Battery cell, battery device, and electric device

Abstract

The application provides a battery monomer and a power device, the battery monomer comprising a positive pole sheet, a negative pole sheet and an electrolyte, the electrolyte comprising a first additive and a second additive, the first additive comprising a sulfonic anhydride compound, and the second additive comprising one or more of a sulfuric ester compound, a sulfurous acid ester compound and a sulfonic acid ester compound, wherein the difference between the reduction potential of the first additive relative to Li + and the reduction potential of the second additive relative to Li + is 0.2V-1.5V.

Description

Technical Field

[0001] This application relates to the field of battery cell technology, and more particularly to a battery cell, a battery device, and an electrical device. Background Technology

[0002] In recent years, battery cells have been widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric cars, military equipment, and aerospace.

[0003] With the development of battery cell applications, higher requirements are being placed on the performance of battery cells, such as kinetic performance. Summary of the Invention

[0004] This application provides a battery cell, a battery device, and an electrical device that can reduce the initial DC impedance of the battery cell and the DC impedance growth rate during cycling, thereby improving the dynamic performance of the battery cell.

[0005] A first aspect of this application provides a battery cell comprising a positive electrode, a negative electrode, and an electrolyte. The electrolyte includes a first additive and a second additive. The first additive includes a sulfonic anhydride compound, and the second additive includes one or more of a sulfate ester compound, a sulfite ester compound, and a sulfonate ester compound.

[0006] Wherein the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.2V-1.5V.

[0007] Sulfonic anhydride compounds contain a relatively high amount of sulfur, which helps to increase the mass ratio of sulfur-containing compounds in the SEI film, thereby improving the SEI film's corrosion resistance and thermal stability. Additionally, the electrolyte contains sulfate, sulfite, or sulfonate compounds with a reduction potential difference of 0.2V-1.5V from the sulfonic anhydride compounds. These two additives have different reduction potentials. As the voltage increases, the two additives can undergo two types of redox reactions at the negative electrode interface, resulting in two depositions. The SEI film generated by the additive with the relatively lower reduction potential can repair the SEI film generated by the additive with the relatively higher reduction potential, promoting the formation of a high-smoothness SEI film. This further improves the cycle stability of the SEI film, reduces the possibility of continuous SEI film loss and regeneration and continuous increase in DC internal resistance during battery cell cycling, and lowers the initial DC impedance and the rate of increase in DC impedance during cycling, thus improving the kinetic performance of the battery cell.

[0008] In any embodiment, the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.3V-0.5V.

[0009] The difference in reduction potential between the first additive and the second additive is within a suitable range, which allows the compound generated by the subsequent reduction to better repair the SEI film generated earlier. This is beneficial for generating a dense and smooth SEI film, reducing the initial DC impedance of the battery cell and the rate of increase of DC impedance during cycling, and thus improving the dynamic performance of the battery cell.

[0010] In any embodiment, the sulfonic anhydride compound relative to Li + The reduction potential of Li is 1.2V-1.6V, and / or,

[0011] The sulfate ester compounds relative to Li + The reduction potential of Li is 1.1V-1.9V, and / or,

[0012] The sulfite compounds relative to Li + The reduction potential of Li is 1.7V-2.1V, and / or,

[0013] The sulfonate compounds relative to Li + The reduction potential of / Li is 0.8V-1.8V.

[0014] The first and second additives have suitable reduction potentials, achieving the desired reduction potential of the first additive relative to Li. + / Li reduction potential and the second additive relative to Li + The goal is to achieve a reduction potential difference of 0.2V-0.5V between Li and the target material, thereby forming a highly smooth SEI film through two depositions. This reduces the initial DC impedance of the battery cell and the rate of increase in DC impedance during cycling, which is beneficial for improving the dynamic performance of the battery cell.

[0015] In any embodiment, the first additive is relative to Li + The reduction potential of / Li is greater than that of the second additive relative to Li. + The reduction potential of / Li, wherein the mass ratio of the first additive to the second additive is 10:1-1:1, and can be selected as 5:1-1:1;

[0016] Or the first additive relative to Li + The reduction potential of / Li is lower than that of the second additive relative to Li. +The reduction potential of / Li, the mass ratio of the second additive to the first additive is 10:1-1:1, and can be selected as 5:1-1:1.

[0017] When the mass ratio of the first additive to the second additive is within a suitable range, the first SEI film formed is relatively thick and complete, reducing the possibility of side reactions between the electrolyte and the negative electrode active material, reducing the possibility of rapid SEI film thickening, and reducing the initial DC resistance and DC resistance growth rate of the battery cell during cycling. At the same time, the second SEI film formed is relatively thin, which is beneficial for repairing the first SEI film, improving the overall smoothness and stability of the SEI film, reducing the possibility of continuous SEI film loss and regeneration and continuous DC internal resistance growth in the battery cell during cycling, and reducing the initial DC resistance and DC resistance growth rate of the battery cell during cycling, which is beneficial for improving the dynamic performance of the battery cell.

