member is completely received in the receiving recess.

[0013] The embodiments of the present application can further improve the space utilization and energy density of the battery cell. In addition, by completely accommodating the protective member in the accommodating recess, the risk of friction between the protective member and external structures during the production, transportation, and use of the battery cell can be reduced, thereby improving the reliability of the protective member.

[0014] In some embodiments, the bottom wall of the receiving recess is provided with a through hole, and the pressure relief mechanism is housed in the receiving recess, connected to the bottom wall, and covering the through hole. The protective member and the pressure relief mechanism are spaced apart in the thickness direction. This embodiment of the present application can reduce the heat transfer rate between the protective member and the pressure relief mechanism when the protective member is subjected to thermal shock from high-temperature materials, thereby reducing the temperature rise of the pressure relief mechanism and the risk of cracking and failure of the pressure relief mechanism.

[0015] In some embodiments, there are no other components between the protective member and the pressure relief mechanism in the thickness direction.

[0016] An insulating cavity is formed between the protective member and the pressure relief mechanism to reduce the heat transfer rate between the two. The absence of any other physical components between the protective member and the pressure relief mechanism not only reduces gas obstruction when the pressure relief mechanism is actuated, but also, to a certain extent, prevents heat transfer from the physical structure between the protective member and the pressure relief mechanism, thereby reducing the heat transfer rate between the two.

[0017] In some embodiments, in the thickness direction, the minimum distance between the protective member and the pressure relief mechanism is D, and the minimum thickness of the protective member is t. D and t satisfy: t×D≥0.01mm 2 .

[0018] The larger t is, the lower the temperature of the protective component surface facing the pressure relief mechanism when a high-temperature object impacts the protective component, and the less heat the protective component radiates toward the pressure relief mechanism. The smaller t is, the higher the temperature of the protective component surface facing the pressure relief mechanism when a high-temperature object impacts the protective component, and the more heat the protective component radiates toward the pressure relief mechanism. The larger D is, the longer the heat transfer path between the protective component and the pressure relief mechanism when a high-temperature object impacts the protective component. The smaller D is, the shorter the heat transfer path between the protective component and the pressure relief mechanism.

[0019] In the embodiment of the present application, t×D is defined as greater than or equal to 0.01 mm. 2 , it can reduce the temperature rise of the pressure relief mechanism when high-temperature materials impact the protective components, and reduce the risk of cracking and failure of the pressure relief mechanism.

[0020] In some embodiments, t is between 0.05 mm and 0.4 mm. Limiting t to greater than or equal to 0.05 mm can reduce the heat radiated from the protective component to the pressure relief mechanism when a high-temperature material impacts the protective component, thereby lowering the temperature rise of the pressure relief mechanism. A larger t increases the space and weight occupied by the protective component. Limiting t to less than or equal to 0.4 mm can reduce the space and weight occupied by the protective component, while still meeting the required protection requirements, thereby increasing the energy density of the battery cell.

[0021] In some embodiments, t is 0.08 mm to 0.2 mm, so as to reduce the space and weight occupied by the protective component and improve the energy density of the battery cell while meeting the protection requirements of the protective component.

[0022] In some embodiments, the battery cell further comprises a connection layer, the protective member being connected to the wall portion via the connection layer, and the connection layer being actuable when the internal pressure or temperature of the battery cell reaches a threshold value to separate at least a portion of the protective member from the wall portion.

[0023] When the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief mechanism is activated and releases the gas in the outer shell. Under the action of other internal factors, at least part of the protective member is separated from the wall, thereby releasing the internal gas of the battery cell and reducing the internal pressure and temperature of the battery cell.

[0024] In some embodiments, the connecting layer includes a glue layer.

[0025] When the battery cell experiences thermal runaway, heat can be transferred to the connecting layer, causing the connecting layer to soften, thereby enabling the protective component to detach from the wall portion in time when the pressure relief mechanism is activated.

[0026] In some embodiments, the connecting layer is disposed on the peripheral area of ​​the surface of the protective member facing the pressure relief mechanism. Disposing the connecting layer on the peripheral area of ​​the protective member can save the amount of connecting layer and reduce the risk of the connecting layer connecting to the pressure relief mechanism.

[0027] In some embodiments, an escape space is formed between the protective component and the pressure relief mechanism, and a communication channel is provided between the protective component and the wall portion, one end of the communication channel is connected to the outside, and the other end is connected to the escape space.

[0028] During the charge and discharge process of a battery cell, the internal air pressure of the battery cell will experience small fluctuations. When the internal air pressure of the battery cell fluctuates, the pressure relief mechanism may bulge outward. The embodiments of the present application provide a connecting flow channel to connect the escape space with the external environment, thereby reducing the pressure fluctuation in the escape space when the pressure relief mechanism bulges and minimizing deformation of the protective component. Furthermore, during the production of the battery cell, the connecting flow channel and the escape space can also be used to test the airtightness of the pressure relief mechanism.

[0029] In some embodiments, the communication channel includes a groove provided on a surface of the protective member facing the pressure relief mechanism. The groove is provided on the surface of the pressure relief mechanism to connect the escape space with the external environment of the battery cell.

[0030] In some embodiments, the melting point of the protective member is greater than or equal to 500° C. The protective member has a high melting point and is not easily melted when subjected to thermal shock, thereby making the protective member have better thermal shock resistance and reducing the risk of the protective member being melted through.

