Battery monomer, battery device and power utilization device

Abstract

The invention relates to a battery monomer, a battery device and a power utilization device. The battery monomer comprises a positive pole piece, a separator, an electrolyte and a negative pole piece, at least one of the positive pole piece, the separator, the electrolyte and the negative pole piece contains an additive; the additive is selected from small organic molecules, organic polymers or organic salts with S = C (R)-S functional groups; wherein R is hydrogen, a substituted or unsubstituted straight chain or branched chain alkyl group, an alkoxy alkyl group, an aryl group, a heteroaryl group or a cycloalkyl group; or R and sulfur atoms in the carbon-sulfur single bond form substituted or unsubstituted saturated or unsaturated cycloalkyl. By applying the additive, the effect of chelating transition metal ions is achieved, the negative effect caused by dissolution of transition metal is reduced, and the capacity retention ratio of the battery under circulation and storage conditions is improved.

Description

Technical Field

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

[0002] Secondary batteries, represented by lithium-ion batteries, are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. The application of secondary batteries has placed higher demands on their performance.

[0003] When a secondary battery uses a positive electrode active material containing transition metal oxides, the transition metals can easily shuttle to the negative electrode during charging and discharging, and be reduced on the surface of the negative electrode. This can lead to adverse reactions such as SEI film breakage and reconstruction, and further degrade battery performance. Summary of the Invention

[0004] The purpose of this application is to provide a battery cell, a battery device, and an electrical device. The battery cell uses an additive with an S=C(R)-S functional group to chelate transition metal ions, thereby reducing the negative effects of transition metal dissolution and improving the capacity retention rate of the battery under cycling and storage conditions.

[0005] Therefore, this application provides a battery cell, which includes a positive electrode, a separator, an electrolyte, and a negative electrode;

[0006] At least one of the positive electrode, the separator, the electrolyte, and the negative electrode contains an additive; the additive is selected from small organic molecules, organic polymers, or organic salts having S=C(R)-S functional groups;

[0007] Wherein, R is hydrogen, a substituted or unsubstituted straight-chain or branched alkyl, alkoxyalkyl, aryl, heteroaryl, or cycloalkyl; or, R together with the sulfur atom in the carbon-sulfur single bond forms a substituted or unsubstituted saturated or unsaturated cycloalkyl.

[0008] Compared to other elements used for chelating transition metals (such as nitrogen), sulfur has a larger charge radius, a stronger ability to adsorb transition metals, and better oxidation resistance. In this embodiment, an additive with an S=C(R)-S functional group is used. In this additive, a carbon-sulfur double bond and a carbon-sulfur single bond are simultaneously present on the same carbon atom. This functional group can form a 4-coordinated disulfide chelate structure with transition metal ions. Therefore, by applying the above-mentioned additive to at least one of the positive electrode, separator, electrolyte, and negative electrode of the battery cell, transition metal ions can be significantly and effectively chelated. This helps to eliminate or reduce adverse reactions caused by transition metal ion shuttle, thereby optimizing the battery's capacity retention under cycling and storage conditions.

[0009] In some embodiments, the additive is a small organic molecule having the S=C(R)-S functional group;

[0010] Wherein, R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl;

[0011] Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

[0012] In some embodiments, the additive is an organic polymer having an S=C(R)-S functional group;

[0013] The organic polymer has polyacrylic acid as its main chain; and / or the weight-average molecular weight of the organic polymer is 5,000 to 100,000.

[0014] In some embodiments, the additive is an organic salt having an S=C(R)-S functional group;

[0015] The organic salt contains a metal cation M, wherein M is selected from lithium ions, sodium ions, potassium ions, and zinc ions; and / or,

[0016] The R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl;

[0017] Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

[0018] When the above-mentioned small organic molecules, organic polymers or organic salts are used as additives, they are more compatible with the battery system and, without negatively affecting the battery function, are conducive to further improving the chelation effect on transition metals.

[0019] In some embodiments, the substitution refers to the replacement of hydrogen or carbon in R by at least one of nitrogen, oxygen, or sulfur.

[0020] When the additive also contains nitrogen, oxygen atoms or additional sulfur atoms, it helps to increase the number of sites that can complex with transition metals, more effectively chelate transition metal ions, and reduce undesirable interfacial reactions.

[0021] In some embodiments, the additive is selected from at least one of the following groups:

[0022]

[0023]

[0024] In some embodiments, the positive electrode sheet includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector; the positive electrode material layer contains a positive electrode active material and the additive, wherein the additive accounts for 0.3% to 1% of the mass percentage of the positive electrode material layer.

[0025] When the positive electrode contains the additives, keeping the additive content within the above range allows for a more thorough chelation effect on dissolved transition metals while avoiding negative impacts on the battery's DC internal resistance (DCR), which is beneficial for improving the battery's cycle and storage performance.

[0026] In some embodiments, the particle size Dv50 of the additive is less than or equal to the particle size Dv50 of the positive electrode active material.

[0027] Depending on the preparation process (e.g., dry mixing, wet mixing) and the different solubilities of the additives in the corresponding solvents, the additives may appear as irregular lumps or particles in the battery. In some embodiments, the additives may be dissolved in the corresponding solvent beforehand and uniformly dispersed on the surface of the positive electrode sheet; in some embodiments, if a dry mixing preparation process is used or the additives are insoluble in the solvent, the additives will still be in particulate form in the battery cell. When the particle size Dv50 is less than or equal to the particle size Dv50 of the positive electrode active material, it is beneficial for the additives to be uniformly mixed with the positive electrode active material and uniformly dispersed on the surface of the positive electrode sheet.

[0028] In some embodiments, the positive electrode material layer contains a positive electrode active material, which includes at least one of a high-nickel positive electrode material and a lithium manganese iron phosphate positive electrode material.

