Cylindrical battery cell, battery, and electric device

Abstract

A cylindrical battery cell, a battery, and an electric device. The cylindrical battery cell comprises a metal casing and an electrolyte; the electrolyte is contained in the metal casing; the electrolyte comprises an electrolyte salt; the electrolyte salt comprises hexafluorophosphate and sulfonimide salt; and the molar concentration of hexafluorophosphate is less than or equal to 0.9 mol / L. The use reliability and cycle performance of the cylindrical battery cell 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. 202410536572.5, 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.

[0006] SUMMARY

[0007] 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.

[0008] In a first aspect, the embodiments of the present application provide a cylindrical battery cell, which comprises a metal shell and an electrolyte, the electrolyte is contained in the metal shell, and the electrolyte comprises an electrolyte salt, the electrolyte salt comprises a hexafluorophosphate salt and a sulfonimide salt, and the molar concentration of the hexafluorophosphate salt is less than or equal to 0.9 mol / L.

[0009] Thus, the embodiments of the present application comprise a hexafluorophosphate salt and a sulfonimide salt, so that the thermal stability of the electrolyte system is relatively high, and the molar concentration of the hexafluorophosphate salt is relatively small, and the corrosion ability of the metal shell is reduced, thereby reducing the risk of corrosion of the metal shell and the risk of metal corrosion to generate metal ions in the shell; and the metal shell of the cylindrical battery cell can effectively disperse the acting force in the system, so that the metal 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.

[0010] 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 is within the above range, which can further reduce the corrosion effect on the shell and improve the use reliability and cycle performance of the cylindrical battery cell, etc.

[0011] 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 reduce the corrosion effect on the shell, and improve the use reliability and cycle performance of the cylindrical battery cell.

[0012] 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 in 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, and improve the use reliability and cycle performance of the battery cell.

[0013] 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 in the above range, the stability of the electrolyte salt can be further improved, and the use reliability and cycle performance of the battery cell can be improved.

[0014] 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 in the above range, the stability of the electrolyte salt can be further improved, and the use reliability and cycle performance of the battery cell can be improved.

[0015] 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 in 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; and it is also beneficial to improve the liquid-phase transport capacity of the active ion, thereby improving the kinetic performance of the battery cell.

[0016] 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 in the above range, it is beneficial to further improve the kinetic performance of the battery cell.

[0017] In some embodiments, the metal shell comprises a shell body and a film layer, and the film layer is arranged at least on the surface of the shell body facing the electrolyte, and the base element of the film layer is nickel element. The base element of the film layer is 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, thereby improving the use reliability and cycle performance of the cylindrical battery cell.

[0018] 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 within 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.

[0019] 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 within 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.

[0020] 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 within 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.

[0021] 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 within 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.

[0022] 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%, or optionally 1 wt% to 5 wt%. When the mass percentage content of the iron element is within the above range, the conductivity of the shell is effectively improved, thereby facilitating electron transmission.

[0023] In some embodiments, the film layer further comprises a carbon element, and the mass percentage content of the carbon element in the film layer is 0.1 wt% to 15 wt%, or optionally 4 wt% to 12 wt%. When the mass percentage content of the carbon element is within the above range, the conductivity of the shell is effectively improved, thereby facilitating electron transmission.

[0024] 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 prone to deformation, thereby further improving the use reliability of the cylindrical battery cell.

[0025] In some embodiments, the sulfonimide salt comprises an anion represented by Formula A,

[0026] In Formula A, R1 and R2 each independently comprise a halogen atom or a C1 to C6 halogenated alkyl group.

[0027] Thus, the sulfonimide salt with the above material in the embodiments of the present application has excellent thermal stability, which is conducive to reducing the corrosion of the electrolyte salt to the shell and improving the use reliability and cycle performance of the battery cell.

[0028] In some embodiments, the halogen atom includes a fluorine atom.

[0029] In some embodiments, the C1 to C6 haloalkyl group includes a C1 to C6 fluoroalkyl group.

[0030] In some embodiments, R1 and R2 each independently include a fluorine atom or a C1 to C3 fluoroalkyl group.

[0031] In some embodiments, the anion represented by Formula A includes one or more of an anion represented by Formula A-1 to an anion represented by Formula A-5,

[0032] In some embodiments, the anion represented by Formula A includes one or more of an anion represented by Formula A-1 to an anion represented by Formula A-2,

[0033] In some embodiments, the cylindrical battery cell includes an electrode assembly, the electrode assembly includes a positive electrode tab, the positive electrode tab includes a positive electrode current collector and a positive electrode film layer disposed on at least one side of the positive electrode current collector, the positive electrode film layer includes a positive electrode active material, the positive electrode active material includes a layered transition metal oxide. The sulfonimide salt can improve the interface stability between the layered transition metal oxide and the electrolyte, reduce the risk of side reactions, and improve the cycle performance of the cylindrical battery cell.

[0034] In some embodiments, the layered transition metal oxide includes a chemical formula of Li a Ni b Co c M d O e A f , 0.8≤a≤1.2, 0.3≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M includes at least one of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A includes at least one of N, F, S, and Cl. The sulfonimide salt can improve the interface stability between the layered transition metal oxide and the electrolyte, reduce the risk of side reactions, and improve the cycle performance of the cylindrical battery cell.

[0035] In some embodiments, 0.5≤b<1, and optionally, 0.75≤b≤0.98. The sulfonimide salt can improve the interface stability between the layered transition metal oxide and the electrolyte, reduce the risk of side reactions, and improve the cycle performance of the cylindrical battery cell.

[0036] In some embodiments, the electrolyte includes a chain ester solvent, and a mass percentage of the chain ester solvent in the electrolyte is greater than or equal to 25.5wt%.

[0037] Therefore, the mass percentage content of the chain ester solvent in the embodiments of the present application is greater than or equal to 25.5 wt%, so that the conductivity of the electrolyte is relatively high, which is beneficial to improving the liquid-phase transmission capacity of the active ions and the rapid charging and discharging capacity of the battery cell, thereby improving the rate performance of the battery cell.

[0038] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 25.5 wt% to 76.5 wt%. 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 also be further improved.

[0039] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 25.5 wt% to 70 wt%. 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 also be further improved.

[0040] In some embodiments, the mass percentage content of the chain ester solvent in the electrolyte is 42.5 wt% to 70 wt%. 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 also be further improved.

[0041] In some embodiments, the chain ester solvent includes a chain carbonate, and the mass percentage content of the chain carbonate in the electrolyte is 4 wt% to 70 wt%. When the mass percentage content of the chain carbonate is in the above range, the conductivity of the electrolyte can be improved, the liquid-phase transmission 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 mass percentage content of the chain carbonate in the electrolyte is 4 wt% to 42.5 wt%. When the mass percentage content of the chain carbonate is in the above range, the conductivity of the electrolyte can be improved, the liquid-phase transmission kinetics performance of the electrolyte can be improved, and the rate performance and use reliability of the battery cell can be further improved.

[0043] In some embodiments, the chain carbonate includes a compound shown in Formula I,

[0044] In Formula I, R 11 and R 12 Each independently includes a C1 to C3 alkyl group or a C1 to C3 halogenated alkyl group.

[0045] 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.

[0046] In some embodiments, R 11 and R 12 each independently comprises a C1 to C3 alkyl group or a C1 to C3 fluoroalkyl group.

[0047] In some embodiments, the chain carbonate comprises one or more of a compound represented by Formula I-1 to a compound represented by Formula I-6,

[0048] In some embodiments, the chain carbonate comprises a compound represented by Formula I-1.

[0049] In some embodiments, the chain ester solvent further comprises a chain carboxylic acid ester, and the mass percentage content of the chain carboxylic acid ester in the electrolyte is 4wt% to 70wt%. 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, and further improve the rate performance and use reliability of the battery cell.

[0050] In some embodiments, the mass percentage content of the chain carboxylic acid ester in the electrolyte is 8.5wt% to 60wt%. When the mass percentage content of the chain carboxylic acid ester in the electrolyte 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, and the rate performance and use reliability of the battery cell can be further improved.

