Lithium supplement dispersing agent and preparation method thereof, positive electrode slurry and secondary battery

Abstract

The invention relates to a lithium supplement dispersant and a preparation method thereof, a positive electrode slurry, a secondary battery, a lithium supplement component and a first solvent, the chemical formula of the lithium supplement component comprises R-(X-Li) n, R is a main chain group, X is a linking group, n is an integer greater than zero, the lithium supplement component is dissolved in the first solvent, and the lithium supplement component is used for dispersing active substances in the electrode slurry. The lithium-supplementing dispersing agent can prevent aggregation and viscosity rebound among electrode material particles, can also play roles in improving the solid content of slurry, reducing the viscosity of the slurry and enhancing the stability of the slurry, and can also additionally provide lithium ions and supplement lithium loss in the first charging process of a battery, so that the energy density of the battery is improved, and the cycle life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of secondary batteries, and in particular to a lithium supplementing dispersant and a preparation method thereof, a positive electrode slurry, and a secondary battery. Background Art

[0002] With the continuous consumption of non-renewable resources and a series of environmental problems caused by the use of fossil energy, humans urgently need to develop and utilize renewable clean energy. In order to achieve the sustainable utilization and output of clean energy, electrochemical energy storage technology has emerged. Among them, lithium-ion batteries are widely used due to their advantages such as high energy density, long cycle life, high voltage, small size and high safety.

[0003] Common cathode materials used in lithium-ion batteries include lithium iron phosphate and lithium iron manganese phosphate. These small particles of cathode materials often agglomerate during the slurry preparation process, resulting in excessive viscosity of the cathode slurry and poor viscosity stability, making slurry coating difficult and increasing process costs. Furthermore, the formation of the negative electrode SEI film and irreversible lithium insertion can lead to a loss of some active lithium, thereby reducing the overall battery capacity and cycle life. Therefore, how to achieve dispersion while also addressing lithium ion consumption becomes crucial. Summary of the Invention

[0004] The purpose of the present invention is to provide a lithium replenishing dispersant and a preparation method thereof, a positive electrode slurry, and a secondary battery, so as to solve the problem that the existing dispersants have poor dispersion effect and lack of lithium replenishing function.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a lithium-supplementing dispersant, comprising a lithium-supplementing component and a first solvent, wherein the chemical formula of the lithium-supplementing component comprises R-(X-Li)n, wherein R is a main chain group, X is a connecting group, and n is an integer greater than zero, and the lithium-supplementing component is dissolved in the first solvent, and the lithium-supplementing component is used to disperse the active material in the electrode slurry.

[0007] In some embodiments, the main chain group includes one or more of an alkyl group, an alkenyl group, and an aryl group, and the number of carbon atoms in the main chain group is 1 to 18.

[0008] In some embodiments, the linking group includes one or more of a carboxylic acid group, a phosphate group, and a sulfate group, and the lithium ions in the lithium supplement component are connected to the linking group via an ionic bond.

[0009] In some embodiments, the first solvent includes an organic alcohol solvent.

[0010] In some embodiments, the solubility of the lithium supplement component in the first solvent is 30 g to 80 g.

[0011] In some embodiments, the lithium-supplementing component accounts for 15% to 35% by weight of the lithium-supplementing dispersant.

[0012] In some embodiments, the lithium supplement dispersant further includes a dispersing component, which is dissolved or dispersed in the solvent. The dispersing component includes a flexible chain group and an anchoring group, and the anchoring group is connected to the flexible chain group.

[0013] In some embodiments, the flexible chain group includes one or more of polyolefin, polyester, polyether, and polyurethane.

[0014] In some embodiments, the anchoring group includes one or more of a carboxyl group, a hydroxyl group, a phenolic group, an amide group, an amino group, a benzene ring, and a polycyclic heterocycle.

[0015] In some embodiments, at least a portion of the lithium-containing groups in the lithium-supplementing component are grafted onto the dispersed component, and the lithium-containing groups include the linking group and the lithium ion.

[0016] In some embodiments, the sum of the mass proportions of the dispersed component and the lithium-supplementing component in the lithium-supplementing dispersant is greater than or equal to 30%.

[0017] In some embodiments, the mass ratio of the dispersed component to the lithium supplement component is (30-50): (50-70).

[0018] In some embodiments, the density of the lithium supplement dispersant is 1.0 g / cm 3 ~1.1g / cm 3 .

[0019] In some embodiments, the viscosity of the lithium-supplementing dispersant is less than or equal to 200 mPa·s.

[0020] In some embodiments, the water content of the lithium-supplementing dispersant is less than or equal to 1500 ppm.

[0021] In a second aspect, the present invention provides a method for preparing a lithium-supplementing dispersant, which is used to prepare the lithium-supplementing dispersant as described in the first aspect. The preparation method comprises: adding a lithium-supplementing component to a first solvent; and fully stirring to dissolve the lithium-supplementing component to obtain a lithium-supplementing dispersant.

[0022] In a third aspect, the present invention provides a positive electrode slurry, comprising a positive electrode active material, a second solvent, and the lithium supplementing dispersant as described in any one of the first aspects, wherein the second solvent is different from the first solvent.

[0023] In a fourth aspect, the present invention provides a secondary battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, wherein the positive electrode sheet is made using the positive electrode slurry described in the third aspect; or, the secondary battery comprises the lithium-supplementing component in the lithium-supplementing dispersant described in the first aspect.

[0024] The present invention provides a lithium-supplementing dispersant, which is mainly used in the positive electrode slurry of lithium-ion batteries. The lithium-supplementing component in the lithium-supplementing dispersant is dissolved in a solvent. The lithium-supplementing component can prevent aggregation and viscosity rebound between positive electrode material particles through the electrostatic repulsion between the double layers, so it can provide a dispersion effect in the solvent. At the same time, the lithium ions in the lithium-supplementing component can provide additional lithium ions during the first charging process of the battery, replenish lithium loss, and thus improve the energy density and cycle life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 1 is a flow chart of a method for preparing a lithium-supplementing dispersant in some embodiments.

