Battery cells, batteries and electrical devices

Abstract

This application discloses a battery cell, a battery, and an electrical device. The battery cell includes a casing, a pressure relief mechanism, and a protective member. The casing includes a wall. The pressure relief mechanism is disposed in the wall and is actuated when the internal pressure or temperature of the battery cell reaches a threshold to release gas within the casing. 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 in the thickness direction of the wall.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application 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] This application relates to the field of batteries, and in particular to a battery cell, a battery, and an electrical device. Background Technology

[0004] With the development of battery technology, battery cells are being applied in more and more fields, gradually replacing traditional fossil fuels in the automotive power sector. Battery cells can store chemical energy and controllably convert it into electrical energy. In recyclable battery cells, the active materials can be reactivated through charging after discharge, allowing for continued use.

[0005] Improving the reliability of individual battery cells is an important research direction in the industry. Utility Model Content

[0006] This application provides a battery cell, a battery, and an electrical device that can improve the reliability of the battery cell.

[0007] In a first aspect, this application provides a battery cell including a casing, a pressure relief mechanism, and a protective member. The casing includes a wall portion. The pressure relief mechanism is disposed in the wall portion and is actuated when the internal pressure or temperature of the battery cell reaches a threshold value to release gas within the casing. The protective member has a melting point greater than or equal to 300°C, and in the thickness direction of the wall portion, the protective member covers at least a portion of the pressure relief mechanism.

[0008] When a battery cell experiences thermal runaway, the pressure relief mechanism is activated and releases gas from the casing to reduce the risk of explosion and fire, thus improving the reliability of the battery cell. The protective components isolate external impurities, reducing corrosion or damage to the pressure relief mechanism and improving its reliability. With a melting point greater than or equal to 300°C, the protective components can withstand high thermal shock. When high-temperature substances flow through the battery cell, the protective components can withstand the thermal shock and are less prone to deformation or melting under high temperatures. This effectively isolates at least a portion of the high-temperature substances from the pressure relief mechanism, reducing heat conduction to the mechanism, lowering the risk of cracking and failure, and improving the reliability of the battery cell.

[0009] In some embodiments, the wall portion has an outer surface and a receiving recess recessed relative to the outer surface. At least a portion of the protective member is received in the receiving recess.

[0010] By creating a recessed area and placing at least a portion of the protective component within the recessed area, 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.

[0011] In some embodiments, the protective member is fully accommodated within the receiving recess.

[0012] The embodiments of this application can further improve the space utilization and energy density of battery cells. In addition, by completely accommodating the protective component within the receiving recess, the risk of friction between the protective component and external structures can be reduced during the production, transportation, and use of the battery cell, thereby improving the reliability of the protective component.

[0013] In some embodiments, the bottom wall of the receiving recess has a through hole, and the pressure relief mechanism is received in the receiving recess, connected to the bottom wall, and covers the through hole. In the thickness direction, the protective member and the pressure relief mechanism are spaced apart. This embodiment 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 a high-temperature substance, thereby reducing the temperature rise of the pressure relief mechanism and lowering the risk of cracking and failure.

[0014] In some embodiments, there are no other components between the protective member and the pressure relief mechanism in the thickness direction.

[0015] A heat-insulating cavity is formed between the protective component and the pressure relief mechanism to reduce the heat transfer rate between them. No other solid components are placed between the protective component and the pressure relief mechanism. This reduces obstruction to the gas when the pressure relief mechanism is actuated and also prevents heat conduction by solid structures between them, further reducing the heat transfer rate.

[0016] In some embodiments, the minimum distance between the protective member and the pressure relief mechanism in the thickness direction is D, and the minimum thickness of the protective member is t. D and t satisfy: t × D ≥ 0.01 mm 2 .

[0017] The larger the value of t, the lower the temperature of the surface of the protective component facing the pressure relief mechanism when a high-temperature substance impacts the protective component, and the less heat the protective component radiates towards the pressure relief mechanism. The smaller the value of t, the higher the temperature of the surface of the protective component facing the pressure relief mechanism, and the more heat the protective component radiates towards the pressure relief mechanism. The larger the value of D, the longer the heat transfer path between the protective component and the pressure relief mechanism when a high-temperature substance impacts the protective component; the smaller the value of D, the shorter the heat transfer path between the protective component and the pressure relief mechanism.

[0018] In this embodiment, t×D is defined as greater than or equal to 0.01 mm. 2It can reduce the temperature rise of the pressure relief mechanism when high-temperature materials impact the protective components, thereby reducing the risk of cracking and failure of the pressure relief mechanism.

[0019] In some embodiments, t is 0.05mm-0.4mm. Limiting t to greater than or equal to 0.05mm can reduce the heat radiated from the protective component to the pressure relief mechanism when subjected to impact from high-temperature substances, thereby reducing the temperature rise of the pressure relief mechanism. The larger t is, the greater the space and weight occupied by the protective component; limiting t to less than or equal to 0.4mm can reduce the space and weight occupied by the protective component while meeting the protection requirements, thereby increasing the energy density of the battery cells.

[0020] In some embodiments, t is 0.08mm-0.2mm, 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.

[0021] In some embodiments, the battery cell further includes a connecting layer through which the protective member is connected to the wall. The connecting layer is actuated when the internal pressure or temperature of the battery cell reaches a threshold, causing at least a portion of the protective member to detach from the wall.

[0022] When the internal pressure or temperature of a battery cell reaches a threshold, the pressure relief mechanism is activated and releases the gas inside the casing. Under the action of other internal forces, at least part of the protective component detaches from the wall, thereby releasing the internal gas of the battery cell and reducing the internal pressure and temperature of the battery cell.

[0023] In some embodiments, the bonding layer includes an adhesive layer.

[0024] When a single battery cell experiences thermal runaway, heat can be conducted to the connecting layer, causing it to soften and allowing the protective components to detach from the wall in a timely manner when the pressure relief mechanism is activated.

[0025] In some embodiments, the connecting layer is disposed on the outer peripheral region of the surface of the protective member facing the pressure relief mechanism. Disposing of the connecting layer on the outer peripheral region of the protective member can save on the amount of connecting layer used and reduce the risk of the connecting layer connecting to the pressure relief mechanism.

