Cylindrical battery cells, batteries and power consumption devices

Abstract

This application relates to a cylindrical battery cell, a battery, and a power consumption device. The cylindrical battery cell comprises a metal housing and an electrolyte, the electrolyte being housed within the metal housing and containing an electrolyte salt, the electrolyte salt comprising a hexafluorophosphate and a sulfonylimide salt, and the molar concentration of the hexafluorophosphate being 0.9 mol / L or less. The reliability and cycle performance of the cylindrical battery cell in the embodiments of this application can be improved.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority of Chinese Patent Application No. 202410536572.5, entitled "Cylindrical Battery Cell, Battery and Power - consuming Device", proposed on April 30, 2024, and all the contents of this application are incorporated herein by reference.

[0002] (Technical Field) This application relates to the field of rechargeable batteries, and particularly to cylindrical battery cells, batteries and power - consuming devices.

Background Art

[0003] Battery cells are widely applied to power - consuming devices such as mobile phones, notebook computers, battery cars, electric vehicles, electric airplanes, electric ships, electric toy cars, electric toy ships, electric toy airplanes and electric tools because of their characteristics such as high capacity.

[0004] With the development of the battery cell field, the requirements for battery performance are gradually increasing, and it is necessary to further improve the use reliability and cycle performance of battery cells.

Summary of the Invention

[0005] This application provides a cylindrical battery cell, a battery and a power - consuming device that can improve the use reliability and cycle performance of the cylindrical battery cell in the embodiments of this application.

[0006] According to a first aspect, the embodiments of this application propose a cylindrical battery cell, which includes a metal housing and an electrolyte. The electrolyte is accommodated in the metal housing. The electrolyte contains an electrolyte salt, and the electrolyte salt contains hexafluorophosphate and sulfonylimide salt. The molar concentration of hexafluorophosphate is 0.9 mol / L or less.

[0007] As a result, the embodiments of this application include a hexafluorophosphate and a sulfonylimide salt, thereby relatively increasing the thermal stability of the electrolyte system and relatively lowering the molar concentration of the hexafluorophosphate, thereby reducing the risk of corrosion of the metal housing by decreasing its corrosive ability to the metal housing, as well as reducing the risk of metal corrosion in the housing and the generation of metal ions. Furthermore, by effectively distributing the forces acting within the system, the metal housing of the cylindrical battery cell is subjected to uniform forces and less prone to deformation, which is advantageous in improving the reliability and cycle performance of the cylindrical battery cell.

[0008] In some embodiments, the molar concentration of hexafluorophosphate is 0.2 mol / L to 0.8 mol / L. When the molar concentration of hexafluorophosphate is within this range, the corrosive effect on the housing can be further reduced, improving the reliability and cycle performance of the cylindrical battery cell.

[0009] In some embodiments, the molar concentration of hexafluorophosphate is 0.3 mol / L to 0.7 mol / L. When the molar concentration of hexafluorophosphate is within this range, the corrosive effect on the housing can be further reduced, improving the reliability and cycle performance of the cylindrical battery cell.

[0010] In some embodiments, the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is 0.06 to 6. When the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is within the above range, the thermal stability of the electrolyte salt is relatively good, acid corrosion due to thermal decomposition is less likely to occur, and the electrochemical stability of the electrolyte salt is also relatively good, further improving the stability of the electrolyte salt and enhancing the reliability and cycle performance of the battery cell.

[0011] In some embodiments, the ratio of the molar concentration of sulfonylimid salt to the molar concentration of hexafluorophosphate is 0.2 to 2. When the ratio of the molar concentration of sulfonylimid salt to the molar concentration of hexafluorophosphate is within the above range, the stability of the electrolyte salt can be further enhanced, improving the reliability of the battery cell and its cycle performance.

[0012] In some embodiments, the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is 0.3 to 1.5. When the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is within the above range, the stability of the electrolyte salt can be further enhanced, improving the reliability of the battery cell and its cycle performance.

[0013] In some embodiments, the molar concentration of the electrolyte salt is between 0.5 mol / L and 2 mol / L. When the molar concentration of the electrolyte salt is within this range, it is advantageous to further enhance the stability of the electrolyte salt, thereby improving the reliability and cycle performance of the battery cell, and to improve the dynamic performance of the battery cell by enhancing the liquid phase transport capacity of active ions.

[0014] In some embodiments, the molar concentration of the electrolyte salt is between 0.6 mol / L and 1.5 mol / L. A molar concentration within this range is advantageous for further improving the dynamic performance of the battery cell.

[0015] In some embodiments, the metal housing includes a housing body and a film layer, the film layer being installed on at least the surface of the housing body facing the electrolyte, and the matrix element of the film layer is nickel. The matrix element of the film layer being nickel significantly enhances the acid corrosion resistance of the film layer, and if the cylindrical battery cell further contains hexafluorophosphate, the nickel element can effectively enhance the acid corrosion resistance of the film layer and reduce the risk of metal corrosion in the housing and the generation of metal ions, thereby being advantageous in improving the reliability and cycle performance of the cylindrical battery cell.

[0016] In some embodiments, the film layer thickness is 1.5 μm to 6.0 μm. When the film layer thickness is within this range, it is advantageous to increase the corrosion resistance of the film layer, thereby improving the reliability and cycle performance of cylindrical battery cells.

[0017] In some embodiments, the film layer thickness is 2.0 μm to 4.0 μm. When the film layer thickness is within this range, it is advantageous to improve the reliability and cycle performance of cylindrical battery cells by increasing the corrosion resistance of the film layer.

[0018] In some embodiments, the mass content of nickel in the film layer is 70 wt% to 100 wt%. When the mass content of nickel is within this range, the corrosion resistance of the film layer can be enhanced, thereby improving the reliability and cycle performance of cylindrical battery cells.

[0019] In some embodiments, the mass content of nickel in the film layer is 80 wt% to 95 wt%. When the mass content of nickel is within this range, the corrosion resistance of the film layer can be enhanced, thereby improving the reliability and cycle performance of cylindrical battery cells.

[0020] In some embodiments, the film layer further contains iron elements, with the mass content of iron elements in the film layer being 0.1 wt% to 10 wt%, and selectively 1 wt% to 5 wt%. When the mass content of iron elements is within the above range, the conductivity of the housing can be effectively improved, which is advantageous for electron transport.

[0021] In some embodiments, the film layer further contains carbon, and the mass content of carbon in the film layer is 0.1 wt% to 15 wt%, selectively 4 wt% to 12 wt%. When the mass content of carbon is within the above range, the conductivity of the housing can be effectively improved, which is advantageous for electron transport.

[0022] In some embodiments, the matrix material of the housing body is steel. Housing bodies made of the above material have relatively good mechanical strength, are less prone to deformation, and can further improve the reliability of use of cylindrical battery cells.

[0023] In some embodiments, the sulfonylimide salt contains the anion represented by formula A, [ka] In formula A, R1 and R2 each independently contain a halogen atom or a C1-C6 haloalkyl group.

[0024] As a result, the thermal stability of the sulfonylimide salt of the above material in the embodiment of this application is relatively excellent, which reduces corrosion of the housing by the electrolyte salt and is advantageous in improving the reliability and cycle performance of the battery cell.

[0025] In some embodiments, the halogen atom includes a fluorine atom.

[0026] In some examples, the C1-C6 haloalkyl group includes a C1-C6 fluoroalkyl group.

[0027] In some examples, R1 and R2 each independently contain a fluorine atom or a C1-C3 fluoroalkyl group.

[0028] In some embodiments, the anion represented by formula A includes one or more of the anions represented by formula A-1 to formula A-5. [ka]

[0029] In some embodiments, the anion represented by formula A includes one or more of the anions represented by formula A-1 to formula A-2. [ka]

[0030] In some embodiments, the cylindrical battery cell includes an electrode assembly, the electrode assembly includes a positive electrode plate, the positive electrode plate includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, and the positive electrode active material includes a layered transition metal oxide. The sulfonyl imide salt can improve the interfacial stability between the layered transition metal oxide and the electrolyte, reduce the risk generated by side reactions, and improve the cycle performance of the cylindrical battery cell.

[0031] In some embodiments, the layered transition metal oxide has the chemical formula Li a Ni b Co c M d O e A f and includes at least one of a compound of and its modified compound, where 0.8 ≦ a ≦ 1.2, 0.3 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes at least one of N, F, S, and Cl. The sulfonyl imide salt can improve the interfacial stability between the layered transition metal oxide and the electrolyte, reduce the risk generated by side reactions, and improve the cycle performance of the cylindrical battery cell.

[0032] In some embodiments, 0.5 ≦ b < 1, and optionally, 0.75 ≦ b ≦ 0.98. The sulfonyl imide salt can improve the interfacial stability between the layered transition metal oxide and the electrolyte, reduce the risk generated by side reactions, and improve the cycle performance of the cylindrical battery cell.

[0033] In some embodiments, the electrolyte includes a chain ester solvent, and the mass content of the chain ester solvent in the electrolyte is 25.5 wt% or more.

[0034] As a result, the mass content of the linear ester solvent in the embodiments of this application is 25.5 wt% or more, which is advantageous in improving the magnification performance of the battery cell by relatively increasing the conductivity of the electrolyte, enhancing the liquid phase transport capacity of active ions, and improving the rapid charging and discharging capacity of the battery cell.

[0035] In some examples, the mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%. When the mass content of the linear ester solvent is within this range, the magnification performance and reliability of the battery cell can be further improved, and the cycle performance of the battery cell can also be further improved.

[0036] In some examples, the mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 70 wt%. When the mass content of the linear ester solvent is within this range, the magnification performance and reliability of the battery cell can be further improved, and the cycle performance of the battery cell can also be further improved.

[0037] In some examples, the mass content of the linear ester solvent in the electrolyte is 42.5 wt% to 70 wt%. When the mass content of the linear ester solvent is within this range, the magnification performance and reliability of the battery cell can be further improved, and the cycle performance of the battery cell can also be further improved.

[0038] In some embodiments, the linear ester solvent contains linear carbonate, and the mass content of linear carbonate in the electrolyte is 4 wt% to 70 wt%. When the mass content of linear carbonate is within the above range, the conductivity of the electrolyte can be improved, the liquid phase transport dynamics performance of the electrolyte can be enhanced, and the magnification performance and operational reliability of the battery cell can be further improved.

[0039] In some embodiments, the mass content of the chain carbonate in the electrolyte is 4 wt% to 42.5 wt%. When the mass content of the chain carbonate is within the above range, the conductivity of the electrolyte can be improved, the liquid-phase transport kinetics performance of the electrolyte can be enhanced, and the rate performance and usage reliability of the battery cell can be further improved.

[0040] In some embodiments, the chain carbonate contains a compound represented by Formula I,

Chemical formula

[0041] Thereby, when the chain carbonate in the embodiments of the present application is the above material, the rate performance and usage reliability of the battery cell can be further improved.