[0027] Figure 2 is a schematic diagram of a secondary battery in one embodiment. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] It should be noted that the "ranges" disclosed herein are defined in the form of lower limits and upper limits. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive of the end values ​​and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. In addition, if the minimum range values ​​listed are 1 and 2, and if the maximum range values ​​listed are 3, 4, and 5, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5. In the present invention, unless otherwise specified, the numerical range "a to b" represents an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] All steps of the present invention may be performed sequentially or randomly, but are preferably performed sequentially. For example, a statement that a method includes steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a statement that a method may also include step (c) indicates that step (c) may be added to the method in any order, e.g., the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0032] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0033] The following is a description of the instrument used to test the lithium dispersant provided by the present invention:

[0034] 1) The molecular weight of the dispersed component can be measured by gas chromatography-mass spectrometry (GC-MS).

[0035] 2) The viscosity of the lithium supplement dispersant can be measured using a viscosity tester.

[0036]

Lithium Supplement Dispersant

[0037] In some embodiments, a lithium-supplementing dispersant is used in batteries and can be added to a slurry of electrode materials, specifically a slurry used to prepare lithium-ion batteries. The electrode material slurry includes a positive electrode active material, a positive electrode lithium-supplementing material, and a conductive agent. Of course, in other embodiments, the lithium-supplementing dispersant can also be added to the negative electrode material.

[0038] In some embodiments, a lithium-supplementing dispersant includes a lithium-supplementing component and a first solvent. The lithium-supplementing component has a chemical formula of R-(X-Li)n, where R is a backbone group, X is a linking group, and n is an integer greater than zero. The lithium-supplementing component is dissolved in the first solvent and is used to disperse the active material in the electrode slurry. Specifically, the lithium-supplementing dispersant is a liquid phase substance, and the lithium-supplementing component is dissolved in the first solvent. After the lithium-supplementing dispersant is added to the electrode slurry, the lithium-supplementing component can provide lithium replenishment and can also be used to disperse the active material in the electrode slurry, such as the positive electrode active material or the negative electrode active material.

[0039] In a specific embodiment, the lithium supplement component includes a lithium-containing organic compound, and the chemical formula of the lithium-containing organic compound is R-(X-Li) n , wherein R is a main chain group, which includes a carbon chain formed by connecting multiple carbon atoms, X is a linking group, lithium ions are connected to the linking group, and -X-Li together constitute a branch chain connected to the main chain group. n is the number of branch chains (-X-Li) in the lithium supplement component, and n is an integer greater than zero. Optionally, n can be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0040] In a specific embodiment, the first solvent is different from the solvent used to prepare the electrode slurry. To distinguish the first solvent from the solvent used to prepare the electrode slurry, the solvent used to prepare the electrode slurry is hereinafter referred to as the second solvent. The difference between the first solvent and the second solvent includes at least one of the following: different solubility of the lithium supplement component in the first solvent and the second solvent, different boiling points of the first solvent and the second solvent, different polarity of the first solvent and the second solvent, etc.

[0041] In a specific embodiment, the first solvent can be a low-boiling-point solvent such as ethanol, while the second solvent is typically N-methylpyrrolidone (NMP). In the prior art, a polar aprotic solvent is typically used as the second solvent to dissolve organic matter such as the binder and protect the electrode active material. However, the lithium-supplementing component provided by the present invention has poor solubility in the second solvent, or even insolubility, making it difficult to disperse the lithium-supplementing component in the second solvent.

[0042] The present invention provides a lithium-supplementing dispersant, which is mainly used in the positive electrode slurry of lithium-ion batteries. The lithium-supplementing component in the lithium-supplementing dispersant is dissolved in a solvent. The lithium-supplementing component can prevent aggregation and viscosity rebound between positive electrode material particles through the electrostatic repulsion between the double layers, so it can provide a dispersion effect in the solvent. At the same time, the lithium ions in the lithium-supplementing component can provide additional lithium ions during the first charging process of the battery, replenish lithium loss, and thus improve the energy density and cycle life of the battery.

[0043] In some embodiments, the main chain group includes one or more of an alkyl group, an alkenyl group, and an aryl group, and the number of carbon atoms in the main chain group is 1 to 18. Optionally, the number of carbon atoms in the main chain group can be 1, 2, 4, 6, 8, 10, 12, 14, 16, or 18; the main chain group includes dodecyl, octadecyl, dodecenyl, dodecylphenyl, and the like.

[0044] In some embodiments, the linking group comprises a carboxylic acid group (-COO - ), phosphate group (-PO4 2- ), sulfate (-OSO3 - ), the lithium ions in the lithium supplement component are connected to the linking group through an ionic bond. Specifically, the linking group and the lithium ions can together form a lithium carboxylate group (-COOLi), a lithium phosphate group (-PO4Li2), or a lithium sulfate group (-OSO3Li).

[0045] In specific embodiments, the role of the main chain group includes providing a connection site for the linking group, so it is necessary to control the type of main chain group and the number of carbon atoms in the main chain group. Among them, the hydrogen atoms in the alkyl, alkenyl, and aryl groups can form hydrogen bonds with the carbon layer on the surface of the positive electrode material, improving the stability of the lithium supplement component. Controlling the number of carbon atoms within the above range also allows for the formation of abundant connection sites on the main chain group, which can connect a large number of lithium ions and improve the lithium supplement capacity.

