Battery cell, battery, and electric device

Abstract

A battery cell, a battery, and an electric device, relating to the technical field of batteries. In the battery cell, a film-forming additive capable of forming a solid electrolyte interphase (SEI) film on the surface of a negative electrode sheet during battery cycling is added to an electrolyte solution, an artificial SEI layer is provided on the negative electrode sheet, and the artificial SEI layer coordinates with the SEI film formed by the film-forming additive, reducing the reduction of the electrolyte solution on the surface of the negative electrode sheet, thereby slowing down the calendar life degradation of long-cycle secondary batteries.

Description

A battery cell, a battery, and an electrical device. Cross-referencing

[0001] This application claims priority to Chinese Patent Application No. 2024110453514, filed on July 31, 2024, entitled "A Battery Cell, a Battery and an Electrical Device", the contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and more specifically, to a battery cell, a battery, and an electrical device. Background Technology

[0003] Currently, long-cycle rechargeable batteries using graphite as the negative electrode active material exhibit high reducibility of the negative electrode under high SOC conditions, leading to a rapid decline in the overall battery calendar life. This decline is particularly accelerated at higher temperatures. Summary of the Invention

[0004] In view of the above problems, this application provides a battery cell, a battery, and an electrical device that can slow down the calendar life degradation of long-cycle secondary batteries.

[0005] In a first aspect, this application provides a battery cell, the battery cell comprising an electrolyte and a negative electrode, the electrolyte comprising a solvent, an electrolyte, and a film-forming additive; the negative electrode is at least partially immersed in the electrolyte, the negative electrode comprising a negative current collector, a negative active material layer, and an artificial solid electrolyte interfacial layer, the negative active material layer being attached to at least a portion of the surface of the negative current collector; the negative active material layer comprising a negative active material, the negative active material comprising graphite, the thermal decomposition temperature of the graphite being above 800°C, and the artificial solid electrolyte interfacial layer being disposed between the electrolyte and at least a portion of the negative active material.

[0006] In the technical solution of this application embodiment, by adding a film-forming additive that can form an SEI film on the surface of the negative electrode during battery cycling to the electrolyte, and simultaneously setting an artificial solid electrolyte interface phase layer on the negative electrode, the artificial solid electrolyte interface phase layer and the SEI film formed by the film-forming additive cooperate with each other to reduce the reduction of the electrode liquid on the surface of the negative electrode, thereby slowing down the calendar life decay of the long-cycle secondary battery.

[0007] In some embodiments, the film-forming additive includes sulfur-containing additives.

[0008] In the above implementation process, the use of sulfur-containing additives as film-forming additives can not only form an SEI film and an artificial solid electrolyte interface phase layer to slow down the calendar life decay of long-cycle secondary batteries, but also help reduce the DC internal resistance (DCR) of the entire battery cell.

[0009] In some embodiments, the sulfur-containing additive includes at least one of sulfate ester compounds, sulfite ester compounds, and sulfonyl lactone compounds.

[0010] In some embodiments, the artificial solid electrolyte interface phase layer comprises a carboxylate.

[0011] In some embodiments, the composition of the artificial solid electrolyte interface phase layer includes at least one of a lithium carboxyl-containing compound and a sodium carboxyl-containing compound.

[0012] In some embodiments, the film-forming additive accounts for 0.01% to 10% of the mass of the electrolyte; in the negative electrode sheet, the mass ratio of Li and / or Na elements to the negative electrode active material is ≤0.5%.

[0013] In the above implementation process, the amount of film-forming additive can be regarded as the thickness of the SEI film to a certain extent, and the mass ratio of Li and / or Na elements to the negative electrode active material can be regarded as the thickness of the artificial solid electrolyte interfacial layer to a certain extent. The thicker the SEI film or artificial solid electrolyte interfacial layer, the better it is to block the contact between the negative electrode sheet and the electrolyte, thus benefiting the calendar life of the battery cell. The thinner the SEI film or artificial solid electrolyte interfacial layer, the better it is to control the DC internal resistance (DCR) of the battery cell within a smaller range. The SEI film formed by the artificial solid electrolyte interfacial layer and the film-forming additive can work together to reduce the thickness of the SEI film and the thickness of the artificial solid electrolyte interfacial layer, respectively. By controlling the mass ratio of the film-forming additive in the electrolyte to 0.01% to 10% and the mass ratio of Li and / or Na elements to the negative electrode active material to ≤0.5%, the battery cell can have a good calendar life while also having a low DC internal resistance (DCR).

[0014] In some embodiments, the film-forming additive accounts for 0.1% to 5% of the mass of the electrolyte; in the negative electrode sheet, the mass ratio of Li and / or Na elements to the negative electrode active material is ≤0.2%.

[0015] In the above implementation process, the mass ratio of film-forming additives in the electrolyte is controlled to be 0.1% to 5%, and the mass ratio of Li and / or Na elements to negative electrode active materials is ≤0.2%, so that the battery cells have better calendar life, while also ensuring that the battery cells have lower DC internal resistance (DCR).

[0016] In some embodiments, the composition of the artificial solid electrolyte interface phase layer includes at least one of compounds containing double bonds, compounds containing epoxy groups, compounds containing carbonyl groups, and compounds containing amine groups.

[0017] In some embodiments, the thermal decomposition temperature of the graphite is 800°C to 830°C.

[0018] In the above implementation process, a higher thermal decomposition temperature of graphite is more beneficial to the calendar life of long-cycle batteries, while a lower thermal decomposition temperature is more conducive to obtaining graphite materials, thereby helping to control battery costs. By combining an artificial solid electrolyte interphase (SEI) layer with film-forming additives, the stability requirements of graphite in long-cycle batteries can be reduced. By controlling the thermal decomposition temperature of graphite to 800℃~830℃, a good calendar life for long-cycle batteries can be achieved at a lower cost.

