Lithium supplement and preparation method therefor, positive electrode sheet, battery, and electric device

Abstract

A lithium supplement and a preparation method therefor, a positive electrode sheet, and a battery. The lithium supplement comprises: a core, wherein the core comprises LiaMbOc, wherein a is 2-6, b is 0-4, c is 1-6, and M comprises at least one of Mg, Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, and Sn; and a coating layer, wherein the coating layer at least covers part of the surface of the core, and the coating layer contains at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound.

Description

Lithium supplement and preparation method thereof, positive electrode sheet, battery, and electrical device Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular to a lithium supplement and a preparation method thereof, a positive electrode sheet, a battery, and an electrical device. Background Art

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

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

[0004] Application Contents

[0005] In the first aspect of the present application, a lithium supplement is proposed, comprising: a core, the core comprising Li a M b O c , wherein a is 2-6, b is 0-4, c is 1-6, and M includes at least one of Mg, Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, and Sn; a coating layer, the coating layer at least covers a portion of the surface of the core, and the coating layer contains at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound. The lithium supplement agent easily reacts with water, air, and the like, thereby generating inert alkaline impurities on the surface of the lithium supplement agent, significantly reducing the active lithium ion content and kinetic performance of the lithium supplement agent. The lithium supplement agent in this application can consume water and acidic substances in the battery during the charge and discharge cycle of the battery and slowly release lithium ions to achieve a long-term lithium supplement effect.

[0006] In some embodiments, the coating layer satisfies at least one of the following conditions:

[0007] (1) The silazane compound satisfies Formula 1:

[0008] wherein R1 and R2 are each independently C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl;

[0009] (2) The siloxane compound satisfies Formula 2:

[0010] wherein R3 is C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl;

[0011] (3) The sulfonic acid silane compound satisfies Formula 3:

[0012] wherein R4 is F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 alkynyl, C6-C8 phenyl, or C2-C4 cyano-substituted alkyl;

[0013] (4) The carbodiimide compound satisfies Formula 4:

[0014] Wherein, R5 and R6 are independently C1-C6 alkyl, C3-C4 cycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl. Thus, the water and acid removal effect of the lithium supplement agent can be further improved.

[0015] In some embodiments, the coating layer satisfies at least one of the following conditions: (1) the silazane compound includes at least one of vinylsilazane and hexamethyldisilazane; (2) the siloxane compound includes at least one of dimethylsiloxane and vinylsiloxane; (3) the sulfonic acid silane compound includes at least one of trimethylsilylsulfonate, trimethylphenylsilylsulfonate, and trimethylpropylenesilylsulfonate; (4) the carbodiimide compound includes at least one of N,N'-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide. Thus, the coating layer has a better coating effect on the core.

[0016] In some embodiments, the mass fraction of the coating layer in the lithium supplement agent is 2%-8%, thereby facilitating an increase in the lithium supplement gram capacity of the lithium supplement agent.

[0017] In some embodiments, the mass fraction of the coating layer in the lithium supplement agent is 3.3%-4.5%, thereby increasing the lithium supplement capacity of the lithium supplement agent and achieving long-term lithium supplementation.

[0018] In some embodiments, the coating layer has a thickness of 0.3 μm to 3 μm, thereby facilitating timely release of lithium ions in the core.

[0019] In some embodiments, the coating layer has a thickness of 0.5 μm to 1 μm, thereby facilitating timely release of the lithium-replenishing capacity of the core.

[0020] In some embodiments, the core comprises Li2M1O2, wherein M1 comprises at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or, the core comprises Li2M2O3, wherein M2 comprises at least one of Ni, Co, Mn, Fe, Mo, Sn, Cr, Zr, Si, Cu, and Ru; and / or, the core comprises Li2M3O4, wherein M3 comprises at least one of Ni, Co, Mn, Fe, Cu, Sn, Cr, V, and Nb; and / or, the core comprises Li3M4O4, wherein M4 includes at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or the core includes Li5M5O4, wherein M5 includes at least one of Ni, Co, Mn, Fe, Mo, Cu, Sn, Cr, and Al; and / or the core includes Li5M6O6, wherein M6 includes at least one of Ni, Cu, Mn, Fe, Cr, Mo, Zn, Sn, Mg, and Ca; and / or the core includes Li6M7O4, wherein M7 includes at least one of Ni, Co, Mn, Fe, Cu, and Ru. Thus, the lithium supplementation capacity of the lithium supplementation agent can be increased.

