Battery cell, battery and electric device

Abstract

The invention discloses a battery monomer, a battery and a power utilization device. The battery cell includes a housing, a pressure relief mechanism, and a protective member. The housing includes a wall portion. The pressure relief mechanism is arranged on the wall part, and the pressure relief mechanism can be actuated under the condition that the internal pressure or temperature of the battery cells reaches a threshold value so as to release gas in the shell. The protective member has a melting point of 300 DEG C or more, and covers at least a portion of the pressure relief mechanism in the thickness direction of the wall portion.

Description

Technical Field

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

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

[0003] How to improve the reliability of battery cells is an important research direction in the industry. Summary of the invention

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

[0005] In a first aspect, the present application provides a battery cell, which includes a housing, a pressure relief mechanism and a protective member. The housing includes a wall portion. The pressure relief mechanism is disposed on the wall portion, and the pressure relief mechanism can be actuated to release the gas in the housing when the internal pressure or temperature of the battery cell reaches a threshold value. The melting point of the protective member is greater than or equal to 300°C, and in the thickness direction of the wall portion, the protective member covers at least part of the pressure relief mechanism.

[0006] When thermal runaway occurs in the battery cell, the pressure relief mechanism is activated and releases the gas in the shell to the outside to reduce the risk of explosion and fire of the battery cell and improve 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 substances flow through the battery cell, the protective component can withstand the thermal shock of high-temperature substances and is not prone to deformation, melting through, and other problems under high temperature, thereby isolating at least part of the high-temperature substances from the pressure relief mechanism, reducing the heat conducted to the pressure relief mechanism, reducing the risk of cracking and failure of the pressure relief mechanism, and improving the reliability of the battery cell.

[0007] 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. At least a portion of the protective member is accommodated in the accommodating recess.

[0008] By providing a receiving recess and disposing at least a portion of the protection member in the receiving 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.

[0009] In some embodiments, the guard member is completely received in the receiving recess.

[0010] The embodiment of the present application can further improve the space utilization and energy density of the battery cell. In addition, the protective member is completely contained in the containing recess, which can reduce the risk of friction between the protective member and the external structure during the production, transportation and use of the battery cell, and improve the reliability of the protective member.

[0011] In some embodiments, 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 protective member and the pressure relief mechanism are spaced apart. In the embodiment of the present application, when the protective member is subjected to thermal shock of a high-temperature substance, the heat transfer rate between the protective member and the pressure relief mechanism can be reduced, the temperature rise of the pressure relief mechanism can be reduced, and the risk of cracking and failure of the pressure relief mechanism can be reduced.

[0012] In some embodiments, in the thickness direction, there are no other components between the protective member and the pressure relief mechanism.

[0013] An insulating cavity is formed between the protective component and the pressure relief mechanism to reduce the heat transfer rate between the protective component and the pressure relief mechanism. No other solid components are arranged between the protective component and the pressure relief mechanism, which can reduce the obstruction to the gas when the pressure relief mechanism is actuated, and can also avoid heat conduction of the solid structure between the protective component and the pressure relief mechanism to a certain extent, thereby reducing the heat transfer rate between the protective component and the pressure relief mechanism.

[0014] 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 .

[0015] The larger t is, the lower the temperature of the surface of the protective component facing the pressure relief mechanism when the high-temperature material 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 surface of the protective component facing the pressure relief mechanism when the high-temperature material 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 the high-temperature material impacts the protective component, and the smaller D is, the shorter the heat transfer path between the protective component and the pressure relief mechanism.

[0016] 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 protective components, the temperature rise of the pressure relief mechanism can be reduced, thereby reducing the risk of cracking and failure of the pressure relief mechanism.

[0017] In some embodiments, t is 0.05mm-0.4mm. By limiting t to be greater than or equal to 0.05mm, when a high-temperature substance impacts the protective component, the heat radiated from the protective component to the pressure relief mechanism can be reduced, 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; by limiting t to be less than or equal to 0.4mm, the space and weight occupied by the protective component can be reduced, thereby increasing the energy density of the battery cell, provided that the protective requirements of the protective component meet the requirements.

[0018] In some embodiments, t is 0.08 mm-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 under the premise that the protection requirements of the protective component meet the needs.

[0019] In some embodiments, the battery cell further comprises a connection layer, and the protective member is connected to the wall portion through the connection layer. The connection layer can be actuated when the internal pressure or temperature of the battery cell reaches a threshold value to separate at least part of the protective member from the wall portion.

[0020] When the internal pressure or temperature of the battery cell reaches a threshold, the pressure relief mechanism is activated to release the gas in the outer shell. Under the action of other internal factors, at least part of the protective component 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.

[0021] In some embodiments, the connecting layer includes a glue layer.

[0022] When the battery cell is in thermal runaway, the heat can be transferred to the connection layer, causing the connection layer to soften, thereby enabling the protective component to be separated from the wall portion in time when the pressure relief mechanism is actuated.

[0023] In some embodiments, the connection layer is disposed in the peripheral area of ​​the surface of the protective member facing the pressure relief mechanism. Disposing the connection layer in the peripheral area of ​​the protective member can save the amount of the connection layer and reduce the risk of the connection layer connecting with the pressure relief mechanism.

[0024] In some embodiments, an escape space is formed between the protective component and the pressure relief mechanism, and a connecting flow channel is provided between the protective component and the wall portion, one end of the connecting flow channel is connected to the outside, and the other end is connected to the escape space.