[0018] In any embodiment, based on the mass of the electrolyte, the mass content of the first additive is 0.01%-10%, optionally 0.01%-5%; and / or,

[0019] The second additive has a mass content of 0.01%-10%, optionally 0.01%-5%.

[0020] Controlling the mass content of the first and second additives within a suitable range allows for the formation of a relatively thick and complete SEI film in the first stage and a relatively thin SEI film in the second stage. This facilitates the formation of a suitable and flat SEI film, improves the overall stability of the SEI film, and reduces the initial DC resistance of the battery cell and the rate of increase of DC resistance during cycling.

[0021] In any embodiment, the sulfonic anhydride compound includes one or more of the following compounds:

[0022]

[0023] And / or, the sulfate ester compounds include one or more of vinyl sulfate (DTD), ethylene disulfate (2-DTD), ethylene trisulfate (3-DTD), 4-methyl vinyl sulfate, 4-ethyl vinyl sulfate, 4-propyl vinyl sulfate, 4-butyl vinyl sulfate, and their derivatives.

[0024] And / or, the sulfite compounds include one or more of vinyl sulfite (ES), vinyl vinyl sulfite (VES), butylene sulfite (BS), propylene sulfite (TMS), and their derivatives.

[0025] And / or, the sulfonate compounds include one or more of 1,3-propanesulfonate lactone (PS), 1,3-propenesulfonate lactone (PES), 1,4-butanesulfonate lactone (1,4-BS), methylene disulfonate (MMDS), and their derivatives.

[0026] In any embodiment, the electrolyte further includes a third additive, which comprises a carbonate compound, including one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and vinyl ethylene carbonate (VEC).

[0027] The SEI film generated by the first and second additives is mainly composed of sulfur-containing organic compounds, while the SEI film generated by the third additive is mainly composed of inorganic compounds. When used together, these three additives can form an SEI film containing both inorganic and sulfur-containing organic compounds during the battery's charge and discharge process. This further improves the overall density, mechanical strength, flexibility, and stability of the SEI film, reducing the likelihood of it breaking during cycling. This combination allows for a balance between the battery's kinetic performance, storage stability, and cycle life.

[0028] In any embodiment, the mass ratio of the third additive to the sum of the masses of the first additive and the second additive is 0.5:1-5:1, and can be selected as 1.1:1-2:1.

[0029] The ratio of the mass of the third additive to that of the first and second additives is within a suitable range, so that the proportion of sulfur-containing organic compounds and inorganic compounds in the SEI film is within a suitable range, so that the SEI film can balance strength and flexibility, obtain an SEI film with good rigidity and elasticity, reduce the possibility of SEI film rupture during cycling, and reduce the initial DC impedance of the battery cell and the DC impedance growth rate during cycling.

[0030] In any embodiment, based on the mass of the electrolyte, the mass content of the third additive is 0.01%-10%, optionally 3%-6%.

[0031] By controlling the mass content of the third additive within a suitable range, the mass content of inorganic compounds in the SEI film is also within a suitable range. This not only improves the strength of the SEI film but also keeps the thickness of the SEI film layer within a suitable range, thereby reducing the initial DC resistance of the battery cell and the rate of increase of DC resistance during cycling.

[0032] The second aspect of this application provides a battery device comprising the battery cell described in the first aspect, wherein the battery device includes at least one of a battery module, a battery pack, and an energy storage battery.

[0033] A third aspect of this application is an electrical device, characterized in that it includes the battery cell described in the first aspect. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application.

[0035] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0036] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application.

[0037] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application.

[0038] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown.

[0039] Figure 6 This is a schematic diagram of an electrical device using a battery device as a power source according to an embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1 Battery pack; 2 Upper casing; 3 Lower casing; 4 Battery module; 5 Battery cell; 51 Housing; 52 Electrode assembly; 53 Cover plate Detailed Implementation

[0042] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the battery cell, battery device, and power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0043] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, 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 specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, 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 expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0044] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0045] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0046] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0047] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0048] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0049] Electrolyte is a crucial component of a battery cell. Its key function involves the decomposition reaction of solvents and additives at the positive and negative electrode surfaces, forming a solid electrolyte interphase (SEI) film with a certain mechanical strength and thickness. This SEI film is non-conductive but can conduct active ions. The stability, thickness, and selective permeability of the SEI film affect the kinetic performance of the battery cell. To improve SEI film stability, film-forming additives are typically added to the electrolyte. Commonly used additives include sulfur-containing additives such as vinyl sulfate, vinyl disulfate, vinyl sulfite, propylene sulfite, 1,3-propanesulfonate lactone, and methylene disulfonate, as well as carbonate compounds such as vinylene carbonate. However, the SEI film formed using these commonly used additives still falls short of practical requirements.