[0026] In some embodiments, a clearance space is formed between the protective member and the pressure relief mechanism, and a connecting channel is provided between the protective member and the wall, with one end of the connecting channel communicating with the outside and the other end communicating with the clearance space.

[0027] During the charging and discharging process of a single battery cell, the internal air pressure of the cell fluctuates slightly. When this internal pressure fluctuates, the pressure relief mechanism may bulge outwards. This embodiment addresses this by providing a connecting channel that connects the clearance space to the external environment, reducing pressure changes in the clearance space when the pressure relief mechanism bulges, and minimizing deformation of the protective components. Furthermore, during the battery cell manufacturing process, the airtightness of the pressure relief mechanism can be tested using the connecting channel and the clearance space.

[0028] In some embodiments, the communication channel includes a groove provided on the surface of the protective member facing the pressure relief mechanism. By creating a groove on the surface of the pressure relief mechanism, the clearance space is connected to the external environment of the battery cell.

[0029] In some embodiments, the melting point of the protective component is greater than or equal to 500°C. The high melting point of the protective component makes it less prone to melting under thermal shock, thus providing better thermal shock resistance and reducing the risk of it being melted through.

[0030] In some embodiments, the protective component is made of one 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.

[0031] In some embodiments, the protective component is made of polyimide and has a tensile strength of 100 MPa-350 MPa at 150°C.

[0032] The greater the tensile strength of the protective component, the more difficult it is for it to break when the pressure relief mechanism is activated. In this embodiment, the tensile strength of the protective component at 150°C is set to be less than or equal to 350 MPa, which enables the protective component to break in a timely manner when the pressure relief mechanism is activated, thereby improving exhaust efficiency.

[0033] The lower the tensile strength of the protective component, the greater its deformation under external air pressure fluctuations; and the more time it is used, the more prone it is to fatigue deformation. In this application, the tensile strength of the protective component at 150°C is set to be greater than or equal to 100 MPa, which can slow down the aging of the protective component and extend the service life of the battery cells.

[0034] In some embodiments, the battery cell further includes an electrode assembly housed within a casing. The thickness direction of the wall is parallel to the direction of gravity, and the wall is located below the electrode assembly in the direction of gravity. The wall can provide support for the electrode assembly, improving its stability. In the event of thermal runaway of the battery cell, gas can be ejected downwards, thereby reducing exhaust resistance and improving exhaust efficiency.

[0035] In some embodiments, the housing includes a housing and an end cap, one end of the housing having an opening, and the end cap being connected to the housing and covering the opening; the housing includes a wall portion opposite to the end cap. Placing the pressure relief mechanism on the housing allows for more installation space for components on the end cap.

[0036] Secondly, embodiments of this application provide a battery comprising a plurality of battery cells according to any of the embodiments of the first aspect.

[0037] In some embodiments, the battery further includes a housing, in which multiple battery cells are housed. The housing includes a first wall, with a wall portion located at the end of the outer casing facing the first wall. A channel is provided on the inner side of the first wall; in the thickness direction, the projection of the pressure relief mechanism of the multiple battery cells lies within the projection of the channel. In the thickness direction, a protective member is located between the channel and the pressure relief mechanism.

[0038] When a battery cell experiences thermal runaway, the pressure relief mechanism is activated, releasing gas from inside the casing into a channel. This channel guides the flow of high-temperature gas, expending it to the outside of the casing and reducing the risk of battery explosion. As the high-temperature gas flows along the channel, protective components isolate it from the pressure relief mechanism, reducing heat transfer to the mechanism, lowering the risk of cracking and failure, simplifying the progression of thermal runaway, and improving battery reliability.

[0039] In some embodiments, the projection of the protective member lies within the projection of the channel in the thickness direction.

[0040] When the pressure relief mechanism is activated, the protective component can enter the channel to release the gas inside the casing; the embodiments of this application can reduce the risk of the first casing wall interfering with the protective component, so that the protective component can smoothly enter the channel.

[0041] In some embodiments, the size of the channel is larger than the size of the protective member in any direction perpendicular to the thickness direction.

[0042] The embodiments of this application can reduce the problem of interference between the first box wall and the protective components caused by assembly errors, so that the protective components can smoothly enter the channel when the battery cell thermally runs away.

[0043] Thirdly, this application provides an electrical device that includes a battery according to any embodiment of the second aspect, the battery being used to provide electrical energy. Attached Figure Description

[0044] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0045] Figure 1 This application provides structural schematic diagrams of vehicles for some embodiments;

[0046] Figure 2 Explosion diagrams of batteries provided for some embodiments of this application;

[0047] Figure 3 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application;

[0048] Figure 4 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application;

[0049] Figure 5 for Figure 4 Enlarged view of the area within the circle;

[0050] Figure 6 for Figure 5 Enlarged illustration within the box;

[0051] Figure 7 for Figure 6 Enlarged view of the area within the circle;

[0052] Figure 8 for Figure 5 Enlarged view of the area within the circle;

[0053] Figure 9 Top view of the protective member and connecting layer of a battery cell provided in some embodiments of this application;

[0054] Figure 10 Top view of the protective member and connecting layer of the battery cell provided in other embodiments of this application;

[0055] Figure 11 for Figure 10 The diagram shows a cross-sectional view of the protective components and connecting layers.

[0056] Figure 12 A schematic diagram of a battery provided for some embodiments of this application;

[0057] Figure 13 A cross-sectional schematic diagram of a battery provided in some embodiments of this application;

[0058] Figure 14 for Figure 13 Enlarged illustration within the box;

[0059] Figure 15 for Figure 14 Enlarged view of the area within the circle.

[0060] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the description of this application is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the description, claims, and accompanying drawings of this application are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the description, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy.

[0063] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0064] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0065] In this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this application, the character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0066] In the embodiments of this application, the same reference numerals denote 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 this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0067] In this application, "multiple" means two or more (including two).

[0068] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0069] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and the embodiments of this application are not limited to this.

[0070] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through.

[0071] 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.