[0019] In some embodiments, the thermal decomposition temperature of the graphite is ≥830°C.

[0020] In the above implementation process, the higher the thermal decomposition temperature of graphite, the better it is for the calendar life of long-cycle batteries. By controlling the thermal decomposition temperature of graphite to ≥830℃, it is beneficial to improve the calendar life of long-cycle batteries.

[0021] Secondly, this application provides a battery, which includes the battery cell provided in the first aspect.

[0022] Thirdly, this application provides an electrical device, which includes a battery cell provided in the first aspect or a battery provided in the second aspect. Attached Figure Description

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0024] Figure 1 is a schematic diagram of the vehicle structure provided in some embodiments of this application;

[0025] Figure 2 is an exploded structural diagram of a secondary battery provided in some embodiments of this application;

[0026] Figure 3 is a schematic diagram of the structure of a battery cell provided in some embodiments of this application;

[0027] Figure 4 is an exploded view of a single battery cell provided in some embodiments of this application;

[0028] Figure 5 is a schematic diagram of the first structure of the negative electrode sheet provided in some embodiments of this application;

[0029] Figure 6 is a schematic diagram of the second structure of the negative electrode sheet provided in some embodiments of this application;

[0030] Figure 7 is a flowchart of the preparation process of a battery cell provided in some embodiments of this application.

[0031] The reference numerals in the detailed embodiments are as follows:

[0032] 1000 - Vehicle; 100 - Secondary battery; 200 - Motor; 300 - Controller; 10 - Housing; 11 - Accommodation space; 12 - First part; 13 - Second part; 20 - Battery cell; 21 - Shell; 211 - Opening; 22 - End cap assembly; 221 - End cap; 222 - Electrode terminal; 23 - Electrode assembly; 231 - Negative electrode sheet; 2311 - Negative current collector; 2312 - Negative active material layer; 2313 - Artificial solid electrolyte interface layer; 24 - Current collector component; 25 - Insulation protection component. Detailed Implementation

[0033] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0035] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0036] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0037] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0038] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0039] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0040] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0041] Currently, judging from market trends, the application of power batteries is becoming increasingly widespread. Power batteries are not only used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, but also extensively used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. With the continuous expansion of power battery applications, market demand is also constantly increasing.

[0042] Power batteries can be lithium-ion batteries, sodium-ion batteries, etc. Currently, long-cycle rechargeable batteries using graphite as the negative electrode active material exhibit high reducibility of the negative electrode under high SOC conditions, leading to a rapid decline in the overall battery calendar life. This decline is particularly accelerated at higher temperatures.

[0043] Based on the above considerations, in order to mitigate the calendar life degradation of long-cycle secondary batteries, this application proposes a battery cell, which includes an electrolyte and a negative electrode. The electrolyte includes a solvent, an electrolyte, and a film-forming additive. At least a portion of the negative electrode is immersed in the electrolyte. The negative electrode includes a negative current collector, a negative active material layer, and an artificial solid electrolyte interface layer 2313. The negative active material layer is attached to at least a portion of the surface of the negative current collector. The negative active material layer includes a negative active material, which includes graphite. The thermal decomposition temperature of the graphite is above 800°C. The artificial solid electrolyte interface layer 2313 is disposed between the electrolyte and at least a portion of the negative active material.

[0044] In such a battery cell, by adding a film-forming additive to the electrolyte that can form an SEI film on the surface of the negative electrode during battery cycling, and simultaneously setting an artificial solid electrolyte interface phase layer 2313 on the negative electrode, the artificial solid electrolyte interface phase layer 2313 and the SEI film formed by the film-forming additive work together to reduce the reduction of the electrode liquid on the surface of the negative electrode, thereby slowing down the calendar life decay of the long-cycle secondary battery.

[0045] The battery cell can be used, but is not limited to, in electrical devices such as vehicles, ships, or aircraft. A power system for such an electrical device can be constructed using batteries disclosed in this application.

[0046] This application provides an electrical device that uses a battery as a power source. The electrical device can be, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0047] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0048] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A secondary battery 100 is installed inside the vehicle 1000, and the secondary battery 100 can be located at the bottom, front, or rear of the vehicle 1000. The secondary battery 100 can be used to power the vehicle 1000; for example, the secondary battery 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 300 and a motor 200. The controller 300 is used to control the secondary battery 100 to supply power to the motor 200, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0049] In some embodiments of this application, the secondary battery 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0050] In this application, the secondary battery 100 can refer to a single battery cell 20, or it can refer to a single physical module comprising multiple battery cells 20 to provide higher voltage and capacity, which can be in the form of a battery pack, battery module, etc. The secondary battery 100 may include a housing 10 for encapsulating multiple battery cells 20, and the housing 10 can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cells 20.

[0051] Figure 2 is an exploded structural diagram of a secondary battery 100 provided in some embodiments of this application. Referring to Figure 2, the secondary battery 100 includes a housing 10 and battery cells 20, with the battery cells 20 housed within the housing 10.

[0052] The housing 10 provides a receiving space 11 for the battery cell 20. In some embodiments, the housing 10 may include a first portion 12 and a second portion 13, which overlap each other to define the receiving space 11 for accommodating the battery cell 20. Of course, the connection between the first portion 12 and the second portion 13 may be sealed by a sealant (not shown), such as a sealing ring, sealant, etc.