[0029] The chemical formula of the high-nickel cathode material is Li. 1+a [Ni x Co y Mn z M1 bO2, where 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, and M1 is one or more of Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo and B;

[0030] The chemical formula of the lithium manganese iron phosphate cathode material is (LiMn) p Fe 1-p-q M2 q PO4), where 0.1≤p≤0.9, q≤0.05, and M2 is one or more of V, Ti, Mg, Ni, and Fe.

[0031] The battery cell provided in this application, when using a positive electrode active material with a high transition metal content, can also effectively reduce the adverse effects of transition metal dissolution through the chelating effect of additives. Therefore, the battery cell provided in this application, when using the aforementioned positive electrode active material, can simultaneously possess the advantages of high energy density and long cycle / storage life.

[0032] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer containing the additive; the additive accounts for 0.2% to 1.0% of the mass percentage of the negative electrode material layer.

[0033] In the embodiments of this application, the additive is disposed on the surface of the negative electrode sheet, which can chelate the transition metal reaching the negative electrode sheet and minimize its reduction on the negative electrode surface. When the additive is used in the negative electrode sheet, the above-mentioned mass ratio is more conducive to chelating the transition metal before it is reduced, thus avoiding its adverse effects on the SEI film.

[0034] In some embodiments, the separator includes the additive, the separator comprising a base film and a film layer disposed on at least one surface of the base film, the film layer containing the additive; the additive constitutes 2-5 mg / 50*100 mm of the film layer. 2 .

[0035] When additives are placed on separators, they can chelate transition metals that dissolve from the positive electrode into the electrolyte, thus acting as an interceptor. When additives are used in separators, using the above-mentioned mass percentage is more conducive to their chelation of transition metals in the electrolyte, thereby greatly preventing transition metals from shuttling to the negative electrode surface.

[0036] In some embodiments, the electrolyte includes the additive; the additive accounts for 0.5% to 5% of the electrolyte by mass.

[0037] A second aspect of this application provides a battery device comprising the battery cell described in the first aspect of this application.

[0038] A third aspect of this application provides an electrical device comprising a single battery cell as described in the first aspect of this application or a battery device as described in the second aspect of this application.

[0039] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application, it can be implemented according to the contents of the specification. In order to make the above and other objects, features and advantages of this application more obvious and understandable, the specific implementation methods of this application are listed below. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. In the drawings:

[0041] Figure 1 This is a schematic diagram of a battery cell according to one embodiment of this application;

[0042] Figure 2 yes Figure 1 An exploded view of a battery cell according to one embodiment of this application is shown.

[0043] Figure 3 This is a schematic diagram of a battery module according to one embodiment of this application;

[0044] Figure 4 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0045] Figure 5 yes Figure 4 An exploded view of a battery pack according to one embodiment of this application is shown;

[0046] Figure 6 This is a schematic diagram of an electrical device in which a single battery cell is used as a power source according to one embodiment of this application;

[0047] Figure 7 These are the ion concentration detection results of the positive electrode sheets of Example 1 and Comparative Example 1 of this application after immersion experiments;

[0048] Figure 8 This is a comparison chart of the cycle capacity retention test results of lithium-ion batteries in Example 1 and Comparative Example 1 of this application; where green represents the battery of Example 1 and blue represents the battery of Comparative Example 1.

[0049] Figure 9This is a comparison chart of the lithium-ion battery storage capacity retention test results of Example 1 and Comparative Example 1 of this application; where green represents the battery of Example 1 and blue represents the battery of Comparative Example 1.

[0050] Explanation of reference numerals in the attached figures:

[0051] 1 Battery pack; 2 Upper housing; 3 Lower housing; 4 Battery module; 5 Battery cell; 51 Casing; 52 Electrode assembly; 53 End cap. Detailed Implementation

[0052] Exemplary embodiments of this disclosure will now be described in more detail. It should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0053] 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 also expected that ranges of 60–110 and 80–120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​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 "a–b" 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.

[0054] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0055] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0056] Unless otherwise specified, all steps of 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.

[0057] 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.

[0058] Secondary batteries, represented by lithium-ion batteries, have been widely used. When secondary batteries use positive electrode active materials containing transition metal oxides, the transition metals can easily shuttle to the negative electrode during charging and discharging, and be reduced on the surface of the negative electrode. This may cause adverse reactions such as SEI film breakage and reconstruction, and further degrade battery performance.

[0059] This application utilizes an additive containing the S=C(R)-S functional group in at least one of the positive electrode, separator, electrolyte, and negative electrode of a battery cell to achieve a chelating effect on transition metals, thereby reducing the adverse effects of free transition metals and improving battery performance.

[0060] The solutions described in the embodiments of this application are applicable to battery cells, battery devices using battery cells, and electrical devices using at least one of battery cells and battery devices.

[0061] Battery cell

[0062] In this embodiment of the application, the battery cell can be a secondary battery, which refers to a battery cell that can be recharged to activate the active materials and continue to be used after the battery cell has been discharged.

[0063] The battery cell can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc. In some embodiments, the battery cell is a lithium-ion battery.

[0064] [Electrode Assembly]

[0065] A single battery cell typically includes an electrode assembly. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator positioned between the positive and negative electrodes. During the charging and discharging process of a single battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through.

[0066] In some embodiments, a battery cell is provided, including a positive electrode, a separator, an electrolyte, and a negative electrode;

[0067] At least one of the positive electrode, the separator, the electrolyte, and the negative electrode contains an additive; the additive is selected from small organic molecules, organic polymers, or organic salts having S=C(R)-S functional groups;

[0068] Wherein, R is hydrogen, a substituted or unsubstituted straight-chain or branched alkyl, alkoxyalkyl, aryl, heteroaryl, or cycloalkyl; or, R together with the sulfur atom in the carbon-sulfur single bond forms a substituted or unsubstituted saturated or unsaturated cycloalkyl.