[0025] During the charge and discharge process of the battery cell, the internal air pressure of the battery cell will fluctuate slightly. When the internal air pressure of the battery cell fluctuates, the pressure relief mechanism may bulge outward. The embodiment of the present application provides a connecting flow channel to connect the escape space with the external environment, thereby reducing the pressure change in the escape space when the pressure relief mechanism bulges and reducing the deformation of the protective component. In addition, during the production process of the battery cell, the air tightness of the pressure relief mechanism can also be detected through the connecting flow channel and the escape space.

[0026] In some embodiments, the communication channel includes a groove disposed 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.

[0027] In some embodiments, the melting point of the protective member is greater than or equal to 500° C. The protective member has a higher melting point and is not easily melted when subjected to thermal shock, so that the protective member has better thermal shock resistance and reduces the risk of the protective member being melted through.

[0028] In some embodiments, the material of the protective member includes 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 and cracking of the pressure relief mechanism.

[0029] 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.

[0030] The greater the tensile strength of the protective member, the more difficult it is to rupture when the pressure relief mechanism is actuated. In the embodiment of the present application, the tensile strength of the protective member at 150°C is set to be less than or equal to 350 MPa, so that the protective member can be ruptured in time when the pressure relief mechanism is actuated, thereby improving the exhaust efficiency.

[0031] The smaller the tensile strength of the protective component, the greater the deformation of the protective component when the external air pressure fluctuates; as the use time increases, the protective component is more likely to be fatigued and deformed. In the embodiment of the present application, the tensile strength of the protective component at 150°C is set to be greater than or equal to 100MPa, which can slow down the aging of the protective component and extend the service life of the battery cell.

[0032] In some embodiments, the battery cell further includes an electrode assembly housed in the housing. The thickness direction of the wall portion is parallel to the direction of gravity, and the wall portion is located at the lower side of the electrode assembly in the direction of gravity. The wall portion can provide support for the electrode assembly and improve the stability of the electrode assembly. When the battery cell is in thermal runaway, the gas can be ejected downward, thereby reducing the exhaust resistance and improving the exhaust efficiency.

[0033] In some embodiments, the housing includes 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 includes a wall portion, the wall portion is opposite to the end cover. The pressure relief mechanism is arranged on the shell, and more installation space can be reserved for the components on the end cover.

[0034] 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.

[0035] In some embodiments, the battery further comprises a box body, wherein the plurality of battery cells are contained in the box body. The box body comprises a first box wall, wherein the wall portion is disposed at one end of the housing facing the first box wall. A channel is disposed on the inner side of the first box wall; in the thickness direction, the projection of the pressure relief mechanisms 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.

[0036] When thermal runaway occurs in a battery cell, the pressure relief mechanism is activated and releases the gas in the housing to the outside of the channel; the channel guides the high-temperature gas flow to discharge the high-temperature gas to the outside of the box, reducing the risk of battery explosion. During the flow of the high-temperature gas along the channel, the protective component can separate the high-temperature gas 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, simplify the continuous deterioration of thermal runaway, and improve the reliability of the battery.

[0037] In some embodiments, in the thickness direction, the projection of the guard member is located within the projection of the channel.

[0038] 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, so that the protective component can smoothly enter the channel.

[0039] In some embodiments, in any direction perpendicular to the thickness direction, the dimension of the channel is greater than the dimension of the guard member.

[0040] 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 thermally runs away.

[0041] In a third aspect, the present application provides an electrical device, comprising a battery according to any embodiment of the second aspect, and the battery is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The features, advantages and technical effects of exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0043] Figure 1 A schematic diagram of the structure of a vehicle provided in some embodiments of the present application;

[0044] Figure 2 An exploded schematic diagram of a battery provided in some embodiments of the present application;

[0045] Figure 3 An exploded schematic diagram of a battery cell provided in some embodiments of the present application;

[0046] Figure 4 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application;

[0047] Figure 5 for Figure 4 An enlarged schematic diagram at the circle frame;

[0048] Figure 6 for Figure 5 Enlarged schematic diagram at the box;

[0049] Figure 7 for Figure 6 An enlarged schematic diagram at the circle frame;

[0050] Figure 8 for Figure 5 An enlarged schematic diagram at the circle frame;

[0051] Fig. 9 A top view of a protective member and a connecting layer of a battery cell provided in some embodiments of the present application;

[0052] Fig.10 A top view of a protective member and a connecting layer of a battery cell provided in some other embodiments of the present application;

[0053] Fig.11 for Fig.10 A schematic cross-sectional view of the protective member and the connecting layer shown;

[0054] Fig.12 A schematic diagram of a battery provided for some embodiments of the present application;

[0055] Fig.13 A schematic cross-sectional view of a battery provided in some embodiments of the present application;

[0056] Fig.14 for Fig.13 Enlarged schematic diagram at the box;

[0057] Fig.15 for Fig.14 Enlarged diagram of the circle.

[0058] In the drawings, the drawings are not necessarily drawn to scale.

[0059] The reference numerals are as follows:

[0060] 1. Vehicle; 2. Battery; 3. Controller; 4. Motor; 5. Box; 5a. First box part; 5b. Second box part; 5c. Accommodation space; 5d. First box wall; 5e. Passage; 6. Battery cell;

[0061] 10. Electrode assembly;

[0062] 20, housing; 21, shell; 211, wall; 212, outer surface; 213, receiving recess; 213a, step surface; 214, bottom wall; 215, through hole; 22, end cover;

[0063] 30. Electrode terminal;

[0064] 40. Pressure relief mechanism; 41. Weak part;

[0065] 50. Protective member; 51. Groove;

[0066] 60. Connection layer;

[0067] 70. Avoidance space;

[0068] 80. Connecting flow channel;

[0069] X, length direction; Y, width direction; Z, thickness direction. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0071] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field of this application; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned drawings and any variations thereof are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship.