[0031] In some embodiments, the protective member is made of mica, rubber, ceramic, or polyimide. These materials have good thermal shock resistance, thereby providing protection for the pressure relief mechanism and reducing the risk of failure or cracking of the pressure relief mechanism.

[0032] In some embodiments, the material of the protective component includes polyimide, and the tensile strength of the protective component at 150° C. is 100 MPa-350 MPa.

[0033] The greater the tensile strength of the protective member, the more difficult it is to rupture when the pressure relief mechanism is activated. In this embodiment of the application, the tensile strength of the protective member at 150°C is set to be less than or equal to 350 MPa, which can ensure that the protective member ruptures promptly when the pressure relief mechanism is activated, thereby improving exhaust efficiency.

[0034] The lower the tensile strength of the protective member, the greater its deformation during external air pressure fluctuations. Over time, the protective member is more susceptible to fatigue deformation. In this embodiment, the tensile strength of the protective member at 150°C is set to be greater than or equal to 100 MPa, which can slow down the aging of the protective member and extend the service life of the battery cell.

[0035] In some embodiments, the battery cell further includes an electrode assembly housed within the housing. The thickness of the wall portion is parallel to the direction of gravity, and the wall portion is located below the electrode assembly in the direction of gravity. The wall portion can provide support for the electrode assembly, improving its stability. In the event of thermal runaway of the battery cell, gas can be ejected downward, thereby reducing exhaust resistance and improving exhaust efficiency.

[0036] In some embodiments, the housing includes a shell and an end cap, wherein one end of the shell has an opening, and the end cap is connected to the shell and covers the opening; the shell includes a wall portion, and the wall portion is opposite to the end cap. Providing the pressure relief mechanism on the shell can reserve more installation space for components on the end cap.

[0037] In a second aspect, an embodiment of the present application provides a battery comprising a plurality of battery cells according to any one of the embodiments of the first aspect.

[0038] In some embodiments, the battery further comprises a housing housing the plurality of battery cells. The housing comprises a first wall, which is disposed at one end of the outer shell facing the first wall. A channel is defined within the first wall; the projection of the pressure relief mechanisms of the plurality of battery cells in the thickness direction is located within the projection of the channel. The protective member is located between the channel and the pressure relief mechanism in the thickness direction.

[0039] When a battery cell experiences thermal runaway, the pressure relief mechanism activates and releases gas from the casing into the channel. The channel guides the high-temperature gas flow and discharges it outside the casing, reducing the risk of battery explosion. As the hot gas flows through the channel, the protective component isolates it from the pressure relief mechanism, reducing the amount of heat transferred to it and the risk of cracking and failure. This simplifies the progression of thermal runaway and improves battery reliability.

[0040] In some embodiments, in the thickness direction, a projection of the guard member is located within a projection of the channel.

[0041] When the pressure relief mechanism is actuated, the protective component can enter the channel to release the gas in the shell; the embodiment of the present application can reduce the risk of the first box wall interfering with the protective component, allowing the protective component to smoothly enter the channel.

[0042] In some embodiments, in any direction perpendicular to the thickness direction, a dimension of the channel is larger than a dimension of the protective member.

[0043] The embodiments of the present application can reduce the problem of the first box wall interfering with the protective component due to assembly errors, so that the protective component can smoothly enter the channel when the battery cell experiences thermal runaway.

[0044] In a third aspect, the present application provides an electrical device comprising a battery according to any embodiment of the second aspect, the battery being configured to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0046] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application;

[0047] FIG2 is a schematic diagram of an explosion of a battery provided in some embodiments of the present application;

[0048] FIG3 is a schematic diagram of an explosion of a battery cell provided in some embodiments of the present application;

[0049] FIG4 is a schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0050] FIG5 is an enlarged schematic diagram of the circle frame of FIG4;

[0051] FIG6 is an enlarged schematic diagram of the box in FIG5;

[0052] FIG7 is an enlarged schematic diagram of the circle frame of FIG6;

[0053] FIG8 is an enlarged schematic diagram of the circle frame in FIG5;

[0054] FIG9 is a top view of a protective member and a connection layer of a battery cell provided in some embodiments of the present application;

[0055] FIG10 is a top view of a protective member and a connecting layer of a battery cell provided in some other embodiments of the present application;

[0056] FIG11 is a schematic cross-sectional view of the protective member and the connecting layer shown in FIG10 ;

[0057] FIG12 is a schematic diagram of a battery provided in some embodiments of the present application;

[0058] FIG13 is a schematic cross-sectional view of a battery provided in some embodiments of the present application;

[0059] FIG14 is an enlarged schematic diagram of the frame in FIG13;

[0060] FIG15 is an enlarged schematic diagram of the circle frame of FIG14 .

[0061] In the accompanying drawings, the drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] The term "plurality" used in this application refers to two or more (including two).

[0069] In the embodiment of the present application, the battery cell may be a secondary battery. A secondary battery refers to a battery cell that can be continuously used by activating active materials by charging after the battery cell is discharged.

[0070] The battery cells can be lithium-ion batteries, sodium-ion batteries, sodium-lithium-ion batteries, lithium metal batteries, sodium metal batteries, lithium-sulfur batteries, magnesium-ion batteries, nickel-hydrogen batteries, nickel-cadmium batteries, lead-acid batteries, etc., which are not limited in the embodiments of the present application.

[0071] A battery cell typically includes an electrode assembly. This assembly includes a positive electrode, a negative electrode, and a separator. 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. The separator, placed between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing the active ions to pass through.

[0072] 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.