[0069] Existing technologies often utilize nitrogen to chelate transition metals. Due to nitrogen's electronegativity, it interacts with transition metal ions to form a multidentate chelate structure, which can alleviate the problem of transition metal dissolution to some extent. However, nitrogen-based chelates have poor oxidation resistance and are only suitable for use in separators. Compared to nitrogen and other elements used for chelating transition metals, sulfur has a larger charge radius, a stronger ability to adsorb transition metals, and better oxidation resistance, making it suitable for direct application on the surface of positive electrode sheets. In the embodiments of this application, an additive with an S=C(R)-S functional group is used. In this additive, a carbon-sulfur double bond and a carbon-sulfur single bond are simultaneously present on the same carbon atom. Therefore, this functional group can form a 4-coordinate disulfide chelate structure with transition metal ions.

[0070]

[0071] Therefore, by applying the above-mentioned additives to at least one of the positive electrode, separator, electrolyte and negative electrode of the battery cell, transition metal ions can be significantly and effectively chelated, thereby helping to eliminate or reduce adverse reactions caused by transition metal ion shuttle, and achieving the effect of optimizing the capacity retention rate of the battery under cycle and storage conditions.

[0072] The S=C(R)-S functional group refers to a functional group in which two sulfur atoms are attached to the same carbon atom to form both a carbon-sulfur double bond and a carbon-sulfur single bond. An R atom can also be attached to this carbon atom. Based on the principle of chelating transition metal ions by additives, the chelating effect is mainly exerted by S=CS. Therefore, the structure of R can be arbitrarily chosen from the following ranges: R is hydrogen, a substituted or unsubstituted straight-chain or branched alkyl group, an alkoxyalkyl group, an aryl group, a heteroaryl group, or a cycloalkyl group; or, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated cycloalkyl group.

[0073] In some embodiments, the additive is a small organic molecule having the S=C(R)-S functional group;

[0074] Wherein, R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl;

[0075] Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

[0076] In some embodiments, the additive is a small organic molecule having an S=C(R)-S structure. Wherein, R is hydrogen, a substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl.

[0077] Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

[0078] In some embodiments, the organic small molecule includes at least one selected from the group consisting of:

[0079]

[0080]

[0081] In some embodiments, the additive is an organic polymer having an S=C(R)-S functional group;

[0082] The organic polymer has polyacrylic acid as its main chain and a weight-average molecular weight of 5,000-100,000.

[0083] In some embodiments, the organic polymer comprises at least one selected from the group consisting of:

[0084]

[0085] Wherein, M is a metal cation, and M is selected from lithium ions (Li...+ Sodium ions (Na) + ), potassium ions (K) + ), zinc ions (Zn) 2+ ), ammonium ions (NH4) + ).

[0086] In some embodiments, the additive is an organic salt having an S=C(R)-S functional group;

[0087] The organic salt contains a metal cation M, wherein M is selected from lithium ions (Li₂). + Sodium ions (Na) + ), potassium ions (K) + ), zinc ions (Zn) 2+ ), ammonium ions (NH4) + ); and / or,

[0088] The R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl;

[0089] Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

[0090] In some embodiments, the organic salt comprises at least one selected from the group consisting of:

[0091] In this context, M is selected from lithium ion (Li... + Sodium ions (Na) + ), potassium ions (K) + ), zinc ions (Zn) 2+ ), ammonium ions (NH4) + ).

[0092] When the above-mentioned small organic molecules, organic polymers or organic salts are used as additives, they are more compatible with the battery system and, without negatively affecting the battery function, are conducive to further improving the chelation effect on transition metals.

[0093] In some embodiments, the substitution refers to the replacement of hydrogen or carbon in R by at least one of nitrogen, oxygen, or sulfur.

[0094] When the additive also contains nitrogen, oxygen atoms or additional sulfur atoms, it helps to increase the number of sites that can complex with transition metals, more effectively chelate transition metal ions, and reduce undesirable interfacial reactions.

[0095] [Positive electrode plate]

[0096] In some embodiments, the positive electrode includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector; the positive electrode material layer contains a positive electrode active material and the additive, wherein the additive accounts for 0.3% to 1% of the mass percentage of the positive electrode material layer; for example, the mass percentage of the additive in the positive electrode material layer may be selected from about 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, etc.

[0097] When the positive electrode contains the additives, keeping the additive content within the above range allows for a more thorough chelation effect on dissolved transition metals, while avoiding negative impacts on the battery's DC internal resistance (DCR), thus improving the battery's cycle and storage performance.

[0098] In some embodiments, the particle size Dv50 of the additive is less than or equal to the particle size Dv50 of the positive electrode active material.

[0099] Depending on the preparation process (e.g., dry mixing, wet mixing) and the different solubilities of the additives in the corresponding solvents, the additives may appear as irregular lumps or particles in the battery. In some embodiments, the additives may be dissolved in the corresponding solvent beforehand and uniformly dispersed on the surface of the positive electrode sheet; in some embodiments, if a dry mixing preparation process is used or the additives are insoluble in the solvent, the additives will still be in particulate form in the battery cell. When the particle size Dv50 is less than or equal to the particle size Dv50 of the positive electrode active material, it is beneficial for the additives to be uniformly mixed with the positive electrode active material and uniformly dispersed on the surface of the positive electrode sheet.

[0100] In some embodiments, the positive electrode material layer contains a positive electrode active material, which includes at least one of a high-nickel positive electrode material and a lithium manganese iron phosphate positive electrode material.