[0072] Reference to "embodiment" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0073] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0074] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the associated objects before and after are in an "or" relationship.

[0075] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0076] The term "plurality" used in the present application refers to two or more (including two).

[0077] 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.

[0078] The battery cell can be a lithium ion battery, a sodium ion battery, a sodium lithium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, a magnesium ion battery, a nickel hydrogen battery, a nickel cadmium battery, a lead storage battery, etc., which is not limited in the embodiments of the present application.

[0079] A battery cell generally includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator. During the charge and discharge process of the battery cell, active ions (such as lithium ions) are embedded and removed between the positive electrode and the negative electrode. The separator is set between the positive electrode and the negative electrode to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through.

[0080] In some embodiments, the positive electrode may be a positive electrode sheet, and the positive electrode sheet may include a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector.

[0081] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two facing surfaces of the positive electrode current collector.

[0082] As an example, the positive electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc., treated with silver surface, may be used. The composite current collector may include a polymer material base and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0083] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone or in combination of two or more. Among them, examples of lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 )), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds, etc.

[0084] In some embodiments, the positive electrode may be a foamed metal. The foamed metal may be a nickel foam, a copper foam, an aluminum foam, an alloy foam, or a carbon foam. When the foamed metal is used as the positive electrode, the positive electrode active material may not be provided on the surface of the foamed metal, but of course, the positive electrode active material may also be provided. As an example, a lithium source material, potassium metal or sodium metal may also be filled or / and deposited in the foamed metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0085] In some embodiments, the negative electrode may be a negative electrode sheet, and the negative electrode sheet may include a negative electrode current collector.

[0086] As an example, the negative electrode current collector can be a metal foil, a foamed metal or a composite current collector. For example, as a metal foil, aluminum or stainless steel treated with silver, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel or titanium, etc. can be used. The foamed metal can be a foamed nickel, a foamed copper, a foamed aluminum, a foamed alloy, or a foamed carbon, etc. The composite current collector can include a polymer material base and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0087] 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.

[0088] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0089] As an example, the negative electrode active material may adopt the negative electrode active material for battery cells known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0090] 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.

[0091] In some embodiments, the electrode assembly further includes a separator disposed between the positive electrode and the negative electrode.

[0092] 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 stability and mechanical stability can be selected.

[0093] 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 special restrictions. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without special restrictions. The separator can be a separate component located between the positive and negative electrodes, or it can be attached to the surface of the positive and negative electrodes.

[0094] In some embodiments, the separator is a solid electrolyte, which is disposed between the positive electrode and the negative electrode and serves to transmit ions and isolate the positive and negative electrodes.

[0095] In some embodiments, the battery cell further includes an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. The electrolyte can be liquid, gel or solid.

[0096] The liquid electrolyte includes an electrolyte salt and a solvent.

[0097] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0098] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone. The solvent can also be selected from ether solvents. Ether solvents can include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, diphenyl ether and crown ether.

[0099] Among them, the gel electrolyte includes a skeleton network with a polymer as the electrolyte, combined with an ionic liquid-lithium salt.

[0100] Among them, solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0101] As an example, the polymer solid electrolyte may be polyether (polyethylene oxide), polysiloxane, polycarbonate, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, a single ion polymer, polyionic liquid-lithium salt, cellulose, and the like.

[0102] 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 phosphide, germanium argentum sulfide), amorphous sulfide) and one or more of a halide solid electrolyte, a nitride solid electrolyte and a hydride solid electrolyte.

[0103] As an example, the composite solid electrolyte is formed by adding an inorganic solid electrolyte filler to a polymer solid electrolyte.

[0104] 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.

[0105] In some embodiments, the electrode assembly is a laminate structure.

[0106] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets may be provided respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets may be alternately stacked.

[0107] 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.

[0108] As an example, both the positive electrode sheet and the negative electrode sheet are folded to form a plurality of folded sections that are stacked.

[0109] As an example, a plurality of separators may be provided, each of which is provided between any adjacent positive electrode sheets or negative electrode sheets.

[0110] As an example, the separator may be disposed continuously, and may be disposed between any adjacent positive electrode sheets or negative electrode sheets by folding or winding.

[0111] In some embodiments, the shape of the electrode assembly can be cylindrical, flat, or polygonal.

[0112] In some embodiments, the electrode assembly is provided with tabs, which can lead current out of the electrode assembly. The tabs include a positive tab and a negative tab.

[0113] In some embodiments, the battery cell may include a housing. The housing is used to encapsulate components such as the electrode assembly and the electrolyte. The housing may be a steel housing, an aluminum housing, a plastic housing (such as polypropylene), a composite metal housing (such as a copper-aluminum composite housing), or an aluminum-plastic film.

[0114] 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, a polygonal battery, such as a hexagonal battery, etc. There is no special limitation in this application.

[0115] 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.

[0116] 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.

[0117] In some embodiments, the battery may be a battery pack, which includes a case and battery cells, wherein the battery cells or battery modules are accommodated in the case.

[0118] 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.