[0073] 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.

[0074] 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.).

[0075] 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 may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing phosphates may include but are not limited to lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (such as

[0076] LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, 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 / 3Mn 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

[0077] 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.

[0078] In some embodiments, a positive electrode may be a metal foam. The metal foam may be nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam, among others. When a 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.

[0079] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0080] 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.).

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0086] In some embodiments, the separator is a separator. The present application has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical and mechanical stability can be selected.

[0087] As an 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, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. 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.

[0088] 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.

[0089] In some embodiments, the battery cell also includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, and the electrolyte can be selected based on needs. The electrolyte can be liquid, gel, or solid.

[0090] The liquid electrolyte includes an electrolyte salt and a solvent.

[0091] 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.

[0092] 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.

[0093] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0094] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0095] 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.

[0096] 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.

[0097] As an example, a composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0098] 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.

[0099] In some embodiments, the electrode assembly is a laminate structure.

[0100] 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.

[0101] 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.

[0102] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of stacked folded segments.

[0103] 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.

[0104] 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.

[0105] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0106] 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.

[0107] 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.

[0108] As an example, the battery cell can 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, and a polygonal battery. The polygonal battery is, for example, a hexagonal battery, etc. There is no special limitation in this application.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] In some embodiments, the battery may be an energy storage device, including an energy storage container, an energy storage cabinet, and the like.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] Batteries typically contain multiple cells. If a cell experiences thermal runaway, the high-temperature substances (such as hot gases or particles) inside the cell are released after the pressure relief mechanism is activated. When the released high-temperature gases flow through normal cells, they may heat the pressure relief mechanisms of these cells, causing them to crack and fail, potentially leading to cell failure or thermal runaway, and thus affecting battery reliability.

[0121] In view of this, an embodiment of the present application provides a technical solution, which covers the outer side of the pressure relief mechanism with a protective component with a higher melting point to separate at least part of the high-temperature material from the pressure relief mechanism, reduce the heat conducted to the pressure relief mechanism, reduce the risk of cracking and failure of the pressure relief mechanism, and improve the reliability of the battery cell.

[0122] The battery cells described in the embodiments of the present application are suitable for use in batteries and electrical devices using the batteries.

[0123] 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.

[0124] For the convenience of description, the following embodiments are described by taking a vehicle as an example of an electrical device.

[0125] FIG1 is a schematic structural diagram of a vehicle provided in some embodiments of the present application.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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 .

[0130] 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.

[0131] 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.

[0132] 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.

[0133] 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.

[0134] Figure 3 is an exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 4 is a cross-sectional schematic diagram of a battery cell provided in some embodiments of the present application; Figure 5 is an enlarged schematic diagram of Figure 4 at the circular frame; Figure 6 is an enlarged schematic diagram of Figure 5 at the square frame; Figure 7 is an enlarged schematic diagram of Figure 6 at the circular frame.

[0135] 3 to 7 , an embodiment of the present application provides a battery cell 6 , which includes a housing 20 , an electrode assembly 10 , and other functional components (such as an electrode terminal 30 disposed in the housing 20 ), with at least a portion of the electrode assembly 10 housed in the housing 20 .

[0136] 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.

[0137] 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.

[0138] The housing 21 is a component used to cooperate 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.

[0139] 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 .

[0140] 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, etc., and the present embodiment does not impose any particular limitation on this.

[0141] 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.

[0142] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0143] 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.

[0144] The electrode terminal 30 may be used to electrically connect to the electrode assembly 10 to output or input electrical energy of the battery cell 6 .

[0145] 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.

[0146] 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. The tabs may include a positive tab and a negative tab. The positive and negative tabs may be located together at one end of the main body or separately at opposite ends of the main body.

[0147] During the charge and discharge process of the battery 2 , 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.

[0148] In some embodiments, the battery cell 6 includes a housing 20 and a pressure relief mechanism 40. The housing 20 includes a wall portion.

[0149] 211 , the pressure relief mechanism 40 is provided on the wall portion 211 . The pressure relief mechanism 40 can be actuated to release the gas in the housing 20 when the internal pressure or temperature of the battery cell 6 reaches a threshold.

[0150] As an example, the wall portion 211 may be the end cover 22 or a wall of the housing 21 .

[0151] As an example, the shape of the wall portion 211 may be circular, rectangular, oval, or other shapes.

[0152] In some examples, the pressure relief mechanism 40 and the wall portion 211 are independently formed components and can be connected by welding, bonding, or other methods. For example, the wall portion 211 is provided with a pressure relief hole that passes through the wall portion 211. The pressure relief mechanism 40 is mounted on the wall portion 211 and covers the pressure relief hole, thereby separating the space inside and outside the wall portion 211. In alternative embodiments, the pressure relief mechanism 40 and the wall portion 211 can also be an integrally formed structure.

[0153] The threshold value may be designed to vary depending on the design requirements and may depend on the material of one or more of the positive electrode, negative electrode, electrolyte and separator in the battery cell 6 .

[0154] 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.

[0155] 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 .

[0156] 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 .

[0157] For example, when a battery cell 6 experiences thermal runaway, the continued 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 vent channel, connecting the interior of the housing 20 with the exterior. Gas within the housing 20 can be discharged through the vent channel, thereby reducing the risk of explosion of the battery cell 6.

[0158] 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 vent channel, thereby connecting the interior of the housing 20 with the exterior. Gas inside the housing 20 can be discharged through the vent channel, thereby reducing the risk of explosion of the battery cell 6.