[0042] In some embodiments, R 11 and R 12 each independently contain a C1-C3 alkyl group or a C1-C3 fluoroalkyl group. <l

[0043] In some embodiments, the chain carbonate contains one or more of the compounds represented by Formula I-1 to Formula I-6.

Chemical formula

[0044] In some embodiments, the chain carbonate contains the compound represented by Formula I-1.

Chemical formula

[0045] In some examples, the linear ester solvent further contains linear carboxylic acid esters, with the mass content of the linear carboxylic acid ester in the electrolyte being 4 wt% to 70 wt%. By using linear carboxylic acid esters and linear carbonates in combination, the conductivity of the electrolyte can be improved, the liquid phase transport dynamics performance of the electrolyte can be enhanced, and the magnification performance and operational reliability of the battery cell can be further improved.

[0046] In some embodiments, the mass content of the linear carboxylic acid ester in the electrolyte is 8.5 wt% to 60 wt%. When the mass content of the linear carboxylic acid ester in the electrolyte is within this range, the conductivity of the electrolyte can be improved, the liquid phase transport dynamics performance of the electrolyte can be enhanced, and the magnification performance and operational reliability of the battery cell can be further improved.

[0047] In some examples, the linear carboxylic acid ester includes the compound represented by formula II, [ka] In Equation II, R 21 It contains a hydrogen atom, a halogen atom, a C1-C3 alkyl group, or a C1-C3 haloalkyl group. R 22 Contains C1-C3 alkyl groups or C1-C3 haloalkyl groups.

[0048] As a result, by using a combination of the linear carboxylic acid ester and linear carbonate materials described above in the embodiments of this application, the magnification performance and reliability of the battery cell can be further improved.

[0049] In some embodiments, R 21 It contains a hydrogen atom, a fluorine atom, and a C1-C3 alkyl group or a C1-C3 fluoroalkyl group.

[0050] In some embodiments, R 22 This includes C1-C3 alkyl groups or C1-C3 fluoroalkyl groups.

[0051] In some examples, the linear carboxylic acid ester comprises one or more of the compounds represented by formula II-1 to formula II-6. [ka]

[0052] In some examples, the linear carboxylic acid ester comprises one or more of the compounds represented by formula II-2 and the compounds represented by formula II-3.

[0053] In some examples, the linear carbonate comprises the compound represented by formula I-1. [ka] The mass content of the compound represented by formula I-1 in the electrolyte is 8.5 wt% to 35 wt%, The chain-like carboxylic acid ester includes the compound represented by formula II-2 and the compound represented by formula II-3, and the mass content of the compound represented by formula II-2 and the compound represented by formula II-3 in the electrolyte is 20 wt% to 55 wt%.

[0054] In some embodiments, the metal housing includes a case and an end cap, the case includes a side wall and an end wall connected to the side wall, the case has an opening, the end cap is connected to the side wall and covers the opening, and the end cap and the end wall face each other along the axial direction of the cylindrical battery cell.

[0055] In some embodiments, the matrix material of the sidewall is steel, and the thickness of the sidewall is 0.30 mm to 1.2 mm. When the thickness of the sidewall is within the above range, the strength of the sidewall is relatively high, it has a stronger pressure resistance, effectively mitigates the risk of deformation of the sidewall, and reduces the risk of expansion of the battery cell, thereby improving the reliability of the battery cell.

[0056] In some embodiments, the sidewall thickness is 0.30 mm to 0.55 mm. When the sidewall thickness is within this range, the reliability of the battery cell can be improved by reducing the risk of battery cell swelling.

[0057] In some embodiments, the side wall and the end wall are integrally formed structures.

[0058] In some embodiments, the end cap is provided with a pressure relief mechanism. The pressure relief mechanism deforms due to the action of internal pressure, connecting the internal and external spaces of the metal housing and allowing gases inside the metal housing to be released, thereby reducing the risk of the battery cell exploding.

[0059] In some embodiments, the pressure relief mechanism includes a weak point, the matrix material of the weak point includes steel, and the thickness of the weak point is 0.01 mm to 0.3 mm. When the thickness of the weak point is within the above range, the strength of the weak point is relatively high, and it has a stronger pressure resistance capacity, which can effectively increase the pressure resistance capacity of the battery cell and improve the reliability of the battery cell in use.

[0060] In some embodiments, the thickness of the vulnerable area is 0.05 mm to 0.2 mm. When the thickness of the vulnerable area is within this range, the reliability of the battery cell can be further improved.

[0061] In some embodiments, the end cap is provided with a recess, the bottom wall of which is a weak point. Such a structural form is simple and convenient to manufacture.

[0062] In some embodiments, the battery cell further includes electrode terminals mounted on the end wall, and the battery cell includes an electrode assembly housed in a case, the electrode assembly including a first tab and a second tab of opposite polarity, the first tab being electrically connected to the end wall and the second tab being electrically connected to the electrode terminal.

[0063] In some embodiments, the axial size of the metal housing is 1.3 to 2.5 times the radial size of the metal housing relative to the cylindrical battery cell.

[0064] In some embodiments, the size of the metal housing along the axial direction of the cylindrical battery cell is 50mm to 150mm.

[0065] In some embodiments, the size of the metal housing along the radial direction of the cylindrical battery cell is 40mm to 80mm.

[0066] According to a second aspect, the embodiments of the present application further propose a battery comprising a cylindrical battery cell of any one embodiment of the first aspect of the present application.

[0067] According to a third aspect, an embodiment of the present application further proposes a power consumption device which includes a battery of any one embodiment of the second aspect of the present application. [Brief explanation of the drawing]

[0068] To more clearly illustrate the technical concept of the embodiments of this application, the following is a brief introduction to the drawings that may be used in the embodiments of this application. It is obvious that the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without expending any creative effort. [Figure 1] This is a schematic diagram of the structure of a vehicle according to several embodiments of this application. [Figure 2] This is a schematic diagram of a battery exploded according to some embodiments of this application. [Figure 3] Figure 2 is a schematic diagram of the battery module after disassembly. [Figure 4] This is a schematic diagram of the structure of a cylindrical battery cell according to some embodiments of this application. [Figure 5] This is a schematic exploded view of a cylindrical battery cell according to some embodiments of this application. [Figure 6]This is a schematic cross-sectional view of a cylindrical battery cell according to several embodiments of this application. [Figure 7] Figure 6 is an enlarged schematic diagram of point A in the cylindrical battery cell. The drawing may not necessarily be to the actual scale. [Modes for carrying out the invention]

[0069] The following describes in detail embodiments specifically disclosing the cylindrical battery cell, battery and power consumption device of this application, with appropriate reference to the drawings. However, unnecessary detailed explanations may be omitted. For example, detailed explanations of well-known matters and redundant explanations of structures that are actually the same may be omitted. This is to avoid making the following explanation unnecessarily long and to make it easily understandable to those skilled in the art. The drawings and the following explanation are provided to enable those skilled in the art to fully understand this application and do not limit the topics described in the claims.

[0070] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is limited by selecting one lower limit and one upper limit, which define the boundary of a particular range. The range thus limited may or may not include the endpoints, and any combination is possible, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 can also be assumed. Furthermore, if the minimum range values ​​are listed as 1 and 2, and the maximum range values ​​are listed as 3, 4 and 5, then the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 can all be assumed. In this application, unless otherwise specified, the numerical range “a-b” represents an abbreviated expression for any combination of real numbers a-b, where a and b are both real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 to 5" have already been listed in this specification, and "0 to 5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter is described as an integer ≥ 2, it is equivalent to disclosing that this parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0071] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical inventions.

[0072] Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical concepts.

[0073] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably in order. For example, if a method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, if a mentioned method may further include step (c), it means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), and so on.

[0074] The “Examples” as used in this application mean that certain features, structures, or characteristics described in conjunction with the Examples may be included in at least one Example of this application. The occurrence of this phrase in each location in the specification does not necessarily refer to the same Example, nor does it mean that each Example is mutually exclusive or alternative to the others.

[0075] In the description of this application, unless otherwise specifically defined or limited, the terms “attachment,” “connection,” “connection,” and “installation” should be understood in a broad sense. For example, a fixed connection may be a detachable connection, an integral connection, a direct connection, an indirect connection via an intermediate medium, or internal communication between two elements. A person skilled in the art will be able to understand the specific meaning of these terms in this application depending on the specific circumstances.

[0076] In this application, the terms "and / or" merely describe the relationship between related objects, indicating that three relationships are possible. For example, A and / or B may represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the character " / " generally indicates that the preceding and succeeding related objects are in an "or" relationship.

[0077] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the dimensions such as thickness, length, and width of various components in the embodiments of this application shown in the drawings, and the overall dimensions such as thickness, length, and width of the integrated device, are illustrative and should not constitute any limitation to this application.

[0078] In this application, "multiple" refers to two or more (including two). In the embodiments of this application, the battery cell may be a secondary battery, which is a battery cell that can be used continuously by activating the active material through a charging method after the battery cell has been discharged.

[0079] Battery cells may include, but are not limited to, lithium-ion battery cells, sodium-ion battery cells, sodium-lithium-ion battery cells, lithium metal battery cells, sodium metal battery cells, lithium-sulfur battery cells, magnesium-ion battery cells, nickel-metal hydride battery cells, nickel-cadmium battery cells, lead-acid battery cells, etc.

[0080] For example, a battery cell may be a cylindrical battery cell, which is a battery cell whose external shape is cylindrical or similar to a cylindrical structure.

[0081] The batteries referred to in the embodiments of this application refer to a single physical module comprising one or more battery cells to provide higher voltage and capacity.

[0082] In some embodiments, the battery may be a battery module, and if there are multiple battery cells, the multiple battery cells are arranged and fixed together to form a single battery module.

[0083] In some embodiments, the battery may be a battery pack, which includes a housing and battery cells, and the battery cells or battery modules are housed in the housing.

[0084] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, part of the housing may be at least part of the vehicle's floor, or part of the housing may be at least part of the vehicle's cross members and side members.

[0085] In some embodiments, the battery may be an energy storage device. The energy storage device may include an energy storage container, an energy storage electrical cabinet, and the like.

[0086] A battery cell comprises an electrolyte and a housing. The electrolyte contains an electrolyte salt, such as hexafluorophosphate, which has relatively poor thermal stability and readily decomposes to produce hydrofluoric acid (HF). HF can corrode the housing, especially metal housings, potentially jeopardizing the reliability of the cylindrical battery cell. Furthermore, metal ions generated by the corrosion of the metal housing may be present in the electrolyte, negatively impacting the battery cell and potentially degrading its cycle performance and storage capabilities.

[0087] In view of this, the embodiment of the present application proposes a cylindrical battery cell in which the housing of the cylindrical battery cell is a metal housing, and the electrolyte salt in the electrolyte solution contains a hexafluorophosphate and a sulfonylimide salt. By introducing the sulfonylimide salt, the thermal stability of the electrolyte system is made relatively high, and the molar concentration of the hexafluorophosphate is made relatively low, for example, to 0.9 mol / L or less, thereby reducing the corrosive capacity to the metal housing, thereby reducing the risk of the metal housing being corroded and reducing the risk of the metal in the housing corroding and generating metal ions, which is advantageous in improving the reliability of use and cycle performance of the cylindrical battery cell.