[0046] In a specific embodiment, the lithium supplement component includes lithium dodecyl sulfate (C 12 H 25 SO4Li), lithium stearate (C 18 H 35 O2Li), lithium dodecyl phosphate (C 12 H 25 PO4Li), lithium dodecylbenzenesulfonate (C 18 H 29 SO3Li), lithium perfluorobutanesulfonate (C4F9LiO3S) or more.

[0047] It can be understood that the above lithium-replenishing components are all ionic surfactants with lithium ions, which can not only be well dissolved in the first solvent, but also will not volatilize during the drying process, and will become solid and remain in the positive electrode. During the first charging process, after reaching the decomposition potential, the lithium-replenishing components will decompose and release lithium. After the lithium ions enter the electrolyte, they will replenish the lithium ions consumed by the formation of SEI film and irreversible lithium insertion at the negative electrode, thereby achieving the lithium replenishment effect.

[0048] In specific embodiments, the lithium-replenishing component ionizes in the electrode slurry to produce charged ions, which selectively adsorb onto the surface of solid particles to form a double layer (main chain groups and linking groups). The electrostatic repulsion between the double layers offsets the van der Waals attraction between the electrode active material particles, resulting in stable dispersion of the electrode active material particles. Furthermore, due to the hydrophobic nature of the main chain groups, they also provide an additional dispersing effect, allowing the lithium-replenishing component to achieve both lithium replenishment and dispersion.

[0049] In some embodiments, the first solvent includes an organic alcohol solvent, which refers to a liquid organic matter with a hydroxyl group (-OH) as a characteristic functional group. In a specific embodiment, the organic alcohol solvent includes one or more of ethanol, methanol, and propanol. Specifically, the above first solvents are all good solvents for the lithium-replenishing component, and the lithium-replenishing component can be fully dissolved in the above solvents to provide a dispersion effect. At the same time, the boiling point of the above first solvent is relatively low. During the preparation of the secondary battery, the first solvent evaporates, while the lithium-replenishing component as a solute does not evaporate, so that the lithium-replenishing component will become a solid and remain in the positive electrode sheet to provide a lithium-replenishing effect.

[0050] In some embodiments, the solubility of the lithium supplement component in the first solvent is 30g to 80g. It should be noted that the mass of the solute dissolved when the lithium supplement component reaches a saturated state in 100g of the first solvent is its solubility. Optionally, the solubility of the lithium supplement component in the first solvent can be 30g, 35g, 40g, 46g, 50g, 55g, 60g, 65g, 70g, 75g, 80g. Moreover, the solubility of the lithium supplement component in the first solvent is greater than the solubility of the lithium supplement component in the second solvent. It should be noted that the solubility of the lithium supplement component in the first solvent is the solubility at room temperature, and the room temperature range is 20℃ to 30℃.

[0051] Satisfying the solubility of the lithium supplement component in the first solvent within the above range allows the lithium supplement component to fully dissolve in the first solvent, thereby providing a dispersing effect. Furthermore, the lithium supplement component can be dissolved as much as possible in the first solvent, thereby improving the uniformity and stability of the lithium supplement dispersant. If the solubility of the lithium supplement component in the first solvent is too low, the lithium supplement component may not provide a high dispersion effect.

[0052] In some embodiments, the lithium-supplementing component accounts for 15% to 35% by weight of the lithium-supplementing dispersant. Optionally, the lithium-supplementing component accounts for 15%, 17%, 19%, 21%, 23%, 25%, 27%, 29%, 31%, 33%, or 35% by weight of the lithium-supplementing dispersant.

[0053] Meeting the above range of the mass ratio of the lithium-supplementing component in the lithium-supplementing dispersant ensures that the lithium-supplementing component can fully exert its effect. When the mass ratio of the lithium-supplementing component in the lithium-supplementing dispersant is too low, the lithium-supplementing and dispersion effects of the lithium-supplementing dispersant of the same mass will be reduced, and the viscosity of the electrode slurry will be reduced, which is not conducive to coating.

[0054] In some embodiments, the lithium supplement dispersant further comprises a dispersing component, the dispersing component being dissolved or dispersed in the solvent, the dispersing component comprising a flexible chain group and an anchoring group, the anchoring group being connected to the flexible chain group. Specifically, the dispersing component comprises a polymer, and the polymer can be dissolved in the first solvent or dispersed in the first solvent.

[0055] In a specific embodiment, the dispersing component includes a flexible chain group and an anchoring group, wherein the anchoring group connects to the flexible chain group. The flexible chain group is used to provide a steric hindrance effect in the electrode slurry to prevent interparticle aggregation and viscosity rebound; the anchoring group can form hydrogen bonds with the carbon film on the surface of the positive electrode material, thereby connecting to the surface of the positive electrode material, thereby dispersing the dispersed component between the particles of the positive electrode material to achieve a dispersion effect.

[0056] The present invention adds a dispersing component to the lithium-supplementing dispersant. The dispersing component can not only enhance the dispersing effect enhanced by the lithium-supplementing dispersant, but also promote the uniformity of the lithium-supplementing component in the first solvent, thereby improving the ionization constant and enabling the lithium-supplementing component to be evenly distributed in the electrode slurry, thereby improving the lithium-supplementing material and achieving sufficient lithium supplementation. In addition, the lithium-supplementing dispersant solution can also increase the solid content of the slurry, reduce the viscosity of the slurry, and enhance the stability of the slurry when added in a very small amount. The dispersing component can fully extend in the positive electrode slurry system, providing a huge steric hindrance effect, and preventing aggregation between particles and viscosity rebound.

[0057] In a specific embodiment, the lithium-supplementing component and the dispersing component act synergistically because the dispersing component is a high molecular polymer. In addition to its dispersing ability, the dispersing component also has metal chelating ability, such as polyacrylic acid and its copolymers, polyethyleneimine, etc., which can effectively chelate lithium ions, stabilize metal ions, reduce ion recombination, and promote the release of anions; thereby improving the ionization ability of the lithium-supplementing component in the second solvent, thereby improving the dispersing effect of the lithium-supplementing component.