[0050] electrolyte

[0051] The electrolyte includes a first additive and a second additive. The first additive includes sulfonic anhydride compounds, and the second additive includes one or more of sulfate compounds, sulfite compounds, and sulfonate compounds.

[0052] Wherein the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.2V-1.5V.

[0053] In this document, the term "sulfonic anhydride compounds" refers to compounds including sulfonic anhydride groups (-SO2-O-SO2-) and their derivatives, as well as mixtures containing such compounds and their derivatives. Compounds including sulfonic anhydride groups (-SO2-O-SO2-) can be chain compounds or cyclic compounds.

[0054] In this document, the term "sulfate ester compound" refers to compounds comprising a sulfate ester group (-O-SO2-O-) and their derivatives, as well as mixtures containing such compounds and their derivatives. Compounds comprising a sulfate ester group (-O-SO2-O-) can be chain compounds or cyclic compounds.

[0055] In this document, the term "sulfite compounds" refers to compounds comprising sulfite groups (-O-SO-O-) and their derivatives, as well as mixtures containing such compounds and their derivatives. Compounds comprising sulfite groups (-O-SO-O-) can be chain compounds or cyclic compounds.

[0056] In this document, the term "sulfonate esters" refers to compounds comprising sulfonate ester groups (-SO2-O-) and their derivatives, as well as mixtures containing such compounds and their derivatives. Compounds comprising sulfonate ester groups (-SO2-O-) can be chain compounds or cyclic compounds.

[0057] The components of the additives can be tested using any method known in the art, such as liquid chromatography, ultraviolet spectrophotometry, or ultraviolet-visible spectrophotometry. For example, an ion chromatograph (IC) can be used to test the inorganic content in the electrolyte. A quantitative amount of electrolyte (the concentration of the diluent is in the middle of the standard curve) is weighed and diluted to 100 mL with ultrapure water. The ion chromatogram is automatically injected and detected, and the inorganic ion chromatogram is obtained. The peak positions are compared to identify the corresponding inorganic compounds. The above free electrolyte is diluted 3–10 times with acetonitrile to obtain the electrolyte dilution to be tested. Using a GC-MS3100 organic component gas chromatograph, the above electrolyte dilution is placed in the instrument for full-scan qualitative analysis. The injection port temperature is 250°C, and the scan range is 35 μm–270 μm. After the test, a total ion chromatogram of each organic compound is obtained, and the peak positions are compared to identify the corresponding organic compounds.

[0058] In some embodiments, the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.2V-1.5V, and can be selected from 0.2V, 0.3V, 0.4V, 0.5V, 0.7V, 1.0V, 1.2V, 1.5V or any value between the two.

[0059] In this paper, the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between Li and Li includes the first additive relative to Li. + / Li reduction potential minus the second additive relative to Li + The reduction potential of Li also includes the second additive relative to Li. + / Li reduction potential minus the first additive relative to Li + / Li reduction potential.

[0060] In some embodiments, sulfonic anhydride compounds relative to Li + The reduction potential of / Li is 1.2V-1.6V.

[0061] In some embodiments, sulfate compounds relative to Li + The reduction potential of / Li is 1.1V-1.9V.

[0062] In some embodiments, the sulfite compounds have a reduction potential of 1.7V-2.1V relative to Li+ / Li.

[0063] In some embodiments, the sulfonate compound has a reduction potential of 0.8V-1.8V relative to Li+ / Li.

[0064] In this paper, "reduction potential" and "reduction potential relative to Li+ / Li" refer to the redox potential of the additive itself relative to Li ions, while "reaction potential" and "film formation reaction potential in the full cell" refer to the potential at which film formation begins during the formation stage in a full cell with graphite as the anode. Reaction potential = 3.4V - relative to Li + The higher the reduction potential of the additive, the lower its reaction potential. During the charging process of a single battery cell, the additive is preferentially reduced.

[0065] In the embodiments of this application, the reduction potentials of the first additive and the second additive have meanings known in the art and can be detected using equipment and methods known in the art. Taking 1,3-propanedisulfonic anhydride as an example, its reduction potential relative to Li / Li is detected. + The reduction potential; specifically,

[0066] Step (1) Electrolyte preparation: Prepare the electrolyte in a glove box filled with nitrogen atmosphere, controlling the moisture and oxygen levels below 5 ppm. Mix ethylene carbonate (EC) and ethyl methyl carbonate (EMC) at a mass ratio of 3:7, and then add LiPF6 to prepare the Base electrolyte. Add 1,3-propanedisulfonic anhydride to the Base electrolyte to obtain the experimental electrolyte, wherein the mass content of LiPF6 is 12.5% ​​and the mass content of 1,3-propanedisulfonic anhydride is 2%. If other additives are to be tested, 1,3-propanedisulfonic anhydride can be replaced with other additives.

