Lithium supplement additive, positive electrode sheet, battery, and electric device

Abstract

A lithium supplement additive, a positive electrode sheet, a battery, and an electric device. The lithium supplement additive comprises: a first lithium supplement agent, wherein the first lithium supplement agent comprises a first core, and the first core satisfies a chemical formula LiaMbOc, wherein a is 1.5-6, b is 0-2, c is 1-6, and the element M comprises at least one of a magnesium element, a calcium element, a vanadium element, a chromium element, a manganese element, an iron element, a cobalt element, a nickel element, a copper element, a zinc element, a niobium element, a molybdenum element, a ruthenium element, a tin element, a silicon element, a carbon element and a boron element; and a second lithium supplement agent, wherein the second lithium supplement agent comprises a second core, and the second core satisfies a chemical formula LidCeOf, wherein d is 1.5-6, e is 3-5, and f is 1.5-6. The mass fraction of the first lithium supplement agent in the lithium supplement additive is m1, the mass fraction of the second lithium supplement agent in the lithium supplement additive is m2, and m1:m2 is smaller than or equal to (10:1).

Description

Lithium supplement additives, positive electrode sheets, batteries, and electrical devices Technical Field

[0001] The present disclosure relates to the field of battery technology, specifically, to lithium supplement additives, positive electrode sheets, batteries, and electrical devices. Background Art

[0002] Lithium-ion batteries are widely used in portable electronic devices, electric vehicles, and energy storage systems due to their high energy density, long cycle life, and excellent rate capability. Further improving the energy density and cycle life of lithium-ion batteries has become a research hotspot in the battery field. Lithium loss is a direct cause of battery degradation. For example, during the initial charge and discharge cycle of a battery, the electrolyte forms a solid electrolyte interface film (SEI) on the surface of the negative electrode. This SEI formation consumes a large amount of active lithium ions, resulting in a low coulombic efficiency during the first cycle of the battery. During the charge and discharge cycle, the cracking and shattering of the positive electrode active material particles and the thickening and repair of the SEI film all consume active lithium ions, leading to a significant decrease in battery cycle performance. The addition of lithium-supplementing additives can improve the first-cycle efficiency, energy density, and cycle life of lithium batteries. However, current lithium-supplementing additives are in the early stages of development and still have many shortcomings in production and application.

[0003] It should be noted that the above statements are only used to provide background technical information related to this application and do not necessarily constitute prior art.

[0004] Application Contents

[0005] In the first aspect of the present application, the present application proposes a lithium supplement additive, comprising: a first lithium supplement agent, the first lithium supplement agent comprising a first core, the first core satisfying the chemical formula Li a M b O c , wherein a is 1.5-6, b is 0-2, c is 1-6, and the M element includes at least one of magnesium, calcium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, tin, silicon, carbon, and boron; a second lithium supplement, wherein the second lithium supplement includes a second core, and the second core satisfies the chemical formula Li d C e O f , d is 1.5-6, e is 3-5, and f is 1.5-6. The mass fraction of the first lithium supplement in the lithium supplement additive is m1, the mass fraction of the second lithium supplement in the lithium supplement additive is m2, and m1:m2 is less than or equal to (10:1). This can reduce the agglomeration of lithium supplement additive particles, which can lead to processing defects such as slurry gelation, and improve the lithium supplement effect of the lithium supplement additive.

[0006] In some embodiments, the mass fraction of carbon in the first lithium supplement is k1, the mass fraction of lithium in the first lithium supplement is q1, and k1 / q1 is 0 to 2. This can further improve the lithium supplement effect of the lithium supplement additive.

[0007] In some embodiments, the mass fraction of carbon in the second lithium supplement is k2, the mass fraction of lithium in the second lithium supplement is q2, and k2 / q2 is greater than or equal to 2.5. This can reduce particle agglomeration of the lithium supplement additive, which can lead to processing problems such as slurry gelation, while also improving the lithium supplementation effect of the lithium supplement additive. This can further enhance the lithium supplementation effect of the lithium supplement additive.

[0008] In some embodiments, the first lithium supplement includes a first core and a first coating layer, wherein the first coating layer covers at least a portion of the surface of the first core, and the first coating layer includes at least one of a metal fluoride, a metal oxide, a metal phosphate, a ternary lithium salt, a carbon material, poly (3,4-ethylenedioxythiophene), and polypyrrole. This can reduce the alkalinity of the first lithium supplement.

[0009] In some embodiments, the second lithium supplement agent includes a porous carbon support and a second core, wherein the second core is located within the pore structure of the porous carbon support, thereby improving the conductivity of the second lithium supplement agent.

[0010] In some embodiments, the particle size of the first lithium supplement is larger than that of the second lithium supplement, at least a portion of the surface of the first core is coated with a second coating, and the second coating comprises the second lithium supplement. This simplifies the manufacturing process of the first lithium supplement and reduces the alkalinity of the first lithium supplement.

[0011] In some embodiments, k1 is 0%-30%, and q1 is 7%-70%. Thus, the first lithium replenisher has a higher lithium replenishing gram capacity.

[0012] In some embodiments, k2 is 15%-70%, and q2 is 8%-20%. Thus, the second lithium supplement has both high conductivity and low alkalinity.

[0013] In some embodiments, the first core satisfies at least one of the following conditions: when a is 2 and c is 2, M includes at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, and Cu; when a is 2 and c is 3, M includes at least one of Si, Ni, Co, Fe, Mn, Sn, and Cr; when a is 2 and c is 4, M includes at least one of C, Fe, Mn, Cr, and Nb; when a is 3 and c is 4, M includes at least one of Co, Fe, Mn, Cr, V, Mo, and Nb; when a is 5 and c is 4, M includes at least one of Ni, Co, Fe, Mn, Cr, and Mo; and when a is 6 and c is 4, M includes at least one of Ni, Co, Mn, Fe, Cu, and Ru. Thus, the lithium replenishment capacity of the first lithium replenisher can be further increased.

[0014] In some embodiments, the second core includes at least one of Li2C3O5, Li2C4O4, and Li2C4O6. This can further reduce the alkalinity of the second lithium supplement.

[0015] In some embodiments, the Dv50 particle size of the first lithium supplement is d1, the Dv50 particle size of the second lithium supplement is d2, and d1 / d2 is greater than or equal to 2. Thus, the addition of the lithium supplement additive can increase the porosity of the positive electrode sheet and improve the wetting effect of the electrolyte on the positive electrode sheet.

