Positive pole piece, preparation method of positive pole piece, battery and electric equipment

Abstract

The invention discloses a positive pole piece, a preparation method of the positive pole piece, a battery and electric equipment. The positive pole piece comprises a base layer and an active layer; the active layer is located on the base layer and comprises a positive electrode active material and a lithium supplementing agent, and a product obtained after lithium supplementing of the lithium supplementing agent can be dissolved in the electrolyte. Through the mode, irreversible lithium ion loss in a battery system can be supplemented, the energy utilization rate of the battery is improved, and the cycle life of the battery is prolonged; meanwhile, the porosity of the positive pole piece is improved, and the rate capability of the positive pole piece is improved.

Description

Technical Field

[0001] The present application relates to the field of new energy technology, and in particular to a positive electrode sheet, a method for preparing a positive electrode sheet, a battery, and an electrical device. Background Art

[0002] Lithium-ion batteries have a high energy density and are widely used in wireless communications, transportation, aerospace, and other fields. During the charge and discharge process of lithium-ion batteries, the formation of a solid electrolyte interphase (SEI) film and certain side reactions can lead to irreversible loss of lithium ions, reducing the energy utilization rate and cycle life of the lithium-ion battery. The above statements are intended only to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention

[0003] The main technical problem solved by the present application is to provide a positive electrode sheet, a method for preparing the positive electrode sheet, a battery and an electrical device, which can improve the energy utilization rate of lithium-ion batteries and extend the cycle life.

[0004] In order to solve the above technical problems, a technical solution adopted in this application is: to provide a positive electrode plate, the positive electrode plate includes a base layer and an active layer; the active layer is located on the base layer, the active layer includes a positive electrode active material and a lithium supplement, the lithium supplement includes Wherein, R1, R2, and R3 contain -C=N-OLi or at least one double bond, aromatic group, or amino group that forms a conjugated structure with -C=N-OLi.

[0005] The above-mentioned positive electrode lithium supplement can release lithium ions (Li + ), achieving the effect of lithium replenishment; at the same time, the product after lithium replenishment dissolves into the electrolyte system, achieving the effect of "self-dissolution" lithium replenishment, which is beneficial to improving the energy utilization rate of lithium-ion batteries and extending the cycle life of lithium-ion batteries.

[0006] In one embodiment, R1, R2, and R3 include an alkyl group with 2-15 carbon atoms or a polymer group with a number average molecular weight Mn ≤ 15W. Through this configuration, the lithium supplement product of the lithium supplement agent with an alkyl group or polymer group can dissolve in the electrolyte system after lithium supplementation, which helps reduce the residual lithium supplement product and achieve a "self-dissolving" lithium supplement effect.

[0007] In one embodiment, any one of R1, R2, and R3 contains at least one -C=N-OLi. In this case, the lithium replenisher can store more lithium ions, which is beneficial to improving the ability of the positive electrode material to store and release lithium ions, improving the lithium replenishment effect, and helping to increase the energy density of the lithium-ion battery.

[0008] In one embodiment, the lithium replenisher includes one or more of diaminoglyoxime lithium salt, m-benzyldioxime lithium salt, p-phenylenediamine oxime lithium salt, benzildioxime lithium salt, 1,4-benzoquinonedioxime lithium salt, 2,4-butanedioxime lithium salt, methylglyoxime lithium salt, and polyacrylamidoxime lithium salt. Using one or more of these compounds as a lithium replenisher can replenish the irreversible lithium loss generated during the charge and discharge process of a lithium-ion battery, thereby improving the energy utilization rate and cycle life of the lithium-ion battery. Furthermore, the lithium replenisher can reduce residual products after lithium replenishment without generating gas, thus reducing the occurrence of side reactions and achieving a self-degrading lithium replenishment effect.

[0009] In one embodiment, the weight ratio of the lithium replenisher to the active layer is 1.0% to 12.0%. Within this weight ratio range, the lithium replenisher can ensure the lithium replenishment effect of the lithium replenisher, increase the porosity of the positive electrode sheet, and enhance the rate performance of the electrode sheet; at the same time, the risk of electrode collapse caused by excessive porosity of the positive electrode sheet is reduced, and the stability of the positive electrode sheet is maintained.

[0010] In one embodiment, the amount of lithium supplement agent added is M = 1 / Cb [(1-CEa)Ma×Ca+(CEc-CEa)Mc×Cc], where Cb is the charge capacity of the lithium supplement agent, CEa is the first effect of the anode on the lithium half-cell, Ma is the mass of the anode, Ca is the discharge capacity of the anode on lithium, CEc is the first effect of the cathode on the lithium half-cell, Mc is the mass of the cathode, and Cc is the discharge capacity of the cathode on lithium. This configuration allows for a relatively accurate determination of the required amount of lithium supplement agent for different battery systems. Furthermore, based on the weight ratio of the lithium supplement agent in the active layer, the mass of the active layer in the positive electrode material can be determined, facilitating the design of the physical parameters of the positive electrode sheet.

[0011] In one embodiment, the particle size Dv50 of the lithium supplement agent is 0.5-3.0 μm. A particle size within this range ensures that the pore size formed after the lithium supplement agent is digested is suitable for ion transport, thereby improving the battery's rate performance. It also reduces damage to the positive electrode sheet structure caused by excessively large particle size, including cracks or collapse, thereby reducing the impact of positive electrode sheet structural damage on battery performance.

[0012] In one embodiment, the infrared detection results of the positive electrode include 1665cm -1 (C=N), 945cm -1 (NO) and 1500cm -1 The infrared characteristic peak of (N=O) bond. At this time, it indicates that lithium supplement is added to the positive electrode plate, and the lithium supplement includes

[0013] In one embodiment, the thickness of the active layer on either side of the positive electrode plate is 120-450 μm. Because the lithium supplement increases the porosity of the positive electrode plate, the thickness of the plate can be appropriately increased. By increasing the thickness of the active layer, the content of active material can be increased, thereby improving the energy density of the battery. Furthermore, the presence of the plate porosity effectively increases the migration rate of active ions in the electrode material, reducing the polarization internal resistance and improving the rate performance of the plate.

[0014] In one embodiment, the positive electrode active material includes lithium manganese iron phosphate (LiFe x Mn 1-x PO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), high nickel layered material Li 1+y (Ni a Co b Mn 1-a-b- c B c ) 1-y O2; where 0.05≤y≤0.05, 0.85≤a≤0.95, 0.01≤b≤0.10, 0≤c≤0.05, and B is Zn 2+ , Mg 2 + , Al 3+ , Cr 3+ , Sc 3+ , Ga 3+ , La 3+ , Sm 3+ , Ti 4+ , Zr 4+ , Nb 5+ , W 6+ When the above-mentioned positive electrode active materials are applied to the positive electrode sheet, the positive electrode sheet needs to be replenished with lithium. By adding a lithium replenisher, the rate performance of the positive electrode sheet can be improved, the energy utilization rate of the battery can be increased, and the cycle life of the battery can be extended.

[0015] In one embodiment, the active layer further includes a conductive agent and a binder. The conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black, and acetylene black, and the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane. The conductive agent imparts electrical conductivity to the electrode, while the binder improves the adhesion stability of the active layer and reduces the likelihood of powder shedding.