[0159] In some embodiments, the battery cell 6 further includes a protective member 50 , and the melting point of the protective member 50 is greater than or equal to 300° C. In the thickness direction Z of the wall portion 211 , the protective member 50 covers at least a portion of the pressure relief mechanism 40 .

[0160] 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 300°C, 500°C, 700°C, 900°C, 1000°C, 1500°C, 2000°C, or 2500°C.

[0161] In the thickness direction Z of the wall portion 211 , at least a portion of the protection member 50 is located on the side of the pressure relief mechanism 40 facing away from the electrode assembly 10 . In the thickness direction Z of the wall portion 211 , the projection of the protection member 50 at least partially overlaps with the projection of the pressure relief mechanism 40 .

[0162] In the thickness direction Z, the protective member 50 may completely cover the pressure relief mechanism 40 or may only cover a portion of the pressure relief mechanism 40 .

[0163] In the thickness direction Z, 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.

[0164] The protective member 50 may be connected to the wall portion 211 , or may be connected to the pressure relief mechanism 40 .

[0165] 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 action of the internal pressure of the battery cell 6 to reduce the barrier of the protective member 50 to gas.

[0166] When thermal runaway occurs in the battery cell 6, the pressure relief mechanism 40 is actuated and the gas in the outer shell 20 is released outward to reduce the risk of explosion or fire of the battery cell 6 and improve the reliability of the battery cell 6. The protective component 50 can isolate external impurities (such as dust, particles, etc.), reduce the corrosion or damage of the impurities to the pressure relief mechanism 40, and improve the reliability of the pressure relief mechanism 40. The melting point of the protective component 50 is greater than or equal to 300°C and can withstand high thermal shock. When high-temperature substances (such as high-temperature gases released by other battery cells 6) flow through the battery cell 6, the protective component 50 can withstand the thermal shock of the high-temperature substances and is not prone to deformation, melting through, and other problems under high temperature. Therefore, at least part of the high-temperature substances are separated from the pressure relief mechanism 40, reducing the heat conducted to the pressure relief mechanism 40, reducing the risk of cracking and failure of the pressure relief mechanism 40, and improving the reliability of the battery cell 6.

[0167] In some embodiments, the pressure relief mechanism 40 is provided with a weak portion 41. The weak portion 41 is a portion of the pressure relief mechanism 40 having relatively low strength and is easily broken, shattered, torn, or opened. For example, 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.

[0168] In some examples, the present application may provide grooves, notches, through-holes, or other structures 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 region serves as the weak portion 41.

[0169] The weak portion 41 can rupture when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the gas within the outer case 20 .

[0170] In some embodiments, the pressure relief mechanism 40 and the wall portion 211 are independently formed components and can be connected by welding. In other embodiments, the pressure relief mechanism 40 and the wall portion 211 are integrally formed components, and the pressure relief mechanism 40 includes a weak portion 41 and an area surrounded by the weak portion 41.

[0171] In some embodiments, the protective member 50 covers the weak portion 41 in the thickness direction Z. In the thickness direction Z, the protective member 50 may cover a portion of the weak portion 41 or may completely cover the weak portion 41.

[0172] The protective member 50 can reduce the risk of high-temperature substances directly impacting the weak portion 41 , reduce the thermal shock to the weak portion 41 , reduce the risk of cracking and failure of the weak portion 41 , and improve the reliability of the battery cell 6 .

[0173] Optionally, in the thickness direction Z, the protective member 50 completely covers the weak portion 41 .

[0174] In some embodiments, in any direction perpendicular to the thickness direction Z, the size of the protective member 50 is greater than or equal to the size of the pressure relief mechanism 40 , such that the protective member 50 completely covers the pressure relief mechanism 40 .

[0175] In some embodiments, the wall portion 211 has an outer surface 212 , and the wall portion 211 defines a receiving recess 213 that is recessed relative to the outer surface 212 .

[0176] The outer surface 212 may be a surface of the wall portion 211 facing away from the electrode assembly 10. Alternatively, the outer surface 212 may be a plane.

[0177] As an example, the shape of the receiving recess 213 may be columnar, conical, stepped, or other shapes.

[0178] In some embodiments, at least a portion of the protective member 50 is received in the receiving recess 213. The protective member 50 may be entirely received in the receiving recess 213, or only partially received in the receiving recess 213.

[0179] By providing the accommodating recess 213 and disposing at least a portion of the protective member 50 in the accommodating recess 213 , the space occupied by the battery cell 6 in the thickness direction Z can be reduced, thereby improving the space utilization and energy density of the battery cell 6 .

[0180] In some embodiments, the protective member 50 is completely accommodated in the accommodating recess 213. In the thickness direction Z, the surface of the protective member 50 facing away from the pressure relief mechanism 40 does not extend beyond the outer surface 212.

[0181] The present embodiment can further improve the space utilization and energy density of the battery cell 6. Furthermore, completely accommodating the protective member 50 within the accommodating recess 213 can reduce the risk of friction between the protective member 50 and external structures during the production, transportation, and use of the battery cell 6, thereby improving the reliability of the protective member 50.

[0182] In some embodiments, a through hole 215 is defined in the bottom wall 214 of the accommodating recess 213 . The pressure relief mechanism 40 is accommodated in the accommodating recess 213 , connected to the bottom wall 214 , and covers the through hole 215 .

[0183] When the pressure relief mechanism 40 is activated, a venting channel is formed, and the gas in the housing 20 can be discharged to the outside of the battery cell 6 through the through hole 215 and the venting channel.