[0016] In a second aspect, the present application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material and a lithium replenishing additive, wherein the lithium replenishing additive comprises the aforementioned lithium replenishing additive. Thus, the positive electrode plate possesses all the features and advantages of the aforementioned lithium replenishing additive, which will not be further elaborated here.

[0017] In some embodiments, the mass fraction of the lithium supplement additive in the positive electrode active material layer is 0.1%-10%, thereby improving the energy density and electrolyte wettability of the positive electrode sheet.

[0018] In some embodiments, the positive electrode active material layer further includes a binder, wherein the binder includes at least one of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, hydrogenated nitrile rubber, polytetrafluoroethylene, and polyacrylic acid. This can improve the bonding effect between the positive electrode active material layer and the positive electrode current collector.

[0019] In a third aspect of the present application, a battery is provided, comprising the aforementioned positive electrode sheet. Thus, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0020] In a fourth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0022] FIG1 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0023] FIG2 is an exploded view of a battery cell according to an embodiment of the present application shown in FIG1 ;

[0024] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application;

[0025] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0026] FIG5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG4 ;

[0027] FIG6 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0028] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 battery cell; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0029] Below, the lithium supplement additive and its preparation method, positive electrode plate, battery, and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0030] " scope " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all 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] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0032] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; unless otherwise specified, the numerical values ​​of the various parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0034] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly specifying the quantity of the technical features indicated. "First feature" and "second feature" may include one or more of the features.

[0035] In the description of this application, “plurality” means two or more.

[0036] In the description of this application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for example, and may be any technical feature connected by "and / or" in this application.

[0037] On the one hand, lithium replenishers can make up for the loss of active lithium ions caused by the formation of SEI during the initial charge and discharge process, so that the battery has enough reversible active lithium ions in the subsequent cycle process, thereby improving the battery's energy density; on the other hand, lithium replenishers can also be used to make up for the lithium consumption that occurs during the cycle process, thereby improving the battery's cycle performance. According to the position of the lithium replenisher in the battery, it can be divided into positive electrode lithium replenishers and negative electrode lithium replenishers. The positive electrode lithium replenisher can form a positive electrode slurry together with the positive electrode active material, binder, etc., and then be coated on the surface of the positive electrode current collector to form a positive electrode active material layer. The lithium replenisher releases lithium ions during the first charge of the battery to make up for the loss of active lithium ions caused by phenomena such as the formation of SEI. In order to improve the lithium replenishment effect, lithium-rich materials with a high lithium ion content are usually used as lithium replenisher additives.

[0038] Lithium-rich materials have strong alkalinity. The excessive alkalinity of lithium-rich materials causes them to react with acidic binders when preparing positive electrode slurry. For example, taking the binder polyvinylidene fluoride (PVDF) as an example, when PVDF is mixed with a lithium supplement, the strongly alkaline lithium supplement will attack the carbon-carbon bonds of PVDF, causing PVDF to decompose and release hydrogen fluoride molecules, resulting in poor chemical gelation of the positive electrode slurry, which in turn reduces the bonding strength between the positive electrode active material layer and the positive electrode current collector, and makes it easy for the positive electrode active material layer to peel off from the surface of the positive electrode current collector.

[0039] In the present application, by mixing a first alkaline lithium supplement agent with a second acidic lithium supplement agent, the composite lithium supplement additive is weakly alkaline. When the mixed lithium supplement additive is mixed with an acidic binder, the lithium supplement additive has a weak alkalinity and therefore causes less damage to the acidic binder, thereby reducing the occurrence of poor chemical gelation of the positive electrode slurry and effectively improving the processing performance of the positive electrode slurry. At the same time, the lithium supplement additive can also better exert its lithium supplement performance and improve the battery cycle performance.

[0040] In the first aspect of the present application, the present application proposes a lithium supplement additive, comprising: a first lithium supplement agent, the first lithium supplement agent comprising a first core, the first core satisfying the chemical formula Li a M b O c, wherein a is 1.5-6, b is 0-2, c is 1-6, and the M element includes at least one of magnesium (Mg), calcium (Ca), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), niobium (Nb), molybdenum (Mo), ruthenium (Ru), tin (Sn), silicon (Si), carbon (C), and boron (B), and the average valence state of the M element in the first kernel is less than or equal to the highest oxidation valence state of the M element.

[0041] As an example, a can be 1.5, 2, 3, 4, 5, or 6.

[0042] As an example, b can be 0, 1, or 2.

[0043] When b is 0, the first core is a binary lithium-containing compound. As an example, the binary lithium-containing compound may include Li2O and Li2O2.

[0044] As an example, c can be 1, 2, 3, 4, 5 or 6.

[0045] The addition of the first lithium supplement agent can effectively increase the lithium supplement gram capacity of the lithium supplement additive.

[0046] As an example, the first core may include Li2C2O4, Li2CO3, Li2SiO3, or Li3BO3.

[0047] Unless otherwise specified, in the above chemical formula, when M is two or more elements, the above-mentioned numerical range for b is not only limited to the stoichiometric number of each element serving as M, but also to the sum of the stoichiometric numbers of each element serving as M. For example, when M includes two or more elements M1, M2, M3, ..., Mn, the stoichiometric numbers b1, b2, b3, ..., bn of M1, M2, M3, ..., Mn must each fall within the numerical range for b defined in this application, and the sum of b1, b2, b3, ..., bn must also fall within this numerical range.

[0048] In some embodiments, the first core satisfies at least one of the following conditions: when a is 2 and c is 2, M includes at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, and Cu; when a is 2 and c is 3, M includes at least one of Si, Ni, Co, Fe, Mn, Sn, and Cr; when a is 2 and c is 4, M includes at least one of C (carbon element), Fe, Mn, Cr, and Nb; when a is 3 and c is 4, M includes at least one of Co, Fe, Mn, Cr, V, Mo, and Nb; when a is 5 and c is 4, M includes at least one of Ni, Co, Fe, Mn, Cr, and Mo; when a is 6 and c is 4, M includes at least one of Ni, Co, Mn, Fe, Cu, and Ru. Thus, the lithium replenishment capacity of the first lithium replenisher can be further increased. When the first core satisfies at least one of the above chemical formulas, the first core contains two or more lithium ions, has a higher irreversible capacity, and has better stability in air. By combining different elements, the decomposition potential of the core can also be regulated, helping it to better release active lithium ions.