[0053] The first part 12 and the second part 13 can be of various shapes, such as cuboids, cylinders, etc. The first part 12 can be a hollow structure with one side open to form a cavity for accommodating the battery cell 20, and the second part 13 can also be a hollow structure with one side open to form a cavity for accommodating the battery cell 20. The opening side of the second part 13 covers the opening side of the first part 12, thus forming a box 10 with a accommodating space 11. Of course, as shown in Figure 2, the first part 12 can also be a hollow structure with one side open, and the second part 13 can be a plate-like structure. The second part 13 covers the opening side of the first part 12, thus forming a box 10 with a accommodating space 11.

[0054] In the secondary battery 100, there are multiple battery cells 20. These multiple battery cells 20 can be connected in series, parallel, or in a mixed manner. A mixed connection means that multiple battery cells 20 are connected in both series and parallel. Multiple battery cells 20 can be directly connected in series, parallel, or in a mixed manner, and then the entire assembly of the multiple battery cells 20 is housed within the housing 10. Alternatively, multiple battery cells 20 can first be connected in series, parallel, or in a mixed manner to form a battery module, and then multiple battery modules can be connected in series, parallel, or in a mixed manner to form a whole, which is also housed within the housing 10. The battery cell 20 can be cylindrical, flat, cuboid, or other shapes. Figure 2 illustrates an example of a square battery cell 20.

[0055] In some embodiments, the secondary battery 100 may further include a busbar (not shown), through which multiple battery cells 20 can be electrically connected to each other to achieve series, parallel, or mixed connection of multiple battery cells 20.

[0056] Figure 3 is a schematic diagram of the structure of a battery cell 20 provided in some embodiments of this application, and Figure 4 is an exploded view of a battery cell 20 provided in some embodiments of this application. Referring to Figures 3 and 4, the battery cell 20 may include a housing 21, an end cap assembly 22, and an electrode assembly 23. The housing 21 has an opening 211, the electrode assembly 23 is accommodated within the housing 21, and the end cap assembly 22 is used to seal the opening 211.

[0057] The shape of the housing 21 can be determined according to the specific shape of the electrode assembly 23. For example, if the electrode assembly 23 is a cuboid structure, the housing 21 can also be a cuboid structure. Figures 3 and 4 exemplarily show the case where the housing 21 and the electrode assembly 23 are square.

[0058] The outer shell 21 can also be made of various materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, etc. This application embodiment does not impose any special restrictions on this.

[0059] The end cap assembly 22 includes an end cap 221 and electrode terminals 222. The end cap assembly 22 is used to seal the opening 211 of the housing 21 to form a sealed mounting space (not shown) for accommodating the electrode assembly 23. The mounting space also accommodates an electrolyte, such as an electrolyte solution. As a component that outputs electrical energy to the electrode assembly 23, the end cap assembly 22 has electrode terminals 222 for electrical connection to the electrode assembly 23, specifically, the electrode terminals 222 are electrically connected to the tabs of the electrode assembly 23. For example, the electrode terminals 222 and the tabs are connected via a current collector 24 to achieve the electrical connection between the electrode terminals 222 and the tabs.

[0060] It should be noted that the opening 211 of the outer casing 21 can be one or two. If the outer casing 21 has one opening 211, the end cap assembly 22 can also be one, and two electrode terminals 222 can be provided in the end cap assembly 22. The two electrode terminals 222 are used to electrically connect to the positive electrode tab and the negative electrode tab of the electrode assembly 23, respectively. If the outer casing 21 has two openings 211, for example, the two openings 211 are located on opposite sides of the outer casing 21, the end cap assembly 22 can also be two, and the two end cap assemblies 22 respectively cover the two openings 211 of the outer casing 21. In this case, the electrode terminal 222 in one end cap assembly 22 can be a positive electrode terminal, used to electrically connect to the positive electrode tab of the electrode assembly 23; the electrode terminal 222 in the other end cap assembly 22 can be a negative electrode terminal, used to electrically connect to the negative electrode plate of the electrode assembly 23.

[0061] In some embodiments, as shown in FIG4, the battery cell 20 may further include an insulating protective member 25 fixed to the outer periphery of the electrode assembly 23. The insulating protective member 25 is used to insulate and isolate the electrode assembly 23 from the housing 21. Exemplarily, the insulating protective member 25 is an adhesive tape bonded to the outer periphery of the electrode assembly 23. In some embodiments, there are multiple electrode assemblies 23, and the insulating protective member 25 surrounds the outer periphery of multiple electrode assemblies 23, forming multiple electrode assemblies 23 into an integral structure to maintain the structural stability of the electrode assembly 23.

[0062] The electrode assembly 23 includes a positive electrode sheet, a negative electrode sheet 231, and a separator. The positive electrode sheet includes a positive current collector and a positive active material layer. The positive active material layer is coated on the surface of the positive current collector. The positive current collector without the positive active material layer protrudes from the positive current collector with the positive active material layer coated on it. The positive current collector without the positive active material layer serves as the positive electrode tab.

[0063] The negative electrode 231 includes a negative current collector 2311 and a negative active material layer 2312. The negative active material layer 2312 is coated on the surface of the negative current collector 2311. The negative current collector 2311 without the negative active material layer 2312 coating protrudes from the negative current collector 2311 with the negative active material layer 2312 coating, and the negative current collector 2311 without the negative active material layer 2312 coating serves as a negative electrode tab. The material of the negative current collector 2311 can be copper, and the negative active material can be carbon or silicon, etc. To ensure that a large current can pass through without melting, there are multiple positive electrode tabs stacked together, and there are multiple negative electrode tabs stacked together. The material of the separator can be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly 23 can be a stacked electrode assembly or a wound electrode assembly, and the embodiments of this application are not limited to these.