[0016] In order to solve the above technical problems, another technical solution adopted in this application is: providing a method for preparing a positive electrode sheet, comprising mixing a positive electrode active material and a lithium supplement agent with a solvent to obtain a positive electrode slurry; coating the positive electrode slurry on a substrate, and drying to obtain a positive electrode sheet; wherein the lithium supplement agent comprises R1, R2, and R3 may contain -C=N-OLi or at least one double bond, aromatic group, or amino group that forms a conjugated structure with -C=N-OLi. The aforementioned positive electrode lithium replenisher can release lithium ions during battery use, achieving a lithium replenishment effect. Simultaneously, the post-replenishment lithium product dissolves into the electrolyte system, achieving a "self-dissolving" lithium replenishment effect, which is beneficial for improving the energy utilization of lithium-ion batteries and extending their cycle life.

[0017] In one embodiment, a precursor oxime is mixed with a lithium source and reacted to obtain a lithium supplement. The precursor oxime comprises Among them, R1, R2, and R3 may contain -C=N-OH or at least one double bond, aromatic group, or amino group that forms a conjugated structure with -C=N-OH. By the above method, a lithium supplement can be prepared. The lithium supplement agent can release lithium ions under the formation voltage to achieve the lithium supplement effect.

[0018] In one embodiment, the lithium source includes one or more of lithium ethoxide, lithium methoxide, lithium hydride, lithium nitride, and n-butyl lithium. These compounds are soluble in the solvent used in the reaction system and can fully react with the precursor oxime.

[0019] In one embodiment, the solvent used in the reaction system after the precursor oxime and the lithium source are mixed is an aprotic solvent. Optionally, the aprotic solvent includes one or more of an ether solvent, benzene, and tetrahydrofuran. These solvents do not affect the reaction between the precursor oxime and the lithium source, and do not react with the lithium source or the precursor oxime, thereby facilitating the smooth preparation of the lithium supplement.

[0020] To solve the above technical problems, another technical solution adopted by this application is to provide a battery, comprising any of the above-mentioned positive electrode sheets, or a positive electrode sheet prepared using any of the above-mentioned methods for preparing a positive electrode sheet. During use, the lithium replenisher in the positive electrode sheet releases lithium ions, replenishing the lithium ions consumed in forming the SEI film and the lithium ions consumed by side reactions within the battery, thereby improving the battery's energy utilization and extending the battery's cycle life. At the same time, the lithium replenishment product can dissolve into the electrolyte system, forming pores in the active layer of the positive electrode sheet, that is, the battery includes a porous positive electrode sheet, which improves the rate performance of the positive electrode sheet.

[0021] In one embodiment, the porosity of the positive electrode sheet after the formation reaction is 20% to 35%. After the formation reaction, the positive electrode sheet has a larger porosity, which can improve the electrolyte infiltration effect.

[0022] To solve the above technical problems, another technical solution adopted by the present application is to provide an electric device comprising the above battery. The electric device has at least the same advantages as the battery and can improve the battery life of the electric device.

[0023] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] Figure 1 is a schematic structural diagram of a positive electrode sheet according to one or more embodiments;

[0026] Figure 2 is a schematic diagram of the state change of the positive electrode sheet according to one or more embodiments;

[0027] Figure 3 is a schematic diagram of an exploded structure of a battery according to one or more embodiments;

[0028] Figure 4 is a schematic diagram of an exploded structure of a battery cell according to one or more embodiments;

[0029] Figure 5 is a schematic structural diagram of a vehicle according to one or more embodiments.

[0030] In the attached figure:

[0031] 1000, vehicle; 300, motor; 200, controller; 100, battery; 10, housing; 11, first part; 12, second part; 20, battery cell; 21, end cap; 21a, electrode terminal; 22, housing; 23, electrode assembly; 30, positive electrode sheet; 31, base layer; 32, active layer; 321, lithium supplement; 322, pores; 40, porous positive electrode sheet. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and effect of this application clearer and more specific, the following embodiments of the technical solution of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application and are therefore only examples and are not intended to limit the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0034] In the description of the embodiments of the present application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood as indicating or implying relative importance or implicitly indicating the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), similarly, "multiple groups" refers to more than two (including two), and "multiple pieces" refers to more than two (including two), unless otherwise clearly and specifically defined.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0037] Amounts, ratios, and other numerical values are presented herein in a range format. It should be understood that such range format is used for convenience and brevity and should be interpreted flexibly to include not only the values explicitly specified as range limits, but also all individual values or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0038] If not otherwise specified, all steps of the present application may be performed sequentially, randomly, or in parallel, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially, or may include steps (a) and (b) performed simultaneously in parallel. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0039] Lithium-ion batteries, as a new type of green secondary battery, are widely used in electric vehicles, energy storage systems, and renewable energy. With the rapid development of lithium-ion batteries in my country, they are bound to achieve multiple improvements. From a technical perspective, "high safety," "high efficiency," "long life," and "low cost" will be the core solutions and goals for the development of power battery technology.

[0040] During the formation process of lithium-ion batteries, the formation of the solid electrolyte interphase (SEI) film consumes some lithium ions, increasing the irreversible capacity during the initial charge and discharge cycle and reducing the charge and discharge efficiency of the electrode material. Furthermore, the charge and discharge process of lithium-ion batteries also involves side reactions, such as the consumption of active lithium ions caused by side reactions at the negative electrode, which manifests as the continued thickening and increased expansion force of the SEI film. Consequently, the lithium ions in the positive electrode material undergo irreversible loss, resulting in a loss of active lithium ions in the positive electrode material. This further reduces the energy utilization rate of lithium-ion batteries and shortens their cycle life.

[0041] To reduce the negative impact of irreversible lithium ion loss on lithium-ion batteries, the negative and positive electrodes of lithium-ion batteries can be pre-lithiated. Pre-lithiation, also known as pre-lithiation or lithium replenishment, refers to the process of adding a small amount of lithium source to the electrode material before the battery is operational. This is to compensate for the lithium source consumed during the battery's charge and discharge process, thereby increasing the battery's capacity and energy density.

[0042] At present, conventional lithium replenishers used in pre-lithiation are mainly divided into positive electrode lithium replenishers and negative electrode lithium replenishers. Among them, positive electrode lithium replenishers mainly utilize the low initial efficiency of positive electrode lithium replenishers. During the charging process, lithium ions are replenished to the anode to form SEI film and replenish irreversible lithium ion loss. They can be divided into inorganic lithium replenishers and organic lithium replenishers.

[0043] Inorganic lithium supplements, including LiCoO2, Li3N, Li2S / Co, LiF / Co, Li2O, LiNiO2, and Li5FeO4, often suffer from delithiation residues and gassing in batteries. Organic lithium supplements, primarily conjugated quinones and ketones, are characterized by their ability to leave no oxidative residue and contain low levels of inactive substances. They are primarily used as cathode materials for lithium-ion batteries, complementing lithium metal anodes, but their use as lithium supplements is less studied.

[0044] Based on the above considerations, in order to solve the problems of reduced battery energy utilization and shortened cycle life of lithium-ion batteries due to irreversible lithium ion loss, and at the same time reduce delithiation residue, the present application proposes a positive electrode plate, which includes an active layer, and the active layer includes a lithium replenisher. The lithium replenisher can release lithium ions to achieve a lithium replenishment effect. At the same time, the product after lithium replenishment is dissolved into the electrolyte system, and there is no obvious residue in the positive electrode plate.