[0088] The cylindrical battery cell described in the embodiments of this application is applicable to batteries and power consumption devices using batteries.

[0089] The cylindrical battery cells, batteries, and power consumption devices disclosed in the embodiments of this application may be used in power consumption devices that use batteries as a power source or in various energy storage systems that use batteries as energy storage elements. Power consumption devices may include, but are not limited to, mobile phones, tablet devices, laptop computers, electric toys, power tools, battery-powered cars, electric vehicles, steamships, and aerospace vehicles. Here, electric toys may include stationary or portable electric toys, such as game consoles, electric car toys, electric steamship toys, and electric airplane toys, and aerospace vehicles may include airplanes, rockets, space shuttles, and spacecraft.

[0090] For the sake of explanation, the following embodiments will be described using a vehicle as the power consumption device.

[0091] Figure 1 is a schematic diagram of the structure of a vehicle according to some embodiments of this application.

[0092] As shown in Figure 1, a battery 2 is installed inside the vehicle 1, and the battery 2 may be installed at the bottom, head, or tail of the vehicle 1. The battery 2 may be used to power the vehicle 1, for example, the battery 2 may also be used as the operating power source for the vehicle 1.

[0093] Vehicle 1 may further include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, to meet the power consumption requirements for starting, navigating, and driving Vehicle 1.

[0094] In some embodiments of this application, the battery 2 may provide driving power to the vehicle 1 not only as an operating power source for the vehicle 1, but also as a driving power source for the vehicle 1, in place of or in place of fuel or natural gas.

[0095] Figure 2 is a schematic exploded view of a battery according to some embodiments of the present application. As shown in Figure 2, the battery 2 includes a housing 5 and a cylindrical battery cell (not shown in Figure 2), the cylindrical battery cell being housed inside the housing 5.

[0096] The housing 5 is used to house cylindrical battery cells, and the housing 5 may have various structures. In some embodiments, the housing 5 may include a first housing portion 5a and a second housing portion 5b, the first housing portion 5a and the second housing portion 5b covering each other, and the first housing portion 5a and the second housing portion 5b jointly define a housing space 5c for housing cylindrical battery cells. The second housing portion 5b may be a hollow structure with one end open, the first housing portion 5a is a plate-like structure, the first housing portion 5a is installed over the open side of the second housing portion 5b to form a housing 5 having a housing space 5c, and both the first housing portion 5a and the second housing portion 5b may be hollow structures with one side open, the open side of the first housing portion 5a is installed over the open side of the second housing portion 5b to form a housing 5 having a housing space 5c. Of course, the first housing portion 5a and the second housing portion 5b may have various shapes, such as a cylinder or a rectangular parallelepiped.

[0097] To improve the sealing performance after connecting the first housing portion 5a and the second housing portion 5b, a sealing material, such as a sealant or a sealing ring, may be installed between the first housing portion 5a and the second housing portion 5b.

[0098] If the first housing portion 5a is installed over the top of the second housing portion 5b, the first housing portion 5a may be called the upper housing cover, and the second housing portion 5b may be called the lower housing.

[0099] In battery 2, there may be one cylindrical battery cell or multiple cylindrical battery cells. If there are multiple cylindrical battery cells, the multiple cylindrical battery cells may be connected in series, in parallel, or in series-parallel, where series-parallel connection means that the multiple cylindrical battery cells are connected in both series and parallel. The multiple cylindrical battery cells may be directly connected in series, in parallel, or in series-parallel before the entire assembly of the multiple cylindrical battery cells is housed inside the housing 5. Of course, the multiple cylindrical battery cells may first be connected in series, in parallel, or in series-parallel to form a battery module 6, and then the multiple battery modules 6 may be further connected in series, in parallel, or in series-parallel to form a single whole, which is then housed inside the housing 5.

[0100] A cylindrical battery cell may be the smallest unit that makes up a battery.

[0101] Figure 3 is a schematic diagram of the battery module shown in Figure 2.

[0102] In some embodiments, as shown in Figure 3, there are multiple cylindrical battery cells 7, and these multiple cylindrical battery cells 7 are first connected in series, in parallel, or in series-parallel to form a battery module 6. The multiple battery modules 6 are further connected in series, in parallel, or in series-parallel to form a single unit, which is then housed inside a housing.

[0103] Multiple cylindrical battery cells 7 in the battery module 6 may be electrically connected via busbar members to achieve parallel, series, or series-parallel connection of the multiple cylindrical battery cells 7 in the battery module. There may be one or more busbar members, and each busbar member is used to electrically connect at least two cylindrical battery cells.

[0104] Figure 4 is a schematic diagram of the structure of a cylindrical battery cell according to some embodiments of this application, and Figure 5 is a schematic exploded view of the cylindrical battery cell shown in Figure 4.

[0105] As shown in Figures 4 and 5, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a metal housing 20, the electrode assembly 10 being housed inside the metal housing 20.

[0106] The metal housing 20 has a cylindrical structure, and the metal housing 20 includes a case 21, which has a cylindrical structure, and the corresponding electrode assembly 10 also has a cylindrical structure.

[0107] In some embodiments, the size of the metal housing 20 along the axial direction X of the cylindrical battery cell 7 is 1.3 to 2.5 times the size of the metal housing 20 along the radial direction Y of the cylindrical battery cell 7, for example, 1.3 times, 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, or any two of the above values. When the metal housing 20 satisfies the above size requirements, the volume expansion of the electrode assembly 10 can be effectively restrained, thereby making the distribution of the extruding force on the metal housing 20 relatively uniform, reducing the likelihood of deformation of the metal housing 20, and improving the reliability of use of the cylindrical battery cell 7.

[0108] For example, the size of the metal housing 20 along the axial direction X is in the range of 50mm to 150mm, for example, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm, 150mm, or any two of the above values.

[0109] For example, the size of the metal housing 20 along the radial direction Y is in the range of 40mm to 80mm, for example, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, or any two of the above values.

[0110] The electrode assembly 10 includes a positive electrode and a negative electrode. During the charging and discharging process of the cylindrical battery cell 7, active ions (e.g., lithium ions) reciprocate between the positive and negative electrodes, undergoing intercalation and deintercalation. Selectively, the electrode assembly 10 further includes a separator member placed between the positive and negative electrodes, which can reduce the risk of short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0111] In some embodiments, the positive electrode may be a positive electrode plate, which may include a positive electrode current collector and a positive electrode film layer placed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0112] For example, a positive electrode current collector has two opposing surfaces in its own thickness direction, and the positive electrode film layer is placed on one or both of the two opposing surfaces of the positive electrode current collector.

[0113] For example, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, as the metal foil sheet, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, titanium, silver-surfaced aluminum or stainless steel may be used. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0114] For example, if the cylindrical battery cell 7 in the embodiment of this application is a lithium-ion battery, the positive electrode active material may include at least one of the following materials: phosphate, layered transition metal oxide, and their respective modified compounds. Selectively, the positive electrode active material may include layered transition metal oxide and their respective modified compounds, which is advantageous for increasing the energy density of the cylindrical battery cell 7. 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 individually or in combination of two or more.

[0115] Examples of phosphates may include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0116] The layered transition metal oxide includes at least one of a compound of the general formula Li a Ni b Co c M d O e A f and its modified compound. 0.8 ≦ a ≦ 1.2, 0.3 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes at least one of N, F, S, and Cl. Optionally, 0.5 ≦ b < 1, and further optionally, 0.75 ≦ b ≦ 0.98.

[0117] Examples of layered transition metal oxides include lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which may be abbreviated as NCM 622(It may also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (It may also be abbreviated as LiNi) 0.9 Co 0.05 Mn 0.05 O2 (may be abbreviated as Ni90), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.80 Co 0.15 Al 0.05 It may contain, but is not limited to, at least one of O2 and its modified compounds.

[0118] If the cylindrical battery cell 7 of the embodiment of this application is a sodium-ion battery, the positive electrode active material may include, but is not limited to, at least one of a sodium-containing transition metal oxide, a polyanionic material (e.g., phosphate, fluorophosphate, pyrophosphate, sulfate, etc.), and a Prussian blue-based material.

[0119] For example, the positive electrode active materials used in sodium-ion batteries are NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, and NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, general formula X p M' q (PO4) r O x Y 3-x It may contain at least one of the following materials. General formula X p M' q (PO4) r O x Y 3-x In 0 <p≦4、0<q≦2、1≦r≦3、0≦x≦2であり、Xは、H + Li + na+ , K + and NH4 + It contains at least one of the following, where M' is a transition metal cation, selectively at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halogen anion, selectively at least one of F, Cl and Br.

[0120] In the embodiments of this application, the modifying compound for each of the positive electrode active materials may be a doping modification and / or surface coating modification of the positive electrode active material, such as a carbon coating modification or a high-speed ion conductor coating modification.

[0121] The cylindrical battery cell 7 undergoes desorption and consumption of active ions, such as Li, during the charge and discharge process, resulting in different molar Li content when the cylindrical battery cell 7 is discharged to different states. In the enumeration of positive electrode active materials in the embodiments of this application, the molar Li content refers to the initial state of the material, i.e., the state before material input. As the positive electrode active material is used in the battery system and undergoes charge and discharge cycles, changes in the molar Li content may occur.

[0122] In the enumeration of positive electrode active materials in the embodiments of this application, the molar content of oxygen (O) is merely a theoretical value, and the molar content of oxygen (O) changes due to oxygen release from the crystal lattice, so in reality, the molar content of oxygen (O) fluctuates.

[0123] In the embodiments of this application, the elemental content in the positive electrode active material is in the sense known in the art and can be detected using instruments and methods known in the art, for example, by inductively coupled plasma atomic emission spectroscopy, referring to EPA 6010D-2014, and measured using plasma atomic emission (ICP-OES, instrument model: Thermo ICAP7400). First, 0.4 g of positive electrode active material is weighed and 10 ml of (50% concentration) aqua regia is added thereto. Then it is left on a plate at 180°C for 30 min. After digestion on the plate, the volume is reduced to 100 mL and a quantitative test is performed using the standard curve method.

[0124] In some embodiments, the positive electrode may be made of foamed metal. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. When foamed metal is used as the positive electrode, a positive electrode film layer may or may not be placed on the surface of the foamed metal. For example, the interior of the foamed metal may be filled with and / or deposited with a lithium source material, potassium metal, or sodium metal, and the lithium source material is lithium metal and / or a lithium-rich material.

[0125] In some embodiments, the cathode film layer further selectively contains a cathode conductive agent. The embodiments of this application are not particularly limited to the type of cathode conductive agent, and as an example, the cathode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the cathode conductive agent in the cathode film layer is ≤5 wt%.