[0051] In some embodiments, the chain carboxylic acid ester comprises a compound represented by Formula II,

[0052] In Formula II,

[0053] R 21 comprises a hydrogen atom, a halogen atom, a C1 to C3 alkyl group, or a C1 to C3 haloalkyl group;

[0054] R 22 comprises a C1 to C3 alkyl group or a C1 to C3 haloalkyl group.

[0055] Therefore, the chain carboxylic acid ester and the chain carbonate of the above-mentioned materials used in combination in the embodiments of the present application can further improve the rate performance and use reliability of the battery cell.

[0056] In some embodiments, R 21 comprises a hydrogen atom, a fluorine atom, a C1 to C3 alkyl group, or a C1 to C3 fluoroalkyl group.

[0057] In some embodiments, R 22 comprises a C1 to C3 alkyl group or a C1 to C3 fluoroalkyl group.

[0058] In some embodiments, the chain carboxylate ester includes one or more of a compound shown in Formula II-1 to a compound shown in Formula II-6,

[0059] In some embodiments, the chain carboxylate ester includes one or more of a compound shown in Formula II-2 and a compound shown in Formula II-3.

[0060] In some embodiments, the chain carbonate ester includes a compound shown in Formula I-1,

[0061] The mass percentage content of the compound shown in Formula I-1 in the electrolyte is 8.5wt% to 35wt%;

[0062] The chain carboxylate ester includes a compound shown in Formula II-2 and a compound shown in Formula II-3, and the mass percentage content of the compound shown in Formula II-2 and the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0063] In some embodiments, the metal 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 monomer.

[0064] 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 alleviate the risk of deformation of the side wall and reduce the risk of swelling of the battery monomer, thereby improving the use reliability of the battery monomer.

[0065] 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 monomer can be reduced, thereby improving the use reliability of the battery monomer.

[0066] In some embodiments, the side wall and the end wall are integrally formed.

[0067] 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 metal shell with the external space, and the gas in the metal shell can be discharged, thereby reducing the risk of explosion of the battery monomer.

[0068] 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 monomer and improve the use reliability of the battery monomer.

[0069] In some embodiments, the thickness of the weakened portion is 0.05mm to 0.2mm. When the thickness of the weakened portion is in the above range, the use reliability of the battery cell can be further improved.

[0070] In some embodiments, the end cover is provided with a recess, and a bottom wall of the recess is the weakened portion. This structure is simple and convenient to process.

[0071] In some embodiments, the battery cell further comprises an electrode terminal arranged on the end wall; the battery cell comprises an electrode assembly accommodated in the shell, and the electrode assembly comprises first and second tabs with opposite polarities, the first tab being electrically connected to the end wall, and the second tab being electrically connected to the electrode terminal.

[0072] In some embodiments, the metal shell has an axial dimension along itself which is 1.3 to 2.5 times of a radial dimension of the metal shell along the cylindrical battery cell.

[0073] In some embodiments, the metal shell has an axial dimension along the cylindrical battery cell which is 50mm to 150mm.

[0074] In some embodiments, the metal shell has a radial dimension along the cylindrical battery cell which is 40mm to 80mm.

[0075] In some embodiments, the metal shell has a radial dimension along the cylindrical battery cell which is 40mm to 80mm.

[0075] In some embodiments, the metal shell has a radial dimension along the cylindrical battery cell which is 40mm to 80mm.

[0076] In some embodiments, the metal shell has a radial dimension along the cylindrical battery cell which is 40mm to 80mm. BRIEF DESCRIPTION OF DRAWINGS

[0077] 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 embodiments of the present application, and other drawings can also be obtained by the drawings without paying creative labor for those skilled in the art.

[0078] Fig. 1 is a structural schematic diagram of a vehicle provided by some embodiments of the present application;

[0079] Fig. 2 is an exploded schematic diagram of a battery provided by some embodiments of the present application;

[0080] Fig. 3 is an exploded schematic diagram of a battery module shown in Fig. 2;

[0081] Fig. 4 is a structural schematic diagram of a cylindrical battery cell provided by some embodiments of the present application;

[0082] Fig. 5 is an exploded schematic diagram of a cylindrical battery cell provided by some embodiments of the present application;

[0083] FIG. 6 is a cross-sectional view of a cylindrical battery cell according to some embodiments of the present application;

[0084] FIG. 7 is an enlarged view of the cylindrical battery cell of FIG. 6 at A.

[0085] The drawings are not necessarily to scale.

[0086] The reference signs are explained as follows: X, axial direction; Y, radial direction; 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; 10, electrode assembly; 111, first tab; 112, second tab; 12, main body portion; 20, metal case; 21, housing; 211, end wall; 212, side wall; 22, end cover; 220, pressure relief mechanism; 221, recess; 222, weak portion; 30, electrode terminal; 40, current collecting member. DETAILED DESCRIPTION

[0087] Hereinafter, embodiments of the cylindrical battery cell, the battery, and the electric device according to the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters that are already well known, repeated description of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description 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.

[0088] "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 interger value within the given range, wherein a and b are both integers. For example, the numerical range "0-5" indicates that all integers between 0 and 5 are contemplated herein, and "0-5" is merely a shorthand way of describing each and every integer within the range. In addition, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0089] Unless otherwise indicated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0090] Unless otherwise indicated, all technical features of the present application and optional technical features can be combined with each other to form new technical solutions.

[0091] Unless otherwise indicated, all steps of the present application can be performed in sequence or randomly, and are preferably performed in sequence. For example, a method comprising steps (a) and (b) indicates that the method can comprise steps (a) and (b) performed in sequence, or steps (b) and (a) performed 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.

[0092] 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.

[0093] 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.

[0094] The term "and / or" in the present application is only to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects have an "or" relationship.

[0095] In the embodiments of the present application, the same reference signs represent the same parts, and for the sake of brevity, the detailed description of the same parts is omitted in different embodiments. It should be understood that the thickness, length and width of various components in the embodiments of the present application shown in the drawings, and the overall thickness, length and width of the integrated device are only exemplary and should not constitute any limitation on the present application.

[0096] "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.

[0097] 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.

[0098] As an example, the battery cell can be a cylindrical battery cell, which refers to a battery cell whose appearance presents a cylindrical structure or a structure similar to a cylindrical structure.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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 cross beams and longitudinal beams of the vehicle.

[0103] 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.

[0104] 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 use reliability of the cylindrical battery cell. Moreover, metal ions generated by 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.

[0105] In view of this, the embodiments of the present application propose a cylindrical battery cell. The shell of the cylindrical battery cell is a metal shell. The electrolyte salt in the electrolyte includes hexafluorophosphate and a sulfonimide salt. The introduction of the sulfonimide salt makes the thermal stability of the electrolyte system relatively high, and the molar concentration of the hexafluorophosphate is relatively small, such as less than or equal to 0.9 mol / L, which reduces the corrosion ability of the metal shell, thereby reducing the risk of corrosion of the metal shell and the risk of metal corrosion to generate metal ions in the shell, thereby facilitating the improvement of the use reliability and cycle performance of the cylindrical battery cell.

[0106] The cylindrical battery cell described in the embodiments of the present application is suitable for a battery and an electric device using the battery.

[0107] The cylindrical battery cell, the battery and the electric device disclosed in the embodiments of the present application can be used in an electric device using a battery as a power source or a variety of energy storage systems using a battery as an energy storage element. The electric 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 a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric plane toy, etc. The spacecraft can include an airplane, a rocket, a space shuttle and a spacecraft, etc.

[0108] The following embodiments are described for convenience of illustration, taking a vehicle as an example.

[0109] FIG. 1 is a structural schematic diagram of a vehicle according to some embodiments of the present application.

[0110] 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 the operating power source of the vehicle 1.

[0111] The vehicle 1 can also include a controller 3 and a motor 4, the controller 3 being used to control the battery 2 to supply power to the motor 4, for example, for the power demand of the vehicle 1 during starting, navigation and driving.

[0112] In some embodiments of the present application, the battery 2 can not only be used as the operating power source of the vehicle 1, but also as the driving power source of the vehicle 1, instead of or partially instead of fuel or natural gas to provide driving power for the vehicle 1.