[0064] This application provides a battery cell comprising an electrolyte and a negative electrode. The electrolyte comprises a solvent, an electrolyte, and a film-forming additive. At least a portion of the negative electrode is immersed in the electrolyte. Figures 5 and 6 are schematic diagrams of the structure of the negative electrode provided in some embodiments of this application. As shown in Figures 5 and 6, the negative electrode comprises a negative current collector, a negative active material layer, and an artificial solid electrolyte interface layer 2313. The negative active material layer is attached to at least a portion of the surface of the negative current collector. The negative active material layer comprises a negative active material, which includes graphite. The thermal decomposition temperature of the graphite is above 800°C. The artificial solid electrolyte interface layer 2313 is disposed between the electrolyte and at least a portion of the negative active material.

[0065] The solvent may be selected from at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate, ethyl acetate, acid anhydride, N-methylpyrrolidone, N-methylformamide, N-methylacetamide, acetonitrile, sulfolane, dimethyl sulfoxide, ethylene sulfite, propylene sulfite, dimethyl sulfide, diethyl sulfite, dimethyl sulfite, tetrahydrofuran, fluorinated cyclic organic esters, and sulfur-containing cyclic organic esters.

[0066] The electrolyte can be selected from one or more organic or inorganic electrolytes. The electrolyte may contain one or more of nitrogen, sulfur, fluorine, boron, and phosphorus. The type of electrolyte is related to the type of secondary battery in which the electrolyte of this application is used. For example, when used in a lithium-ion battery, the electrolyte can be a lithium salt, which can be selected from at least one of organic or inorganic lithium salts. Specifically, the lithium salt can be selected from at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiN(CF3SO2)2) (abbreviated as LiTFSI), lithium bis(fluorosulfonyl)imide (Li(N(SO2F)2)) (abbreviated as LiFSI), lithium bis(oxalatoborate) (LiB(C2O4)2) (abbreviated as LiBOB), lithium difluorooxalatoborate (LiBF2(C2O4)) (abbreviated as LiDFOB), LiBF4, LiClO4, and LiAsF6. When used in sodium-ion batteries, the electrolyte can be a sodium salt, which can be selected from at least one of organic or inorganic sodium salts.

[0067] The role of film-forming additives is to form an SEI (Solid Electrolyte Interphase) film on the surface of the negative electrode during battery cycling. The formation of the SEI film can, to some extent, prevent further decomposition and gas production of the electrolyte, thereby improving battery performance. Film-forming additives can be selected from at least one of sulfur-containing additives, fluorine-containing additives, and vitamin C additives.

[0068] The negative electrode current collector 2311 can be made of one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. Referring to Figure 5, in one embodiment, a negative electrode active material layer 2312 is disposed on one surface of the negative electrode current collector 2311; referring to Figure 6, in another embodiment, a negative electrode active material layer 2312 is disposed on both surfaces of the negative electrode current collector 2311.

[0069] The negative electrode active material of the negative electrode active material layer 2312 can be a carbon material (graphite, soft carbon, hard carbon, mesophase carbon microspheres, carbon fiber, carbon nanotubes, graphene, etc.), a titanium oxide-based material (lithium titanate, titanium dioxide, etc.), an alloyed negative electrode material (silicon-based material, tin-based material, germanium-based material, etc.), or a conversion-type negative electrode material (transition metal oxides, phosphides, sulfides, nitrides, etc.). Among these, the graphite can be selected from one or a combination of artificial graphite, natural graphite, and modified graphite. Graphite can be further modified, and there are no specific restrictions on the modification method, such as coating modification on the graphite surface.

[0070] The artificial solid electrolyte interfacial layer 2313, also known as A-SEI or artificial SEI film, is a thin film formed on the negative electrode active material layer that isolates electrons but has ion-conducting capabilities. It can prevent surface defects of the negative electrode active material and side reactions in the electrolyte, and provides a certain degree of elasticity, reducing interface damage caused by lithium intercalation expansion of the negative electrode active material to some extent. This film contains at least two groups, including carbonyl groups (including but not limited to aldehydes, ketones, carboxylic acids and their salts, carboxylic esters, and acid anhydrides), hydroxyl groups or hydroxyl metals, ether groups, epoxy groups, -C=C-, -C≡C-, -C≡N-, -NH2, and benzene rings, with a molecular weight ≤175. Carboxylate salts and any combination of -C=C- are preferred. It may contain one or more metal elements selected from Li, Na, K, Mg, and Al, preferably Li and Na. The mass percentage of the metal element in the artificial SEI is 4%–60%, preferably 4%–45%. The preparation method can be as follows: a) react organic acid with inorganic salts or bases of Li, Na, K, Mg or Al to generate organic salts or solutions; b1) dry mix active materials, binders, conductive agents, and inorganic salts of Li, Na, K, Mg or Al until uniform; b2) add inorganic salts or solutions and knead, then add DI water, flexible agent and binder in sequence and stir until finished; c) uniformly coat the slurry from step b1 or b2 above onto the surface of the negative electrode current collector or other active layers of the negative electrode current collector, and dry it in an oven at 100-110℃ to prepare a negative electrode sheet containing an artificial solid electrolyte interface phase layer 2313.

[0071] The thermal decomposition temperature refers to the critical temperature at which a material undergoes thermal decomposition. It reflects the material's thermal stability; the higher the thermal decomposition temperature, the higher the material's thermal stability. For example, the thermal decomposition temperature of graphite can be 800℃, 805℃, 810℃, 815℃, 820℃, 825℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, or 900℃, or any value within the range above 800℃.

