Rechargeable battery and electric apparatus

Abstract

The present application relates to a rechargeable battery and an electric apparatus. Provided in the embodiments of the present application is a rechargeable battery, comprising: a housing, an electrode assembly, an overcharge protection mechanism, and an electrolyte. The housing has a first face. The electrode assembly is arranged inside the housing; the overcharge protection mechanism is arranged on the first face; and the electrolyte comprises a gas-generating agent. The gas-generating agent can react and generate gas when a response voltage is reached; and the rechargeable battery can trigger the overcharge protection mechanism by means of the gas when an overcharge voltage reaches the response voltage. In the technical solution, by means of adding the gas-generating agent to the electrolyte, a polymerization reaction occurs when the overcharge voltage reaches the response voltage, generating the gas and thus triggering the overcharge protection mechanism, so that a short-circuit component of the rechargeable battery acts earlier, advancing the activation of short-circuit protection, greatly reducing thermal runaway of the rechargeable battery that is caused by a large amount of heat generated by means of the decomposition of main materials of the battery, and facilitating a reduction in the probability of the thermal runaway of the rechargeable battery.

Description

Secondary battery and power consuming device Cross-reference to related applications

[0001] This application claims priority to the Chinese Patent Application No. 202411026351.X, filed on July 29, 2024, and entitled "Secondary battery and power consuming device", the contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to a secondary battery and a power consuming device. BACKGROUND

[0003] In recent years, with the development of lithium ion secondary battery technology, lithium ion secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Since lithium ion secondary batteries have made great progress, higher requirements have been placed on their thermal runaway probability. SUMMARY

[0004] The purpose of the present application is to provide a secondary battery and a power consuming device.

[0005] Embodiments of the present application are implemented as follows:

[0006] In a first aspect, embodiments of the present application provide a secondary battery, comprising:

[0007] a housing having a first surface;

[0008] an electrode assembly disposed in the housing;

[0009] an overcharge protection mechanism disposed on the first surface; and

[0010] an electrolyte comprising a gas generating agent; the gas generating agent is capable of reacting and generating gas when reaching a response voltage;

[0011] The secondary battery can trigger the overcharge protection mechanism by gas when the overcharge voltage reaches the response voltage.

[0012] The above technical solution can cause a polymerization reaction and generate gas when the overcharge voltage reaches the response voltage by adding a gas generating agent to the electrolyte, and trigger the overcharge protection mechanism; thereby causing the short-circuit component or the open-circuit component of the secondary battery to act earlier, advancing the time of short-circuit or open-circuit protection, greatly reducing the decomposition of the battery main material to generate a large amount of heat to trigger the secondary battery thermal runaway, and more favorably reducing the probability of secondary battery thermal runaway.

[0013] In some optional embodiments, the response voltage is greater than the upper limit of the working voltage of the secondary battery.

[0014] In the technical solution, the response voltage is greater than the upper limit of the working voltage of the secondary battery, so that the protection mechanism can be triggered in time to cut off the charging circuit when overcharging occurs, thereby reducing the risk of thermal runaway of the battery caused by decomposition of the main material of the secondary battery and generation of a large amount of heat.

[0015] In some optional embodiments, the response voltage is 4.5V-5.475V.

[0016] In the technical solution, the response voltage is 4.5V-5.475V, so that the overcharge protection mechanism can be triggered in time when the secondary battery generates a polymerization reaction and generates gas when overcharging occurs.

[0017] In some optional embodiments, the gas generating agent includes one or more of the aromatic compounds having the structure shown below:

[0018] In the technical solution, the aromatic compound having the structure shown above can generate a polymerization reaction and generate gas when the overvoltage reaches the response voltage, and trigger the overcharge protection mechanism.

[0019] In the technical solution, the aromatic compound having the structure shown above can generate a polymerization reaction and generate gas when the overvoltage reaches the response voltage, and trigger the overcharge protection mechanism.

[0020] In some optional embodiments, the gas generating agent includes at least one of biphenyl, cyclohexylbenzene, or tert-butylbenzene.

[0021] In some optional embodiments, the mass fraction of the gas generating agent in the electrolyte is 0.5%-10%.

[0022] In the technical solution, the mass fraction of the gas generating agent in the electrolyte is 0.5%-10%, which can effectively generate gas, generate a polymerization reaction and generate gas when the overvoltage reaches the response voltage, and trigger the overcharge protection mechanism, and can effectively shorten the time of triggering the overcharge protection mechanism.

[0023] In some optional embodiments, the mass fraction of the gas generating agent in the electrolyte is 1%-5%.

[0024] In the technical solution, the mass fraction of the gas generating agent in the electrolyte is further limited to 1%-5%, which can effectively generate gas, generate a polymerization reaction and generate gas when the overvoltage reaches the response voltage, and trigger the overcharge protection mechanism, and can further effectively shorten the time of triggering the overcharge protection mechanism.

[0025] In some optional embodiments, the secondary battery further includes a first electrode terminal, and the first electrode terminal is insulated from the first surface.

[0026] The overcharge protection mechanism includes a first deformation member electrically connected to the first surface, the first deformation member being configured to deform under the action of the gas pressure to contact the first electrode terminal.

[0027] In some alternative embodiments, the first electrode terminal includes a first conductive member and a first pole, the first conductive member and the first pole being connected to each other, the first conductive member being disposed outside the first surface and insulated from the first surface, and the first pole being electrically connected to the electrode assembly.

[0028] The first deformation member is configured to deform under the action of the gas pressure to contact the first conductive member, so as to electrically connect the first pole to the first surface.

[0029] In some alternative embodiments, the secondary battery further includes a first insulating member, at least a portion of the first insulating member being disposed between the first conductive member and the first surface.

[0030] In some alternative embodiments, the first insulating member has an electrical resistance value greater than or equal to 200 megaohms.

[0031] In some alternative embodiments, the first surface has a first electrode lead-out hole, and the first pole is disposed through the first electrode lead-out hole.

[0032] The secondary battery further includes a second insulating member, at least a portion of the second insulating member being disposed between a hole wall of the first electrode lead-out hole and the first pole.

[0033] In some alternative embodiments, an outer peripheral surface of the first pole is formed with a first flange, and along a thickness direction of the first surface, a portion of the second insulating member is located between the first flange and an inner side surface of the first surface.

[0034] In some alternative embodiments, the second insulating member has an electrical resistance value greater than or equal to 200 megaohms.

[0035] In some alternative embodiments, a surface of the first conductive member facing the first surface is provided with a first protrusion for contacting the first deformation member.

[0036] In some alternative embodiments, the first deformation member includes a first contact portion, a first deformation portion, and a first connecting portion, the first deformation portion being disposed on an outer peripheral surface of the first contact portion, the first connecting portion being disposed on an end portion of the first deformation portion away from the first contact portion, the first connecting portion being connected to the first surface, and the first deformation portion being configured to deform under the action of the gas pressure to cause the first contact portion to contact the first conductive member.

[0037] In some alternative embodiments, a thickness of the first deformation portion is less than a thickness of the first connecting portion, and the thickness of the first deformation portion is less than a thickness of the first contact portion.

[0038] In some alternative embodiments, the first deformation member has a thickness of 0.1 mm to 0.5 mm.

[0039] In some alternative embodiments, the secondary battery further comprises:

[0040] a second electrode terminal disposed in the first face in an insulating manner;

[0041] a second deformation member electrically connected to the first face, the second deformation member being configured to deform to contact the second electrode terminal under the action of air pressure.

[0042] In some alternative embodiments, the second electrode terminal is a negative electrode terminal, and a minimum pressure value at which the second deformation member deforms is greater than a minimum pressure value at which the first deformation member deforms.

[0043] In some alternative embodiments, the electrode assembly comprises a positive electrode tab, the positive electrode tab comprising a positive active material, and the positive active material comprising a lithium-containing phosphate with an olivine structure.

[0044] In a fourth aspect, an embodiment of the present application provides a power consumption device, comprising the secondary battery provided in any of the embodiments of the first aspect. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0046] FIG. 1 is a perspective exploded view of a battery cell in some embodiments of the present application;

[0047] FIG. 2 is an internal structure diagram of a partial structure of a battery cell in some embodiments of the present application;

[0048] FIG. 3 is a perspective exploded view of a partial structure of a battery cell in some embodiments of the present application;

[0049] FIG. 4 is a schematic diagram of a first face, a first electrode terminal and a first deformation member in some embodiments of the present application;

[0050] FIG. 5 is a schematic diagram of a first deformation member in some embodiments of the present application;

[0051] FIG. 6 is a schematic diagram of a first face, a second electrode terminal and a second deformation member in some embodiments of the present application;

[0052] FIG. 7 is a schematic diagram of a battery module in some embodiments of the present application;

[0053] Figure 8 is a schematic diagram of the battery pack in some embodiments of this application;

[0054] Figure 9 is an exploded view of the battery pack in some embodiments of this application shown in Figure 8;

[0055] Figure 10 is a schematic diagram of an electrical device in which a secondary battery is used as a power source according to some embodiments of this application.