[0067] Step (2) Preparation of button cell: In a glove box filled with nitrogen atmosphere, place the positive electrode sheet in the center of the positive electrode shell, add the electrolyte prepared in step (1) (Base electrolyte or experimental electrolyte), the positive electrode sheet can be prepared in the same way as in Example 1; attach the separator PP from one side of the positive electrode sheet to the other side, and make the separator completely wetted by the electrolyte with basically no bubbles; invert the lithium sheet and the negative electrode shell together on the positive electrode shell, press them tightly, and then seal the battery with a sealing film to prepare the CR2025 button cell.

[0068] Step (3) Test of restoration potential: The test was conducted using a charge-discharge apparatus in a constant temperature room at 25℃. The discharge was performed from 3.0V to 0V at a scan rate of 0.05C / s. The data were plotted as Dq / Dv curves, and the Base group was compared to observe whether there were any new peaks and their positions. The voltage value corresponding to the highest peak value among the new peaks was the restoration potential.

[0069] Sulfonic anhydride compounds contain a relatively high amount of sulfur, which helps to increase the mass ratio of sulfur-containing compounds in the SEI film, thereby improving the SEI film's corrosion resistance and thermal stability. At the same time, sulfonic anhydride compounds are easily hydrolyzed and are more sensitive to the water content in the electrolyte. Sulfonic anhydride compounds can react with water in the electrolyte to generate sulfonic acid compounds, reducing the impact of water in the electrolyte on the safety and cycle performance of the battery system. Therefore, sulfonic anhydride compounds can not only be used as film-forming additives to form SEI films with good stability, but also as dehydrating agents to reduce the water content in the electrolyte. In addition, the electrolyte contains sulfate esters, sulfites, or sulfonates with a reduction potential difference of 0.2V-1.5V from sulfonic anhydride compounds. The two additives have different reduction potentials. As the voltage increases, the two additives can undergo two types of redox reactions at the negative electrode interface, resulting in two depositions. The SEI film generated by the additive with the relatively lower reduction potential can repair the SEI film generated by the additive with the relatively higher reduction potential, which is conducive to the formation of a smooth and dense SEI film. This further improves the cycle stability of the SEI film, reduces the possibility of continuous SEI film loss and regeneration and continuous increase in DC internal resistance during the cycle of the battery cell, and reduces the initial DC impedance and the rate of increase of DC impedance during the cycle of the battery cell, which is beneficial to improving the dynamic performance of the battery cell.

[0070] In some embodiments, the reduction potential of the first additive relative to Li+ / Li is different from that of the second additive relative to Li+ / Li. + The difference in reduction potential between / Li is 0.3V-0.5V.

[0071] In some embodiments, the reduction potential of the first additive relative to Li+ / Li is different from that of the second additive relative to Li+ / Li. +The difference in reduction potential between / Li can be selected as 0.3V, 0.4V, 0.5V or any value between the two.

[0072] The difference in reduction potential between the first additive and the second additive is within a suitable range, which allows the compound generated by the subsequent reduction to better repair the SEI film generated earlier. This is beneficial for generating a dense and smooth SEI film, reducing the initial DC impedance of the battery cell and the rate of increase of DC impedance during cycling, and thus improving the dynamic performance of the battery cell.

[0073] In some embodiments, the first additive is relative to Li + The reduction potential of / Li is greater than that of the second additive relative to Li. + The reduction potential of / Li, the mass ratio of the first additive to the second additive is 10:1-1:1, and can be selected as 5:1-1:1.

[0074] In some embodiments, the first additive is relative to Li + The reduction potential of / Li is lower than that of the second additive relative to Li. + The reduction potential of / Li, the mass ratio of the second additive to the first additive is 10:1-1:1, and can be selected as 5:1-1:1.

[0075] In some embodiments, the mass ratio of the first additive to the second additive is 10:1 to 1:1, and can be selected as 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1 or any range between the two.

[0076] In some embodiments, the mass ratio of the second additive to the first additive is 10:1 to 1:1, and can be selected as 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1 or any range between the two.