[0045] According to some embodiments of the present application, the present application discloses a positive electrode sheet, which includes a base layer and an active layer, wherein the active layer is located on the base layer, and the active layer includes a positive electrode active material and a lithium supplement. The lithium supplement includes Among them, R1, R2, and R3 may contain -C=N-OLi or at least one double bond, aromatic group, or amino structure that forms a conjugated structure with -C=N-OLi.

[0046] Among them, the base layer is a conductive base layer, which can be used as a current collector and can be made of metal foil or composite materials. For example, it can be a composite conductive material formed by mixing a metal material with a polymer substrate. For example, aluminum foil can be used as the metal foil. The composite conductive material may include a polymer base layer and a metal layer formed on at least one surface of the polymer base layer. The composite conductive material can be formed by forming a metal material (aluminum, aluminum 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.). The base layer can be in the shape of a cube, having a first surface and a second surface arranged opposite to each other along its thickness direction, so as to support the arrangement of other layer structures.

[0047] The active layer comprises at least the positive electrode active material. The active layer can be a layered structure primarily composed of the active material, specifically a thin film. The active layer can be provided only on the first or second surface of the substrate, or on both surfaces. The active layer can be provided directly on the substrate, or a layer of other functional materials can be provided between the active layer and the substrate. The active layer is the primary structural layer of the electrode, fulfilling the basic battery functions.

[0048] In this embodiment, the active layer also includes a lithium supplement agent, which is Furthermore, any one of R1, R2, and R3 contains an unsaturated bond that forms a conjugated structure with -C=N-OLi, thus the lithium supplement is a conjugated oxime lithium salt. The conjugated structure and the NO structure act synergistically, giving the conjugated oxime lithium salt a strong electron-donating effect. During the formation process of the lithium-ion battery, a redox reaction can occur, removing lithium ions and converting to a nitroso structure. The reaction formula is as follows: At the same time, the nitroso structure is easily soluble in the electrolyte, so that the lithium replenishment product of the lithium replenisher dissolves into the electrolyte system, leaving no obvious residue on the positive electrode plate, and after dissolution, it no longer participates in the lithium replenishment process.

[0049] R1, R2, and R3 include any one of hydrogen, amino, alkyl, aryl, or polymer groups.

[0050] Therefore, the lithium replenisher can replenish the irreversible lithium loss generated during the charge and discharge process of the lithium-ion battery, including the lithium ions consumed in the formation of the SEI film during the formation process and the lithium ions consumed in the side reactions, thereby improving the energy utilization rate and cycle life of the lithium-ion battery; at the same time, the lithium replenisher can reduce the residual product after lithium replenishment, and at the same time does not produce gas, reducing the occurrence of side reactions, and achieving a self-degrading lithium replenishment effect.

[0051] See also Figure 1 and Figure 2 , Figure 1 is a schematic structural diagram of a positive electrode sheet according to one or more embodiments, Figure 2 Figure 1 shows the state changes of a positive electrode according to one or more embodiments. The lithium replenisher's post-replenishment products dissolve into the electrolyte system, creating pores in the active layer of the positive electrode. This increases the porosity of the positive electrode, thereby increasing the migration rate of active ions and improving the rate capability of the positive electrode. Furthermore, the electrolyte fills the spaces previously occupied by the lithium replenisher, significantly increasing the contact area between the active material and the electrolyte and improving electrolyte wetting.

[0052] In one embodiment, R1, R2, and R3 are alkyl groups with 2 to 15 carbon atoms or polymer groups with a number average molecular weight Mn≤15W.

[0053] When the number of carbon atoms in the alkyl group is within the range of 2-15, it first meets the minimum requirement for an unsaturated bond to form a conjugated structure with -C=N-OLi. Furthermore, when the number of carbon atoms exceeds 15, the solubility of the alkyl compound decreases rapidly, resulting in a reduced solubility of the lithium supplement product in the electrolyte system.

[0054] Polymers are homologous mixtures of identical chemical compositions but varying degrees of polymerization—that is, mixtures of polymers with varying chain lengths. Molecular size is typically characterized by the average molecular weight (Mn), which is the statistical average of the number of molecules. The higher the Mn, the lower the solubility of the polymer. When the Mn exceeds 15W, the polymer's molecular structure becomes more complex and bulkier, leading to stronger intermolecular interactions and reduced solubility.

[0055] Therefore, when R1, R2, and R3 are alkyl groups with carbon atoms of 2-15 or polymer groups with a number average molecular weight Mn≤15W, it is beneficial for lithium supplementation. The post-lithium replenishment products dissolve in the electrolyte system, which helps reduce the residual post-lithium replenishment products, achieve a self-digesting lithium replenishment effect, and reduce the impact of lithium replenishment agent residues on battery performance. The alkyl chain or polymer chain may have a functional group that does not contain active hydrogen.

[0056] In one embodiment, any one of R1, R2, and R3 contains at least one -C=N-OLi. The presence of two or more oxime lithium salt structures increases the lithium ion density in the lithium supplement agent molecule. The lithium ion density of a lithium supplement agent is the number of lithium ions contained in a unit molar mass of the lithium supplement agent. The calculation formula is: lithium ion density of lithium supplement agent = number of lithium ions in a single lithium supplement agent molecule / relative molecular mass of the lithium supplement agent.

[0057] At this time, the lithium supplement can store more lithium ions, which is beneficial to improving the ability of the positive electrode material to store and release lithium ions, improving the lithium supplement effect, and helping to increase the energy density of the lithium-ion battery; at the same time, lithium supplements with high lithium ion density can store more energy with the same amount of substance, which is beneficial to the lightweighting and miniaturization of batteries and electrical equipment.

[0058] In one embodiment, the lithium supplement includes one or more of diaminoglyoxime lithium salt (Formula 1), m-benzyldioxime lithium salt (Formula 2), p-phenylenediamide oxime lithium salt (Formula 3), benzildioxime lithium salt (Formula 4), 1,4-benzoquinonedioxime lithium salt (Formula 5), 2,4-butanedioxime lithium salt (Formula 6), methylglyoxime lithium salt (Formula 7), and polyacrylamidoxime lithium salt (Formula 8). The types of lithium supplements are not limited to the above.

[0059]

[0060]

[0061] By using one or more of the above compounds as lithium replenishers, the irreversible lithium loss generated during the charging and discharging process of the lithium-ion battery can be replenished, including the lithium ions consumed in the formation of the SEI film during the formation process and the lithium ions consumed in side reactions, thereby improving the energy utilization rate and cycle life of the lithium-ion battery; at the same time, it can reduce the residual product after lithium replenishment while not generating gas, reducing the occurrence of side reactions, and achieving a self-degrading lithium replenishment effect.

[0062] In one embodiment, the weight ratio of the lithium supplement agent to the active layer is 1.0%-12.0%. When the lithium supplement agent is added within this range, on the one hand, the lithium supplement effect of the lithium supplement agent can be guaranteed. On the other hand, the lithium supplement agent self-decomposes after lithium supplementation to form pores on the positive electrode plate, which can increase the porosity of the plate, thereby increasing the migration rate of active ions and improving the rate performance of the positive electrode plate. In addition, when the weight ratio of the lithium supplement agent to the active layer exceeds 12.0%, the pores formed are too many and too large, increasing the risk of collapse of the positive electrode plate, thereby inducing side reactions of the positive electrode material, such as dissolution of transition metal ions, which reduces the thermal stability, structural stability and cycle stability of the positive electrode material.