[0056] icon:

[0057] 10-Battery cell; 11-Casing; 110-Shell; 111-First surface; 1110-First electrode lead-out hole; 1111-First through hole; 1112-Second electrode lead-out hole; 1113-Second through hole; 12-Electrode assembly; 120-First tab; 121-First adapter; 122-Second tab; 123-Second adapter; 13-Overcharge protection mechanism; 130-First deformable part; 1300-First contact part; 1301-First deformable part; 1302-First connecting part; 131-Second deformable part; 14-First electrode terminal; 140-First conductive part; 1400-First protrusion; 141-First pole post; 1410-First flange; 150-First insulating part; 151-Second insulating part; 152-Third insulating part; 153-Fourth insulating part; 16-Second electrode terminal; 160-Second conductive part; 1600-Second protrusion; 161-Second pole post; z-Thickness direction of the first surface; 1-Battery pack; 2-Upper housing; 3-Lower housing; 4-Battery module. Detailed Implementation

[0058] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein 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 specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0060] In the description of the embodiments of this application, the technical terms "first", "second", etc. are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0061] In the description of the embodiments of this application, the technical terms "inner" and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0062] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0063] In this document, the term "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 throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0064] 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 height, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall height, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0065] To reduce the probability of thermal runaway in secondary batteries due to overcharging, short-circuit or open-circuit components are often installed for overcharge protection. These components can be activated by pressure, thereby connecting the battery to the external circuit via the electrode assembly. However, the response time of internal battery pressure to heat / voltage activation is slow, leading to a high accumulated internal temperature. Even if the short-circuit component activates at this point, thermal runaway may still occur.

[0066] Based on this, the first aspect of the embodiments of this application provides a secondary battery, comprising:

[0067] The outer shell has a first surface;

[0068] Electrode assembly, housed within the housing;

[0069] Overcharge protection mechanism, located on the first side; and

[0070] The electrolyte includes a gas-generating agent; the gas-generating agent is capable of reacting and producing gas when the response voltage is reached;

[0071] The secondary battery can trigger the overcharge protection mechanism via gas when the overcharge voltage reaches the response voltage.

[0072] In the above technical solution, by adding a gas-generating agent to the electrolyte, a polymerization reaction can occur and gas can be generated when the overcharge voltage reaches the response voltage, triggering the overcharge protection mechanism. This allows the short-circuit or open-circuit components of the secondary battery to act earlier, advancing the short-circuit or open-circuit protection time and greatly reducing the thermal runaway of the secondary battery caused by the decomposition of the main battery material and generating a large amount of heat. This is more conducive to reducing the probability of thermal runaway of the secondary battery.

[0073] The term "secondary battery" as used in this article refers to a single battery cell, battery module, or battery pack; "electrode assembly" includes the positive electrode, negative electrode, and separator. The positive electrode, negative electrode, and separator can be manufactured using processes such as winding or stacking.

[0074] Normally, during the charging and discharging process of a secondary battery, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor of ions between the positive and negative electrodes. The separator, placed between the positive and negative electrodes, primarily prevents short circuits between the electrodes while allowing ions to pass through.

[0075] Please refer to Figure 1. Some embodiments of this application provide a battery cell 10. Figure 1 is an exploded perspective view of the battery cell 10 in some embodiments of this application. Figure 2 shows the overcharge protection mechanism 13 of the battery cell 10.

[0076] The battery cell 10 includes a casing 11, an electrode assembly 12, and an overcharge protection mechanism 13 (see Figure 2). The casing 11 has a first surface 111, and the electrode assembly 12 and electrolyte (not shown) are encapsulated within the casing 11. The overcharge protection mechanism 13 is disposed on the first surface 111. The electrolyte includes a gas-generating agent; the gas-generating agent has a response voltage, and when the overcharge voltage reaches the response voltage, the gas-generating agent undergoes a polymerization reaction and generates gas, triggering the overcharge protection mechanism 13.

[0077] In some embodiments, the housing 11 includes a housing 110 and an end cap. The housing 110 has an internal cavity for accommodating the electrode assembly 12. The housing 110 has an opening communicating with the cavity. The end cap closes to the opening of the housing 110 to form a sealed connection, thereby creating a sealed space for accommodating the electrode assembly 12 and the electrolyte. The end cap can be connected to the housing 110 by welding, bonding, snap-fitting, or other connection methods.

[0078] In some embodiments, the material of the outer casing 11 can be metal or a combination of metal and non-metal. For example, the outer casing 11 can be made of metal, such as aluminum, copper, iron, aluminum, steel or aluminum alloy. Alternatively, some parts of the outer casing 11 can be made of metal, while the rest can be made of non-metal. For example, the end cap of the outer casing 11 can be made of metal, while the shell 110 or other parts of the outer casing 11 can be made of non-metallic materials.

[0079] In some embodiments, when assembling the battery cell 10, the electrode assembly 12 can be placed into the housing 110 first, and electrolyte can be filled into the housing 110. Then, the end cap can be closed onto the opening of the housing 110 to complete the assembly of the battery cell 10. Alternatively, in some embodiments, when assembling the battery cell 10, the electrode assembly 12 can be placed into the housing 110 first, and then the end cap can be closed onto the opening of the housing 110. Electrolyte can then be filled into the housing 110 through the injection hole on the end cap, and then the injection hole can be closed to complete the assembly of the battery cell 10.

[0080] The outer shell 11 can be of various shapes, such as a cylinder or a prism. The shape of the outer shell 11 can be determined according to the specific shape of the electrode assembly 12. For example, if the electrode assembly 12 is a cylindrical structure, then a cylindrical outer shell 11 can be selected. If the electrode assembly 12 is a flat structure, then the outer shell 11 can be square.

[0081] In some embodiments, referring to FIG2, the overcharge protection mechanism 13 is a component disposed on the first surface 111. The overcharge protection mechanism 13 can be used to realize overcharge protection of the battery cell 10. For example, when the battery cell 10 is in an abuse condition such as overcharging, the overcharge protection mechanism 13 can be triggered by the internal pressure of the battery cell 10, thereby performing a corresponding action to achieve the purpose of cutting off the charging and discharging circuit of the battery cell 10. For example, referring to Figures 1-3, the overcharge protection mechanism 13 may include a short-circuit component (SSD). The short-circuit component may include a first deformable member 130 (e.g., a flip-over piece). The first deformable member 130 is electrically connected to the first surface 111. When the battery cell 10 is under abuse conditions such as overcharging, the internal pressure increases. When the internal pressure reaches a certain level, the deformable member deforms to contact the outside, thereby connecting the first surface 111 and the first electrode terminal 14. This causes a short circuit between the positive and negative electrodes inside the battery cell 10, resulting in an internal short circuit. The instantaneously generated large current can melt the electrical connection components inside the battery cell 10, cutting off the charging and discharging circuit of the battery cell 10, thereby providing overcharge protection. The melted electrical connection components may include a first adapter 121 and / or a second adapter 123. For example, the first adapter 121 has a first fusible portion. The thickness or width of the first fusible portion may be smaller than the thickness or width of the rest of the first adapter 121, so that when a large current passes through, the first fusible portion can melt and break the current path between the first tab 120 and the first electrode terminal 14.

[0082] For example, the overcharge protection mechanism 13 may include a circuit breaker (CID), which may include a deformable element and a current-cutting structure. The first electrode terminal 14 can be connected to the first adapter 121 through the circuit breaker. When the battery cell 10 is under abuse conditions such as overcharging, the internal pressure increases. When the internal pressure reaches a certain level, the deformable element deforms to break the current-cutting structure, thereby disconnecting the circuit between the first electrode terminal 14 and the first adapter 121, thus cutting off the charging and discharging circuit of the battery cell 10 and providing overcharge protection.

[0083] In some embodiments of this application, the response voltage is greater than the upper limit of the operating voltage of the battery cell.

[0084] In the above technical solution, by setting the response voltage to be greater than the upper limit of the working voltage of the battery cell, the gas-generating agent can undergo a polymerization reaction and generate gas when the overcharge voltage reaches the response voltage, thereby triggering the overcharge protection mechanism.

[0085] For example, if the upper limit of the operating voltage of a lithium iron phosphate secondary battery is 3.7V, then the response voltage of the gas-generating agent is greater than 3.7V.

[0086] In some embodiments of this application, the response voltage is 4.5V to 5.475V.

[0087] In the above technical solution, by setting the corresponding voltage to 4.5V to 5.475V, a polymerization reaction can be quickly and timely generated when the battery cell is overcharged, thus triggering the overcharge protection mechanism.

[0088] For example, in some embodiments of this application, the response voltage is 4.5V, 4.55V, 4.6V, 4.65V, 4.7V, 4.75V, 4.8V, 4.85V, 4.9V, 5.0V, 5.1V, 5.2V, 5.3V, 5.4V, 5.45V, 5.475V, or a range between any two of the aforementioned values.