[0058] In some embodiments, the flexible chain group includes one or more of polyolefins, polyesters, polyethers, and polyurethanes. Specifically, the flexible chain group refers to the portion remaining after the original polymer loses an atom or an atomic group (anchor group). The above polymer can maintain the viscosity and solid content of the electrode slurry, and the structure is stable and not easy to volatilize during the electrode drying process; the residual dosage is basically maintained in the final electrode product, and this residue helps prevent electrode cracking and maintain electrode stability.

[0059] In specific embodiments, the flexible chain groups can also improve the dispersibility between particles, ensuring uniform dispersion and preventing precipitation and agglomeration. Furthermore, the flexible chain groups can provide stability to the electrode slurry, with the stretching of the polymer chain segments creating steric hindrance and promoting uniform dispersion of the slurry.

[0060] In some embodiments, the anchoring group includes one or more of a carboxyl group, a hydroxyl group, a phenolic group, an amide group, an amino group, a benzene ring, and a polycyclic heterocyclic ring. Specifically, the anchoring group can interact with certain groups on the carbon material (e.g., the coating layer of the positive electrode material or the carbon negative electrode) to form anchoring sites, thereby preventing the electrode materials from connecting and agglomerating.

[0061] In specific embodiments, carboxyl groups can also neutralize residual alkaline reactions on the surface of the positive electrode material, thereby reducing the amount of residual alkaline on the surface of the positive electrode material and preventing alkaline substances from reacting with other materials such as adhesives to produce gelation. Hydroxyl groups, phenolic groups, and amino groups can also form hydrogen bonds with carbon materials, helping to reduce the viscosity of the electrode slurry. Furthermore, they can lose hydrogen atoms from their hydroxyl groups to form free radicals, thereby neutralizing other free radicals in the electrode slurry. This electron transfer process can effectively inhibit the oxidation reaction and enhance the air resistance of the electrode slurry.

[0062] In a specific embodiment, the dispersing component includes one or more of polyacrylic acid, ethylene-vinyl acetate copolymer, ethylene-acrylic acid or acrylate copolymer, polyethylene terephthalate, polybutylene terephthalate, polypropylene oxide, polyethylene oxide, polyether polyurethane, polyester polyurethane, polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl formal, and polyvinyl butyral.

[0063] In some embodiments, at least a portion of the lithium-containing groups in the lithium-supplementing component are grafted onto the dispersed component. The lithium-containing groups include a linking group and a lithium ion. Specifically, the lithium-containing groups are side chain groups connected to the main chain groups, formed by -X-Li in the above-described embodiments. It is understood that the groups on the dispersed component have metal chelating capabilities, thereby effectively chelating the lithium ions in the lithium-containing groups, allowing the lithium-containing groups to be grafted onto the dispersed component. This achieves the purpose of stabilizing metal ions, reducing ion recombination, and promoting anion dissociation.

[0064] In some embodiments, the molecular weight of the dispersed component is 5000 to 80000. Alternatively, the molecular weight of the dispersed component can be 5000, 10000, 15000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, or 80000.

[0065] In some embodiments, the sum of the mass proportions of the dispersed component and the lithium-supplementing component in the lithium-supplementing dispersant is greater than or equal to 30%. Optionally, the sum of the mass proportions of the dispersed component and the lithium-supplementing component in the lithium-supplementing dispersant can be 30%, 35%, 40%, 45%, 50%, 55%, or 60%. Of course, the mass proportion of the first solvent in the lithium-supplementing dispersant can be 70%, 65%, 60%, 55%, 50%, 45%, or 40%. Preferably, the sum of the mass proportions of the dispersed component and the lithium-supplementing component in the lithium-supplementing dispersant is 30% to 40%.

[0066] Meeting the above-mentioned mass ranges for the dispersing component and the lithium-supplementing component in the lithium-supplementing dispersant ensures the dispersing effect provided by the dispersing component and the lithium-supplementing component, and ensures that the lithium-supplementing component can provide as much lithium ions as possible. If the combined mass of the dispersing component and the lithium-supplementing component is too low, the lithium-supplementing dispersant will have too few active ingredients, failing to achieve the desired dispersing and lithium-supplementing effects. Furthermore, the viscosity of the dispersant will decrease, failing to increase the solids content of the slurry.

[0067] In some embodiments, the mass ratio of the dispersed component to the lithium supplement component is (30-50):(50-70). Alternatively, the mass ratio of the dispersed component to the lithium supplement component can be 30:70, 35:65, 40:60, 45:55, or 50:50. It should be noted that the mass ratio of the dispersed component to the lithium supplement component refers to the mass proportion of the dispersed component or the lithium supplement component in the active ingredient excluding the first solvent.

[0068] Meeting the above-mentioned mass ratio of the dispersed component to the lithium-supplementing component ensures the synergistic enhancement of the dispersed component on the lithium-supplementing component and ensures the lithium-supplementing capacity of the lithium-supplementing dispersant. When the mass ratio of the dispersed component is too low, the enhanced effect of the dispersed component on the lithium-supplementing dispersion is reduced, the ionization constant cannot be increased, and the lithium-supplementing effect provided by the lithium-supplementing material is reduced. When the mass ratio of the dispersed component is too high, the proportion of the lithium-supplementing component decreases, resulting in a decrease in the lithium-supplementing capacity contributed by the lithium-supplementing component.

[0069] In some embodiments, the density of the lithium dispersant is 1.0 g / cm 3 ~1.1g / cm 3 Optionally, the density of the lithium dispersant can be 1.0 g / cm 3 , 1.01g / cm3 , 1.02g / cm 3 , 1.03g / cm 3 , 1.04g / cm 3 , 1.05g / cm 3 , 1.06g / cm 3 , 1.07g / cm 3 、1.08g / cm 3 , 1.09g / cm 3 , 1.1g / cm 3 .