[0063] In some embodiments, the weight proportion of the lithium supplement may be 2.0%, 4.0%, 8.0%, 12.0%, 0.5%, or 15.0%.

[0064] The amount of lithium supplement to be added is calculated specifically for different lithium-ion battery systems. In one embodiment, the amount of lithium supplement to be added is M = 1 / Cb [(1-CEa)Ma×Ca+(CEc-CEa)Mc×Cc], where Cb is the charge capacity of the lithium supplement, CEa is the first effect of the anode on the lithium half-cell, Ma is the mass of the anode, Ca is the discharge capacity of the anode on lithium, CEc is the first effect of the cathode on the lithium half-cell, Mc is the mass of the cathode, and Cc is the discharge capacity of the cathode on lithium.

[0065] A lithium-ion half-cell refers to a lithium battery that uses lithium, which has the lowest standard reduction potential, as the negative electrode, and lithium-ion battery cathode and anode materials as the positive electrode, respectively. When the cathode material of a lithium-ion battery is used as the positive electrode, it is called a cathode-to-lithium half-cell; when the negative material of a lithium-ion battery is used as the positive electrode, it is called an anode-to-lithium half-cell. After the cathode-to-lithium half-cell is completed, it first undergoes a charge-discharge cycle: During charging, lithium ions are deintercalated from the positive electrode and deposited on the lithium metal sheet at the negative electrode. During discharge, the lithium metal sheet loses electrons, forming lithium ions that travel through the electrolyte and then reintercalate into the positive electrode. However, not all of the lithium ions deintercalated from the positive electrode during charging return to the positive electrode during discharge. The discharge capacity is expressed as the battery's output capacity measured under specified conditions. The initial discharge capacity divided by the initial charge capacity is the initial efficiency, or first efficiency, of this half-cell.

[0066] The amount of lithium supplement added depends on two aspects of the lithium-ion battery. The first is the amount of lithium ions consumed when the battery is first charged to form the SEI film, which is borne by the "(1-CEa)Ma*Ca" part in the above formula, that is, when the negative electrode material half-cell is discharged for the first time, the lithium ions will first form a SEI film on the surface of the negative electrode before being embedded in the negative electrode, thereby forming irreversible lithium ion loss; the second is the amount of lithium ions consumed when the lithium ions deintercalated from the positive electrode during battery charging do not all return to the positive electrode during discharge, which is reflected by the "(CEc-CEa)Mc*Cc" part in the above formula. For the positive electrode material half-cell, the structure of the positive electrode material will change due to delithiation after discharge, thereby reducing the positions that can be embedded in lithium in the material, thereby forming irreversible lithium ion loss.

[0067] The above setup allows for a relatively accurate determination of the required lithium supplement dosage for different battery systems. Furthermore, the mass of the active layer in the positive electrode material can be determined based on the weight ratio of the lithium supplement in the active layer. This facilitates the design of the physical parameters of the positive electrode sheet and facilitates its fabrication.

[0068] In the above embodiment, the product of the lithium replenisher after lithium replenishment dissolves in the electrolyte system, forming pores on the positive electrode plate. In terms of pore structure, the amount of lithium replenisher added affects the porosity of the positive electrode plate, and the particle size of the lithium replenisher affects the size of the pores in the positive electrode plate.

[0069] In one embodiment, the particle size Dv50 of the lithium supplement is 0.5-3.0 μm. Dv50 is a parameter used to describe particle size distribution, which indicates the particle size range below which 50% of the particle mass or volume fraction in the particle distribution falls.

[0070] The particle size of the lithium supplement agent is within the above range, which can ensure that the pore size formed after the lithium supplement agent is digested is suitable for ion transmission, which is beneficial to increase the ion transmission channel of the positive electrode plate and improve the battery's rate performance. It can also reduce the damage to the positive electrode plate structure caused by excessive particle size, including cracks or collapse, thereby reducing the impact of positive electrode plate structure damage on battery performance.

[0071] In some embodiments, the particle size Dv50 of the lithium supplement may be 0.2, 1.0, or 6.0 μm.

[0072] Since the lithium supplement increases the porosity of the positive electrode sheet, the thickness of the positive electrode sheet can be adjusted accordingly. In one embodiment, the thickness of the active layer on either side of the positive electrode sheet is 120-450 μm.

[0073] In this embodiment, increasing the thickness of the active layer increases the active material content, thereby improving the battery's energy density. Simultaneously, the self-dissolving lithium supplement enhances the electrode porosity, increases the electrolyte diffusion path, and improves the electrolyte wettability of the electrode. This effectively increases the migration rate of active ions in the electrode material, reduces polarization internal resistance, and enhances the electrode's rate capability. Furthermore, the dissolved lithium supplement product produces virtually no side effects and has no negative impact on the battery.

[0074] When the positive electrode plate includes the above-mentioned lithium supplement, there are characteristic functional groups in the chemical composition. In one embodiment, the infrared detection results of the positive electrode plate include 1665cm -1 (C=N), 945cm -1 (NO) and 1500cm -1 The infrared characteristic peak of (N=O) bond.

[0075] Of which 1665cm -1 (C=N) and 945cm -1 The infrared characteristic peak of the (NO) bond corresponds to the lithium supplement Characteristic functional groups, 1500 cm -1 The infrared characteristic peak of the (N=O) bond corresponds to the characteristic functional group of the nitroso compound produced after the lithium supplement is added. At this time, it indicates that the lithium supplement is added to the positive electrode.

[0076] In addition, since the lithium supplement agent dissolves in the electrolyte system after playing the role of lithium supplement in the battery system, the 1500cm -1 The infrared characteristic peak of (N=O) bond.

[0077] The present application provides a method for preparing a positive electrode sheet, comprising the following steps: mixing a positive electrode active material and a lithium supplement agent with a solvent to obtain a positive electrode slurry; coating the positive electrode slurry on a substrate, and drying the substrate to obtain a positive electrode sheet; wherein the lithium supplement agent comprises Among them, R1, R2, and R3 may contain -C=N-OLi or at least one double bond, aromatic group, or amino structure that forms a conjugated structure with -C=N-OLi.

[0078] In one embodiment, the lithium supplement agent is prepared by the following method: a precursor oxime is mixed with a lithium source and reacted to obtain a lithium supplement agent, wherein the precursor oxime comprises Among them, R1, R2, and R3 may contain -C=N-OH or at least one double bond, aromatic group, or amino structure that forms a conjugated structure with -C=N-OH.

[0079] The precursor oxime must contain a =N-OH functional group. Only precursors containing a =N-OH functional group can react with a lithium source to produce a lithium supplement. The lithium source refers to a material or substance that provides lithium ions. During the preparation of the lithium supplement, lithium ions are provided to replace the hydrogen atoms in the precursor oxime =N-OH functional group. The lithium supplement can be prepared by the above method. The lithium supplement agent can release lithium ions under the formation voltage to achieve the lithium supplement effect.

[0080] In one embodiment, the lithium source includes one or more of lithium ethoxide, lithium methoxide, lithium hydride, lithium nitride, and n-butyl lithium. These compounds are soluble in the solvent used in the reaction system and can fully react with the precursor oxime.