[0113] FIG. 2 is an exploded schematic view of the battery according to some embodiments of the present application. As shown in FIG. 2, the battery 2 includes a box body 5 and a cylindrical battery cell (not shown in FIG. 2), which is contained in the box body 5.

[0114] The box body 5 is used to contain the cylindrical battery cell, and the box body 5 can have various structures. In some embodiments, the box body 5 can include a first box body part 5a and a second box body part 5b, the first box body part 5a and the second box body part 5b being mutually coverable, and the first box body part 5a and the second box body part 5b together defining a containing space 5c for containing the cylindrical battery cell. The second box body part 5b can be a hollow structure with one end open, and the first box body part 5a can be a plate-like structure, the first box body part 5a being coverable to the open side of the second box body part 5b to form the box body 5 with the containing space 5c; or the first box body part 5a and the second box body part 5b can both be hollow structures with one side open, the open side of the first box body part 5a being coverable to the open side of the second box body part 5b to form the box body 5 with the containing space 5c. Of course, the first box body part 5a and the second box body part 5b can have various shapes, such as a cylinder, a cuboid, etc.

[0115] To improve the sealing performance of the first box body part 5a and the second box body part 5b after being connected, a sealing member such as sealing glue, a sealing ring, etc. can be arranged between the first box body part 5a and the second box body part 5b.

[0116] Suppose the first box body part 5a is coverable to the top of the second box body part 5b, the first box body part 5a can also be referred to as an upper box cover, and the second box body part 5b can also be referred to as a lower box body.

[0117] 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 series and in parallel. The multiple cylindrical battery cells can be directly connected in series, in parallel or in a mixed manner, and then the multiple cylindrical battery cells are accommodated in the box 5. Alternatively, the multiple cylindrical battery cells can be 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 and are accommodated in the box 5.

[0118] The cylindrical battery cell can be the smallest unit of the battery.

[0119] FIG. 3 is a structural schematic diagram of the battery module shown in FIG. 2.

[0120] In some embodiments, as shown in FIG. 3, the cylindrical battery cell 7 is multiple, and the multiple cylindrical battery cells 7 are connected in series, in parallel or in a mixed manner to form a battery module 6. Then the multiple battery modules 6 are connected in series, in parallel or in a mixed manner to form a whole and are accommodated in the box.

[0121] The multiple cylindrical battery cells 7 in the battery module 6 can be electrically connected through a busbar component to realize the parallel connection, series connection or mixed connection of the multiple cylindrical battery cells 7 in the battery module. The busbar component can be one or multiple, and each busbar component is used to electrically connect at least two cylindrical battery cells.

[0122] FIG. 4 is a structural schematic diagram of a cylindrical battery cell according to some embodiments of the present application; and FIG. 5 is an exploded schematic diagram of the cylindrical battery cell shown in FIG. 4.

[0123] As shown in FIGS. 4 and 5, in some embodiments, the cylindrical battery cell 7 includes an electrode assembly 10 and a metal shell 20, and the electrode assembly 10 is accommodated in the metal shell 20.

[0124] The metal shell 20 has a cylindrical structure, and the metal shell 20 includes a shell body 21 which has a cylindrical structure. The shape of the electrode assembly 10 is also cylindrical.

[0125] In some embodiments, the size of the metal 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 formed by any two of the above values, of the size of the metal shell 20 along the radial direction Y of the cylindrical battery cell 7. When the metal shell 20 meets the above size requirement, the volume expansion of the electrode assembly 10 can be effectively constrained, the extrusion force on the metal shell 20 is evenly distributed, the metal shell 20 is less likely to deform, and the use reliability of the cylindrical battery cell 7 can be improved.

[0126] Exemplarily, the metal shell 20 has a dimension of 50mm to 150mm along the axial direction X, for example, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm, 120mm, 125mm, 130mm, 135mm, 140mm, 145mm, 150mm, or a range between any two of the above values.

[0127] Exemplarily, the metal 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.

[0128] 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.

[0129] 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.

[0130] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0131] 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, a 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.).

[0132] As an example, when the cylindrical battery cell 7 of the embodiment of the present application is a lithium ion battery, the positive electrode active material can include at least one of the following materials: phosphates, layered transition metal oxides, and modified compounds of each of them; alternatively, the positive electrode active material can include layered transition metal oxides and modified compounds of each of them, which are advantageous to improve 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 a positive electrode film layer of a battery can also be used. These positive electrode active materials can be used alone or in combination of two or more.

[0133] Examples of the phosphates can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0134] The layered transition metal oxide includes a compound of the general formula Li a Ni b Co c M d O e A f and modified compounds of each of them, 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. Alternatively, 0.5≤b<1, and further alternatively, 0.75≤b≤0.98.

[0135] Examples of the layered transition metal oxide can include, but are not limited to, at least one of 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 (which can also be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2O2(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.

[0136] When the cylindrical battery cell 7 of the embodiment of the present application is a sodium ion battery, the positive electrode 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.

[0137] As an example, the positive electrode active material for a sodium ion battery can include at least one of NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, 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 materials, materials of the general formula X p M’ q (PO4) r O x Y 3-x . In the 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.

[0138] In the embodiments of the present application, the modification compound of each of the above-mentioned positive electrode active materials can be a doping modification and / or a surface coating modification, for example, a carbon coating modification, a fast ion conductor coating modification, etc.

[0139] 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 molar content of Li in the listing of the positive electrode active material is the initial state of the material, i.e., the state before feeding, and the positive electrode active material is applied to the battery system. After charging and discharging cycles, the molar content of Li can change.

[0140] In the embodiments of the present application, the molar content of oxygen O in the listing of the positive electrode active material is only the theoretical state value, and the lattice oxygen release will cause the molar content of oxygen O to change. In fact, the molar content of oxygen O will appear to be floating.

[0141] In the embodiments of the present application, the content of elements in the positive electrode active material is 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, testing by inductively coupled plasma atomic emission spectrometry, and measuring by using 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 using a standard curve method.

[0142] 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, a 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, a potassium metal or a sodium metal, and the lithium source material is a lithium metal and / or a lithium-rich material.

[0143] In some embodiments, the positive electrode film layer can also optionally include a positive electrode conductive agent. The embodiments of the present application do not have special limitations on the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, the mass percentage content of the positive electrode conductive agent in the positive electrode film layer is ≤5 wt%.

[0144] In some embodiments, the positive electrode film layer can also optionally include a positive electrode binder. The embodiments of the present application do not have particular limitations on the type of positive electrode binder, and as an example, the positive electrode binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester-based resin. In some embodiments, the mass percentage content of the positive electrode binder in the positive electrode film layer is ≤ 5 wt%.

[0145] The positive electrode film layer is typically formed by coating a positive electrode slurry on a positive electrode current collector, drying, and cold-pressing. The positive electrode slurry is typically formed by dispersing and uniformly stirring a positive electrode active material, an optional conductive agent, an optional binder, and any other components in a solvent. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0146] 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 disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0147] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0148] As an example, the negative electrode current collector can adopt a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver surface-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, a carbon electrode, a carbon, nickel, or titanium, etc. can be used. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. 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, etc.) on a polymer material base material (such as a base material of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.).

[0149] As an example, the negative active material can employ a negative active material known in the art for use in the cylindrical battery cell 7. As an example, the negative active material can include at least one of: a carbon material (e.g., 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, etc. 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.

[0150] In some embodiments, the negative active material includes a silicon element, which can be in the form of a silicon-based material, e.g., 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.

[0151] 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 metal shell 20 of the cylindrical structure can constrain the expanded electrode assembly 10, so that the force of the electrode assembly 10 on the metal shell 20 is dispersed more evenly, and the metal shell 20 is less likely to deform, thereby improving the structural stability of the metal shell 20 and the use reliability of the cylindrical battery cell 7.

[0152] In the embodiments of the present application, the mass content of the silicon element in the negative electrode film layer is the meaning known in the art, which can be detected by using devices and methods known in the art, e.g., the negative electrode sheet is placed in a solvent such as water for soaking, the negative active material is separated from the negative current collector, the negative active material is obtained by suction filtration, and the content of the silicon element is obtained by using an inductively coupled plasma-emission spectrometer of ICAP7400 model of Thermo Fisher Scientific Company, USA, and referring to the GB / T30902-2014 standard.