[0119] In some embodiments, the battery may be an energy storage device, which includes an energy storage container, an energy storage cabinet, and the like.

[0120] The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery reliability must also be considered.

[0121] The pressure relief mechanism on the battery cell has an important impact on the reliability of the battery cell. For example, when a short circuit or overcharge occurs, thermal runaway may occur inside the battery cell, causing a sudden increase in pressure. In this case, the pressure relief mechanism can be activated to release the internal pressure to the outside, thereby reducing the risk of battery cell explosion and fire.

[0122] The pressure relief mechanism refers to an element or component that is activated to release internal gas when the internal pressure or temperature of the battery cell reaches a predetermined threshold. The threshold design varies according to different design requirements. The threshold may depend on one or more materials of the positive electrode sheet, negative electrode sheet, electrolyte and separator in the battery cell.

[0123] The pressure relief mechanism may be in the form of an explosion-proof valve, an air valve, a pressure relief valve or a safety valve, and may specifically be a pressure-sensitive element or structure, that is, when the internal pressure of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action or a weak area provided in the pressure relief mechanism ruptures, thereby forming an opening or channel for internal pressure relief. Alternatively, the pressure relief mechanism may also be a temperature-sensitive element or structure, that is, when the internal temperature of the battery cell reaches a predetermined threshold, the pressure relief mechanism performs an action, thereby forming an opening or channel for internal pressure relief.

[0124] The "actuation" mentioned in this application means that the pressure relief mechanism is in action or activated to a certain state, so that the internal pressure of the battery cell can be released. The action produced by the pressure relief mechanism may include but is not limited to: at least a part of the pressure relief mechanism is ruptured, broken, torn or opened, etc. When the pressure relief mechanism is actuated, the high-temperature and high-pressure substances inside the battery cell will be discharged from the actuated part as emissions. In this way, the battery cell can be depressurized under controllable pressure, thereby avoiding potential more serious accidents.

[0125] The emissions from the battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode sheets, fragments of separators, high-temperature and high-pressure gases produced by the reaction, flames, and the like.

[0126] There are usually multiple battery cells arranged in a battery. When a battery cell experiences thermal runaway, the high-temperature substances (such as high-temperature gas, high-temperature particles, etc.) inside the battery cell are released after the pressure relief mechanism is activated; when the released high-temperature gas flows through the normal battery cell, it may heat the pressure relief mechanism of the normal battery cell, thereby causing the risk of cracking and failure of the pressure relief mechanism of the normal battery cell, causing the normal battery cell to fail, thermal runaway and other problems, affecting the reliability of the battery.

[0127] 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, thereby reducing the heat conducted to the pressure relief mechanism, reducing the risk of cracking and failure of the pressure relief mechanism, and improving the reliability of the battery cell.

[0128] The battery cells described in the embodiments of the present application are suitable for use in batteries and electrical devices using the batteries.

[0129] The battery cells, batteries and electrical devices disclosed in the embodiments of the present application can be used in electrical devices that use batteries as power sources or various energy storage systems that use batteries as energy storage elements. Electrical devices can be, but are not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0130] For the convenience of description, the following embodiments are described by taking the electric device as a vehicle as an example.

[0131] Figure 1 A schematic diagram of the structure of a vehicle provided for some embodiments of the present application.

[0132] like Figure 1 As shown, a battery 2 is disposed inside the vehicle 1, and the battery 2 may be disposed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may be used as an operating power source for the vehicle 1.

[0133] The vehicle 1 may further include a controller 3 and a motor 4 , wherein the controller 3 is used to control the battery 2 to supply power to the motor 4 , for example, to meet the power requirements of starting, navigating, and driving the vehicle 1 .

[0134] In some embodiments of the present application, the battery 2 can not only serve as an operating power source for the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0135] Figure 2 Schematic diagram of an explosion of a battery provided in some embodiments of the present application. Figure 2 As shown, the battery 2 includes a box body 5 and a battery cell 6 , and the battery cell 6 is accommodated in the box body 5 .

[0136] The box 5 is used to accommodate the battery cell 6, and the box 5 can be of various structures. In some embodiments, the box 5 can include a first box portion 5a and a second box portion 5b, the first box portion 5a and the second box portion 5b cover each other, and the first box portion 5a and the second box portion 5b jointly define a storage space 5c for accommodating the battery cell 6. The second box portion 5b can be a hollow structure with one end open, the first box portion 5a is a plate-like structure, and the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c; the first box portion 5a and the second box portion 5b can also be hollow structures with one side open, and the open side of the first box portion 5a covers the open side of the second box portion 5b to form a box 5 with a storage space 5c. Of course, the first box portion 5a and the second box portion 5b can be of various shapes, such as a cylinder, a cuboid, etc.

[0137] In order to improve the sealing performance after the first box body part 5a and the second box body part 5b are connected, a sealing member, such as a sealant, a sealing ring, etc., may also be provided between the first box body part 5a and the second box body part 5b.

[0138] 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.

[0139] In the battery 2, there can be one or more battery cells 6. If there are more than one battery cell 6, the battery cells 6 can be connected in series, in parallel or in mixed connection. Mixed connection means that the battery cells 6 are both connected in series and in parallel. The battery cells 6 can be directly connected in series, in parallel or in mixed connection, and then the whole formed by the battery cells 6 can be accommodated in the box 5; of course, the battery cells 6 can also be connected in series, in parallel or in mixed connection to form a battery module, and then the battery modules can be connected in series, in parallel or in mixed connection to form a whole, and then accommodated in the box 5.

