Cylindrical battery cell, battery and electric device

Abstract

A cylindrical battery cell, a battery and an electric device. The cylindrical battery cell comprises an electrolyte, an electrode assembly and a casing, wherein the casing houses the electrolyte and the electrode assembly. The electrolyte comprises an electrolyte salt, and the electrolyte salt comprises hexafluorophosphate. The casing comprises a casing body and a film layer, the film layer is at least arranged on the surface of the casing body facing the electrode assembly, and the matrix element of the film layer is a nickel element. The operational reliability and cycle performance of the cylindrical battery cell in the embodiments can be improved.

Description

Cylindrical battery cell, battery and electric device

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 202410543473.X, filed on April 30, 2024, entitled “Cylindrical battery cell, battery and electric device”, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of rechargeable batteries, and in particular to a cylindrical battery cell, a battery and an electric device. BACKGROUND

[0004] Battery cells have characteristics such as high capacity, and are therefore widely used in electronic devices such as mobile phones, notebook computers, electric vehicles, electric cars, electric planes, electric ships, electric toy cars, electric toy ships, electric toy planes, and electric tools, etc.

[0005] With the development of the field of battery cells, the requirements for battery performance are gradually increasing, and the use reliability and cycle performance of battery cells need to be further improved. SUMMARY

[0006] The present application provides a cylindrical battery cell, a battery and an electric device, and the use reliability and cycle performance of the cylindrical battery cell in the embodiments of the present application can be improved.

[0007] In a first aspect, the embodiments of the present application provide a cylindrical battery cell, which comprises an electrolyte, an electrode assembly and a shell, the shell containing the electrolyte and the electrode assembly, wherein the electrolyte comprises an electrolyte salt, and the electrolyte salt comprises a hexafluorophosphate salt; the shell comprises a shell body and a film layer, the film layer being arranged on at least the surface of the shell body facing the electrode assembly, and the base element of the film layer being a nickel element.

[0008] Thus, in the embodiments of the present application, the base element of the film layer is a nickel element, which significantly improves the acid corrosion resistance of the film layer; when the cylindrical battery cell further comprises a hexafluorophosphate salt, the nickel element can also effectively improve the acid corrosion resistance of the film layer, reduce the risk of metal corrosion to generate metal ions in the shell, and the shell of the cylindrical battery cell can effectively disperse the acting force in the system, so that the shell is uniformly stressed and is not prone to deformation, thereby facilitating the improvement of the use reliability and cycle performance of the cylindrical battery cell, etc. In the embodiments of the present application, the base element refers to the element with the largest proportion in the film layer.

[0009] In some embodiments, the molar concentration of the hexafluorophosphate salt is less than or equal to 1.2 mol / L. The molar concentration of the hexafluorophosphate salt in the above range can further reduce the corrosion effect on the shell, improve the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0010] In some embodiments, the molar concentration of the hexafluorophosphate salt is less than or equal to 0.9 mol / L. The molar concentration of the hexafluorophosphate salt in the above range can further reduce the corrosion effect on the shell, improve the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0011] In some embodiments, the molar concentration of the hexafluorophosphate salt is 0.2 mol / L to 0.8 mol / L. The molar concentration of the hexafluorophosphate salt in the above range can further improve the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0012] In some embodiments, the molar concentration of the hexafluorophosphate salt is 0.3 mol / L to 0.7 mol / L. The molar concentration of the hexafluorophosphate salt in the above range can further improve the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0013] In some embodiments, the thickness of the film layer is 1.5 μm to 6.0 μm. When the thickness of the film layer is in the above range, it is beneficial to increase the corrosion resistance of the film layer, thereby improving the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0014] In some embodiments, the thickness of the film layer is 2.0 μm to 4.0 μm. When the thickness of the film layer is in the above range, it is beneficial to increase the corrosion resistance of the film layer, thereby improving the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0015] In some embodiments, the mass percentage content of the nickel element in the film layer is 70 wt% to 100 wt%. When the mass percentage content of the nickel element is in the above range, the corrosion resistance of the film layer is improved, thereby improving the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0016] In some embodiments, the mass percentage content of the nickel element in the film layer is 80 wt% to 95 wt%. When the mass percentage content of the nickel element is in the above range, the corrosion resistance of the film layer is improved, thereby improving the use reliability and cycle performance of the cylindrical battery monomer, and the like.

[0017] In some embodiments, the film layer further comprises an iron element, and the mass percentage content of the iron element in the film layer is 0.1 wt% to 10 wt%, which can be optionally 1 wt% to 5 wt%. When the mass percentage content of the iron element is in the above range, the conductivity of the shell can be effectively improved, which is beneficial to electron transmission.

[0018] In some embodiments, the film layer further comprises carbon elements, and the mass percentage of the carbon elements in the film layer is 0.1 wt% to 15 wt%, or 4 wt% to 12 wt%. When the mass percentage of the carbon elements is within the above range, the conductivity of the shell can be effectively improved, and the electron transmission is facilitated.

[0019] In some embodiments, the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6. When the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is within the above range, the thermal stability of the electrolyte salt is relatively excellent, and thermal decomposition to cause acid corrosion is less likely to occur; and the electrochemical stability of the electrolyte salt is relatively excellent, which can further improve the stability of the electrolyte salt, the use reliability and cycle performance of the battery cell, and the like.

[0020] In some embodiments, the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2. When the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is within the above range, the stability of the electrolyte salt can be further improved, and the use reliability and cycle performance of the battery cell, and the like can be improved.

[0021] In some embodiments, the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.3 to 1.5. When the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is within the above range, the stability of the electrolyte salt can be further improved, and the use reliability and cycle performance of the battery cell, and the like can be improved.

[0022] In some embodiments, the molar concentration of the electrolyte salt is 0.5 mol / L to 2 mol / L. When the molar concentration of the electrolyte salt is within the above range, the stability of the electrolyte salt can be further improved, the use reliability and cycle performance of the battery cell, and the like can be improved; and the liquid-phase transmission capacity of the active ion can be improved, so that the kinetic performance of the battery cell is improved.

[0023] In some embodiments, the molar concentration of the electrolyte salt is 0.6 mol / L to 1.5 mol / L. When the molar concentration of the electrolyte salt is within the above range, the kinetic performance of the battery cell can be further improved.

[0024] In some embodiments, the sulfimide salt comprises an anion represented by Formula A,

[0025] In Formula A, R1 and R2 each independently comprise a halogen atom or a C1 to C6 halogenated alkyl group.

[0026] Therefore, the sulfimide salt of the above material in the embodiments of the present application has relatively excellent thermal stability, which is conducive to reducing the corrosion of the electrolyte salt to the shell, improving the use reliability and cycle performance of the battery cell, and the like.

[0027] In some embodiments, the halogen atom comprises a fluorine atom.

[0028] In some embodiments, the C1 to C6 haloalkyl group comprises a C1 to C6 fluoroalkyl group.

[0029] In some embodiments, R1 and R2 each independently comprise a fluorine atom or a C1 to C3 fluoroalkyl group.

[0030] In some embodiments, the anion of Formula A comprises one or more of an anion of Formula A-1 to an anion of Formula A-5,

[0031] In some embodiments, the anion of Formula A comprises one or more of an anion of Formula A-1 to an anion of Formula A-2,

[0032] In some embodiments, the base material of the shell body is steel. The shell body with the above material has excellent mechanical strength and is not easy to deform, which can further improve the use reliability of the cylindrical battery cell.

[0033] In some embodiments, the electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprises a negative electrode current collector and a negative electrode film layer containing a negative electrode active material arranged on at least one side of the negative electrode current collector, and the negative electrode active material comprises silicon elements. When the mass content of silicon elements is in the above range, the energy density of the cylindrical battery cell can be improved; and the cylindrical shell can constrain the expanded electrode assembly, so that the force of the electrode assembly on the shell is evenly distributed, the shell is not easy to deform, the structural stability of the shell is improved, and the use reliability of the cylindrical battery cell is improved.

[0034] In some embodiments, the mass percentage content of silicon elements in the negative electrode film layer is 1% to 32%. When the mass content of silicon elements is in the above range, the energy density of the cylindrical battery cell can be improved; and the use reliability of the cylindrical battery cell can be improved.

[0035] In some embodiments, the electrolyte comprises a chain ester solvent, and the mass percentage content of the chain ester solvent in the electrolyte is greater than or equal to 25.5wt%.

[0036] Therefore, in the embodiments of the present application, the mass percentage content of the chain ester solvent is greater than or equal to 25.5wt%, so that the conductivity of the electrolyte is relatively high, which is beneficial to improve the liquid phase transmission capacity of active ions and the rapid charging and discharging capacity of the battery cell, thereby improving the rate performance of the battery cell.

[0037] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%. When the mass percentage content of the chain ester solvent is in the above range, the rate performance and use reliability of the battery cell can be further improved, and the cycle performance of the battery cell can be further improved.

[0038] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 25.5wt% to 70wt%. When the mass percentage content of the chain ester solvent is in the above range, the rate performance and use reliability of the battery cell can be further improved, and the cycle performance of the battery cell can be further improved.

[0039] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 42.5wt% to 70wt%. When the mass percentage content of the chain ester solvent is in the above range, the rate performance and use reliability of the battery cell can be further improved, and the cycle performance of the battery cell can be further improved.

[0040] In some embodiments, the chain ester solvent includes a chain carbonate, and the mass percentage content of the chain carbonate in the electrolyte is 4wt% to 70wt%. When the mass percentage content of the chain carbonate is in the above range, the electrical conductivity of the electrolyte can be improved, the liquid-phase transport kinetics performance of the electrolyte can be improved, and the rate performance and use reliability of the battery cell can be further improved.

[0041] In some embodiments, the mass percentage content of the chain carbonate in the electrolyte is 4wt% to 42.5wt%. When the mass percentage content of the chain carbonate is in the above range, the electrical conductivity of the electrolyte can be improved, the liquid-phase transport kinetics performance of the electrolyte can be improved, and the rate performance and use reliability of the battery cell can be further improved.

[0042] In some embodiments, the chain carbonate includes a compound shown in Formula I,

[0043] In Formula I, R 11 and R 12 Each independently includes a C1 to C3 alkyl or a C1 to C3 haloalkyl.

[0044] Therefore, when the chain carbonate in the embodiments of the present application is the above material, the rate performance and use reliability of the battery cell can be further improved.

[0045] In some embodiments, R 11 and R 12 Each independently includes a C1 to C3 alkyl or a C1 to C3 haloalkyl.

[0046] In some embodiments, the chain carbonate includes one or more of a compound shown in Formula I-1 to a compound shown in Formula I-6,

[0047] In some embodiments, the chain carbonate includes a compound shown in Formula I-1,

[0048] In some embodiments, the chain carbonate includes a compound shown in Formula I-1,

[0049] In some embodiments, the mass percentage of the chain carbonate in the electrolyte is 4wt% to 70wt%. The chain carbonate and the chain carboxylic acid ester are used in combination, which can improve the conductivity of the electrolyte, improve the liquid-phase transport kinetics of the electrolyte, and further improve the rate performance and use reliability of the battery cell.

[0050] In some embodiments, the chain carboxylic acid ester includes a compound shown in Formula II,

[0051] In Formula II,

[0052] R 21 including a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group;

[0053] R 22 including a C1 to C3 alkyl group or a C1 to C3 haloalkyl group.