[0077] The mass or mass ratio of additives in the electrolyte can be obtained by detecting the electrolyte using methods known to those skilled in the art. For example, the composition of the electrolyte can be determined by liquid chromatography, ultraviolet spectrophotometry, or ultraviolet-visible spectrophotometry. For instance, using an ion chromatograph (IC) to test the inorganic content in the electrolyte, a quantitative amount of electrolyte (with a dilution concentration at the midpoint of the standard curve) is weighed and diluted to 100 mL with ultrapure water. The ion chromatogram is automatically injected to detect the inorganic ions. The chromatogram peak positions are compared to identify the corresponding inorganic ions, and the percentage of the corresponding inorganic ion content is calculated based on the peak area. The above-mentioned free electrolyte was diluted 3 to 10 times with acetonitrile to obtain the diluted electrolyte solution to be tested. Using a GC-MS 3100 organic component gas chromatograph, the diluted electrolyte solution was subjected to full-scan qualitative analysis. The injection port temperature was 250℃, and the scan range was 35μm to 270μm. After the test, total ion chromatograms of each organic compound were obtained. The peak positions were compared to identify the corresponding organic compounds, and the percentage content of each organic compound was calculated based on the peak area. The calculated mass of each additive was divided by the mass of the electrolyte sample to obtain the mass content of each additive in the electrolyte of the battery cell. It can be understood that the mass content of each additive in the electrolyte of the battery cell is slightly lower than the added mass content of each additive in the electrolyte of the battery cell.

[0078] When the mass ratio of the first additive to the second additive is within a suitable range, the first SEI film formed is relatively thick and complete, reducing the possibility of side reactions between the electrolyte and the negative electrode active material, reducing the possibility of rapid SEI film thickening, and reducing the initial DC resistance and DC resistance growth rate of the battery cell during cycling. At the same time, the second SEI film formed is relatively thin, which is beneficial for repairing the first SEI film, improving the overall smoothness and stability of the SEI film, reducing the possibility of continuous SEI film loss and regeneration and continuous DC internal resistance growth in the battery cell during cycling, and reducing the initial DC resistance and DC resistance growth rate of the battery cell during cycling, which is beneficial for improving the dynamic performance of the battery cell.

[0079] In some embodiments, based on the mass of the electrolyte, the mass content of the first additive is 0.01%-10%, selectable as 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10.0%, or any range between the two.

[0080] In some embodiments, based on the mass of the electrolyte, the mass content of the second additive is 0.01%-10%, selectable as 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10.0%, or any range between the two.

[0081] Controlling the mass content of the first and second additives within a suitable range allows for the formation of a relatively thick and complete SEI film in the first stage and a relatively thin SEI film in the second stage. This facilitates the formation of a suitable and flat SEI film, improves the overall stability of the SEI film, and reduces the initial DC resistance of the battery cell and the rate of increase of DC resistance during cycling.

[0082] In some embodiments, the sulfonic anhydride compound includes one or more of the following compounds:

[0083]

[0084] In some embodiments, the sulfate ester compounds include one or more of vinyl sulfate (DTD), ethylene disulfate (2-DTD), ethylene trisulfate (3-DTD), 4-methyl vinyl sulfate, 4-ethyl vinyl sulfate, 4-propyl vinyl sulfate, 4-butyl vinyl sulfate, and their derivatives.

[0085] In some embodiments, the sulfite compounds include one or more of vinyl sulfite (ES), vinyl vinyl sulfite (VES), butylene sulfite (BS), propylene sulfite (TMS), and their derivatives.

[0086] In some embodiments, the sulfonate compounds include one or more of 1,3-propanesulfonate lactone (PS), 1,3-propenesulfonate lactone (PES), 1,4-butanesulfonate lactone (1,4-BS), methylene methane disulfonate (MMDS), and their derivatives.

[0087] In some embodiments, the electrolyte further includes a third additive, which comprises a carbonate compound, including one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and vinyl ethylene carbonate (VEC).

[0088] The identification of the third additive in the electrolyte and the method for testing its mass content shall refer to the identification and mass content testing methods of the first and second additives described above.

[0089] The SEI film generated by the first and second additives is mainly composed of sulfur-containing organic compounds, while the SEI film generated by the third additive is mainly composed of inorganic compounds. When used together, these three additives can form an SEI film containing both inorganic and sulfur-containing organic compounds during the battery's charge and discharge process. This further improves the overall density, mechanical strength, flexibility, and stability of the SEI film, reducing the likelihood of it breaking during cycling. This combination allows for a balance between the battery's kinetic performance, storage stability, and cycle life.

[0090] In some embodiments, the mass ratio of the third additive to the sum of the masses of the first and second additives is 0.5:1 to 5:1, and can be selected as 0.5:1, 1:1, 1.5:1, 2.0:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1 or any range between the two.

[0091] The ratio of the mass of the third additive to that of the first and second additives is within a suitable range, so that the proportion of sulfur-containing organic compounds and inorganic compounds in the SEI film is within a suitable range, so that the SEI film can balance strength and flexibility, obtain an SEI film with good rigidity and elasticity, reduce the possibility of SEI film rupture during cycling, and reduce the initial DC impedance of the battery cell and the DC impedance growth rate during cycling.

[0092] In some embodiments, based on the mass of the electrolyte, the mass content of the third additive is 0.01%-10%, selectable as 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10.0%, or any range between the two.