[0070] Maintaining the lithium-supplementing dispersant's density within the above range ensures both viscosity and fluidity. When the density of the lithium-supplementing dispersant is too low, it indicates too little active ingredient has been added, resulting in poor dispersion and lithium-supplementing properties. When the density of the lithium-supplementing dispersant is too high, it indicates too much active ingredient has been added, increasing viscosity and impairing fluidity.

[0071] In some embodiments, the viscosity of the lithium-supplementing dispersant is less than or equal to 200 mPa·s. Optionally, the viscosity of the lithium-supplementing dispersant can be 200 mPa·s, 190 mPa·s, 180 mPa·s, 170 mPa·s, 160 mPa·s, 150 mPa·s, 140 mPa·s, 130 mPa·s, 120 mPa·s, 110 mPa·s, or 100 mPa·s. Preferably, the viscosity of the lithium-supplementing dispersant is 50 mPa·s to 200 mPa·s.

[0072] The viscosity of the lithium-supplementing dispersant must be within the above range. Excessively high viscosity can reduce its diffusion efficiency in the slurry, leading to uneven wetting during the initial dispersion phase and even affecting dispersion uniformity due to localized excessive concentration. Furthermore, high viscosity can directly increase the overall viscosity of the slurry system, hindering subsequent processing (such as coating). In this case, rheological properties must be optimized by adjusting the first solvent ratio or shear force. Conversely, while lithium-supplementing dispersants with excessively low viscosity can easily penetrate particle aggregates, they may also reduce dispersion stability due to insufficient adsorption layer strength, especially during static storage or when subject to external disturbances, which can easily lead to particle reagglomeration.

[0073] In some embodiments, the water content of the lithium-supplementing dispersant is less than or equal to 1500 ppm. Optionally, the water content of the lithium-supplementing dispersant can be 1500 ppm, 1400 ppm, 1300 ppm, 1200 ppm, 1100 ppm, 1000 ppm, 900 ppm, 800 ppm, 700 ppm, 600 ppm, or 500 ppm.

[0074] Keeping the lithium-supplementing dispersant's water content within the above range prevents the dispersant from carrying excess water into the slurry, reducing the impact of water on the electrode material. If the water content of the lithium-supplementing dispersant is too high, the dispersant can carry excess water into the slurry, causing the electrode material to absorb water and affecting its performance.

[0075] Preparation method of lithium supplement dispersant

[0076] In some implementations, please refer to Figure 1 The preparation method of the lithium supplement dispersant specifically comprises the following steps:

[0077] Step S10: adding the lithium supplement component to the first solvent, stirring the solvent sufficiently to dissolve the lithium supplement component, and obtaining a lithium supplement dispersant containing the lithium supplement component.

[0078] In a specific embodiment, step S10 specifically includes: mixing the lithium supplement component and the first solvent, and subjecting the lithium supplement component to ultrasonic stirring to completely dissolve the lithium supplement component to obtain a primary solution, which can be used as a dispersant. The ultrasonic stirring time can be 12 hours to 24 hours.

[0079] In a specific embodiment, the first solvent and the second solvent are different, and the first solvent includes one or more of ethanol, methanol, and propanol.

[0080] In some embodiments, the lithium-supplementing dispersant further comprises a dispersing component, and the preparation method of the lithium-supplementing dispersant further comprises the following steps:

[0081] Step S20, adding the dispersed component to the lithium-supplementing dispersant containing the lithium-supplementing component, and stirring thoroughly to obtain the lithium-supplementing dispersant containing the lithium-supplementing component and the dispersed component.

[0082] In a specific embodiment, step S20 specifically includes: adding the dispersed component to the primary solution, and subjecting the solution to magnetic stirring until the dispersed component is completely dissolved to obtain a lithium-supplementing dispersant. The magnetic stirring time may be 6 to 12 hours.

[0083] In some embodiments, the preparation method of the lithium-supplementing dispersant further comprises:

[0084] Step S30: filtering the lithium-supplementing dispersant to obtain a filtered lithium-supplementing dispersant.

[0085] In a specific embodiment, some incompletely dissolved materials may be present in the lithium-supplementing dispersant, and impurities can be removed by filtering, wherein a 300-mesh screen can be used for filtration.

[0086]

Cathode slurry

[0087] In some embodiments, the positive electrode slurry includes a positive electrode active material, a second solvent, and a lithium-supplementing dispersant as provided in the above embodiments, and the second solvent is different from the first solvent.

[0088] In a specific embodiment, the positive electrode active material can reversibly intercalate and deintercalate active lithium ions, and the active lithium ions migrate between the positive electrode and the negative electrode of the battery to achieve battery charging and discharging. The positive electrode active material can be a phosphate positive electrode active material and a ternary positive electrode active material. Exemplarily, the positive electrode active material includes one or more of lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, and lithium vanadium oxyphosphate. In addition, additional lithium supplement materials can be added to the positive electrode active material. Exemplarily, the lithium supplement material can be lithium-rich lithium ferrite, lithium-rich lithium cobalt oxide, lithium-rich lithium nickel oxide, etc.

[0089] In a specific embodiment, the second solvent is the main solvent used to prepare the positive electrode slurry. The second solvent includes N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), etc., and can specifically be the positive electrode slurry provided by N-methylpyrrolidone (NMP).

[0090] In a specific embodiment, the positive electrode slurry is configured as follows: the positive electrode active material is added to the second solvent to configure the active slurry, and then the configured lithium replenishing dispersant is added to the second solvent to configure the dispersed slurry, and then the dispersed slurry and the active slurry are mixed to obtain the positive electrode slurry. Optionally, the dispersed component can be first added to the first solvent to prepare the lithium replenishing dispersant, or the dispersed component and the lithium replenishing dispersant (including only the lithium replenishing component) can be added to the second solvent to configure the dispersed slurry. It is understandable that the dispersed component can have better solubility in the second solvent.

