Lithium supplement additive, positive pole piece, battery and electric device

Abstract

The invention discloses a lithium supplement additive, a positive pole piece, a battery and a power utilization device, the lithium supplement additive comprises: a first lithium supplement agent, the first lithium supplement agent comprises a first core, the first core satisfies a chemical formula LiaMbOc, a is 1.5-6, b is 0-2, c is 1-6, and a is 0-2; 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; the second lithium supplement agent comprises a second inner core, the second inner core meets the chemical formula LidCeOf, d is 1.5-6, e is 3-5, 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. Therefore, poor processing such as slurry gel caused by particle aggregation of the lithium supplement additive can be reduced, and the lithium supplement effect of the lithium supplement additive can be improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular, 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 good rate performance. How to further improve the energy density and cycle life of lithium-ion batteries has also become a research hotspot in the battery field. Lithium loss is the direct cause of battery degradation. For example, during the first charge and discharge process of the battery, the electrolyte will form a solid electrolyte interface film (SEI film) on the surface of the negative electrode. The formation of the SEI film will consume a large amount of active lithium ions, which will lead to a low coulombic efficiency of the first cycle of the battery. During the charge and discharge cycle of the battery, the cracking and crushing of the positive electrode active material particles, the thickening and repair of the SEI film, etc. will consume active lithium ions, which will cause a significant decrease in the battery cycle performance. The first cycle efficiency, energy density and cycle life of lithium batteries can be improved by adding lithium supplement additives. However, the current lithium supplement additives are in the early development stage, and there are still many deficiencies in production and application.

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

[0004] 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, 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). In this way, the agglomeration of lithium supplement additive particles, the resulting processing defects such as slurry gel, etc. can be reduced, and the lithium supplement effect of the lithium supplement additive can be improved.

[0005] 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. Thus, the lithium supplement effect of the lithium supplement additive can be further improved.

[0006] 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. In this way, the particle agglomeration of the lithium supplement additive, which may lead to poor processing such as slurry gel, can be reduced, and the lithium supplement effect of the lithium supplement additive can be improved. In this way, the lithium supplement effect of the lithium supplement additive can be further improved.

[0007] 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. Thus, the alkalinity of the first lithium supplement can be reduced.

[0008] In some embodiments, the second lithium supplement agent includes a porous carbon support and a second core, and the second core is located in the pore structure of the porous carbon support, thereby improving the conductivity of the second lithium supplement agent.

[0009] In some embodiments, the particle size of the first lithium supplement is larger than that of the second lithium supplement, at least part of the surface of the first core has a second coating layer, and the second coating layer includes the second lithium supplement. Thus, the manufacturing process of the first lithium supplement can be simplified and the alkalinity of the first lithium supplement can be reduced.

[0010] In some embodiments, k1 is 0%-30%, and q1 is 7%-70%. Thus, the first lithium supplement has a higher lithium supplement gram capacity.

[0011] In some embodiments, k2 is 15%-70%, and q2 is 8%-20%. Thus, the second lithium supplement has both high conductivity and low alkalinity.

[0012] 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; when a is 6 and c is 4, M includes at least one of Ni, Co, Mn, Fe, Cu, and Ru. Thus, the lithium supplement gram capacity of the first lithium supplement can be further improved.

[0013] In some embodiments, the second core includes at least one of Li2C3O5, Li2C4O4, and Li2C4O6. Thus, the alkalinity of the second lithium supplement can be further reduced.

[0014] 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.

[0015] In the second aspect of the present application, the present application proposes 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 supplement additive, wherein the lithium supplement additive comprises the aforementioned lithium supplement additive. Thus, the positive electrode plate has all the features and advantages of the aforementioned lithium supplement additive, which will not be described in detail here.

[0016] 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.

[0017] In some embodiments, 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. Thus, the bonding effect between the positive electrode active material layer and the positive electrode current collector can be improved.