[0049] It is understood that when the M element includes a metal element, Li a M b O c The M element in the mixture should not be completely in its highest oxidation state, that is, the average valence state is less than the highest oxidation state, so that the lithium supplement can release lithium ions through the valence change of the M element.

[0050] It is understood that the above description of the first core is only an example, and those skilled in the art can adjust the material composition of the first core according to actual conditions. For example, the first core can be obtained by mixing LiMn2O4 and Li2MnO3 in any proportion, or the first core can also be Li4Ti5O 12 And other lithium-rich materials with special structures.

[0051] In some embodiments, the second core satisfies the chemical formula Li d C e O f (C is carbon element), d is 1.5-6, e is 3-5, and f is 1.5-6.

[0052] As an example, d may be 1.5, 2, 3, 4, 5, or 6.

[0053] As an example, e can be 3, 4 or 5.

[0054] As an example, f may be 1.5, 2, 3, 4, 5, or 6.

[0055] By blending the second lithium supplement agent with the first lithium supplement agent, the alkalinity of the first lithium supplement agent can be effectively reduced.

[0056] In some embodiments, the first lithium supplement agent and the second lithium supplement agent can be added to the positive electrode slurry separately and then blended in the positive electrode slurry, or the first lithium supplement agent and the second lithium supplement agent can be pre-blended and then added to the positive electrode slurry.

[0057] In some embodiments, the second core may include at least one of Li2C3O5, Li2C4O4, and Li2C4O6.

[0058] Lithium supplements are Li x C y O z For example, based on the acid-base proton theory, lithium belongs to alkali metals, lithium oxalate is a strong base weak acid salt, and is alkaline; when Li x C y O z When the proportion of carbon in the lithium supplement increases, the acidity of the lithium supplement increases. x C y O z When the proportion of lithium in the lithium supplement increases, the alkalinity of the lithium supplement agent increases. It can be seen that for the lithium supplement agent, as the lithium mass fraction increases, the lithium supplement capacity of the lithium supplement agent increases accordingly, and the alkalinity of the lithium supplement agent also increases accordingly; correspondingly, as the carbon mass fraction increases, the alkalinity of the lithium supplement agent decreases accordingly, and the lithium supplement capacity of the lithium supplement agent decreases accordingly. Therefore, by adding a first lithium supplement agent with a higher lithium mass fraction, the lithium supplement capacity of the lithium supplement additive can be increased, and the lithium supplement effect can be improved; by adding a second lithium supplement agent with a higher carbon mass fraction, the acidity and alkalinity of the lithium supplement additive can be improved, so that the lithium supplement additive presents a weak alkalinity, reducing the defects such as gelation of the positive electrode slurry caused by the excessive alkalinity of the lithium supplement additive. By using the first lithium supplement agent and the second lithium supplement agent together as lithium supplement additives, it is possible to improve the lithium supplement effect of the lithium supplement additive and improve the processing performance of the positive electrode slurry containing the lithium supplement additive.

[0059] In some embodiments, the mass fraction of the carbon element in the first lithium supplement is k1, the mass fraction of the lithium element in the first lithium supplement is q1, and k1 / q1 is 0-2; the second lithium supplement, the mass fraction of the carbon element in the second lithium supplement is k2, the mass fraction of the lithium element in the second lithium supplement is q2, and k2 / q2 is greater than or equal to 2.5.

[0060] As an example, k1 / q1 can be 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.5, 1.8, 1.9 or 2.

[0061] As an example, k2 / q2 can be 2.5 to 12. Specifically, k2 / q2 can be 2.5, 2.8, 3.0, 3.2, 3.5, 3.8, 4.0, 4.2, 4.5, 4.8, 5.0, 5.2, 5.5, 5.8, 6.0, 6.2, 6.5, 6.8, 7.0, 7.2, 7.5, 7.8, 8.0, 8.2, 8.5, 8.8, 9.0, 9.2, 9.5, 9.8, 10.0, 10.2, 10.5, 10.8, 11.0, 11.2, 11.5, 11.8 or 12.0.

[0062] In some embodiments, the first lithium supplement includes a first core and a first coating layer, the first coating layer covers at least a portion of the surface of the first core, and the first coating layer includes at least one of metal fluoride, metal oxide, metal phosphate, ternary lithium salt, carbon material, poly (3,4-ethylenedioxythiophene), and polypyrrole.

[0063] As an example, the metal fluoride may include AlF3; the metal oxide may include at least one of V2O5, Al2O3, ZrO2, TiO2, ZnO, Co3O4, SiO2; the metal phosphate may include at least one of AlPO4, FePO4, Co3(PO4)2, Ni3(PO4)2; the ternary lithium salt may include at least one of Li3PO4, Li2MnO3, LiAlO2, Li2TiO3, Li2ZrO3; the carbon material may include at least one of graphene and carbon nanotubes.

[0064] In some embodiments, the first coating layer may include a first sub-coating layer and a second sub-coating layer stacked together, wherein the first sub-coating layer is located on a side close to the first core, the first sub-coating layer may include at least one of Al2O3 and Li3PO4, and the second sub-coating layer may include at least one of polyethylene glycol-modified poly (3,4-ethylenedioxythiophene), polypyrrole, and carbon materials.

[0065] As an example, when the first sub-coating layer is Al2O3, the second sub-coating layer is polyethylene glycol-modified poly (3,4-ethylenedioxythiophene); when the first sub-coating layer is Li3PO4, the second sub-coating layer is polypyrrole.

[0066] When the first coating layer includes a carbon material, the conductive property of the first lithium supplement agent can be effectively improved.

[0067] Taking lithium oxalate as an example, although the carbon atoms in lithium oxalate are sp 2Hybridization, but because the carbon atoms in lithium oxalate need to be connected to one carbon atom and two oxygen atoms, the electron cloud density near the carbon atoms is low, the electrical conductivity is poor, and the decomposition potential is high. Therefore, it is necessary to form a coating layer on the surface of the first core. The setting of the first coating layer can improve the ion conductivity and electronic conductivity of the first core, thereby improving the lithium ion release capacity of the first lithium supplement. At the same time, the alkaline substances such as lithium oxide remaining on the surface of the first core can be removed, and the problems such as water absorption of the first lithium supplement caused by the excessive alkalinity of the first lithium supplement and gelation of the positive electrode slurry during processing can be improved.

[0068] In some embodiments, the second lithium supplementing agent may include a porous carbon support and a second core, wherein the second core is located within the pore structure of the porous carbon support.