[0081] In one embodiment, the solvent used in the reaction system after the precursor oxime and the lithium source are mixed is an aprotic solvent; optionally, the aprotic solvent includes one or more of an ether solvent, benzene, and tetrahydrofuran. An aprotic solvent refers to a solvent that cannot donate protons in the reaction system, and therefore does not affect the reaction between the precursor oxime and the lithium source. At the same time, the above-mentioned solvent does not react with the lithium source and the precursor oxime, which is conducive to the smooth preparation of the lithium supplement agent. In addition to the above-mentioned solvents, other inactive aprotic solvents can also be used.

[0082] Illustratively, the synthesis method of the lithium supplement agent includes the following steps: adding a precursor with a characteristic functional group of =N-OH to an organic solvent containing a lithium source, reacting for 1-4 hours under an inert atmosphere, and vacuum drying at 60-120°C after the reaction to obtain a crude product of the lithium supplement agent for lithium ion batteries. The crude product is ball milled, and the ball milling is high-energy ball milling with a rotation speed of 1000-2000 rpm / min to obtain a lithium supplement agent product for lithium ion batteries.

[0083] The present application also provides a battery, which includes any of the aforementioned positive electrode sheets; or a positive electrode sheet prepared using any of the aforementioned methods for preparing a positive electrode sheet.

[0084] During use, the lithium replenisher in the positive electrode releases lithium ions, which replenish the lithium ions consumed by the formation of the SEI film and the lithium ions consumed by the side reactions inside the battery, thereby improving the energy utilization rate of the battery and extending the cycle life of the battery. Figure 1 and Figure 2 After lithium replenishment, the product can be dissolved into the electrolyte system, so that pores are formed in the active layer of the positive electrode plate, that is, the battery includes a porous positive electrode plate, which improves the rate performance of the positive electrode plate.

[0085] Please refer to Figure 3 , Figure 3The figure is a schematic diagram of the exploded structure of a battery according to one or more embodiments. The battery 100 includes a housing 10 and a battery cell 20, with the battery cell 20 housed within the housing 10. The housing 10 is used to provide a storage space for the battery cell 20 and can have various structures. In some embodiments, the housing 10 can include a first portion 11 and a second portion 12, which overlap each other and together define a storage space for the battery cell 20. The second portion 12 can be a hollow structure with one end open. The first portion 11 can be a plate-like structure, with the first portion 11 overlapping the open side of the second portion 12, so that the first portion 11 and the second portion 12 jointly define a storage space. The first portion 11 and the second portion 12 can also be hollow structures with one end open, with the open side of the first portion 11 overlapping the open side of the second portion 12. Of course, the housing 10 formed by the first portion 11 and the second portion 12 can have various shapes, such as a cylinder, a rectangular parallelepiped, etc.

[0086] In the battery 100, there may be multiple battery cells 20, and the multiple battery cells 20 may be connected in series, in parallel, or in a hybrid connection. A hybrid connection refers to a combination of series and parallel connections among the multiple battery cells 20. The multiple battery cells 20 may be directly connected in series, in parallel, or in a hybrid connection, and then the entire battery cell 20 may be housed within the housing 10. Alternatively, the battery 100 may be constructed by first connecting multiple battery cells 20 in series, in parallel, or in a hybrid connection to form a battery module, which is then connected in series, in parallel, or in a hybrid connection to form a complete battery module, and then housed within the housing 10. The battery 100 may also include other structures, such as a busbar assembly for electrically connecting the multiple battery cells 20.

[0087] Each battery cell 20 may be a secondary battery or a primary battery, and may also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 20 may be cylindrical, flat, rectangular, or in other shapes.

[0088] Please refer to Figure 4 , Figure 4 FIG2 is a schematic diagram of the exploded structure of a battery cell according to one or more embodiments. A battery cell 20 is the smallest unit that makes up a battery. Figure 4 The battery cell 20 includes an end cap 21, a shell 22, an electrode assembly 23 and other functional components.

[0089] The end cap 21 is a component that covers the opening of the housing 22 to isolate the internal environment of the battery cell 20 from the external environment. The shape of the end cap 21 can be adapted to the shape of the housing 22 to fit the housing 22. Optionally, the end cap 21 can be made of a material with a certain hardness and strength (such as an aluminum alloy). This prevents the end cap 21 from deforming when subjected to compression or collision, thereby providing the battery cell 20 with greater structural strength and improved safety. The end cap 21 can be provided with functional components such as electrode terminals 21a. The electrode terminals 21a can be used to electrically connect to the electrode assembly 23 for inputting or outputting electrical energy from the battery cell 20. In some embodiments, the end cap 21 can also be provided with a pressure relief mechanism for relieving internal pressure when the internal pressure or temperature of the battery cell 20 reaches a threshold. The end cap 21 can also be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this. In some embodiments, an insulating member may be provided inside the end cap 21 to isolate the electrical connection components in the housing 22 from the end cap 21 to reduce the risk of short circuit. For example, the insulating member may be made of plastic, rubber, or the like.

[0090] The housing 22 is a component that cooperates with the end cap 21 to form the internal environment of the battery cell 20. This internal environment can be used to accommodate the electrode assembly 23, electrolyte, and other components. The housing 22 and end cap 21 can be separate components. An opening can be provided in the housing 22, and the end cap 21 is placed over the opening to form the internal environment of the battery cell 20. Alternatively, the end cap 21 and housing 22 can be integrated. Specifically, the end cap 21 and housing 22 can form a common connection surface before other components are inserted into the housing. When the interior of the housing 22 needs to be enclosed, the end cap 21 is placed over the housing 22. The housing 22 can have a variety of shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, or a hexagonal prism. Specifically, the shape of the housing 22 can be determined based on the specific shape and size of the electrode assembly 23. The housing 22 can be made of a variety of materials, such as copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and this embodiment of the present application does not impose any particular limitations on this.

[0091] The electrode assembly 23 is a component in the battery cell 100 where electrochemical reactions occur. One or more electrode assemblies 23 may be contained in the housing 22. The electrode assembly 23 is mainly formed by winding or stacking positive and negative electrode sheets, and a separator is usually provided between the positive and negative electrode sheets. The parts of the positive and negative electrode sheets with active materials constitute the main body of the electrode assembly, and the parts of the positive and negative electrode sheets without active materials each constitute a tab 23a. The positive and negative electrode tabs may be located together at one end of the main body or respectively at both ends of the main body. During the charge and discharge process of the battery, the positive active material and the negative active material react with the electrolyte, and the tabs 23a connect the electrode terminals to form a current loop.

[0092] In one embodiment, the electrode assembly includes any one of the aforementioned positive electrode sheets; or a positive electrode sheet prepared using any one of the aforementioned methods for preparing a positive electrode sheet.

[0093] In some embodiments, the positive electrode sheet includes a current collector and a positive active layer disposed on the current collector.

[0094] The positive electrode active layer includes a positive electrode active material, and 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 NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may 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.