[0072] This battery cell incorporates a film-forming additive in the electrolyte that can form an SEI film on the surface of the negative electrode during battery cycling. Simultaneously, an artificial solid electrolyte interphase layer 2313 is set on the negative electrode. This allows the artificial solid electrolyte interphase layer 2313 and the SEI film formed by the film-forming additive to work together to reduce the reduction of the electrode liquid on the surface of the negative electrode, thereby slowing down the degradation of the calendar life of the long-cycle secondary battery.

[0073] In some embodiments of this application, the film-forming additives include sulfur-containing additives. Using sulfur-containing additives as film-forming additives not only enables the formation of an SEI film and an artificial solid electrolyte interface layer 2313, thus mitigating the degradation of the calendar life of long-cycle secondary batteries, but also helps to reduce the DC internal resistance (DCR) of the entire battery cell.

[0074] Furthermore, the sulfur-containing additive includes at least one of sulfate ester compounds, sulfite ester compounds, and sulfonyl lactone compounds.

[0075] In some embodiments of this application, the artificial solid electrolyte interface layer 2313 comprises at least one of a lithium carboxyl-containing compound and a sodium carboxyl-containing compound. For example, the lithium carboxyl-containing compound may be lithium maleate, lithium fumarate, lithium acrylate, lithium formate, lithium acetate, lithium propionate, lithium benzoate, lithium phenylacetate, lithium phenylpropionate, lithium itaconic acid, etc., and the sodium carboxyl-containing compound may be sodium maleate, sodium fumarate, sodium acrylate, sodium formate, sodium acetate, sodium propionate, sodium benzoate, sodium phenylacetate, sodium phenylpropionate, sodium itaconic acid, etc.

[0076] In some embodiments of this application, the film-forming additive accounts for 0.01% to 10% of the mass of the electrolyte; and in the negative electrode sheet, the mass ratio of Li and / or Na elements to the negative electrode active material is ≤0.8%.

[0077] The types and contents of additives in the electrolyte can be determined by gas chromatography, gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), liquid chromatography (LC), nuclear magnetic resonance spectroscopy (NMR), and inductively coupled plasma optical emission spectrometry (ICP-OES). For example, the following method can be used: 500 μl of deuterated reagent is added to an NMR tube in a nitrogen-filled glove box, and 100 μl of non-aqueous electrolyte sample is added to the NMR tube. The NMR tube is shaken to dissolve the non-aqueous electrolyte in the deuterated reagent, and the test is performed using an Oxford Instruments X-Pulse benchtop NMR spectrometer. Because the non-aqueous electrolyte is very sensitive to moisture, both the NMR test and sample preparation are conducted in a nitrogen atmosphere (H2O content less than 0.1 ppm, O2 content less than 0.1 ppm). Simultaneously, the instruments used in the test need to be pre-washed with pure water and dried in a vacuum environment at 60°C for at least 48 hours. The deuterated reagent was prepared as follows: Deuterated dimethyl sulfoxide (DMSO-d6), deuterated acetonitrile, and trifluoromethylbenzene were dried using a 4A molecular sieve at a temperature above 25°C for at least 3 days, ensuring that the water content of all reagents was less than 3 ppm. A Metrohm 831KF coulometric moisture analyzer was used for moisture testing. Then, in a nitrogen-filled glove box, 10 ml of dried DMSO-d6 and 300 μl of dried internal standard trifluoromethylbenzene were mixed thoroughly to obtain the first solution. 10 ml of dried deuterated acetonitrile and 300 μl of dried internal standard trifluoromethylbenzene were then mixed thoroughly to obtain the second solution. The first and second solutions were then mixed thoroughly to obtain the deuterated reagent.

[0078] The content of Li and / or Na elements can be obtained by ICP elemental analysis. The specific process is as follows: Take 0.4g of the powder to be tested into a 25ml beaker, add 2ml to 5ml of nitric acid, let it stand overnight, and then place it on a hot plate and heat it at about 100℃ (using a voltage regulator to adjust the input voltage and control the temperature) until the powder is digested. Then add 0.5ml of perchloric acid and heat it at about 140℃ to digest until the white fumes are exhausted. The residue should be white. Otherwise, nitric acid and perchloric acid should be added again for repeated digestion. Finally, dissolve and extract with 7% (volume percentage of acid, the same below) hydrochloric acid. Adjust the volume to an appropriate level according to the content of the element to be tested, and then start testing the content of Li or Na elements on the ICP-OES instrument.

[0079] The amount of film-forming additives can be considered, to some extent, as the thickness of the SEI film. The mass ratio of Li and / or Na elements to the negative electrode active material can be considered, to some extent, as the thickness of the artificial solid electrolyte interfacial layer 2313. A thicker SEI film or artificial solid electrolyte interfacial layer 2313 is more effective in preventing contact between the negative electrode and the electrolyte, thus improving the calendar life of the battery cell. Conversely, a thinner SEI film or artificial solid electrolyte interfacial layer 2313 is more effective in controlling the DC internal resistance (DCR) of the battery cell within a smaller range. By combining the SEI film formed by the artificial solid electrolyte interfacial layer 2313 and the film-forming additives, the thickness of both the SEI film and the artificial solid electrolyte interfacial layer 2313 can be reduced. This allows for control of the mass percentage of the film-forming additives in the electrolyte to be 0.01%–10%, and the mass ratio of Li and / or Na elements to the negative electrode active material to be ≤0.8%, resulting in a better calendar life for the battery cell while maintaining a lower DC internal resistance (DCR).