[0101] The chemical formula of the high-nickel cathode material is Li. 1+a [Ni x Co y Mn z M1 b O2, where 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, and M1 is one or more of Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo and B;

[0102] The chemical formula of the lithium manganese iron phosphate cathode material is (LiMn) p Fe 1-p-q M2 qPO4), where 0.1≤p≤0.9, q≤0.05, and M2 is one or more of V, Ti, Mg, Ni, and Fe.

[0103] The battery cell provided in this application, when using a positive electrode active material with a high transition metal content, can also effectively reduce the adverse effects of transition metal dissolution through the chelating effect of additives. Therefore, the battery cell provided in this application, when using the aforementioned positive electrode active material, can simultaneously possess the advantages of high energy density and long cycle / storage life.

[0104] In some embodiments, the positive electrode active material is a high-nickel positive electrode material with a particle size Dv50 of 2-15 μm; for example, when the high-nickel positive electrode material can be polycrystalline particles, single-crystal particles, or a mixture of both, the particle size Dv50 of the polycrystalline particles is 8-12 μm, and the particle size Dv50 of the single-crystal particles is 2-5 μm. In some embodiments, the positive electrode active material is a lithium manganese iron phosphate positive electrode material with a particle size Dv50 of, for example, 0.3-2 μm.

[0105] In some embodiments, the positive electrode active material may include other positive electrode active materials for lithium-ion batteries known in the art. As an example, the positive electrode active material may include at least one of the following: lithium transition metal oxides, such as lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and modified compounds thereof; olivine-structured lithium phosphates, such as lithium iron phosphate (e.g., LiFePO4 (also abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0106] In some embodiments, the positive electrode material layer may optionally include a binder. For example, the binder may include one or more combinations selected from the group consisting of: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0107] In some embodiments, the positive electrode material layer may optionally include a conductive agent. For example, the conductive agent may include one or more combinations selected from the group consisting of: Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0108] 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.).

[0109] Positive electrode sheets can be prepared by dry mixing or wet mixing. In some embodiments, positive electrode sheets can be prepared by the following method (wet mixing): dispersing the components of the above-mentioned positive electrode material layer, such as the positive electrode active material, the additives, optional conductive agents, optional binders, and any other components in a solvent (e.g., N-methylpyrrolidone), to form a positive electrode slurry; coating the positive electrode slurry onto a positive electrode current collector, and obtaining the positive electrode sheet after drying, cold pressing, and other processes.

[0110] In some embodiments, the positive electrode sheet can be prepared by the following method (dry mixing): the components of the above-mentioned positive electrode material layer, such as the positive electrode active material, the additive, optional conductive agent, optional binder and any other components, are mixed evenly, and then an appropriate amount of solvent (e.g., N-methylpyrrolidone) is added and stirred evenly to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0111] [Negative electrode plate]

[0112] In some embodiments, the negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, the negative electrode material layer containing the additive; the additive accounts for 0.2% to 1.0% of the mass percentage of the negative electrode material layer; for example, it can be about 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0113] In the embodiments of this application, the additive is disposed on the surface of the negative electrode sheet, which can chelate the transition metal reaching the negative electrode sheet and minimize its reduction on the negative electrode surface. When the additive is used in the negative electrode sheet, the above-mentioned mass ratio is more conducive to chelating the transition metal before it is reduced, thus avoiding its adverse effects on the SEI film.

[0114] 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 material substrate and a metal layer formed on at least one surface of the polymer material 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In some embodiments, the negative electrode material layer includes a negative electrode active material, which may be a negative electrode active material known in the art for use in batteries. For example, the negative electrode active material includes one or more combinations selected from the group consisting of: natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, TiO2-Li4Ti5O 12 Li-Al alloys are used. However, this invention is not limited to these materials; other conventional materials that can be used as negative electrode active materials for lithium-ion batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0116] In some embodiments, the negative electrode material layer may optionally include a binder. For example, the binder may include one or more combinations selected from the group consisting 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).

[0117] In some embodiments, the negative electrode material layer may optionally include a conductive agent. For example, the conductive agent may include one or more combinations selected from the group consisting of: Super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0118] In some embodiments, the negative electrode material layer may also optionally include other additives. For example, other additives may be thickeners (such as sodium carboxymethyl cellulose (CMC-Na)).

[0119] The negative electrode sheet can be prepared by dry mixing or wet mixing. In some embodiments, the negative electrode sheet can be prepared by the following method (wet mixing): dispersing the components of the above-mentioned negative electrode material layer, such as the negative electrode active material, the additives, optional conductive agents, optional binders, 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.

[0120] In some embodiments, the negative electrode sheet can be prepared by the following method (dry mixing): the components of the above-mentioned negative electrode material layer, such as the negative electrode active material, the additive, optional conductive agent, optional binder and any other components, are mixed evenly, and then an appropriate amount of solvent (e.g., deionized water) is added and stirred evenly to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0121] [Isolation Component]

[0122] In some embodiments, the separator includes a base film and a film layer disposed on at least one surface of the base film, the film layer containing the additive; the additive accounts for 2-5 mg / 50*100 mm of the film layer. 2 .

[0123] When additives are placed on separators, they can chelate transition metals that dissolve from the positive electrode into the electrolyte, thus acting as an interceptor. When additives are used in separators, using the above-mentioned mass percentage is more conducive to their chelation of transition metals in the electrolyte, thereby greatly preventing transition metals from shuttling to the negative electrode surface.

[0124] The additive can be applied to the separator by coating and drying. Specifically, a slurry containing the additive is coated onto the base film of the separator, and the separator is prepared after drying and other processes.

[0125] This application does not impose any particular restrictions on the base membrane used as the separator; any known porous structure base membrane with electrochemical and mechanical stability can be selected according to actual needs. For example, the base membrane can be a single-layer or multi-layer film containing one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0126] [Electrolytes]

[0127] The electrolyte acts as a conductor of ions between the positive and negative electrode plates. The electrolyte includes the additive; the additive constitutes 0.5% to 5% of the electrolyte by mass; for example, it can be about 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0128] This application does not impose specific restrictions on the type of electrolyte; it can be selected according to requirements. The electrolyte can be liquid, gel, or solid.