[0095] Preferably, the positive electrode active material comprises lithium iron manganese phosphate (LiFe x Mn 1-x PO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium ferrous phosphate (LiFePO4), high nickel layered material Li 1+y (Ni a Co b Mn 1-a-b-c B c ) 1-y O2; where 0.05≤y≤0.05, 0.85≤a≤0.95, 0.01≤b≤0.10, 0≤c≤0.05, and B is Zn 2+ , Mg 2+ , Al 3+ , Cr 3+ , Sc 3+ , Ga 3+ , La 3+ , Sm 3+ , Ti 4+ , Zr 4+ , Nb 5+ , W 6+ One or more of .

[0096] When the above-mentioned positive electrode active materials are used in the positive electrode plates, the positive electrode plates need to be replenished with lithium. Taking a high-nickel-plus-silicon system battery as an example, its positive electrode active material is a high-nickel layered material, and the negative electrode active material is a silicon-based material. During the lithium insertion process of the silicon-based negative electrode material, theoretical calculations show that the complete lithiation of the silicon particles will produce a volume expansion of approximately 300%, which will lead to the formation of a larger SEI film area and irreversible consumption of lithium ions, resulting in a decrease in cycle life. In this case, adding the above-mentioned lithium replenisher to the positive electrode plate can effectively improve the energy density of the high-nickel-plus-silicon system battery. In addition, lithium iron manganese phosphate has a short cycle life and poor rate performance. By adding the above-mentioned lithium replenisher, the cycle life can be extended by replenishing lithium ions. After the lithium replenishment, the product dissolves into the electrolyte system, leaving almost no residue in the positive electrode plate. At the same time, pores are formed on the positive electrode plate, increasing the porosity of the positive electrode plate surface, which can improve the battery's rate performance.

[0097] In one embodiment, the porosity of the positive electrode sheet after the formation reaction is 20%-35%. The larger the porosity of the positive electrode sheet, the better the electrolyte infiltration effect.

[0098] In one embodiment, the active layer of the positive electrode material further includes a conductive agent and a binder; the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black and acetylene black; the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0099] Conductive agent imparts electrode conductivity. Positive electrode conductive material can include any conductive material, as long as it does not cause chemical change. Non-limiting examples of positive electrode conductive material include carbon-based materials (e.g., natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, etc.), metal-based materials (e.g., metal powder, metal fiber, etc., including, for example, copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives) and mixtures thereof. Alternatively, the conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, graphene, Ketjen black and acetylene black.

[0100] The binder improves the adhesion stability of the active layer and reduces the probability of powder loss. The binder can be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). Optionally, the binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

[0101] In some embodiments, the negative electrode sheet includes a current collector and a negative active layer disposed on the current collector.

[0102] The negative electrode active layer includes a negative electrode active material, which includes but is not limited to carbon-based negative electrode materials, silicon-based negative electrode materials, tin-based negative electrode materials, lithium titanate negative electrode materials, metallic lithium negative electrode materials, etc.; specifically includes but is not limited to graphite materials, silicon-carbon materials, graphite-silicon oxide materials, nano-silicon materials, silicon oxide materials and tin-based materials; more specifically includes natural graphite, artificial graphite, mesophase microcarbon beads (abbreviated as MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, spinel structured lithiated TiO2-Li4Ti5O 12 , one or more of Li-Al alloys.

[0103] In some embodiments, the negative electrode active layer may further include a binder, a conductive agent, and other optional additives. As an example, the conductive agent may be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, Super P (SP), graphene, and carbon nanofibers. As an example, the binder may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB). As an example, other optional additives may be thickening and dispersing agents (e.g., sodium carboxymethyl cellulose CMC-Na) and PTC thermistor materials.

[0104] In some embodiments, the material of the separator can be selected from 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.

[0105] In one embodiment, the electrolyte includes one or more of carbonate solvents and ether solvents.

[0106] Carbonates are generally small molecule cyclic or chain carbonates; including but not limited to one or more of ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, methylpropyl carbonate, dipropyl carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and fluorocarbonates; and may also be at least one ester solvent selected from γ-butyrolactone, dimethyl sulfite, ethyl acetate, methyl acetate, methyl butyrate, ethyl butyrate, methyl propionate, ethyl propionate, propyl acetate, and fluorocarboxylic acid esters.

[0107] Ether solvents include, but are not limited to, one or more of dimethyl ether, diethyl ether, tetrahydrofuran, methyltetrahydrofuran, ethylene oxide, 1,3-dioxolane, fluoroether, DME (ethylene glycol dimethyl ether), DEE (ethylene glycol diethyl ether), DEGDME (diethylene glycol dimethyl ether), TRGDME (triethylene glycol dimethyl ether), TEGDME (tetraethylene glycol dimethyl ether), dipropyl ether and dibutyl ether.

[0108] In other embodiments, the electrolyte may also include any one or a mixture of several of an amine solvent, a sulfone solvent, and a nitrile solvent. The amine solvent includes at least one of N-methylacetamide, N-methylformamide, dimethylformamide, and diethylformamide. The sulfone solvent includes at least one of dimethyl sulfoxide, cyclopentane sulfone, diphenyl sulfoxide, thionyl chloride, and dipropyl sulfone. The nitrile solvent includes at least one of acetonitrile, succinonitrile, adiponitrile, and glutaronitrile. The electrolyte is preferably a high-voltage resistant electrolyte, which has reduced acidity under high voltage, can facilitate the transmission of active ions, significantly reduce side reactions on the electrode surface, and improve battery stability.

[0109] In some embodiments, the electrolyte further includes an electrolyte salt, which can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0110] 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.

[0111] In some embodiments, the purpose of the electrochemical device of the present application is not particularly limited, and it can be used for any electronic device known in the prior art. The battery disclosed in the embodiment of the present application can be used for various energy storage systems using a battery as an electrical device for power supply or using a battery as an energy storage element. That is, a kind of electrical device is provided. In some embodiments, the electrical device of the present application can be used for, but not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a ship, a spacecraft, a lighting fixture, a toy, a game console, a clock, an electric tool, a flashlight, a camera, a large-scale household battery and a lithium-ion capacitor, etc.

[0112] Electrical equipment can choose battery cells, battery modules or battery packs according to its usage requirements.

[0113] Please refer to Figure 5 , Figure 5: is a structural diagram of a vehicle according to one or more embodiments. The vehicle 1000 can be a fuel vehicle, a gas vehicle or a new energy vehicle. The new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc. A battery 100 is provided inside the vehicle 1000. The battery 100 can be provided at the bottom, head or tail of the vehicle 1000. The battery 100 can be used to power the vehicle 1000. For example, the battery 100 can serve as an operating power source for the vehicle 1000. The vehicle 1000 can also include a controller 200 and a motor 300. The controller 200 is used to control the battery 100 to power the motor 300, for example, for starting, navigating and driving the vehicle 1000.

[0114] In some embodiments of the present application, the battery 100 can serve not only as an operating power source for the vehicle 1000, but also as a driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0115] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0116] 1. Preparation of lithium supplement, positive electrode and battery

[0117] Example 1:

[0118] 1. Preparation of lithium supplement: 10 g of diaminoglyoxime was dispersed in 100 ml of anhydrous ether, 1.5 equivalents of lithium methoxide were added, and the mixture was stirred for 2 h. The powder was filtered and dried under vacuum at 60° C. for 12 h. The powder was ball-milled at 1000 rpm to obtain lithium supplement I-1.