[0069] As an example, the second core can be recrystallized in the pore structure of the porous carbon support by a liquid phase synthesis method, thereby obtaining a second lithium supplement with the second core located in the pore structure of the porous carbon support.

[0070] By arranging the second core in the pore structure of the porous carbon support with good conductivity, the conductivity of the second lithium supplement agent can be effectively improved, which is conducive to the release of the lithium supplement capacity.

[0071] In some embodiments, the porous carbon support comprises at least one of activated carbon, carbon nanotubes, carbon nitride, and carbon nitride nanotubes.

[0072] In some embodiments, the second lithium supplement agent can be coated on the surface of the first lithium supplement agent, i.e., the aforementioned lithium supplement additive is obtained by coating. The particle size of the first lithium supplement agent is larger than the particle size of the second lithium supplement agent, and at least a portion of the surface of the first core is provided with the second coating layer, which includes the second lithium supplement agent. i.e., the second lithium supplement agent covers at least a portion of the surface of the first core to form the second coating layer.

[0073] When the second lithium supplement agent is disposed on the surface of the first lithium supplement agent in the form of a coating layer, the first lithium supplement agent can share the porous carbon support of the second lithium supplement agent with the second lithium supplement agent to improve the conductivity of the first lithium supplement agent, thereby eliminating the need to form a carbon material coating layer on the surface of the first core.

[0074] In some embodiments, k1 is 0%-30%, and q1 is 7%-70%.

[0075] As an example, k1 can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%.

[0076] In some embodiments, k1 may be 2%-26%.

[0077] As an example, q1 is 7%, 8%, 9%, 10%, 13%, 15%, 17%, 20%, 23%, 25%, 27%, 30%, 33%, 35%, 37%, 40%, 43%, 45%, 47%, 50%, 53%, 55%, 57%, 60%, 63%, 65%, 67% or 70%.

[0078] In some embodiments, q1 may be 10%-23%.

[0079] When k1 and q1 are within the above ranges, the first lithium replenisher can provide a higher lithium replenishment gram capacity.

[0080] In some embodiments, k2 is 15%-70%, and q2 is 8%-20%.

[0081] As an example, k2 can be 15%, 17%, 20%, 23%, 25%, 27%, 30%, 33%, 35%, 37%, 40%, 43%, 45%, 47%, 50%, 53%, 55%, 57%, 60%, 63%, 65%, 67% or 70%.

[0082] In some embodiments, k2 may be 35%-50%.

[0083] As an example, q2 can be 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19% or 20%.

[0084] In some embodiments, q2 may be 8%-15%.

[0085] For lithium supplements, as the lithium mass fraction increases, the lithium supplement capacity increases accordingly, and the basicity of the supplement also increases accordingly. Correspondingly, as the carbon mass fraction increases, the basicity of the supplement decreases accordingly, and the lithium supplement capacity decreases accordingly. When k2 and q2 are within the above ranges, the second lithium supplement can effectively alleviate the strong basicity of the first lithium supplement, making the acidity and alkalinity of the lithium supplement additive weakly alkaline.

[0086] The mass fraction of lithium in the first lithium supplement and the second lithium supplement can be tested using methods known in the art. As an example, an inductively coupled plasma optical emission spectrometer (ICP-OES) can be used for testing. Specifically, the test conditions are as follows: the sample to be tested must be liquid. If the sample to be tested contains solid particles, acid digestion must be added, or solid particles must be removed by filtration. The range of the element to be tested must be within the range of the standard curve. If it exceeds the range, the sample must be diluted. The main operating procedures are: 1. Test the standard curve; 2. Dilute the sample to be tested; 3. Test the diluted sample; 4. Calculate and process the data to obtain the concentration of the element to be tested.

[0087] The mass fraction of carbon in both the first and second lithium supplements can be measured using methods known in the art. For example, an infrared sulfur-carbon analyzer can be used. Specifically, the sample to be tested is burned in a high-temperature furnace with oxygen to generate and release CO2 gas, which is used to separate carbon from metal elements and their compounds. The CO2 content is then measured and converted to the carbon content of the sample to be tested.

[0088] In some embodiments, the mass fraction of the first lithium supplement agent in the lithium supplement additive is m1, the mass fraction of the second lithium supplement agent in the lithium supplement additive is m2, and m1:m2 is less than or equal to (10:1).

[0089] As examples, m1:m2 can be (1:1), (1.5:1), (2:1), (2.5:1), (3:1), (3.5:1), (4:1), (4.5:1), (5:1), (5.5:1), (6:1), (6.5:1), (7:1), (7.5:1), (8:1), (8.5:1), (9:1), (9.5:1) or (10:1).

[0090] In some embodiments, when the first lithium supplement agent and the second lithium supplement agent are directly added to the positive electrode slurry, m1:m2 can be (5:1)-(10:1). At this time, the lithium supplement additive has a higher lithium supplement gram capacity and is weakly alkaline as a whole. The lithium supplement additive has less adverse effects on the binder, can reduce the gelation of the positive electrode slurry, and improve the processing performance of the positive electrode slurry.

[0091] In some embodiments, when the second lithium supplement agent forms a second coating layer on the surface of the first core, m1:m2 can be less than or equal to 10. The lithium supplement additive is weakly alkaline as a whole and close to neutral. The lithium supplement additive has almost no adverse effect on the binder, thereby increasing the content of the lithium supplement additive in the positive electrode slurry, thereby effectively increasing the lithium supplement gram capacity that can be released by the lithium supplement additive.

[0092] In some embodiments, the Dv50 particle size of the first lithium supplement is d1, the Dv50 particle size of the second lithium supplement is d2, and d1 / d2 is greater than or equal to 2.

[0093] When d1 / d2 is greater than or equal to 2, when the second lithium supplement agent is coated on the surface of the first lithium supplement agent to form a second coating layer, it helps to form the coating layer; and the addition of the lithium supplement additive can improve the porosity of the positive electrode sheet. Specifically, when the lithium supplement agent in the positive electrode active material layer releases lithium ions during the first charging process, only a small amount of metal salt remains in the remaining part, resulting in larger gaps in the pore structure originally occupied by the lithium supplement agent; or due to decomposition and gas production, the pore structure originally occupied by the lithium supplement agent is completely vacant, thereby improving the porosity of the positive electrode sheet.

[0094] In some embodiments, d1 is 5 μm to 15 μm, and / or d2 is 1 μm to 5 μm.