[0126] In some embodiments, the cathode film layer further selectively includes a cathode adhesive. The embodiments of this application are not particularly limited to the type of cathode adhesive, and for example, the cathode adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene ternpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene ternpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins. In some embodiments, the mass content of the cathode adhesive in the cathode film layer is ≤5 wt%.

[0127] The positive electrode film layer is generally obtained by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, a selective conductive agent, a selective adhesive, and any other components in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP).

[0128] In some embodiments, the negative electrode may be a negative electrode plate, which may include a negative electrode current collector and a negative electrode film layer placed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0129] For example, the negative electrode current collector has two opposing surfaces in its own thickness direction, and the negative electrode film layer is placed on one or both of the two opposing surfaces of the negative electrode current collector.

[0130] For example, the negative electrode current collector may be a metal foil sheet, foamed metal, or a composite current collector. For example, as the metal foil sheet, silver-surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium may be used. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon. The composite current collector may include a polymer material base layer and a metal layer. The composite current collector may be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, or polyethylene).

[0131] For example, the negative electrode active material may be a negative electrode active material used in cylindrical battery cells 7 known in the art. For example, the negative electrode active material may include at least one of the following materials: carbon material (for example, the carbon material includes at least one of artificial graphite, natural graphite, soft carbon, and hard carbon), silicon-based material, tin-based material, and lithium titanate. The silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material may include at least one of elemental tin, tin oxide, and tin alloy. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may also be used. These negative electrode film layers may be used individually or in combination of two or more.

[0132] In some embodiments, the negative electrode active material includes a silicon element, which may exist in the form of a silicon-based material, for example, the silicon-based material may include at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The introduction of a silicon element can increase the energy density of the cylindrical battery cell 7.

[0133] In some embodiments, the mass content of the silicon element in the negative electrode film layer is 1 wt% to 32 wt%, selectively 2 wt% to 19 wt%, and more selectively 6 wt% to 13 wt%. In a cylindrical battery cell system, when the mass content of the silicon element is within the above range, the energy density of the cylindrical battery cell 7 can be increased. Furthermore, the cylindrical metal housing 20 acts as a restraining force on the expanded electrode assembly 10, thereby making the distribution of the force acting on the metal housing 20 by the electrode assembly 10 relatively uniform and making deformation of the metal housing 20 less likely. This enhances the structural stability of the metal housing 20 and, consequently, improves the reliability of the cylindrical battery cell 7.

[0134] In the embodiments of this application, the mass content of the silicon element in the negative electrode film layer is as known in the art and can be detected using instruments and methods known in the art. For example, the negative electrode plate is immersed in a solvent, such as water, to separate the negative electrode active material from the negative electrode current collector, and the negative electrode active material is obtained by suction filtration. The silicon element content of the negative electrode active material can then be obtained using an inductively coupled plasma-atomography spectrometer, model ICAP7400, manufactured by Thermo Fisher Scientific, USA, in reference to the GB / T30902-2014 standard.

[0135] In some embodiments, the negative electrode film layer further selectively contains a negative electrode conductive agent. The embodiments of this application are not particularly limited to the type of negative electrode conductive agent, and for example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers. In some embodiments, the mass content of the negative electrode conductive agent in the negative electrode film layer is ≤5 wt%.

[0136] In some embodiments, the negative electrode film layer further selectively includes a negative electrode adhesive. The embodiments of this application are not particularly limited to the type of negative electrode adhesive, and as an example, the negative electrode adhesive may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic acid resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS). In some embodiments, the mass content of the negative electrode adhesive in the negative electrode film layer is ≤5%.

[0137] In some embodiments, the negative electrode film layer further selectively contains other additives. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC-Na) or PTC thermistor materials. In some embodiments, the mass content of the other additives in the negative electrode film layer is ≤2 wt%.

[0138] In some embodiments, the material of the positive electrode current collector may be aluminum, and the material of the negative electrode current collector may be copper.

[0139] In some embodiments, the separator member includes a separator. This application is not particularly limited to the type of separator, and any known porous separator having good chemical and mechanical stability may be selected.

[0140] The embodiments of this application are not particularly limited to the type of separator, and any known porous structure separator having good chemical and mechanical stability may be selected.

[0141] In some embodiments, the separator material may include one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film, and is not particularly limited. When the separator is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0142] In some embodiments, the separator may include a porous base film and a coating placed on at least one side of the porous base film, the coating may include at least one of inorganic particles or organic particles.

[0143] The porous base film may contain one or more of polyethylene and polypropylene.

[0144] Inorganic particles have relatively good heat resistance and can improve the overall heat resistance of the separator. Within the operating voltage range of the sodium-ion battery, the inorganic particles hardly undergo oxidation and redox reactions with metal dendrites; in other words, the inorganic particles are configured so that oxidation and redox reactions with alkali metals and / or alkaline earth metals do not occur under the nominal voltage of the sodium-ion battery.

[0145] In some examples, the inorganic particles include one or more of the following: boehmite γ-AlOOH, aluminum oxide Al2O3, aluminum hydroxide Al(OH)3, barium sulfate BaSO4, magnesium oxide MgO, magnesium hydroxide Mg(OH)2, calcium oxide CaO, cerium oxide CeO2, zirconium titanate SrTiO3, barium titanate BaTiO3, and magnesium fluoride MgF2.

[0146] In some embodiments, the organic particles include at least one of the following: polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramid, polyamide-imide, polyimide, copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0147] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte.

[0148] During the charging and discharging process of a battery cell, active ions reciprocate between the positive and negative electrodes, undergoing intercalation and deintercalation, while the electrolyte plays a role in conducting these active ions between the positive and negative electrodes. The embodiments of this application are not particularly limited to the type of electrolyte and can be selected according to actual needs.

[0149] The electrolyte solution contains an electrolyte salt and a solvent. The types of electrolyte salt and solvent are not specifically limited and can be selected according to actual needs.

[0150] In some embodiments, the electrolyte further selectively includes additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, additives that improve the battery's high-temperature performance, and additives that improve the battery's low-temperature power performance.

[0151] For example, the additive includes at least one of the following: cyclic carbonate compounds containing unsaturated bonds, sulfate ester compounds, sulfite ester compounds, sultone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds, isocyanate compounds, phosphazene compounds, acid anhydrides, cyclic acid anhydride compounds, phosphite ester compounds, phosphate ester compounds, boric acid esters, and carboxylic acid ester compounds.

[0152] As shown in Figures 4 and 5, in some embodiments, the electrode assembly 10 may be a wound structure or a laminated structure, and selectively, the electrode assembly 10 is a wound structure. The positive electrode plate and the negative electrode plate are wound into a wound structure.

[0153] For example, multiple positive and negative electrode plates may be installed, and multiple positive and negative electrode plates may be stacked alternately.

[0154] In some embodiments, the metal housing 20 includes a case 21 and an end cap 22, the case 21 having an opening, and the end cap 22 being used to cover the opening.

[0155] The case 21 is a component that works in cooperation with the end cap 22 to form an internal cavity for the cylindrical battery cell 7, and the formed internal cavity may be used to house the electrode assembly 10, electrolyte, and other components.

[0156] The case 21 and the end cap 22 may be separate components. For example, an opening may be provided on the case 21, and the end cap 22 may be placed over the opening to form the internal cavity of the cylindrical battery cell 7.

[0157] The end cap 22 is connected to the case 21 by welding, bonding, locking, or other means.

[0158] The case 21 may have an opening at one end or at both ends. In some examples, the case 21 may have an opening on one side, and one end cap 22 may be provided to cover the case 21. In some other examples, the case 21 may have an opening on both sides, and two end caps 22 may be provided, each covering one of the two openings in the case 21.

[0159] In some embodiments, the case 21 includes a side wall 212 and an end wall 211 connected to the side wall 212, the end wall 211 and the end cap 22 facing each other along the axial direction of the cylindrical battery cell 7, the end cap 22 being sealedly connected to the side wall 212, and the side wall 212 being positioned around the electrode assembly 10.

[0160] In some embodiments, the end wall 211 and the side wall 212 may have the same polarity.

[0161] In some embodiments, the end wall 211 and the side wall 212 may be integrally formed, that is, the case 21 may be a single molded part. Of course, the end wall 211 and the side wall 212 may be two separate parts that are connected by methods such as welding, riveting, or bonding.

[0162] From its external appearance, the electrode assembly 10 includes a main body 12, a first tab 111, and a second tab 112. The first tab 111 and the second tab 112 are of opposite polarity, and both protrude from the main body 12. The first tab 111 is the portion of the first electrode plate whose active material layer is not coated, and the second tab 112 is the portion of the second electrode plate whose active material layer is not coated. The first tab 111 and the second tab 112 are used to draw current from the main body 12. The first electrode plate and the second electrode plate are of opposite polarity; in other words, one of the first electrode plate and the second electrode plate is the positive electrode plate, and the other of the first electrode plate and the second electrode plate is the negative electrode plate.

[0163] Let us explain using the example that the first tab 111 is the negative electrode tab and the second tab 112 is the positive electrode tab. On the negative electrode plate, the portion of the negative electrode current collector that is not covered with an active material layer is the negative electrode tab, and the active material that is covered by the negative electrode current collector on the negative electrode plate constitutes the negative electrode film layer. The negative electrode film layer and the portion of the negative electrode current collector that is covered with active material are part of the main body 12. On the positive electrode plate, the portion of the positive electrode current collector that is not covered with an active material layer is the positive electrode tab, and the active material that is covered by the positive electrode current collector on the positive electrode plate constitutes the positive electrode film layer. The positive electrode film layer and the portion of the positive electrode current collector that is covered with active material are part of the main body 12.

[0164] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead section and a second electrode lead section, the first electrode lead section being electrically connected to a first tab 111 and the second electrode lead section being electrically connected to a second tab 112.

[0165] In the axial direction of the main body 12, the first electrode lead-out portion and the second electrode lead-out portion may be located on opposite sides of the electrode assembly 10, or they may be located on the same side of the electrode assembly 10. For example, the second electrode lead-out portion includes an electrode terminal 30 that is insulated from the end wall 211, and the first electrode lead-out portion is the end wall 211.

[0166] The first tab 111 and the second tab 112 may extend from the same side of the main body 12, or they may extend from opposite sides.

[0167] The first tab 111 and the second tab 112 may each be provided on both sides along the axial direction of the main body 12; in other words, the first tab 111 and the second tab 112 may each be provided on both ends along the axial direction of the electrode assembly 10.

[0168] Selectively, the first tab 111 is wound in multiple layers around the central axis of the electrode assembly 10, and the first tab 111 includes multiple tab layers. After winding is complete, the first tab 111 is substantially cylindrical, with gaps remaining between two adjacent tab layers. Embodiments of the present application may treat the first tab 111 to reduce the gaps between the tab layers and facilitate connection between the first tab 111 and other conductive structures. For example, embodiments of the present application may planarize the first tab 111 so that the end of the first tab 111 away from the body 12 is tapered and converges, the planarization forming a dense end face at the end of the first tab 111 away from the body 12, reducing the gaps between the tab layers and facilitating connection between the first tab 111 and other conductive structures. Alternatively, embodiments of the present application may fill the space between two adjacent tab layers with conductive material to reduce the gaps between the tab layers.