[0153] In some embodiments, the negative electrode film layer can also optionally include a negative conductive agent. The embodiments of the present application do not have special limitations on the type of negative conductive agent. As an example, the negative conductive agent can include 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 conductive agent in the negative electrode film layer is ≤5wt%.

[0154] In some embodiments, the negative electrode film layer further optionally 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 ≤5%.

[0155] In some embodiments, the negative electrode film layer further optionally comprises other auxiliary agents. As an example, the other auxiliary agents can comprise thickening agents, such as 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%.

[0156] 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.

[0157] 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.

[0158] 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.

[0159] In some embodiments, the material of the separator film can comprise one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, without special restrictions. When the separator film is a multi-layer composite film, the materials of the respective layers can be the same or different, without special restrictions.

[0160] In some embodiments, the separator film can comprise a porous base film and a coating layer provided on at least one side of the porous base film, and the coating layer can comprise at least one of inorganic particles or organic particles.

[0161] The porous base film can comprise one or more of polyethylene and polypropylene.

[0162] The inorganic particles have good heat resistance and can improve the overall heat resistance of the separator film. The inorganic particles are substantially not subject to oxidation and reduction reactions with metal dendrites within the operating voltage range of the sodium ion battery, in other words, the inorganic particles are configured to not undergo oxidation and reduction reactions with alkali metals and / or alkaline earth metals at the nominal voltage of the sodium ion battery.

[0163] 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.

[0164] 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, copolymer of butyl acrylate and ethyl methacrylate, and mixtures thereof.

[0165] In some embodiments, the cylindrical battery cell 7 further includes an electrolyte.

[0166] During the charging and discharging of the battery cell, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting the active ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not particularly limited in the embodiments of the present application and can be selected according to actual needs.

[0167] The electrolyte includes an electrolyte salt and a solvent. The types of the electrolyte salt and the solvent are not particularly limited and can be selected according to actual needs.

[0168] In some embodiments, the electrolyte can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, can also include a positive electrode film-forming additive, and can also include 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, etc.

[0169] For example, the additive includes at least one of a cyclic carbonate compound containing an unsaturated bond, a sulfate compound, a sulfite compound, a sulfonolactone 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.

[0170] 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 into a wound structure.

[0171] As an example, a plurality of positive electrode tabs and a plurality of negative electrode tabs can be provided, respectively, and the plurality of positive electrode tabs and the plurality of negative electrode tabs are alternately stacked.

[0172] In some embodiments, the metal case 20 includes a case 21 having an opening and an end cap 22 for covering the opening.

[0173] The case 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 formed can be used to accommodate the electrode assembly 10, the electrolyte, and other components.

[0174] The case 21 and the end cap 22 can be independent components. As an example, the case 21 can be provided with an opening, and the end cap 22 is used to cover the opening to form the internal cavity of the cylindrical battery cell 7.

[0175] The end cap 22 is connected to the case 21 by welding, bonding, clamping, or other means.

[0176] The case 21 can be open at one end or at both ends. In some examples, the case 21 can be a structure open at one side, and the end cap 22 is provided as one and covers the case 21. In other examples, the case 21 can also be a structure open at both sides, and the end cap 22 is provided as two, and the two end caps 22 cover the two openings of the case 21, respectively.

[0177] In some embodiments, the case 21 includes a side wall 212 and an end wall 211 connected to the side wall 212, the end wall 211 and the end cap 22 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.

[0178] In some embodiments, the end wall 211 and the side wall 212 can have the same polarity.

[0179] In some embodiments, the end wall 211 and the side wall 212 can be an integrally formed structure, i.e., the case 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.

[0180] From the appearance of the electrode assembly 10, the electrode assembly 10 includes a main body portion 12, a first tab 111 and a second tab 112, the first tab 111 and the second tab 112 having opposite polarities, and the first tab 111 and the second tab 112 protruding from the main body portion 12, respectively. The first tab 111 is a portion of the first tab not coated with the active material layer, and the second tab 112 is a portion of the second tab not coated with the active material layer. The first tab 111 and the second tab 112 are used to lead out the current in the main body portion 12. The first tab and the second tab have opposite polarities, 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.

[0181] The first tab 111 is taken as a negative electrode tab, and the second tab 112 is taken as a positive electrode tab. The portion of the negative electrode current collector of the negative electrode tab not coated with the active material layer is a negative electrode tab, the active material coated by the negative electrode current collector of 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 portion 12. The portion of the positive electrode current collector of the positive electrode tab not coated with the active material layer is a positive electrode tab, the active material coated by the positive electrode current collector of 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 portion 12.

[0182] In some embodiments, the cylindrical battery cell 7 includes a first electrode lead-out portion and a second electrode lead-out portion, the first electrode lead-out portion being electrically connected to the first tab 111, and the second electrode lead-out portion being electrically connected to the second tab 112.

[0183] In the axial direction of the main body portion 12, the first electrode lead-out portion and the second electrode lead-out portion can also be located on both sides of the electrode assembly 10, or the first electrode lead-out portion and the second electrode lead-out portion are located on the same side of the electrode assembly 10, for example, the second electrode lead-out portion includes an electrode terminal 30 arranged in the end wall 211 in an insulating manner, and the first electrode lead-out portion is the end wall 211.

[0184] The first tab 111 and the second tab 112 can protrude from the same side of the main body portion 12, or can extend from opposite sides, respectively.

[0185] The first tab 111 and the second tab 112 can be arranged on both sides of the main body portion 12 in the axial direction, in other words, the first tab 111 and the second tab 112 are arranged at both ends of the electrode assembly 10 in the axial direction, respectively.

[0186] Optionally, the first tab 111 is wound around the central axis of the electrode assembly 10 in multiple turns, and the first tab 111 includes multiple tab layers. After winding, the first tab 111 is generally cylindrical, and a gap is left between adjacent tab layers. In the embodiments of the present application, the first tab 111 can be processed to reduce the gap between the tab layers and facilitate the connection of the first tab 111 to other conductive structures. For example, the first tab 111 can be subjected to a flattening process to gather the end of the first tab 111 away from the main body 12 together. The flattening process forms a dense end face at the end of the first tab 111 away from the main body 12, reduces the gap between the tab layers, and facilitates the connection of the first tab 111 to other conductive structures. Alternatively, the embodiments of the present application can also fill conductive material between adjacent tab layers to reduce the gap between the tab layers.

[0187] Optionally, the second tab 112 is wound around the central axis of the electrode assembly 10 in multiple turns, and the second tab 112 includes multiple tab layers. For example, the second tab 112 can also be subjected to a flattening process to reduce the gap between the tab layers of the second tab 112.

[0188] 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.

[0189] The second tab 112 is electrically connected to the electrode terminal 30 of the cylindrical battery cell 7, and the electrode terminal 30 is insulated from the end wall 211. The second tab 112 can be directly electrically connected to the electrode terminal 30, or indirectly electrically connected to the electrode terminal 30 through other conductive structures.

[0190] 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 (such as the current collecting member 40) to achieve electrical connection between the second tab 112 and the electrode terminal 30.

[0191] The electrode terminal 30 is insulated from 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.

[0192] The end wall 211 can be provided with an electrode lead-out hole, and the electrode terminal 30 is insulated from the end wall 211 and is installed in the electrode lead-out hole. The electrode lead-out hole facilitates the lead-out of the electrical energy of the electrode assembly 10 to the outside of the shell 21.

[0193] The central axis of the electrode assembly 10 is a virtual straight line. The central axis of the electrode assembly 10 can pass through the electrode lead-out hole or be offset from the electrode lead-out hole. This application does not limit this.

[0194] The electrode terminal 30 can be fixed to the end wall 211. The electrode terminal 30 can be fixed as a whole to the outside of the end wall 211, or it can extend into the interior of the metal housing 20 through the electrode lead-out hole.

[0195] When the first tab 111 is the negative tab and the second tab 112 is the positive tab, the end wall 211 is the negative output terminal of the cylindrical battery cell 7, and the electrode terminal 30 is the positive output terminal of the cylindrical battery cell 7.