[0129] Liquid electrolytes include electrolyte salts and solvents.

[0130] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0131] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone. The solvent may also be an ether solvent. Ether solvents may include one or more of ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyl tetrahydrofuran, diphenyl ether, and crown ethers.

[0132] In some embodiments, the electrolyte may optionally include other functional additives. For example, the other functional additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain properties of the battery cell, such as additives that improve the overcharge / fast charge performance of the battery cell, additives that improve the high-temperature performance of the battery cell, and additives that improve the low-temperature performance of the battery cell.

[0133] The gel electrolyte includes a polymer as a backbone network and can be used in conjunction with an ionic liquid—lithium salt.

[0134] Solid electrolytes include polymer solid electrolytes, inorganic solid electrolytes, and composite solid electrolytes.

[0135] As an example, the polymers of polymeric solid electrolytes may include polyethers (polyoxyethylene), polysiloxanes, polycarbonates, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, monoionic polymers, polyionic liquids, cellulose, etc.

[0136] As an example, inorganic solid electrolytes can be one or more of the following: oxide solid electrolytes (crystalline perovskite, sodium superconducting ion conductor, garnet, amorphous LiPON thin film), sulfide solid electrolytes (crystalline lithium superconducting ion conductor (lithium-germanium-phosphorus-sulfur, sulfosilium-germanium), amorphous sulfides), halide solid electrolytes, nitride solid electrolytes, and hydride solid electrolytes.

[0137] As an example, composite solid electrolytes are formed by adding inorganic solid electrolyte fillers to polymer solid electrolytes.

[0138] [Structure of the electrode assembly]

[0139] The electrode assembly can be a wound structure, a stacked structure, or a hybrid structure of wound and stacked.

[0140] In some implementations, the electrode assembly is a wound structure. The positive and negative electrode sheets are wound into a wound structure.

[0141] In some implementations, the electrode assembly is a stacked structure.

[0142] As an example, multiple positive and negative electrode plates can be set, and multiple positive and multiple negative electrode plates can be stacked alternately.

[0143] As an example, multiple positive electrode sheets can be set, and negative electrode sheets are folded to form multiple stacked folded segments, with a positive electrode sheet sandwiched between adjacent folded segments.

[0144] As an example, both the positive and negative electrode sheets are folded to form multiple stacked folded segments.

[0145] As an example, multiple separators can be provided, each positioned between any adjacent positive or negative electrode plates.

[0146] As an example, the separator can be continuously arranged between any adjacent positive or negative electrode plates by folding or rolling.

[0147] In some embodiments, the electrode assembly can be cylindrical, flat, or polygonal, etc.

[0148] In some embodiments, the electrode assembly is provided with tabs that allow current to be drawn from the electrode assembly. The tabs include a positive tab and a negative tab.

[0149] [shell]

[0150] In some embodiments, the battery cell may include a casing. The casing may be a steel casing, an aluminum casing, a plastic casing (such as a polypropylene casing), a composite metal casing (such as a copper-aluminum composite casing), or an aluminum-plastic film, etc. In some embodiments, the casing may be a sealed structure or a non-sealed structure. As an example, when the casing is a non-sealed structure, the casing serves to protect the electrode assembly, and a sealing bag is included between the casing and the electrode assembly to encapsulate the electrode assembly and electrolyte. Specifically, the sealing bag may be a bag-shaped insulating component or an aluminum-plastic film. When the casing is a sealed structure, it is used to encapsulate components such as the electrode assembly and electrolyte.

[0151] As an example, the battery cell can be a cylindrical battery cell, a prismatic battery cell, a pouch battery cell, or a battery cell of other shapes. Prismatic battery cells include prismatic battery cells, blade-shaped battery cells, and multi-prismatic batteries, such as hexagonal prismatic batteries. This application does not impose any particular limitations. For example, Figure 1 This is an example of a square-shell battery cell 5.

[0152] In some implementations, refer to Figure 2 The outer casing includes an end cap 53 and a housing 51. The housing 51 has an opening, and the end cap 53 covers the opening. The housing 51 may have one or more openings. The end cap 53 may also have one or more. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within a receiving cavity formed by the housing 51 and the end cap 53. The electrolyte is immersed in the electrode assembly 52.

[0153] [Electrode terminals]

[0154] In some embodiments, at least one electrode terminal is provided on the housing, and the electrode terminal is electrically connected to the tab. The electrode terminal can be directly connected to the tab, or it can be indirectly connected to the tab through a current collector. The electrode terminal can be provided on the end cap or on the housing.

[0155] [Pressure relief mechanism]

[0156] In some embodiments, a pressure relief mechanism is provided on the casing. The pressure relief mechanism is used to release the internal gas of the battery cell.

[0157] As an example, the internal pressure or temperature of a battery cell is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell reaches the predetermined threshold, the pressure relief mechanism is activated or a weak structure in the pressure relief mechanism is broken, thereby forming an opening or channel for the internal pressure or temperature to be released. The threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell.

[0158] As an example, the pressure relief mechanism can be integrally molded with the housing.

[0159] As an example, the pressure relief mechanism can also be separately installed and connected to the housing.

[0160] The term "actuation" as used in this application refers to the activation or actuation of the pressure relief mechanism to a certain state, thereby releasing the internal pressure and temperature of the battery cell. The actions of the pressure relief mechanism may include, but are not limited to: movement of components within the mechanism to form an exhaust channel, rupture, breakage, tearing, or opening of at least a portion of the mechanism, etc. When the pressure relief mechanism is activated, the high-temperature, high-pressure substances inside the battery cell are discharged as waste from the activated portion. This method allows for pressure and temperature relief of the battery cell under controllable pressure or temperature, thereby preventing potentially more serious accidents.