[0072] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the two opposite surfaces of the positive current collector.

[0073] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with a silver surface treatment, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors can 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.).

[0074] As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites. Examples of lithium transition metal oxide 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, and lithium nickel cobalt manganese oxide (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM) 333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.80 Co 0.15 Al 0.05 At least one of O2 and its modified compounds.

[0075] In some embodiments, the positive electrode can be a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When foamed metal is used as the positive electrode, the surface of the foamed metal may or may not contain a positive electrode active material. As an example, lithium source material, potassium metal, or sodium metal may also be filled and / or deposited within the foamed metal, where the lithium source material is lithium metal and / or a lithium-rich material.

[0076] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0077] 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, it can be silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc. Foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. Composite current collectors can include a polymer material base layer and a metal layer. Composite current collectors 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.).

[0078] 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.

[0079] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0080] As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. 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, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0081] In some embodiments, the positive current collector can be made of aluminum, and the negative current collector can be made of copper.

[0082] In some embodiments, the electrode assembly further includes an isolator disposed between the positive and negative electrodes.

[0083] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected.

[0084] 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, 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 located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes.

[0085] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0086] 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 impose specific limitations on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0087] Liquid electrolytes include electrolyte salts and solvents.

[0088] 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 difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0089] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may 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, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0090] Among them, the gel electrolyte includes a polymer as the electrolyte backbone network, combined with an ionic liquid - lithium salt.

[0091] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0092] As an example, polymer solid electrolytes can be polyether (polyoxyethylene), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids-lithium salts, cellulose, etc.

[0093] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium germanium phosphorus sulfide, silver sulfide germanium ore), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0094] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0095] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0096] In some implementations, the electrode assembly is a stacked structure.

[0097] As an example, multiple positive and negative electrodes can be set, and multiple positive and multiple negative electrodes can be stacked alternately.

[0098] As an example, multiple positive electrode plates can be provided, and negative electrode plates can be folded to form multiple stacked folded segments, with a positive electrode plate sandwiched between adjacent folded segments.

[0099] As an example, both the positive and negative electrode plates are folded to form multiple stacked folded segments.

[0100] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0101] As an example, the separators can be continuously arranged, either by folding or rolling between any adjacent positive or negative electrode plates.

[0102] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0103] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0104] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as electrode assemblies and electrolytes. The housing may be made of steel, aluminum, plastic (such as polypropylene), composite metal (such as copper-aluminum composite), or aluminum-plastic film, etc.

[0105] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not have any particular limitations.

[0106] The battery mentioned in the embodiments of this application refers to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0107] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0108] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells, with the individual battery cells or battery modules housed within the housing.

[0109] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0110] In some embodiments, the battery can be an energy storage device. Energy storage devices include energy storage containers, energy storage cabinets, etc.

[0111] The development of battery technology must take into account multiple design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate and other performance parameters. In addition, battery reliability also needs to be considered.

[0112] The pressure relief mechanism on a battery cell has a significant impact on its reliability. For example, in the event of a short circuit or overcharging, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure. In such cases, the pressure relief mechanism can be activated to release the internal pressure, reducing the risk of battery cell explosion and fire.

[0113] A pressure relief mechanism is a component or part that is activated to release internal gases when the internal pressure or temperature of a battery cell reaches a predetermined threshold. This threshold design varies depending on design requirements. It may depend on the materials of one or more of the components in the battery cell: the positive electrode, negative electrode, electrolyte, and separator.

[0114] The pressure relief mechanism can take the form of an explosion-proof valve, a gas valve, a pressure relief valve, or a safety valve, and can specifically employ a pressure-sensitive element or structure. That is, when the internal pressure of a battery cell reaches a predetermined threshold, the pressure relief mechanism actuates or a weak point in the pressure relief mechanism ruptures, thereby creating an opening or channel for internal pressure release. Alternatively, the pressure relief mechanism can also employ a temperature-sensitive element or structure, that is, when the internal temperature of a battery cell reaches a predetermined threshold, the pressure relief mechanism actuates, thereby creating an opening or channel for internal pressure release.

[0115] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to, at least a portion of the mechanism rupturing, breaking, tearing, or opening. When the pressure relief mechanism is actuated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the actuated portion. This method allows for pressure relief of the battery cell under controlled pressure, thereby preventing potentially more serious accidents.

[0116] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0117] A battery typically contains multiple individual cells. When a cell experiences thermal runaway, the high-temperature substances inside that cell (such as high-temperature gases or particles) are released after the pressure relief mechanism is activated. As the released high-temperature gas flows through normal cells, it may heat the pressure relief mechanism of those cells, potentially causing it to crack and fail. This can lead to problems such as cell failure and thermal runaway, affecting the battery's reliability.

[0118] In view of this, the present application provides a technical solution that covers the outside of the pressure relief mechanism with a protective component with a high melting point to isolate 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.

[0119] The battery cells described in the embodiments of this application are applicable to batteries and electrical devices that use batteries.

[0120] The battery cell, battery, and electrical device disclosed in this application can be used in electrical devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., while spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0121] For ease of explanation, the following embodiments will use a vehicle as an example of an electrical device.

[0122] Figure 1 The diagram shows the structural features of a vehicle provided in some embodiments of this application.

[0123] like Figure 1 As shown, a battery 2 is installed inside the vehicle 1. The battery 2 can be located at the bottom, front, or rear of the vehicle 1. The battery 2 can be used to power the vehicle 1; for example, the battery 2 can serve as the operating power source for the vehicle 1.

[0124] Vehicle 1 may also include controller 3 and motor 4. Controller 3 is used to control battery 2 to supply power to motor 4, for example, for the power needs of vehicle 1 during start-up, navigation and driving.

[0125] In some embodiments of this application, the battery 2 can not only serve as the operating power source for the vehicle 1, but also as the driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0126] Figure 2 This is a schematic diagram of a battery explosion provided for some embodiments of this application. For example... Figure 2 As shown, battery 2 includes a housing 5 and a battery cell 6, with the battery cell 6 housed inside the housing 5.