[0184] In some embodiments, in the thickness direction Z, the protective member 50 is spaced apart from the pressure relief mechanism 40 .

[0185] The embodiment of the present application can reduce the heat transfer rate between the protective component 50 and the pressure relief mechanism 40 when the protective component 50 is subjected to thermal shock from high-temperature materials, reduce the temperature rise of the pressure relief mechanism 40, and reduce the risk of cracking and failure of the pressure relief mechanism 40.

[0186] In some embodiments, the accommodating recess 213 is stepped, and a step surface 213 a is provided on a side wall of the accommodating recess 213 . The protective member 50 is connected to the step surface 213 a , thereby being spaced apart from the pressure relief mechanism 40 .

[0187] In some embodiments, in the thickness direction Z, there are no other components between the protective member 50 and the pressure relief mechanism 40 .

[0188] In the embodiment of the present application, a heat-insulating cavity is formed between the protective member 50 and the pressure relief mechanism 40 to reduce the heat transfer rate between the protective member 50 and the pressure relief mechanism 40. The absence of any other physical components between the protective member 50 and the pressure relief mechanism 40 not only reduces gas obstruction when the pressure relief mechanism 40 is actuated, but also, to a certain extent, prevents heat transfer from the physical structure between the protective member 50 and the pressure relief mechanism 40, thereby reducing the heat transfer rate between the protective member 50 and the pressure relief mechanism 40.

[0189] In some embodiments, in the thickness direction Z, the minimum distance between the protective member 50 and the pressure relief mechanism 40 is D, and the minimum thickness of the protective member 50 is t. D and t satisfy: t×D≥0.01mm 2 .

[0190] The larger t is, the lower the temperature of the surface of the protective member 50 facing the pressure relief mechanism 40 is when a high-temperature substance impacts the protective member 50, and the less heat the protective member 50 radiates toward the pressure relief mechanism 40. The smaller t is, the higher the temperature of the surface of the protective member 50 facing the pressure relief mechanism 40 is when a high-temperature substance impacts the protective member 50, and the more heat the protective member 50 radiates toward the pressure relief mechanism 40.

[0191] The larger D is, the longer the heat transfer path between the protective member 50 and the pressure relief mechanism 40 is when high-temperature material impacts the protective member 50 ; the smaller D is, the shorter the heat transfer path between the protective member 50 and the pressure relief mechanism 40 is.

[0192] In the embodiment of the present application, t×D is defined as greater than or equal to 0.01 mm. 2 , when high-temperature materials impact the protective component 50 , the temperature rise of the pressure relief mechanism 40 can be reduced, thereby reducing the risk of cracking and failure of the pressure relief mechanism 40 .

[0193] As an example, t×D is 0.01 mm 2 , 0.03mm 2 , 0.05mm 2 , 0.08mm 2 , 0.1mm 2 , 0.15mm 2 , 0.3mm 2 , 0.5mm 2 , 0.8mm 2 or 1mm 2 .

[0194] Optionally, t×D≥0.05mm 2 . Further optionally, t×D≥0.1mm 2 .

[0195] In some embodiments, t is 0.05 mm-0.4 mm.

[0196] In this embodiment of the present application, t is limited to greater than or equal to 0.05 mm. This reduces the heat radiated from the protective member 50 to the pressure relief mechanism 40 when a high-temperature object impacts the protective member 50, thereby lowering the temperature rise of the pressure relief mechanism 40. A larger t increases the space and weight occupied by the protective member 50. Limiting t to less than or equal to 0.4 mm reduces the space and weight occupied by the protective member 50, while ensuring that the protective requirements of the protective member 50 are met, thereby increasing the energy density of the battery cell 6.

[0197] Optionally, t is 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.3 mm, 0.32 mm, 0.35 mm or 0.4 mm.

[0198] In some embodiments, t is 0.08 mm-0.2 mm, so as to reduce the space and weight occupied by the protective member 50 and improve the energy density of the battery cell 6 while the protection requirements of the protective member 50 meet the needs.

[0199] In some embodiments, the melting point of the protective member 50 is greater than or equal to 500° C. The protective member 50 has a high melting point and is not easily melted when subjected to thermal shock, thereby having good thermal shock resistance and reducing the risk of the protective member 50 being melted through.

[0200] In some embodiments, the melting point of the protective member 50 is greater than or equal to 1000°C.

[0201] In some embodiments, the material of the protective member 50 includes mica, rubber, ceramic, or polyimide.

[0202] Mica, rubber, ceramics and polyimide have good thermal shock resistance, thereby providing protection for the pressure relief mechanism 40 and reducing the risk of failure and cracking of the pressure relief mechanism 40.

[0203] In some embodiments, the material of the protective member 50 includes polyimide, and the tensile strength of the protective member 50 at 150° C. is 100 MPa-350 MPa.

[0204] For example, using a film tensile strength tester, at an ambient temperature of 150°C, a gradually increasing tensile load is applied along the length of a standard specimen, causing it to deform until it breaks. The maximum tensile stress required to break the specimen is the tensile strength. Tensile strength is also known as ultimate tensile strength.

[0205] The greater the tensile strength of the protective member 50, the more difficult it is to rupture when the pressure relief mechanism 40 is activated. In this embodiment of the application, the tensile strength of the protective member 50 at 150°C is set to be less than or equal to 350 MPa, which can ensure that the protective member 50 ruptures promptly when the pressure relief mechanism 40 is activated, thereby improving exhaust efficiency.