[0161] In some embodiments, when the housing is a non-sealed structure, the pressure relief mechanism can be configured as a through hole for venting gas inside the battery cell.

[0162] The emissions from battery cells mentioned in this application include, but are not limited to: electrolyte, dissolved or split positive and negative electrode plates, fragments of separators, high-temperature and high-pressure gases generated by the reaction, flames, etc.

[0163] Battery device

[0164] The battery apparatus mentioned in the embodiments of this application may include one or more battery cell assemblies for providing voltage and capacity. A battery cell assembly may include multiple battery cells connected in series, parallel, or mixed connections via a busbar.

[0165] In some embodiments, a battery cell assembly is typically formed by arranging multiple battery cells.

[0166] As an example, a battery cell assembly can be a battery module, which is formed by arranging and fixing multiple battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple battery cells together with cable ties. Figure 3 This is battery module 4 as an example. (See reference...) Figure 3 In the battery module 4, multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other way.

[0167] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more individual battery cells housed within the housing.

[0168] As an example, the battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing. 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 housing and multiple battery modules 4 disposed within the housing. The housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 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 pack.

[0169] As an example, battery cell assemblies can also be housed in a housing by directly fixing multiple battery cells to the housing.

[0170] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the individual battery cells. Here, "closed" refers to covering or closing, and can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0171] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual battery cells.

[0172] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0173] Electric device

[0174] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use individual battery cells, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles, ships, and spacecraft. For example, spacecraft include airplanes, rockets, space shuttles, and spacecraft. Figure 6 This is an example of an electrical device. The electrical device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc.

[0175] Example 1

[0176] This embodiment provides a lithium-ion secondary battery, the preparation method of which is as follows:

[0177] (1) Positive electrode plate

[0178] LiNi will be used as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (particle size Dv50 of 8 μm), tetraethyl thiuram disulfide (particle size Dv50 of 6 μm) as an additive, polyvinylidene fluoride (PVDF) as a binder, and acetylene black as a conductive agent are dispersed in the solvent N-methylpyrrolidone (NMP) at a mass ratio of 98:0.5:1:0.5. After thorough mixing, a positive electrode slurry is obtained. The positive electrode slurry is then uniformly coated onto a positive electrode current collector, followed by drying, cold pressing, and slitting to obtain the positive electrode sheet.

[0179] (2) Negative electrode plate

[0180] Artificial graphite (particle size Dv50 of 15μm) as the negative electrode active material, acetylene black as the conductive agent, styrene-butadiene rubber (SBR) as the binder, and sodium carboxymethyl cellulose (CMC) as the thickener were dissolved in deionized water at a mass ratio of 97:0.5:1.5:1 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was then uniformly coated onto a copper foil as a negative electrode current collector, dried, and a negative electrode film was obtained. The film was then cold-pressed and slit to obtain a negative electrode sheet.

[0181] (3) Preparation of electrolyte

[0182] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), 1 mol / L LiPF6 was dissolved in an organic solvent (EC / DMC / EMC = 1 / 1 / 1) and stirred until homogeneous to obtain the corresponding electrolyte.

[0183] (4) Preparation of the isolation membrane: conventional polypropylene membrane is used as the isolation membrane.

[0184] (5) Preparation of lithium-ion batteries

[0185] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The electrode assembly is then wound up to obtain the electrode assembly. The electrode assembly is placed in the battery casing, dried, and then injected with electrolyte. The lithium-ion battery is then produced through processes such as vacuum sealing, settling, formation, and shaping.

[0186] Perform the following tests and record the results in Table 1.

[0187] 1. Immersion test of electrode sheets

[0188] Take 2g of the above positive electrode sheet and immerse it in 20mL of electrolyte + 20μL of H2O. Let it stand at 25℃ for 7 days. Then, take the electrolyte and perform inductively coupled plasma (ICP) testing to detect the content of transition metal Ni ions, Co ions, and Mn ions in the electrolyte as follows: Figure 7 As shown.

[0189] 2. Cyclic capacity retention test

[0190] Place the lithium-ion battery in the electrochemical test channel, cycle it for 1000 times at a 0.5C rate current and a charge / discharge voltage range of 2.8–5.25V at room temperature (25°C), and read the capacity value C1000. Compare this value with the initial first-cycle capacity C1. The cycle capacity retention rate can be obtained using the formula: Capacity retention rate = C1000 / C1 × 100%.

[0191] 3. Storage capacity retention test

[0192] Place the lithium-ion battery in the electrochemical test channel at 60°C and fully charge it at a 0.5C rate within the charge / discharge voltage range of 2.8–5.25V. Then fully discharge it and record the capacity C0. Hold the battery for 20 days and perform a full charge / discharge test under the same conditions as when the capacity C0 was tested, and record the capacity C1. Then hold the battery for another 20 days and perform a full charge / discharge test and record the capacity C2. Repeat the above steps to read the discharge capacity from C0 to C3. The storage capacity retention rate after 60 days can be calculated using the formula: Capacity retention rate = C3 / C0 × 100%.

[0193] Example 2

[0194] Except for the addition of ethyl dithioethyl, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention and storage capacity retention were tested. The results are shown in Table 1.

[0195] Example 3

[0196] Except for the additive being tetramethylthiuram monosulfide, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention and storage capacity retention were tested. The results are shown in Table 1.

[0197] Example 4

[0198] Except for the additive being ethyl 2-((ethoxycarbonthio)thio)ethyl acetate, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention and storage capacity retention were tested. The results are shown in Table 1.