[0127] The housing 5 is used to house the battery cell 6, and the housing 5 can have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, which overlap each other, and together define a housing space 5c for housing the battery cell 6. The second housing portion 5b may be a hollow structure with one end open, and the first housing portion 5a may be a plate-like structure, with the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c; alternatively, both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, with the open side of the first housing portion 5a covering the open side of the second housing portion 5b to form a housing 5 with the housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b can be various shapes, such as cylinders, cuboids, etc.

[0128] To improve the sealing performance after the first housing part 5a and the second housing part 5b are connected, a sealing element, such as sealant or sealing ring, can also be provided between the first housing part 5a and the second housing part 5b.

[0129] Assuming that the first box section 5a covers the top of the second box section 5b, the first box section 5a can also be called the upper box cover, and the second box section 5b can also be called the lower box.

[0130] In battery 2, there can be one or more battery cells 6. If there are multiple battery cells 6, they can be connected in series, in parallel, or in a mixed manner. A mixed connection means that multiple battery cells 6 are connected in both series and parallel. Multiple battery cells 6 can be directly connected in series, in parallel, or in a mixed manner, and then the whole assembly of multiple battery cells 6 is housed in the housing 5. Alternatively, multiple battery cells 6 can first be connected in series, in parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, in parallel, or in a mixed manner to form a whole assembly, which is then housed in the housing 5.

[0131] Figure 3 This is an exploded schematic diagram of a battery cell provided in some embodiments of this application; Figure 4 A cross-sectional schematic diagram of a battery cell provided in some embodiments of this application; Figure 5 for Figure 4 Enlarged view of the area within the circle; Figure 6 for Figure 5 Enlarged illustration within the box; Figure 7 for Figure 6 Enlarged view of the area within the circle.

[0132] Reference Figures 3 to 7This application provides a battery cell 6, which includes a housing 20, an electrode assembly 10, and other functional components (such as electrode terminals 30 disposed on the housing 20), with at least a portion of the electrode assembly 10 housed within the housing 20.

[0133] The outer shell 20 is a hollow structure, forming an internal space for accommodating the electrode assembly 10 and the electrolyte. The shape of the outer shell 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a cuboid structure, a cuboid outer shell can be used; if the electrode assembly 10 is a cylindrical structure, a cylindrical outer shell can be used.

[0134] As an example, the housing 20 includes a housing 21 and an end cap 22, the housing 21 having an opening and the end cap 22 for closing the opening.

[0135] The housing 21 is a component used to fit the end cap 22 to form the internal cavity of the battery cell 6. The formed internal cavity can be used to accommodate the electrode assembly 10, electrolyte, and other components.

[0136] The housing 21 and the end cap 22 can be separate components. For example, an opening can be provided on the housing 21, and the end cap 22 can be used to close the opening to form an internal cavity for the battery cell 6.

[0137] The housing 21 can have various shapes and sizes, such as cuboid, cylindrical, 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 material of the housing 21 can be various, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and this application embodiment does not impose any special limitations on this.

[0138] 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 (such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when subjected to compression and impact, so that the battery cell 6 can have higher structural strength and improve reliability.

[0139] The end cap 22 is connected to the housing 21 by welding, bonding, snap-fitting or other means.

[0140] The housing 21 may be open at one end or open at both ends. In some examples, the housing 21 may be a structure with an opening on one side, and one end cap 22 is provided to cover the housing 21. In other examples, the housing 21 may also be a structure with openings on both sides, and two end caps 22 are provided, with the two end caps 22 respectively covering the two openings of the housing 21.

[0141] Electrode terminal 30 can be used to electrically connect to electrode assembly 10 for outputting or inputting electrical energy of battery cell 6.

[0142] Electrode assembly 10 is a component in the battery cell 6 where electrochemical reactions occur. The housing 21 may contain one or more electrode assemblies 10.

[0143] As an example, the electrode assembly 10 includes a positive electrode and a negative electrode. The portions of the positive and negative electrode having active material constitute the main body of the electrode assembly 10, and the portions of the positive and negative electrode without active material each constitute a tab. The tab 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 at opposite ends of the main body.

[0144] During the charging and discharging process of 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.

[0145] In some embodiments, the battery cell 6 includes a housing 20 and a pressure relief mechanism 40. The housing 20 includes a wall 211, and the pressure relief mechanism 40 is disposed on the wall 211. The pressure relief mechanism 40 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold to release gas inside the housing 20.

[0146] As an example, wall 211 can be end cap 22 or a wall of housing 21.

[0147] As an example, the shape of the wall portion 211 can be circular, rectangular, elliptical, or other shapes.

[0148] In some examples, the pressure relief mechanism 40 and the wall portion 211 are independently formed components, which can be connected by welding, bonding, or other means. For example, the wall portion 211 has a pressure relief hole that extends through the wall portion 211, and the pressure relief mechanism 40 is mounted on the wall portion 211 and covers the pressure relief hole to separate the spaces on the inner and outer sides of the wall portion 211. In alternative embodiments, the pressure relief mechanism 40 and the wall portion 211 may also be an integrally formed structure.

[0149] The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 6.

[0150] 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 inside the casing 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 or fragments, can also be released.

[0151] The internal pressure of the battery cell 6 can be the same as the internal pressure of the casing 20, and the internal temperature of the battery cell 6 can be the same as the internal temperature of the casing 20.

[0152] The pressure relief mechanism 40 can be triggered by the internal pressure of the housing 20 alone, or by the internal temperature of the housing 20 alone, or by a combination of the internal pressure and internal temperature of the housing 20.

[0153] As an example, during thermal runaway of battery cell 6, as gas accumulates inside casing 20, the internal pressure of casing 20 may reach or even exceed a pressure threshold. When the internal pressure of casing 20 reaches the threshold, pressure relief mechanism 40 is activated and forms an exhaust channel to connect the internal space of casing 20 with the external space. Gas inside casing 20 can be discharged through the exhaust channel, thereby reducing the risk of battery cell 6 exploding.