[0018] In the third aspect of the present application, the present application proposes a battery, comprising the aforementioned positive electrode sheet. Therefore, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0019] In a fourth aspect of the present application, the present application proposes an electrical device, comprising the aforementioned battery. Therefore, 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

[0020] 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:

[0021] Figure 1 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0022] Figure 2 yes Figure 1 An exploded view of a battery cell according to an embodiment of the present application is shown;

[0023] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application;

[0024] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0025] Figure 5 yes Figure 4 An exploded view of a battery pack according to an embodiment of the present application is shown;

[0026] Figure 6 Schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0027] Description of reference numerals:

[0028] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell;

[0029] 51 shell; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0030] Hereinafter, the lithium supplement additive and its preparation method, positive electrode plate, battery, and electric device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there are 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 descriptions 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.

[0031] " Scope " disclosed in the present application is limited in the form of lower limit and upper limit, and a 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 a special range. The scope limited in this way can be to include end values ​​or not include end values, and can be combined arbitrarily, 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 a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it 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.

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

[0033] 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.

[0034] 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 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).

[0035] 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 indicating the number of the indicated technical features. "First feature" and "second feature" may include one or more of the features.

[0036] In the description of the present application, “plurality” means two or more.

[0037] In the description of the present 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 examples and may be any technical feature connected by "and / or" in the present application.

[0038] On the one hand, lithium replenishers can make up for the loss of active lithium ions caused by the formation of SEI during the first charge and discharge process, so that the battery has enough reversible active lithium ions in the subsequent cycle process, thereby improving the energy density of the battery; 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 cycle performance of the battery. 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 the formation of SEI and other phenomena. In order to improve the lithium replenishment effect, lithium-rich materials with a high lithium ion content are usually used as lithium replenishment additives.

[0039] 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.

[0040] In the present application, by mixing a first alkaline lithium supplement agent with a second acidic lithium supplement agent, the composite lithium supplement additives are weakly alkaline. When the mixed lithium supplement additives are mixed with an acidic binder, the alkalinity of the lithium supplement additives is relatively weak, so the damage to the acidic binder is less, 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 additives can also better exert their lithium supplement performance and improve the battery cycle performance.

[0041] 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.

[0042] As an example, a can be 1.5, 2, 3, 4, 5 or 6.

[0043] As an example, b can be 0, 1 or 2.

[0044] When b is 0, the first core is a binary lithium-containing compound. As an example, the binary lithium-containing compound may include Li2O, Li2O2.

[0045] As an example, c can be 1, 2, 3, 4, 5 or 6.

[0046] The addition of the first lithium supplement agent can effectively increase the lithium supplement gram capacity of the lithium supplement additive.

[0047] As an example, the first core may include Li2C2O4, Li2CO3, Li2SiO3, or Li3BO3.

[0048] Unless otherwise specified, in the above chemical formula, when M is more than two elements, the above limitation on the numerical range of b is not only a limitation on the stoichiometric number of each element as M, but also a limitation on the sum of the stoichiometric numbers of each element as M. For example, when M includes more than two elements M1, M2, M3...Mn, the stoichiometric numbers b1, b2, b3...bn of M1, M2, M3...Mn must each fall within the numerical range of b defined in this application, and the sum of b1, b2, b3...bn must also fall within the numerical range.

[0049] 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 supplement gram capacity of the first lithium supplement can be further improved. 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 the air. By combining different elements, the decomposition potential of the core can also be regulated, which helps it to better release active lithium ions.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] As an example, d may be 1.5, 2, 3, 4, 5, or 6.

[0054] As an example, e can be 3, 4 or 5.

[0055] As an example, f may be 1.5, 2, 3, 4, 5, or 6.

[0056] 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.

[0057] In some embodiments, the first lithium replenisher and the second lithium replenisher can be added to the positive electrode slurry separately and blended in the positive electrode slurry, or the first lithium replenisher and the second lithium replenisher can be pre-blended and then added to the positive electrode slurry.

[0058] In some embodiments, the second inner core may include at least one of Li2C3O5, Li2C4O4, and Li2C4O6.

[0059] Lithium supplement is Li x C y O z For example, based on the acid-base proton theory, lithium belongs to alkali metals, and lithium oxalate is a strong base and weak acid salt, which is alkaline. 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 gram 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 gram 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 gram 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, and the defects such as gel of the positive electrode slurry caused by the excessive alkalinity of the lithium supplement additive are reduced. By using the first lithium supplement agent and the second lithium supplement agent as lithium supplement additives together, 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.