[0021] In some embodiments, the Dv50 particle size of the core is 2 μm to 10 μm, thereby facilitating the utilization of the lithium supplementation capacity of the core.

[0022] In some embodiments, the core has a Dv50 particle size of 3 μm to 7 μm, thereby facilitating full utilization of the lithium supplementation capacity of the core.

[0023] In a second aspect of this application, a method for preparing the aforementioned lithium supplement is provided, comprising: mixing a core with a compound containing at least one of a silicon-oxygen bond, a silicon-nitrogen bond, and an imine bond to obtain a mixture; and heating the mixture to obtain the lithium supplement. Thus, the aforementioned lithium supplement can be prepared using a relatively simple method.

[0024] In some embodiments, the compound includes at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound, thereby facilitating the formation of a relatively firm coating layer.

[0025] In some embodiments, the mass fraction of the compound in the mixture is 5%-15%, thereby improving the coating integrity of the coating layer on the surface of the inner core.

[0026] In some embodiments, the mixing step further includes: washing the core to remove residual alkali on the surface of the core, thereby reducing problems such as positive electrode slurry gelation caused by the lithium supplement.

[0027] In a third aspect, the present application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material and a lithium supplement, wherein the lithium supplement comprises the aforementioned lithium supplement or a lithium supplement prepared using the aforementioned method. Thus, the positive electrode plate possesses all the features and advantages of the aforementioned lithium supplement and method for preparing the lithium supplement, which will not be further elaborated here.

[0028] In a fourth aspect of the present application, the present application provides a battery comprising the aforementioned positive electrode sheet. Thus, the battery includes all the features and advantages of the aforementioned positive electrode sheet, which will not be elaborated here.

[0029] In a fifth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device includes all the features and advantages of the aforementioned battery, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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:

[0031] FIG1 is a schematic structural diagram of a lithium supplement according to one embodiment of the present application;

[0032] FIG2 is a schematic flow diagram of a method for preparing a lithium supplement according to one embodiment of the present application;

[0033] FIG3 is a schematic flow chart of a method for preparing a lithium supplement according to another embodiment of the present application;

[0034] FIG4 is a schematic diagram of a battery cell according to an embodiment of the present application;

[0035] FIG5 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG4 ;

[0036] FIG6 is a schematic diagram of a battery module according to an embodiment of the present application;

[0037] FIG7 is a schematic diagram of a battery pack according to an embodiment of the present application;

[0038] FIG8 is an exploded view of the battery pack shown in FIG7 according to an embodiment of the present application;

[0039] FIG9 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0040] Description of reference numerals:

[0041] 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery cell;

[0042] 51 housing; 52 electrode assembly; 53 top cover assembly;

[0043] 100: core; 200: cladding. DETAILED DESCRIPTION

[0044] Below, the lithium supplement agent and its preparation method, positive electrode sheet, battery, and electric device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0045] " scope " disclosed in the application is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 are listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0046] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0047] 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.

[0048] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a 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. For example, a 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.

[0049] In the description of this application, “plurality” means two or more.

[0050] In the description of this application, "A and / or B" may include the case of A alone, the case of B alone, or any of the cases of A and B, where A and B are only used for example, and may be any technical feature connected by "and / or" in this application.

[0051] On the one hand, lithium supplements can replace the loss of active lithium ions caused by the formation of SEI during the initial charge and discharge process, ensuring that the battery has sufficient reversible active lithium ions during subsequent cycles, thereby improving the battery's energy density. On the other hand, lithium supplements can also be used to compensate for the lithium consumption during the cycle, improving the battery's cycle performance. Lithium supplements can be divided into positive electrode lithium supplements and negative electrode lithium supplements based on their functional location in the battery.