[0154] As an example, when the electrolyte and active material react and rapidly release heat, the internal temperature of the casing 20 will rise, which will also cause the internal pressure of the casing 20 to rise. When the internal temperature of the casing 20 reaches a threshold, the pressure relief mechanism 40 can be actuated under the action of temperature and pressure to form an exhaust channel, so that the internal space of the casing 20 is connected to the external space. The gas inside the casing 20 can be discharged through the exhaust channel, thereby reducing the risk of battery cell 6 explosion.

[0155] In some embodiments, the battery cell 6 further includes a protective member 50, the protective member 50 having a melting point 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.

[0156] The melting point of the protective component 50 refers to the melting point of the protective component 50 under atmospheric pressure. Optionally, the melting point of the protective component 50 may be 300℃, 500℃, 700℃, 900℃, 1000℃, 1500℃, 2000℃ or 2500℃.

[0157] In the thickness direction Z of the wall portion 211, at least a portion of the protective member 50 is located on the side of the pressure relief mechanism 40 opposite to the electrode assembly 10. In the thickness direction Z of the wall portion 211, the projection of the protective member 50 at least partially overlaps with the projection of the pressure relief mechanism 40.

[0158] In the thickness direction Z, the protective component 50 may completely cover the pressure relief mechanism 40, or it may only cover a part of the pressure relief mechanism 40.

[0159] In the thickness direction Z, the protective component 50 can be spaced apart from the pressure relief mechanism 40, or they can be in contact with each other.

[0160] The protective component 50 can be connected to the wall 211 or to the pressure relief mechanism 40.

[0161] As an example, when the pressure relief mechanism 40 is actuated, the protective member 50 may rupture, break, open, fly out, or perform other actions under the internal pressure of the battery cell 6, so as to reduce the obstruction of the protective member 50 to the gas.

[0162] When thermal runaway occurs in battery cell 6, the pressure relief mechanism 40 is activated and releases the gas inside the casing 20 to the outside, reducing the risk of battery cell 6 explosion and fire, and improving the reliability of battery cell 6. The protective component 50 can isolate external impurities (such as dust, particles, etc.), reducing the corrosion or damage of impurities to the pressure relief mechanism 40, and improving the reliability of the pressure relief mechanism 40. The protective component 50 has a melting point greater than or equal to 300℃ and can withstand high thermal shock. When high-temperature substances (such as high-temperature gases released from other battery cells 6) flow through battery cell 6, the protective component 50 can withstand the thermal shock of the high-temperature substances and is not prone to deformation or melting under high temperatures, thereby isolating at least part of the high-temperature substances 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 battery cell 6.

[0163] In some embodiments, the pressure relief mechanism 40 is provided with a weak portion 41. The weak portion 41 is a relatively weak part of the pressure relief mechanism 40, which is a part of the pressure relief mechanism 40 that is prone to breakage, fracture, tearing, or opening. Exemplarily, the strength of the pressure relief mechanism 40 is less than the strength of the portion of the pressure relief mechanism 40 near the weak portion 41.

[0164] In some examples, this application may create grooves, notches, through holes, or other structures 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 may be 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 treatment may be performed on a predetermined area of ​​the pressure relief mechanism 40 so that the strength of this area is weaker than the strength of other areas; in other words, this area is the weak portion 41.

[0165] The weak point 41 can rupture when the internal pressure or temperature of the battery cell 6 reaches a threshold, so as to release the gas inside the casing 20.

[0166] In some embodiments, the pressure relief mechanism 40 and the wall portion 211 are separately formed components that 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 a region surrounded by the weak portion 41.

[0167] In some embodiments, the protective member 50 covers the weak portion 41 in the thickness direction Z. The protective member 50 may cover a portion of the weak portion 41 or completely cover the weak portion 41 in the thickness direction Z.

[0168] The protective component 50 can reduce the risk of high-temperature materials directly impacting the weak part 41, reduce the thermal shock to the weak part 41, reduce the risk of cracking and failure of the weak part 41, and improve the reliability of the battery cell 6.

[0169] Optionally, in the thickness direction Z, the protective component 50 completely covers the weak part 41.

[0170] 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, so that the protective member 50 completely covers the pressure relief mechanism 40.

[0171] In some embodiments, the wall portion 211 has an outer surface 212, and the wall portion 211 is provided with a receiving recess 213 that is recessed relative to the outer surface 212.

[0172] The outer surface 212 may be the surface of the wall portion 211 that faces away from the electrode assembly 10. Optionally, the outer surface 212 may be a plane.

[0173] As an example, the shape of the recess 213 can be columnar, conical, stepped, or other shapes.

[0174] 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.

[0175] By opening the receiving recess 213 and placing at least a portion of the protective member 50 in the receiving 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.

[0176] In some embodiments, the protective member 50 is fully accommodated in the receiving recess 213. In the thickness direction Z, the protective member 50 does not extend beyond the outer surface 212 from the surface of the pressure relief mechanism 40.

[0177] The embodiments of this application can further improve the space utilization and energy density of the battery cell 6. In addition, by completely accommodating the protective member 50 within the receiving recess 213, the risk of friction between the protective member 50 and the external structure can be reduced during the production, transportation, and use of the battery cell 6, thereby improving the reliability of the protective member 50.

[0178] In some embodiments, the bottom wall 214 of the receiving recess 213 is provided with a through hole 215, and the pressure relief mechanism 40 is received in the receiving recess 213, connected to the bottom wall 214 and covering the through hole 215.

[0179] When the pressure relief mechanism 40 is activated, an exhaust channel is formed, and the gas inside the housing 20 can be released to the outside of the battery cell 6 through the through hole 215 and the exhaust channel.

[0180] In some embodiments, the protective member 50 and the pressure relief mechanism 40 are spaced apart in the thickness direction Z.

[0181] The embodiments of this 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 substances, thereby reducing the temperature rise of the pressure relief mechanism 40 and reducing the risk of cracking and failure of the pressure relief mechanism 40.

[0182] In some embodiments, the receiving recess 213 is stepped, and a stepped surface 213a is provided on the side wall of the receiving recess 213. The protective member 50 is connected to the stepped surface 213a, thereby being spaced apart from the pressure relief mechanism 40.

[0183] In some embodiments, there are no other components between the protective member 50 and the pressure relief mechanism 40 in the thickness direction Z.