[0060] 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.

[0061] 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.

[0062] As an example, k2 / q2 can be 2.5-12. 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.

[0063] 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.

[0064] 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.

[0065] In some embodiments, the first coating layer may include a first sub-coating layer and a second sub-coating layer that are stacked, 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.

[0066] 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.

[0067] When the first coating layer includes a carbon material, the conductivity of the first lithium supplement can be effectively improved.

[0068] 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 a carbon atom and two oxygen atoms, the electron cloud density near the carbon atoms is low, the 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, thereby improving the problems of 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.

[0069] In some embodiments, the second lithium supplement 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.

[0070] As an example, the second core can be recrystallized in the pore structure of the porous carbon carrier by a liquid phase synthesis method, thereby obtaining a second lithium supplement having the second core located in the pore structure of the porous carbon carrier.

[0071] By disposing the second inner core in the pore structure of the porous carbon carrier with good conductivity, the conductivity of the second lithium supplement agent can be effectively improved, which is helpful for releasing the lithium supplement capacity.

[0072] In some embodiments, the porous carbon support includes at least one of activated carbon, carbon nanotubes, carbon nitride, and carbon nitride nanotubes.

[0073] In some embodiments, the second lithium supplement agent can be coated on the surface of the first lithium supplement agent, that is, 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, at least part of the surface of the first core has a second coating layer, and the second coating layer includes the second lithium supplement agent, that is, the second lithium supplement agent covers at least part of the surface of the first core to form a second coating layer.

[0074] When the second lithium supplement is disposed on the surface of the first lithium supplement in the form of a coating layer, the first lithium supplement can share the porous carbon carrier of the second lithium supplement with the second lithium supplement to improve the conductivity of the first lithium supplement, thereby eliminating the need to form a carbon material coating layer on the surface of the first core.

[0075] In some embodiments, k1 is 0%-30%, and q1 is 7%-70%.

[0076] 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%.

[0077] In some embodiments, k1 may be 2%-26%.

[0078] As examples, 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%.

[0079] In some embodiments, q1 may be 10%-23%.

[0080] When k1 and q1 are within the above ranges, the first lithium supplement agent can provide a higher lithium supplement gram capacity.

[0081] In some embodiments, k2 is 15%-70% and q2 is 8%-20%.

[0082] As examples, 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%.

[0083] In some embodiments, k2 may be 35%-50%.

[0084] 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%.

[0085] In some embodiments, q2 may be 8%-15%.

[0086] For the lithium supplement agent, as the lithium mass fraction increases, the lithium supplement gram 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 gram capacity of the lithium supplement agent decreases accordingly. When k2 and q2 are within the above range, the second lithium supplement agent can effectively alleviate the strong alkalinity of the first lithium supplement agent, so that the acidity and alkalinity of the lithium supplement additive are weakly alkaline.

[0087] The mass fraction of lithium in the first lithium supplement and the second lithium supplement can be tested by 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.

[0088] The mass fraction of carbon in the first lithium supplement and the second lithium supplement can be tested by methods known in the art. As an example, an infrared sulfur-carbon analyzer can be used for testing. Specifically, the sample to be tested is burned with oxygen in a high-temperature furnace to generate and release CO2 gas, and this method is used to separate carbon from metal elements and their compounds, and then the CO2 content is measured to convert the carbon content in the sample to be tested.

[0089] In some embodiments, 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).

[0090] 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).

[0091] 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, which can reduce the poor gelation of the positive electrode slurry and improve the processing performance of the positive electrode slurry.

[0092] In some embodiments, when the second lithium supplement agent forms a second coating layer on the surface of the first inner 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.

[0093] 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.

[0094] 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 is helpful 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, so that the pore structure originally occupied by the lithium supplement agent has larger gaps; or the pore structure originally occupied by the lithium supplement agent is completely vacant due to decomposition and gas production, thereby improving the porosity of the positive electrode sheet.

[0095] In some embodiments, d1 is 5 μm-15 μm, and / or d2 is 1 μm-5 μm.