[0196] In some embodiments, the cylindrical battery cell 7 includes a metal casing and an electrolyte, the electrolyte being contained within the metal casing, and the electrolyte including an electrolyte salt, which includes hexafluorophosphate and sulfonamide salt, wherein the molar concentration of hexafluorophosphate is less than or equal to 0.9 mol / L.

[0197] Hexafluorophosphates may include one or more of lithium hexafluorophosphate, sodium hexafluorophosphate, etc. Sulfonamide salts may include one or more of lithium sulfonamide and sodium sulfonamide, etc.

[0198] Hexafluorophosphate has good solubility and high conductivity in organic solvents, which gives the battery cells good kinetic performance. Moreover, hexafluorophosphate can form an excellent solid electrolyte interphase (SEI) film on the surface of the negative electrode film, which provides excellent protection for the negative electrode film.

[0199] The combined use of hexafluorophosphate and sulfonamide salt results in relatively high thermal stability of the electrolyte system. Furthermore, the relatively low molar concentration of hexafluorophosphate reduces its corrosive effect on the metal casing 20, thereby lowering the risk of corrosion and the generation of metal ions from metal corrosion within the casing 20. Additionally, the metal casing 20 of the cylindrical battery cell 7 effectively disperses forces within the system, ensuring uniform stress distribution and reducing the likelihood of deformation. This contributes to improved reliability and cycle performance of the cylindrical battery cell 7.

[0200] In some embodiments, the molar concentration of hexafluorophosphate is from 0.2 mol / L to 0.8 mol / L, optionally from 0.3 mol / L to 0.7 mol / L. A molar concentration of hexafluorophosphate within the above range can further reduce the corrosive effect on the metal casing 20, and improve the reliability and cycle performance of the cylindrical battery cell 7.

[0201] 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, or a range formed by any two of the above values.

[0202] In some embodiments, the electrolyte salt further comprises a sulfonimide salt, and the ratio of the molar concentration of the sulfonimide 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 sulfonimide 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; and 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.

[0203] Exemplarily, the ratio of the molar concentration of the sulfonimide 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.

[0204] 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, improve the use reliability and cycle performance of the battery cell, etc.; and it is also beneficial to improve the liquid-phase transport capacity of the active ion, thereby improving the kinetic performance of the battery cell.

[0205] Exemplarily, 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.

[0206] In some embodiments, the metal shell 20 comprises a shell body and a film layer, the film layer is arranged at least on the surface of the shell body facing the electrolyte, and the base element of the film layer is a nickel element. In the embodiments of the present application, the base element refers to the element with the largest proportion in the film layer.

[0207] 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 also comprises hexafluorophosphate, 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 metal shell 20, and thus improve the use reliability and cycle performance of the cylindrical battery monomer 7.

[0208] In some embodiments, the thickness of the film layer is 1.5 μm to 6.0 μm, which can be 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 7.

[0209] 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 formed by any two of the above values.

[0210] In some embodiments, when the molar concentration of hexafluorophosphate 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 hexafluorophosphate and the thickness of the film layer cooperate to improve the use reliability and cycle performance of the cylindrical battery monomer 7.

[0211] In some embodiments, when the molar concentration of hexafluorophosphate is 0.3 mol / L to 0.7 mol / L, the thickness of the film layer is 2.0 μm to 4.0 μm. The molar concentration of hexafluorophosphate and the thickness of the film layer cooperate to improve the use reliability and cycle performance of the cylindrical battery monomer 7.

[0212] In some embodiments, the mass percentage of nickel in the film layer is 70 wt% to 100 wt%, optionally 80 wt% to 95 wt%. When the mass percentage of nickel is within the above range, the corrosion resistance of the film layer is improved, thereby enhancing the reliability and cycle performance of the cylindrical battery cell 7.

[0213] For example, the mass percentage of nickel in the film layer can be 70wt%, 71wt%, 72wt%, 73wt%, 74wt%, 75wt%, 76wt%, 80wt%, 82wt%, 85wt%, 88wt%, 90wt%, 92wt%, 95wt%, 98wt%, 99wt%, 100wt%, or any range of two of the above values.

[0214] In some embodiments, when the molar concentration of hexafluorophosphate is from 0.2 mol / L to 0.8 mol / L, the mass percentage of nickel in the film layer is from 70 wt% to 100 wt%. The combination of the molar concentration of hexafluorophosphate and the mass percentage of nickel in the film layer can improve both the reliability and cycle performance of the cylindrical battery cell 7.

[0215] In some embodiments, when the molar concentration of hexafluorophosphate is from 0.3 mol / L to 0.7 mol / L, the mass percentage of nickel in the film layer is from 80 wt% to 95 wt%. The combination of the molar concentration of hexafluorophosphate and the mass percentage of nickel in the film layer can improve both the reliability and cycle performance of the cylindrical battery cell 7.

[0216] Nickel can exist in the film layer in the form of elemental nickel or nickel alloy. Nickel alloy can be an alloy with nickel as the base element and iron and carbon as auxiliary elements.

[0217] In some embodiments, the film layer further includes iron, with the iron content in the film layer ranging from 0.1 wt% to 10 wt%, optionally from 1 wt% to 5 wt%. When the iron content is within the above range, it can effectively improve the conductivity of the metal casing 20, which is beneficial for electron transport.

[0218] For example, the mass percentage of iron 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 any range of two of the above values.

[0219] In some embodiments, the film layer further comprises carbon elements, and the mass percentage of the carbon elements in the film layer is 0.1wt% to 15wt%, or optionally 4wt% to 12wt%. 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.

[0220] For example, the mass percentage of the carbon elements 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.

[0221] In some embodiments, when the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, the thickness of the film layer is 1.5μm to 6.0μm. The electrolyte 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, when the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2, the thickness of the film layer is 2.0μm to 4.0μm. The electrolyte salt and the thickness of the film layer cooperate to improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0223] In some embodiments, when the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6, the mass percentage of the nickel element is 70wt% to 100wt%. The electrolyte salt and the mass percentage of the nickel element cooperate to improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0224] In some embodiments, when the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2, the mass percentage of the nickel element is 80wt% to 95wt%. The electrolyte salt and the mass percentage of the nickel element cooperate to improve the use reliability and cycle performance of the cylindrical battery cell 7.

[0225] In some embodiments, when the ratio of the molar concentration of the sulfonimide salt to the molar concentration of the hexafluorophosphate salt is 0.3 to 1.5, the layered transition metal oxide comprises a chemical formula of Li a Ni b Co c M d Oe A f At least one of the compounds and their modified compounds, 0.3 ≤ b < 1, optionally 0.5 ≤ b < 1, and further optionally 0.75 ≤ b ≤ 0.98. The relatively high mass percentage of nickel makes the interfacial properties between the layered transition metal oxide and the electrolyte more reactive. When the ratio of the molar concentration of sulfonyl imide salt to the molar concentration of hexafluorophosphate is within the above range, the sulfonyl imide salt can improve the interfacial stability between 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.

[0226] 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 of any two of the above values.

[0227] In some embodiments, sulfonamide salts include anions represented by formula A.

[0228] In formula A, R1 and R2 each independently include a halogen atom or a C1 to C6 haloalkyl group.

[0229] The sulfonyl imide salt of the above-mentioned material has excellent thermal stability, which helps to reduce the corrosion of the metal casing 20 by the electrolyte salt and improve the reliability and cycle performance of the cylindrical battery cell 7.

[0230] In some embodiments, the halogen atom includes a fluorine atom.

[0231] In some embodiments, C1 to C6 haloalkyl groups include C1 to C6 fluoroalkyl groups.

[0232] In some embodiments, R1 and R2 each independently comprise fluorine atoms or C1 to C3 fluoroalkyl groups. The aforementioned materials readily dissociate into active ions, and the electrolyte salt has a relatively low viscosity, which is beneficial for improving the liquid phase transport capability of the electrolyte and enhancing its kinetic properties.

[0233] For example, the anion represented by formula A includes one or more of the anions represented by formulas A-1 to A-5.

[0234] Optionally, the anion represented by formula A includes one or more of the anions represented by formulas A-1 to A-2.