[0184] In this embodiment, a heat-insulating cavity is formed between the protective member 50 and the pressure relief mechanism 40 to reduce the heat transfer rate between them. By not providing other solid components between the protective member 50 and the pressure relief mechanism 40, obstruction of gas when the pressure relief mechanism 40 is actuated is reduced, and heat conduction between the solid structure and the protective member 50 and the pressure relief mechanism 40 is also avoided to some extent, thus reducing the heat transfer rate between them.

[0185] In some embodiments, the minimum distance between the protective member 50 and the pressure relief mechanism 40 in the thickness direction Z is D, and the minimum thickness of the protective member 50 is t. D and t satisfy: t × D ≥ 0.01 mm 2 .

[0186] The larger the value of t, the lower the temperature of the surface of the protective component 50 facing the pressure relief mechanism 40 when a high-temperature substance impacts the protective component 50, and the less heat the protective component 50 radiates towards the pressure relief mechanism 40. The smaller the value of t, the higher the temperature of the surface of the protective component 50 facing the pressure relief mechanism 40 when a high-temperature substance impacts the protective component 50, and the more heat the protective component 50 radiates towards the pressure relief mechanism 40.

[0187] The larger the value of D, the longer the heat transfer path between the protective component 50 and the pressure relief mechanism 40 when a high-temperature substance impacts the protective component 50; the smaller the value of D, the shorter the heat transfer path between the protective component 50 and the pressure relief mechanism 40.

[0188] In this embodiment, t×D is defined as greater than or equal to 0.01 mm. 2 This can reduce the temperature rise of the pressure relief mechanism 40 when the protective component 50 is impacted by high-temperature materials, thereby reducing the risk of cracking and failure of the pressure relief mechanism 40.

[0189] As an example, t×D is 0.01mm. 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 .

[0190] Optionally, t×D≥0.05mm 2 Alternatively, t×D≥0.1mm 2 .

[0191] In some embodiments, t is 0.05mm-0.4mm.

[0192] In this embodiment, t is limited to greater than or equal to 0.05 mm. This reduces the heat radiated from the protective component 50 to the pressure relief mechanism 40 when subjected to impact from high-temperature substances, thus lowering the temperature rise of the pressure relief mechanism 40. A larger t results in greater space and weight occupied by the protective component 50. Limiting t to less than or equal to 0.4 mm allows for a reduction in the space and weight occupied by the protective component 50 while still meeting its protective requirements, thereby increasing the energy density of the battery cell 6.

[0193] Optionally, t is 0.05mm, 0.06mm, 0.08mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.22mm, 0.25mm, 0.3mm, 0.32mm, 0.35mm or 0.4mm.

[0194] In some embodiments, t is 0.08mm-0.2mm, so as to reduce the space and weight occupied by the protective component 50 and increase the energy density of the battery cell 6 while meeting the protection requirements of the protective component 50.

[0195] 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, making it less prone to melting under thermal shock, thus providing better thermal shock resistance and reducing the risk of the protective member 50 being melted through.

[0196] In some embodiments, the melting point of the protective member 50 is greater than or equal to 1000°C.

[0197] In some embodiments, the material of the protective member 50 includes mica, rubber, ceramic or polyimide.

[0198] Mica, rubber, ceramics and polyimide have good thermal shock resistance, thus providing protection for the pressure relief mechanism 40 and reducing the risk of failure and cracking of the pressure relief mechanism 40.

[0199] 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 100MPa-350MPa.

[0200] For example, using a thin film tensile strength tester, a gradually increasing tensile load is applied along the length of a standard specimen at an ambient temperature of 150°C, causing it to deform until it fails. The maximum tensile stress required for the specimen to fail is the tensile strength. Tensile strength can also be called tensile resistance.

[0201] The greater the tensile strength of the protective component 50, the more difficult it is for it to break when the pressure relief mechanism 40 is actuated. In this embodiment, the tensile strength of the protective component 50 at 150°C is set to be less than or equal to 350 MPa, which can make the protective component 50 break in time when the pressure relief mechanism 40 is actuated, thereby improving the exhaust efficiency.

[0202] The lower the tensile strength of the protective component 50, the greater its deformation under external air pressure fluctuations; and the more time it is used, the more prone the protective component 50 is to fatigue deformation. In this embodiment, the tensile strength of the protective component 50 at 150°C is set to be greater than or equal to 100 MPa, which can slow down the aging of the protective component and extend the service life of the battery cell 6.

[0203] Optionally, the tensile strength of the protective component 50 at 150°C is 100MPa, 120MPa, 150MPa, 170MPa, 200MPa, 220MPa, 250MPa, 270MPa, 300MPa, 320MPa or 350MPa.

[0204] In some embodiments, the tensile strength of the protective member 50 at 150°C is 170MPa-250MPa.

[0205] In some embodiments, the housing 20 includes a housing 21 and an end cap 22, one end of the housing 21 having an opening, and the end cap 22 being connected to the housing 21 and covering the opening.

[0206] For example, when the battery cell 6 is used upright, the end cap 22 is located above the electrode assembly 10 in the direction of gravity. When the battery cell 6 is used upside down, the end cap 22 is located below the electrode assembly 10 in the direction of gravity.

[0207] In some embodiments, the housing 21 includes a wall portion 211 opposite to the end cap 22. By providing the pressure relief mechanism 40 on the housing 21, more installation space can be reserved for components on the end cap 22, for example, more installation space can be reserved for the electrode terminal 30.

[0208] In some embodiments, the thickness direction Z of the wall portion 211 is parallel to the gravity direction, and the wall portion 211 is located below the electrode assembly 10 in the gravity direction.

[0209] The wall portion 211 can provide support for the electrode assembly 10, improving its stability. In the event of thermal runaway of the battery cell 6, gas can be ejected downwards, thereby reducing exhaust resistance and improving exhaust efficiency.

[0210] 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.

[0211] Figure 8 for Figure 5 Enlarged view of the area within the circle; Figure 9 This is a top view of the protective components and connecting layers of a battery cell provided in some embodiments of this application.