[0096] 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.

[0097] 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.

[0098] 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 is different from that of the positive electrode active material, so when the lithium supplement additive releases lithium ions during the first charging process, the remaining part can form larger pores, further improving the porosity of the positive electrode sheet.

[0099] 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.

[0100] 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.

[0101] In some embodiments, d3 is 1 μm-10 μm, and / or d4 is 0.2 μm-1 μm.

[0102] 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.

[0103] 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.

[0104] In some embodiments, the purity of the lithium supplementing additive is greater than or equal to 90%.

[0105] As an example, the purity of the lithium supplement additive may be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%.

[0106] 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.

[0107] 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%.

[0108] In some embodiments, the initial lithium desorption 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.

[0109] 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 poorly due to excessive voltage.

[0110] 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.

[0111] In some embodiments, the first lithium supplement agent and the second lithium supplement agent may be premixed 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 subjected to a mixing treatment such as stirring.

[0112] 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 rotation speed of the ball milling process is 600rpm-1200rpm; the time of the ball milling process is 1h-4h; the grinding aid of the ball milling process includes graphite; the mass ratio of the first lithium supplement agent to the second lithium supplement agent in the mixture is (5:1)-(10:1).

[0113] The second lithium supplement agent can be coated on the surface of the first lithium supplement agent by ball milling to form a second coating layer, thereby obtaining a lithium supplement additive by coating. When the second lithium supplement agent includes a porous carbon carrier and a second core, and the second core is located in the pore structure of the porous carbon carrier, 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, and the second lithium supplement agent is fixed on the surface of the first core by ball milling, and the first core and the second core share the coating layer in the second lithium supplement agent.

[0114] In the second aspect of the present application, the present application proposes 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 supplement additive, wherein the lithium supplement additive comprises the aforementioned lithium supplement additive. Thus, the positive electrode plate has all the features and advantages of the aforementioned lithium supplement additive, which will not be described in detail here.

[0115] In some embodiments, the mass fraction of the lithium supplement additive in the positive electrode active material layer is 0.1%-10%. In some embodiments, the mass fraction of the lithium supplement additive in the positive electrode active material layer is 2%-7%.

[0116] 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%.

[0117] 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 make up for the loss of active lithium ions during the charging and discharging process of the battery, but also prevent the positive electrode active material layer from having too little positive electrode active material due to the excessive content of the lithium replenishing agent, thereby causing insufficient reversible lithium insertion vacancies in the positive electrode active material layer and causing the battery's energy density to be too low.

[0118] When the lithium-supplementing 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, resulting in larger gaps in the pore structure originally occupied by the lithium-supplementing additive; or the pore structure originally occupied by the lithium-supplementing additive is completely vacant due to decomposition and gas production, thereby improving the porosity of the positive electrode sheet. When the negative electrode sheet expands during the charging process, the pore structure in the positive electrode sheet will be squeezed, relieving the expansion stress on the negative electrode sheet, reducing the extrusion of the electrolyte inside the negative electrode sheet, and more conducive to the electrolyte reflux of the negative electrode sheet, improving the wettability of the electrolyte to the negative electrode sheet.

[0119] In some embodiments, the mass fraction of the first lithium supplement agent in the positive electrode active material layer is 0.1%-10%; the mass fraction of the second lithium supplement agent in the positive electrode active material layer is 0.1%-5%.

[0120] As an example, the mass fraction of the first lithium supplement 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%.

[0121] As an example, the mass fraction of the second lithium supplement 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%.

[0122] 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 disposed on any one or both of the two facing surfaces of the positive electrode current collector.

[0123] 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.).

[0124] 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.

[0125] 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 lithium-containing phosphates with olivine structure may include, but are not limited to, 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 doping modification and / or surface coating modification of the materials.

[0126] The battery will be accompanied by Li deintercalation and consumption during the charge and discharge process, and the molar content of Li is different when the battery is discharged to different states. In the list of positive electrode active materials in this application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li will change after the charge and discharge cycle.

[0127] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0128] In some embodiments, the positive electrode active material layer may further optionally include a binder.