[0199] Example 5

[0200] Except for the additive being sodium dimethyl dithiocarbamate hydrate, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0201] Example 6

[0202] Except for sodium ethyl xanthate as the additive, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0203] Example 7

[0204] Except for additives Except for (weight-average molecular weight 10,000), the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0205] Example 8

[0206] Except for additives Except for (weight-average molecular weight 10,000), the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0207] Example 9

[0208] Except that the particle size Dv50 of the additive is 12 μm, it was prepared according to the same steps as in Example 8, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0209] Example 10

[0210] Except for additives Except for (weight-average molecular weight 20,000), the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0211] Examples 11-14

[0212] Except for the mass ratios of the positive electrode active material, additives, binders, and conductive agents as shown below, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0213] Example 11, 98.4:0.1:1:0.5;

[0214] Example 12, 98.2:0.3:1:0.5;

[0215] Example 13, 97.5:1:1:0.5;

[0216] Example 14, 96.5:2:1:0.5.

[0217] Example 15

[0218] This embodiment provides a lithium-ion secondary battery, the preparation method of which is as follows:

[0219] (1) Positive electrode plate

[0220] LiNi will be used as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2 (particle size Dv50 of 8μm), polyvinylidene fluoride (PVDF) as a binder, and acetylene black as a conductive agent are dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 98.5:1:0.5. After thorough stirring and mixing, a positive electrode slurry is obtained. The positive electrode slurry is then uniformly coated onto a positive electrode current collector, followed by drying, cold pressing, and slitting to obtain the positive electrode sheet.

[0221] (2) Negative electrode plate

[0222] Artificial graphite (particle size Dv50 of 15 μm) as the negative electrode active material, tetraethyl thiuram disulfide (particle size Dv50 of 6 μm) as an additive, acetylene black as a conductive agent, styrene-butadiene rubber (SBR) as a binder, and sodium carboxymethyl cellulose (CMC) as a thickener were dissolved in deionized water at a mass ratio of 96.5:0.5:0.5:1.5:1 and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry was then evenly coated onto a copper foil for the negative electrode current collector, dried to obtain a negative electrode film, and then cold-pressed and slit to obtain a negative electrode sheet.

[0223] The other steps are the same as in Example 1, and the cycle capacity retention rate and storage capacity retention rate are tested. The results are shown in Table 1.

[0224] Example 16

[0225] Except that the particle size Dv50 of the additive is 15 μm, it was prepared according to the same steps as in Example 15, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0226] Example 17

[0227] Except that the particle size Dv50 of the additive is 20 μm, it was prepared according to the same steps as in Example 15, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0228] Example 18

[0229] Except for the positive electrode active material being LiNi 0.96 Co 0.02Mn 0.02 Except for O2 (particle size Dv50 of 8 μm), the same steps as in Example 1 were followed, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0230] Example 19

[0231] Except for the positive electrode active material being LiNi 0.9 Co 0.05 Mn 0.05 Except for O2 (particle size Dv50 of 8 μm), the same steps as in Example 1 were followed, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0232] Example 20

[0233] Except for the positive electrode active material being LiMn 0.6 Fe 0.4 Except for PO4 (particle size Dv50 of 1 μm), the same steps as in Example 1 were followed, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0234] Example 21

[0235] Except for the positive electrode active material being LiMn 0.4 Fe 0.6 Except for PO4 (particle size Dv50 of 1 μm), the same steps as in Example 1 were followed, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0236] Example 22

[0237] The preparation of the positive and negative electrode sheets was the same as in Example 1. The electrolyte was prepared as follows: In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), 1 mol / L LiPF6 was dissolved in an organic solvent (EC / DMC / EMC = 1 / 1 / 1), and 0.5% (by mass) of 2-mercaptothiazoline was added and stirred until homogeneous to obtain the electrolyte. Other steps were the same as in Example 1, and the cycle capacity retention and storage capacity retention were tested. The results are shown in Table 1.

[0238] Example 23

[0239] Except that the mass percentage of 2-mercaptothiazoline in the electrolyte was 1%, the preparation was carried out according to the same steps as in Example 22, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0240] Example 24

[0241] Except that the mass percentage of 2-mercaptothiazoline in the electrolyte is 3%, the preparation was carried out according to the same steps as in Example 22, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0242] Example 25

[0243] Except that the mass percentage of 2-mercaptothiazoline in the electrolyte is 5%, the preparation was carried out according to the same steps as in Example 22, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0244] Example 26

[0245] Except for the mass ratio of negative electrode active material, additive, conductive agent, binder and thickener being 96.8:0.2:0.5:1.5:1, the preparation was carried out according to the same steps as in Example 15, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0246] Example 27

[0247] Except for the mass ratio of negative electrode active material, additive, conductive agent, binder and thickener being 96:1:0.5:1.5:1, the preparation was carried out according to the same steps as in Example 15, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0248] Example 28

[0249] Except for the preparation method of the separator membrane as described below, the same steps as in Example 1 were followed, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0250] (1) Preparation of diaphragm slurry containing tetraethylthiuram disulfide: Tetraethylthiuram disulfide powder, inorganic oxide-alumina, and thickener-sodium carboxymethyl cellulose were dispersed in water as a dispersant at a mass ratio of 55:40:5 at 500 rpm / min.

[0251] (2) Preparation of the separating membrane: The obtained slurry is coated on both sides of a polyethylene film (7 μm thick) serving as the base film, and dried at 60°C by forced air to form a film layer on the surface of the base film. The additive accounts for 2 mg / 50*100 mm of the mass of the film layer. 2 .

[0252] Example 29

[0253] Except that the additive accounts for 3 mg / 50*100 mm of the film layer. 2In addition, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0254] Example 30

[0255] Except that the additive accounts for 5 mg / 50*100 mm of the mass of the film layer. 2 In addition, the preparation was carried out according to the same steps as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0256] Comparative Example 1

[0257] Except for the following differences, the same preparation and testing were performed according to Example 1, and the results are shown in Table 1.