[0212] Please refer to the above as well. Figures 6 to 9 In some embodiments, the battery cell 6 further includes a connecting layer 60, through which the protective member 50 is connected to the wall portion 211.

[0213] The connecting layer 60 can be connected to the wall portion 211 and the protective member 50 in various ways. In some examples, the connecting layer 60 can bond the protective member 50 to the wall portion 211. In other examples, the connecting layer 60 is fused to the protective member 50 and the wall portion 211.

[0214] In some embodiments, the connecting layer 60 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold, so that at least a portion of the protective member 50 is disengaged from the wall portion 211.

[0215] When the internal pressure or temperature of the battery cell 6 reaches a threshold, the protective component 50 may detach entirely from the wall 211, or only partially from the wall 211.

[0216] "At least a portion of the protective member 50 is detached from the wall portion 211" can mean that at least a portion of the protective member 50 is no longer bound by the wall portion 211 and can deviate from its initial set position.

[0217] "Actuation of the connecting layer 60" refers to the connecting layer 60 being activated or moving to a certain state, thereby causing at least a portion of the protective member 50 to detach from the wall portion 211. The actions of the connecting layer 60 may include, but are not limited to: at least a portion of the connecting layer 60 being disconnected from the wall portion 211, at least a portion of the connecting layer 60 being disconnected from the protective member 50, the connecting layer 60 being torn, etc.

[0218] When the internal pressure or temperature of the battery cell 6 reaches a threshold, the pressure relief mechanism 40 is activated and releases the gas inside the casing 20. Under the action of other internal forces, at least a portion of the protective member 50 disengages 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.

[0219] In some embodiments, the connecting layer 60 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold, so that the entire protective member 50 is detached from the wall portion 211. When a short circuit, overcharge, or other phenomenon occurs, the pressure relief mechanism 40 is actuated, and the protective member 50 can detach 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 the battery cell 6 exploding.

[0220] In other embodiments, the protective member 50 may also rupture when actuated by the internal pressure or temperature of the battery cell 6 reaching a threshold, thereby releasing gas from the casing 20.

[0221] In some embodiments, the bonding layer 60 includes an adhesive layer.

[0222] 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.

[0223] When the battery cell 6 experiences thermal runaway, the heat can be conducted to the connecting layer 60, which softens, allowing the protective component 50 to detach from the wall 211 in time when the pressure relief mechanism 40 is activated.

[0224] In some embodiments, the connecting layer 60 is disposed on the outer peripheral region of the surface of the protective member 50 facing the pressure relief mechanism 40.

[0225] By placing the connecting layer 60 in the outer peripheral area of ​​the protective member 50, the amount of connecting layer 60 used can be reduced, and the risk of the connecting layer 60 being connected to the pressure relief mechanism 40 can be reduced.

[0226] In some embodiments, the connecting layer 60 is located entirely between the wall portion 211 and the protective member 50 in the thickness direction Z.

[0227] In some embodiments, a clearance space 70 is formed between the protective member 50 and the pressure relief mechanism 40, and a connecting channel 80 is provided between the protective member 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 clearance space 70.

[0228] During the charging and discharging process of battery cell 6, the internal air pressure of battery cell 6 will fluctuate slightly. When the internal air pressure of battery cell 6 fluctuates, the pressure relief mechanism 40 may bulge outward. In this embodiment of the application, by providing a connecting flow channel 80 to connect the clearance space 70 with the external environment, the air pressure change in the clearance space 70 when the pressure relief mechanism 40 bulges is reduced, thereby reducing the deformation of the protective component 50.

[0229] In addition, during the production process of battery cell 6, the airtightness of the pressure relief mechanism 40 can be detected by connecting the flow channel 80 and the clearance space 70.

[0230] In some embodiments, when the connecting layer 60 is provided, the connecting layer 60 may be left open, thereby forming a connecting channel 80 with the connecting layer 60, the wall portion 211 and the protective member 50.

[0231] Figure 10 Top view of the protective member and connecting layer of the battery cell provided in other embodiments of this application; Figure 11 for Figure 10 The diagram shows a cross-sectional view of the protective components and connecting layers.

[0232] like Figure 10 and Figure 11 As shown, in some embodiments, the connecting channel 80 includes a groove 51 provided on the surface of the protective member 50 facing the pressure relief mechanism 40.

[0233] A groove 51 is provided on the surface of the pressure relief mechanism 40 to connect the clearance space 70 with the external environment of the battery cell 6.

[0234] In some embodiments, the connecting layer 60 and the groove 51 do not overlap in the thickness direction Z to reduce the risk of the connecting layer 60 filling into the groove 51.

[0235] Figure 12 A schematic diagram of a battery provided for some embodiments of this application; Figure 13 A cross-sectional schematic diagram of a battery provided in some embodiments of this application; Figure 14 for Figure 13 Enlarged illustration within the box; Figure 15 for Figure 14 Enlarged view of the area within the circle.

[0236] Reference Figures 12 to 15 This application also provides a battery 2, which includes a plurality of battery cells 6 provided in any of the foregoing embodiments.

[0237] In some embodiments, the battery 2 further includes a housing 5, within which a plurality of battery cells 6 are housed. The housing 5 includes a first housing wall 5d, with a wall portion 211 disposed at one end of the housing 20 facing the first housing wall 5d. A channel 5e is provided on the inner side of the first housing wall 5d. In the thickness direction Z, the projection of the pressure relief mechanism 40 of the plurality of battery cells 6 lies within the projection of the channel 5e. In the thickness direction Z, a protective member 50 is located between the channel 5e and the pressure relief mechanism 40.

[0238] When thermal runaway occurs in battery cell 6, the pressure relief mechanism 40 is activated, releasing the gas inside the casing 20 into the channel 5e. The channel 5e guides the flow of high-temperature gas to exhaust it to the outside of the housing 5, reducing the risk of battery 2 explosion. As the high-temperature gas flows along the channel 5e, the protective component 50 can isolate the high-temperature gas from the pressure relief mechanism 40, reducing the heat conducted to the pressure relief mechanism 40, lowering the risk of cracking and failure of the pressure relief mechanism 40, simplifying the continued deterioration of thermal runaway, and improving the reliability of battery 2.