[0080] For example, the mass percentage of the film-forming additive in the electrolyte can be 0.01%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, or 10%, etc., or it can be any value in the range of 0.01% to 10%. The mass ratio of Li and / or Na elements to the negative electrode active material can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, etc. 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, 0.5%, 0.52%, 0.54%, 0.56%, 0.58%, 0.6%, 0.62%, 0.64%, 0.66%, 0.68%, 0.7%, 0.72%, 0.74%, 0.76%, 0.78%, or 0.8%, etc., or any value within the range of ≤0.8%.

[0081] It should be noted that during the manufacturing process of finished batteries, steps such as formation and aging are performed. Simultaneously, during battery cycling, the film-forming additives in the electrolyte decrease. Therefore, the content of film-forming additives in the electrolyte of a finished battery is less than that of fresh electrolyte (i.e., 0.01%–10%). It is understandable that, apart from the electrolyte, other components in a battery typically do not contain sulfur; therefore, the sulfur in the entire battery can be considered to originate entirely from the electrolyte. Consequently, when determining the amount of sulfur-containing additives used to form the finished battery, this can be calculated by measuring the sulfur content of the entire battery.

[0082] In some embodiments of this application, the film-forming additive accounts for 0.1% to 5% of the mass of the electrolyte; in the negative electrode sheet, the mass ratio of Li and / or Na elements to the negative electrode active material is 0.23% to 0.8%. Controlling the mass ratio of the film-forming additive in the electrolyte to 0.1% to 5% and the mass ratio of Li and / or Na elements to the negative electrode active material to 0.23% to 0.8% results in a better calendar life for the battery cell, while also ensuring a lower DC internal resistance (DCR) for the battery cell.

[0083] In some embodiments of this application, the artificial solid electrolyte interface layer 2313 comprises at least one of compounds containing double bonds, compounds containing epoxy groups, compounds containing carbonyl groups, and compounds containing amine groups. For example, compounds containing double bonds may be selected from acrylonitrile, dibutadiene nitrile, etc.; compounds containing epoxy groups may be selected from 1,3-dioxopentane, cyclohexane oxide, propylene oxide, hexane oxide, etc.; compounds containing carbonyl groups may be selected from benzaldehyde, phenylacetaldehyde, acetophenone, etc.; and compounds containing amine groups may be selected from acrylamide, triallylamine, etc.

[0084] Compounds containing double bonds, epoxy groups, carbonyl groups, and amine groups can be detected using the FTIR (Fourier Transform Infrared Spectroscopy) method. For details, please refer to GB / T6040-2002.

[0085] In some embodiments of this application, the thermal decomposition temperature of graphite is 800℃~830℃. A higher thermal decomposition temperature of graphite is more beneficial to the calendar life of long-cycle batteries, while a lower thermal decomposition temperature is more conducive to obtaining graphite materials, thereby helping to control battery costs. Through the interaction of the artificial solid electrolyte interphase layer 2313 and the SEI film formed by film-forming additives, the stability requirements of long-cycle batteries on graphite can be reduced. By controlling the thermal decomposition temperature of graphite to 800℃~830℃, a good calendar life of long-cycle batteries can be achieved at a lower cost. In other embodiments of this application, the thermal decomposition temperature of graphite is ≥830℃. A higher thermal decomposition temperature of graphite is more beneficial to the calendar life of long-cycle batteries. By controlling the thermal decomposition temperature of graphite to ≥830℃, it is beneficial to improve the calendar life of long-cycle batteries.

[0086] The thermal decomposition temperature of graphite can be determined using thermogravimetric analysis (TG-T). The specific procedure is as follows: 10 mg of the graphite sample is taken for TG-T analysis. The gas flow rate is 60 mL / min, the heating rate is 5 °C / min, and the test temperature range is 40 °C to 950 °C. The test data are plotted as a DTG-T curve, and the peak temperature of the largest peak in the DTG-T curve is recorded as the thermal decomposition temperature.

[0087] Having introduced the materials and structure of the battery cell 20, the preparation method of the battery cell 20 will be described in detail below.

[0088] The preparation method of the battery cell 20 includes the following steps: mixing the negative electrode active material, A-SEI raw material, conductive agent, thickener and binder, and then mixing with solvent to prepare a negative electrode active slurry. The negative electrode active slurry is coated on the negative electrode current collector 2311 to obtain the negative electrode sheet 231. After preparing the negative electrode sheet 231, the positive electrode sheet, separator, negative electrode sheet 231 and separator are stacked in sequence to form a stacked electrode assembly 23. Then the electrode assembly 23 is placed in the housing and electrolyte is injected to form the battery cell 20.

[0089] It should be noted that when the A-SEI raw material is alkaline, such as compounds containing sodium carboxyl, gelation is easily generated during the preparation of the negative electrode active slurry, which leads to poor dispersion. Therefore, the pH value of the A-SEI raw material can be adjusted to close to 7. For example, for compounds containing sodium carboxyl, the degree of Na substitution (i.e., the ratio of Na to H) can be adjusted.

[0090] Figure 7 is a flowchart of the preparation process of the battery cell 20 provided in some embodiments of this application. As shown in Figure 7, the specific process of preparing the battery cell 20 is as follows:

[0091] S210, Preparation of negative electrode active slurry: The negative electrode active material, A-SEI raw material, binder, thickener, and conductive agent are dispersed in a solvent to form a negative electrode active slurry. The negative electrode active material used is the one provided above. Optionally, a small amount of other negative electrode active materials may be added.