[0054] Therefore, the chain carboxylic acid ester and the chain carbonate of the above-mentioned material used in combination in the embodiments of the present application can further improve the rate performance and use reliability of the battery cell.

[0055] In some embodiments, R 21 including a hydrogen atom, a fluorine atom, a C1 to C3 alkyl group, or a C1 to C3 fluoroalkyl group.

[0056] In some embodiments, R 22 including a C1 to C3 alkyl group or a C1 to C3 fluoroalkyl group.

[0057] In some embodiments, the chain carboxylic acid ester includes one or more of a compound shown in Formula II-1 to a compound shown in Formula II-6,

[0058] In some embodiments, the chain carboxylic acid ester includes one or more of a compound shown in Formula II-2 and a compound shown in Formula II-3.

[0059] In some embodiments, the chain carbonate includes a compound shown in Formula I-1,

[0060] The mass percentage of the compound shown in Formula I-1 in the electrolyte is 8.5wt% to 35wt%;

[0061] The chain carboxylic acid ester includes a compound shown in Formula II-2 and a compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0062] In some embodiments, the shell includes a shell body and an end cover, the shell body includes a side wall and an end wall connected to the side wall, the shell body has an opening, the end cover is connected to the side wall and covers the opening, and the end cover and the end wall are opposite along the axial direction of the cylindrical battery cell.

[0063] In some embodiments, the base material of the side wall is steel, and the thickness of the side wall is 0.30mm to 1.2mm. When the thickness of the side wall is in the above range, the strength of the side wall is higher, and the side wall has stronger pressure bearing capacity, which can effectively reduce the risk of deformation of the side wall and the risk of swelling of the battery cell, thereby improving the use reliability of the battery cell.

[0064] In some embodiments, the thickness of the side wall is 0.30mm to 0.55mm. When the thickness of the side wall is in the above range, the risk of swelling of the battery cell can be reduced, thereby improving the use reliability of the battery cell.

[0065] In some embodiments, the side wall and the end wall are formed in an integrated structure.

[0066] In some embodiments, the end cover is provided with a pressure relief mechanism. The pressure relief mechanism is deformed under the action of internal pressure to communicate the internal space of the shell with the external space, and the gas in the shell can be discharged, thereby reducing the risk of explosion of the battery cell.

[0067] In some embodiments, the pressure relief mechanism includes a weak part, the base material of the weak part includes steel, and the thickness of the weak part is 0.01mm to 0.3mm. When the thickness of the weak part is in the above range, the strength of the weak part is higher, and the weak part has stronger pressure bearing capacity, which can effectively improve the pressure resistance of the battery cell and improve the use reliability of the battery cell.

[0068] In some embodiments, the thickness of the weak part is 0.05mm to 0.2mm. When the thickness of the weak part is in the above range, the use reliability of the battery cell can be further improved.

[0069] In some embodiments, the end cover is provided with a recess, and the bottom wall of the recess is the weak part. This kind of structure is simple and convenient to process.

[0070] In some embodiments, the battery cell further includes an electrode terminal disposed at the end wall; the battery cell includes an electrode assembly accommodated in the housing, the electrode assembly including first and second tabs of opposite polarity, the first tab being electrically connected to the end wall, and the second tab being electrically connected to the electrode terminal.

[0071] In some embodiments, the housing has an axial dimension along itself that is 1.3 to 2.5 times a radial dimension of the housing along the cylindrical battery cell.

[0072] In some embodiments, the housing has an axial dimension along the cylindrical battery cell that is 50 to 150 mm.

[0073] In some embodiments, the housing has a radial dimension along the cylindrical battery cell that is 40 to 80 mm.

[0074] In a second aspect, the embodiments of the present application further provide a battery, which includes the cylindrical battery cell according to any of the embodiments of the first aspect of the present application.

[0075] In a third aspect, the embodiments of the present application further provide an electric device, which includes the battery according to any of the embodiments of the second aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0076] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments of the present application. Obviously, the drawings described below are only some of the embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0077] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application;

[0078] FIG. 2 is an exploded schematic diagram of a battery according to some embodiments of the present application;

[0079] FIG. 3 is an exploded schematic diagram of a battery module according to some embodiments of the present application;

[0080] FIG. 4 is a structural schematic diagram of a cylindrical battery cell according to some embodiments of the present application;

[0081] FIG. 5 is an exploded schematic diagram of a cylindrical battery cell according to some embodiments of the present application;

[0082] FIG. 6 is a sectional schematic diagram of a cylindrical battery cell according to some embodiments of the present application;

[0083] FIG. 7 is an enlarged schematic diagram of the cylindrical battery cell at position A shown in FIG. 6.

[0084] The drawings are not necessarily drawn to scale.

[0085] Reference signs are explained as follows:

[0086] X, axial direction; Y, radial direction;

[0087] 1, vehicle; 2, battery; 3, controller; 4, motor; 5, case; 5a, first case portion; 5b, second case portion; 5c, accommodation space; 6, battery module; 7, cylindrical battery cell;

[0088] 10, electrode assembly; 111, first tab; 112, second tab; 12, main body portion;

[0089] 20, housing; 21, case; 211, end wall; 212, side wall;

[0090] 22, end cap; 220, pressure relief mechanism; 221, recess; 222, weak portion;

[0091] 30, electrode terminal;

[0092] 40, current collecting member. DETAILED DESCRIPTION

[0093] Hereinafter, specific embodiments of the cylindrical battery cell, the battery, and the electric device of the present application are concretely explained with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed explanations are omitted. For example, there are cases where detailed explanations of matters well known, repeated explanations of actually identical structures are omitted. This is to avoid the following explanation from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following explanation are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0094] "RANGES" disclosed herein are defined by a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, the selected lower limit and upper limit defining the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" indicates a shorthand way of describing each and every number that is an integer within the given range of a and b, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand way of describing those numerical combinations. Additionally, when a parameter is stated to be an integer > 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0095] Unless otherwise indicated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0096] Unless otherwise indicated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0097] Unless otherwise indicated, all steps of the present application can be performed in sequence or randomly, and preferably in sequence. For example, a method comprising steps (a) and (b) indicates that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, it is mentioned that the method can further comprise step (c), indicating that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0098] In the present application, the phrase "embodiment" means that the specific features, structures or properties described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor is it independent or alternative to other embodiments.

[0099] In the description of the application, it should be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "attachment" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0100] In the present application, the term "and / or" is only a description of the association relationship between the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects have an "or" relationship.

[0101] In the embodiments of the present application, the same reference signs represent the same components, and for the sake of brevity, the detailed description of the same components is omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device, are only exemplary and should not constitute any limitation on the present application.

[0102] "Multiple" appearing in the present application means two or more (including two). In the embodiments of the present application, the battery cell can be a secondary battery, which refers to a battery cell that can be activated by charging after discharging the battery cell.

[0103] The battery cell can include, but is not limited to, a lithium ion battery cell, a sodium ion battery cell, a sodium lithium ion battery cell, a lithium metal battery cell, a sodium metal battery cell, a lithium sulfur battery cell, a magnesium ion battery cell, a nickel hydrogen battery cell, a nickel cadmium battery cell, a lead-acid battery cell, etc.

[0104] As an example, the battery cell can be a cylindrical battery cell, which refers to a battery cell whose outer shape is in a cylindrical structure or similar to a cylindrical structure.

[0105] The battery referred to in the embodiments of the present application refers to a single physical module including one or more battery cells to provide higher voltage and capacity.

[0106] In some embodiments, the battery can be a battery module, and when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module.

[0107] In some embodiments, the battery can be a battery pack, and the battery pack includes a box body and a battery cell, and the battery cell or the battery module is contained in the box body.

[0108] In some embodiments, the box can be part of a chassis structure of the vehicle. For example, parts of the box can be part of a floor of the vehicle, or parts of the box can be part of crossbeams and longitudinal beams of the vehicle.

[0109] In some embodiments, the battery can be an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0110] The battery cell includes an electrolyte and a shell. The electrolyte includes an electrolyte salt such as hexafluorophosphate, which has poor thermal stability and is prone to decomposition to produce hydrofluoric acid (HF). HF can corrode the shell, especially a metal shell, which can pose a risk to the reliability of the cylindrical battery cell. Moreover, metal ions generated by the corrosion of the metal shell can also exist in the electrolyte, which can adversely affect the battery cell, such as deteriorating the cycle performance and storage performance of the battery cell.

[0111] In view of this, the embodiments of the present application provide a cylindrical battery cell. The shell of the cylindrical battery cell includes a shell body and a film layer. The base element of the film layer is nickel, which significantly improves the acid corrosion resistance of the film layer. When the cylindrical battery cell also includes hexafluorophosphate, the nickel element can also effectively improve the acid corrosion resistance of the film layer and reduce the risk of metal ions generated by the corrosion of the metal in the shell, thereby improving the reliability and cycle performance of the cylindrical battery cell.

[0112] The cylindrical battery cell described in the embodiments of the present application is suitable for use in batteries and power consuming devices using batteries.

[0113] The cylindrical battery cell, the battery and the power consuming device disclosed in the embodiments of the present application can be used in power consuming devices using batteries as power sources or various energy storage systems using batteries as energy storage elements. The power consuming device can be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, an electric vehicle, an electric car, a ship, a spacecraft, etc. The electric toy can include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric plane toys, etc. The spacecraft can include airplanes, rockets, space shuttles and spacecraft, etc.

[0114] The following embodiments are described for convenience with the power consuming device being a vehicle as an example.

[0115] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application.

[0116] As shown in FIG. 1, the vehicle 1 is internally provided with a battery 2, which can be arranged at the bottom, head or tail of the vehicle 1. The battery 2 can be used for power supply of the vehicle 1, for example, the battery 2 can be used as an operating power source of the vehicle 1.

[0117] The vehicle 1 can further comprise a controller 3 and a motor 4, the controller 3 being configured to control the battery 2 to supply power to the motor 4, for example, for the power requirements of the vehicle 1 during start-up, navigation and driving.

[0118] In some embodiments of the present application, the battery 2 can not only serve as a power source for the operation of the vehicle 1, but also serve as a driving power source for the vehicle 1, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1.

[0119] FIG. 2 is an exploded view of the battery according to some embodiments of the present application. As shown in FIG. 2, the battery 2 comprises a box 5 and a cylindrical battery cell (not shown in FIG. 2), the cylindrical battery cell being accommodated in the box 5.

[0120] The box 5 is configured to accommodate the cylindrical battery cell, and the box 5 can have various structures. In some embodiments, the box 5 can comprise a first box part 5a and a second box part 5b, the first box part 5a and the second box part 5b being coupled to each other, and the first box part 5a and the second box part 5b together defining an accommodation space 5c for accommodating the cylindrical battery cell. The second box part 5b can be a hollow structure with one open end, and the first box part 5a can be a plate-like structure, the first box part 5a being coupled to the open end of the second box part 5b to form the box 5 with the accommodation space 5c. Alternatively, the first box part 5a and the second box part 5b can both be hollow structures with one open end, the open end of the first box part 5a being coupled to the open end of the second box part 5b to form the box 5 with the accommodation space 5c. Of course, the first box part 5a and the second box part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0121] To improve the sealing performance of the first box part 5a and the second box part 5b after being coupled, a sealing member, such as a sealing glue, a sealing ring, etc., can be provided between the first box part 5a and the second box part 5b.