[0095] As an example, d1 may be 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 13.5μm, 14μm, 14.5μm or 15μm.

[0096] As an example, d2 may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, or 5 μm.

[0097] When d1 is 5 μm-15 μm, and / or d2 is 1 μm-5 μm, the volume average particle size of the lithium supplement additive is larger than the volume average particle size of the positive electrode active material, for example, larger than the volume average particle size of lithium iron phosphate. As a result, the stacking structure of the lithium supplement additive differs from that of the positive electrode active material. Therefore, after the lithium supplement additive releases lithium ions during the initial charge, the remaining portion can form larger pores, further increasing the porosity of the positive electrode sheet.

[0098] In some embodiments, the Dv10 particle size of the first lithium supplement is d3, the Dv10 particle size of the second lithium supplement is d4, and d3 / d4 is greater than or equal to 4.

[0099] When d3 / d4 is greater than or equal to 4, it is beneficial to improve the processing performance after the first lithium supplement agent and the second lithium supplement agent are mixed.

[0100] In some embodiments, d3 is 1 μm to 10 μm, and / or d4 is 0.2 μm to 1 μm.

[0101] As an example, d3 may be 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm, or 10 μm.

[0102] As an example, d4 may be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1.0 μm.

[0103] In some embodiments, the purity of the lithium-supplementing additive is greater than or equal to 90%.

[0104] As an example, the purity of the lithium supplement additive may be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%.

[0105] When the purity of the lithium replenishing additive is within the above range, the inert impurities on the surfaces of the first lithium replenishing agent and the second lithium replenishing agent, such as LiOH, Li2CO3 or other lithium-containing oxides, copper-containing oxides, nickel-containing oxides, etc., are relatively small, and the lithium replenishing effect of the lithium replenishing agent is better.

[0106] When the purity of the lithium supplementing additive approaches 100%, the process steps and costs required for purification will increase significantly. As an example, the purity of the lithium supplementing additive can be 90%-97%.

[0107] In some embodiments, the initial delithiation capacity of the aforementioned lithium supplement additive may be greater than 400 mAh / g; the decomposition potential of the lithium supplement additive, ie, the potential for releasing lithium ions, is 2.0V-4.5V.

[0108] When the decomposition potential of the lithium supplement additive is 2.0V-4.5V, the lithium supplement additive is not easy to react with air / water, resulting in over-discharge; at the same time, when the lithium supplement additive decomposes to release lithium ions, the electrolyte will not decompose and produce gas due to excessively high voltage.

[0109] As an example, when the positive electrode active material is lithium iron phosphate, the decomposition potential of the lithium supplement material may be 3.0V-3.75V.

[0110] In some embodiments, the first lithium supplement agent and the second lithium supplement agent may be pre-mixed and then added to the positive electrode slurry, or the first lithium supplement agent and the second lithium supplement agent may be added to the positive electrode slurry separately and then the positive electrode slurry is stirred or mixed.

[0111] In some embodiments, the mixing process may include a ball milling process, and the ball milling process satisfies at least one of the following conditions: the ball milling speed is 600 rpm-1200 rpm; the ball milling time is 1 hour-4 hours; the grinding aid for the ball milling process includes graphite; and the mass ratio of the first lithium supplement agent to the second lithium supplement agent in the mixture is (5:1)-(10:1).

[0112] The second lithium supplement agent can be coated on the surface of the first lithium supplement agent through ball milling to form a second coating layer, thereby obtaining a lithium supplement additive through coating. When the second lithium supplement agent includes a porous carbon support and a second core, and the second core is located within the pore structure of the porous carbon support, the process of forming a carbon material coating layer on the surface of the first core of the first lithium supplement agent can be omitted. The second lithium supplement agent is fixed to the surface of the first core through ball milling, and the first and second cores share the coating layer of the second lithium supplement agent.

[0113] In a second aspect, the present application provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector. The positive electrode active material layer comprises a positive electrode active material and a lithium replenishing additive, wherein the lithium replenishing additive comprises the aforementioned lithium replenishing additive. Thus, the positive electrode sheet possesses all the features and advantages of the aforementioned lithium replenishing additive, which will not be further elaborated here.

[0114] In some embodiments, the mass fraction of the lithium supplementing additive in the positive electrode active material layer is 0.1%-10%. In some embodiments, the mass fraction of the lithium supplementing additive in the positive electrode active material layer is 2%-7%.

[0115] As an example, the mass fraction of the lithium supplement additive in the positive electrode active material layer can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

[0116] When the mass fraction of the lithium replenishing additive in the positive electrode active material layer is 0.1%-10%, the positive electrode active material layer contains an appropriate amount of lithium replenishing agent, which can not only replenish the active lithium ion loss during the battery charging and discharging process, but also prevent the positive electrode active material layer from having too little positive electrode active material due to the high content of the lithium replenishing agent, thereby causing insufficient reversible lithium insertion vacancies in the positive electrode active material layer and resulting in too low an energy density of the battery.

[0117] When the lithium-supplementing additive in the positive electrode active material layer releases lithium ions during the initial charge, only a small amount of metal salt remains, resulting in larger gaps in the pore structure originally occupied by the lithium-supplementing additive. Alternatively, decomposition and gas production completely empty the pore structure originally occupied by the lithium-supplementing additive, thereby increasing the porosity of the positive electrode sheet. When the negative electrode sheet expands during charging, the pore structure in the positive electrode sheet is squeezed, relieving the expansion stress on the negative electrode sheet, reducing the extrusion of electrolyte inside the negative electrode sheet, and facilitating electrolyte reflux in the negative electrode sheet, thereby improving the electrolyte's wettability to the negative electrode sheet.

[0118] In some embodiments, the mass fraction of the first lithium replenisher in the positive electrode active material layer is 0.1%-10%; the mass fraction of the second lithium replenisher in the positive electrode active material layer is 0.1%-5%.

[0119] As an example, the mass fraction of the first lithium supplement agent in the positive electrode active material layer can be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%.

[0120] As an example, the mass fraction of the second lithium supplement agent in the positive electrode active material layer may be 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

[0121] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0122] In some embodiments, the positive electrode 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 material base and a metal layer formed on at least one surface of the polymer material base. 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 material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0123] In some embodiments, when the battery is a lithium ion battery, the positive electrode active material may be a positive electrode active material for lithium ion batteries known in the art.

[0124] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The modified compounds of the above materials may be modified by doping and / or surface coating the materials.