[0140] Figure 3 An exploded schematic diagram of a battery cell provided in some embodiments of the present application; Figure 4 A schematic cross-sectional view of a battery cell provided in some embodiments of the present application; Figure 5 for Figure 4 An enlarged schematic diagram at the circle frame; Figure 6 for Figure 5 Enlarged schematic diagram at the box; Figure 7 for Figure 6 Enlarged diagram of the circle.

[0141] Reference Figures 3 to 7An 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 arranged in the housing 20), and at least a portion of the electrode assembly 10 is accommodated in the housing 20.

[0142] The housing 20 is a hollow structure, and a space for accommodating the electrode assembly 10 and the electrolyte is formed therein. The shape of the housing 20 can be determined according to the specific shape of the electrode assembly 10. For example, if the electrode assembly 10 is a rectangular parallelepiped structure, a rectangular housing can be selected; if the electrode assembly 10 is a cylindrical structure, a cylindrical housing can be selected.

[0143] 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.

[0144] 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.

[0145] The housing 21 and the end cap 22 may be independent components. For example, an opening may be provided on the housing 21, and the end cap 22 may cover the opening to form an internal cavity of the battery cell 6.

[0146] The shell 21 can be in various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism shape, etc. Specifically, the shape of the shell 21 can be determined according to the specific shape and size of the electrode assembly 10. The shell 21 can be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc., and the embodiment of the present application does not impose any special restrictions on this.

[0147] The shape of the end cap 22 can be adapted to the shape of the shell 21 to match the shell 21. The material of the end cap 22 can be the same as or different from the material of the shell 21. Optionally, the end cap 22 can be made of a material with a certain hardness and strength (for example, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc.), so that the end cap 22 is not easily deformed when squeezed and collided, so that the battery cell 6 can have a higher structural strength and the reliability performance can also be improved.

[0148] The end cover 22 is connected to the housing 21 by welding, bonding, clamping or other methods.

[0149] The housing 21 may be open at one end or at both ends. In some examples, the housing 21 may be a structure with an opening at one end, and an end cap 22 is provided and covers the housing 21. In other examples, the housing 21 may be a structure with openings at both ends, and two end caps 22 are provided, and the two end caps 22 cover the two openings of the housing 21 respectively.

[0150] The electrode terminal 30 may be used to be electrically connected to the electrode assembly 10 to output or input electrical energy of the battery cell 6 .

[0151] 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.

[0152] As an example, the electrode assembly 10 includes a positive electrode sheet and a negative electrode sheet. The portions of the positive electrode sheet and the negative electrode sheet having active materials constitute the main body of the electrode assembly 10, and the portions of the positive electrode sheet and the negative electrode sheet not having active materials each constitute a tab. The tab may include a positive tab and a negative tab. The positive tab and the negative tab may be located together at one end of the main body or respectively at both ends of the main body.

[0153] 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.

[0154] In some embodiments, the battery cell 6 includes a shell 20 and a pressure relief mechanism 40 , the shell 20 includes a wall portion 211 , the pressure relief mechanism 40 is disposed on the wall portion 211 , and the pressure relief mechanism 40 can be actuated to release the gas in the shell 20 when the internal pressure or temperature of the battery cell 6 reaches a threshold.

[0155] As an example, the wall portion 211 may be the end cover 22 or a wall of the housing 21 .

[0156] As an example, the shape of the wall portion 211 may be circular, rectangular, oval, or other shapes.

[0157] In some examples, the pressure relief mechanism 40 and the wall portion 211 are independently formed components, and the two can be connected by welding, bonding or other methods. For example, the wall portion 211 is provided with a pressure relief hole, and the pressure relief hole passes through the wall portion 211. The pressure relief mechanism 40 is installed on the wall portion 211 and covers the pressure relief hole to separate the space on both sides of the wall portion 211. In an alternative embodiment, the pressure relief mechanism 40 and the wall portion 211 can also be an integrally formed structure.

[0158] The threshold value design varies according to different design requirements. The threshold value may depend on one or more materials of the positive electrode, negative electrode, electrolyte and separator in the battery cell 6.

[0159] When the internal pressure or temperature of the battery cell 6 reaches a threshold, the pressure relief mechanism 40 is activated to release the gas in the housing 20, thereby releasing the internal pressure of the battery cell 6. As an example, when the pressure relief mechanism 40 is activated, other high-temperature substances such as particles, debris, etc. can also be released.

[0160] 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 .

[0161] 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 .

[0162] As an example, when the battery cell 6 is in thermal runaway, as the gas in the housing 20 continues to accumulate, the internal pressure of the housing 20 may reach or even exceed the pressure threshold. When the internal pressure of the housing 20 reaches the threshold, the pressure relief mechanism 40 is actuated and forms an exhaust channel to connect the internal space of the housing 20 with the external space, and the gas inside the housing 20 may be discharged through the exhaust channel, thereby reducing the risk of explosion of the battery cell 6.

[0163] As an example, when the electrolyte and active material react and release heat quickly, the internal temperature of the housing 20 will rise, and the temperature rise will also cause the internal pressure of the housing 20 to rise. When the internal temperature of the housing 20 reaches a threshold, the pressure relief mechanism 40 can be actuated under the action of temperature and pressure to form an exhaust channel, so that the internal space of the housing 20 is connected with the external space, and the gas inside the housing 20 can be discharged through the exhaust channel, thereby reducing the risk of explosion of the battery cell 6.