[0089] In some embodiments of this application, the aforementioned response voltage refers to the voltage at which the gas-generating agent begins to undergo an oxidative electropolymerization reaction.

[0090] For example, biphenyl can undergo oxidative electropolymerization at 4.5V to 4.75V to produce a large amount of gas, where 4.5V is the response voltage of biphenyl.

[0091] In some embodiments of this application, the gas-generating agent is capable of undergoing a polymerization reaction and generating gas when the response voltage is reached.

[0092] In some embodiments of this application, the gas-generating agent includes one or more aromatic compounds having the structure shown below;

[0093] Wherein, X includes at least one of phenyl, cyclohexyl, methyl, straight-chain alkane group or branched-chain alkane group having 1 to 6 carbon atoms.

[0094] In the above technical solution, the aromatic hydrocarbon or aromatic hydrocarbon compound having the structure shown above can undergo a polymerization reaction and generate gas when the overcharge voltage reaches the response voltage, and trigger the overcharge protection mechanism.

[0095] In some embodiments of this application, the gas-generating agent includes at least one of biphenyl, cyclohexylbenzene, or tert-butylbenzene.

[0096] In the above technical solution, the gas-generating agent includes at least one of biphenyl, cyclohexylbenzene, or tert-butylbenzene; it is capable of undergoing a polymerization reaction and generating gas when the overcharge voltage reaches the response voltage, and triggering the overcharge protection mechanism.

[0097] For example, in some embodiments of this application, the gas-generating agent is any one of biphenyl, cyclohexylbenzene, or tert-butylbenzene; or in some embodiments of this application, the gas-generating agent is a mixture of biphenyl and cyclohexylbenzene; or the gas-generating agent is a mixture of biphenyl and tert-butylbenzene; or the gas-generating agent is a mixture of biphenyl, cyclohexylbenzene, and tert-butylbenzene; or the gas-generating agent is a mixture of cyclohexylbenzene and tert-butylbenzene. The raw materials in each of the above mixtures can be mixed in any proportion.

[0098] In some embodiments of this application, the gas-generating agent accounts for 0.5% to 10% of the mass of the electrolyte.

[0099] In the above technical solution, by setting the mass ratio of the gas-generating agent in the electrolyte to 0.5% to 10%, gas can be effectively generated. When the overcharge voltage reaches the response voltage, a polymerization reaction occurs and gas is generated, triggering the overcharge protection mechanism. This can also effectively shorten the time for triggering the overcharge protection mechanism.

[0100] For example, in some embodiments of this application, the mass percentage of the gas-generating agent in the electrolyte is 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two of the aforementioned values.

[0101] In some embodiments of this application, the gas-generating agent accounts for 1% to 5% of the mass of the electrolyte.

[0102] In the above technical solution, by further limiting the mass ratio of the gas-generating agent in the electrolyte to 1% to 5%, gas can be effectively generated. When the overcharge voltage reaches the response voltage, a polymerization reaction occurs and gas is generated, triggering the overcharge protection mechanism. Furthermore, the time for triggering the overcharge protection mechanism can be further effectively shortened.

[0103] For example, in some embodiments of this application, the mass percentage of the gas-generating agent in the electrolyte is 1%, 1.2%, 1.5%, 1.8%, 2.5%, 3.5%, 4.5%, 4.8%, or any two of the aforementioned values.

[0104] In some embodiments of this application, please refer to Figures 2-5. Figure 2 is a schematic diagram of the internal structure of a partial structure of a battery cell 10 in some embodiments of this application; Figure 3 is an exploded perspective view of a partial structure of a battery cell 10 in some embodiments of this application; Figure 4 is a schematic diagram of the first surface 111, the first electrode terminal 14, and the first deformable member 130 in some embodiments of this application; and Figure 5 is a schematic diagram of the first deformable member 130 in some embodiments of this application.

[0105] The battery cell 10 also includes a first electrode terminal 14, which is insulated from the first surface 111. The overcharge protection mechanism 13 includes a first deformable member 130, which is electrically connected to the first surface 111 and is configured to deform under air pressure to contact the first electrode terminal 14.

[0106] In some embodiments, the first electrode terminal 14 is a component mounted on the first surface 111, and the first electrode terminal 14 is insulated from the first surface 111. For example, an insulating structure is provided between the first electrode terminal 14 and the first surface 111. The first electrode terminal 14 is used to be electrically connected to the electrode assembly 12, so that current flows into or out of the first tab 120 through the first electrode terminal 14.

[0107] The overcharge protection mechanism 13 can be a short-circuit component. In some embodiments, the overcharge protection mechanism 13 includes a first deformable member 130. The first deformable member 130 is mounted on the first surface 111 and is electrically connected to the first surface 111. In some embodiments, the first deformable member 130 can be made of a metallic material, such as aluminum, copper, iron, steel, alloy, or composite metal. In some embodiments, the first deformable member 130 can be welded to the inner surface of the first surface 111.

[0108] The first deformable member 130 is a structural member that deforms under the internal pressure of the battery cell 10. The first deformable member 130 is used for overcharge protection of the battery cell 10. For example, the gas-generating agent decomposes and generates gas when the voltage exceeds a threshold, which causes the internal pressure of the battery cell 10 to increase. When the internal pressure reaches a certain level, such as the first threshold, the first deformable member 130 deforms to contact the first electrode terminal 14, thereby conducting the first surface 111 and the first electrode terminal 14 and short-circuiting the positive and negative electrodes inside the battery cell 10.

[0109] For example, the battery cell 10 is provided with a single short-circuit component, the first electrode terminal 14 is electrically connected to the first tab 120 through the first adapter 121, the second tab 122 of the electrode assembly 12 can be electrically connected to the first surface 111, the second tab 122 is opposite in polarity to the first tab 120, the second tab 122 is directly connected to the first surface 111 or through the second adapter 123, or the first surface 111 is provided with a second electrode terminal 16, the second electrode terminal 16 is electrically connected to the first surface 111, and the second tab 122 is directly connected to the second electrode terminal 16 or through the second adapter 123. The gas-generating agent decomposes and generates gas when the voltage exceeds a threshold, causing an increase in the internal pressure of the battery cell 10. When the internal pressure reaches a certain level, such as the first threshold, the first deformable member 130 deforms, short-circuiting the first electrode terminal 14 and the first surface 111. This short-circuit creates an internal short circuit between the positive and negative electrodes of the battery cell 10. The instantaneously generated large current can melt the electrical connection components inside the battery cell 10, cutting off the charging and discharging circuit of the battery cell 10, thereby providing overcharge protection. The melted electrical connection components may include the first adapter 121 and / or the second adapter 123. For example, the first adapter 121 has a first fusible portion. The thickness or width of the first fusible portion may be smaller than the thickness or width of the rest of the first adapter 121, so that when a large current passes through, the first fusible portion can melt, thereby disconnecting the current path between the first tab 120 and the first electrode terminal 14.

[0110] For example, the battery cell 10 is provided with two short-circuit components, corresponding to the positive and negative terminals respectively, including a first deformable member 130 and a second deformable member 131. A first electrode terminal 14 is insulatedly mounted on a first surface 111 and electrically connected to a first tab 120 via a first adapter 121. A second electrode terminal 16 is insulatedly mounted on the first surface 111 and connected to a second tab 122 via a second adapter 123. The second electrode terminal 16 is correspondingly provided with a second deformable member 131, which is electrically connected to the first surface 111. The second deformable member 131 is used to deform and contact the second electrode terminal 16 when the internal pressure of the battery cell 10 reaches a certain level, such as a second threshold, so as to electrically connect the second electrode terminal 16 to the first surface 111.

[0111] The gas-generating agent decomposes and generates gas when the voltage exceeds a threshold, causing an increase in the internal pressure of the battery cell 10. When the internal pressure reaches a certain level, such as the first threshold, the first deformable member 130 deforms and contacts the first conductive member 140, short-circuiting the first electrode terminal 14 and the first surface 111. When the internal pressure of the battery cell 10 reaches the second threshold, the second deformable member 131 deforms and short-circuits the second electrode terminal 16 and the first surface 111, thereby short-circuiting the positive and negative electrodes inside the battery cell 10 to form an internal short circuit. The instantaneously generated large current can melt the electrical connection components inside the battery cell 10, cutting off the charging and discharging circuit of the battery cell 10, thus providing overcharge protection. The melted electrical connection components may include the first adapter 121 and / or the second adapter 123. For example, the first adapter 121 has a first fusible part, which can melt when a large current passes through, thereby disconnecting the current path between the first tab 120 and the first electrode terminal 14.