[0119] 2. Preparation of positive electrode sheet: 100g positive electrode active material (LiNi 0.9 Co 0.05 Mn 0.05O2), 2g of lithium supplement agent I-1 (2% by weight, particle size Dv50 = 1μm), 5g of conductive agent (super carbon black), and 1g of binder (PVDF) were mixed, and an appropriate amount of N-methylpyrrolidone (NMP) was added. The mixture was stirred at a speed of 400-1000r / s. The mixture was then wetted, kneaded, and dispersed to obtain a cathode slurry with a viscosity adjusted to 8000-13500mPa·s. The prepared slurry was coated on a current collector aluminum foil and then dried in an oven at a temperature of 80-110°C to control the water content to less than 150ppm to obtain a positive electrode sheet.

[0120] 3. Preparation of the electrolyte: In an inert atmosphere glove box with a water / oxygen concentration of less than 0.1 ppm, the organic solvents ethylene carbonate (EC) / ethyl methyl carbonate (EMC) / diethyl carbonate (DEC) were mixed in a ratio of 3:6:1 to form a base electrolyte, and then fully dried lithium hexafluorophosphate (LiPF6) was added. The mixture was stirred at room temperature for 30 minutes to completely dissolve the lithium hexafluorophosphate and the base electrolyte. Then, 3% by mass of calcium bis(trifluoromethylsulfonyl)imide (Ca(TFSI)2) was added by external addition to obtain an electrolyte.

[0121] 4. Preparation of negative electrode sheet: The negative electrode material (silicon oxide), binder (polyvinyl alcohol), and conductive agent (SP-Li) are mixed and ball-milled at a mass ratio of 90:5:5 to obtain a negative electrode slurry. The negative electrode slurry is coated on the surface of copper foil, rolled, and vacuum-dried at a temperature of 110°C overnight to obtain a negative electrode sheet;

[0122] 5. Preparation of the battery: The above-mentioned positive electrode sheet, separator, and negative electrode sheet are stacked in order, so that the separator is between the positive and negative electrode sheets to play an isolating role; then, the electrode assembly is wound to obtain the electrode assembly, the electrode lugs are welded to the electrode assembly, and the electrode assembly is placed in an aluminum shell and baked at 80°C to remove moisture. Then, the above-mentioned electrolyte is injected and sealed; finally, after standing, hot and cold pressing, formation (voltage 2.7-4.5V), shaping and other processes, the lithium-ion secondary battery of this embodiment is obtained.

[0123] Example 2-8:

[0124] The preparation of the lithium replenisher was changed on the basis of Example 1. The difference was that diaminoglyoxime was replaced with m-benzyldioxime, p-phenylenediaminedioxime, benzildioxime, 1,4-benzoquinonedioxime, 2,4-pentanedioxime, methylglyoxime, and polyethylenedioxime, respectively, to prepare lithium replenishers I-2 to I-8, as well as the corresponding positive electrode sheets and corresponding batteries. The specific reaction conditions are detailed in Table 1, which lists the reaction parameters and performance parameters of each embodiment and comparative example.

[0125] Examples 9-13:

[0126] The preparation of the positive electrode sheet was changed on the basis of Example 1, except that the weight proportion of the lithium supplement agent I-1 was changed from 2.0% to 4.0%, 8.0%, 8.0%, 12.0%, 0.5.0%, and 15.0%, respectively, to prepare the positive electrode sheet and the corresponding battery. The specific reaction conditions are detailed in Table 1.

[0127] Examples 14-15:

[0128] The preparation of the positive electrode sheet was changed on the basis of Example 1, except that the particle size of the lithium supplement agent was limited to Dv50 = 6 μm and 0.2 μm, respectively, to prepare the positive electrode sheet and the corresponding battery. The specific reaction conditions are detailed in Table 1.

[0129] Comparative Example 1:

[0130] The preparation of the positive electrode sheet was changed on the basis of Example 1, except that no lithium supplement agent was added to prepare the positive electrode sheet and the corresponding battery. The specific reaction conditions are shown in Table 1.

[0131] Comparative Example 2:

[0132] The preparation of the positive electrode sheet was changed on the basis of Example 1. The difference was that the second lithium replenisher I-1 was changed to Li5FeO4 lithium ion battery lithium replenisher to prepare the positive electrode sheet and the corresponding battery. The specific reaction conditions are detailed in Table 1.

[0133] 2. Positive electrode sheet test and battery electrochemical performance test

[0134] 1. Pole piece porosity test

[0135] After the cells were cycled, the electrodes were washed with ethylene glycol dimethyl ether (DME), vacuum-dried, and the porosity of the lithium-ion battery electrodes was measured using mercury intrusion porosimetry. The test results are shown in Table 1.

[0136] 2. First-effect test

[0137] Place the assembled battery cell on the electrochemical test channel and charge it at a constant current of 0.2C to the cut-off voltage, and record the capacity C c ; Stand for 30 minutes, discharge at 0.33C current to the cut-off voltage, and record the capacity C d , first effect = C d / C c ×100%. The test results are shown in Table 1.

[0138] The cut-off voltages for different cathode and anode systems are significantly different: the voltage window for lithium cobalt oxide (LiCoO2) cathode system is 2.6-4.2V, and the voltage window for lithium manganese iron phosphate (LiFe x Mn 1-xThe voltage window of the lithium iron phosphate (LiFePO4) system is 2.0-4.3V, the voltage window of the lithium iron phosphate (LiFePO4) system is 3.2-3.7V, and the voltage window of the ternary high nickel material system is 2.5-4.5V.

[0139] 3. 1C discharge capacity retention rate test

[0140] At a temperature of -20°C, charge at a constant current and constant voltage of 2C to 4.25V, cut off at 0.02C, let it stand for 5 minutes, and then discharge at a constant current of 0.7C to 2.8V. Cycle 1000 times under this condition, record the capacity corresponding to the 1C discharge in the 1000th cycle, and calculate the capacity retention rate in the 1000th cycle based on the discharge capacity of the first cycle and the initial thickness of the battery cell.

[0141] 4. 1000-cycle capacity retention test

[0142] The assembled battery cell was placed on the electrochemical test channel and cycled for 1000 cycles at a current of 0.5C and room temperature of 25°C. The capacity value C1000 was read and compared with the initial first-cycle capacity C10. The capacity retention rate was calculated using the formula: Capacity retention rate = C1000 / C10 × 100%. The capacity retention rate of the battery cell was recorded. The results are shown in Table 1.

[0143] Table 1 Reaction parameters and performance parameters of various embodiments and comparative examples

[0144]

[0145] 3. Analysis of the test results of positive electrode and battery electrochemical performance

[0146] 1. Porosity of positive electrode sheet

[0147] According to Comparative Example 1, the initial porosity of the positive electrode plate is about 25%. The plate porosity is affected by the total specific surface area of the lithium supplement agent, which is reflected in the weight and particle size of the lithium supplement agent.

[0148] Compared with Comparative Example 1, the addition of a lithium supplement enhancer can increase the porosity of the positive electrode sheet, while also improving the electrode's kinetic performance and capacity retention. The test results of Examples 1 and 9-13 show that the greater the weight percentage of the lithium supplement, the greater the porosity of the positive electrode sheet.

[0149] The preferred range of the particle size Dv50 of the lithium supplement is 0.5-3.0 μm, which is smaller than the particle size of the positive electrode active material and larger than the particle size of the conductive agent carbon black, and can form submicron and micron-sized pores after dissolution.