[0092] The binder can be one or more of styrene-butadiene rubber, waterborne acrylic resin, carboxymethyl cellulose, polyvinylidene fluoride, polytetrafluoroethylene, ethylene-vinyl acetate copolymer, polyvinyl alcohol, and polyvinyl butyral. The conductive agent can be at least one of conductive carbon black, carbon fiber, carbon nanotubes, Ketjen black, graphene, or acetylene black. The solvent can be one or more of dimethyl glutarate and N-methylpyrrolidone. Leveling agents, dispersants, etc., can also be added to the positive electrode active slurry.

[0093] S220, Preparation of negative electrode active material layer 2312: The negative electrode active slurry is coated on the surface of the negative electrode current collector 2311 and then dried to form the negative electrode active material layer 2312. During coating, it can be applied to one or both surfaces of the negative electrode current collector 2311 as needed.

[0094] The coating method can be: scraping, roller coating, slot coating, etc., and this application does not limit it.

[0095] The negative electrode current collector 2311 can be a metal foil or a composite current collector. For example, copper foil can be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0096] S230, roll-press the negative electrode active material layer 2312 to obtain the negative electrode sheet 231.

[0097] S240, the positive electrode plate, the separator, the negative electrode plate 231, the separator, and so on are stacked in sequence to form a stacked electrode assembly 23.

[0098] S250, the stacked electrode assembly 23 is assembled into a battery cell 20. This battery cell 20 can be used to prepare a secondary battery 100 and provide electrical energy to an electrical device.

[0099] The following examples will describe one or more embodiments in more detail. Of course, these examples do not limit the scope of the one or more embodiments.

[0100] Examples and Comparative Examples

[0101] Preparation of the positive electrode sheet

[0102] 2.5 wt% of the binder polyvinylidene fluoride was fully dissolved in the solvent N-methylpyrrolidone. 2.0 wt% of super P and 1.0 wt% of CNT were added as conductive agents, and 94.5 wt% of the positive electrode active material LFP were used to prepare a uniformly dispersed slurry. The slurry was uniformly coated onto the surface of the positive electrode current collector aluminum foil, and after drying, cold pressing, and slitting, the positive electrode sheet was obtained.

[0103] Preparation of the negative electrode sheet

[0104] ① Preparation of the artificial solid electrolyte interfacial phase layer 2313 using a slurry method: Artificial graphite (active material), carbon nanotubes (conductive agent), styrene-butadiene rubber (SBR) (binder), and sodium carboxymethyl cellulose (CMC) (thickener) are prepared in a mass ratio of 90:5:3:2. A-SEI raw material is then mixed in and dissolved in deionized water. After thorough mixing, a negative electrode slurry is prepared. This slurry is then uniformly coated onto the negative electrode current collector copper foil one or more times. After drying, cold pressing, and slitting, the negative electrode sheet is obtained. (This method is referred to as the slurry method.)

[0105] ② Preparation of the artificial solid electrolyte interfacial layer 2313 by spraying: Active material artificial graphite, conductive agent carbon nanotubes, binder styrene-butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC) are dissolved in deionized water at a mass ratio of 90:5:3:2 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is uniformly coated onto the negative electrode current collector copper foil once or multiple times. After drying, cold pressing, and slitting, a semi-finished product is obtained. A-SEI raw material is then sprayed onto the negative electrode active layer to complete the preparation of the negative electrode sheet. (This method is referred to as the spraying method.)

[0106] Preparation of Electrolyte

[0107] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), the organic solvents ethylene carbonate (EC) / diethyl carbonate (DEC) / ethyl methyl carbonate (EMC) are mixed evenly in a volume ratio of 1 / 1 / 1. 1 mol / L NaPF6 sodium salt is added and dispersed evenly. The film-forming additive is then dissolved in the above organic solvent and stirred evenly to obtain the electrolyte.

[0108]

Isolation Film

[0109] Polyethylene film is used as the separation membrane.

[0110] [Preparation of battery cells]

[0111] The prepared positive electrode sheet, negative electrode sheet, and separator (polyethylene (PE) porous polymer film) are stacked in a Z-shaped structure to form corresponding electrode assemblies. The electrode assemblies are vacuum dried at 90℃ for 12 hours, followed by ultrasonic welding of the positive and negative electrode tabs. The positive electrode uses aluminum tabs, and the negative electrode uses nickel tabs, with the tabs located on the same side of the electrode assembly. The electrode assembly with welded tabs is then placed into an aluminum-plastic film of appropriate size for top and side sealing at a temperature of 145℃. Electrolyte is then injected and the assembly is sealed to obtain an uncharged battery. The uncharged battery then undergoes a series of processes including settling, hot and cold pressing, formation, shaping, and capacity testing to obtain a single battery cell.

[0112] The main parameter controls for Examples 1 to 24 and Comparative Examples 1 to 3 are shown in the table below:

[0113] The performance of the positive electrode active materials and batteries composed thereof provided in each embodiment and comparative example was tested. The performance testing specifically included:

[0114] DCR Test: At 25℃, charge the battery at a rate of 0.33C to the upper limit voltage of 3.65V (LFP system), then maintain the voltage at a constant current of 0.05C, and let it stand for 10 minutes. At 25℃, discharge the battery at a rate of 0.33C to 50% SOC. Use a rate of 1C to discharge and charge the battery for 20 seconds. Mark the voltage before discharge as U0, the voltage after discharge as U1, and the discharge rate of 1C as I. Then, the DC resistance DCR of the secondary battery at different SOCs is (U0-U1) / I.