[0239] In some embodiments, the projection of the protective member 50 lies 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 inside the housing 20; the embodiments of this application can reduce the risk of the first housing wall 5d interfering with the protective member 50, allowing the protective member 50 to smoothly enter the channel 5e.

[0240] In some embodiments, the dimension of channel 5e is larger than the dimension of protective member 50 in any direction perpendicular to the thickness direction Z.

[0241] For example, in the length direction X of the wall portion 211, the size of the channel 5e 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 5e is larger than the size of the protective member 50.

[0242] The embodiments of this application can reduce the problem of interference between the first box wall 5d and the protective component 50 due to assembly errors, so that the protective component 50 can smoothly enter the channel 5e when the battery cell 6 thermally runs away.

[0243] According to some embodiments of this application, this application also provides an electrical device, including a battery 2 from any of the above embodiments, wherein the battery 2 is used to provide electrical energy to the electrical device. The electrical device can be any of the aforementioned devices or systems that utilize the battery 2.

[0244] Reference Figures 3 to 8This application provides a battery cell 6, which includes a housing 20, an electrode assembly 10, a pressure relief mechanism 40, a protective component 50, and a connecting layer 60.

[0245] The electrode assembly 10 is housed within the housing 20.

[0246] The housing 20 includes a housing 21 and an end cap 22. One end of the housing 21 has an opening, and the end cap 22 is connected to the housing 21 and closes the opening. The housing 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 below the electrode assembly 10 in the direction of gravity.

[0247] The wall portion 211 has an outer surface 212 on the side opposite to the electrode assembly 10, and the wall portion 211 is provided with a receiving recess 213 that is recessed relative to the outer surface 212. The bottom wall 214 of the receiving recess 213 is provided with a through hole 215, and the pressure relief mechanism 40 is accommodated in the receiving recess 213, connected to the bottom wall 214, and covers the through hole 215.

[0248] The protective member 50 is entirely housed in the receiving recess 213 and is located on the side of the pressure relief mechanism 40 opposite to the electrode assembly 10. In the thickness direction Z, the protective member 50 is spaced apart from the pressure relief mechanism 40, and the protective member 50 completely covers the pressure relief mechanism 40.

[0249] The side wall of the recess 213 is provided with a stepped surface 213a, and the connecting layer 60 is located between the stepped surface 213a and the protective member 50 to connect the protective member 50 to the wall 211.

[0250] The pressure relief mechanism 40 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold to release gas inside the casing 20. The connecting layer 60 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold to disengage the protective member 50 from the wall portion 211.

[0251] The protective component 50 has a melting point greater than 500°C. Optionally, the protective component 50 is a mica plate.

[0252] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This 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 by, include: The outer casing, including the walls; A pressure relief mechanism is provided on the wall portion, which can be actuated when the internal pressure or temperature of the battery cell reaches a threshold to release gas inside the casing; as well as A protective member having a melting point greater than or equal to 300°C, covering at least a portion of the pressure relief mechanism in the thickness direction of the wall portion, and the protective member being spaced apart from the pressure relief mechanism.

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

3. The battery cell of claim 2, wherein, The protective component is completely accommodated in the accommodating recess.

4. The battery cell according to claim 2, characterized in that, The bottom wall of the receiving recess is provided with a through hole, and the pressure relief mechanism is accommodated in the receiving recess, connected to the bottom wall, and covers the through hole.

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

6. The battery cell according to claim 4, characterized in that, 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 x D > 0.01 mm 2 .

7. The battery cell of claim 6, wherein, t is 0.05mm-0.4mm.

8. The battery cell according to claim 7, characterized in that, t is 0.08mm-0.2mm.

9. The battery cell of any one of claims 1-8, wherein, The battery cell further includes a connecting layer, and the protective component is connected to the wall portion through the connecting layer; The connecting layer can be actuated when the internal pressure or temperature of the battery cell reaches a threshold, so that at least a portion of the protective member detaches from the wall.

10. The battery cell of claim 9, wherein, The bonding layer includes an adhesive layer.

11. The battery cell of claim 9, wherein, The connecting layer is disposed on the outer peripheral region of the surface of the protective member facing the pressure relief mechanism.

12. The battery cell of claim 9, wherein, A clearance space is formed between the protective component and the pressure relief mechanism. A connecting channel is provided between the protective component and the wall. One end of the connecting channel is connected to the outside, and the other end is connected to the clearance space.

13. The battery cell of claim 12, wherein, The connecting channel includes a groove disposed on the surface of the protective member facing the pressure relief mechanism.

14. The battery cell of claim 1, wherein, The melting point of the protective component is greater than or equal to 500°C.

15. The battery cell of claim 1, wherein, The protective components are made of mica, rubber, ceramic or polyimide.

16. The battery cell of claim 1, wherein, The protective component is made of polyimide, and its tensile strength at 150°C is 100MPa-350MPa.

17. The battery cell of claim 1, wherein, The battery cell also includes an electrode assembly housed within the casing; The thickness direction of the wall is parallel to the direction of gravity, and the wall is located on the lower side of the electrode assembly in the direction of gravity.

18. The battery cell according to claim 1, characterized in that, The housing includes a shell and an end cap, one end of the shell having an opening, and the end cap being connected to the shell and covering the opening; the shell includes a wall portion opposite to the end cap.

19. A battery, characterized by It includes the battery cells according to any one of claims 1-18.

20. The battery of claim 19, wherein, The battery also includes a housing, in which multiple battery cells are housed; The enclosure includes a first enclosure wall, and the wall portion is located at the end of the outer shell facing the first enclosure wall; The inner side of the first box wall is provided with a channel; in the thickness direction, the projection of the pressure relief mechanism of the plurality of battery cells is located within the projection of the channel; In the thickness direction, the protective member is located between the channel and the pressure relief mechanism.

21. The battery of claim 20, wherein, In the thickness direction, the projection of the protective member lies within the projection of the channel.

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

23. An electrical device, comprising: Includes a battery according to any one of claims 19-22, the battery being used to provide electrical energy.

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