[0150] 2. First effect

[0151] Compared with Comparative Example 1, Examples 1-8 were added with the lithium supplement agent of the present application. The test results show that the lithium supplement agents I-1 to I-8 of the present application all reduced the first efficiency of the battery. This is because during the first cycle of charging, the lithium supplement agent provides additional capacity, thereby increasing the charging capacity. At the same time, the first cycle discharge capacity is related to the release of lithium from the anode. Since the anode has not changed, the discharge capacity remains basically unchanged. According to the first efficiency calculation formula: First efficiency = C d / C c ×100%, so the initial efficiency will be reduced. The lower the initial efficiency, the more additional capacity the lithium supplement agent provides. Compared with Comparative Example 2, lithium supplement agents I-1 to I-8 in this application provide more additional capacity, and therefore have a better lithium supplement effect.

[0152] In Examples 1-8, different lithium supplements have different lithium supplement effects. The greater the lithium ion density of the lithium supplement, the better the lithium supplement effect. For example, the lithium ion density of lithium supplement I-7 is 2 / 107, and the lithium ion density of I-1 is 2 / 130. Therefore, the first efficiency of the battery in Example 7 is lower. Taking I7 as an example, the lithium ion density of lithium supplement is 2 / 107; similarly, the lithium ion density of lithium supplement I1 is 2 / 130.

[0153] 3. Capacity retention rate

[0154] Compared with Comparative Examples 1 and 2, the lithium supplement agent in the present application was added to Examples 1-8. The test results show that the lithium supplement agents I-1 to I-7 in the present application can improve the capacity retention rate of the battery (including the 1C discharge capacity retention rate and the 1000-cycle capacity retention rate), thereby improving the cycle life of the battery, and the effect is better than that of the conventional lithium supplement agent Li5FeO4.

[0155] The analysis results of the above embodiments show that the porosity of the positive electrode plate provided in this application is improved, and the battery using the above positive electrode plate has a lower initial efficiency and a higher capacity retention rate, which is beneficial to improving the energy utilization rate of the battery and extending the cycle life of the battery. This is attributed to the special properties of the lithium supplement agent applied to the battery positive electrode plate proposed in this application.

[0156] The above description is only an implementation method of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the description and drawings of this application, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A positive electrode plate, characterized in that: include: grassroots; The active layer is located on the base layer, and the active layer includes a positive electrode active material and a lithium supplement agent, and the lithium supplement agent includes Wherein R1, R2, and R3 contain -C=N-OLi or at least one double bond, aromatic group, or amino group that forms a conjugated structure with -C=N-OLi.

2. The positive electrode sheet according to claim 1, characterized in that: in, R1, R2, and R3 include any one of an alkyl group having 2 to 15 carbon atoms or a polymer group having a number average molecular weight Mn≤15W.

3. The positive electrode sheet according to claim 1 or 2, characterized in that: Any one of R1, R2, and R3 contains at least one -C=N-OLi.

4. The positive electrode sheet according to any one of claims 1 to 3, characterized in that: The lithium supplement includes one or more of diaminoglyoxime lithium salt, m-benzyldioxime lithium salt, p-phenylenediamide oxime lithium salt, benzildioxime lithium salt, 1,4-benzoquinonedioxime lithium salt, 2,4-butanedioxime lithium salt, methylglyoxime lithium salt, and polyacrylamidoxime lithium salt.

5. The positive electrode sheet according to any one of claims 1 to 4, characterized in that: The lithium supplement agent accounts for 1.0% to 12.0% of the active layer by weight.

6. The positive electrode sheet according to any one of claims 1 to 5, characterized in that: The amount of the lithium supplement agent added is M=1 / Cb[(1-CEa)Ma×Ca+(CEc-CEa)Mc×Cc]. Wherein, Cb is the charge capacity of the lithium supplement, CEa is the first effect of the anode on the lithium half-cell; Ma is the mass of the anode, Ca is the lithium discharge capacity of the anode, CEc is the first effect of the cathode on the lithium half-cell, Mc is the mass of the cathode, and Cc is the lithium discharge capacity of the cathode.

7. The positive electrode sheet according to any one of claims 1 to 6, characterized in that: The particle size Dv50 of the lithium supplement agent is 0.5-3.0 μm.

8. The positive electrode sheet according to any one of claims 1 to 7, characterized in that: The infrared detection results of the positive electrode include 1665cm -1 (C=N), 945cm -1 (NO) and 1500cm -1 The infrared characteristic peak of (N=O) bond.

9. The positive electrode sheet according to claim 8, characterized in that: The thickness of the active layer on either side of the positive electrode plate is 120-450 μm.

10. The positive electrode sheet according to any one of claims 1 to 9, characterized in that: The positive electrode active material includes lithium manganese iron phosphate (LiFe x Mn 1-x PO4), lithium cobalt oxide (LiCoO2), lithium manganese oxide (LiMn2O4), lithium iron phosphate (LiFePO4), high nickel layered material Li 1+y (Ni a Co b Mn 1-a-b-c B c ) 1-y O2; where 0.05≤y≤0.05, 0.85≤a≤0.95, 0.01≤b≤0.10, 0≤c≤0.05, and B is Zn 2+ , Mg 2+ , Al 3+ , Cr 3+ , Sc 3+ , Ga 3+ , La 3+ , Sm 3+ , Ti 4+ , Zr 4+ , Nb 5+ , W 6+ One or more of .

11. The positive electrode sheet according to any one of claims 1 to 10, characterized in that: The active layer further comprises a conductive agent and a binder; The conductive agent includes one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, graphene, Ketjen black and acetylene black; The binder includes one or more of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, and polyurethane.

12. A method for preparing a positive electrode sheet, characterized in that: include: Mixing the positive electrode active material, the lithium supplement agent and the solvent to obtain a positive electrode slurry; The positive electrode slurry is coated on the base layer and dried to obtain the positive electrode sheet; wherein the lithium supplement agent includes Wherein, R1, R2, and R3 contain -C=N-OLi or at least one double bond, aromatic group, or amino structure that forms a conjugated structure with -C=N-OLi.

13. The method for preparing a positive electrode sheet according to claim 12, wherein: The precursor oxime is mixed with a lithium source and reacted to obtain the lithium supplement agent. The precursor oxime includes Wherein, R1, R2, and R3 contain -C=N-OLi or at least one double bond, aromatic group, or amino structure that forms a conjugated structure with -C=N-OLi.

14. The method for preparing a positive electrode sheet according to claim 13, wherein: The lithium source includes one or more of lithium ethoxide, lithium methanolate, lithium hydride, lithium nitride and n-butyl lithium.

15. The method for preparing a positive electrode sheet according to claim 13, wherein: After the precursor oxime is mixed with the lithium source, the solvent used in the reaction system is an aprotic solvent; optionally, the aprotic solvent includes one or more of an ether solvent, benzene and tetrahydrofuran.

16. A battery, characterized in that: A positive electrode sheet comprising the positive electrode sheet according to any one of claims 1 to 11; or a positive electrode sheet prepared by the method for preparing the positive electrode sheet according to any one of claims 12 to 15.

17. The battery according to claim 16, characterized in that After the formation reaction, the porosity of the positive electrode sheet is 20% to 35%.

18. An electrical device, characterized in that: A battery comprising the battery according to claim 16 or 17.

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