[0052] Although positive electrode lithium supplements have advantages such as ease of preparation and stable properties, they have a narrow processing window. Specifically, positive electrode lithium supplements are prone to reacting with water, air, and other substances, generating inert alkaline impurities on the surface of the supplement, significantly reducing the active lithium ion content and kinetic performance of the supplement. Therefore, it is necessary to strictly control the water content of the environment in which the supplement is located. In addition, the active lithium ions in the supplement are completely released during the initial charge and discharge process of the battery, making it impossible for the supplement to continuously replenish active lithium ions in the later stages of the charge and discharge cycle, thereby significantly reducing the cycle performance of the battery in the later stages of use. Moreover, when the active lithium ions in the supplement are completely released during the initial charge and discharge process, the negative electrode of the battery needs to increase the amount of negative electrode active material accordingly to provide sufficient lithium ion deintercalation sites, resulting in an increase in battery production costs.

[0053] For batteries, the water content inside the battery also needs to be strictly controlled. For example, when the electrolyte contains lithium hexafluorophosphate, when the water content inside the battery is high, the water will react with the lithium hexafluorophosphate to produce hydrogen fluoride gas. Hydrogen fluoride is extremely corrosive and can cause serious damage to the battery's positive and negative electrodes. In addition, when the water content inside the battery is high, the formation of the SEI film will produce gases such as carbon dioxide and carbon monoxide, leading to serious flatulence problems in the battery. Reducing the water content in the production and use environments will greatly increase the production cost of the battery, which is not conducive to industrial application.

[0054] In the present application, while meeting the basic requirement of improving the first-cycle efficiency of the battery by adding a lithium supplement, a coating layer with water and acid removal properties is provided on the surface of the core with a high lithium supplement capacity. This can consume water and acidic substances in the external environment, such as water and acidic substances in the lithium supplement storage environment, water and acidic substances in the electrolyte, etc., through the reaction between the coating layer and water and / or acidic substances, thereby eliminating the process steps of reducing the water content in the production environment and the use environment, greatly reducing the production cost of the lithium supplement, and widening the processing window of the lithium supplement; and The setting of the coating layer enables the lithium replenisher to have the effect of long-term release of active lithium ions. Specifically, as the consumption reaction of the coating layer with water and acidic substances continues, the surface of the core covered by the coating layer is continuously exposed to the electrolyte, thereby releasing lithium ions. That is, the coating layer can achieve the effect of removing water and acid while controlling the release of the lithium replenishment capacity of the core, so that the lithium replenisher can slowly release lithium ions during the charge and discharge cycle of the battery, achieving a long-term lithium replenishment effect, and there is no need to excessively increase the amount of negative electrode active material in the negative electrode sheet, thereby reducing the production cost of the battery.

[0055] In the first aspect of the present application, the present application proposes a lithium supplement, referring to FIG1 , comprising: a core 100, the core 100 including Li aM b O c , wherein a is 2-6, b is 0-4, c is 1-6, and M includes at least one of Mg, Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, and Sn; the coating layer 200 covers at least a portion of the surface of the core 100, and the coating layer 200 comprises at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound.

[0056] Silazane compounds contain silicon-nitrogen bonds; siloxane compounds and sulfonic acid silane compounds both contain silicon-oxygen bonds; and carbodiimide compounds contain imine bonds. The lithium supplement in this application improves the first-cycle efficiency of the battery while utilizing a specific coating structure. Specifically, the silicon-oxygen bonds, silicon-nitrogen bonds, and imine bonds in the coating can react with active hydrogen ions in water and acidic substances and break bonds, thereby consuming water and acidic substances in the environment in which the lithium supplement is located, such as water and acidic substances in the storage environment of the lithium supplement, water and acidic substances in the electrolyte, etc., and slowly exposing the core of the lithium supplement to achieve a long-term lithium supplement effect, thereby improving the first-cycle efficiency, cycle performance, and storage performance of the battery.