[0164] 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 .

[0165] 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.

[0166] In the thickness direction Z of the wall 211 , at least part of the protection member 50 is located on the side of the pressure relief mechanism 40 away from the electrode assembly 10 . In the thickness direction Z of the wall 211 , the projection of the protection member 50 at least partially overlaps with the projection of the pressure relief mechanism 40 .

[0167] In the thickness direction Z, the protection member 50 may completely cover the pressure relief mechanism 40 , or may only cover a portion of the pressure relief mechanism 40 .

[0168] 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.

[0169] The protection component 50 may be connected to the wall portion 211 , and may also be connected to the pressure relief mechanism 40 .

[0170] As an example, when the pressure relief mechanism 40 is actuated, the protective member 50 may be broken, shattered, opened, flew out, or perform other actions under the internal pressure of the battery cell 6 to reduce the barrier of the protective member 50 to the gas.

[0171] When thermal runaway occurs in the battery cell 6, the pressure relief mechanism 40 is activated and the gas in the housing 20 is released to the outside to reduce the risk of explosion and 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 it 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 it is not easy to deform or melt through under high temperature, 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 the battery cell 6.

[0172] 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 with relatively low strength, which is a portion of the pressure relief mechanism 40 that is easily broken, shattered, torn or opened. Exemplarily, the strength of the pressure relief mechanism 40 is less than the strength of the portion of the pressure relief mechanism 40 close to the weak portion 41.

[0173] In some examples, the present application may provide 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 is performed on a predetermined area of ​​the pressure relief mechanism 40, and the thinned portion of the pressure relief mechanism 40 forms the weak portion 41. In other examples, a material process may be performed on a predetermined area of ​​the pressure relief mechanism 40, so that the strength of the area is weaker than that of other areas. In other words, the area is the weak portion 41.

[0174] The weak portion 41 can be ruptured when the internal pressure or temperature of the battery cell 6 reaches a threshold value to release the gas in the housing 20 .

[0175] In some embodiments, the pressure relief mechanism 40 and the wall portion 211 are independently formed components, and the two 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.

[0176] 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 .

[0177] The protective component 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 .

[0178] Optionally, in the thickness direction Z, the protective member 50 completely covers the weak portion 41 .

[0179] 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 .

[0180] 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 .

[0181] 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.

[0182] As an example, the shape of the receiving recess 213 may be a columnar shape, a cone shape, a step shape or other shapes.

[0183] 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 received in its entirety in the receiving recess 213, or may be received in its entirety in the receiving recess 213.

[0184] 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 .

[0185] In some embodiments, the protective member 50 is completely received in the receiving recess 213. In the thickness direction Z, the surface of the protective member 50 that faces away from the pressure relief mechanism 40 does not exceed the outer surface 212.

[0186] The embodiment of the present application can further improve the space utilization and energy density of the battery cell 6. In addition, the protective member 50 is completely accommodated in the accommodating recess 213, which can reduce the risk of friction between the protective member 50 and the external structure during the production, transportation and use of the battery cell 6, and improve the reliability of the protective member 50.

[0187] In some embodiments, a bottom wall 214 of the accommodating recess 213 is provided with a through hole 215 , and the pressure relief mechanism 40 is accommodated in the accommodating recess 213 , connected to the bottom wall 214 and covers the through hole 215 .

[0188] When the pressure relief mechanism 40 is activated, a gas exhaust passage 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 gas exhaust passage.

[0189] In some embodiments, in the thickness direction Z, the protective member 50 is spaced apart from the pressure relief mechanism 40 .

[0190] 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.

[0191] In some embodiments, the accommodating recess 213 is stepped, a step surface 213 a is provided on a side wall of the accommodating recess 213 , and the protective member 50 is connected to the step surface 213 a , thereby being spaced apart from the pressure relief mechanism 40 .

[0192] In some embodiments, in the thickness direction Z, there are no other components between the protective member 50 and the pressure relief mechanism 40 .

[0193] 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. No other solid components are provided between the protective member 50 and the pressure relief mechanism 40, which can reduce the obstruction to the gas when the pressure relief mechanism 40 is actuated, and can also avoid the heat conduction of the solid structure between the protective member 50 and the pressure relief mechanism 40 to a certain extent, thereby reducing the heat transfer rate between the protective member 50 and the pressure relief mechanism 40.

[0194] 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≥0.01 mm 2 .

[0195] The larger t is, the lower the temperature of the surface of the protective member 50 facing the pressure relief mechanism 40 is when the 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 the high-temperature substance impacts the protective member 50, and the more heat the protective member 50 radiates toward the pressure relief mechanism 40.

[0196] The larger D is, the longer the heat transfer path between the protective component 50 and the pressure relief mechanism 40 is when the high-temperature material impacts the protective component 50 ; the smaller D is, the shorter the heat transfer path between the protective component 50 and the pressure relief mechanism 40 is.

[0197] In the present embodiment, t×D is defined as greater than or equal to 0.01 mm. 2 , when a high-temperature substance impacts 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 .

[0198] 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 .

[0199] Optionally, t×D≥0.05mm 2 . Optionally, t×D≥0.1mm 2 .

[0200] In some embodiments, t is 0.05 mm-0.4 mm.