[0235] The film layer can protect the shell body. The shell body can be made of various materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the shell body is made of steel, such as stainless steel, which has excellent mechanical strength and is not easy to deform, thereby further improving the use reliability of the cylindrical battery cell 7. In the embodiments of the present application, the base material is the material with the largest proportion. Of course, the shell body can also be made of steel.

[0236] The metal shell 20 includes a shell body and an end cover 22. The shell body can include a shell body, in which case the shell body 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; and the shell body and the end cover 22 both include a shell body.

[0237] 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 25.5 wt%.

[0238] In some embodiments, the cylindrical battery cell 7 includes a metal shell 20, an electrode assembly 10, and an electrolyte, the metal shell 20 containing the electrode assembly 10 and the electrolyte, wherein the metal shell 20 is in 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 25.5 wt%.

[0239] The mass percentage of the chain ester solvent is greater than or equal to 25.5 wt%, which makes the electrolyte have a relatively high conductivity, thereby improving the liquid-phase transmission capacity of active ions and the rapid charging and discharging capacity of the cylindrical battery cell 7, and thus improving the rate performance of the cylindrical battery cell 7. However, such a solvent may face decomposition and gas production during the cyclic charging and discharging of the cylindrical battery cell 7. However, the metal shell 20 of the cylindrical battery cell 7 is in a cylindrical structure, which can uniformly disperse the pressure inside the cylindrical battery cell 7, thereby uniformly distributing the stress on the metal shell 20 and effectively increasing the pressure resistance of the metal shell 20, and thus improving the use reliability of the cylindrical battery cell 7.

[0240] On the other hand, the electrode assembly 10 is subjected to extrusion and backflow of the electrolyte during the cyclic charging and discharging. However, due to the cylindrical structure of the metal shell 20, the axial dimension of the cylindrical battery cell 7 can be much larger than the radial dimension, which makes the backflow path of the electrolyte in the axial direction relatively long and not easy to fully soak the electrode assembly 10. In the embodiments of the present application, the electrolyte uses a chain ester solvent, and the mass percentage of the chain ester solvent is greater than or equal to 25.5 wt%, which makes the viscosity of the electrolyte system relatively low and more easily flow to soak the electrode assembly 10, thereby improving the rapid charging and discharging capacity of the cylindrical battery cell 7 and further improving the rate performance of the cylindrical battery cell 7.

[0241] Therefore, the embodiments of the present application can improve the rate performance and reliability of the cylindrical battery cell 7 by using the specific electrolyte system and the cylindrical metal shell 20.

[0242] In some embodiments, the mass percentage of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%, optionally 25.5wt% to 70wt%, and further optionally 42.5wt% to 70wt%. When the mass percentage of the chain ester solvent is within the above range, the rate performance and reliability of the battery cell 7 can be further improved, and the cycle performance of the battery cell 7 can be further improved.

[0243] 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 formed by any two of the above values.

[0244] 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 reliability of the cylindrical battery cell 7.

[0245] In some embodiments, the mass percentage of the chain carbonate in the electrolyte is 4wt% to 70wt%, optionally 4wt% to 42.5wt%, and further optionally 8.5wt% to 35wt%. When the mass percentage of the chain carbonate is within 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 reliability of the battery cell 7 can be further improved, and the cycle performance of the battery cell 7 can be further improved.

[0246] 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 formed by any two of the above values.

[0247] In some embodiments, the chain carbonate includes a compound shown in Formula I,

[0248] In Formula I, R 11 and R 12 each independently includes C1 to C3 alkyl or C1 to C3 haloalkyl. When the chain carbonate is 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.

[0249] In some embodiments, R 11 and R 12 each independently includes C1 to C3 alkyl or C1 to C3 haloalkyl.

[0250] For example, the chain carbonate includes one or more of a compound shown in Formula I-1 to a compound shown in Formula I-6,

[0251] Optionally, the chain carbonate includes a compound shown in Formula I-1,

[0252] For example, the chain carbonate includes a compound shown in Formula I-1, and the mass percentage content of the compound shown in Formula I-1 in the electrolyte is 4wt% to 42.5wt%, optionally 8.5wt% to 35wt%.

[0253] In some embodiments, the chain ester solvent also 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.

[0254] In some embodiments, the mass percentage content of the chain carboxylic acid ester in the electrolyte is 4wt% to 70wt%, optionally 8.5wt% to 60wt%, and optionally 20wt% to 55wt%. When the mass percentage content of the chain carboxylic acid ester in the electrolyte 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, and the rate performance and use reliability of the battery cell 7 can be further improved.

[0255] Exemplarily, the mass percentage content of the chain carboxylic acid 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.

[0256] In some embodiments, the chain carboxylic acid ester comprises a compound of Formula II,

[0257] In Formula II,

[0258] R 21 comprises a hydrogen atom, a halogen atom, a C1-C3 alkyl group, or a C1-C3 haloalkyl group;

[0259] R 22 comprises a C1-C3 alkyl group or a C1-C3 haloalkyl group.

[0260] In some embodiments, R 21 comprises a hydrogen atom, a fluorine atom, a C1-C3 alkyl group, or a C1-C3 fluoroalkyl group.

[0261] In some embodiments, R 22 comprises a C1-C3 alkyl group or a C1-C3 fluoroalkyl group.

[0262] Exemplarily, the chain carboxylic acid ester comprises one or more of a compound of Formula II-1 to a compound of Formula II-6,

[0263] Alternatively, exemplarily, the chain carboxylic acid ester comprises one or more of a compound of Formula II-1 to a compound of Formula II-6,

[0264] The chain carboxylic acid ester can comprise various options,

[0265] For example, the chain carboxylic acid ester comprises a compound of Formula II-2, and the mass percentage content of the compound of Formula II-2 in the electrolyte is 20wt% to 55wt%.

[0266] For another example, the chain carboxylic acid ester comprises a compound of Formula II-3, and the mass percentage content of the compound of Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0267] For another example, 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%.

[0268] For example, the chain ester solvent of the electrolyte can include the compound shown in Formula I-1 and the compound shown in Formula II-2, and the mass percentage of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%, optionally 25.5wt% to 70wt%; optionally 42.5wt% to 70wt%; for example, the mass percentage of the compound shown in Formula I-1 in the electrolyte is 8.5wt% to 35wt%, and the mass percentage of the compound shown in Formula II-2 in the electrolyte is 20wt% to 55wt%.

[0269] For example, the chain ester solvent of the electrolyte can include the compound shown in Formula I-1 and the compound shown in Formula II-3, and the mass percentage of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%, optionally 25.5wt% to 70wt%; optionally 42.5wt% to 70wt%; for example, the mass percentage of the compound shown in Formula I-1 in the electrolyte is 8.5wt% to 35wt%, and the mass percentage of the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0270] For example, the chain ester solvent of the electrolyte can include the compound shown in Formula I-1 and the compound shown in Formula II-3, and the mass percentage of the chain ester solvent in the electrolyte is 25.5wt% to 76.5wt%, optionally 25.5wt% to 70wt%; optionally 42.5wt% to 70wt%; for example, the mass percentage of the compound shown in Formula I-1 in the electrolyte is 8.5wt% to 35wt%, and the mass percentage of the compound shown in Formula II-3 in the electrolyte is 20wt% to 55wt%.

[0271] The metal shell 20 is in a cylindrical structure, and the metal shell 20 includes a shell body 21 which can also be in a cylindrical structure corresponding to the shape of the electrode assembly 10. The material of the metal shell 20 can be various, for example, the base material of the metal shell 20 includes but is not limited to copper, iron, aluminum, steel, aluminum alloy, etc. Optionally, the base material of the metal shell 20 includes steel, for example, stainless steel. Exemplarily, the base material of the shell body 21 includes steel, for example, stainless steel. The end cover 22 can have a shape corresponding to that of the shell body 21 to fit the shell body 21. The base material of the end cover 22 can be the same as or different from that of the shell body 21. Optionally, the end cover 22 can be made of a material (such as copper, iron, aluminum, steel, aluminum alloy, plastic, etc.) having certain hardness and strength, so that the end cover 22 is not easy to deform when subjected to extrusion and collision, and the cylindrical battery monomer 7 can have higher structural strength and improved reliability. Optionally, the base material of the end cover 22 can include steel, for example, stainless steel. In the embodiments of the present application, the base material is the material with the largest proportion.