[0129] 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. Thus, the bonding strength between the positive electrode active material layer and the positive electrode current collector can be improved.

[0130] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent.

[0131] 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.

[0132] In some embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the lithium supplement, the conductive agent, the 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 collector. After drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0133] In some embodiments, the positive electrode sheet can be prepared by the following method: the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, a positive electrode active material layer is formed, and then the lithium supplement agent is compounded with the positive electrode active material layer by spraying, secondary coating and other methods on the surface of the positive electrode active material layer.

[0134] In some embodiments, the solid content of the positive electrode slurry is 50%-70%.

[0135] 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%.

[0136] 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 make the positive electrode slurry have suitable fluidity, which is convenient for the coating process.

[0137] In some embodiments, the solid content of the positive electrode slurry is 60%-65%.

[0138] In the third aspect of the present application, the present application proposes a battery, comprising the aforementioned positive electrode sheet. Therefore, the battery has all the features and advantages of the aforementioned positive electrode sheet, which will not be described in detail here.

[0139] Typically, a battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charge and discharge process, active ions are embedded and removed back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuits between the positive and negative electrodes, while allowing ions to pass through.

[0140] In some embodiments, it further includes: a negative electrode plate, the negative electrode plate includes 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 includes a negative electrode active material, and the negative electrode active material includes at least one of elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0141] When the battery is charged, lithium ions will be released from the positive electrode active material, migrate to the surface of the negative electrode plate after diffusion through the electrolyte, and be embedded in the negative electrode active material; when the battery is discharged, lithium ions will be released from the negative electrode active material, migrate to the surface of the positive electrode plate after diffusion through the electrolyte, and be embedded in the positive electrode active material. The volume of the negative electrode active material will expand due to the embedding of lithium ions during the charging and discharging process, and the volume will shrink due to the release of lithium ions. As a result, the volume of the negative electrode active material will continue to change during the battery's charge and discharge cycle. Usually, the volume change of the negative electrode active material with a higher gram capacity is greater during the charging and discharging process. Taking the negative electrode active material with a larger volume expansion during the charging and discharging cycle, such as silicon-based negative electrode active material, as an example, the negative electrode plate containing silicon-based negative electrode material has a huge volume effect during the charging and discharging cycle, resulting in the electrolyte inside the negative electrode plate being gradually squeezed out along one side of the negative electrode plate, thereby reducing the wettability of the electrolyte to part of the negative electrode plate, and finally causing lithium precipitation, which significantly affects the cycle life and capacity of the battery cell.

[0142] 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, so that the pore structure originally occupied by the lithium-replenishing additive appears with larger gaps; or the pore structure originally occupied by the lithium-replenishing additive is completely vacant due to decomposition and gas production, 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.

[0143] 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 disposed on any one or both of the two facing surfaces of the negative electrode current collector.

[0144] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, as the metal foil, a copper foil may be used. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0145] In some embodiments, the negative electrode active material layer may further include a binder. The binder includes 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).

[0146] 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.

[0147] 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)).

[0148] In some embodiments, the negative electrode sheet can be prepared in the following manner: 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 collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0149] [Electrolytes]

[0150] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. The present application has no specific restrictions on the type of electrolyte, which can be selected according to needs. For example, the electrolyte can be liquid, gel or all-solid.

[0151] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0152] 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 dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0153] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl 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.

[0154] In some embodiments, the electrolyte may further include additives, such as 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, additives that improve battery high or low temperature performance, etc.

[0155] [Isolation film]

[0156] 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 stability and mechanical stability can be selected.

[0157] In some embodiments, the material of the isolation membrane includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0158] 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.

[0159] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.

[0160] In some embodiments, the battery may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0161] In some embodiments, the outer packaging of the battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0162] The present application has no particular limitation on the shape of the battery, which may be cylindrical, square or any other shape. Figure 1 The battery cell 5 is a square structure as an example.

[0163] In some embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a top cover assembly 53. Among them, 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 form 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.

[0164] 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 according to the application and capacity of the battery module.

[0165] Figure 3 4 is an example of a battery module. Figure 3In the battery module 4, the plurality of battery cells may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells may be fixed by fasteners.