[0091]

Positive electrode

[0092] In some embodiments, the positive electrode sheet includes an electrode material and a dispersant provided in the above embodiment, and the electrode material is a positive electrode material or a negative electrode material. Among them, the positive electrode material can reversibly deintercalate and deintercalate active lithium ions, and the active lithium ions migrate between the positive electrode and the negative electrode of the battery to realize battery charging and discharging. The positive electrode material can be a phosphate positive electrode material and a ternary positive electrode material. Exemplarily, the positive electrode material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadium oxyphosphate, fluorolithium vanadium phosphate, lithium titanate, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. And a lithium supplement material can be added to the positive electrode material. Exemplarily, the lithium supplement material can be lithium-rich lithium iron oxide, lithium-rich lithium cobalt oxide, lithium-rich lithium nickel oxide, etc.

[0093] Secondary batteries

[0094] In some implementations, please refer to Figure 2Secondary battery 1000 may be a commonly used component system in the prior art, for example, including a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. The electrolyte may be a solid electrolyte or a liquid electrolyte. When a solid electrolyte is selected, the separator may be used as an adaptor. The electrode sheet (which may be the positive electrode sheet or the negative electrode sheet described above) includes a current collector and an electrode material disposed on the current collector. The electrode material includes the dispersant provided above.

[0095] In some embodiments, the positive electrode plate is made using the positive electrode slurry provided in the above embodiments, or the secondary battery includes the lithium-supplementing component of the lithium-supplementing dispersant provided in the above embodiments. It is understood that the negative electrode plate may also include the lithium-supplementing component of the lithium-supplementing dispersant provided in the above embodiments.

[0096] The technical solution of the present invention is described in detail below through specific embodiments.

[0097] Example 1

[0098] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant includes a lithium-supplementing component R1 and a first solvent R3. The lithium-supplementing component R1 includes lithium dodecyl phosphate, and the first solvent R3 includes ethanol.

[0099] Among them, the solubility of the lithium supplement component in the first solvent is 30g; the mass proportion of the lithium supplement component in the lithium supplement dispersant is 20%; the viscosity of the lithium supplement dispersant is 100mPa.s; and the water content of the lithium supplement dispersant is 1000ppm.

[0100] The preparation method of the lithium supplement dispersant provided in this embodiment is as follows:

[0101] 1) adding the lithium supplement component to the first solvent, stirring the solution ultrasonically for 12 hours until the lithium supplement component is completely dissolved, thereby obtaining a lithium supplement dispersant.

[0102] 2) Filter the lithium-supplementing dispersant through a 300-mesh sieve to obtain the final finished lithium-supplementing dispersant.

[0103] Example 2

[0104] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that in Example 1 in that the lithium dodecyl phosphate in the lithium-supplementing component R1 is replaced by lithium dodecyl sulfate.

[0105] Example 3

[0106] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 1 in that the lithium-supplementing component accounts for 15% by weight of the lithium-supplementing dispersant.

[0107] Example 4

[0108] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that in Example 1 in that the lithium-supplementing component accounts for 28% by weight of the lithium-supplementing dispersant.

[0109] Example 5

[0110] This embodiment provides a lithium-supplementing dispersant, which includes a lithium-supplementing component R1, a dispersing component R2, and a first solvent R3. The lithium-supplementing component R1 includes lithium dodecyl phosphate, the dispersing component R2 includes polyacrylic acid, and the first solvent R3 includes ethanol.

[0111] Among them, the sum of the mass proportions of the dispersed component R2 and the lithium-supplementing component R1 in the lithium-supplementing dispersant is 35%; the mass ratio of the dispersed component R2 to the lithium-supplementing component R1 is 4:6; the viscosity of the lithium-supplementing dispersant is 140 mPa.s; the water content of the lithium-supplementing dispersant is 1000 ppm; and the molecular weight of the dispersed component R2 is 20,000.

[0112] The preparation method of the lithium supplement dispersant provided in this embodiment is as follows:

[0113] 1) adding the lithium supplement component to the first solvent, stirring the solution ultrasonically for 12 hours until the lithium supplement component is completely dissolved, thereby obtaining a primary solution.

[0114] 2) adding the dispersed components to the primary solution, and stirring the dispersed components magnetically for 6 hours until the dispersed components are completely dissolved to obtain a lithium supplementing dispersant.

[0115] 3) Filter the lithium-supplementing dispersant through a 300-mesh sieve to obtain the final finished lithium-supplementing dispersant.

[0116] Example 6

[0117] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 5 in that the polyacrylic acid in the dispersing component R2 is replaced by polyethyleneimine.

[0118] Example 7

[0119] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 5 in that the sum of the mass proportions of the dispersed component R2 and the lithium-supplementing component R1 in the lithium-supplementing dispersant is 45%.

[0120] Example 8

[0121] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 5 in that the sum of the mass proportions of the dispersed component R2 and the lithium-supplementing component R1 in the lithium-supplementing dispersant is 25%.

[0122] Example 9

[0123] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 5 in that the mass ratio of the dispersing component R2 to the lithium-supplementing component R1 is 6:4.

[0124] Example 10

[0125] This embodiment provides a lithium-supplementing dispersant. The difference between the lithium-supplementing dispersant provided in this embodiment and that in Example 5 is that the mass ratio of the dispersing component R2 to the lithium-supplementing component R1 is 2:8.

[0126] Example 11

[0127] This embodiment provides a lithium-supplementing dispersant. The difference between the lithium-supplementing dispersant provided in this embodiment and that in Example 5 is that the water content of the lithium-supplementing dispersant is 1500.