[0122] Suppose the first box part 5a is coupled to the top of the second box part 5b, the first box part 5a can also be referred to as an upper box cover, and the second box part 5b can also be referred to as a lower box.

[0123] In the battery 2, the cylindrical battery cell can be one or multiple. If the cylindrical battery cell is multiple, the multiple cylindrical battery cells can be connected in series, in parallel or in a mixed manner. The mixed manner means that the multiple cylindrical battery cells are connected in both series and parallel. The multiple cylindrical battery cells can be directly connected in series, in parallel or in a mixed manner, and then the whole of the multiple cylindrical battery cells is accommodated in the box 5. Alternatively, the multiple cylindrical battery cells can be first connected in series, in parallel or in a mixed manner to form a battery module 6, and then the multiple battery modules 6 are connected in series, in parallel or in a mixed manner to form a whole, which is accommodated in the box 5.

[0124] The cylindrical battery cell can be the smallest unit of the battery.

[0125] FIG. 3 is a structural schematic diagram of the battery module shown in FIG. 2.

[0126] In some embodiments, as shown in FIG. 3, the plurality of cylindrical battery cells 7 are connected in series or in parallel or in a mixed manner to form a battery module 6. The plurality of battery modules 6 are connected in series or in parallel or in a mixed manner to form a whole and are accommodated in a box.

[0127] The plurality of cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize parallel connection, series connection or mixed connection of the plurality of cylindrical battery cells 7 in the battery module. The busbar component can be one or more, and each busbar component is used to electrically connect at least two cylindrical battery cells.

[0128] FIG. 4 is a structural schematic diagram of a cylindrical battery cell provided in some embodiments of the present application; and FIG. 5 is an exploded schematic diagram of the cylindrical battery cell shown in FIG. 4.

[0129] As shown in FIGS. 4 and 5, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a shell 20, and the electrode assembly 10 is accommodated in the shell 20.

[0130] The shell 20 is a cylindrical structure, and the shell 20 includes a shell body 21 which is a cylindrical structure. The shape of the electrode assembly 10 is also a cylindrical structure.

[0131] In some embodiments, the dimension of the shell 20 along the axial direction X of the cylindrical battery cell 7 is 1.3 to 2.5 times, 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 a range composed of any two of the above values, of the dimension of the shell 20 along the radial direction Y of the cylindrical battery cell 7. When the shell 20 satisfies the above size requirement, the volume expansion of the electrode assembly 10 can be effectively constrained, the extrusion force on the shell 20 is more evenly distributed, the shell 20 is less likely to deform, and the use reliability of the cylindrical battery cell 7 can be improved.

[0132] Exemplarily, the dimension of the shell 20 along the axial direction X is 50 to 150 mm, for example, 50 mm, 55 mm, 60 mm, 65 mm, 70 mm, 75 mm, 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm, 120 mm, 125 mm, 130 mm, 135 mm, 140 mm, 145 mm, 150 mm or a range composed of any two of the above values.

[0133] Exemplarily, the shell 20 has a dimension of 40mm to 80mm along the radial direction Y, for example, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, or a range between any two of the above values.

[0134] The electrode assembly 10 includes a positive electrode and a negative electrode. During charging and discharging of the cylindrical battery cell 7, active ions (e.g., lithium ions) are inserted into and extracted from the positive electrode and the negative electrode. Optionally, the electrode assembly 10 further includes a separator disposed between the positive electrode and the negative electrode, which can reduce the risk of short circuit between the positive electrode and the negative electrode, while allowing the active ions to pass through.

[0135] In some embodiments, the positive electrode can be a positive electrode tab, which can include a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0136] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of the positive electrode current collector, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0137] As an example, the positive electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, stainless steel, copper, aluminum, nickel, carbon electrode, carbon, nickel, titanium, silver surface treated aluminum, or stainless steel, etc. can be used. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0138] As an example, when the cylindrical battery cell 7 of the embodiments of the present application is a lithium ion battery, the positive electrode active material can include at least one of the following materials: phosphate, layered transition metal oxide, and their respective modified compounds; optionally, the positive electrode active material can include layered transition metal oxide and their respective modified compounds, which is conducive to improving the energy density of the cylindrical battery cell 7. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode film layers of batteries can also be used. These positive electrode active materials can be used alone or in combination with two or more.

[0139] Examples of phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite material of lithium manganese iron phosphate and carbon.

[0140] Layered transition metal oxides include at least one of compounds of the general formula Li a Ni b Co c M d O e A f and modified compounds thereof. 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.

[0141] Examples of layered transition metal oxides can include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also can be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 ), LiNi 0.9 Co 0.05 Mn 0.05 O2(also can be referred to as Ni90), lithium nickel cobalt aluminum oxide (such as LiNi 0.80 Co 0.15 Al 0.05 O2), and modified compounds thereof, etc.

[0142] When the cylindrical battery cell 7 of the embodiments of the present application is a sodium ion battery, the positive active material can include, but is not limited to, at least one of sodium-containing transition metal oxides, polyanion materials (such as phosphates, fluorophosphates, pyrophosphates, sulfates, etc.), Prussian blue type materials, etc.

[0143] As an example, the positive active material for sodium ion battery can include at least one of NaFe02, NaCo02, NaCr02, NaMn02, NaNi02, 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 type material, material of general formula X p M’ q (PO4) r O x Y 3-x In general formula X p M’ q (PO4) r O x Y 3-x , 0 < p < 4, 0 < q < 2, 1 < r < 3, 0 < x < 2, X includes at least one of H + , Li + , Na + , K + and NH4 + , M’ is a transition metal cation, which can be at least one of V, Ti, Mn, Fe, Co, Ni, Cu and Zn, and Y is a halide anion, which can be at least one of F, Cl and Br.

[0144] In the embodiments of the present application, the modified compounds of the above-mentioned positive active materials can be doping modification and / or surface coating modification, such as carbon coating modification, fast ion conductor coating modification, etc.

[0145] The cylindrical battery cell 7 will be accompanied by the deintercalation and consumption of active ions such as Li during the charging and discharging process, and the molar content of Li is different when the cylindrical battery cell 7 is discharged to different states. In the embodiments of the present application, the enumeration of the positive active material, the molar content of Li is the initial state of the material, that is, the state before feeding, and the positive active material is applied to the battery system, and after charging and discharging cycle, the molar content of Li can change.

[0146] In the embodiments of the present application, the enumeration of the positive active material, the molar content of oxygen O is only the theoretical state value, and the release of oxygen from the lattice will cause the change of the molar content of oxygen O, and in fact, the molar content of oxygen O will appear floating.

[0147] In the embodiments of the present application, the content of elements in the positive electrode active material is in the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, referring to EPA 6010D-2014, tested by inductively coupled plasma atomic emission spectrometry, and determined by plasma atomic emission (ICP-OES, instrument model: Thermo ICAP7400). First, 0.4 g of the positive electrode active material is weighed, and 10 ml (50% concentration) aqua regia is added thereto. Then, it is placed on a 180°C flat plate for 30 min. After digestion on the flat plate, it is diluted to a volume of 100 mL, and a quantitative test is performed by a standard curve method.

[0148] In some embodiments, the positive electrode can use a foamed metal. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. When the foamed metal is used as the positive electrode, the surface of the foamed metal can not be provided with a positive electrode film layer, of course, the positive electrode film layer can also be provided. As an example, the foamed metal can also be filled or / and deposited with a lithium source material, potassium metal or sodium metal, and the lithium source material is lithium metal and / or lithium-rich material.

[0149] In some embodiments, the positive electrode film layer can also optionally include a positive electrode conductive agent. The type of positive electrode conductive agent is not particularly limited in the embodiments of the present application, as an example, the positive electrode conductive agent includes at least one of super-conductive carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, the mass percentage content of the positive electrode conductive agent in the positive electrode film layer is ≤5wt%.

[0150] In some embodiments, the positive electrode film layer can also optionally include a positive electrode binder. The type of positive electrode binder is not particularly limited in the embodiments of the present application, as an example, the positive electrode binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic ester resin. In some embodiments, the mass percentage content of the positive electrode binder in the positive electrode film layer is ≤5wt%.

[0151] The positive electrode film layer is usually formed by coating a positive electrode slurry on a positive electrode current collector, drying and cold pressing. The positive electrode slurry is usually formed by dispersing and uniformly stirring the positive electrode active material, the optional conductive agent, the optional binder and any other components in a solvent. The solvent can be N-methyl pyrrolidone (NMP), but is not limited thereto.

[0152] In some embodiments, the negative electrode can be a negative electrode sheet, which can include a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0153] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is provided on either one or both of the two surfaces of the negative electrode current collector.

[0154] As an example, the negative electrode current collector can adopt a metal foil, a foamed metal, or a composite current collector. For example, as the metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, or the like can be used. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, or the like. The composite current collector can include a polymer material base layer and a metal layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, or the like) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, or the like).

[0155] As an example, the negative electrode active material can adopt a negative electrode active material known in the art for use in the cylindrical battery cell 7. As an example, the negative electrode active material can include at least one of a carbon material (for example, the carbon material includes at least one of artificial graphite, natural graphite, soft carbon, hard carbon), a silicon-based material, a tin-based material, and lithium titanate, or the like. The silicon-based material can include at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The tin-based material can include at least one of elemental tin, a tin oxide compound, and a tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative electrode film layer for a battery can also be used. These negative electrode film layers can be used alone or in combination with two or more.

[0156] In some embodiments, the negative electrode active material includes a silicon element, which can be in the form of a silicon-based material, for example, the silicon-based material can include at least one of elemental silicon, a silicon oxide compound, a silicon-carbon composite, a silicon-nitrogen composite, and a silicon alloy. The introduction of the silicon element can improve the energy density of the cylindrical battery cell 7.

[0157] In some embodiments, the mass content of the silicon element in the negative electrode film layer is 1wt% to 32wt%, optionally 2wt% to 19wt%, and further optionally 6wt% to 13wt%. When the mass content of the silicon element is within the above range in the cylindrical battery cell 7 system, the energy density of the cylindrical battery cell 7 can be improved; and the cylindrical structure of the shell 20 can constrain the expanded electrode assembly 10, so that the force of the electrode assembly 10 on the shell 20 is dispersed more evenly, and the shell 20 is less likely to deform, thereby improving the structural stability of the shell 20 and improving the use reliability of the cylindrical battery cell 7.

[0158] In the embodiments of the present application, the mass content of silicon element in the negative electrode film layer is in the meaning known in the art, which can be detected by using the devices and methods known in the art, for example, the negative electrode sheet is placed in a solvent such as water for soaking, the negative electrode active material is separated from the negative electrode current collector, the negative electrode active material is obtained by suction filtration, and the content of silicon element is obtained by using the inductively coupled plasma-optical emission spectrometer of ICAP7400 model of Thermo Fisher Scientific Company, USA, and referring to the standard GB / T30902-2014.

[0159] In some embodiments, the negative electrode film layer optionally further comprises a negative electrode conductive agent. The embodiments of the present application do not have special restrictions on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent can comprise at least one of super-conductive carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, the mass percentage content of the negative electrode conductive agent in the negative electrode film layer is ≤5wt%.