[0166] Optionally, the battery module 4 may further include a housing having a receiving space, and a plurality of battery cells are received in the receiving space.

[0167] 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 according to the application and capacity of the battery pack.

[0168] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0169] In a fourth aspect of the present application, the present application proposes an electrical device, comprising the aforementioned battery. Therefore, the electrical device has all the features and advantages of the aforementioned battery, which will not be described in detail here.

[0170] Batteries, battery modules, and battery packs can be used as power sources for electrical devices or as energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0171] As an electrical device, a battery, a battery module or a battery pack can be selected according to its usage requirements.

[0172] Figure 6 The power consumption device is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the power consumption device for the battery, a battery pack or a battery module can be used.

[0173] As another example, the device may be a mobile phone, a tablet computer, a notebook computer, etc. The device is usually required to be light and thin, and a battery may be used as a power source.

[0174] The scheme of the present application is described below by specific examples. It should be noted that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If no specific technology or conditions are specified in the examples, the technology or conditions described in the literature in this area or the product instructions are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0175] Example 1

[0176] Preparation of positive electrode:

[0177] The positive electrode active material LiFePO4 (LFP), the conductive agent acetylene black, the binder PVDF, and the lithium supplement additive are mixed in a weight ratio of 95:1:2:2 in an N-methylpyrrolidone solvent (NMP) system to obtain a positive electrode slurry with a solid content of 60%. The positive electrode slurry is coated on an 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 .

[0178] 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.

[0179] The synthesis method of the first lithium supplement is as follows:

[0180] Fe2O3 and Li2O are solid-phase mixed at a molar ratio of Li:Fe of 5.12:1, heated to 300°C in an argon atmosphere, and maintained for 6 hours to obtain a first core lithium ferrite, and then a nano-alumina coating agent is added, wherein the mass ratio of alumina to lithium ferrite is 1:100, and a high-speed mixer is used to mix evenly, and then maintained at 900°C for 8 hours to obtain lithium ferrite with a surface coated with alumina. Then, the lithium ferrite with a surface coated with alumina obtained above is crushed, and after crushing, dopamine (DA, C8HNO2) is mixed with lithium ferrite at a mass ratio of 1:28, so that dopamine is polymerized on the surface of lithium ferrite to form a polydopamine (PDA) nanofilm, and then the PDA-coated material is maintained at 900°C in an argon atmosphere for 8 hours to obtain a first lithium supplement, wherein the first core of the first lithium supplement is lithium ferrite, the first sub-coating layer is Al2O3, and the second sub-coating layer is a carbon material.

[0181] The synthesis method of the second lithium supplement is as follows:

[0182] 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 65 g / L was stirred for reaction for 2 hours to obtain a second inner core, and the second inner core was mixed with a carbon nanotube solution with a mass fraction of 1 wt%, and the mass ratio of the second inner core to the carbon nanotube was 6:1. After ultrasonication for 30 minutes, the solution was maintained at 150° C. in an oven for 8 hours for evaporation and crystallization to obtain a second lithium supplement.

[0183] Preparation of negative electrode sheet:

[0184] 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 to obtain a negative electrode slurry, which was then 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 is 15 g / cm 2 .

[0185] Battery assembly:

[0186] A PE / PP porous polymer film with a thickness of 12 μm was used as the isolation membrane.

[0187] 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.

[0188] The positive electrode sheet, the separator, and the negative electrode sheet are stacked in order, the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then wound to obtain a bare cell. The bare cell is placed in an outer package, injected with a prepared electrolyte and packaged to obtain a battery.

[0189] 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.

[0190] In Example 2, the amount of dopamine added was adjusted so that the mass ratio of dopamine to lithium ferrite was 1:15.

[0191] The synthesis method of the second lithium supplement in Example 3 is as follows: take ketomalonic acid (HO)2C(COOH)2, extract it with 100% ethanol, react ketomalonic acid with LiOH in a mass ratio of 1:2.1, centrifuge the product and wash it with ethanol 3 times to remove excess alkali, then obtain the second inner core Li2C3O5 by vacuum dehydration at 165°C, mix the second inner core with a carbon nanotube solution with a mass fraction of 1wt%, and the mass ratio of the second inner core to the carbon nanotube is 6:1. After ultrasonication for 30 minutes, evaporate and crystallize at 150°C in an oven for 8 hours to obtain the second lithium supplement.