[0057] As an example, a can be 2, 3, 4, 5 or 6.

[0058] As an example, b can be 0, 1, 2, 3, or 4.

[0059] When b is 0, the core is a binary lithium-containing compound. As an example, the binary lithium-containing compound may include Li2O and Li2O2.

[0060] As an example, c can be 1, 2, 3, 4, 5 or 6.

[0061] Unless otherwise specified, in the above chemical formula, when M is two or more elements, the above-mentioned numerical range for b is not only a limit on the stoichiometric number of each element serving as M, but also a limit on the sum of the stoichiometric numbers of each element serving as M. For example, when M is two or more elements M1, M2, M3, ..., Mn, the stoichiometric numbers b1, b2, b3, ..., bn of M1, M2, M3, ..., Mn must each fall within the numerical range for b specified in this application, and the sum of b1, b2, b3, ..., bn must also fall within this numerical range.

[0062] In some embodiments, the core comprises Li2M1O2, wherein M1 comprises at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or, the core comprises Li2M2O3, wherein M2 comprises at least one of Ni, Co, Mn, Fe, Mo, Sn, Cr, Zr, Si, Cu, and Ru; and / or, the core comprises Li2M3O4, wherein M3 Includes at least one of Ni, Co, Mn, Fe, Cu, Sn, Cr, V, and Nb; and / or, the core includes Li3M4O4, wherein M4 includes at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or, the core includes Li5M5O4, wherein M5 includes at least one of Ni, Co, Mn, Fe, Mo, Cu, Sn, Cr, and Al; and / or, the core includes Li5M6O6, wherein M6 includes at least one of Ni, Cu, Mn, Fe, Cr, Mo, Zn, Sn, Mg, and Ca; and / or, the core includes Li6M7O4, wherein M7 includes at least one of Ni, Co, Mn, Fe, Cu, and Ru.

[0063] It can be understood that M1, M2, M3, M4, M5, M6, and M7 are all M elements contained in the core of the lithium supplement.

[0064] When the core satisfies at least one of the above chemical formulas, it is a transition metal oxide lithium salt, known as a ternary lithium-containing compound. Ternary lithium-containing compounds contain two or more lithium ions and, compared to organic lithium-containing compounds, have higher irreversible capacity and better stability in air. By combining different transition metal elements, the core's decomposition potential can be controlled, facilitating the release of active lithium ions.

[0065] In some embodiments, the Dv50 particle size of the inner core is 2 μm to 10 μm. In other embodiments, the Dv50 particle size of the inner core is 3 μm to 7 μm.

[0066] As an example, the Dv50 of the core may be 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm or 10μm.

[0067] When the Dv50 particle size of the core is 2μm-10μm, the core particle size is moderate, the core has a higher lithium replenishing capacity, it is easy to form a relatively complete coating layer on the surface of the core, it is also conducive to the release of active lithium ions, and the kinetic performance is better.

[0068] The aforementioned Dv50 particle size refers to the particle size corresponding to when the cumulative volume distribution percentage of the particles reaches 50%.

[0069] The "particle size" in this application has a meaning well known in the art and can be measured using instruments and methods well known in the art. As an example, the particle size of the kernel can be measured by laser diffraction particle size analysis. For example, the particle size of the kernel can be measured with reference to the standard GB / T19077-2016 using a laser particle size analyzer (such as Malvern Master Size 3000). Specifically, the coating material on the surface of the kernel can be removed by the following method to reduce the influence of the coating structure on the measurement of the kernel particle size: the lithium supplement agent is placed in an argon atmosphere, and the ambient temperature of the lithium supplement agent is gradually increased from 35°C to 500°C, so that the coating material on the surface of the kernel is fully decomposed and volatilized at high temperature, thereby obtaining a kernel without a surface coating.

[0070] In some embodiments, the coating layer contains at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound.