[0160] In some embodiments, the negative electrode film layer optionally further comprises a negative electrode binder. The embodiments of the present application do not have special restrictions on the type of negative electrode binder. As an example, the negative electrode binder can comprise at least one of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-based acrylic resin (for example, polyacrylic acid PAA, polymethylacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA) and carboxymethyl chitosan (CMCS). In some embodiments, the mass percentage content of the negative electrode binder in the negative electrode film layer is ≤5wt%.

[0161] In some embodiments, the negative electrode film layer optionally further comprises other auxiliary agents. As an example, the other auxiliary agents can comprise thickening agents, for example, carboxymethyl cellulose sodium (CMC-Na), PTC thermistor material, etc. In some embodiments, the mass percentage content of the other auxiliary agents in the negative electrode film layer is ≤2wt%.

[0162] In some embodiments, the material of the positive electrode current collector can be aluminum, and the material of the negative electrode current collector can be copper.

[0163] In some embodiments, the separator comprises a separator film. The embodiments of the present application do not have special restrictions on the type of separator film, and any known porous structure separator film with good chemical stability and mechanical stability can be selected.

[0164] The embodiments of the present application do not have special restrictions on the type of separator film, and any known porous structure separator film with good chemical stability and mechanical stability can be selected.

[0165] In some embodiments, the material of the isolation film can include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The isolation film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the isolation film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0166] In some embodiments, the isolation film can include a porous base film and a coating layer disposed on at least one side of the porous base film, and the coating layer can include at least one of inorganic particles or organic particles.

[0167] The porous base film can include one or more of polyethylene, polypropylene.

[0168] The inorganic particles have good heat resistance and can improve the overall heat resistance of the isolation film. The inorganic particles are substantially not oxidized and reduced with metal dendrites within the operating voltage range of the sodium-ion battery, in other words, the inorganic particles are configured to not be oxidized and reduced with alkali metals and / or alkaline earth metals at the nominal voltage of the sodium-ion battery.

[0169] In some embodiments, the inorganic particles include one or more of 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.

[0170] In some embodiments, the organic particles include at least one of polystyrene, polyethylene, polyimide, melamine resin, phenolic resin, polypropylene, polyester (e.g., polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate), polyphenylene sulfide, polyaramide, polyamide-imide, polyimide, a copolymer of butyl acrylate and ethyl methacrylate, and a mixture thereof.

[0171] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte.

[0172] During the charging and discharging of the battery cell, active ions are embedded and extracted between the positive electrode and the negative electrode, and the electrolyte plays a role in conducting active ions between the positive electrode and the negative electrode. The type of electrolyte is not particularly limited in the embodiments of the present application, and can be selected according to actual needs.

[0173] The electrolyte includes an electrolyte salt and a solvent. The types of electrolyte salt and solvent are not particularly limited, and can be selected according to actual needs.

[0174] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and an additive capable of improving certain performance of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature performance of the battery, an additive capable of improving low-temperature power performance of the battery, and the like.

[0175] For example, the additive includes at least one of a cyclic carbonate compound containing an unsaturated bond, a sulfate compound, a sulfite compound, a sulfonic acid lactone compound, a disulfonic acid compound, a nitrile compound, an aromatic compound, an isocyanate compound, a phosphazene compound, an anhydride, a cyclic anhydride compound, a phosphite compound, a phosphate compound, a borate, a carboxylate compound.

[0176] As shown in FIGS. 4 and 5, in some embodiments, the electrode assembly 10 can be a wound structure or a stacked structure, and optionally, the electrode assembly 10 is a wound structure. The positive electrode sheet and the negative electrode sheet are wound to form the wound structure.

[0177] As an example, a plurality of positive electrode sheets and a plurality of negative electrode sheets can be provided, respectively, and the plurality of positive electrode sheets and the plurality of negative electrode sheets can be alternately stacked.

[0178] In some embodiments, the housing 20 includes a shell 21 having an opening and an end cap 22 for covering the opening.

[0179] The shell 21 is a component for cooperating with the end cap 22 to form an internal cavity of the cylindrical battery cell 7, and the internal cavity can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0180] The shell 21 and the end cap 22 can be independent components. As an example, the shell 21 can be provided with an opening, and the end cap 22 can be used to cover the opening to form the internal cavity of the cylindrical battery cell 7.

[0181] The end cap 22 can be connected to the shell 21 by welding, bonding, clamping, or other means.

[0182] The shell 21 can be open at one end or at both ends. In some examples, the shell 21 can be a structure open at one side, and the end cap 22 can be provided as one and cover the shell 21. In other examples, the shell 21 can also be a structure open at both sides, and the end cap 22 can be provided as two and cover the two openings of the shell 21, respectively.

[0183] In some embodiments, the shell 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 are opposite along the axial direction of the cylindrical battery cell 7, the end cap 22 is sealingly connected to the side wall 212, and the side wall 212 surrounds the electrode assembly 10.

[0184] In some embodiments, the end wall 211 and the side wall 212 can have the same polarity.

[0185] In some embodiments, the end wall 211 and the side wall 212 can be integrally formed structure, i.e. the shell 21 is an integrally formed member. Of course, the end wall 211 and the side wall 212 can also be two members provided separately and then connected together by welding, riveting, bonding or the like.

[0186] From the appearance of the electrode assembly 10, the electrode assembly 10 includes the main body part 12, the first tab 111 and the second tab 112, the polarities of the first tab 111 and the second tab 112 are opposite, and the first tab 111 and the second tab 112 respectively protrude from the main body part 12. The first tab 111 is a portion of the first tab that is not coated with an active material layer, and the second tab 112 is a portion of the second tab that is not coated with an active material layer. The first tab 111 and the second tab 112 are used to lead out the current in the main body part 12. The polarities of the first tab and the second tab are opposite, in other words, one of the first tab and the second tab is a positive electrode tab, and the other of the first tab and the second tab is a negative electrode tab.

[0187] Taking the first tab 111 as a negative electrode tab and the second tab 112 as a positive electrode tab as an example for description; the portion of the negative electrode current collector in the negative electrode tab that is not coated with an active material layer is a negative electrode tab, and the active material coated by the negative electrode current collector in the negative electrode tab constitutes a negative electrode film layer, and the negative electrode film layer and the portion of the negative electrode current collector coated with the active material are part of the main body part 12. The portion of the positive electrode current collector in the positive electrode tab that is not coated with an active material layer is a positive electrode tab, and the active material coated by the positive electrode current collector in the positive electrode tab constitutes a positive electrode film layer, and the positive electrode film layer and the portion of the positive electrode current collector coated with the active material are part of the main body part 12.

[0188] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out part and a second electrode lead-out part, the first electrode lead-out part is electrically connected to the first tab 111, and the second electrode lead-out part is electrically connected to the second tab 112.

[0189] In the axial direction of the main body part 12, the first electrode lead-out part and the second electrode lead-out part can also be located on both sides of the electrode assembly 10, or the first electrode lead-out part and the second electrode lead-out part are located on the same side of the electrode assembly 10, for example, the second electrode lead-out part includes an electrode terminal 30 which is insulated from the end wall 211, and the first electrode lead-out part is the end wall 211.

[0190] The first tab 111 and the second tab 112 can protrude from the same side of the main body part 12, or can respectively extend from opposite sides.

[0191] The first and second tabs 111 and 112 can be respectively arranged on both sides of the body portion 12 along the axial direction, in other words, the first and second tabs 111 and 112 are respectively arranged on both ends of the electrode assembly 10 along the axial direction.

[0192] Optionally, the first tab 111 is wound around the central axis of the electrode assembly 10 into multiple turns, and the first tab 111 includes multiple tab layers. After winding is completed, the first tab 111 is generally cylindrical, and a gap is left between adjacent two tab layers. The first tab 111 can be processed in the embodiments of the present application to reduce the gap between the tab layers and facilitate the connection of the first tab 111 with other conductive structures. For example, the first tab 111 can be subjected to a flattening treatment in the embodiments of the present application, so that the end portion of the first tab 111 away from the body portion 12 is gathered together; the flattening treatment forms a dense end face at the end of the first tab 111 away from the body portion 12, reduces the gap between the tab layers, and facilitates the connection of the first tab 111 with other conductive structures. Alternatively, the embodiments of the present application can also fill conductive material between adjacent two tab layers to reduce the gap between the tab layers.

[0193] Optionally, the second tab 112 is wound around the central axis of the electrode assembly 10 into multiple turns, and the second tab 112 includes multiple tab layers. Exemplarily, the second tab 112 is also subjected to a flattening treatment to reduce the gap between the tab layers of the second tab 112.

[0194] The first tab 111 is electrically connected to the end cover 22. The first tab 111 can be directly electrically connected to the end cover 22, or indirectly electrically connected to the end cover 22 through other conductive structures, and the end cover 22 is electrically connected to the end wall 211.

[0195] The second tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulatively arranged on the end wall 211. The second tab 112 can be directly electrically connected to the electrode terminal 30, or indirectly electrically connected to the electrode terminal 30 through other conductive structures.

[0196] In some embodiments, the second tab 112 can be directly connected to the electrode terminal 30, for example, by welding, abutting or other means. Alternatively, the second tab 112 can also be indirectly connected to the electrode terminal 30 through other conductive components (for example, the current collecting member 40) to achieve the electrical connection of the second tab 112 with the electrode terminal 30.

[0197] The electrode terminal 30 is insulatively arranged on the end wall 211, and therefore, the electrode terminal 30 and the end wall 211 can have different polarities and can serve as different output poles.

[0198] The end wall 211 can be provided with an electrode lead-out hole, and the electrode terminal 30 is insulatedly arranged on the end wall 211 and mounted on the electrode lead-out hole, so as to facilitate leading out the electric energy of the electrode assembly 10 to the outside of the shell 21.

[0199] The central axis of the electrode assembly 10 is a virtual straight line, which can pass through the electrode lead-out hole or be arranged away from the electrode lead-out hole, which is not limited in the present application.

[0200] The electrode terminal 30 can be fixed to the end wall 211. The electrode terminal 30 can be fixed integrally on the outside of the end wall 211, or can extend into the inside of the shell 20 through the electrode lead-out hole.

[0201] When the first tab 111 is a negative electrode tab and the second tab 112 is a positive electrode tab, the end wall 211 is a negative output pole of the cylindrical battery monomer 7, and the electrode terminal 30 is a positive output pole of the cylindrical battery monomer 7. When the first tab 111 is a positive electrode tab and the second tab 112 is a negative electrode tab, the end wall 211 is a positive output pole of the cylindrical battery monomer 7, and the electrode terminal 30 is a negative output pole of the cylindrical battery monomer 7.

[0202] In some embodiments, the cylindrical battery monomer 7 includes a shell 20, an electrode assembly 10 and an electrolyte, the shell 20 contains the electrode assembly 10 and the electrolyte, wherein the electrolyte includes an electrolyte salt, and the electrolyte salt includes a hexafluorophosphate salt; the shell 20 includes a shell body and a film layer, the film layer is arranged at least on the surface of the shell body facing the electrode assembly 10, and the base element of the film layer is a nickel element.

[0203] The hexafluorophosphate salt can include one or more of lithium hexafluorophosphate, sodium hexafluorophosphate, etc. The hexafluorophosphate salt has good solubility and high conductivity in organic solvents, so that the battery monomer has good kinetic performance; and the hexafluorophosphate salt can form an excellent solid electrolyte interface film (SEI film) on the surface of the negative electrode film layer, which has an excellent protective effect on the negative electrode film layer.