[0125] The battery's charge and discharge processes involve the intercalation and deintercalation of lithium, leading to different molar Li contents at different discharge states. The molar Li contents listed in this application for the positive electrode active materials refer to the initial state of the material, i.e., the state before addition. When the positive electrode active material is used in a battery system, the molar Li content will change after charge and discharge cycles.

[0126] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0127] In some embodiments, the positive active material layer may further optionally include a binder.

[0128] As an example, the binder may include at least one of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, hydrogenated nitrile rubber, polytetrafluoroethylene, and polyacrylic acid, thereby improving the bonding strength between the positive electrode active material layer and the positive electrode current collector.

[0129] In some embodiments, the positive active material layer may further optionally include a conductive agent.

[0130] As an example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, lithium supplement, conductive agent, binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, and the positive electrode slurry is coated on the positive electrode current collector. After drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0132] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the positive electrode active material, conductive agent, binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, coating the positive electrode slurry on the positive electrode current collector, and forming a positive electrode active material layer after drying, cold pressing and other processes. Then, the lithium supplement agent is composited with the positive electrode active material layer by spraying, secondary coating and other methods on the surface of the positive electrode active material layer.

[0133] In some embodiments, the solid content of the positive electrode slurry is 50%-70%.

[0134] As an example, the solid content of the positive electrode slurry can be 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%.

[0135] When the solid content of the positive electrode slurry is 50%-70%, the solid content of the positive electrode slurry is relatively moderate, which can not only dissolve the positive electrode active material and other components more fully, but also reduce the amount of solvent in the positive electrode slurry, reduce costs, and also make the positive electrode slurry have appropriate fluidity, which is convenient for the coating process.

[0136] In some embodiments, the solid content of the positive electrode slurry is 60%-65%.

[0137] In a third aspect of the present application, a battery is provided, comprising the aforementioned positive electrode sheet. Thus, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0138] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0139] In some embodiments, the battery further comprises: a negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer located at least on one side of the negative electrode current collector, the negative electrode active material layer comprising a negative electrode active material, the negative electrode active material comprising at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. However, the present application is not limited to these materials; other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0140] When a battery is charging, lithium ions are released from the positive electrode active material, diffuse through the electrolyte, migrate to the surface of the negative electrode plate, and then embed into the negative electrode active material. When the battery is discharging, lithium ions are released from the negative electrode active material, diffuse through the electrolyte, migrate to the surface of the positive electrode plate, and then embed into the positive electrode active material. During the charge and discharge process, the negative electrode active material will expand in volume due to the embedding of lithium ions and shrink in volume due to the release of lithium ions. As a result, the negative electrode active material will continue to change in volume during the charge and discharge cycle of the battery. Generally, negative electrode active materials with higher gram capacity will experience greater volume changes during the charge and discharge process. For example, negative electrode active materials with larger volume expansion during the charge and discharge cycle, such as silicon-based negative electrode active materials, will experience a significant volume effect during the charge and discharge cycle. This causes the electrolyte inside the negative electrode plate to be gradually squeezed out along one side of the negative electrode plate, resulting in reduced wettability of the electrolyte to some areas of the negative electrode plate, ultimately leading to lithium plating, which significantly affects the cycle life and capacity of the battery cell.

[0141] In the present application, by optimizing the design of the lithium-replenishing additive in the positive electrode plate, when the lithium-replenishing additive in the positive electrode active material layer releases lithium ions during the first charging process, only a small amount of metal salt remains in the remaining part, causing the pore structure originally occupied by the lithium-replenishing additive to have larger gaps; or due to decomposition and gas production, the pore structure originally occupied by the lithium-replenishing additive is completely vacant, thereby improving the porosity of the positive electrode plate. When the negative electrode plate expands during the charging process, the pore structure in the positive electrode plate will be squeezed, relieving the expansion stress on the negative electrode plate, reducing the extrusion of the electrolyte inside the negative electrode plate, and improving the wettability of the electrolyte to the negative electrode plate. The use of high-gram capacity negative electrode active materials can effectively improve the energy density of the battery, and the improvement of the wettability of the electrolyte to the negative electrode plate also greatly improves the cycle performance of the battery.

[0142] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0143] 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 base layer and a metal layer formed on at least one surface of the polymer base material. 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 base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0144] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0145] In some embodiments, the negative electrode active material layer may further include a conductive agent, which includes at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0146] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0147] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) 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.

[0148] [Electrolytes]

[0149] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0150] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0151] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0152] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0153] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0154] [Isolation film]

[0155] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any porous separator with good chemical and mechanical stability can be selected.

[0156] In some embodiments, the material of the separator includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0157] The battery of the present application includes a battery cell form, a battery module form and a battery pack form. The battery, battery module and battery pack of the present application are described below with reference to the accompanying drawings as appropriate.

[0158] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0159] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0160] In some embodiments, the battery outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the battery outer packaging may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0161] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG1 shows a battery cell 5 of a square structure as an example.

[0162] In some embodiments, referring to Figure 2, the outer packaging may include a shell 51 and a top cover assembly 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell can be one or more, and those skilled in the art can select according to specific actual needs.

[0163] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0164] FIG3 shows an example battery module 4. Referring to FIG3 , in the battery module 4, multiple battery cells may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple battery cells may be secured together using fasteners.

[0165] Optionally, the battery module 4 may further include a housing having an accommodation space, and a plurality of battery cells are accommodated in the accommodation space.

[0166] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0167] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0168] In a fourth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here.

[0169] Batteries, battery modules, and battery packs can be used as power sources or energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0170] As an electrical device, a battery, battery module or battery pack can be selected according to its usage requirements.

[0171] Figure 6 shows an example of an electric device. This device can be a pure electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0172] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0173] The present invention will be described below by way of specific examples. It should be noted that the following examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, they are determined according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments not specified by manufacturer are all commercially available conventional products.

[0174] Example 1

[0175] Preparation of positive electrode:

[0176] The positive electrode active material LiFePO4 (LFP), the conductive agent acetylene black, the binder PVDF, and the lithium supplement additive are mixed in an N-methylpyrrolidone solvent (NMP) system in a weight ratio of 95:1:2:2. After thorough stirring and mixing, a positive electrode slurry with a solid content of 60% is obtained. The positive electrode slurry is coated on Al foil, dried, and cold pressed to obtain a positive electrode sheet. The Dv50 particle size of the LFP particles is 1.2μm. The surface density of the positive electrode slurry on the surface of the positive electrode sheet is 20g / cm 2 .