[0128] Example 12

[0129] This embodiment provides a lithium-supplementing dispersant. The lithium-supplementing dispersant provided in this embodiment differs from that provided in Example 5 in that the molecular weight of the dispersing component R2 is 80,000.

[0130] Comparative Example 1

[0131] This comparative example provides a second solvent, which is N-methylpyrrolidone (NMP).

[0132] Comparative Example 2

[0133] This comparative example provides a lithium supplement agent, which is lithium-rich lithium ferrite (conventional lithium supplement agent).

[0134] Comparative Example 3

[0135] This comparative example provides a lithium-supplementing dispersant. The dispersant includes a lithium-supplementing component and a second solvent. The lithium-supplementing component includes lithium dodecyl phosphate, and the second solvent includes N-methylpyrrolidone (NMP).

[0136] The parameters of the lithium-supplementing dispersants provided in Examples 1 to 12 and Comparative Examples 1 to 3 are shown in Table 1:

[0137] Table 1 Parameters of lithium supplement dispersants provided in Examples and Comparative Examples

[0138]

[0139] The lithium-supplementing dispersants provided in Examples 1-12 and the lithium-supplementing dispersants provided in Comparative Examples 1-3 were respectively prepared into positive electrode slurries, positive electrode sheets, and lithium-ion batteries according to the following methods:

[0140] Positive electrode slurry: lithium iron phosphate (Yuneng YN7), conductive agent SP (conductive carbon black), binder PVDF (polyvinylidene fluoride), and lithium supplement dispersant are added into a ball mill in a mass ratio of 96.5:1.3:2.2:3. According to the set slurry solid content, the corresponding first solvent NMP is added, and the mixture is mixed and ball-milled to obtain the positive electrode slurry.

[0141] Positive electrode sheet: The positive electrode slurry is coated on the surface of aluminum foil, rolled, and vacuum dried at 110°C overnight to obtain a positive electrode sheet;

[0142] Negative electrode sheet: Graphite, binder CMC (carboxymethyl cellulose), binder SBR (styrene-butadiene rubber) and conductive agent SP were mixed in a mass ratio of 95.8:1.2:2:1 and ball-milled to obtain a negative electrode slurry. The negative electrode slurry was coated on the surface of copper foil and vacuum-dried at 110°C overnight to obtain a negative electrode sheet.

[0143] Electrolyte: Ethylene carbonate and ethyl methyl carbonate were mixed in a volume ratio of 3:7, and LiPF6 was added to form an electrolyte. The concentration of LiPF6 was 1 mol / L.

[0144] Diaphragm: polypropylene microporous diaphragm;

[0145] Lithium-ion battery assembly: Assemble button-type lithium-ion full batteries in an inert atmosphere glove box in the order of graphite negative electrode sheet - diaphragm - electrolyte - positive electrode sheet.

[0146] Related performance tests

[0147] Viscosity Reduction Test: The solids content of the positive electrode slurries of the Examples and Comparative Examples was adjusted to 54%. The viscosity of the positive electrode slurries was measured using a viscometer at 30 rpm after 0.5 hours, 3 hours, and 24 hours. The viscosity change was used to determine the dispersant's viscosity reduction and stabilization performance. Solids content refers to the mass percentage of the remaining portion of the positive electrode slurry after drying under specified conditions.

[0148] Electrochemical performance test: The first cycle charge capacity and first cycle discharge capacity of the lithium ion batteries corresponding to the test examples and comparative examples were tested under the following test conditions: constant current and constant voltage charging, first cycle charge and discharge voltage 2.0-3.75V, current 0.1C, and cut-off current 0.01C.

[0149] The test results are shown in Table 2.

[0150] Table 2 Test results of the embodiments and comparative examples

[0151]

[0152] From the test results of Examples 1 to 12 and Comparative Example 1 in Table 2, it can be seen that when the lithium-supplementing dispersant provided by the present invention is added to the slurry, the viscosity of the positive electrode slurry with a solid content of 54% after discharge and after being placed for 3 hours and 24 hours is lower than that of the slurry without adding the dispersant, indicating that the slurry of the examples has good fluidity and coatability; in addition, the secondary battery containing the dispersant prepared by the present invention has a high charge and discharge specific capacity, indicating that the lithium-supplementing dispersant can provide a lithium-supplementing effect.

[0153] From the test results of Examples 1 to 12 and Comparative Example 2 in Table 2, it can be seen that, compared with conventional lithium supplements that only have the function of replenishing lithium, the lithium supplement provided by the present invention can achieve the functions of dispersion and lithium replenishment without requiring dispersion, and can also avoid the slurry gel problem caused by conventional lithium supplements, thereby improving the processing performance of the slurry.

[0154] From the test results of Examples 1 to 12 and Comparative Example 3 in Table 2, it can be seen that the compatibility of the lithium replenishing component R1 and the first solvent R3 has an impact on the dispersion and lithium replenishing effect. Since lithium dodecyl phosphate is insoluble in NMP, the lithium replenishing component R1 cannot exert its effect.

[0155] The test results of Examples 1 and 2 in Table 2 show that the lithium-supplementing dispersant provided by the present invention can utilize different lithium-supplementing components R1 and achieve the same dispersion and lithium-supplementing effects. This indicates that the lithium-supplementing dispersant provided by the present invention has strong applicability and is suitable for industrial production.

[0156] From the test results of Example 1, Example 3 and Example 4 in Table 2, it can be seen that the content of the lithium supplement component R1 has an impact on the performance of the lithium supplement dispersant. When the content of the lithium supplement component R1 is low, its viscosity reduction and viscosity stabilization effect becomes worse, and the lithium supplement capacity becomes lower; when the content of the lithium supplement component R1 is high, its viscosity reduction and viscosity stabilization effect becomes better, and the lithium supplement capacity becomes higher.