[0204] The base element of the film layer is a nickel element, which significantly improves the acid corrosion resistance of the film layer; when the cylindrical battery monomer 7 includes a hexafluorophosphate salt, the nickel element can also effectively improve the acid corrosion resistance of the film layer, reduce the risk of metal corrosion to generate metal ions in the shell 20, and the shell 20 of the cylindrical battery monomer 7 can effectively disperse the force in the system, so that the shell 20 is uniformly stressed and is not easy to deform, thereby facilitating to improve the use reliability and cycle performance of the cylindrical battery monomer 7, etc. In the embodiments of the present application, the base element refers to the element with the largest proportion in the film layer. The nickel element can exist in the form of nickel element or nickel alloy in the film layer, and the nickel alloy can be an alloy with nickel as the base element and iron and carbon as auxiliary elements.

[0205] In some embodiments, the molar concentration of the hexafluorophosphate salt is less than or equal to 1.2 mol / L, optionally less than or equal to 0.9 mol / L, and optionally 0.2 mol / L to 0.8 mol / L, and further optionally 0.3 mol / L to 0.7 mol / L. The molar concentration of the hexafluorophosphate salt in the above range can further reduce the corrosion effect on the shell 20, and improve the use reliability and cycle performance of the cylindrical battery cell 7, and the like.

[0206] Exemplarily, the molar concentration of the hexafluorophosphate salt can be 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, 1.0 mol / L, 1.1 mol / L, 1.15 mol / L, 1.2 mol / L, or a range composed of any two of the above values.

[0207] In some embodiments, the thickness of the film layer is 1.5 μm to 6.0 μm, and optionally 2.0 μm to 4.0 μm. When the thickness of the film layer is in the above range, the corrosion resistance of the film layer is increased, thereby improving the use reliability and cycle performance of the cylindrical battery cell 7, and the like.

[0208] Exemplarily, the thickness of the film layer can be 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 a range composed of any two of the above values.

[0209] In some embodiments, the mass percentage content of the nickel element in the film layer is 70 wt% to 100 wt%, and optionally 80 wt% to 95 wt%. When the mass percentage content of the nickel element is in the above range, the corrosion resistance of the film layer is improved, thereby improving the use reliability and cycle performance of the cylindrical battery cell 7, and the like.

[0210] Exemplarily, the mass percentage content of the nickel element in the film layer can be 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 a range composed of any two of the above values.

[0211] In some embodiments, the film layer further comprises an iron element, and the mass percentage of the iron element in the film layer is 0.1wt% to 10wt%, or 1wt% to 5wt%. When the mass percentage of the iron element is within the above range, the conductivity of the shell 20 can be effectively improved, and the electron transmission is facilitated.

[0212] For example, the mass percentage of the iron element in the film layer can be 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 a range formed by any two of the above values.

[0213] In some embodiments, the film layer further comprises a carbon element, and the mass percentage of the carbon element in the film layer is 0.1wt% to 15wt%, or 4wt% to 12wt%. When the mass percentage of the carbon element is within the above range, the conductivity of the shell 20 can be effectively improved, and the electron transmission is facilitated.

[0214] For example, the mass percentage of the carbon element in the film layer can be 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 a range formed by any two of the above values.

[0215] In some embodiments, the electrolyte salt further comprises a sulfonimide salt, and the sulfonimide salt and the hexafluorophosphate salt are used in combination, so that the thermal stability of the electrolyte system is relatively high, the stability of the electrolyte is improved, and the cycle performance of the cylindrical battery monomer 7 is improved.

[0216] The sulfonimide salt can include one or more of lithium sulfonimide and sodium sulfonimide.

[0217] In some embodiments, the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, optionally 0.2 to 2, and further optionally 0.3 to 1.5. When the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is within the above range, the thermal stability of the electrolyte salt is relatively excellent, and thermal decomposition leading to acid corrosion is less likely to occur. Moreover, the electrochemical stability of the electrolyte salt is relatively excellent, which can further improve the stability of the electrolyte salt, and improve the use reliability and cycle performance of the battery cell, etc.

[0218] For example, the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 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 a range formed by any two of the above values.

[0219] In some embodiments, the molar concentration of the electrolyte salt is 0.5 mol / L to 2 mol / L, and optionally the molar concentration of the electrolyte salt 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 beneficial to further improve the stability of the electrolyte salt, and improve the use reliability and cycle performance of the battery cell, etc. Moreover, it is beneficial to improve the liquid-phase transport capacity of the active ion, thereby improving the kinetic performance of the battery cell.

[0220] For example, the molar concentration of the electrolyte salt can be 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 a range formed by any two of the above values.

[0221] In some embodiments, when the molar concentration of the hexafluorophosphate salt is 0.2 mol / L to 0.8 mol / L, the thickness of the film layer is 1.5 μm to 6.0 μm. The molar concentration of the hexafluorophosphate salt and the thickness of the film layer cooperate to improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0222] In some embodiments, the molar concentration of the hexafluorophosphate salt is 0.3 mol / L to 0.7 mol / L, and the thickness of the film layer is 2.0 μm to 4.0 μm. The molar concentration of the hexafluorophosphate salt and the thickness of the film layer are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0223] In some embodiments, the molar concentration of the hexafluorophosphate salt is 0.2 mol / L to 0.8 mol / L, and the mass percentage of the nickel element in the film layer is 70 wt% to 100 wt%. The molar concentration of the hexafluorophosphate salt and the mass percentage of the nickel element in the film layer are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0224] In some embodiments, the molar concentration of the hexafluorophosphate salt is 0.3 mol / L to 0.7 mol / L, and the mass percentage of the nickel element in the film layer is 80 wt% to 95 wt%. The molar concentration of the hexafluorophosphate salt and the mass percentage of the nickel element in the film layer are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0225] In some embodiments, the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, and the thickness of the film layer is 1.5 μm to 6.0 μm. The electrolyte salt and the thickness of the film layer are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0226] In some embodiments, the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2, and the thickness of the film layer is 2.0 μm to 4.0 μm. The electrolyte salt and the thickness of the film layer are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0227] In some embodiments, the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, and the mass percentage of the nickel element is 70 wt% to 100 wt%. The electrolyte salt and the mass percentage of the nickel element are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0228] In some embodiments, the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2, and the mass percentage of the nickel element is 80 wt% to 95 wt%. The electrolyte salt and the mass percentage of the nickel element are matched, which can improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0229] In some embodiments, when the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.3 to 1.5, the layered transition metal oxide includes at least one of a compound of the formula Li a Ni b Co c M d O e A f 0.3≤b<1, optionally 0.5≤b<1, further optionally 0.75≤b≤0.98. The mass percentage of the nickel element is relatively high, so that the interface performance of the layered transition metal oxide and the electrolyte is relatively active, and when the ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is in the above range, the sulfimide salt can improve the interface stability of the layered transition metal oxide and the electrolyte, reduce the risk of side reactions, and improve the cycle performance of the cylindrical battery cell 7.

[0230] For example, b can be 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 a range composed of any two of the above values.

[0231] In some embodiments, the sulfimide salt includes an anion of the formula A,

[0232] In formula A, R1and R2each independently include a halogen atom or a C1 to C6 haloalkyl group.

[0233] The sulfimide salt of the above material has excellent thermal stability, which is conducive to reducing the corrosion of the electrolyte salt to the shell 20 and improving the use reliability and cycle performance of the battery cell.

[0234] In some embodiments, the halogen atom includes a fluorine atom.

[0235] In some embodiments, the C1 to C6 haloalkyl group includes a C1 to C6 fluoroalkyl group.

[0236] In some embodiments, R1and R2each independently include a fluorine atom or a C1 to C3 fluoroalkyl group. The above material is easy to dissociate active ions, and the viscosity of the electrolyte salt is relatively low, which is conducive to improving the liquid-phase transport capacity of the electrolyte and improving the kinetic performance of the electrolyte.

[0237] For example, the anion of formula A includes one or more of an anion of formula A-1 to an anion of formula A-5,

[0238] Optionally, the anion of formula A includes one or more of an anion of formula A-1 to an anion of formula A-2,

[0239] The film layer can play a protective role on the shell body. The material of the shell body can be various, such as the base material of the shell body including but not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the shell body includes steel, for example, stainless steel, which has excellent mechanical strength and is not easy to deform, and can further improve the use reliability of the cylindrical battery monomer 7. In the embodiments of the present application, the base material is the material with the largest proportion, and of course, the shell body can also be composed of steel material.

[0240] The shell 20 includes a shell body 21 and an end cover 22. The shell body 21 can include a shell body, in which case the shell body 21 includes a shell body and a film layer; the end cover 22 can include a shell body, in which case the end cover 22 includes a shell body and a film layer; the shell body 21 and the end cover 22 both include a shell body.

[0241] In some embodiments, the electrolyte includes a chain ester solvent, and the mass percentage of the chain ester solvent in the electrolyte is greater than or equal to 25.5wt%.

[0242] In some embodiments, the cylindrical battery monomer 7 includes a shell 20, an electrode assembly 10, and an electrolyte, the shell 20 containing the electrode assembly 10 and the electrolyte, wherein the shell 20 is a cylindrical structure; the electrolyte includes a chain ester solvent, and the mass percentage of the chain ester solvent in the electrolyte is greater than or equal to 25.5wt%.

[0243] The mass percentage of the chain ester solvent is greater than or equal to 25.5wt%, so that the conductivity of the electrolyte is relatively high, which is beneficial to improve the liquid-phase transmission capacity of the active ion and the rapid charging and discharging capacity of the cylindrical battery monomer 7, thereby improving the rate performance of the cylindrical battery monomer 7; however, such a solvent may face decomposition and gas production problems during the cyclic charging and discharging process of the cylindrical battery monomer 7, but the shell 20 of the cylindrical battery monomer 7 adopts a cylindrical structure, which can uniformly disperse the pressure inside the cylindrical battery monomer 7, so that the stress of the shell 20 is uniform, which can effectively increase the pressure resistance of the shell 20, thereby improving the use reliability of the cylindrical battery monomer 7;

[0244] On the other hand, the electrode assembly 10 is accompanied by extrusion and backflow of the electrolyte during the cyclic charging and discharging process. Since the shell 20 adopts a cylindrical structure, the axial dimension of the cylindrical battery monomer 7 can be much larger than the radial dimension, so that the electrolyte has a long axial backflow path and is not easy to fully infiltrate the electrode assembly 10. In the embodiment of the application, the electrolyte adopts a chain ester solvent, and the mass percentage of the chain ester solvent is greater than or equal to 25.5wt%, so that the viscosity of the electrolyte system is relatively low, and the electrolyte is more likely to flow to infiltrate the electrode assembly 10, thereby improving the rapid charging and discharging capability of the cylindrical battery monomer 7, and further improving the rate performance of the cylindrical battery monomer 7.

[0245] Therefore, by using the specific electrolyte system and the cylindrical shell 20 together, the embodiment of the application can improve the rate performance and use reliability of the cylindrical battery monomer 7.

[0246] In some embodiments, the mass percentage of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%, which can be 25.5wt% to 70wt%, and further can be 42.5wt% to 70wt%. When the mass percentage of the chain ester solvent is in the above range, the rate performance and use reliability of the battery monomer 7 can be further improved, and the cycle performance of the battery monomer 7 can be further improved.