[0177] The lithium supplement additive includes a first lithium supplement and a second lithium supplement, and the mass ratio of the first lithium supplement to the second lithium supplement is 9:1.

[0178] The synthesis method of the first lithium supplement is as follows:

[0179] Fe2O3 and Li2O were solid-phase mixed at a Li:Fe molar ratio of 5.12:1, heated to 300°C under an argon atmosphere, and held for 6 hours to obtain a first core of lithium ferrite. A nano-alumina coating agent was then added, wherein the mass ratio of alumina to lithium ferrite was 1:100. The mixture was mixed using a high-speed mixer and then held at 900°C for 8 hours to obtain lithium ferrite with a surface coating of alumina. The alumina-coated lithium ferrite obtained above was then crushed. After crushing, dopamine (DA, C8HNO2) was mixed with the lithium ferrite at a mass ratio of 1:28, allowing the dopamine to polymerize on the lithium ferrite surface and form a polydopamine (PDA) nanofilm. The PDA-coated material was then held at 900°C under an argon atmosphere for 8 hours to obtain a first lithium supplement, wherein the first core of the first lithium supplement was lithium ferrite, the first sub-coating layer was Al2O3, and the second sub-coating layer was a carbon material.

[0180] The synthesis method of the second lithium supplement is as follows:

[0181] Take crystals of squaric acid (CAS: 2892-51-5), dissolve them in water at a solid-liquid ratio of 1:2, and press Li + :C4O4 2- Li was added at a molar ratio of 2:1 + A lithium hydroxide solution with a concentration of 65g / L was stirred for 2 hours to obtain a second core, which was then mixed with a carbon nanotube solution with a mass fraction of 1wt% at a mass ratio of 6:1. After ultrasonication for 30 minutes, the mixture was maintained at 150°C in an oven for 8 hours for evaporation and crystallization to obtain a second lithium supplement.

[0182] Preparation of negative electrode sheet:

[0183] The negative electrode active material artificial graphite, conductive agent acetylene black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) were mixed in a deionized water solvent system at a weight ratio of 96.5:0.7:1.8:1, and then stirred and mixed to obtain a negative electrode slurry. The negative electrode slurry was coated on a Cu foil, dried, and cold pressed to obtain a negative electrode sheet. The surface density of the negative electrode slurry on the surface of the negative electrode sheet was 15g / cm 2 .

[0184] Battery assembly:

[0185] A PE / PP porous polymer film with a thickness of 12 μm was used as the isolation membrane.

[0186] Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a mass ratio of 50 / 50, and 1.1 M LiPF6 lithium salt was dissolved to form an electrolyte.

[0187] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrodes to provide isolation. The sheets are then wound to form a bare cell. The bare cell is then placed in an outer packaging, filled with the prepared electrolyte, and sealed to form a battery.

[0188] The differences between the first lithium supplement agent of Example 2-11 and Comparative Example 1-2 and Example 1 are shown in Table 1, and the differences between the second lithium supplement agent are shown in Table 2.

[0189] In Example 2, the amount of dopamine added was adjusted so that the mass ratio of dopamine to lithium ferrite was 1:15.

[0190] The synthesis method of the second lithium supplement in Example 3 is as follows: ketomalonic acid (HO)2C(COOH)2 is extracted with 100% ethanol, and then ketomalonic acid is reacted with LiOH in a mass ratio of 1:2.1. The product is centrifuged and washed three times with ethanol to remove excess alkali. Subsequently, a second core Li2C3O5 is obtained by vacuum dehydration at 165°C. The second core is mixed with a carbon nanotube solution with a mass fraction of 1 wt% at a mass ratio of the second core to the carbon nanotubes of 6:1. After ultrasonication for 30 minutes, the mixture is maintained at 150°C in an oven for 8 hours for evaporation and crystallization to obtain the second lithium supplement.

[0191] In Example 4, the second lithium supplement agent is coated on the surface of the first lithium supplement agent, specifically comprising: ball milling the first lithium supplement agent and the second lithium supplement agent at a mass ratio of 9:1, at a ball milling speed of 1000 rpm, for 3 hours, and using graphite as a grinding aid.

[0192] In Examples 5-9, the masses of the lithium supplement additive and the positive electrode active material in the positive electrode slurry were adjusted accordingly, the sum of the mass fraction of the lithium supplement additive and the mass fraction of the positive electrode active material was 97%, and the mass fraction of the conductive agent and the mass fraction of the binder remained unchanged, which was the same as in Example 1.

[0193] The difference between Example 10 and Example 1 is that the first core is Li2C2O4.

[0194] The difference between Example 11 and Example 1 is that the first core is Li2NiO2.

[0195] The lithium supplement additive in Comparative Example 1 only uses the first lithium supplement agent.

[0196] The lithium supplement additive in Comparative Example 2 only uses the second lithium supplement agent.

[0197] Table 1

[0198] Table 2

[0199] The following tests were performed on the batteries in Examples 1-11 and Comparative Examples 1-2. The test results are shown in Table 3.

[0200] 1. Charge and discharge capacity test: At 25°C, charge the battery at a constant current of 0.33C to a charge termination voltage of 3.65V, then charge it at a constant voltage of 0.05C to measure the charge capacity E c0 , use E c0 Divide by the mass of the positive electrode active material in the battery to get the charge specific capacity. That is: Charge specific capacity (mAh / g) = 1st cycle charge capacity / mass of positive electrode active material.

[0201] Take the above charged battery and discharge it at a constant current of 0.33C at 25℃ until the discharge end voltage is 2.5V. The discharge capacity is E d0 Use E d0 Divide by the mass of the positive electrode active material in the battery to get the discharge specific capacity. That is: discharge specific capacity (mAh / g) = first cycle discharge capacity / mass of positive electrode active material.

[0202] The above-mentioned charge specific capacity and discharge specific capacity tests were repeated 5 times and the average value was taken.

[0203] 2. Calculation of battery volume energy density:

[0204] Measure the internal dimensions of the battery case (length a, width b, and height c). Charge each battery at 25°C at a 1C rate to a voltage of 3.65V, then discharge at a 1C rate to a voltage of 2.5V. Measure the discharge energy, S0.

[0205] Battery volume energy density = S0 / (a×b×c)

[0206] 3. Stability of cathode slurry:

[0207] The prepared positive electrode slurry was placed in a beaker and sealed with plastic wrap. After standing for 24 hours, the following observations were made:

[0208] (1) Take out the positive electrode slurry that has been left to stand and record the front mark of the beaker and the sealing condition of the beaker.