[0093] By controlling the mass content of the third additive within a suitable range, the mass content of inorganic compounds in the SEI film is also within a suitable range. This not only improves the strength of the SEI film but also keeps the thickness of the SEI film layer within a suitable range, thereby reducing the initial DC resistance of the battery cell and the rate of increase of DC resistance during cycling.

[0094] In some embodiments, the electrolyte further includes lithium salt and organic solvent.

[0095] In some embodiments, the lithium salt may be selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0096] In some embodiments, the organic solvent may be selected from at least one of dimethyl carbonate (DMC), ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), propylene carbonate (PC), methyl propyl carbonate (MPC), γ-butyrolactone (GBL), ethyl acetate (EA), tetrahydrofuran (THF), fluorobenzene (FB), and acetonitrile (AN).

[0097] Positive electrode sheet

[0098] The positive electrode includes a positive current collector and a positive electrode film layer disposed on at least one side of the positive current collector, the positive electrode film layer including a positive active material.

[0099] The positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on one or both of the two opposite surfaces of the positive current collector.

[0100] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0101] In some embodiments, the positive electrode active material includes lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials; only one type may be used, or two or more types may be used in combination. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also known as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM211), LiNi 0.6 Co 0.2 Mn0.2 O2 (also known as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4). 4( It can also be abbreviated as LFP), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites, at least one of them.

[0102] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one selected from polyacrylic acid, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0103] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0104] In some embodiments, the positive electrode sheet can be prepared by dispersing the above-mentioned components for preparing the positive electrode sheet, such as positive active material, conductive agent, binder, lithium supplementer and any other components, in a solvent (e.g. N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto the positive electrode current collector, and then obtaining the positive electrode sheet after drying, cold pressing and other processes.

[0105] Negative electrode sheet

[0106] The negative electrode includes a negative current collector and a negative electrode film layer optionally disposed on at least one surface of the negative current collector. The negative electrode film layer includes a negative electrode active material.

[0107] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0108] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0109] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. The silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0110] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0111] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0112] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0113] In some embodiments, the negative electrode sheet can be prepared by dispersing the components used to prepare the negative electrode sheet, such as the negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto the negative electrode current collector, and then obtaining the negative electrode sheet after drying, cold pressing and other processes.

[0114] Separating membrane

[0115] In some embodiments, the secondary battery also includes a separator. This application does not impose any particular limitation on the type of separator; any known porous separator with good chemical and mechanical stability can be selected.

[0116] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation. In some embodiments, the separator may also have one or more coatings.

[0117] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0118] battery cell

[0119] In some implementations, the positive electrode, negative electrode, and separator can be fabricated into an electrode assembly using a winding or stacking process.

[0120] In some embodiments, the battery cell may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and electrolyte described above.

[0121] In some implementations, the outer packaging of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.

[0122] The outer packaging of a single battery cell can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0123] This application does not impose any particular restrictions on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape.

[0124] For example, Figure 1 The example shown is a square-structured battery cell 5.

[0125] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. The positive electrode, negative electrode, and separator 30 may be formed into an electrode assembly 52 through a winding or stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in a single battery cell 5 may be one or more, which can be selected by those skilled in the art according to specific practical needs.

[0126] The second aspect of this application provides a battery device, including the battery cell provided in the first aspect of this application, wherein the battery device is at least one of a battery module, a battery pack, and an energy storage device.

[0127] In some implementations, individual battery cells can be assembled into a battery module. The number of individual battery cells contained in a battery module can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery module.

[0128] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 3 In battery module 4, multiple battery cells 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other way.

[0129] Furthermore, the multiple battery cells 5 can be secured using fasteners. Optionally, the battery module 4 may also include a housing with a receiving space in which the multiple battery cells 5 are received.

[0130] In some embodiments, the battery modules described above can also be assembled into a battery pack, wherein the number of battery modules contained in the battery pack is...

[0131] There can be one or more, and the specific number can be selected by those skilled in the art based on the application and capacity of the battery pack.

[0132] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0133] In addition, this application also provides an electrical device, which includes at least one of the battery cell, battery module, or battery pack provided in this application. The battery cell, battery module, or battery pack can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0134] As the electrical equipment, battery cells, battery modules, or battery packs can be selected according to their usage requirements.

[0135] Figure 6 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density batteries, a battery pack or battery module can be used.

[0136] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0137] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0138] Example

[0139] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0140] I. Preparation Method

[0141] Example 1

[0142] 1) Electrolyte

[0143] In an argon-atmosphere glove box with a water content of <10 ppm, lithium bis(fluorosulfonyl)imide (LiFSI) was slowly added as the lithium salt using ethylene carbonate EC as the solvent and stirred thoroughly until completely dissolved. After returning to room temperature, 2% by mass of the first additive 1,3-propanedisulfonic anhydride and 1% by mass of the second additive ethylene sulfate relative to the total mass of the electrolyte were added sequentially, and the mixture was thoroughly mixed to obtain the electrolyte. Based on the total mass of the electrolyte, the lithium salt accounted for 10% of the total mass.