[0169] Selectively, the second tab 112 is wound in multiple layers around the central axis of the electrode assembly 10, and the second tab 112 includes multiple tab layers. Exemplarily, the second tab 112 is also planarized to reduce the gaps between the tab layers of the second tab 112.

[0170] The first tab 111 is electrically connected to the end cap 22. The first tab 111 may be electrically connected directly to the end cap 22, or it may be electrically connected indirectly to the end cap 22 via another conductive structure, and the end cap 22 and the end wall 211 are electrically connected.

[0171] The second tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulated from the end wall 211. The second tab 112 may be electrically connected directly to the electrode terminal 30, or it may be electrically connected indirectly to the electrode terminal 30 via another conductive structure.

[0172] In some embodiments, the second tab 112 may be directly connected to the electrode terminal 30, or it may be connected to the electrode terminal 30 by welding, contact, or other means. Alternatively, the second tab 112 may be indirectly connected to the electrode terminal 30 via another conductive member (e.g., a current collector 40) to achieve an electrical connection between the second tab 112 and the electrode terminal 30.

[0173] Since the electrode terminal 30 is installed insulated from the end wall 211, the electrode terminal 30 and the end wall 211 may have different polarities, and the electrode terminal 30 and the end wall 211 may be different output poles.

[0174] The end wall 211 may have electrode lead-out holes, and the electrode terminals 30 are insulated from the end wall 211 and attached to the electrode lead-out holes, which facilitate the extraction of electrical energy from the electrode assembly 10 to the outside of the case 21.

[0175] The central axis of the electrode assembly 10 is a virtual straight line, and the central axis of the electrode assembly 10 may pass through the electrode exit hole or may be offset from the electrode exit hole, but is not limited in this application.

[0176] The electrode terminal 30 may be fixed to the end wall 211. The electrode terminal 30 as a whole may be fixed to the outside of the end wall 211, or it may protrude into the interior of the metal housing 20 through the electrode lead-out hole.

[0177] When the first tab 111 is the negative electrode tab and the second tab 112 is the positive electrode tab, the end wall 211 is the negative output electrode of the cylindrical battery cell 7, but the electrode terminal 30 is the positive output electrode of the cylindrical battery cell 7. When the first tab 111 is the positive electrode tab and the second tab 112 is the negative electrode tab, the end wall 211 is the positive output electrode of the cylindrical battery cell 7, but the electrode terminal 30 is the negative output electrode of the cylindrical battery cell 7.

[0178] In some embodiments, the cylindrical battery cell 7 comprises a metal housing and an electrolyte, the electrolyte being housed within the metal housing, the electrolyte containing an electrolyte salt, the electrolyte containing a hexafluorophosphate and a sulfonylimide salt, and the molar concentration of the hexafluorophosphate being 0.9 mol / L or less.

[0179] Hexafluorophosphate may contain one or more of the following: lithium hexafluorophosphate, sodium hexafluorophosphate, etc. Sulfonylimide salt may contain one or more of the following: lithium sulfonylimide, sodium sulfonylimide, etc.

[0180] Hexafluorophosphates have relatively good solubility and relatively high conductivity in organic solvents, resulting in relatively good kinetic performance for battery cells. Furthermore, hexafluorophosphates form an excellent solid electrolyte interface (SEI) film on the surface of the negative electrode film layer, providing excellent protection to the negative electrode film layer.

[0181] By using a combination of hexafluorophosphate and sulfonylimide salt, the thermal stability of the electrolyte system is relatively increased, and the molar concentration of hexafluorophosphate is relatively low, thereby reducing the corrosive capacity to the metal housing 20. This reduces the risk of corrosion of the metal housing 20, as well as the risk of metal corrosion in the metal housing 20 and the generation of metal ions. Furthermore, by effectively distributing the forces acting within the system, the metal housing 20 of the cylindrical battery cell 7 is subjected to uniform forces, making it less prone to deformation. This is advantageous in improving the reliability and cycle performance of the cylindrical battery cell 7.

[0182] In some embodiments, the molar concentration of hexafluorophosphate is 0.2 mol / L to 0.8 mol / L, and selectively 0.3 mol / L to 0.7 mol / L. When the molar concentration of hexafluorophosphate is within the above range, the corrosive effect on the metal housing 20 can be further reduced, and the reliability and cycle performance of the cylindrical battery cell 7 can be improved.

[0183] For example, the molar concentration of hexafluorophosphate may be in the range of 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, or any two of the above values.

[0184] In some embodiments, the electrolyte salt further contains a sulfonylimide salt, and the ratio of the molar concentration of the sulfonylimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, selectively 0.2 to 2, and even more selectively 0.3 to 1.5. When the ratio of the molar concentration of the sulfonylimide salt to the molar concentration of the hexafluorophosphate salt is within the above range, the thermal stability of the electrolyte salt is relatively good, acid corrosion due to thermal decomposition is less likely to occur, and the electrochemical stability of the electrolyte salt is also relatively good, further enhancing the stability of the electrolyte salt and improving the reliability of the battery cell and its cycle performance.

[0185] For example, the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is within the range of 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8, 5, 5.2, 5.5, 5.8, 6, or any two of the above values.

[0186] In some embodiments, the molar concentration of the electrolyte salt is 0.5 mol / L to 2 mol / L, and selectively, it is 0.6 mol / L to 1.5 mol / L. When the molar concentration of the electrolyte salt is within the above range, it is advantageous to further enhance the stability of the electrolyte salt, thereby improving the reliability and cycle performance of the battery cell, and to improve the dynamic performance of the battery cell by enhancing the liquid phase transport capacity of active ions.

[0187] For example, the molar concentration of the electrolyte salt may be in the range of 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2 mol / L, or any two of the above values.

[0188] In some embodiments, the metal housing 20 includes a housing body and a film layer, the film layer being installed on at least the surface of the housing body facing the electrolyte, and the matrix element of the film layer is nickel. In each embodiment of this application, the matrix element is the element that makes up the largest proportion in the film layer.

[0189] The matrix element of the film layer is nickel, which significantly enhances the acid corrosion resistance of the film layer. If the cylindrical battery cell 7 also contains hexafluorophosphate, the nickel element effectively increases the acid corrosion resistance of the film layer and reduces the risk of metal corrosion in the metal housing 20 and the generation of metal ions, thereby improving the reliability and cycle performance of the cylindrical battery cell 7.

[0190] In some embodiments, the film layer thickness is 1.5 μm to 6.0 μm, and selectively 2.0 μm to 4.0 μm. When the film layer thickness is within the above range, it is advantageous to improve the reliability and cycle performance of the cylindrical battery cell 7 by increasing the corrosion resistance of the film layer.

[0191] For example, the thickness of the film layer may be in the range of 1.5 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, or any two of the above values.

[0192] In some examples, when the molar concentration of hexafluorophosphate is 0.2 mol / L to 0.8 mol / L, the film layer thickness is 1.5 μm to 6.0 μm. By combining the molar concentration of hexafluorophosphate with the film layer thickness, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0193] In some examples, when the molar concentration of hexafluorophosphate is 0.3 mol / L to 0.7 mol / L, the film layer thickness is 2.0 μm to 4.0 μm. By combining the molar concentration of hexafluorophosphate with the film layer thickness, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0194] In some embodiments, the mass content of nickel in the film layer is 70 wt% to 100 wt%, and selectively 80 wt% to 95 wt%. When the mass content of nickel is within the above range, the corrosion resistance of the film layer can be enhanced, thereby improving the reliability and cycle performance of the cylindrical battery cell 7.

[0195] For example, the mass content of the nickel element in the film layer may be in the range of 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 80 wt%, 82 wt%, 85 wt%, 88 wt%, 90 wt%, 92 wt%, 95 wt%, 98 wt%, 99 wt%, 100 wt%, or any two of the above values.

[0196] In some examples, when the molar concentration of hexafluorophosphate is 0.2 mol / L to 0.8 mol / L, the mass content of nickel in the film layer is 70 wt% to 100 wt%. By combining the molar concentration of hexafluorophosphate with the mass content of nickel in the film layer, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0197] In some examples, when the molar concentration of hexafluorophosphate is 0.3 mol / L to 0.7 mol / L, the mass content of nickel in the film layer is 80 wt% to 95 wt%. By combining the molar concentration of hexafluorophosphate with the mass content of nickel in the film layer, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0198] Nickel can exist in the film layer in the form of elemental nickel or nickel alloys, and nickel alloys may be alloys composed of nickel as the matrix element and iron, carbon, and other elements as auxiliary elements.

[0199] In some embodiments, the film layer further contains iron elements, and the mass content of iron elements in the film layer is 0.1 wt% to 10 wt%, selectively 1 wt% to 5 wt%. When the mass content of iron elements is within the above range, the conductivity of the metal housing 20 can be effectively improved, which is advantageous for electron transport.

[0200] For example, the mass content of iron in the film layer may be within the range of 0.1wt%, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 10wt%, or any two of the above values.

[0201] In some embodiments, the film layer further contains carbon, and the mass content of carbon in the film layer is 0.1 wt% to 15 wt%, selectively 4 wt% to 12 wt%. When the mass content of carbon is within the above range, the conductivity of the housing can be effectively improved, which is advantageous for electron transport.

[0202] For example, the mass content of the carbon element in the film layer may be within the range of 0.1wt%, 0.5wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, or any two of the above values.

[0203] In some examples, when the molar concentration ratio of sulfonylimid salt to hexafluorophosphate is 0.06 to 6, the film layer thickness is 1.5 μm to 6.0 μm. By combining the electrolyte salt and the film layer thickness, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0204] In some examples, when the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is 0.2 to 2, the thickness of the film layer is 2.0 μm to 4.0 μm. By combining the electrolyte salt and the thickness of the film layer, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0205] In some embodiments, when the molar concentration ratio of sulfonylimide salt to hexafluorophosphate salt is 0.06 to 6, the mass content of nickel element is 70 wt% to 100 wt%. By combining the electrolyte salt and the mass content of nickel element, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0206] In some embodiments, when the molar concentration ratio of sulfonylimid salt to hexafluorophosphate is 0.2 to 2, the mass content of nickel is 80 wt% to 95 wt%. By combining the electrolyte salt and the mass content of nickel, it is possible to achieve both improved reliability and cycle performance of the cylindrical battery cell 7.