[0112] In the above scheme, by setting the first deformable member 130, when the internal pressure of the battery cell 10 reaches a certain level, such as the first threshold, the deformation of the first deformable member 130 to contact the first electrode terminal 14 causes the positive and negative terminals of the battery cell 10 to be short-circuited internally. This causes the electrical connection components inside the battery cell 10 to melt due to the large current generated by the short circuit, thereby cutting off the charging and discharging circuit of the battery cell 10. This provides overcharge protection and reduces the risk of thermal runaway of the battery cell 10, thus making the battery more reliable.

[0113] According to some embodiments of this application, please refer to FIG4. The first electrode terminal 14 includes a first conductive element 140 and a first electrode post 141, which are interconnected. The first conductive element 140 is disposed on the outside of the first surface 111 and is insulated from the first surface 111. The first electrode post 141 is electrically connected to the electrode assembly 12. The first deformable element 130 is configured to deform under air pressure to contact the first conductive element 140, so as to electrically connect the first electrode post 141 to the first surface 111.

[0114] In some embodiments, the first electrode terminal 14 includes a first conductive element 140 and a first terminal post 141. The first conductive element 140 is located on the side of the first surface 111 opposite to the electrode assembly 12, and is used to connect to an external busbar (e.g., a power strip). Exemplarily, the first conductive element 140 is welded to the busbar. The first terminal post 141 is connected to the first tab 120 of the electrode assembly 12. Exemplarily, the first terminal post 141 is connected to the first tab 120 via a first adapter 121. The first conductive element 140 and the first terminal post 141 are interconnected, and the connection between the first conductive element 140 and the first terminal post 141 includes welding, riveting, threaded connection, or integral molding, etc. For example, in some embodiments, the first conductive element 140 and the first pole post 141 are riveted to each other. The first conductive element 140 is generally plate-shaped and has a riveting hole. The first pole post 141 is generally columnar, such as cylindrical or polygonal columnar. Part of the first pole post 141 passes through the first through hole 1111 of the first surface 111 and is riveted to the riveting hole. The other part is located inside the housing 11 and is connected to the first tab 120 through the first adapter 121.

[0115] In some embodiments, an insulating structure is provided between the first conductive element 140 and the first surface 111. Exemplarily, the first conductive element 140 and the first surface 111 are insulated from each other by a first insulating element 150.

[0116] In some embodiments, a first through hole 1111 is formed on the first surface 111, and a first deformable member 130 closes the first through hole 1111. When the internal pressure of the battery cell 10 is at a certain level, the first deformable member 130 can deform to pass through the first through hole 1111 and contact the first conductive member 140.

[0117] In the above scheme, by setting the first conductive element 140 on the outside of the first surface 111, it is convenient to connect with the external busbar component. On the other hand, it is beneficial for the first deformable element 130 to deform outward under the action of internal pressure to effectively conduct the first electrode terminal 14 and the first surface 111, thereby achieving overcharge protection and improving battery reliability.

[0118] According to some embodiments of this application, the battery cell 10 further includes a first insulating member 150, at least a portion of which is disposed between the first conductive member 140 and the first surface 111.

[0119] In some embodiments, a first insulating member 150 is disposed between the first conductive member 140 and the first surface 111, the first insulating member 150 serving to insulate and isolate the first conductive member 140 and the first surface 111. In some embodiments, the first insulating member 150 can be made of a material with a high resistance value, such as organic insulating materials, inorganic insulating materials, or mixed insulating materials. Exemplarily, in some embodiments of this application, the material of the first insulating member 150 may include insulating PPS (polyphenylene sulfide) material. In other embodiments, the first insulating member 150 may also be made of other materials with insulating properties such as polypropylene and polyethylene.

[0120] In some embodiments, a portion of the first insulating member 150 may be located between the first surface 111 and the first conductive member 140, and another portion of the first insulating member 150 may surround the outer peripheral surface of the first conductive member 140.

[0121] In some embodiments, a first electrode lead-out hole 1110 is formed on the first surface 111, a first electrode post 141 passes through the first electrode lead-out hole 1110, a portion of the first insulating member 150 may be located between the first surface 111 and the first conductive member 140, a portion of the first insulating member 150 may surround the outer peripheral surface of the first conductive member 140, and another portion of the first insulating member 150 may be located in the first electrode lead-out hole 1110 and between the first electrode post 141 and the hole wall of the first electrode lead-out hole 1110.

[0122] In the above solution, by providing a first insulating member 150 between the first surface 111 and the first conductive member 140, the first surface 111 and the first conductive member 140 can be effectively insulated and isolated, reducing the risk of internal short circuit in the battery cell 10 due to short circuit between the first surface 111 and the first conductive member 140, thus ensuring high battery reliability. Especially in energy storage devices with high operating voltage, by providing a first insulating member 150 between the first surface 111 and the first conductive member 140, the risk of thermal runaway of the energy storage device can be effectively reduced due to the high voltage of the casing 11 becoming high-voltage due to the runaway of other battery cells 10 in the battery, which could cause the high voltage to conduct through the first surface 111 and the first conductive member 140, resulting in an internal short circuit in the battery cell 10.

[0123] According to some embodiments of this application, the resistance value of the first insulating element 150 is greater than or equal to 200 megohms.

[0124] In some embodiments, a first insulating element 150 with a resistance value greater than or equal to 200 megohms may be provided between the first surface 111 and the first conductive element 140. That is, in some embodiments, the resistance value of the first insulating element 150 may be 200 megohms, 210 megohms, 220 megohms or greater.

[0125] In some embodiments, the resistance value of the first insulating component 150 can be measured using testing methods such as multimeter testing, bridge test, voltmeter-ammeter method, and ohmmeter method. In some embodiments, the resistance value of the first insulating component 150 can be measured using a megohmmeter.

[0126] In the above scheme, by setting the resistance value of the first insulating component 150 to be greater than or equal to 200 megohms, the high voltage resistance of the insulation between the first conductive component 140 and the first surface 111 can be effectively improved, which can effectively meet the insulation resistance requirements of the energy storage device, reduce the risk of external voltage breaking down the first insulating component 150 to conduct the first surface 111 and the first conductive component 140, causing an internal short circuit in the battery cell 10, and make the energy storage device have high reliability.

[0127] According to some embodiments of this application, please refer to Figures 3 and 4. The first surface 111 has a first electrode lead-out hole 1110, and a first electrode post 141 passes through the first electrode lead-out hole 1110. The battery cell 10 also includes a second insulating member 151, at least a portion of which is disposed between the hole wall of the first electrode lead-out hole 1110 and the first electrode post 141.

[0128] The first electrode lead-out hole 1110 is a through hole structure that penetrates the first surface 111. Part of the first electrode post 141 is located inside the first electrode lead-out hole 1110, part of the first electrode post 141 is located on the outside of the first surface 111 to be connected to the first conductive member 140, and the other part of the first electrode post 141 is located on the inside of the first surface 111 to be connected to the first adapter 121.

[0129] The second insulating member 151 is used to insulate and isolate the first electrode post 141 from the first surface 111. The phrase "at least a portion of the second insulating member 151 is disposed between the hole wall of the first electrode lead-out hole 1110 and the first electrode post 141" can be understood as follows: the second insulating member 151 is disposed between the hole wall of the first electrode lead-out hole 1110 and the outer peripheral surface of the first electrode post 141; or, a portion of the second insulating member 151 is disposed between the hole wall of the first electrode lead-out hole 1110 and the outer peripheral surface of the first electrode post 141, and another portion of the second insulating member 151 is disposed between the inner surface of the first surface 111 and the first electrode post 141.

[0130] In some embodiments, the second insulating element 151 can be made of a material with a high resistance value, such as an organic insulating material, an inorganic insulating material, or a mixed insulating material. Exemplarily, in some embodiments of this application, the material of the second insulating element 151 may include insulating PPS (polyphenylene sulfide) material. In other embodiments, the second insulating element 151 may also be made of other materials with insulating properties, such as polypropylene and polyethylene.

[0131] In the above scheme, by setting a second insulating member 151 between the hole wall of the first electrode lead-out hole 1110 and the first electrode post 141, the first surface 111 and the first electrode post 141 can be effectively insulated and isolated, reducing the risk of internal short circuit of the battery cell 10 caused by short circuit between the first surface 111 and the first electrode post 141, thus making the battery highly reliable.

[0132] According to some embodiments of this application, a first flange 1410 is formed on the outer peripheral surface of the first pole post 141, and a portion of the second insulating member 151 is located between the first flange 1410 and the inner surface of the first surface 111 along the thickness direction z of the first surface.

[0133] The first flange 1410 is a component formed on the outer peripheral surface of the first pole post 141. In some embodiments, the first flange 1410 may be an annular structure around the circumference of the first pole post 141. In other embodiments, the first flange 1410 may also be a block structure. The number of first flanges 1410 may be one or more. When there are multiple first flanges 1410, the multiple first flanges 1410 may be spaced apart around the circumference of the first pole post 141. The circumference of the first pole post 141 may be a direction perpendicular to the axial direction of the first pole post 141.