[0206] The lower the tensile strength of the protective member 50, the greater its deformation during external pressure fluctuations. Over time, the protective member 50 is more susceptible to fatigue deformation. In this embodiment, the tensile strength of the protective member 50 at 150°C is set to be greater than or equal to 100 MPa, which can slow down the aging of the protective member and extend the service life of the battery cell 6.

[0207] Optionally, the tensile strength of the protective member 50 at 150° C. is 100 MPa, 120 MPa, 150 MPa, 170 MPa, 200 MPa, 220 MPa, 250 MPa, 270 MPa, 300 MPa, 320 MPa, or 350 MPa.

[0208] In some embodiments, the protective member 50 has a tensile strength of 170 MPa to 250 MPa at 150°C.

[0209] In some embodiments, the housing 20 includes a shell 21 and an end cover 22 . The shell 21 has an opening at one end. The end cover 22 is connected to the shell 21 and covers the opening.

[0210] 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.

[0211] In some embodiments, the housing 21 includes a wall portion 211 that is opposite to the end cap 22. Disposing the pressure relief mechanism 40 on the housing 21 can reserve more installation space for components on the end cap 22, for example, more installation space can be reserved for the electrode terminal 30.

[0212] In some embodiments, a thickness direction Z of the wall portion 211 is parallel to the direction of gravity, and the wall portion 211 is located at a lower side of the electrode assembly 10 in the direction of gravity.

[0213] The wall portion 211 can provide support for the electrode assembly 10 and improve the stability of the electrode assembly 10. When the battery cell 6 is in thermal runaway, gas can be ejected downward, thereby reducing exhaust resistance and improving exhaust efficiency.

[0214] In some embodiments, the protective member 50 is connected to the wall portion 211 to improve the stability of the protective member 50 and reduce the risk of the protective member 50 falling off.

[0215] FIG8 is an enlarged schematic diagram of the circle frame of FIG5 ; FIG9 is a top view of the protective component and the connection layer of the battery cell provided in some embodiments of the present application.

[0216] Please refer to FIG. 6 to FIG. 9 . In some embodiments, the battery cell 6 further includes a connection layer 60 , and the protective member 50 is connected to the wall portion 211 through the connection layer 60 .

[0217] The connecting layer 60 can be connected to the wall portion 211 and the protective member 50 in a variety of ways. In some examples, the connecting layer 60 can adhere the protective member 50 to the wall portion 211. In other examples, the connecting layer 60 can be welded to the protective member 50 and the wall portion 211.

[0218] In some embodiments, the connection layer 60 can be actuated to release at least a portion of the guard member 50 from the wall portion 211 when the internal pressure or temperature of the battery cell 6 reaches a threshold value.

[0219] When the internal pressure or temperature of the battery cell 6 reaches a threshold value, the protective member 50 may be separated from the wall portion 211 in its entirety or only partially.

[0220] At least a portion of the protective member 50 is separated from the wall portion 211 , which may mean that at least a portion of the protective member 50 is no longer constrained by the wall portion 211 and can deviate from an initially set position.

[0221] "Actuation of the connection layer 60" means that the connection layer 60 is moved or activated to a certain state, thereby causing at least a portion of the protective member 50 to separate from the wall portion 211. The movement of the connection layer 60 may include, but is not limited to: at least a portion of the connection layer 60 is disconnected from the wall portion 211, at least a portion of the connection layer 60 is disconnected from the protective member 50, the connection layer 60 is torn, and the like.

[0222] When the internal pressure or temperature of the battery cell 6 reaches a threshold, the pressure relief mechanism 40 is actuated to release the gas in the outer shell 20. Under the action of other internal factors, at least part of the protective member 50 is separated from the wall 211, thereby releasing the internal gas of the battery cell 6 and reducing the internal pressure and temperature of the battery cell 6.

[0223] In some embodiments, the connecting layer 60 can be activated when the internal pressure or temperature of the battery cell 6 reaches a threshold value, allowing the entire protective member 50 to separate from the wall portion 211. When a short circuit, overcharge, or other phenomena occur, the pressure relief mechanism 40 is activated, and the protective member 50 can be separated from the wall portion 211 and no longer block the pressure relief mechanism 40, thereby increasing the gas release rate and reducing the risk of battery cell 6 explosion.

[0224] In other embodiments, the protective member 50 may also be ruptured when the internal pressure or temperature of the battery cell 6 reaches a threshold value, thereby releasing the gas within the housing 20 .

[0225] In some embodiments, the connecting layer 60 includes a glue layer.

[0226] As an example, the adhesive layer includes at least one of epoxy resin structural adhesive, acrylate structural adhesive, polyimide structural adhesive, maleimide structural adhesive, polyurethane structural adhesive and acrylic structural adhesive.

[0227] When the battery cell 6 experiences thermal runaway, heat can be transferred to the connecting layer 60 , causing the connecting layer 60 to soften, thereby enabling the protective member 50 to be separated from the wall portion 211 in a timely manner when the pressure relief mechanism 40 is actuated.

[0228] In some embodiments, the connection layer 60 is disposed on the outer peripheral area of ​​the surface of the protective member 50 facing the pressure relief mechanism 40 .

[0229] Disposing the connection layer 60 in the peripheral area of ​​the protective component 50 can save the amount of the connection layer 60 and reduce the risk of connection between the connection layer 60 and the pressure relief mechanism 40.