[0201] In the embodiment of the present application, t is limited to be greater than or equal to 0.05 mm, so that when a high-temperature substance impacts the protective member 50, the heat radiated from the protective member 50 to the pressure relief mechanism 40 can be reduced, and the temperature rise of the pressure relief mechanism 40 can be reduced. The larger t is, the larger the space and weight occupied by the protective member 50 will be; by limiting t to be less than or equal to 0.4 mm, the space and weight occupied by the protective member 50 can be reduced, and the energy density of the battery cell 6 can be increased, provided that the protection requirements of the protective member 50 meet the requirements.

[0202] 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.

[0203] 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 under the premise that the protection requirements of the protective member 50 meet the needs.

[0204] 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 higher melting point and is not easily melted when subjected to thermal shock, so that the protective member 50 has better thermal shock resistance and reduces the risk of the protective member 50 being melted through.

[0205] In some embodiments, the melting point of the protective member 50 is greater than or equal to 1000°C.

[0206] In some embodiments, the material of the protective member 50 includes one of mica, rubber, ceramic or polyimide.

[0207] 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.

[0208] 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.

[0209] For example, using a film tensile strength tester, at an ambient temperature of 150°C, a gradually increasing tensile load is applied to the length direction of a standard sample to deform it until it breaks. The maximum tensile stress required for the sample to break is the tensile strength. Tensile strength can also be called tensile strength.

[0210] The greater the tensile strength of the protective member 50, the more difficult it is to rupture when the pressure relief mechanism 40 is actuated. In the embodiment of the present application, the tensile strength of the protective member 50 at 150° C. is set to be less than or equal to 350 MPa, so that the protective member 50 can be ruptured in time when the pressure relief mechanism 40 is actuated, thereby improving the exhaust efficiency.

[0211] The smaller the tensile strength of the protective member 50, the greater the deformation of the protective member 50 when the external air pressure fluctuates; as the use time increases, the protective member 50 is more likely to be fatigue-deformed. In the embodiment of the present application, 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.

[0212] 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.

[0213] In some embodiments, the protective member 50 has a tensile strength of 170 MPa to 250 MPa at 150°C.

[0214] In some embodiments, the housing 20 includes a shell 21 and an end cover 22 . One end of the shell 21 has an opening. The end cover 22 is connected to the shell 21 and covers the opening.

[0215] Exemplarily, when the battery cell 6 is used upright, the end cap 22 is located above the electrode assembly 10 along the direction of gravity. When the battery cell 6 is used inverted, the end cap 22 is located below the electrode assembly 10 along the direction of gravity.

[0216] In some embodiments, the housing 21 includes a wall portion 211, which is opposite to the end cap 22. By disposing 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.

[0217] In some embodiments, a thickness direction Z of the wall portion 211 is parallel to the gravity direction, and the wall portion 211 is located at a lower side of the electrode assembly 10 in the gravity direction.

[0218] 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, the gas can be ejected downward, thereby reducing exhaust resistance and improving exhaust efficiency.

[0219] 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.

[0220] Figure 8 for Figure 5 An enlarged schematic diagram at the circle frame; Fig. 9 A top view of a protective member and a connecting layer of a battery cell provided in some embodiments of the present application.

[0221] Please refer to Figures 6 to 9 In some embodiments, the battery cell 6 further includes a connection layer 60 , and the protection member 50 is connected to the wall portion 211 through the connection layer 60 .

[0222] The connection layer 60 can be connected to the wall portion 211 and the protective member 50 in a variety of ways. In some examples, the connection layer 60 can adhere the protective member 50 to the wall portion 211. In other examples, the connection layer 60 is welded to the protective member 50 and the wall portion 211.

[0223] In some embodiments, the connection layer 60 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold value to disengage at least a portion of the guard member 50 from the wall portion 211 .

[0224] 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.

[0225] At least a portion of the protection member 50 is separated from the wall portion 211, which may mean that at least a portion of the protection member 50 is no longer constrained by the wall portion 211 and can deviate from the initial set position.

[0226] “Actuation of the connection layer 60” means that the connection layer 60 is moved or activated to a certain state, so that at least part of the protective member 50 is separated from the wall portion 211. The movement of the connection layer 60 may include but is not limited to: at least part of the connection layer 60 is disconnected from the wall portion 211, at least part of the connection layer 60 is disconnected from the protective member 50, the connection layer 60 is torn, and the like.

[0227] 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 portion 211 , thereby releasing the internal gas of the battery cell 6 and reducing the internal pressure and temperature of the battery cell 6 .

[0228] In some embodiments, the connection layer 60 can be actuated when the internal pressure or temperature of the battery cell 6 reaches a threshold value, so that the entire protective member 50 is separated from the wall portion 211. When a short circuit, overcharge, etc. occurs, the pressure relief mechanism 40 is actuated, and the protective member 50 can be separated from the wall portion 211 and no longer blocks the pressure relief mechanism 40, thereby increasing the gas release rate and reducing the risk of explosion of the battery cell 6.

[0229] 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 in the housing 20 .

[0230] In some embodiments, the connecting layer 60 includes a glue layer.

[0231] 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.

[0232] When the battery cell 6 thermally runs away, the heat can be transferred to the connection layer 60 , and the connection layer 60 softens, so that the protection member 50 can be separated from the wall portion 211 in time when the pressure relief mechanism 40 is actuated.

[0233] 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 .

[0234] By disposing the connection layer 60 in the peripheral area of ​​the protective component 50 , the amount of the connection layer 60 can be saved and the risk of connection between the connection layer 60 and the pressure relief mechanism 40 can be reduced.

[0235] In some embodiments, in the thickness direction Z, the connection layer 60 is entirely located between the wall portion 211 and the protection member 50 .