[0134] The statement "A portion of the second insulating member 151 is located between the first flange 1410 and the inner surface of the first surface 111 along the thickness direction z of the first surface" can be understood as follows: along the thickness direction z of the first surface, a portion of the second insulating member 151 is located between the side of the first flange 1410 facing the first surface 111 and the inner surface of the first surface 111. In some embodiments, along the thickness direction z of the first surface, the projection of the second insulating member 151 can cover the first flange 1410. In some embodiments, along the thickness direction z of the first surface, the projection of the first flange 1410 can cover the projection of the second insulating member 151.

[0135] In the above solution, by partially disposing the second insulating member 151 between the inner surface of the first flange 1410 and the first surface 111, it can effectively insulate and isolate the first pole post 141 and the first surface 111, and restrict the movement of the first pole post 141 in the thickness direction z of the first surface, so that the first electrode terminal 14 is stably disposed on the first surface 111.

[0136] According to some embodiments of this application, the resistance value of the second insulating element 151 is greater than or equal to 200 megohms.

[0137] In some embodiments, a second insulating element 151 with a resistance value greater than or equal to 200 megohms may be provided between the first surface 111 and the first terminal 141. That is, in some embodiments, the resistance value of the second insulating element 151 may be 200 megohms, 210 megohms, 220 megohms or greater.

[0138] In some embodiments, the resistance value of the second insulating component 151 can be measured using testing methods such as multimeter testing, bridge test, voltmeter-ammeter method, and ohmmeter method. In some embodiments, the resistance value of the second insulating component 151 can be measured using a megohmmeter.

[0139] In the above scheme, by setting the resistance value of the second insulating component 151 to be greater than or equal to 200 megohms, the high voltage resistance of the insulation between the first terminal 141 and the first surface 111 can be effectively improved, which can effectively meet the insulation resistance requirements of the energy storage device, reduce the risk of external voltage breaking down the second insulating component 151 to conduct the first surface 111 and the first terminal 141, causing an internal short circuit in the battery cell 10, and make the energy storage device have high reliability.

[0140] According to some embodiments of this application, please refer to FIG4. A first protrusion 1400 is provided on the surface of the first conductive member 140 facing the first surface 111. The first protrusion 1400 is used to contact the first deformable member 130.

[0141] Along the direction from the outer side to the inner side of the first surface 111, the first protrusion 1400 protrudes from the surface of the first conductive member 140 facing the first surface 111. In some embodiments, the surface of the first conductive member 140 facing the first surface 111 is the inner surface of the first conductive member 140, and along the direction from the outer side to the inner side of the first surface 111, the first protrusion 1400 may extend beyond the side where the first insulating member 150 contacts the inner surface of the first conductive member 140.

[0142] The first protrusion 1400 is used to contact the first deformable member 130. For example, when the internal pressure of the battery cell 10 is at a first level, the first deformable member 130 deforms in the direction from the inside of the first surface 111 to the outside of the first surface 111 and contacts the first protrusion 1400, thereby making the first surface 111 connected to the first electrode terminal 14.

[0143] In the above solution, by providing a first protrusion 1400 on the side of the first conductive member 140 facing the first surface 111, the travel distance between the first deformable member 130 and the first conductive member 140 after deformation can be shortened, effectively improving the sensitivity and timeliness of overcharge protection and contributing to the improvement of battery reliability.

[0144] According to some embodiments of this application, please refer to FIG5. The first deformable member 130 includes a first contact portion 1300, a first deformable portion 1301, and a first connecting portion 1302. The first deformable portion 1301 is disposed on the outer peripheral surface of the first contact portion 1300, and the first connecting portion 1302 is disposed on the end of the first deformable portion 1301 opposite to the first contact portion 1300. The first connecting portion 1302 is connected to the first surface 111. The first deformable portion 1301 is configured to be deformable so that the first contact portion 1300 contacts the first conductive member 140.

[0145] In some embodiments, the first deformable member 130 may be a first flip piece, the edge of which is welded to the first surface 111. The first flip piece is flipped under pressure and thus comes into contact with the first conductive member 140.

[0146] In some embodiments, referring to FIG5, the first deformable member 130 may include, from the inside out, a first contact portion 1300, a first deformable portion 1301, and a first connecting portion 1302. The first contact portion 1300 may be columnar and is used to contact the first conductive member 140. The first deformable member 130 is connected to the outer peripheral surface of the first contact portion 1300. The first deformable portion 1301 may be foil-shaped and extend circumferentially around the first contact portion 1300. The first connecting portion 1302 may be annular and is disposed at one end of the first deformable portion 1301 opposite to the first contact portion 1300. The first connecting portion 1302 is connected to the first surface 111, for example, by welding to the first surface 111.

[0147] In some embodiments of this application, the thickness of the first deformed portion 1301 is 0.1 mm to 0.5 mm.

[0148] For example, in some embodiments of this application, the thickness of the first deformed portion 1301 is 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or any two of the aforementioned values.

[0149] In the above technical solution, by setting the thickness of the first deformable part 1301 to 0.1mm to 0.5mm, the first deformable part 1301 can be effectively deformed under the action of the gas generating agent to contact the first electrode terminal 14, thereby realizing the triggering of the overcharge protection mechanism.

[0150] Further, optionally, in some embodiments of this application, the deformed portion can be circular with a diameter of 15mm to 25mm and a projected area of ​​225mm². 2 ~625mm 2The component of the deformed part can be aluminum; the overturning pressure can reach 0.6 MPa or above; it can effectively make the first deformed part 1301 deform under the action of the gas generating agent to contact the first electrode terminal 14; thereby realizing the triggering of the overcharge protection mechanism.

[0151] For example, the diameter of the deformed part can be 15mm, 16mm, 17mm, 18mm, 19mm, 20mm, 21mm, 22mm, 23mm, 24mm, 25mm or any two of the aforementioned values.

[0152] For example, the projected area of ​​the deformed part is 225 mm². 2 250mm 2 300mm 2 350mm 2 400mm 2 450mm 2 500mm 2 550mm 2 600mm 2 625mm 2 Or the range between any two of the aforementioned values.

[0153] For example, the overturning pressure of the deformed part can reach 0.6MPa, 0.65MPa, 0.7MPa, 0.75MPa, 0.8MPa, 0.85MPa or any two of the aforementioned values.

[0154] In some embodiments of this application, the above-described method for testing the overturning pressure of the deformed portion is as follows:

[0155] The resistance between the positive and negative terminals is monitored while air is injected through the liquid injection hole in the end cap, and the internal air pressure is monitored simultaneously. When the resistance between the positive and negative terminals is observed to be less than 1 ohm, the corresponding internal air pressure of the battery is the overturning pressure of the deformed part.

[0156] For example, when the overcharge protection mechanism 13 includes a short-circuit component (SSD), the first deformable portion 1301 is a flip-over piece. When the area of ​​the first deformable portion 1301 is within the aforementioned range and the pressure generated by the gas-generating agent is within the aforementioned range, the first deformable portion 1301 can be effectively flipped to contact the first electrode terminal 14, thereby connecting the first surface 111 and the first electrode terminal 14. This causes a short circuit between the positive and negative electrodes inside the battery cell 10, resulting in an internal short circuit in the battery cell 10. The instantaneously generated large current can melt the electrical connection components inside the battery cell 10, cutting off the charging and discharging circuit of the battery cell 10, thereby providing overcharge protection.

[0157] For example, when the overcharge protection mechanism 13 includes a circuit breaker (CID), and the area of ​​the first deformable portion 1301 is within the above-mentioned range, and the pressure generated by the gas-generating agent is within the above-mentioned range, the first deformable portion 1301 can be effectively deformed to break the current cutting structure, thereby disconnecting the circuit between the first electrode terminal 14 and the first adapter 121, thereby cutting off the charging and discharging circuit of the battery cell 10 and playing the role of overcharge protection.

[0158] In some embodiments, along the thickness direction z of the first surface, the projection of the first protrusion 1400 may cover the projection of the first contact portion 1300. In some embodiments, along the thickness direction z of the first surface, the projection of the first protrusion 1400 and the projection of the first contact portion 1300 coincide. In some embodiments, along the thickness direction z of the first surface, the projection of the first contact portion 1300 may cover the projection of the first protrusion 1400.

[0159] In the above scheme, the first deformable part 130 has a simple structure and is easy to manufacture. By deforming under force, the first contact part 1300 is activated and contacts the first conductive part 140, which can effectively play the role of overcharge protection and make the battery highly reliable.

[0160] According to some embodiments of this application, the maximum thickness of the first deformable portion 1301 is less than the maximum thickness of the first connecting portion 1302, and the maximum thickness of the first deformable portion 1301 is less than the maximum thickness of the first contact portion 1300.

[0161] In some embodiments, the maximum thickness of the first deformable portion 1301 may be less than the maximum thickness of the first connecting portion 1302, or it may be less than the maximum thickness of the first contact portion 1300.