[0144] 2) Preparation of positive electrode sheet

[0145] The active material lithium iron phosphate, the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed thoroughly in an appropriate amount of NMP solvent system at a weight ratio of 97.5%:0.5%:2.0% to prepare a positive electrode slurry. The positive electrode slurry was coated on the positive electrode current collector aluminum foil, and then dried at 100°C, cold-pressed, and slit to obtain the positive electrode sheet.

[0146] 3) Preparation of negative electrode sheet

[0147] The active material graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are thoroughly mixed in an appropriate amount of deionized water solvent system at a weight ratio of 96.5%:0.7%:1.8%:1% to obtain a negative electrode slurry. The negative electrode slurry is then coated onto Cu foil, and after drying, cold pressing, and slitting, a negative electrode sheet is obtained.

[0148] 4) Separating membrane

[0149] Polyethylene porous polymer film is used as the separator.

[0150] 5) Preparation of battery cells

[0151] The positive electrode, separator, and negative electrode are stacked in sequence and wound to obtain the battery cell. The battery cell is then placed in an outer packaging, and the electrolyte is added. After processes such as encapsulation, settling, formation, and aging, a single battery cell is obtained.

[0152] Examples 2-7

[0153] Compared with Example 1, the mass content of 1,3-propanedisulfonic anhydride, the type and mass content of the second additive were adjusted in Examples 2-7, and a third additive, vinylene carbonate, with a mass content of 4% was added. The specific electrolyte formulations are shown in Table 1.

[0154] Comparative Example 1

[0155] Compared with Example 1, in Comparative Example 1, the second additive was replaced with vinyl ethylene sulfite. The specific electrolyte formulation is shown in Table 1.

[0156] Comparative Examples 2-3

[0157] Compared with Example 2, Comparative Examples 2-3 do not contain 1,3-propanedisulfonic anhydride or vinyl sulfate, respectively. The specific electrolyte formulations are shown in Table 1.

[0158] Comparative Example 4

[0159] Compared with Example 2, in Comparative Example 4, the second additive was replaced with vinyl ethylene sulfite. The specific electrolyte formulation is shown in Table 1.

[0160] Comparative Example 5

[0161] Compared with Example 4, in Comparative Example 5, the first additive was replaced with 1,3-propenesulfonate lactone. The specific electrolyte formulation is shown in Table 1.

[0162] II. Testing Methods

[0163] 1. Initial DC resistance of a single battery cell

[0164] Charge the battery cell to 3.8V at a rate of 0.33C, then discharge the battery cell to 20% SOC at a rate of 0.33C. Record the voltage at this time as U1. Let it stand for 30 minutes. Discharge it at a rate of 3.5C for 30 seconds and record the voltage at this time as U2. The DCR0 of the battery cell is (U1-U2) / I.

[0165] 2. Growth rate of DC resistance of individual battery cells

[0166] The initial DC internal resistance DCR0 of the battery cell was obtained using the above test method; after storage at 25°C for 75 days, the DCR1 of the battery cell was tested, and the growth rate of DCR was [(DCR1-DCR0) / DCR0]*100%.

[0167] III. Analysis of Test Results for Each Embodiment and Comparative Example

[0168] Battery cells for each embodiment and comparative example were prepared according to the above method, and various parameters were measured. The results are shown in the table below.

[0169] Table 1

[0170]

[0171]

[0172] As can be seen from the table above, the electrolyte of the battery cells in Examples 1-7 includes a first additive of 1,3-propanedisulfonic anhydride and a second additive of vinyl sulfate, 1,3-propenesulfonate lactone, or 1,3-propanesulfonate lactone, and the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.2V-1.5V.

[0173] As can be seen from the comparison between Example 1 and Comparative Example 1, and between Examples 2-7 and Comparative Examples 2-5, the electrolyte contains both a first additive and a second additive, and the first additive contains 1,3-propanedisulfonic anhydride. The first additive, relative to Li... + / Li reduction potential and the second additive relative to Li +The difference in reduction potential between Li and the cell is 0.2V-1.5V, which can reduce the DC resistance and DC resistance growth rate of the cell.

[0174] A comparison of Examples 2 and 4 with Example 3 shows that the difference between the reduction potential of the first additive relative to Li+ / Li and the reduction potential of the second additive relative to Li+ / Li is 0.3V-0.5V, which can reduce the DC impedance and DC impedance growth rate of the battery cell.