[0247] For example, the mass percentage of the chain ester solvent in the electrolyte is 25.5wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 32wt%, 35wt%, 38wt%, 40wt%, 42wt%, 45wt%, 48wt%, 50wt%, 52wt%, 55wt%, 58wt%, 60wt%, 62wt%, 65wt%, 68wt%, 70wt%, 72wt%, 75wt%, 76.5wt%, or a range composed of any two of the above values.

[0248] In some embodiments, the chain ester solvent includes a chain carbonate. The chain carbonate can improve the electrical conductivity of the electrolyte, improve the liquid-phase transport kinetics of the electrolyte, and further improve the rate performance and use reliability of the cylindrical battery monomer 7.

[0249] In some embodiments, the mass percentage of the chain carbonate in the electrolyte is 4wt% to 70wt%, which can be 4wt% to 42.5wt%, and can be 8.5wt% to 35wt%. When the mass percentage of the chain carbonate is in the above range, the electrical conductivity of the electrolyte can be improved, the liquid-phase transport kinetics of the electrolyte can be improved, the rate performance and use reliability of the battery monomer 7 can be further improved, and the cycle performance of the battery monomer 7 can be further improved.

[0250] For example, the mass percentage of the chain carbonate in the electrolyte is 4wt%, 4.5wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, or a range between any two of the above values.

[0251] In some embodiments, the chain carbonate includes a compound of Formula I,

[0252] In Formula I, R 11 and R 12 each independently includes a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. When the chain carbonate is of the above material, the rate performance and use reliability of the cylindrical battery cell 7 can be further improved, and the cycle performance of the cylindrical battery cell 7 can be further improved.

[0253] In some embodiments, R 11 and R 12 each independently includes a C1 to C3 alkyl group or a C1 to C3 haloalkyl group. When the chain carbonate is of the above material, the rate performance and use reliability of the cylindrical battery cell 7 can be further improved, and the cycle performance of the cylindrical battery cell 7 can be further improved.

[0254] For example, the chain carbonate includes one or more of a compound of Formula I-1 to a compound of Formula I-6,

[0255] Optionally, the chain carbonate includes a compound of Formula I-1,

[0256] For example, the chain carbonate includes a compound of Formula I-1, and the mass percentage of the compound of Formula I-1 in the electrolyte is 4wt% to 42.5wt%, optionally 8.5wt% to 35wt%.

[0257] In some embodiments, the chain ester solvent further includes a chain carboxylic acid ester. The chain carboxylic acid ester and the chain carbonate are used in combination, which can improve the electrical conductivity of the electrolyte, improve the liquid-phase transport kinetics of the electrolyte, further improve the rate performance and use reliability of the cylindrical battery cell 7, and further improve the cycle performance of the cylindrical battery cell 7. Of course, the chain carboxylic acid ester can also be used alone as a solvent system.

[0258] In some embodiments, the mass percentage content of the chain carboxylic ester in the electrolyte is 4wt% to 70wt%, optionally 8.5wt% to 60wt%, optionally 20wt% to 55wt%. When the mass percentage content of the chain carboxylic ester in the electrolyte is within the above range, the conductivity of the electrolyte can be improved, the liquid-phase transport kinetics of the electrolyte can be improved, and the rate performance and use reliability of the battery cell 7 can be further improved.

[0259] For example, the mass percentage content of the chain carboxylic ester in the electrolyte is 4wt%, 4.5wt%, 5wt%, 8wt%, 8.5wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 22wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, or a range formed by any two of the above values.

[0260] In some embodiments, the chain carboxylic ester includes a compound shown in Formula II,

[0261] In Formula II,

[0262] R 21 including a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a C1 to C3 halogenated alkyl group;

[0263] R 22 including a C1 to C3 alkyl group or a C1 to C3 halogenated alkyl group.

[0264] In some embodiments, R 21 including a hydrogen atom, a fluorine atom, a C1 to C3 alkyl group, or a C1 to C3 fluorinated alkyl group.

[0265] In some embodiments, R 22 including a C1 to C3 alkyl group or a C1 to C3 fluorinated alkyl group.

[0266] For example, the chain carboxylic ester includes one or more of a compound shown in Formula II-1 to a compound shown in Formula II-6,

[0267] For example, the chain carboxylic ester includes one or more of a compound shown in Formula II-1 to a compound shown in Formula II-6,

[0268] The chain carboxylic ester can include various options,

[0269] For example, the chain carboxylic ester includes a compound shown in Formula II-2, and the mass percentage content of the compound shown in Formula II-2 in the electrolyte is 20wt% to 55wt%.

[0270] For another example, the chain carboxylic acid ester includes the compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0271] For another example, the chain carboxylic acid ester includes the compound shown in Formula II-2 and the compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0272] For another example, the chain carboxylic acid ester includes the compound shown in Formula II-2 and the compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0273] For another example, the chain carboxylic acid ester includes the compound shown in Formula II-2 and the compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0274] For another example, the chain carboxylic acid ester includes the compound shown in Formula II-2 and the compound shown in Formula II-3, and the mass percentage of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0275] The shell 20 is in a cylindrical structure, and the shell 20 includes a shell body 21 which can also be in a cylindrical structure. The shell 20 can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the shell 20 can be made of steel, such as stainless steel. The shell body 21 can be made of steel, such as stainless steel. The end cover 22 can be in a shape that is suitable for the shell body 21 to fit the shell body 21. The end cover 22 can be made of the same material as the shell body 21 or a different material. Optionally, the end cover 22 can be made of a material with certain hardness and strength, such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc. so that the end cover 22 is less likely to be deformed when subjected to extrusion and collision, and the cylindrical battery cell 7 can have higher structural strength and improved reliability. Optionally, the end cover 22 can be made of steel, such as stainless steel. In the embodiments of the present application, the material with the largest proportion is the base material.

[0276] In some embodiments, the shell 20 includes a shell body 21 and an end cover 22, the shell body 21 includes a side wall 212 and an end wall 211 connected to the side wall 212, the shell body 21 has an opening, and the end cover 22 is connected to the side wall 212 and covers the opening, and the end cover 22 and the end wall 211 are opposite along the axial direction of the shell 20.

[0277] In some embodiments, the side wall 212 and the end wall 211 are formed in one piece.

[0278] In some embodiments, the side wall 212 can be made of steel, and the thickness of the side wall 212 can be 0.30mm to 1.2mm, or 0.30mm to 0.55mm. When the thickness of the side wall 212 is within the above range, the side wall 212 has higher strength and better ability to withstand pressure, which can effectively reduce the risk of deformation of the side wall 212 and the risk of swelling of the cylindrical battery cell 7, thereby improving the reliability of the cylindrical battery cell 7.

[0279] In some embodiments, the thickness of the side wall 212 can be 0.30mm, 0.31mm, 0.32mm, 0.35mm, 0.38mm, 0.4mm, 0.45mm, 0.48mm, 0.5mm, 0.55mm, 0.6mm, 0.65mm, 0.7mm, 0.75mm, 0.8mm, 0.85mm, 0.9mm, 0.95mm, 1mm, 1.05mm, 1.1mm, 1.15mm, 1.5mm, or a range defined by any two of the above values.

[0280] In some embodiments, the base material of the side wall 212 includes steel, the thickness of the side wall 212 is 0.30 mm to 1.2 mm, and the mass percentage of the chain ester solvent is 25.5 wt% to 76.5 wt%. When the mass percentage of the chain ester solvent is in the above range, the rate performance of the cylindrical battery cell 7 can be improved, but a certain amount of gas is generated in the cylindrical battery cell 7, so that the cylindrical battery cell 7 has a risk of swelling. When the thickness of the shell 20 is in the above range, the shell 20 has high strength and can bear stronger pressure, which can effectively alleviate the risk of deformation of the shell 20 and reduce the risk of swelling of the cylindrical battery cell 7, thereby improving the use reliability of the cylindrical battery cell 7 and improving the cycle performance of the cylindrical battery cell 7.

[0281] In some embodiments, the base 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 percentage of the chain ester solvent is 25.5 wt% to 70 wt%. When the thickness of the shell 20 and the mass percentage of the chain ester solvent are matched as above, the rate performance and use reliability of the cylindrical battery cell 7 can be improved, and the cycle performance of the cylindrical battery cell 7 can be improved.

[0282] FIG. 6 is a cross-sectional view of a cylindrical battery cell 7 according to some embodiments of the present application; and FIG. 7 is an enlarged view of the cylindrical battery cell 7 of FIG. 6 at position A.

[0283] As shown in FIGS. 6 and 7, in some embodiments, the shell 20 includes a housing 21 and an end cover 22. The housing 21 has an opening, and the end cover 22 is connected to the housing 21 and covers the opening. The end cover 22 is provided with a pressure relief mechanism 220.

[0284] When a short circuit, overcharge, or the like occurs, the electrolyte and the active material react and release gas and heat. The pressure relief mechanism 220 is configured to deform when the internal pressure or temperature of the shell 20 reaches a threshold value, so that the internal space of the shell 20 communicates with the external space to release the pressure or temperature in the shell 20. The deformation of the pressure relief mechanism 220 includes but is not limited to rupture, melting, and the like. The threshold value is different according to different design requirements. The threshold value can depend on the material of one or more of the positive electrode plate, the negative electrode plate, the electrolyte, and the separator in the cylindrical battery cell 7.

[0285] In embodiments of the present application, the deformation of the pressure relief mechanism 220 can be triggered by the internal pressure of the shell 20, or by the internal temperature of the shell 20, or by both the internal pressure and the internal temperature of the shell 20.

[0286] As an example, as the gas within the housing 20 continues to accumulate, the internal pressure of the housing 20 can reach and exceed a pressure threshold. In the case that the internal pressure of the housing 20 reaches the threshold, the pressure relief mechanism 220 deforms under the action of the internal pressure to communicate the internal space of the housing 20 with the external space, and the gas within the housing 20 can be discharged, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0287] As an example, when the electrolyte and the active material react and release heat rapidly, the internal temperature of the housing 20 can rise, and the rise in temperature can also cause the internal pressure of the housing 20 to rise. In the case that the internal temperature of the housing 20 reaches the threshold, the pressure relief mechanism 220 can deform under the action of the temperature and the pressure to communicate the internal space of the housing 20 with the external space, and the gas within the housing 20 can be discharged, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0288] In the case that the internal pressure or the temperature of the housing 20 reaches the threshold, the embodiments of the present application can use the deformation of the pressure relief mechanism 220 to communicate the internal space of the housing 20 with the external space, and then discharge the internal gas and the internal pressure of the housing 20, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0289] In some embodiments, the end cover 22 is provided with a recess 221, and the bottom wall of the recess 221 is a weak portion 222. The weak portion 222 is configured to break when the internal pressure of the cylindrical battery cell 7 reaches the threshold, so as to discharge the internal pressure.

[0290] After the weak portion 222 breaks, a channel is formed for the internal pressure to be discharged. After the weak portion 222 breaks, the internal gas of the cylindrical battery cell 7 can be discharged outward from the broken portion, in this way, the cylindrical battery cell 7 can be depressurized under controllable pressure, thereby avoiding potential more serious accidents.