[0209] (2) Open the plastic wrap and gently move the surface of the positive electrode slurry with a steel ruler to check whether there is any abnormality on the surface of the positive electrode slurry and whether the color has changed.

[0210] (3) Slowly insert the steel ruler into the slurry and gently move it up and down to preliminarily determine the viscosity of the positive electrode slurry.

[0211] (4) Use a steel ruler to scoop out part of the slurry, check the fluidity of the positive electrode slurry, and take photos to record.

[0212] The gel state of the positive electrode slurry is divided into the following levels:

[0213] a. Mild gel: The slurry has good fluidity, but there is obvious reflection on the liquid surface, and the slurry flow line is protruding from the liquid surface.

[0214] b. Moderate gel: The slurry has poor fluidity and is flocculent; the slurry is flocculent but has no solid properties; there are no jelly lumps.

[0215] c. Severe gelation: The slurry has no fluidity and is jelly-like; the slurry is solid, has no fluidity, and can be picked up in one piece.

[0216] d. No gelling: The slurry has good fluidity and has no other abnormalities as mentioned above.

[0217] Table 3

[0218] As can be seen from Table 2, the lithium-supplementing additive in Comparative Example 1 only uses the first lithium-supplementing agent with a relatively strong alkalinity, which leads to serious gelation in the positive electrode slurry, loss of fluidity of the slurry, unstable quality in the coating process, poor process consistency and other problems, which seriously affect the production efficiency. Among them, the mass fraction of the lithium-supplementing additive in the positive electrode slurry of Example 5 is relatively small, and the lithium-supplementing additive can only partially make up for the lithium ion loss in the first cycle of charge and discharge, resulting in a low first cycle charge capacity of the battery and a low volume energy density of the battery. The mass fraction of the lithium-supplementing additive in the positive electrode slurry in Examples 6-9 is relatively high, and the lithium-supplementing additive can effectively make up for the lithium ion loss in the first cycle of charge and discharge, thereby improving the first cycle charge capacity of the battery. At the same time, due to the large proportion of the lithium-supplementing additive in the positive electrode active material layer, the lithium-supplementing additive can hardly provide discharge capacity, thereby making the first cycle discharge capacity and volume energy density of the battery relatively low.

[0219] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium supplement additive, wherein: include: A first lithium supplement, wherein the first lithium supplement comprises a first core, and the first core satisfies the chemical formula Li a M b O c , wherein a is 1.5-6, b is 0-2, c is 1-6, and the M element includes at least one of magnesium, calcium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, tin, silicon, carbon, and boron; A second lithium supplement, wherein the second lithium supplement comprises a second core, and the second core satisfies the chemical formula Li d C e O f , d is 1.5-6, e is 3-5, f is 1.5-6, The mass fraction of the first lithium supplement in the lithium supplement additive is m1, the mass fraction of the second lithium supplement in the lithium supplement additive is m2, and m1:m2 is less than or equal to (10:1).

2. The lithium supplement additive according to claim 1, wherein The mass fraction of the carbon element in the first lithium supplement is k1, the mass fraction of the lithium element in the first lithium supplement is q1, and k1 / q1 is 0-2.

3. The lithium supplement additive according to claim 1 or 2, wherein: The mass fraction of the carbon element in the second lithium supplement is k2, the mass fraction of the lithium element in the second lithium supplement is q2, and k2 / q2 is greater than or equal to 2.

5.

4. The lithium supplement additive according to claim 1, wherein The first lithium supplement includes a first core and a first coating layer, wherein the first coating layer covers at least a portion of the surface of the first core, and the first coating layer includes at least one of metal fluoride, metal oxide, metal phosphate, ternary lithium salt, carbon material, poly 3,4-ethylenedioxythiophene, and polypyrrole.

5. The lithium supplement additive according to claim 1, wherein: The second lithium supplement comprises a porous carbon support and a second core, wherein the second core is located in the pore structure of the porous carbon support.

6. The lithium supplement additive according to claim 4 or 5, wherein: The particle size of the first lithium supplement agent is larger than that of the second lithium supplement agent, at least a portion of the surface of the first core has a second coating layer, and the second coating layer includes the second lithium supplement agent.

7. The lithium supplement additive according to claim 2, wherein: k1 is 0%-30%, and q1 is 7%-70%.

8. The lithium supplement additive according to claim 3, wherein: k2 is 15%-70%, and q2 is 8%-20%.

9. The lithium supplement additive according to any one of claims 1 to 8, wherein: The first kernel satisfies at least one of the following conditions: When a is 2 and c is 2, M includes at least one of Ni, Co, Fe, Mn, Zn, Mg, Ca, and Cu; When a is 2 and c is 3, M includes at least one of Si, Ni, Co, Fe, Mn, Sn, and Cr; When a is 2 and c is 4, M includes at least one of C, Fe, Mn, Cr, and Nb; When a is 3 and c is 4, M includes at least one of Co, Fe, Mn, Cr, V, Mo, and Nb; When a is 5 and c is 4, M includes at least one of Ni, Co, Fe, Mn, Cr, and Mo; When a is 6 and c is 4, M includes at least one of Ni, Co, Mn, Fe, Cu, and Ru.

10. The lithium supplement additive according to any one of claims 1 to 9, wherein: The second core includes at least one of Li2C3O5, Li2C4O4, and Li2C4O6.

11. The lithium supplement additive according to any one of claims 1 to 10, wherein: The Dv50 particle size of the first lithium supplement is d1, the Dv50 particle size of the second lithium supplement is d2, and d1 / d2 is greater than or equal to 2.

12. A positive electrode sheet, comprising a positive electrode current collector and a positive electrode active material layer located on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material and a lithium supplement additive, the lithium supplement additive comprising the lithium supplement additive according to any one of claims 1 to 11.

13. The positive electrode sheet according to claim 12, wherein: The mass fraction of the lithium supplement additive in the positive electrode active material layer is 0.1%-10%.

14. The positive electrode sheet according to claim 12 or 13, wherein: The positive electrode active material layer further includes a binder, and the binder includes at least one of polyvinylidene fluoride, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, hydrogenated nitrile rubber, polytetrafluoroethylene, and polyacrylic acid.

15. A battery, wherein: Comprising the positive electrode sheet as described in any one of claims 12 to 14.

16. An electrical device, wherein: Comprising the battery of claim 15.

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