[0162] For example, the cross-section of the first connecting portion 1302 may be square, and the thickness of the first connecting portion 1302 may be the dimension of the cross-section of the first connecting portion 1302 in the thickness direction z of the first surface. The thickness of the first contact portion 1300 may be the dimension of the first contact portion 1300 in the thickness direction z of the first surface.

[0163] In the above solution, by setting the thickness of the first deformable part 1301 to be relatively small, when the internal pressure of the battery cell 10 is at a certain level, the first contact part 1300 can contact the first conductive element 140 due to the deformation of the first deformable part 1301, thereby realizing overcharge protection in a timely and effective manner and improving the reliability of the battery.

[0164] According to some embodiments of this application, please refer to Figures 3 and 6. Figure 6 is a schematic diagram of the first surface 111, the second electrode terminal 16, and the second deformed member 131 in some embodiments of this application.

[0165] The battery cell 10 also includes a second electrode terminal 16 and a second deformable member 131. The second electrode terminal 16 is insulated from the first surface 111. The second deformable member 131 is electrically connected to the first surface 111 and is configured to deform to contact the second electrode terminal 16.

[0166] In some embodiments, the battery cell 10 further includes a second electrode terminal 16, which is electrically connected to the second tab 122 of the electrode assembly 12 for connection to an external busbar. The polarity of the second electrode terminal 16 is opposite to that of the first electrode terminal 14; for example, the first electrode terminal 14 is a positive electrode terminal, and the second electrode terminal 16 is a negative electrode terminal. The second electrode terminal 16 is used for electrical connection with the electrode assembly 12, allowing current to flow into or out of the second tab 122. In some embodiments, the second electrode terminal 16 is made of a metallic material, such as aluminum, copper, iron, steel, alloys, or composite metals. In some embodiments, the second electrode terminal 16 can be connected to the second tab 122 via a second adapter 123.

[0167] In some embodiments, the second electrode terminal 16 includes a second conductive element 160 and a second electrode post 161. The second conductive element 160 is located on the outer side of the first surface 111 and is used to connect to an external busbar (e.g., a power strip). In some embodiments, the first surface 111 has a second electrode lead-out hole 1112, and the second electrode post 161 passes through the second electrode lead-out hole 1112 and is connected to the second electrode tab 122 via a second adapter 123. The second conductive element 160 and the second electrode post 161 are interconnected. The connection between the second conductive element 160 and the second electrode post 161 includes welding, riveting, threaded connection, or integral molding, etc. For example, in some embodiments, the second conductive element 160 and the second pole post 161 are riveted to each other. The second conductive element 160 is generally plate-shaped and has a riveting hole. The second pole post 161 is generally columnar, such as cylindrical or polygonal columnar. Part of the second pole post 161 passes through the second electrode lead-out hole 1112 of the first surface 111 and is riveted in the riveting hole. The other part is located inside the housing 11 and is connected to the second electrode tab 122 through the second adapter 123.

[0168] In some embodiments, a third insulating member 152 is provided between the second conductive member 160 and the first surface 111, and the third insulating member 152 is used to insulate and isolate the second conductive member 160 from the first surface 111. A fourth insulating member 153 is provided between the second electrode post 161 and the first surface 111, for example, the fourth insulating member 153 is provided between the outer periphery of the second electrode post 161 and the wall of the third through hole.

[0169] In some embodiments, the third insulating element 152 and / or the fourth insulating element 153 may be made of materials with higher resistivity, such as organic insulating materials, inorganic insulating materials, or mixed insulating materials. Exemplarily, in some embodiments of this application, the materials of the third insulating element 152 and / or the fourth insulating element 153 may include insulating PPS (polyphenylene sulfide) material. In other embodiments, the third insulating element 152 and / or the fourth insulating element 153 may also be made of other materials with insulating properties, such as polypropylene and polyethylene.

[0170] In some embodiments, the resistance values ​​of the third insulating member 152 and / or the fourth insulating member 153 can be expressed in megaohms (MΩ). For example, in some embodiments of the battery cell 10 provided in this application, the resistance values ​​of the third insulating member 152 and / or the fourth insulating member 153 can be greater than or equal to 200 MΩ.

[0171] In some embodiments, the second deformable member 131 is a short-circuit component. The second deformable member 131 is mounted on the first surface 111 and is electrically connected to the first surface 111. In some embodiments, the second deformable member 131 can be made of a metallic material, such as aluminum, copper, iron, steel, alloy, or composite metal. In some embodiments, the second deformable member 131 can be welded to the inner surface of the first surface 111. In some embodiments, the first surface 111 has a second through hole 1113, and the second deformable member 131 closes the second through hole 1113.

[0172] The second deformable member 131 is a structural member that deforms under the internal pressure of the battery cell 10. The second deformable member 131 is used for overcharge protection of the battery cell 10. For example, when the battery cell 10 is in an abuse condition such as overcharging, the internal pressure increases. When the internal pressure reaches a certain level, such as a second threshold, the second deformable member 131 deforms to pass through the second through hole 1113 and contact the second conductive member 160, thereby making the second electrode terminal 16 and the first electrode terminal 14 electrically connected to each other through the first surface 111, so that the positive and negative electrodes inside the battery cell 10 are short-circuited.

[0173] In some embodiments, the second deformable member 131 may be a flip-over piece that flips under pressure. Similar to the first deformable member 130 described above, the second deformable member 131 may include a second contact portion, a second deformable portion, and a second connecting portion. The second deformable portion is disposed on the outer peripheral surface of the second contact portion, and the second connecting portion is disposed at the end of the second deformable portion opposite to the second contact portion. The second connecting portion is connected to the first surface 111, and the first deformable portion 1301 is configured to deform so that the second contact portion contacts the second conductive member 160.

[0174] In some embodiments, the surface of the second conductive member 160 facing the first surface 111 is provided with a second protrusion 1600, which is used to contact the second deformable member 131. In some embodiments, along the thickness direction z of the first surface, the projection of the second protrusion 1600 may cover the projection of the second contact portion. In some embodiments, along the thickness direction z of the first surface, the projection of the second protrusion 1600 and the projection of the second contact portion coincide. In some embodiments, along the thickness direction z of the first surface, the projection of the second contact portion may cover the projection of the second protrusion 1600.

[0175] In some embodiments, the first deformable member 130 deforms and releases the first conductive member 140 when the internal pressure of the battery cell 10 reaches a first threshold, and the second deformable member 131 deforms and contacts the second conductive member 160 when the internal pressure of the battery cell 10 reaches a second threshold. In some embodiments, the first threshold and the second threshold may be equal or unequal.

[0176] For example, when the battery cell 10 is in an abused condition due to overcharging, the gas-generating agent is decomposed, and the internal pressure of the battery cell 10 increases. When the internal pressure of the battery cell 10 reaches a first threshold, the first deformable member 130 deforms, short-circuiting the first electrode terminal 14 and the first surface 111. When the internal pressure of the battery cell 10 reaches a second threshold, the second deformable member 131 deforms, short-circuiting the second electrode terminal 16 and the first surface 111, thereby short-circuiting the positive and negative electrodes inside the battery cell 10 to form an internal short circuit. The instantaneously generated large current can melt the electrical connection components inside the battery cell 10, cutting off the charging and discharging circuit of the battery cell 10, thereby playing the role of overcharge protection. The melted electrical connection components may include the first adapter 121 and / or the second adapter 123. For example, the first adapter 121 has a first fusible part, which can melt when a large current passes through, thereby disconnecting the current path between the first tab 120 and the first electrode terminal 14.

[0177] In the above scheme, by setting the second deformable member 131, when the internal pressure of the battery cell 10 reaches a certain level, such as the second threshold, the second deformable member 131 deforms to contact the second electrode terminal 16, thereby making the second electrode terminal 16 electrically connected to the second wall. Combined with the short circuit between the first deformable member 130 and the first electrode terminal 14, the electrical connection component inside the battery cell 10 melts due to the large current generated by the short circuit, thereby cutting off the charging and discharging circuit of the battery cell 10, thus playing the role of overcharge protection and reducing the risk of thermal runaway of the battery cell 10, thereby making the battery have high reliability. On the other hand, since the first electrode terminal 14 and the second electrode terminal 16 are both insulated from the first surface 111 under non-abuse conditions, the outer shell 11 of the battery cell 10 can be de-energized, which is beneficial for the battery cell 10 to form an energy storage device, and reduces the risk of arcing and breakdown between two adjacent battery cells 10 in the energy storage device.

[0178] According to some embodiments of this application, the second electrode terminal 16 is a negative electrode terminal, such that the minimum pressure value for the deformation of the second deformable member 131 is greater than the minimum pressure value for the deformation of the first deformable member 130.

[0179] In some embodiments, the second electrode terminal 16 is a negative electrode terminal, meaning that the second electrode terminal 16 is electrically connected to the negative electrode tab of the electrode assembly 12. When the internal pressure of the battery cell 10 reaches a first threshold, the first deformable member 130 deforms and contacts the first conductive member 140. When the internal pressure of the battery cell 10 reaches a second threshold and contacts the second conductive member 160, the second deformable member 131 deforms, and the second threshold may be greater than the first threshold.