[0291] In some embodiments, the base material of the weak portion 222 includes steel, and the thickness of the weak portion 222 is 0.01mm to 0.3mm; optionally, 0.05mm to 0.2mm. When the thickness of the weak portion 222 is in the above range, the weak portion 222 has higher strength and stronger pressure bearing capacity, which can effectively improve the pressure resistance of the cylindrical battery cell 7 and improve the use reliability of the cylindrical battery cell 7.

[0292] Exemplarily, the thickness of the weakened portion 222 can be 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 a range formed by any two of the above values.

[0293] In some embodiments, the base material of the weakened portion 222 includes steel, and the thickness of the weakened portion 222 is 0.01 mm to 0.3 mm, and the mass percentage of the chain ester solvent is 25.5 wt% to 76.5 wt%. When the mass percentage of the chain ester solvent is in the above range, the rate performance of the cylindrical battery cell 7 can be improved, but a certain amount of gas is generated in the cylindrical battery cell 7, so that the cylindrical battery cell 7 has a risk of swelling. When the thickness of the weakened portion 222 in the above range, the strength of the weakened portion 222 is higher, and the weakened portion 222 has a stronger ability to withstand pressure, which can effectively improve the pressure resistance of the cylindrical battery cell 7 and improve the use reliability of the cylindrical battery cell 7.

[0294] In some embodiments, the base material of the weakened portion 222 includes steel, and the thickness of the weakened portion 222 is 0.05 mm to 0.2 mm, and the mass percentage of the chain ester solvent is 25.5 wt% to 70 wt%. The thickness of the shell 20 and the mass percentage of the chain ester solvent are matched as described above, which can improve the rate performance and use reliability of the cylindrical battery cell 7.

[0295] In some embodiments, the organic solvent can further include, but is not limited to, at least one of cyclic carbonate, butylene carbonate (BC), fluoroethylene carbonate (FEC), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), diethyl sulfone (ESE). Optionally, the organic solvent further includes cyclic carbonate. Exemplarily, the cyclic carbonate includes at least one of ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC).

[0296] In the present application, the qualitative and quantitative detection of each substance or element in the electrolyte can be carried out by using suitable equipment and methods known to those skilled in the art. The relevant detection methods can refer to domestic and foreign detection standards, domestic and foreign enterprise standards, etc. Those skilled in the art can also adaptively change certain detection steps / instrument parameters from the perspective of detection accuracy to obtain more accurate detection results. One detection method can be used for qualitative or quantitative determination, or several detection methods can be used for qualitative or quantitative determination.

[0297] In the embodiments of the present application, the types and contents of the inorganic components / lithium salt in the electrolyte are the meanings known in the art, and can be detected by using the devices and methods known in the art, for example, the qualitative or quantitative analysis of the inorganic components / lithium salt in the electrolyte can be performed by ion chromatography according to the standard JY / T020-1996 "General Ion Chromatography Analysis Method". In the embodiments of the present application, the newly prepared electrolyte can be taken as the sample, or the free electrolyte obtained from the battery which has been discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC) by reverse disassembly can be taken as the sample, and the ion chromatography analysis method is used for detection.

[0298] In the embodiments of the present application, the types and contents of the organic components in the electrolyte are the meanings known in the art, and can be detected by using the devices and methods known in the art, for example, the qualitative and quantitative analysis of the organic components in the electrolyte can be performed by gas chromatography according to the standard GB / T9722-2006 "General Gas Chromatography Method for Chemical Reagents". In the embodiments of the present application, the newly prepared electrolyte can be taken as the sample, or the free electrolyte obtained from the battery which has been discharged (discharged to the lower limit cutoff voltage so that the charged state of the battery is about 0% SOC) by reverse disassembly can be taken as the sample, and the ion chromatography analysis method is used for detection.

[0299] In the embodiments of the present application, the thickness of the weak portion 222 is the meaning known in the art, and can be detected by using the devices and methods known in the art, for example, the thickness can be tested by using a micrometer.

[0300] In the embodiments of the present application, the thickness of the film layer is the meaning known in the art, and can be detected by using the devices and methods known in the art, for example, the film layer thickness at different positions can be tested by using an X-ray thickness gauge, and the average value is taken as the thickness of the film layer.

[0301] In the embodiments of the present application, the types and contents of the elements in the film layer are the meanings known in the art, and can be detected by using the devices and methods known in the art, for example, the types and content proportions of the elements on the surface of the film layer can be detected by using a spectrometer and an electron scanning microscope, and the types and content proportions of the elements on the surface of the film layer are basically the same as those in the film layer, so that the types and contents of the elements in the film layer are characterized by detecting the types and content proportions of the elements on the surface of the film layer.

[0302] Embodiments

[0303] The following examples describe the present application in more detail, which are only used for illustrative purposes, because various modifications and changes within the scope of the present application are obvious to those skilled in the art. 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 synthesized according to conventional methods and used directly without further purification, and the instruments used in the examples are commercially available.

[0304] Example 1

[0305] 1. Preparation of positive electrode sheet

[0306] The positive electrode sheet includes a positive current collector and a positive film layer, the positive film layer is located on both sides of the positive current collector, the positive current collector is an aluminum foil, and the positive film layer is a film layer formed by uniformly coating a positive slurry (the solvent is N-methyl pyrrolidone NMP) on the surface of the positive current collector aluminum foil, drying and cold pressing. The positive film layer includes positive active material, conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) in a weight ratio of 96.5:2:1.5.

[0307] The positive active material includes a compound with a molecular formula of LiNi 0.9 Co 0.05 Mn 0.05 O2(Ni90).

[0308] 2. Preparation of negative electrode sheet

[0309] The negative electrode sheet includes a negative current collector and a negative film layer, the negative film layer is located on both sides of the negative current collector, the negative current collector is a copper foil, and the negative film layer is a film layer formed by uniformly coating a negative slurry (the solvent is deionized water) on the surface of the negative current collector copper foil, drying and cold pressing. The negative film layer includes negative active material, binder styrene butadiene rubber (SBR), thickening agent sodium carboxymethyl cellulose (CMC-Na) and conductive agent acetylene black in a weight ratio of 96.2:1.8:1.2:0.8.

[0310] The negative active material includes artificial graphite and silicon-based material (specifically silicon-carbon compound), and the content of silicon element in the negative film layer is 5%.

[0311] 3. Separation film

[0312] The separation film is a polypropylene (PP) film layer.

[0313] 4. Preparation of electrolyte

[0314] The electrolyte comprises an organic solvent and a lithium salt, the organic solvent comprises a chain ester solvent, a cyclic ester solvent (ethylene carbonate), the chain ester solvent comprises a chain carbonate (dimethyl carbonate DMC) and a chain carboxylic acid ester (methyl acetate, ethyl acetate with a mass ratio of 1:1), the mass ratio of the chain carbonate, the chain carboxylic acid ester and the ethylene carbonate is 3:4:3, and the lithium salt comprises lithium hexafluorophosphate LiPF6 and lithium bisfluorosulfonylimide LiFSI. After the dimethyl carbonate DMC, the methyl acetate and the ethyl acetate are mixed in the above mass ratio, the lithium salt that is fully dried is then dissolved in the mixed organic solvent to prepare the electrolyte, the molar concentration of the lithium hexafluorophosphate LiPF6 is 0.6 mol / L, and the molar concentration of the lithium bisfluorosulfonylimide LiFSI is 0.4 mol / L.

[0315] 5. Preparation of the cylindrical battery monomer

[0316] The positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence, the separator is arranged between the positive electrode sheet and the negative electrode sheet to play a separation role, the positive electrode sheet, the separator and the negative electrode sheet are wound to obtain an electrode assembly; the electrode assembly is arranged in a cylindrical shell, electrolyte is injected after drying, and the cylindrical battery monomer is obtained through processes such as vacuum packaging, standing, formation and shaping, wherein the shell comprises a shell body and an end cover, the shell body comprises an integral side wall and an end wall, the side wall surrounds the electrode assembly, the end cover and the end wall are opposite along the axial direction of the shell, the side wall comprises a shell body and a film layer, the film layer is arranged on two surfaces of the shell body, the shell body comprises stainless steel, the thickness of the film layer is 3 μm, and the film layer comprises 90 wt% of nickel element, 2 wt% of iron element and 5 wt% of carbon element.

[0317] Comparative Example 1

[0318] The cylindrical battery monomer is prepared by using a method similar to that of Example 1, except that the lithium salt comprises 0.9 mol / L of lithium hexafluorophosphate LiPF6, and the side wall does not comprise a film layer.

[0319] Examples 2-1 to 2-11

[0320] The cylindrical battery monomer is prepared by using a method similar to that of Example 1, except that the composition of the lithium salt is adjusted.

[0321] Examples 3-1 and 3-2

[0322] The cylindrical battery monomer is prepared by using a method similar to that of Example 1, except that the type of the sulfonimide salt in the lithium salt is adjusted.

[0323] Performance test

[0324] 1. Cycle performance test of the battery monomer

[0325] The cylindrical battery cell prepared in each example and comparative example was charged at 45°C at a constant current of 0.5C to a charge cut-off voltage of 4.25V, then charged at a constant voltage until the current was less than or equal to 0.05C, rested for 5 min, then discharged at a constant current of 0.33C to a discharge cut-off voltage of 2.5V, and rested for 5 min, which was one charge-discharge cycle. The battery cell was subjected to the above cycle charge-discharge test, and the capacity retention rate after 800 cycles was calculated.

[0326] 2. Battery storage gas production test

[0327] The cylindrical battery cell prepared in each example and comparative example was charged at 25°C at a constant current of 0.5C to 4.25V, then charged at a constant voltage until the current was less than or equal to 0.05C, and then the battery was stored at 60°C for 100 days, and the internal pressure (Mpa) of the battery was detected using an external pressure gauge.

[0328] 3. Internal resistance test of battery cell

[0329] The cylindrical battery cell prepared in each example and comparative example was charged at 25°C at a constant current of 1C to 4.25V, then charged at a constant voltage until the current was less than or equal to 0.05C, and then discharged at 1C for 30 min, and the capacity of the battery cell was adjusted to 50% state of charge (SOC).

[0330] The positive and negative pens of the TH2523A AC internal resistance tester were respectively contacted with the positive and negative electrodes of the battery cell, and the internal resistance value (mΩ) of the battery cell was read by the internal resistance tester.

[0331] Test results

[0332] The test results are shown in Table 1.

[0333] Table 1

[0334] In Table 1,

[0335] Formula A-1 represents a bis-fluorosulfonylimide ion, and the corresponding cation is a lithium ion,

[0336] Formula A-2 represents a bis-trifluoromethanesulfonylimide ion, and the corresponding cation is a lithium ion,

[0337] Formula A-3 represents a (fluorosulfonyl)(trifluoromethanesulfonyl)imido ion, and the corresponding cation is a lithium ion.

[0338] As can be seen from Table 1,

[0339] The shell of Comparative Example 1 is a stainless steel shell, which is easily corroded by lithium hexafluorophosphate. Compared with Comparative Example 1, the shell of the present application is provided with a film layer containing nickel on the surface of the shell, which can effectively improve the corrosion resistance of the shell, reduce the corrosion risk of the shell caused by the decomposition of lithium hexafluorophosphate to produce hydrofluoric acid, and improve the cycle performance of the cylindrical battery monomer. In addition, it can reduce the internal pressure of the cylindrical battery monomer, reduce the gas production, and improve the use reliability of the cylindrical battery monomer.