[0207] In some examples, when the ratio of the molar concentration of sulfonylimide salt to the molar concentration of hexafluorophosphate is 0.3 to 1.5, the layered transition metal oxide has the chemical formula Li a Ni b Co c M d O e A f The compound comprises at least one of the compound and its modified compound, wherein 0.3 ≤ b < 1, selectively 0.5 ≤ b < 1, and further selectively 0.75 ≤ b ≤ 0.98. A relatively high mass content of nickel results in relatively active interfacial performance between the layered transition metal oxide and the electrolyte. However, if the ratio of the molar concentration of the sulfonylimide salt to the molar concentration of the hexafluorophosphate is within the above range, the sulfonylimide salt can improve the interfacial stability between the layered transition metal oxide and the electrolyte, reduce the risk caused by side reactions, and improve the cycle performance of the cylindrical battery cell 7.

[0208] For example, b may be a range consisting of 0.3, 0.4, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.88, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, or any two of the above values.

[0209] In some embodiments, the sulfonylimide salt comprises the anion represented by formula A, [ka] In formula A, R1 and R2 each independently contain a halogen atom or a C1-C6 haloalkyl group.

[0210] The sulfonylimide salt of the above material exhibits relatively good thermal stability, which reduces corrosion of the metal housing 20 by the electrolyte salt and is advantageous in improving the reliability and cycle performance of the cylindrical battery cell 7.

[0211] In some embodiments, the halogen atom includes a fluorine atom.

[0212] In some examples, the C1-C6 haloalkyl group includes a C1-C6 fluoroalkyl group.

[0213] In some embodiments, R1 and R2 each independently contain a fluorine atom or a C1-C3 fluoroalkyl group. The above materials are advantageous in that they readily dissociate active ions, have relatively low viscosity of the electrolyte salt, enhance the liquid phase transport capacity of the electrolyte, and improve the kinetic performance of the electrolyte.

[0214] For example, the anion represented by formula A includes one or more of the anions represented by formula A-1 to formula A-5. [ka]

[0215] Selectively, the anion represented by formula A includes one or more of the anions represented by formula A-1 to formula A-2. [ka]

[0216] The film layer can provide protection to the housing body, and the material of the housing body may vary. For example, the matrix material of the housing body may include, but is not limited to, copper, iron, aluminum, steel, or aluminum alloy. Selectively, the matrix material of the housing body may include steel, such as stainless steel, which has relatively excellent mechanical strength, is less prone to deformation, and can further improve the reliability of the cylindrical battery cell 7. In each embodiment of this application, the matrix material is the material that makes up the largest proportion, and of course, the housing body may be made of steel.

[0217] The metal housing 20 includes a case 21 and an end cap 22. The case 21 may include a housing body, in which case the case 21 includes a housing body and a film layer. The end cap 22 may also include a housing body, in which case the end cap 22 includes a housing body and a film layer. Both the case 21 and the end cap 22 include a housing body.

[0218] In some embodiments, the electrolyte contains a linear ester solvent, and the mass content of the linear ester solvent in the electrolyte is 25.5 wt% or more.

[0219] In some embodiments, the cylindrical battery cell 7 includes a metal housing 20, an electrode assembly 10, and an electrolyte, where the metal housing 20 houses the electrode assembly 10 and the electrolyte, and the metal housing 20 has a cylindrical structure, and the electrolyte contains a linear ester solvent, with the mass content of the linear ester solvent in the electrolyte being 25.5 wt% or more.

[0220] The mass content of the linear ester solvent is 25.5 wt% or more, which relatively increases the conductivity of the electrolyte, enhances the liquid phase transport capacity of active ions, and improves the rapid charging and discharging capabilities of the cylindrical battery cell 7, thereby improving the multiplier performance of the cylindrical battery cell 7. However, such solvents may face the problem of decomposition and gas generation during the cycle charging and discharging process of the cylindrical battery cell 7. The metal housing 20 of the cylindrical battery cell 7 adopts a cylindrical structure, which uniformly distributes the pressure inside the cylindrical battery cell 7 and equalizes the force received by each part of the metal housing 20. This effectively increases the pressure resistance capacity of the metal housing 20, thereby improving the reliability of the cylindrical battery cell 7. On the other hand, the electrode assembly 10 undergoes electrolyte extrusion and reflux during the cycle charge-discharge process. However, because the metal housing 20 employs a cylindrical structure, its size along the axial direction of the cylindrical battery cell 7 is much larger than its radial size. This results in a relatively long reflux path for the electrolyte in the axial direction, potentially making it difficult for the electrolyte to sufficiently permeate the electrode assembly 10. In the embodiment of this application, however, a linear ester solvent is employed, and the mass content of the linear ester solvent is 25.5 wt% or more. This results in a relatively low viscosity of the electrolyte system, allowing it to flow easily and permeate the electrode assembly 10, thereby improving the rapid charge and discharge capabilities of the cylindrical battery cell 7, and further improving the magnification performance of the cylindrical battery cell 7. As a result, the embodiment of this application makes it possible to improve both the magnification performance and reliability of the cylindrical battery cell 7 by using a specific electrolyte system in combination with the cylindrical metal housing 20.

[0221] In some examples, the mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%, selectively 25.5 wt% to 70 wt%, and even more selectively 42.5 wt% to 70 wt%. When the mass content of the linear ester solvent is within the above range, the magnification performance and reliability of the battery cell 7 can be further improved, and the cycle performance of the battery cell 7 can also be further improved.

[0222] For example, the mass content of a linear ester solvent in the electrolyte is within the range of 25.5 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, 42 wt%, 45 wt%, 48 wt%, 50 wt%, 52 wt%, 55 wt%, 58 wt%, 60 wt%, 62 wt%, 65 wt%, 68 wt%, 70 wt%, 72 wt%, 75 wt%, 76.5 wt%, or any two of the above values.

[0223] In some embodiments, the linear ester solvent includes linear carbonates. The linear carbonates can improve the conductivity of the electrolyte, enhance the liquid phase transport dynamics of the electrolyte, and further improve the magnification performance and operational reliability of the cylindrical battery cell 7.

[0224] In some embodiments, the mass content of linear carbonate in the electrolyte is 4 wt% to 70 wt%, selectively 4 wt% to 42.5 wt%, and selectively 8.5 wt% to 35 wt%. When the mass content of linear carbonate is within the above range, the conductivity of the electrolyte is improved, the liquid phase transport dynamics performance of the electrolyte is enhanced, the multiplication performance and reliability of use of the battery cell 7 can be further improved, and the cycle performance of the battery cell 7 can also be further improved.

[0225] For example, the mass content of linear carbonates in the electrolyte is within the range of 4 wt%, 4.5 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, or any two of the above values.

[0226] In some examples, the linear carbonate comprises the compound represented by formula I, [ka] In equation I, R11 and R 12 Each of these independently contains a C1-C3 alkyl group or a C1-C3 haloalkyl group. When the chain carbonate is made of the above material, the magnification performance and reliability of the cylindrical battery cell 7 can be further improved, and the cycle performance of the cylindrical battery cell 7 can also be further improved.

[0227] In some embodiments, R 11 and R 12 Each of these independently contains a C1-C3 alkyl group or a C1-C3 fluoroalkyl group.

[0228] For example, a linear carbonate includes one or more of the compounds represented by formulas I-1 to I-6. [ka]

[0229] Selectively, the linear carbonates include the compounds represented by formula I-1. [ka]

[0230] For example, the linear carbonate contains the compound represented by formula I-1, and the mass content of the compound represented by formula I-1 in the electrolyte is 4 wt% to 42.5 wt%, and selectively 8.5 wt% to 35 wt%.

[0231] In some embodiments, the linear ester solvent further comprises linear carboxylic acid esters. By using a combination of linear carboxylic acid esters and linear carbonates, the conductivity of the electrolyte can be improved, the liquid-phase transport dynamics of the electrolyte can be enhanced, and the magnification performance and reliability of the cylindrical battery cell 7 can be further improved, as can the cycle performance of the cylindrical battery cell 7. Of course, linear carboxylic acid esters may also be used alone as a solvent system.

[0232] In some embodiments, the mass content of the chain carboxylic acid ester in the electrolyte is 4 wt% to 70 wt%, optionally 8.5 wt% to 60 wt%, and optionally 20 wt% to 55 wt%. When the mass content of the chain carboxylic acid ester in the electrolyte is within the above range, the conductivity of the electrolyte can be improved, the liquid-phase transport kinetics performance of the electrolyte can be enhanced, and the rate performance and service reliability of the battery cell 7 can be further improved.

[0233] Exemplarily, the mass content of the chain carboxylic acid ester in the electrolyte is 4 wt%, 4.5 wt%, 5 wt%, 8 wt%, 8.5 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt% or a range consisting of any two of the above numerical values.

[0234] In some embodiments, the chain carboxylic acid ester contains a compound represented by Formula II,

Chemical formula

[0235] In some embodiments, R 21 includes a hydrogen atom, a fluorine atom, a C1-C3 alkyl group or a C1-C3 fluoroalkyl group.

[0236] In some embodiments, R 22 includes a C1-C3 alkyl group or a C1-C3 fluoroalkyl group.

[0237] Exemplarily, the chain carboxylic acid ester contains one or more of the compounds represented by Formula II-1 to Formula II-6. [ka]

[0238] Selectively and exemplary, the chain carboxylic acid esters include one or more of the compounds represented by formula II-1 to formula II-6. [ka]

[0239] The linear carboxylic acid ester may include various selective formulations. For example, the chain-like carboxylic acid ester includes the compound shown in formula II-2, and the mass content of the compound shown in formula II-2 in the electrolyte is 20 wt% to 55 wt%.

[0240] Furthermore, for example, the chain-like carboxylic acid ester includes the compound shown in formula II-3, and the mass content of the compound shown in formula II-3 in the electrolyte is 20 wt% to 55 wt%.

[0241] Furthermore, for example, the chain-like carboxylic acid ester includes the compound represented by formula II-2 and the compound represented by formula II-3, and the mass content of the compound represented by formula II-2 and the compound represented by formula II-3 in the electrolyte is 20 wt% to 55 wt%.

[0242] For example, the linear ester solvent of the electrolyte may contain the compound represented by formula I-1 and the compound represented by formula II-2, and the mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%, selectively 25.5 wt% to 70 wt%, and selectively 42.5 wt% to 70 wt%, for example, the mass content of the compound represented by formula I-1 in the electrolyte is 8.5 wt% to 35 wt%, and the mass content of the compound represented by formula II-2 is 20 wt% to 55 wt%.

[0243] For example, the linear ester solvent of the electrolyte may contain the compound represented by formula I-1 and the compound represented by formula II-3, and the mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%, selectively 25.5 wt% to 70 wt%, and selectively 42.5 wt% to 70 wt%, for example, the mass content of the compound represented by formula I-1 in the electrolyte is 8.5 wt% to 35 wt%, and the mass content of the compound represented by formula II-3 in the electrolyte is 20 wt% to 55 wt%.

[0244] For example, the linear ester solvent of the electrolyte may include the compound represented by formula I-1, the compound represented by formula II-2, and the compound represented by formula II-3. The mass content of the linear ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%, selectively 25.5 wt% to 70 wt%, and selectively 42.5 wt% to 70 wt%. For example, the mass content of the compound represented by formula I-1 in the electrolyte is 8.5 wt% to 35 wt%, the mass content of the compound represented by formula II-2 in the electrolyte is 8.5 wt% to 35 wt%, and the mass content of the compound represented by formula II-3 in the electrolyte is 8.5 wt% to 35 wt%.