[0180] "The second threshold is greater than the first threshold" can be understood as the second deformable part 131 being less prone to deformation than the first deformable part 130. That is, the second deformable part 131 will only deform when the internal pressure of the battery cell 10 further increases and exceeds the first threshold.

[0181] In some embodiments, the manufacturing material or structure of the second deformable member 131 can be changed to make the second deformable member 131 less prone to deformation than the first deformable member 130. For example, in some embodiments, the thickness of the second deformed portion of the second deformable member 131 is greater than the thickness of the first deformed portion 1301 of the first deformable member 130, so that the second deformable member 131 deforms only to contact the second electrode terminal 16 under greater pressure. Alternatively, in some embodiments, a reinforcing structure, such as a reinforcing rib or reinforcing protrusion, is provided on the second deformed portion, so that the second deformable member 131 deforms only to contact the second electrode terminal 16 under greater pressure.

[0182] In some embodiments, "the second threshold is greater than the first threshold" can be understood as the second deformable member 131 requiring greater pressure than the first deformable member 130 to contact the second electrode terminal 16. That is, the second deformable member 131 only contacts the second electrode terminal 16 when the internal pressure of the battery cell 10 further increases and exceeds the first threshold. For example, the distance between the second deformable member 131 and the second electrode terminal 16 can be increased so that the second deformable member 131 requires a greater amount of deformation to contact the second electrode terminal 16. For instance, along the thickness direction z of the first surface, the distance between the second contact portion and the second electrode terminal 16 is greater than the distance between the first contact portion 1300 and the first electrode terminal 14.

[0183] In the above scheme, when the second electrode terminal 16 is the negative electrode terminal, by making the minimum pressure value that causes the second deformable member 131 to deform greater than the minimum pressure value that causes the first deformable member 130 to deform, the second deformable member 131 can deform when the internal pressure of the battery cell 10 is greater than that of the first deformable member 130. On the one hand, this enables the battery cell 10 to have overcharge protection function. On the other hand, it can reduce the risk that gas generation inside the battery cell 10 under non-overcharge abuse conditions will cause the second deformable member 131 to flip over, resulting in the casing 11 becoming negatively charged and being corroded by the electrolyte. This ensures the integrity of the casing 11 to a certain extent, reduces the risk of electrolyte leakage, and thus improves the reliability of the battery.

[0184] [Positive electrode plate]

[0185] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.

[0186] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0187] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. 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 substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0188] In some embodiments, when the secondary battery is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, 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 transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (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) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, 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 manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0189] In some embodiments, to further improve the energy density of secondary batteries, the positive electrode active material for lithium-ion batteries may include materials with the general formula Li. a Ni b Co c M d O e A fOne or more of lithium transition metal oxides and their modified compounds; wherein, 0.8 ≤ a ≤ 1.2, 0.5 ≤ b < 1, 0 < c < 1, 0 < d < 1, 1 ≤ e ≤ 2, 0 ≤ f ≤ 1, M is selected from one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is selected from one or more of N, F, S, and Cl.

[0190] In some embodiments, by way of example, the positive electrode active material for a lithium-ion battery may include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM 523 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM 811 )、LiNi 0.85 Co 0.15 Al 0.05 O2, LiFePO4, and LiMnPO4, or one or more of them.

[0191] In this application, the modified compounds of the above positive electrode active materials may be doping modification and / or surface coating modification of the positive electrode active materials.

[0192] In some embodiments, the above positive electrode active materials may be polyanion-type compounds.

[0193] As an optional technical solution of this application, the polyanion-type compound may be Li 1+x Mn 1-y A y [[ID=�6]]P 1-z R z O4; wherein, x is any value within the range of -0.100 to 0.100, y is any value within the range of 0.001 to 0.500, z is any value within the range of 0.001 to 0.100, A includes one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and R includes one or more elements selected from B, S, Si, and N;

[0194] As an optional technical approach in this application, the polyanionic compound can be Li a A e Mn 1-f B f P 1-g C g O 4-n D n Wherein, A includes one or more elements selected from Zn, Al, Na, K, Mg, Nb, Mo, and W; B includes one or more elements selected from Ti, V, Zr, Fe, Ni, Mg, Co, Ga, Sn, Sb, Nb, and Ge; C includes one or more elements selected from B, S, Si, and N; D includes one or more elements selected from S, F, Cl, and Br; a is selected from the range of 0.9 to 1.1, e is selected from the range of 0.001 to 0.1, f is selected from the range of 0.001 to 0.5, g is selected from the range of 0.001 to 0.1, n is selected from the range of 0.001 to 0.1, and the second positive electrode active material is electrically neutral.

[0195] During the charging and discharging process of a battery, Li undergoes insertion / extraction and consumption, resulting in varying molar Li content at different discharge states. In the examples of cathode materials in this application, the molar Li content refers to the initial state of the material, i.e., the state before feeding. When the cathode material is applied to the battery system, the molar Li content changes after charge-discharge cycles.

[0196] In the examples of cathode materials in this application, the molar content of O is only a theoretical value. Oxygen release from the crystal lattice will cause changes in the molar content of oxygen, and the actual molar content of O will fluctuate.

[0197] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0198] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0199] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0200] [Negative electrode plate]

[0201] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector.

[0202] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0203] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0204] In some embodiments, the negative electrode film layer includes a negative electrode active material. The negative electrode active material may be any negative electrode active material known in the art for use in batteries. 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. 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, this application is not limited to these materials, and other conventional 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.

[0205] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0206] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0207] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0208] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0209] In other embodiments, the current collector of the negative electrode sheet typically includes a current collector body and a base coating. The base coating can be disposed on at least one side of the current collector body. The base coating basically does not contain negative electrode active material, and may include a small amount of carbon material. However, the carbon material forms a thin coating and cannot function as a negative electrode active material. In this embodiment, the negative electrode sheet can be an electrode sheet without a negative electrode active material layer. For a negative electrode sheet without a negative electrode active material layer, when the current collector of the negative electrode sheet does not contain a base coating, the film layer can be disposed on the surface of at least one side of the current collector; when the current collector of the negative electrode sheet includes a base coating, the film layer can be disposed on the surface of the base coating away from the current collector.

[0210] In some embodiments, the film layer may further include a binder for fixing the additive to the negative electrode sheet. The type of binder is not particularly limited, and those skilled in the art can choose flexibly according to actual needs.

[0211] Electrolyte

[0212] The electrolyte acts as a conductor of ions between the positive and negative electrodes. In addition to the aforementioned gas-generating agent, the electrolyte in this application also includes an electrolyte salt and a solvent.

[0213] 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.

[0214] 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.

[0215] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0216] [Isolation membrane]

[0217] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0218] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. 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.

[0219] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0220] In some embodiments, the secondary battery may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0221] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch. The material of the soft pack can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0222] In some implementations, the secondary batteries can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0223] Figure 7 shows a battery module 4 as an example. Referring to Figure 7, in the battery module 4, multiple battery cells 10 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 10 can be fixed in place using fasteners.

[0224] Optionally, the battery module 4 may also include a housing with a receiving space in which multiple battery cells 10 are received.

[0225] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0226] Figures 8 and 9 illustrate a battery pack 1 as an example. Referring to Figures 8 and 9, the battery pack 1 may include a battery compartment and multiple battery modules 4 disposed within the battery compartment. The battery compartment includes an upper compartment 2 and a lower compartment 3, with the upper compartment 2 covering the lower compartment 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery compartment.

[0227] The second aspect of this application provides an electrical device.

[0228] The electrical device includes at least one of the secondary battery, battery module, or battery pack provided in this application. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0229] As the electrical device, a secondary battery, battery module, or battery pack can be selected according to its usage requirements.

[0230] Figure 10 shows an example of an electrical device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the secondary battery for this device, a battery pack or battery module can be used.

[0231] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a rechargeable battery as their power source.

[0232]

[0233] Example

[0234] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0235] Example 1

[0236] A secondary battery is provided, prepared according to the following steps:

[0237] [Electrolyte preparation]:

[0238] In an argon-filled glove box, ethylene carbonate (EC), diethyl carbonate (DEC), and methyl ethyl carbonate (EMC) were mixed in a mass ratio of EC:DEC:EMC = 4:2:4. Then, 1.0 mol / L lithium hexafluorophosphate (LiPF6), 2.0 wt% vinylene carbonate (based on the total weight of the electrolyte), and 1.0 wt% biphenyl (based on the total weight of the electrolyte) were added. See Table 1 for details.