[0175] Examples 2 and 5-7 show that when the mass ratio of the first additive to the second additive is 10:1 to 1:1, the battery cell exhibits low DC resistance and low DC resistance growth rate. Comparing Examples 2 and 6-7 with Example 5, examples 5:1 to 1:1 in mass ratio of the first additive to the second additive can reduce the DC resistance growth rate of the battery cell.

[0176] As can be seen from the comparison between Example 2 and Example 1, the electrolyte containing the third additive of vinylene carbonate can reduce the DC impedance and DC impedance growth rate of the battery cell.

[0177] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, The electrolyte comprises a positive electrode, a negative electrode, and an electrolyte solution. The electrolyte solution includes a first additive and a second additive. The first additive includes a sulfonic anhydride compound, and the second additive includes one or more of a sulfate ester compound, a sulfite ester compound, and a sulfonate ester compound. Wherein the first additive is relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.2V-1.5V.

2. The battery cell according to claim 1, characterized in that, The first additive relative to Li + / Li reduction potential and the second additive relative to Li + The difference in reduction potential between / Li is 0.3V-0.5V.

3. The battery cell according to claim 1 or 2, characterized in that, The sulfonic anhydride compounds relative to Li + The reduction potential of Li is 1.2V-1.6V, and / or, The sulfate ester compounds relative to Li + The reduction potential of Li is 1.1V-1.9V, and / or, The sulfite compounds relative to Li + The reduction potential of Li is 1.7V-2.1V, and / or, The sulfonate compounds relative to Li + The reduction potential of / Li is 0.8V-1.8V.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The first additive relative to Li + The reduction potential of / Li is greater than that of the second additive relative to Li. + The reduction potential of / Li, wherein the mass ratio of the first additive to the second additive is 10:1-1:1; Alternatively, the first additive relative to Li + The reduction potential of / Li is lower than that of the second additive relative to Li. + The reduction potential of / Li, and the mass ratio of the second additive to the first additive is 10:1-1:

1.

5. The battery cell according to any one of claims 1 to 3, characterized in that, The first additive relative to Li + The reduction potential of / Li is greater than that of the second additive relative to Li. + The reduction potential of / Li, wherein the mass ratio of the first additive to the second additive is 5:1-1:1; Alternatively, the first additive relative to Li + The reduction potential of / Li is lower than that of the second additive relative to Li. + The reduction potential of / Li, and the mass ratio of the second additive to the first additive is 5:1-1:

1.

6. The battery cell according to any one of claims 1 to 5, characterized in that, Based on the mass of the electrolyte, the mass content of the first additive is 0.01%-10%; and / or, The mass content of the second additive is 0.01%-10%.

7. The battery cell according to any one of claims 1 to 5, characterized in that, Based on the mass of the electrolyte, the mass content of the first additive is 0.01%-5%; and / or, The mass content of the second additive is 0.01%-5%.

8. The battery cell according to any one of claims 1 to 7, characterized in that, The sulfonic anhydride compounds include one or more of the following compounds. And / or, the sulfate ester compounds include one or more of vinyl sulfate (DTD), ethylene disulfate (2-DTD), ethylene trisulfate (3-DTD), 4-methyl vinyl sulfate, 4-ethyl vinyl sulfate, 4-propyl vinyl sulfate, 4-butyl vinyl sulfate, and their derivatives. And / or, the sulfite compounds include one or more of vinyl sulfite (ES), vinyl vinyl sulfite (VES), butylene sulfite (BS), propylene sulfite (TMS), and their derivatives. And / or, the sulfonate compounds include one or more of 1,3-propanesulfonate lactone (PS), 1,3-propenesulfonate lactone (PES), 1,4-butanesulfonate lactone (1,4-BS), methylene disulfonate (MMDS), and their derivatives.

9. The battery cell according to any one of claims 1 to 8, characterized in that, The electrolyte also includes a third additive, which comprises carbonate compounds, including one or more of vinylene carbonate (VC), fluoroethylene carbonate (FEC), and vinyl ethylene carbonate (VEC).

10. The battery cell according to claim 9, characterized in that, The ratio of the mass of the third additive to the combined mass of the first and second additives is 0.5:1 to 5:

1.

11. The battery cell according to claim 9, characterized in that, The mass ratio of the third additive to the sum of the masses of the first and second additives is 1.1:1 to 2:

1.

12. The battery cell according to any one of claims 9 to 11, characterized in that, Based on the mass of the electrolyte, the mass content of the third additive is 0.01%-10%.

13. The battery cell according to any one of claims 9 to 11, characterized in that, Based on the mass of the electrolyte, the mass content of the third additive is 3%-6%.

14. A battery device, characterized in that, The battery device includes the battery cell of any one of claims 1 to 13, and the battery device includes at least one of battery module, battery pack, and energy storage battery.

15. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1 to 13.

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