[0258] The preparation method of the positive electrode sheet is as follows: LiNi is used as the positive electrode active material. 0.8 Co 0.1 Mn 0.1 O2 (particle size Dv50 of 8μm), polyvinylidene fluoride (PVDF) as a binder, and acetylene black as a conductive agent are dissolved in N-methylpyrrolidone (NMP) at a mass ratio of 98.5:1:0.5 and thoroughly mixed to obtain a positive electrode slurry. The positive electrode slurry is then uniformly coated onto a positive electrode current collector, followed by drying, cold pressing, and slitting to obtain a positive electrode sheet.

[0259] Comparative Example 2

[0260] Except for the positive electrode active material being LiMn 0.6 Fe 0.4 Except for PO4 (particle size Dv50 of 1 μm), the same preparation was carried out as in Example 1, and the cycle capacity retention rate and storage capacity retention rate were tested. The results are shown in Table 1.

[0261] Comparative Example 3

[0262] Except for the additive being 1,2-bis(diphenylphosphine)ethane, the same preparation was carried out as in Example 1, and the cycle capacity retention and storage capacity retention were tested. The results are shown in Table 1.

[0263] Table 1

[0264]

[0265]

[0266] according to Figure 7 Comparing the chelation immersion test results of Example 1 and Comparative Example 1, it can be seen that by using additives in the positive electrode, the dissolution of transition metal ions in the positive electrode is significantly reduced. Figure 8The changes in capacity retention of Example 1 and Comparative Example 1 as the number of cycles increases during the cycle capacity test are shown. It can be seen that the lithium-ion battery of Example 1 has a better capacity retention as the number of cycles increases. Figure 9 The diagram shows the change in capacity retention rate of Example 1 and Comparative Example 1 as the number of storage days increases during the storage capacity retention rate test. It can be seen that the lithium-ion battery of Example 1 exhibits a better capacity retention rate as the storage time increases.

[0267] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A battery cell, characterized in that, Includes positive electrode, separator, electrolyte and negative electrode; At least one of the positive electrode, the separator, the electrolyte, and the negative electrode contains an additive; the additive is selected from small organic molecules, organic polymers, or organic salts having S=C(R)-S functional groups; Wherein, R is hydrogen, substituted or unsubstituted straight-chain or branched alkyl, alkoxy, alkyl, aryl, heteroaryl, or cycloalkyl; or, R together with the sulfur atom in the carbon-sulfur single bond forms a substituted or unsubstituted saturated or unsaturated cycloalkyl.

2. The battery cell as described in claim 1, characterized in that, The additives include small organic molecules having the S=C(R)-S functional group; Wherein, R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl; Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

3. The battery cell as described in claim 1, characterized in that, The additives include organic polymers having S=C(R)-S functional groups; The organic polymer has polyacrylic acid as its main chain; and / or the weight-average molecular weight of the organic polymer is 5,000 to 100,000.

4. The battery cell as described in claim 1, characterized in that, The additives include organic salts having the S=C(R)-S functional group; The organic salt contains a metal cation M, wherein M is selected from lithium ions, sodium ions, potassium ions, zinc ions, and ammonium ions; and / or, The R is hydrogen, substituted or unsubstituted straight-chain or branched (C1-C6) alkyl, (C1-C6) alkoxyalkyl, aryl, heteroaryl, or (C3-C6) cycloalkyl; Alternatively, R, together with the sulfur atom in the carbon-sulfur single bond, forms a substituted or unsubstituted saturated or unsaturated (C3-C6) cycloalkyl group.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The substitution refers to the replacement of hydrogen or carbon in R by at least one of nitrogen, oxygen, or sulfur.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The additive is selected from at least one of the following groups: Where M is a metal cation.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The positive electrode includes a positive current collector and a positive electrode material layer disposed on at least one surface of the positive current collector; the positive electrode material layer contains a positive electrode active material and the additive, wherein the additive accounts for 0.3% to 1% of the mass percentage of the positive electrode material layer.

8. The battery cell as described in claim 7, characterized in that, The particle size Dv50 of the additive is less than or equal to the particle size Dv50 of the positive electrode active material.

9. The battery cell as described in claim 7 or 8, characterized in that, The positive electrode active material includes high-nickel positive electrode material and / or lithium manganese iron phosphate positive electrode material; The chemical formula of the high-nickel cathode material is Li. 1+a [Ni x Co y Mn z M1 b O2, where 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, and M1 is one or more of Mg, Ca, Sb, Ce, Ti, Zr, Sr, Al, Zn, Mo and B; The chemical formula of the lithium manganese iron phosphate cathode material is (LiMn) p Fe 1-p-q M2 q PO4), where 0.1≤p≤0.9, q≤0.05, and M2 is one or more of V, Ti, Mg, Ni, and Fe.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The negative electrode sheet includes a negative current collector and a negative electrode material layer disposed on at least one surface of the negative current collector, wherein the negative electrode material layer contains the additive; the additive accounts for 0.2% to 1.0% of the mass percentage of the negative electrode material layer.

11. The battery cell according to any one of claims 1 to 10, characterized in that, The separator includes a base film and a film layer disposed on at least one surface of the base film, the film layer containing the additive; the additive accounts for 2-5 mg / 50*100 mm of the film layer. 2 .

12. The battery cell according to any one of claims 1 to 11, characterized in that, The electrolyte includes the additive; the additive accounts for 0.5% to 5% of the electrolyte by mass.

13. A battery device, characterized in that, Includes the battery cell according to any one of claims 1 to 12.

14. An electrical appliance, characterized in that, Includes the battery cell according to any one of claims 1 to 12 or the battery device according to claim 13.

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