[0115] Calendar life test: The secondary battery is charged at a constant current rate of 0.33C to a voltage of 3.65V at 25℃, then charged at a constant voltage of 3.65V until the current is less than or equal to 0.05C. After that, it is left to stand for 10 minutes, and then discharged at a constant current rate of 0.1C to a voltage of 2V (the capacity of this step is marked as C2). The secondary battery was then charged at a constant current rate of 0.33C to a voltage of 3.65V, and then charged at a constant voltage of 3.65V until the current was less than or equal to 0.05C. At this point, the secondary battery was fully charged and stored at 60℃ for 60 days. Then, the secondary battery was transferred to a 25℃ environment and discharged at a constant current rate of 0.33C to a voltage of 2V. Finally, it was charged at a constant current rate of 0.1C to a voltage of 3.65V, and then charged at a constant voltage of 3.65V until the current was less than or equal to 0.05C. After that, it was left to stand for 10 minutes, and then discharged at a constant current rate of 0.1C to a voltage of 2V (the capacity at this step is marked as C90). The reversible capacity retention rate of the secondary battery during storage was calculated as R2 = C90 ÷ C2 × 100%. The larger the value of R2, the better the storage performance.

[0116] Capacity retention test: At room temperature (25℃), the lithium-ion secondary battery was first charged to 3.65V with a constant current of 0.5C, then further charged to 0.05C with a constant voltage of 3.65V, and finally discharged to 2.5V with a constant current of 0.5C. This constitutes one charge-discharge cycle, and the discharge capacity of this cycle is the discharge capacity of the first cycle. The battery was subjected to multiple charge-discharge cycles in the above manner to obtain the number of cycles in which the discharge capacity is 80% of the discharge capacity of the first cycle.

[0117] The test results are shown in the table below:

[0118] It should be noted that the test results of the above embodiments and comparative examples were obtained with the battery capacity measured under a design of 131mAh.

[0119] As can be seen from the table above, the battery provided in the embodiments of this application has good cycle performance and a long calendar life.

[0120] By comparing the data of Comparative Example 1, Example 1 and Example 2, it can be seen that as the thermal decomposition temperature of graphite, the negative electrode active material, increases, the cycle performance and calendar life both show a gradual improvement trend. By controlling the thermal decomposition temperature above 800°C, the battery degradation can be controlled below 3.8% after 60 days of storage at 60°C, and the number of cycles at 25°C to 80% degradation is above 13,500.

[0121] A comparison of the data from Examples 2 to 5 shows that using sulfur-containing compounds as film-forming additives can achieve good cycle performance and a long calendar life while maintaining a low DC impedance (DCR).

[0122] A comparison of the data from Examples 2 and 6 to 9 shows that as the artificial solid electrolyte interfacial phase layer gradually thickens, the battery's calendar life gradually improves, but the battery's DC resistance gradually increases. By controlling the mass ratio of Li and / or Na elements to the negative electrode active material to not exceed 0.5%, a good calendar life and low DC resistance can be achieved.

[0123] A comparison of the data from Examples 10 to 13 shows that as the content of film-forming additives gradually increases, the DC resistance and calendar life of the battery both show a trend of first improving and then deteriorating. By controlling the mass ratio of film-forming additives in the electrolyte to 0.01% to 10%, the battery degradation can be controlled to below 4.2% after 60 days of storage at 60°C, while the battery also has a low DC resistance.

[0124] A comparison of the data from Examples 2 and 11 shows that the battery with the artificial solid electrolyte interface layer 2313 prepared by the spraying method has lower DC impedance, better calendar life, and better cycle performance compared to the battery with the artificial solid electrolyte interface layer 2313 prepared by the slurry method.

[0125] The above are merely specific embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A battery cell, characterized by, The battery cell includes an electrolyte and a negative electrode tab, the electrolyte includes a solvent, an electrolyte, and a film-forming additive; the negative electrode tab includes a negative electrode current collector, a negative electrode active material layer, and an artificial solid electrolyte interface phase layer, the negative electrode active material layer is attached to at least part of the surface of the negative electrode current collector; the negative electrode active material layer includes a negative electrode active material, the negative electrode active material includes graphite, the thermal decomposition temperature of the graphite is 800 DEG C or higher, and the artificial solid electrolyte interface phase layer is provided between the electrolyte and at least part of the negative electrode active material.

2. The battery cell of claim 1, wherein, The film-forming additive includes a sulfur-containing additive.

3. The battery cell of claim 2, wherein, The sulfur-containing additive includes at least one of a sulfate compound, a sulfite compound, and a sulfonic acid lactone compound.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The component of the artificial solid electrolyte interface phase layer includes a carboxylate.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The component of the artificial solid electrolyte interface phase layer includes at least one of a carboxyl lithium-containing compound and a carboxyl sodium-containing compound.

6. The battery cell of claim 5, wherein, The mass ratio of the film-forming additive in the electrolyte is 0.01% to 10%; in the negative electrode tab, the mass ratio of Li and / or Na element to negative electrode active material is ≤0.8%.

7. The battery cell of claim 6, wherein, The mass ratio of the film-forming additive in the electrolyte is 0.1% to 5%; in the negative electrode tab, the mass ratio of Li and / or Na element to negative electrode active material is 0.23% to 0.8%.

8. The battery cell of any one of claims 1 to 3, wherein, The component of the artificial solid electrolyte interface phase layer includes at least one of a double bond-containing compound, an epoxy group-containing compound, a carbonyl group-containing compound, and an amine group-containing compound.

9. The battery cell of any one of claims 1 to 8, wherein, The thermal decomposition temperature of the graphite is 800 DEG C to 830 DEG C.

10. A battery, characterized by The battery includes the battery cell of any one of claims 1 to 9.

11. An electrical device, characterized by The electric device includes the battery cell of any one of claims 1 to 9 or the battery of claim 10.

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