[0230] In some embodiments, in the thickness direction Z, the entire connection layer 60 is located between the wall portion 211 and the protection member 50 .

[0231] In some embodiments, an escape space 70 is formed between the protective component 50 and the pressure relief mechanism 40 , and a connecting channel 80 is provided between the protective component 50 and the wall portion 211 . One end of the connecting channel 80 is connected to the outside, and the other end is connected to the escape space 70 .

[0232] During the charge and discharge process of the battery cell 6, the internal pressure of the battery cell 6 may fluctuate slightly. When the internal pressure of the battery cell 6 fluctuates, the pressure relief mechanism 40 may bulge outward. In this embodiment of the present application, by providing a connecting flow channel 80 to connect the escape space 70 with the external environment, the pressure fluctuation in the escape space 70 when the pressure relief mechanism 40 bulges is reduced, thereby reducing deformation of the protective member 50.

[0233] In addition, during the production process of the battery cell 6 , the airtightness of the pressure relief mechanism 40 can also be tested through the connecting flow channel 80 and the escape space 70 .

[0234] In some embodiments, when the connection layer 60 is provided, the connection layer 60 may be left open, so that the connection layer 60 , the wall portion 211 and the protective member 50 form a connecting flow channel 80 .

[0235] FIG10 is a top view of a protective member and a connecting layer of a battery cell provided in some other embodiments of the present application; FIG11 is a schematic cross-sectional view of the protective member and the connecting layer shown in FIG10 .

[0236] As shown in FIG. 10 and FIG. 11 , in some embodiments, the communication flow passage 80 includes a groove 51 provided on a surface of the protective member 50 facing the pressure relief mechanism 40 .

[0237] A groove 51 is formed on the surface of the pressure relief mechanism 40 to connect the escape space 70 with the external environment of the battery cell 6 .

[0238] In some embodiments, the connection layer 60 and the groove 51 do not overlap in the thickness direction Z, so as to reduce the risk of the connection layer 60 filling into the groove 51 .

[0239] Figure 12 is a schematic diagram of a battery provided in some embodiments of the present application; Figure 13 is a cross-sectional schematic diagram of a battery provided in some embodiments of the present application; Figure 14 is an enlarged schematic diagram of the square frame of Figure 13; and Figure 15 is an enlarged schematic diagram of the circular frame of Figure 14.

[0240] 12 to 15 , an embodiment of the present application further provides a battery 2 , which includes a plurality of battery cells 6 provided by any of the aforementioned embodiments.

[0241] In some embodiments, the battery 2 further includes a housing 5, which houses multiple battery cells 6. The housing 5 includes a first wall 5d, with a wall portion 211 disposed at one end of the housing 20 facing the first wall 5d. A channel 5e is defined within the inner side of the first wall 5d. In the thickness direction Z, the projection of the pressure relief mechanism 40 of the multiple battery cells 6 is located within the projection of the channel 5e. In the thickness direction Z, the protective member 50 is located between the channel 5e and the pressure relief mechanism 40.

[0242] When a battery cell 6 experiences thermal runaway, the pressure relief mechanism 40 activates and releases the gas within the housing 20 into the channel 5e. The channel 5e guides the high-temperature gas flow and discharges it outside the housing 5, reducing the risk of explosion of the battery 2. As the high-temperature gas flows through the channel 5e, the protective member 50 isolates the high-temperature gas from the pressure relief mechanism 40, reducing the amount of heat transferred to the pressure relief mechanism 40 and the risk of cracking and failure of the pressure relief mechanism 40. This simplifies the progression of thermal runaway and improves the reliability of the battery 2.

[0243] In some embodiments, the projection of the protective member 50 is located within the projection of the channel 5e in the thickness direction Z. When the pressure relief mechanism 40 is actuated, the protective member 50 can enter the channel 5e to release gas within the housing 20. This embodiment of the present application reduces the risk of interference with the protective member 50 by the first wall 5d, allowing the protective member 50 to smoothly enter the channel 5e.

[0244] In some embodiments, in any direction perpendicular to the thickness direction Z, the size of the channel 5 e is greater than the size of the protective member 50 .

[0245] Exemplarily, in the length direction X of the wall portion 211 , the size of the channel 5 e is larger than the size of the protective member 50 ; in the width direction Y of the wall portion 211 , the size of the channel 5 e is larger than the size of the protective member 50 .

[0246] The embodiment of the present application can reduce the problem of the first box wall 5 d interfering with the protective member 50 due to assembly errors, so that the protective member 50 can smoothly enter the channel 5 e when the battery cell 6 thermally runs away.

[0247] According to some embodiments of the present application, the present application further provides an electrical device, comprising the battery 2 of any of the above embodiments, the battery 2 being used to provide power to the electrical device. The electrical device may be any of the aforementioned devices or systems using the battery 2.

[0248] 3 to 8 , an embodiment of the present application provides a battery cell 6 , which includes a housing 20 , an electrode assembly 10 , a pressure relief mechanism 40 , a protective member 50 , and a connecting layer 60 .

[0249] The electrode assembly 10 is housed in a housing 20 .

[0250] The outer shell 20 includes a shell 21 and an end cap 22. The shell 21 has an opening at one end, and the end cap 22 is connected to the shell 21 and covers the opening. The shell 21 includes a wall portion 211, which is opposite to the end cap 22. The thickness direction Z of the wall portion 211 is parallel to the direction of gravity, and the wall portion 211 is located on the lower side of the electrode assembly 10 in the direction of gravity.