[0157] The test results of Examples 1 and 5 in Table 2 demonstrate a synergistic effect between the lithium supplement component R1 and the dispersing component R2. Because the dispersing component R2 possesses metal chelating capacity in addition to its dispersing capacity, it effectively chelates lithium ions, stabilizes metal ions, reduces ion recombination, and promotes anion dissociation. This enhances the ionization capacity of the lithium supplement component R1 in NMP, thereby improving the dispersing effect of the lithium supplement component R1.

[0158] The test results of Examples 5 and 6 in Table 2 show that the lithium-supplementing dispersant provided by the present invention can utilize different dispersing components R2 and achieve the same dispersion and lithium-supplementing effects. This indicates that the lithium-supplementing dispersant provided by the present invention has strong applicability and is suitable for industrial production.

[0159] From the test results of Example 5, Example 7 and Example 8 in Table 2, it can be seen that the total content of the lithium supplement component R1 and the dispersing component R2 has an impact on the performance of the lithium supplement dispersant. When the content of the lithium supplement component R1 and the dispersing component R2 is low, the viscosity reduction and stabilization effect is worse, and the dispersion effect and lithium supplement effect are worse; when the content of the lithium supplement component R1 and the dispersing component R2 is high, the excess components cannot be dissolved in the first solvent R3. Therefore, Example 5 and Example 7 have similar effects.

[0160] The test results for Examples 5, 9, and 10 in Table 2 show that the ratio of lithium-supplementing component R1 to dispersed component R2 must be controlled within an appropriate range. When the dispersed component R2 accounts for an excessive amount, its viscosity reduction and stabilization effects improve, but the lithium-supplementing effect deteriorates. When the lithium-supplementing component R1 accounts for an excessive amount, the lithium-supplementing effect improves, but the viscosity reduction and stabilization effects deteriorate. Therefore, the ratio of lithium-supplementing component R1 to dispersed component R2 must be controlled within an appropriate range to fully utilize their synergistic effects.

[0161] From the test results of Example 5, Example 11 and Example 12 in Table 2, it can be seen that when the molecular weight of the dispersed component R2 increases, the steric hindrance effect it brings is enhanced, and the slurry viscosity stabilization effect becomes better. However, due to the increased entanglement between the long chains, the viscosity reduction effect becomes worse; and as the molecular weight increases, its conductivity becomes worse, which leads to a decrease in electrical performance.

[0162] In the description of the embodiments of the present invention, it should be noted that the orientations or positional relationships of terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inside" and "outside" are based on the orientations or positional relationships of the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0163] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A lithium supplement dispersant, characterized in that: The invention comprises a lithium supplement component and a first solvent, wherein the chemical formula of the lithium supplement component comprises R-(X-Li) n , wherein R is a main chain group, X is a connecting group, n is an integer greater than zero, and the lithium supplement component is dissolved in the first solvent, and the lithium supplement component is used to disperse the active material in the electrode slurry.

2. The lithium supplement dispersant according to claim 1, characterized in that The main chain group includes one or more of an alkyl group, an alkenyl group, and an aryl group, and the number of carbon atoms in the main chain group is 1 to 18; and / or the connecting group includes one or more of a carboxylic acid group, a phosphate group, and a sulfate group, and the lithium ions in the lithium supplement component are connected to the connecting group through an ionic bond.

3. The lithium supplement dispersant according to claim 1 or 2, characterized in that The first solvent comprises an organic alcohol solvent; and / or The solubility of the lithium supplement component in the first solvent is 30g to 80g; and / or The lithium-supplementing component accounts for 15% to 35% by mass of the lithium-supplementing dispersant.

4. The lithium supplement dispersant according to claim 1, characterized in that The lithium supplement dispersant further includes a dispersing component, which is dissolved or dispersed in the solvent. The dispersing component includes a flexible chain group and an anchoring group, and the anchoring group is connected to the flexible chain group.

5. The lithium supplement dispersant according to claim 4, characterized in that The flexible chain group includes one or more of polyolefins, polyesters, polyethers, and polyurethanes; and / or the anchoring group includes one or more of carboxyl groups, hydroxyl groups, phenolic groups, amide groups, amino groups, benzene rings, and polycyclic heterocycles.

6. The lithium supplement dispersant according to claim 4, characterized in that At least a portion of the lithium-containing groups in the lithium-supplementing component are grafted onto the dispersed component, and the lithium-containing groups include the connecting group and lithium ions.

7. The lithium supplement dispersant according to any one of claims 4 to 6, characterized in that The molecular weight of the dispersed component is 5,000 to 80,000; and / or The sum of the mass proportions of the dispersed component and the lithium-supplementing component in the lithium-supplementing dispersant is greater than or equal to 30%; and / or The mass ratio of the dispersed component to the lithium supplement component is (30-50): (50-70); and / or The viscosity of the lithium-supplementing dispersant is less than or equal to 200 mPa·s; and / or The water content of the lithium-supplementing dispersant is less than or equal to 1500 ppm.

8. A method for preparing a lithium supplement dispersant, characterized in that: The preparation method is used to prepare the lithium supplement dispersant according to any one of claims 1 to 7, and the preparation method comprises: adding a lithium supplement component to the first solvent; The lithium-supplementing dispersant is obtained after the lithium-supplementing component is dissolved by sufficient stirring.

9. A positive electrode slurry, characterized in that: The positive electrode slurry includes a positive electrode active material, a second solvent, and the lithium supplementing dispersant according to any one of claims 1 to 7, wherein the second solvent is different from the first solvent.

10. A secondary battery, characterized in that: The secondary battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, wherein the positive electrode sheet is made from the positive electrode slurry described in claim 9; or, the secondary battery comprises the lithium-supplementing component in the lithium-supplementing dispersant according to any one of claims 1 to 7.

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