[0245] The metal housing 20 has a cylindrical structure and includes a case 21, which may also have a cylindrical structure, and the corresponding electrode assembly 10 also has a cylindrical structure. The material of the metal housing 20 may vary; for example, the matrix material of the metal housing 20 may include, but is not limited to, copper, iron, aluminum, steel, aluminum alloy, etc. Selectively, the matrix material of the metal housing 20 may include steel, such as stainless steel. Exemplarily, the matrix material of the case 21 may include steel, such as stainless steel. The shape of the end cap 22 may be adapted to the shape of the case 21 to match the case 21. The matrix material of the end cap 22 may be the same as or different from the matrix material of the case 21. Selectively, the end cap 22 may be made of a material having a certain hardness and strength (for example, copper, iron, aluminum, steel, aluminum alloy, plastic, etc.), so that the end cap 22 is less likely to deform when subjected to extrusion and impact, the cylindrical battery cell 7 can be given higher structural strength, and reliability can be improved. Selectively, the matrix material of the end cap 22 may include steel, for example, stainless steel. In each embodiment of this application, the matrix material is the material that constitutes the largest proportion.

[0246] In some embodiments, the metal housing 20 includes a case 21 and an end cap 22, the case 21 includes a side wall 212 and an end wall 211 connected to the side wall 212, the case 21 has an opening, the end cap 22 is connected to the side wall 212 and covers the opening, and the end cap 22 and the end wall 211 face each other along the axial direction of the metal housing 20.

[0247] In some embodiments, the side wall 212 and the end wall 211 are integrally formed structures.

[0248] In some embodiments, the matrix material of the sidewall 212 includes steel, and the thickness of the sidewall 212 is 0.30 mm to 1.2 mm, selectively 0.30 mm to 0.55 mm. When the thickness of the sidewall 212 is within the above range, the strength of the sidewall 212 is relatively high, it has a stronger pressure resistance capacity, effectively mitigates the risk of deformation of the sidewall 212, and reduces the risk of expansion of the cylindrical battery cell 7, thereby improving the reliability of use of the cylindrical battery cell 7.

[0249] For example, the thickness of the side wall 212 may be within the range of 0.30 mm, 0.31 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.45 mm, 0.48 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.5 mm, or any two of the above values.

[0250] In some embodiments, the matrix material of the side wall 212 includes steel, and when the thickness of the side wall 212 is 0.30 mm to 1.2 mm, the mass content of the linear ester solvent is 25.5 wt% to 76.5 wt%. When the mass content of the linear ester solvent is within the above range, the magnification performance of the cylindrical battery cell 7 can be increased, but there is a risk of expansion of the cylindrical battery cell 7 due to the generation of a certain amount of gas inside the cylindrical battery cell 7. On the other hand, when the thickness of the metal housing 20 in the embodiments of this application is within the above range, the strength of the metal housing 20 is relatively high, and it has a stronger pressure resistance capacity, effectively mitigating the risk of deformation of the metal housing 20 and reducing the risk of expansion of the cylindrical battery cell 7, thereby increasing the reliability of use of the cylindrical battery cell 7 and improving the cycle performance of the cylindrical battery cell 7.

[0251] In some embodiments, the matrix material of the side wall 212 includes steel, the thickness of the side wall 212 is 0.30 mm to 0.55 mm, and the mass content of the chain ester solvent is 25.5 wt% to 70 wt%. By combining the thickness of the metal housing 20 and the mass content of the chain ester solvent as described above, it is possible to achieve both an improvement in the rate performance and the usage reliability of the cylindrical battery cell 7, and to improve the cycle performance of the cylindrical battery cell 7.

[0252] FIG. 6 is a schematic cross-sectional view of the cylindrical battery cell 7 according to some embodiments of the present application, and FIG. 7 is an enlarged schematic view at A of the cylindrical battery cell 7 shown in FIG. 6.

[0253] As shown in FIGS. 6 and 7, in some embodiments, the metal housing 20 includes a case 21 and an end cap 22. The case 21 has an opening, and the end cap 22 is connected to the case 21 and covers the opening. A pressure relief mechanism 220 is provided on the end cap 22.

[0254] When phenomena such as a short circuit or overcharging occur, the electrolyte reacts with the active material to release gas and heat. The pressure relief mechanism 220 is configured to deform when the internal pressure or temperature of the metal housing 20 reaches a threshold value, and to communicate the internal space of the metal housing 20 with the external space, thereby releasing the pressure or temperature inside the metal housing 20. The deformation of the pressure relief mechanism 220 includes, but is not limited to, rupture, melting, etc. This threshold design varies depending on the design requirements. The threshold value may depend on one or more materials among the positive electrode plate, the negative electrode plate, the electrolyte, and the separator member in the cylindrical battery cell 7.

[0255] In the embodiments of the present application, the deformation of the pressure relief mechanism 220 may be triggered by the internal pressure of the metal housing 20, may be triggered by the internal temperature of the metal housing 20, or may be triggered by a combination of the internal pressure and the internal temperature of the metal housing 20.

[0256] For example, as gas constantly accumulates inside the metal housing 20, the internal pressure of the metal housing 20 can reach and eventually exceed a pressure threshold. When the internal pressure of the metal housing 20 reaches the threshold, the pressure relief mechanism 220 deforms due to the action of the internal pressure, connecting the internal space and the external space of the metal housing 20, and releasing the gas inside the metal housing 20, thereby reducing the risk of the cylindrical battery cell 7 exploding.

[0257] For example, when the electrolyte and active material react and rapidly release heat, the internal temperature of the metal housing 20 rises, and the internal pressure of the metal housing 20 also rises due to the temperature increase. When the internal temperature of the metal housing 20 reaches a threshold, the pressure release mechanism 220 deforms under the action of temperature and pressure, allowing the internal space and external space of the metal housing 20 to communicate, thereby releasing the gas inside the metal housing 20 and reducing the risk of the cylindrical battery cell 7 exploding.

[0258] When the internal pressure or temperature of the metal housing 20 reaches a threshold, the embodiment of this application utilizes the deformation of the pressure release mechanism 220 to connect the internal and external spaces of the metal housing 20, and further releases the internal gas and internal pressure of the metal housing 20, thereby reducing the risk of the cylindrical battery cell 7 rupturing.

[0259] In some embodiments, the end cap 22 is provided with a recess 221, the bottom wall of which is a weak point 222. The weak point 222 is configured to rupture when the internal pressure of the cylindrical battery cell 7 reaches a threshold, thereby releasing the internal pressure.

[0260] After the vulnerable portion 222 ruptures, a channel is formed that can be used to release internal pressure. After the vulnerable portion 222 ruptures, the internal gas of the cylindrical battery cell 7 is released to the outside from the ruptured area, and by generating pressure relief in the cylindrical battery cell 7 in this manner, where the pressure can be controlled, the occurrence of a potential and more serious accident can be avoided.

[0261] In some embodiments, the matrix material of the weak portion 222 includes steel, and the thickness of the weak portion 222 is 0.01 mm to 0.3 mm, selectively 0.05 mm to 0.2 mm. When the thickness of the weak portion 222 is within the above range, the strength of the weak portion 222 is relatively high, and it has a stronger pressure resistance capacity, which can effectively increase the pressure resistance capacity of the cylindrical battery cell 7 and improve the reliability of the cylindrical battery cell 7.

[0262] For example, the thickness of the weak portion 222 may be within the range of 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.07 mm, 0.08 mm, 0.09 mm, 0.1 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, 0.2 mm, or any two of the above values.

[0263] In some embodiments, the matrix material of the weak portion 222 includes steel, and when the thickness of the weak portion 222 is 0.01 mm to 0.3 mm, the mass content of the linear ester solvent is 25.5 wt% to 76.5 wt%. When the mass content of the linear ester solvent is within the above range, the magnification performance of the cylindrical battery cell 7 can be increased, but there is a risk of expansion of the cylindrical battery cell 7 due to the generation of a certain amount of gas inside the cylindrical battery cell 7. However, when the thickness of the weak portion 222 in the embodiments of this application is within the above range, the strength of the weak portion 222 is relatively high, and it has a stronger pressure resistance capacity, which can effectively increase the pressure resistance capacity of the cylindrical battery cell 7 and improve the reliability of the cylindrical battery cell 7 in use.

[0264] In some embodiments, the matrix material of the weak portion 222 includes steel, the thickness of the weak portion 222 is 0.05 mm to 0.2 mm, and the mass content of the linear ester solvent is 25.5 wt% to 70 wt%. By combining the thickness of the metal housing 20 and the mass content of the linear ester solvent as described above, it is possible to achieve both improved magnification performance and reliability of use for the cylindrical battery cell 7.

[0265] In some examples, the organic solvent may further include, but is not limited to, a cyclic carbonate and at least one of butylene carbonate (BC), fluoroethylene carbonate (FEC), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE). Selectively, the organic solvent further includes a cyclic carbonate. Exemplarily, the cyclic carbonate includes at least one of ethylene carbonate (EC), propylene carbonate (PC), and fluoroethylene carbonate (FEC).

[0266] The qualitative and quantitative determination of each substance or element in the electrolyte in this application can be performed using appropriate instruments and methods known to those skilled in the art. Relevant detection methods can be determined by referring to domestic and international detection standards, domestic and international company standards, etc. Furthermore, those skilled in the art can adaptively change several detection steps / instrument parameters from the viewpoint of detection accuracy to obtain more accurate detection results. Qualitative or quantitative measurements may be performed using a single detection method, or multiple detection methods may be used in combination for qualitative or quantitative measurements.

[0267] In the embodiments of this application, the types and content of inorganic components / lithium salts in the electrolyte are known in the art and can be detected using instruments and methods known in the art. For example, referring to standard JY / T020-1996 "General Rules for Ion Chromatography Analysis," the inorganic components / lithium salt concentrations in the electrolyte can be analyzed qualitatively or quantitatively by ion chromatography analysis. In the embodiments of this application, a newly manufactured electrolyte can be used as a sample, or a battery that has already been discharged (discharged to the lower cutoff voltage so that the battery's charge state is approximately 0% SOC) can be reverse-disassembled, and the free electrolyte obtained from the battery can be used as a sample for detection using ion chromatography analysis.

[0268] In the embodiments of this application, the types and content of organic components in the electrolyte are as known in the art and can be detected using instruments and methods known in the art. For example, the organic components in the electrolyte can be qualitatively or quantitatively analyzed by gas chromatography, referring to GB / T9722-2006 "General Rules for Gas Chromatography of Chemical Reagents." In the embodiments of this application, a newly manufactured electrolyte can be used as a sample, or a battery that has already been discharged (discharged to the lower cutoff voltage so that the battery's charge state is approximately 0% SOC) can be reverse-disassembled, and the free-released electrolyte obtained from the battery can be used as a sample for detection using ion chromatography analysis.