[0251] The wall portion 211 has an outer surface 212 on a side facing away from the electrode assembly 10, and is provided with a receiving recess 213 that is recessed relative to the outer surface 212. A through hole 215 is provided on a bottom wall 214 of the receiving recess 213. The pressure relief mechanism 40 is received in the receiving recess 213, connected to the bottom wall 214, and covers the through hole 215.

[0252] The protective member 50 is entirely accommodated in the accommodation recess 213 and is located on the side of the pressure relief mechanism 40 away from the electrode assembly 10. In the thickness direction Z, the protective member 50 is spaced apart from the pressure relief mechanism 40 and completely covers the pressure relief mechanism 40.

[0253] A step surface 213 a is provided on the side wall of the accommodating recess 213 . The connecting layer 60 is located between the step surface 213 a and the protection member 50 to connect the protection member 50 to the wall portion 211 .

[0254] The pressure relief mechanism 40 can be activated to release gas in the housing 20 when the internal pressure or temperature of the battery cell 6 reaches a threshold value. The connection layer 60 can be activated to separate the protective member 50 from the wall portion 211 when the internal pressure or temperature of the battery cell 6 reaches a threshold value.

[0255] The melting point of the protective member 50 is greater than 500° C. Optionally, the protective member 50 is a mica board.

[0256] 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; a pressure relief mechanism, disposed on the wall portion, the pressure relief mechanism being actuated to release gas in the housing when the internal pressure or temperature of the battery cell reaches a threshold; as well as A protective member having a melting point greater than or equal to 300° C., and covering at least a portion of the pressure relief mechanism in a thickness direction of the wall portion.

2. The battery cell according to claim 1, wherein: The wall portion has an outer surface, and the wall portion is provided with a receiving recessed portion recessed relative to the outer surface; At least a portion of the protection member is accommodated in the accommodation recess.

3. The battery cell according to claim 2, wherein: The protection member is completely accommodated in the accommodation recess.

4. The battery cell according to claim 2 or 3, wherein: The bottom wall of the accommodating recess is provided with a through hole, and the pressure relief mechanism is accommodated in the accommodating recess, connected to the bottom wall and covers the through hole; In the thickness direction, the protection member is spaced apart from the pressure relief mechanism.

5. The battery cell according to claim 4, wherein: In the thickness direction, there are no other components between the protective component and the pressure relief mechanism.

6. The battery cell according to claim 4 or 5, wherein: In the thickness direction, the minimum distance between the protective component and the pressure relief mechanism is D, and the minimum thickness of the protective component is t; D and t satisfy: t×D≥0.01mm 2 .

7. The battery cell according to claim 6, wherein: t is 0.05mm-0.4mm.

8. The battery cell according to claim 7, wherein: t is 0.08mm-0.2mm.

9. The battery cell according to any one of claims 1 to 8, further comprising a connection layer, wherein the protective member is connected to the wall portion through the connection layer; The connecting layer is actuatable when the internal pressure or temperature of the battery cell reaches a threshold value to release at least a portion of the guard member from the wall portion.

10. The battery cell according to claim 9, wherein: The connecting layer includes an adhesive layer.

11. The battery cell according to claim 9 or 10, wherein: The connection layer is disposed on an outer peripheral region of a surface of the protective component facing the pressure relief mechanism.

12. The battery cell according to claims 9 to 11, wherein: An escape space is formed between the protective component and the pressure relief mechanism, and a communication channel is provided between the protective component and the wall portion. One end of the communication channel is communicated with the outside, and the other end is communicated with the escape space.

13. The battery cell according to claim 12, wherein: The communication flow passage includes a groove provided on a surface of the protection member facing the pressure relief mechanism.

14. The battery cell according to any one of claims 1 to 13, wherein: The melting point of the protective member is greater than or equal to 500°C.

15. The battery cell according to any one of claims 1 to 14, wherein: The material of the protective component includes one of mica, rubber, ceramic or polyimide.

16. The battery cell according to any one of claims 1 to 15, wherein: The material of the protective component includes polyimide, and the tensile strength of the protective component at 150° C. is 100 MPa-350 MPa.

17. The battery cell according to any one of claims 1 to 16, further comprising an electrode assembly housed in the housing; The thickness direction of the wall portion is parallel to the gravity direction, and the wall portion is located at a lower side of the electrode assembly in the gravity direction.

18. The battery cell according to any one of claims 1 to 17, wherein: The housing comprises a shell and an end cover, one end of the shell has an opening, the end cover is connected to the shell and covers the opening; the shell comprises the wall portion, and the wall portion is opposite to the end cover.

19. A battery comprising a plurality of battery cells according to any one of claims 1 to 18.

20. The battery according to claim 19, further comprising a housing, wherein the plurality of battery cells are accommodated in the housing; The box body comprises a first box wall, and the wall portion is arranged at one end of the shell facing the first box wall; A channel is provided on the inner side of the first box wall; in the thickness direction, the projections of the pressure relief mechanisms of the plurality of battery cells are located within the projection of the channel; In the thickness direction, the protection member is located between the channel and the pressure relief mechanism.

21. The battery according to claim 20, wherein In the thickness direction, a projection of the guard member is located within a projection of the channel.

22. The battery according to claim 21, wherein In any direction perpendicular to the thickness direction, a size of the channel is larger than a size of the guard member.

23. An electrical device comprising a battery according to any one of claims 19 to 22, wherein the battery is used to provide electrical energy.

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