[0272] In some embodiments, the metal shell 20 includes the shell body 21 and the 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 metal shell 20.

[0273] In some embodiments, the side wall 212 and the end wall 211 are integrally formed.

[0274] In some embodiments, the base material of the side wall 212 includes steel, and the thickness of the side wall 212 is 0.30-1.2 mm, which can be 0.30-0.55 mm. When the thickness of the side wall 212 is in the above range, the side wall 212 has higher strength and stronger ability to withstand pressure, which can effectively reduce the risk of deformation of the side wall 212 and the risk of bulging of the cylindrical battery monomer 7, thereby improving the use reliability of the cylindrical battery monomer 7.

[0275] Exemplarily, the thickness of the side wall 212 can be 0.30 mm, 0.31 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.45 mm, 0.48 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, 1.5 mm, or a range formed by any two of the above values.

[0276] 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 metal shell 20 is in the above range, the metal shell 20 has a higher strength and a stronger ability to withstand pressure, which can effectively alleviate the risk of deformation of the metal 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.

[0277] 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 metal 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.

[0278] 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.

[0279] As shown in FIGS. 6 and 7, in some embodiments, the metal shell 20 includes a shell body 21 and an end cover 22. The shell body 21 has an opening, and the end cover 22 is connected to the shell body 21 and covers the opening. The end cover 22 is provided with a pressure relief mechanism 220.

[0280] 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 metal shell 20 reaches a threshold value, so that the internal space of the metal shell 20 communicates with the external space to release the pressure or temperature in the metal 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.

[0281] In embodiments of the present application, the deformation of the pressure relief mechanism 220 can be triggered by the internal pressure of the metal shell 20, or by the internal temperature of the metal shell 20, or by both the internal pressure and the internal temperature of the metal shell 20.

[0282] As an example, as the gas inside the metal shell 20 continues to accumulate, the internal pressure of the metal shell 20 can reach or even exceed a pressure threshold. In the case where the internal pressure of the metal shell 20 reaches the threshold, the pressure relief mechanism 220 deforms under the action of the internal pressure to communicate the internal space of the metal shell 20 with the external space, and the gas inside the metal shell 20 can be discharged, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0283] As an example, when the electrolyte and the active material react and release heat rapidly, the internal temperature of the metal shell 20 can rise, and the temperature rise can also cause the internal pressure of the metal shell 20 to rise. In the case where the internal temperature of the metal shell 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 metal shell 20 with the external space, and the gas inside the metal shell 20 can be discharged, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0284] In the case where the internal pressure or the temperature of the metal shell 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 metal shell 20 with the external space, and then discharge the internal gas and the internal pressure of the metal shell 20, thereby reducing the risk of explosion of the cylindrical battery cell 7.

[0285] 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.

[0286] 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 part, in this way, the cylindrical battery cell 7 can be depressurized under controllable pressure, thereby avoiding potential more serious accidents.

[0287] 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.

[0288] 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.

[0289] 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.

[0290] 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 metal 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.

[0291] 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).

[0292] 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.

[0293] 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.

[0294] 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.

[0295] 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.

[0296] 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.

[0297] 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.

[0298] Embodiments

[0299] 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.

[0300] Example 1

[0301] 1. Preparation of positive electrode sheet

[0302] The positive electrode sheet comprises 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 comprises positive active material, conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) in a weight ratio of 96.5:2:1.5.

[0303] The positive active material comprises a compound with a molecular formula of LiNi 0.9 Co 0.05 Mn 0.05 O2(Ni90).

[0304] 2. Preparation of negative electrode sheet

[0305] The negative electrode sheet comprises 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 comprises 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.

[0306] The negative active material comprises artificial graphite and silicon-based material (specifically silicon-carbon compound), and the content of silicon element in the negative film layer is 5%.

[0307] 3. Isolation film

[0308] The isolation film is a polypropylene (PP) film layer.

[0309] 4. Preparation of electrolyte

[0310] 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.

[0311] 5. Preparation of a cylindrical battery monomer

[0312] The positive electrode sheet, the separator and the negative electrode sheet are stacked in sequence with the separator between the positive electrode sheet and the negative electrode sheet to play a separating role, the positive electrode sheet, the separator and the negative electrode sheet are wound to obtain an electrode assembly; the electrode assembly is placed 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 is arranged around 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 located 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.

[0313] Comparative Example 1

[0314] The cylindrical battery monomer is prepared by using a method similar to that of Example 1, except that the lithium salt comprises 1.0 mol / L of lithium hexafluorophosphate LiPF6; and the side wall does not comprise a film layer.

[0315] Examples 2-1 to 2-10

[0316] 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.

[0317] In Examples 2-1 to 2-9, the shell comprises a shell body and a film layer; in Example 2-10, the side wall does not comprise a film layer.

[0318] Examples 3-1 and 3-2

[0319] 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.

[0320] Performance test

[0321] 1. Cycle performance test of battery cell

[0322] The cylindrical battery cell prepared in each example and comparative example was charged at 45°C at a constant current of 0.5C rate 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, and then rested for 5 min, and then discharged at a constant current of 0.33C rate to a discharge cut-off voltage of 2.5V, and then rested for 5 min, which was one charge-discharge cycle. The capacity retention rate of the battery cell after 800 cycles was calculated according to the above cycle charge-discharge test of the battery cell.

[0323] 2. Gas production test of battery storage

[0324] The cylindrical battery cell prepared in each example and comparative example was charged at 25°C at a constant current of 0.5C rate 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.

[0325] 3. Internal resistance test of battery cell

[0326] The cylindrical battery cell prepared in each example and comparative example was charged at 25°C at a constant current of 1C rate 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).

[0327] The positive and negative pens of the TH2523A alternating current 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.

[0328] Test results

[0329] The test results are shown in Table 1.

[0330] Table 1

[0331] In Table 1,

[0332] Formula A-1 represents a bis-fluorosulfonylimide ion, and the corresponding cation is a lithium ion,

[0333] Formula A-2 represents a bis-trifluoromethanesulfonylimide ion, and the corresponding cation is a lithium ion,

[0334] Formula A-3 represents a (fluorosulfonyl)(trifluoromethanesulfonyl)imido ion, and the corresponding cation is a lithium ion.

[0335] As can be seen from Table 1,

[0336] The molar concentration of lithium hexafluorophosphate in Comparative Example 1 is relatively high, which is easy to cause corrosion to the shell; compared with Comparative Example 1, the molar concentration of lithium hexafluorophosphate in the present application is reduced, which can effectively reduce the hydrogen fluoride generated by the decomposition of lithium hexafluorophosphate, thereby alleviating the corrosion to the shell, improving the cycle performance of the cylindrical battery monomer, and reducing the internal pressure of the cylindrical battery monomer, reducing the gas production, and improving the use reliability of the cylindrical battery monomer.

[0337] Examples 2-1 to 2-10 can further improve the cycle performance of the cylindrical battery monomer by adjusting the composition of the lithium salt, and can further reduce the internal pressure of the cylindrical battery monomer, reduce the gas production, improve the use reliability of the cylindrical battery monomer, and 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 by adjusting the composition of the sulfonimide salt, and can further reduce the internal pressure of the cylindrical battery monomer, reduce the gas production, improve the use reliability of the cylindrical battery monomer, and improve the ion liquid phase transmission ability of the electrolyte system, reduce the resistance, and improve the rate performance.

[0338] Example 4

[0339] The cylindrical battery monomer was prepared by a method similar to Example 1, and the thickness of the film layer in the side wall of the shell was adjusted.

[0340] Example 5

[0341] The cylindrical battery monomer was prepared by a method similar to Example 1, and the composition of the film layer in the side wall of the shell was adjusted.

[0342] The test results are shown in Table 2.

[0343] Table 2

[0344] As can be seen from Table 2, the electrolyte system in the present application is suitable for metal shells with different film thicknesses, for example, 1.5 μm to 6.0 μm, and optionally 2.0 μm to 4.0 μm; when the film layer satisfies the above range, the battery has excellent cycle performance and use reliability.