[0239] [Preparation of positive electrode sheet]:

[0240] The positive electrode active material lithium iron phosphate (LFP), binder polyvinylidene fluoride (PVDF), and conductive agent conductive carbon black (Super P) are added to N-methylpyrrolidone solvent at a mass ratio of 97:1.5:1.5 and mixed evenly to form a slurry. The slurry is then evenly coated onto aluminum foil, and after drying, cold pressing, slitting, and laser die-cutting, a positive electrode sheet is formed.

[0241] [Preparation of negative electrode sheet]:

[0242] The negative electrode active material graphite, binder styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), and conductive agent conductive carbon black (Super P) are added to deionized water in a mass ratio of 96:1:1:1 to form a slurry. The slurry is then uniformly coated onto copper foil, and after drying, cold pressing, slitting, and laser die-cutting, a negative electrode sheet is formed.

[0243] [Isolation membrane]:

[0244] The separator is a polyethylene separator with a ceramic coating on both sides.

[0245] [Overcharge Protection Mechanism]:

[0246] The overcharge protection mechanism includes an SSD, as shown in Figure 2-5. The thickness of the deformable part is 0.3 mm. The overturning pressure is 0.6 MPa. The deformable part is made of aluminum. The deformable part is circular, with a diameter of 20 mm and a projected area of ​​314 mm². 2 .

[0247] [Battery Assembly]:

[0248] The bare cell is formed by stacking the positive electrode, separator, and negative electrode in that order. The bare cell is then assembled with an overcharge protection mechanism and placed inside an aluminum casing. Finally, after welding and adding electrolyte, a secondary battery is manufactured.

[0249] Example 2

[0250] The difference from Example 1 lies in the content of the gas-generating agent in the electrolyte, as detailed in Table 1.

[0251] Example 3

[0252] The difference from Example 1 lies in the content of the gas-generating agent in the electrolyte, as detailed in Table 1.

[0253] Example 4

[0254] The difference from Example 1 is that the type and content of the gas-generating agent in the electrolyte are different, as detailed in Table 1.

[0255] Example 5

[0256] The difference from Example 1 lies in the content of the gas-generating agent in the electrolyte, as detailed in Table 1.

[0257] Comparative Example 1

[0258] The difference from Example 1 is as follows:

[0259] There is no overcharge protection mechanism; and no gas-generating agent is added to the electrolyte.

[0260] Comparative Example 2

[0261] The difference from Example 1 is that no gas-generating agent is added to the electrolyte.

[0262] [Performance Testing]:

[0263] The performance of the secondary batteries prepared in each embodiment and comparative example was tested using the following methods:

[0264] 1. Charging cutoff time and final battery status test method:

[0265] The fully charged battery was overcharged using a constant current method (0.5 times the battery's rated capacity) until the battery voltage reached 1.5 times its charging cutoff voltage of 3.65V. The charging cutoff time (the time when the voltage is 0V, at which point the secondary battery charging and discharging circuit is open) and the final battery status (whether the battery pressure relief valve is open) were recorded, as detailed in Table 1.

[0266] 2. Battery discharge capacity test method:

[0267] First, discharge the battery to 2.5V using a constant current of 0.33 times its designed capacity. After resting for 30 minutes, charge the battery to 3.65V using a constant current of 0.33 times its rated capacity. Then, switch to constant voltage charging until the current is less than 0.05 times the rated capacity. After resting for 30 minutes, discharge the battery to 2.5V using a constant current of 0.33 times its rated capacity. Record the battery's discharge capacity, as detailed in Table 1.

[0268] The performance test results of each secondary battery are shown in Table 1.

[0269] Table 1

[0270] As can be seen from the data in the table above:

[0271] In all embodiments, the battery state was not open; however, in Comparative Example 1 and Comparative Example 2, the battery state was open. This demonstrates that the secondary battery of this application embodiment has excellent resistance to thermal runaway; the probability of thermal runaway in the secondary battery is extremely low; and the battery has higher reliability.

[0272] This demonstrates that the proposed solution, by adding a gas-generating agent to the electrolyte, causes a polymerization reaction and generates gas when the overcharge voltage reaches the response voltage, thus triggering the overcharge protection mechanism. This allows the secondary battery short-circuit components to activate earlier, advancing the short-circuit protection time and significantly reducing the risk of thermal runaway caused by the decomposition of the battery main material generating a large amount of heat. This is more conducive to reducing the possibility of thermal runaway in secondary batteries.

[0273] Furthermore, as can be seen from the data in the table above, the actual discharge capacity of each embodiment is similar to the design capacity, indicating that the solution of this application can effectively balance the battery capacity while improving the thermal runaway resistance of the secondary battery.

[0274] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A secondary battery characterized by comprising: The secondary battery comprises: a housing having a first surface; an electrode assembly disposed in the housing; an overcharge protection mechanism disposed on the first surface; and an electrolyte comprising a gas generating agent; the gas generating agent is capable of reacting and generating gas when a response voltage is reached; the secondary battery is capable of triggering the overcharge protection mechanism by the gas when an overcharge voltage reaches the response voltage.

2. The secondary battery of claim 1, wherein: the response voltage is greater than an upper limit of an operating voltage of the secondary battery.

3. The secondary battery of claim 1, wherein: the response voltage is 4.5V-5.475V.

4. The secondary battery of any one of claims 1-3, wherein: X comprises at least one of a phenyl group, a cyclohexyl group, a methyl group, a linear alkyl group having 1-6 carbon atoms, or a branched alkyl group. The gas generating agent includes one or more of aromatic compounds having a structure as shown below; 5. The secondary battery of claim 4, wherein: the gas generating agent comprises at least one of biphenyl, cyclohexylbenzene, or tert-butylbenzene.

6. The secondary battery of any one of claims 1-5, wherein: a mass percentage of the gas generating agent in the electrolyte is 0.5%-10%.

7. The secondary battery of any one of claims 1-5, wherein: a mass percentage of the gas generating agent in the electrolyte is 1%-5%.

8. The secondary battery of any one of claims 1-7, further comprising: a first electrode terminal disposed on the first surface in an insulating manner; the overcharge protection mechanism comprises a first deformation member electrically connected to the first surface, the first deformation member being configured to deform to contact the first electrode terminal under the action of gas pressure.

9. The secondary battery of claim 8, wherein: the first electrode terminal comprises a first conductive member and a first pole, the first conductive member and the first pole being connected to each other, the first conductive member being disposed on an outer side of the first surface and being insulated from the first surface, the first pole being electrically connected to the electrode assembly; the first deformation member is configured to deform to contact the first conductive member under the action of gas pressure, so as to electrically connect the first pole to the first surface.

10. The secondary battery of claim 9, further comprising: a first insulating member, at least a portion of the first insulating member being disposed between the first conductive member and the first surface.

11. The secondary battery of claim 10, wherein: an electrical resistance value of the first insulating member is greater than or equal to 200 megaohms.

12. The secondary battery of claim 9, wherein: the first surface has a first electrode lead-out hole, the first pole being disposed in the first electrode lead-out hole; the secondary battery further comprises a second insulating member, at least a portion of the second insulating member being disposed between a hole wall of the first electrode lead-out hole and the first pole.

13. The secondary battery of claim 12, wherein: ​ A first flange is formed on an outer circumferential surface of the first pole. A portion of the second insulating member is positioned between the first flange and an inner surface of the first surface in a thickness direction of the first surface.

14. The secondary battery according to claim 12, wherein The second insulating member has an electrical resistance value of 200 mega ohms or more.

15. The secondary battery according to claim 9, wherein A first protrusion is provided on a surface of the first conductive member facing the first surface, the first protrusion being configured to contact the first deformation member.

16. The secondary battery according to claim 9, wherein The first deformation member includes a first contact portion, a first deformation portion, and a first connection portion. The first deformation portion is provided on an outer circumferential surface of the first contact portion. The first connection portion is provided on an end portion of the first deformation portion that is opposite the first contact portion. The first connection portion is connected to the first surface. The first deformation portion is configured to deform under an air pressure to cause the first contact portion to contact the first conductive member.

17. The secondary battery according to claim 16, wherein The first deformation portion has a thickness that is less than a thickness of the first connection portion, and the first deformation portion has a thickness that is less than a thickness of the first contact portion.

18. The secondary battery according to claim 16, wherein The first deformation portion has a thickness of 0.1 mm to 0.5 mm.

19. The secondary battery according to any one of claims 9 to 18, further comprising: a second electrode terminal that is insulated from the first surface; and a second deformation member that is electrically connected to the first surface, the second deformation member being configured to deform under an air pressure to contact the second electrode terminal.

20. The secondary battery according to claim 19, wherein The second electrode terminal is a negative electrode terminal, and a minimum pressure value at which the second deformation member deforms is greater than a minimum pressure value at which the first deformation member deforms.

21. The secondary battery according to any one of claims 1 to 20, wherein The electrode assembly includes a positive electrode sheet that includes a positive electrode active material, the positive electrode active material including a lithium-containing phosphate having an olivine structure. A secondary battery according to any one of claims 1 to 21.

22. An electrical device, comprising: ​

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