[0236] 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 .

[0237] During the charging and discharging process of the battery cell 6, the internal air pressure of the battery cell 6 will fluctuate slightly. When the internal air pressure of the battery cell 6 fluctuates, the pressure relief mechanism 40 may bulge outward. The embodiment of the present application provides a connecting flow channel 80 to connect the escape space 70 with the external environment, thereby reducing the pressure change of the escape space 70 when the pressure relief mechanism 40 bulges and reducing the deformation of the protective member 50.

[0238] In addition, during the production process of the battery cell 6 , the air tightness of the pressure relief mechanism 40 can also be detected through the connecting flow channel 80 and the escape space 70 .

[0239] 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 component 50 form a connecting flow channel 80 .

[0240] Fig.10 A top view of a protective member and a connecting layer of a battery cell provided in some other embodiments of the present application; Fig.11 for Fig.10 A schematic cross-sectional view of the protective component and the connecting layer shown.

[0241] like Fig.10 and Fig.11 As shown, in some embodiments, the communication flow passage 80 includes a groove 51 provided on a surface of the protection member 50 facing the pressure relief mechanism 40 .

[0242] The 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 .

[0243] In some embodiments, in the thickness direction Z, the connection layer 60 and the groove 51 do not overlap, so as to reduce the risk of the connection layer 60 filling into the groove 51 .

[0244] Fig.12 A schematic diagram of a battery provided for some embodiments of the present application; Fig.13 A schematic cross-sectional view of a battery provided in some embodiments of the present application; Fig.14 for Fig.13 Enlarged schematic diagram at the box; Fig.15 for Fig.14 Enlarged diagram of the circle.

[0245] Reference Figures 12 to 15 The 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.

[0246] In some embodiments, the battery 2 further includes a box body 5, and a plurality of battery cells 6 are accommodated in the box body 5. The box body 5 includes a first box wall 5d, and a wall portion 211 is provided at one end of the housing 20 facing the first box wall 5d. A channel 5e is provided on the inner side of the first box wall 5d. In the thickness direction Z, the projection of the pressure relief mechanism 40 of the plurality of 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.

[0247] When thermal runaway occurs in the battery cell 6, the pressure relief mechanism 40 is activated and releases the gas in the housing 20 to the outside into the channel 5e; the channel 5e guides the high-temperature gas to flow so as to discharge the high-temperature gas to the outside of the box 5, thereby reducing the risk of explosion of the battery 2. During the flow of the high-temperature gas along the channel 5e, the protective member 50 can separate the high-temperature gas from the pressure relief mechanism 40, reduce the heat conducted to the pressure relief mechanism 40, reduce the risk of cracking and failure of the pressure relief mechanism 40, simplify the continuous deterioration of thermal runaway, and improve the reliability of the battery 2.

[0248] 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 the gas in the housing 20; the embodiment of the present application can reduce the risk of the first box wall 5d interfering with the protective member 50, so that the protective member 50 can smoothly enter the channel 5e.

[0249] 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 .

[0250] 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 .

[0251] The embodiment of the present application can reduce the problem of the first box wall 5d interfering with 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.

[0252] According to some embodiments of the present application, the present application further provides an electric device, including the battery 2 of any of the above embodiments, the battery 2 is used to provide electric energy for the electric device. The electric device can be any of the above devices or systems using the battery 2.

[0253] Reference Figures 3 to 8An 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 .

[0254] The electrode assembly 10 is accommodated in a housing 20 .

[0255] The housing 20 includes a housing 21 and an end cap 22. One end of the housing 21 has an opening. The end cap 22 is connected to the housing 21 and covers 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 gravity direction, and the wall portion 211 is located at the lower side of the electrode assembly 10 in the gravity direction.

[0256] The wall portion 211 has an outer surface 212 on the side facing away from 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. A through hole 215 is provided on the bottom wall 214 of the receiving recess 213, and the pressure relief mechanism 40 is received in the receiving recess 213, connected to the bottom wall 214 and covers the through hole 215.

[0257] 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.

[0258] A step surface 213 a is provided on the side wall of the accommodating recess 213 , and the connection 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 .

[0259] 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 value. The connection layer 60 can be actuated 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.

[0260] The melting point of the protective member 50 is greater than 500° C. Optionally, the protective member 50 is a mica board.

[0261] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: a housing, including a wall portion; 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, characterized in that: 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, characterized in that: The protection member is completely accommodated in the accommodation recess.

4. The battery cell according to claim 2, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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 according to claim 1, characterized in that: The battery cell further includes a connection layer, and the protection 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, characterized in that: The connecting layer includes an adhesive layer.

11. The battery cell according to claim 9, characterized in that: 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 9-11, characterized in that: 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, characterized in that: 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 claim 1, characterized in that: The melting point of the protective member is greater than or equal to 500°C.

15. The battery cell according to claim 1, characterized in that: The material of the protective component includes one of mica, rubber, ceramic or polyimide.

16. The battery cell according to claim 1, characterized in that: 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 claim 1, characterized in that: The battery cell further includes 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 claim 1, characterized in that: 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, characterized in that: The invention comprises a plurality of battery cells according to any one of claims 1 to 18.

20. The battery according to claim 19, characterized in that The battery further comprises a box, wherein the plurality of battery cells are accommodated in the box; 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, characterized in that 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, characterized in that 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, characterized in that: Comprising a battery according to any one of claims 19 to 22, the battery is used to provide electrical energy.

Images