[0269] In the embodiments of this application, the thickness of the weak portion 222 is as known in the art and can be detected using instruments and methods known in the art, for example, by testing the thickness using a micrometer.

[0270] In the embodiments of this application, the thickness of the film layer is as known in the art and can be detected using instruments and methods known in the art, for example, by cutting the housing 20, testing the thickness of the film layer at different locations using an X-ray thickness gauge, and taking the average value as the thickness of the film layer.

[0271] In the embodiments of this application, the types and content of elements in the film layer are as known in the art and can be detected using instruments and methods known in the art. For example, an energy spectrometer and an electron scanning microscope can be used to detect the proportion of the types and content of elements on the surface of the film layer. The proportion of the types and content of elements on the surface of the film layer is essentially the same as the types and content of elements in the film layer, and the types and content of elements in the film layer are characterized by detecting the proportion of the types and content of elements on the surface of the film layer. [Examples]

[0272] The following examples provide a more detailed description of the examples disclosed in this application, and are used for descriptive purposes only, as it will be apparent to those skilled in the art that various modifications and changes can be made within the scope of the examples disclosed in this application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or can be synthesized according to conventional methods and can be used directly without further processing, and all instruments used in the examples are commercially available.

[0273] Example 1 1. Manufacturing of positive electrode plates The positive electrode plate comprises a positive electrode current collector and a positive electrode film layer. The positive electrode film layer is located on both sides of the positive electrode current collector. The positive electrode current collector is aluminum foil. The positive electrode film layer is formed by uniformly coating the surface of the aluminum foil positive electrode current collector with a positive electrode slurry (solvent: N-methylpyrrolidone NMP), followed by drying and cold pressing. The positive electrode film layer contains a positive electrode active material in a weight ratio of 96.5:2:1.5, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive.

[0274] The positive electrode active material has the molecular formula LiNi 0.9 Co 0.05 Mn 0.05 It contains O2(Ni90) compounds.

[0275] 2. Manufacturing of the negative electrode plate The negative electrode plate includes a negative electrode current collector and a negative electrode film layer. The negative electrode film layer is located on both sides of the negative electrode current collector. The negative electrode current collector is copper foil. The negative electrode film layer is formed by uniformly coating the surface of the copper foil of the negative electrode current collector with a negative electrode slurry (solvent is deionized water), followed by drying and cold pressing. The negative electrode film layer contains a negative electrode active material in a weight ratio of 96.2:1.8:1.2:0.8, styrene-butadiene rubber (SBR) as an adhesive, sodium carboxymethylcellulose (CMC-Na) as a thickener, and acetylene black as a conductive agent.

[0276] The negative electrode active material contains artificial graphite and silicon-based materials (specifically, silicon-carbon compounds), and the silicon element content in the negative electrode film layer is 5%.

[0277] 3. Separator The separator is a polypropylene (PP) film layer.

[0278] 4. Manufacturing of electrolyte The electrolyte contains an organic solvent and a lithium salt. The organic solvent includes a linear ester solvent and a cyclic ester solvent (ethylene carbonate). The linear ester solvent contains a linear carbonate (dimethyl carbonate DMC) and a linear carboxylic acid ester (methyl acetate and ethyl acetate in a mass ratio of 1:1). The mass ratio of the linear carbonate, linear carboxylic acid ester, and ethylene carbonate is 3:4:3. The lithium salt contains lithium hexafluorophosphate LiPF6 and lithium bis(fluorosulfonyl)imide LiFSI. Dimethyl carbonate DMC, methyl acetate, ethyl acetate, and ethylene carbonate are mixed in the above mass ratios, and then the thoroughly dried lithium salt is dissolved in the mixed organic solvent to prepare the electrolyte. The molar concentration of lithium hexafluorophosphate LiPF6 is 0.6 mol / L, and the molar concentration of lithium bis(fluorosulfonyl)imide LiFSI is 0.4 mol / L.

[0279] 5. Manufacturing of cylindrical battery cells The positive electrode plate, separator, and negative electrode plate are stacked in order, with the separator positioned between the positive and negative electrode plates to provide isolation. The positive electrode plate, separator, and negative electrode plate are wound together to obtain an electrode assembly. The electrode assembly is placed in a cylindrical housing. After drying, an electrolyte is injected, and a cylindrical battery cell is obtained through processes such as vacuum packaging, settling, chemical formation, and shaping. Here, the housing includes a case and an end cap. The case includes integrally formed side walls and end walls. The side walls are positioned around the electrode assembly. The end cap and end walls face each other along the axial direction of the housing. The side walls include a housing body and a film layer. The film layer is located on two surfaces of the housing body. The housing body is made of stainless steel. The film layer has a thickness of 3 μm and contains 90 wt% nickel, 2 wt% iron, and 5 wt% carbon.

[0280] Comparative Example 1 A cylindrical battery cell was manufactured using a method similar to that of Example 1, the difference being that the lithium salt contained 1.0 mol / L lithium hexafluorophosphate LiPF6 and the sidewall did not contain a film layer.

[0281] Examples 2-1 to 2-10 A cylindrical battery cell was manufactured using a method similar to that of Example 1, the only difference being the adjustment of the lithium salt composition. Here, the housing in Examples 2-1 to 2-9 includes a housing body and a film layer, while the side wall in Example 2-10 does not include a film layer.

[0282] Examples 3-1 and 3-2 A cylindrical battery cell was manufactured using a method similar to that of Example 1, the only difference being that the type of sulfonylimide salt used in the lithium salt was adjusted.

[0283] Performance testing 1. Battery cell cycle performance test At 45°C, the cylindrical battery cells produced in each example and comparative example were charged with a constant current at a multiplier of 0.5C until the charge cutoff voltage reached 4.25V. Then, they were charged with a constant voltage until the current was 0.05C or less, left to stand for 5 minutes, and then discharged with a constant current at a multiplier of 0.33C until the discharge cutoff voltage reached 2.5V, left to stand for 5 minutes. This constituted one charge-discharge cycle. A cycle charge-discharge test was performed on the battery cells according to the above procedure, and the capacity retention rate of the battery cells after 800 cycles was calculated.

[0284] 2. Battery storage gas generation test At 25°C, the cylindrical battery cells produced in each example and comparative example were charged with a constant current at a multiplier of 0.5C up to 4.25V, then charged with a constant voltage until the current was ≤0.05C, and the batteries were stored at 60°C for 100 days. The internal pressure (MPa) of the batteries was then detected using an external pressure gauge.

[0285] 3. Internal resistance test of battery cells At 25°C, the cylindrical battery cells produced in each example and comparative example were charged with a constant current at a multiplier of 1C up to 4.25V, then charged with a constant voltage until the current was 0.05C or less, and finally discharged at 1C for 30 minutes to adjust the battery cell capacity to a state of charge (SOC) of 50%.

[0286] The positive and negative probes of the TH2523A AC internal resistance tester were used to contact the positive and negative terminals of the battery cell, respectively, and the internal resistance value (mΩ) of the battery cell was read using the internal resistance tester.

[0287] Test results The test results are shown in Table 1.

[0288] [Table 1]

[0289] In Table 1, Formula A-1 represents the bisfluorosulfonylimide ion, and the corresponding cation is the lithium ion. Equation A-2 represents the bistrifluoromethanesulfonylimide ion, and the corresponding cation is the lithium ion. Equation A-3 represents the (fluorosulfonyl)(trifluoromethanesulfonyl)imide ion, and the corresponding cation is the lithium ion.

[0290] As can be seen from Table 1, In Comparative Example 1, the molar concentration of lithium hexafluorophosphate was relatively high, making it prone to causing corrosion in the housing. Compared to Comparative Example 1, the embodiment of this application reduces the molar concentration of lithium hexafluorophosphate, thereby effectively reducing the amount of hydrofluoric acid generated by the decomposition of lithium hexafluorophosphate, which can mitigate corrosion to the housing. This is advantageous for improving the cycle performance of the cylindrical battery cell, and can also reduce the internal pressure of the cylindrical battery cell, decrease gas generation, and improve the reliability of the cylindrical battery cell during use.

[0291] Examples 2-1 to 2-10 demonstrate that by adjusting the composition of the lithium salt, the cycle performance of the cylindrical battery cell can be further enhanced, the internal pressure of the cylindrical battery cell can be reduced, the amount of gas generated can be decreased, the reliability of the cylindrical battery cell can be improved, the ion liquid phase transport capacity of the electrolyte system can be improved, resistance can be reduced, and the magnification performance can be enhanced. Examples 3-1 and 3-2 demonstrate that by adjusting the composition of the sulfonylimide salt, the cycle performance of the cylindrical battery cell can be further enhanced, the internal pressure of the cylindrical battery cell can be reduced, the amount of gas generated can be decreased, the reliability of the cylindrical battery cell can be improved, the ion liquid phase transport capacity of the electrolyte system can be improved, resistance can be reduced, and the magnification performance can be enhanced.

[0292] Example 4 A cylindrical battery cell was manufactured using a method similar to that of Example 1, the only difference being that the thickness of the film layer on the side wall of the housing was adjusted.

[0293] Example 5 A cylindrical battery cell was manufactured using a method similar to that of Example 1, the only difference being that the composition of the film layer on the side wall of the housing was adjusted.

[0294] The test results are shown in Table 2.

[0295] [Table 2]

[0296] As can be seen from Table 2, the electrolyte system in the embodiments of this application is applied to metal housings with different film thicknesses, for example, 1.5 μm to 6.0 μm, and selectively 2.0 μm to 4.0 μm. When the film layer satisfies the above range, the battery has excellent cycle performance and reliability.

[0297] The electrolyte system in the embodiment of this application is applied to a metal housing with a film layer having a different nickel content, for example, 70 wt% to 100 wt%, and selectively 80 wt% to 95 wt%, and when the mass content of the elemental nickel satisfies the above range, the battery has excellent cycle performance and reliability in use.

[0298] While explanatory embodiments have already been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on this application, and that modifications, substitutions, and alterations may be made to the embodiments without departing from the spirit, principles, and scope of this application.

[0299] Although explanatory embodiments have already been shown and described, those skilled in the art should understand that the above embodiments should not be construed as limitations on this application, and that modifications, substitutions, and alterations can be made to the embodiments without departing from the spirit, principles, and scope of this application. [Explanation of Symbols]

[0300] The explanation of the symbols is as follows: X, axial direction; Y, radial direction; 1. Vehicle, 2. Battery, 3. Controller, 4. Motor, 5. Housing, 5a. First housing section, 5b. Second housing section, 5c. Enclosure space, 6. Battery module, 7. Cylindrical battery cell, 10. Electrode assembly, 111. First tab, 112. Second tab, 12. Main body, 20, metal housing, 21, case, 211, end wall, 212, side wall, 22, end cap, 220, pressure release mechanism, 221, recess, 222, weak point, 30, electrode terminal; 40. Current collection components.

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