[0340] Examples 2-1 to 2-11 can further improve the cycle performance of the cylindrical battery monomer, reduce the internal pressure of the cylindrical battery monomer, reduce the gas production, and improve the use reliability of the cylindrical battery monomer by adjusting the composition of the lithium salt. In addition, it can improve the ion liquid phase transmission ability of the electrolyte system, reduce the resistance, and improve the rate performance. Examples 3-1 and 3-2 can further improve the cycle performance of the cylindrical battery monomer, reduce the internal pressure of the cylindrical battery monomer, reduce the gas production, and improve the use reliability of the cylindrical battery monomer by adjusting the composition of the sulfonimide salt. In addition, it can improve the ion liquid phase transmission ability of the electrolyte system, reduce the resistance, and improve the rate performance.

[0341] Example 4

[0342] The cylindrical battery monomer was prepared by a method similar to Example 1, except that the thickness of the film layer in the side wall of the shell was adjusted.

[0343] Example 5

[0344] The cylindrical battery monomer was prepared by a method similar to Example 1, except that the composition of the film layer in the side wall of the shell was adjusted.

[0345] The test results are shown in Table 2.

[0346] Table 2

[0347] As can be seen from Table 2, the electrolyte system in the present application is suitable for metal shells with different film thicknesses, such as 1.5 μm to 6.0 μm, and optionally 2.0 μm to 4.0 μm. When the film layer meets the above range, the battery has excellent cycle performance and use reliability.

[0348] The electrolyte system in the present application is suitable for metal shells with different nickel content film layers, such as 70wt% to 100wt%, and optionally 80wt% to 95wt%. When the mass percentage of nickel element meets the above range, the battery has excellent cycle performance and use reliability.

[0349] Examples 6-1 and 6-2

[0350] A cylindrical battery cell was prepared by using a method similar to that of Example 1, except that the mass percentage of silicon element in the negative electrode film layer was adjusted.

[0351] The test results are shown in Table 3.

[0352] Table 3

[0353] As shown in Table 3, by adjusting the mass percentage of silicon element in the negative electrode film layer, the cycle performance of the cylindrical battery cell can be further improved, the internal pressure of the cylindrical battery cell can be reduced, the gas production can be reduced, and the use reliability of the cylindrical battery cell can be improved.

[0354] Although the illustrative implementations have been demonstrated and described, it will be understood by those skilled in the art that the above-described implementations are not to be construed as limiting, and that changes, alternatives and modifications can be suggested by those skilled in the art, without departing from the spirit, principles and scope of the present application.

Claims

1. A cylindrical battery cell, comprising an electrolyte, an electrode assembly, and a housing, the housing containing the electrolyte and the electrode assembly, wherein the electrolyte comprises an electrolyte salt, the electrolyte salt comprising a hexafluorophosphate salt; the housing comprises a housing body and a film layer, the film layer being disposed at least on a surface of the housing body facing the electrode assembly, and a base element of the film layer being a nickel element. The molar concentration of the hexafluorophosphate salt is less than or equal to 1.2 mol / L. The molar concentration of the hexafluorophosphate salt is less than or equal to 0.9 mol / L.

2. The cylindrical battery cell of claim 1, wherein, The molar concentration of the hexafluorophosphate salt is 0.2 mol / L to 0.8 mol / L.

3. The cylindrical battery cell of claim 2, wherein, The molar concentration of the hexafluorophosphate salt is 0.3 mol / L to 0.7 mol / L.

4. The cylindrical battery cell of claim 3, wherein, The thickness of the film layer is 1.5 μm to 6.0 μm.

5. The cylindrical battery cell of claim 4, wherein, The thickness of the film layer is 2.0 μm to 4.0 μm.

6. The cylindrical battery cell according to any one of claims 1 to 5, wherein, The mass percentage of the nickel element in the film layer is 70 wt% to 100 wt%.

7. The cylindrical battery cell of claim 6, wherein, The mass percentage of the nickel element in the film layer is 80 wt% to 95 wt%.

8. The cylindrical battery cell according to any one of claims 1 to 7, wherein, The film layer further comprises an iron element, the mass percentage of the iron element in the film layer being 0.1 wt% to 10 wt%; and / or 9. The cylindrical battery cell of claim 8, wherein, The film layer further comprises a carbon element, the mass percentage of the carbon element in the film layer being 0.1 wt% to 15 wt%.

10. The cylindrical battery cell according to any one of claims 1 to 9, wherein, The mass percentage of the iron element in the film layer is 1 wt% to 5 wt%. The mass percentage of the carbon element in the film layer is 4 wt% to 12 wt%.

11. The cylindrical battery cell of claim 10, wherein, The ratio of the molar concentration of a sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6.

12. The cylindrical battery cell according to claim 10 or 11, wherein, The ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2.

13. The cylindrical battery cell of any one of claims 1 to 12, wherein, The ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.3 to 1.

5.

14. The cylindrical battery cell of claim 13, wherein, The molar concentration of the electrolyte salt is 0.5 mol / L to 2 mol / L.

15. The cylindrical battery cell of claim 14, wherein, The molar concentration of the electrolyte salt is 0.6 mol / L to 1.5 mol / L.

16. The cylindrical battery cell of any one of claims 13-15, wherein, In formula A, R1 and R2 each independently comprise a halogen atom or a C1 to C6 haloalkyl group.

17. The cylindrical battery cell of claim 16, wherein, The halogen atom comprises a fluorine atom; and / or 18. The cylindrical battery cell of any one of claims 13-17, wherein, The sulfonimide salt includes an anion represented by Formula A, The C1 to C6 haloalkyl group comprises a C1 to C6 fluoroalkyl group.

19. The cylindrical battery cell of claim 18, wherein, R1 and R2 each independently comprise a fluorine atom or a C1 to C3 fluoroalkyl group. The base material of the housing body is steel.

20. The cylindrical battery cell of claim 18 or 19, wherein, The electrode assembly comprises a negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer disposed on at least one side of the negative electrode current collector and containing a negative electrode active material, the negative electrode active material comprising a silicon element.

21. The cylindrical battery cell of any one of claims 18-20, wherein, Anions of Formula A include one or more of anions of Formula A-1 to A-5, 22. The cylindrical battery cell of claim 21, wherein, Anions of Formula A include one or more of anions of Formula A-1 to anions of Formula A-2, 23. The cylindrical battery cell of any one of claims 1 to 22, wherein, The mass percentage of the silicon element in the negative electrode film layer is 1% to 32%.

24. The cylindrical battery cell of any one of claims 1 to 23, wherein, The electrolyte comprises a chain ester solvent, the mass percentage of the chain ester solvent in the electrolyte being greater than or equal to 25.5 wt%.

25. The cylindrical battery cell of claim 24, wherein, The mass percentage of the chain ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%.

26. The cylindrical battery cell of any one of claims 1 to 25, wherein, ​ 27. The cylindrical battery cell of claim 26, wherein, ​ 28. The cylindrical battery cell of claim 26 or 27, wherein, The chain ester solvent includes a chain carbonate, and the mass percentage of the chain carbonate in the electrolyte is 4wt% to 70wt%.

29. The cylindrical battery cell of claim 28, wherein, The chain carbonate includes a compound represented by Formula I, In formula I, R 11 and R 12 each independently comprises a C1to C3alkyl group or a C1to C3haloalkyl group.

30. The cylindrical battery cell of claim 29, wherein, R 11 and R 12 each independently comprises a C1to C3alkyl group or a C1to C3fluoroalkyl group.

31. The cylindrical battery cell of claim 29 or 30, wherein, The chain carbonate includes one or more of compounds represented by Formula I-1 to Formula I-6, 32. The cylindrical battery cell of claim 31, wherein, The chain carbonate includes a compound represented by Formula I-1, 33. The cylindrical battery cell of any one of claims 26-32, wherein, The chain ester solvent further includes a chain carboxylic acid ester, and the mass percentage of the chain carboxylic acid ester in the electrolyte is 4wt% to 70wt%.

34. The cylindrical battery cell of claim 33, wherein, The mass percentage of the chain carboxylic acid ester in the electrolyte is 8.5wt% to 60wt%.

35. The cylindrical battery cell of claim 33 or 34, wherein, The chain carboxylate includes a compound represented by Formula II, In formula II, R 21 comprises a hydrogen atom, a halogen atom, a Ci to C3 alkyl group or a Ci to C3 haloalkyl group; R 22 comprises C1to C3alkyl or C1to C3haloalkyl.

36. The cylindrical battery cell of claim 35, wherein, R 21 comprises a hydrogen atom, a fluorine atom, a Ci to C3alkyl group or a Ci to C3fluoroalkyl group; and / or R 22 comprises C1to C3alkyl or C1to C3fluoroalkyl.

37. The cylindrical battery cell of claim 35 or 36, wherein, The chain carboxylate includes one or more of a compound represented by Formula II-1 to a compound represented by Formula II-6, 38. The cylindrical battery cell of claim 37, wherein, The chain carboxylic acid ester includes one or more of a compound shown in formula II-2 and a compound shown in formula II-3.

39. The cylindrical battery cell of claim 38, wherein, The chain carbonate includes a compound represented by Formula I-1, The mass percentage of the compound shown in formula I-1 in the electrolyte is 8.5wt% to 35wt%; The chain carboxylic acid ester includes a compound shown in formula II-2 and a compound shown in formula II-3, and the mass percentage of the compound shown in formula II-2 and the compound shown in formula II-3 in the electrolyte is 20wt% to 55wt%.

40. The cylindrical battery cell of any one of claims 1-39, wherein, The shell includes a casing and an end cover, the casing includes a side wall and an end wall connected to the side wall, the casing has an opening, the end cover is connected to the side wall and covers the opening, and the end cover and the end wall are opposite in the axial direction of the cylindrical battery cell.

41. The cylindrical battery cell of claim 40, wherein, The base material of the side wall is steel, and the thickness of the side wall is 0.30mm to 1.2mm.

42. The cylindrical battery cell of claim 40 or 41, wherein, The side wall and the end wall are integrally formed.

43. The cylindrical battery cell of any one of claims 40-42, wherein, The end cover is provided with a pressure relief mechanism.

44. The cylindrical battery cell of claim 43, wherein, The pressure relief mechanism includes a weak portion, the base material of the weak portion includes steel, and the thickness of the weak portion is 0.01mm to 0.3mm.

45. The cylindrical battery cell of claim 44, wherein, The end cover is provided with a recess, and the bottom wall of the recess is the weak portion.

46. The cylindrical battery cell of any one of claims 40 to 45, further comprising an electrode terminal disposed on the end wall. The cylindrical battery cell includes an electrode assembly accommodated in the casing, the electrode assembly includes first and second tabs of opposite polarity, the first tab is electrically connected to the end wall, and the second tab is electrically connected to the electrode terminal.

47. The cylindrical battery cell of any one of claims 1-46, wherein, The dimension of the shell in the axial direction of the cylindrical battery cell is 1.3 to 2.5 times the dimension of the shell in the radial direction of the cylindrical battery cell.

48. The cylindrical battery cell of any one of claims 1-47, wherein, The dimension of the shell in the axial direction of the cylindrical battery cell is 50mm to 150mm; and / or The dimension of the shell in the radial direction of the cylindrical battery cell is 40mm to 80mm.

49. A battery comprising the cylindrical battery cell of any one of claims 1 to 48.

50. An electrical device comprising the battery of claim 49.

Images