[0345] The electrolyte system in the present application is suitable for metal shells with different film thicknesses, for example, 1.5 μm to 6.0 μm, and optionally 2.0 μm to 4.0 μm; when the film layer satisfies the above range, the battery has excellent cycle performance and use reliability.

[0346] While the illustrative embodiments have been demonstrated and described, it should be understood that the embodiments described above are not to be interpreted in a limiting sense and that changes, alternatives and modifications can be made to the embodiments without departing from the spirit, principles and scope of the application.

[0347] While the illustrative embodiments have been demonstrated and described, it should be understood that the embodiments described above are not to be interpreted in a limiting sense and that changes, alternatives and modifications can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims

1. A cylindrical battery cell, comprising: a metal case; and an electrolyte solution contained in the metal case, the electrolyte solution comprising electrolyte salts, the electrolyte salts comprising a hexafluorophosphate salt and a sulfimide salt, the hexafluorophosphate salt having a molar concentration of 0.9 mol / L or less. The hexafluorophosphate salt has a molar concentration of 0.2 mol / L to 0.8 mol / L.

2. The cylindrical battery cell of claim 1, wherein, The hexafluorophosphate salt has a molar concentration of 0.3 mol / L to 0.7 mol / L.

3. The cylindrical battery cell of claim 2, wherein, The ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.06 to 6.

4. The cylindrical battery cell according to any one of claims 1 to 3, wherein, The ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.2 to 2.

5. The cylindrical battery cell of claim 4, wherein, The ratio of the molar concentration of the sulfimide salt to the molar concentration of the hexafluorophosphate salt is 0.3 to 1.

5.

6. The cylindrical battery cell of claim 5, wherein, The electrolyte salts have a molar concentration of 0.5 mol / L to 2 mol / L.

7. The cylindrical battery cell according to any one of claims 1 to 6, wherein, The electrolyte salts have a molar concentration of 0.6 mol / L to 1.5 mol / L.

8. The cylindrical battery cell of claim 7, wherein, The metal case comprises a case body and a film layer, the film layer being provided at least on a surface of the case body facing the electrolyte solution, the film layer having a base element of nickel.

9. The cylindrical battery cell according to any one of claims 1 to 8, wherein, The film layer has a thickness of 1.5 μm to 6.0 μm.

10. The cylindrical battery cell of claim 9, wherein, The film layer has a thickness of 2.0 μm to 4.0 μm.

11. The cylindrical battery cell of claim 10, wherein, The mass percentage of the nickel element in the film layer is 70 wt% to 100 wt%.

12. The cylindrical battery cell of any one of claims 9-11, wherein, The mass percentage of the nickel element in the film layer is 80 wt% to 95 wt%.

13. The cylindrical battery cell of claim 12, 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 14. The cylindrical battery cell of any one of claims 9 to 13, 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%. The mass percentage of the iron element in the film layer is 1 wt% to 5 wt%.

15. The cylindrical battery cell of claim 14, wherein, The mass percentage of the carbon element in the film layer is 4 wt% to 12 wt%.

16. The cylindrical battery cell of claim 14 or 15, wherein, The base material of the case body is steel.

17. The cylindrical battery cell of any one of claims 9 to 16, wherein, In formula A, R1 and R2 each independently comprise a halogen atom or a C1 to C6 halogenated alkyl group.

18. The cylindrical battery cell of any one of claims 1 to 17, wherein, The sulfonimide salt includes an anion represented by Formula A, The halogen atom comprises a fluorine atom; and / or 19. The cylindrical battery cell of claim 18, wherein, The C1 to C6 halogenated alkyl group comprises a C1 to C6 fluorinated alkyl group. R1 and R2 each independently comprise a fluorine atom or a C1 to C3 fluorinated alkyl group.

20. The cylindrical battery cell of claim 19, wherein, 23.The cylindrical battery cell according to any one of claims 1 to 22, comprising an electrode assembly, the electrode assembly comprising a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer provided on at least one side of the positive electrode current collector, the positive electrode film layer comprising a positive electrode active material, the positive electrode active material comprising a layered transition metal oxide.

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, The electrolyte solution comprises a chain ester solvent, the chain ester solvent having a mass percentage of 25.5 wt% or more in the electrolyte solution.

24. The cylindrical battery cell of claim 23, wherein, The layered transition metal oxide includes at least one of a compound of a chemical formula of Li a Ni b Co c M d O e A f a compound modified therefrom, 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.

25. The cylindrical battery cell of any one of claims 1 to 24, wherein, The chain ester solvent has a mass percentage of 25.5 wt% to 76.5 wt% in the electrolyte solution.

26. The cylindrical battery cell of claim 25, wherein, The chain ester solvent comprises a chain carbonate, the chain carbonate having a mass percentage of 4 wt% to 70 wt% in the electrolyte solution.

27. The cylindrical battery cell of claim 25 or 26, wherein, ​ 28. The cylindrical battery cell of claim 27, 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.

29. The cylindrical battery cell of claim 28, wherein, R 11 and R 12 each independently comprises a C1to C3alkyl group or a C1to C3fluoroalkyl group.

30. The cylindrical battery cell of claim 28 or 29, wherein, The chain carbonate includes one or more of compounds represented by Formula I-1 to Formula I-6, 31. The cylindrical battery cell of claim 30, wherein, The chain carbonate includes a compound represented by Formula I-1, 32. The cylindrical battery cell of any one of claims 25-31, wherein, The chain ester solvent further includes a chain carboxylic acid ester having a mass percentage content of 4 wt% to 70 wt% in the electrolyte.

33. The cylindrical battery cell of claim 32, wherein, The chain carboxylic acid ester has a mass percentage content of 8.5 wt% to 60 wt% in the electrolyte.

34. The cylindrical battery cell of claim 32 or 33, 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.

35. The cylindrical battery cell of claim 34, 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.

36. The cylindrical battery cell of claim 34 or 35, wherein, The chain carboxylate includes one or more of a compound represented by Formula II-1 to a compound represented by Formula II-6, 37. The cylindrical battery cell of claim 36, 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.

38. The cylindrical battery cell of claim 37, wherein, The chain carbonate includes a compound represented by Formula I-1, The compound shown in formula I-1 has a mass percentage content of 8.5 wt% to 35 wt% in the electrolyte. The chain carboxylic acid ester includes a compound shown in formula II-2 and a compound shown in formula II-3, and the compound shown in formula II-2 and the compound shown in formula II-3 have a mass percentage content of 20 wt% to 55 wt% in the electrolyte.

39. The cylindrical battery cell of any one of claims 1-38, wherein, The metal 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 in the axial direction of the cylindrical battery cell.

40. The cylindrical battery cell of claim 39, wherein, The base material of the side wall is steel, and the thickness of the side wall is 0.30 mm to 1.2 mm.

41. The cylindrical battery cell of claim 39 or 40, wherein, The side wall and the end wall are integrally formed.

42. The cylindrical battery cell of any one of claims 39-41, wherein, The end cover is provided with a pressure relief mechanism.

43. The cylindrical battery cell of claim 42, 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 0.01 mm to 0.3 mm.

44. The cylindrical battery cell of claim 43, wherein, The end cover is provided with a recess, and the bottom wall of the recess is the weak portion.

45. The cylindrical battery cell of any one of claims 39 to 44, further comprising an electrode terminal disposed on the end wall. The cylindrical battery cell includes an electrode assembly accommodated in the shell body, 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.

46. The cylindrical battery cell of any one of claims 1-45, wherein, The dimension of the metal shell in the axial direction of the cylindrical battery cell is 1.3 times to 2.5 times the dimension of the metal shell in the radial direction of the cylindrical battery cell.

47. The cylindrical battery cell of any one of claims 1-46, wherein, The dimension of the metal shell in the axial direction of the cylindrical battery cell is 50 mm to 150 mm; and / or The dimension of the metal shell in the radial direction of the cylindrical battery cell is 40 mm to 80 mm.

48. A battery comprising the cylindrical battery cell of any one of claims 1 to 47.

49. An electric device comprising the battery of claim 48.

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