[0192] 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, the ball milling speed is 1000 rpm, the time is 3 hours, and the grinding aid is graphite.

[0193] In Examples 5-9, the masses of the lithium supplement additive and the positive electrode active material in the positive electrode slurry are adjusted accordingly, the sum of the mass fraction of the lithium supplement additive and the mass fraction of the positive electrode active material is 97%, and the mass fraction of the conductive agent and the mass fraction of the binder remain unchanged, which is the same as Example 1.

[0194] The difference between Example 10 and Example 1 is that the first core is Li2C2O4.

[0195] The difference between Example 11 and Example 1 is that the first core is Li2NiO2.

[0196] The lithium supplement additive in Comparative Example 1 only uses the first lithium supplement agent.

[0197] The lithium supplement additive in Comparative Example 2 only uses the second lithium supplement agent.

[0198] Table 1

[0199]

[0200]

[0201] Table 2

[0202]

[0203] 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.

[0204] 1. Charge and discharge specific 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 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) = first cycle charge capacity / mass of positive electrode active material.

[0205] 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.

[0206] The above-mentioned charge specific capacity and discharge specific capacity tests were repeated 5 times and the average values ​​were taken.

[0207] 2. Calculation of battery volume energy density:

[0208] The internal dimensions of the battery shell are measured as length a, width b, and height c. Each battery is charged at 25°C at a rate of 1C to a voltage of 3.65V, and then discharged at a rate of 1C to a voltage of 2.5V, and the discharge energy S0 is measured.

[0209] Battery volume energy density = S0 / (a×b×c)

[0210] 3. Stability of cathode slurry:

[0211] The positive electrode slurry prepared above was placed in a beaker and sealed with plastic wrap. After standing for 24 hours, the following observations were made:

[0212] (1) Take out the positive electrode slurry that has been left to stand and record the marking on the front of the beaker and the sealing condition of the beaker.

[0213] (2) Open the plastic wrap and use a steel ruler to gently move the surface of the positive electrode slurry to check whether there is any abnormality on the surface of the positive electrode slurry or whether the color has changed.

[0214] (3) Slowly insert a steel ruler into the slurry and gently move it up and down to preliminarily determine the viscosity of the positive electrode slurry.

[0215] (4) Use a steel ruler to scoop out part of the slurry, check the fluidity of the positive electrode slurry, and take photos for record.

[0216] The gel state of the positive electrode slurry is divided into the following levels:

[0217] 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.

[0218] 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.

[0219] 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.

[0220] d. No gel: The slurry has good fluidity and has no other abnormalities mentioned above.

[0221] Table 3

[0222]

[0223]

[0224] It can be seen from Table 2 that the lithium-supplementing additive in Comparative Example 1 only uses the first lithium-supplementing agent with strong alkalinity, which leads to serious gelation of the positive electrode slurry, loss of fluidity of the slurry, unstable quality of 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 charging and discharging, so that the first cycle charging capacity of the battery is low, and the volume energy density of the battery is low. 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 charging and discharging, and improve the first cycle charging 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, and the lithium-supplementing additive can hardly provide discharge capacity, the first cycle discharge capacity and volume energy density of the battery are low.

[0225] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium supplement additive, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: k1 is 0%-30%, and q1 is 7%-70%.

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

9. The lithium supplement additive according to claim 1, characterized in that: 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 claim 1, characterized in that: The second core includes at least one of Li2C3O5, Li2C4O4, and Li2C4O6.

11. The lithium supplement additive according to claim 1, characterized in that: 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, characterized in that: The invention comprises 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 supplement additive, and the lithium supplement additive comprises the lithium supplement additive according to any one of claims 1 to 11.

13. The positive electrode sheet according to claim 12, characterized in that: 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, characterized in that: 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, characterized in that: Comprising the positive electrode sheet as described in any one of claims 12 to 14.

16. An electrical device, characterized in that: Comprising the battery of claim 15.

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