[0071] Silazane compounds contain silicon-nitrogen bonds; siloxane compounds and sulfonic acid silane compounds both contain silicon-oxygen bonds; and carbodiimide compounds contain imine bonds, which can react with water and acidic substances during the storage process and / or charge and discharge cycle by breaking the bond, thereby achieving slow exposure of the core.

[0072] As an example, the imine bond in the carbodiimide compound is easily broken by an addition reaction with active hydrogen. For example, the carbodiimide compound can react with water in the electrolyte to generate an amide product to remove excess water in the electrolyte.

[0073] In some embodiments, the silazane compound satisfies Formula 1:

[0074] Wherein, R1 and R2 are independently C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl.

[0075] It is understood that, in addition to being connected to N, Si in Formula 1 can also be connected to other atoms. For example, Si in Formula 1 can also be connected to C. Specifically, in addition to being connected to N, Si can also be connected to three methyl groups (-CH3). When R1 and R2 are the above-mentioned functional groups, the number of carbon atoms and molecular weight of the silazane compound are moderate, which is conducive to the breaking of the silicon-nitrogen bond and improving the coating integrity of the silazane compound on the core surface.

[0076] In some embodiments, the siloxane compound satisfies Formula 2:

[0077] Wherein, R3 is C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl.

[0078] When R3 is the above functional group, the carbon number and molecular weight of the siloxane compound are moderate, which is conducive to the breaking of the silicon-oxygen bond and improving the coating integrity of the siloxane compound on the core surface.

[0079] It can be understood that, in addition to being connected to O, Si in Formula 2 can also be connected to other atoms. For example, Si in Formula 2 can also be connected to C. Specifically, in addition to being connected to O, Si can also be connected to three methyl groups (-CH3).

[0080] In some embodiments, the sulfonic acid silane compound satisfies Formula 3:

[0081] Wherein, R4 is F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 alkynyl, C6-C8 phenyl or C2-C4 cyano-substituted alkyl.

[0082] When R4 is the above-mentioned functional group, the steric hindrance of the sulfonic acid silane compound is small, which is beneficial to improving the coating integrity of the sulfonic acid silane compound on the core surface and the density of the coating layer, thereby achieving a better lithium replenishment sustained-release effect.

[0083] It can be understood that, in addition to being connected to O, Si in Formula 3 can also be connected to other atoms. For example, Si in Formula 3 can also be connected to C. Specifically, in addition to being connected to O, Si can also be connected to three methyl groups (-CH3).

[0084] In some embodiments, the carbodiimide compound satisfies Formula 4:

[0085] Wherein, R5 and R6 are each independently a C1-C6 alkyl, a C3-C4 cycloalkyl, a C2-C4 alkenyl or a C2-C4 alkynyl.

[0086] When R5 and R6 are the above-mentioned functional groups, the steric hindrance of the carbodiimide compound is small, which is beneficial to improving the coating integrity of the carbodiimide compound on the core surface and the density of the coating layer, thereby achieving a better lithium replenishment sustained-release effect.

[0087] In some embodiments, the coating layer satisfies at least one of the following conditions: (1) the silazane compound includes at least one of vinylsilazane and hexamethyldisilazane; (2) the siloxane compound includes at least one of dimethylsiloxane and vinylsiloxane; (3) the sulfonic acid silane compound includes at least one of trimethylsulfonic acid silane, trimethylphenylsulfonic acid silane, and trimethylpropylenesulfonic acid silane; (4) the carbodiimide compound includes at least one of N,N'-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0088] When the substance in the coating layer meets the aforementioned conditions, the coating layer has a high density and coating integrity. As the coating layer gradually reacts with water and acidic substances, the inner core is gradually exposed, and then plays a lithium replenishing role, reducing the problem that the coating layer is not consumed due to poor coating integrity, but the inner core has already played a lithium replenishing role in advance, and the lithium replenishment sustained-release effect cannot be achieved well.

[0089] In some embodiments, the mass fraction of the coating layer in the lithium supplement agent is 2%-8%. In other embodiments, the mass fraction of the coating layer in the lithium supplement agent is 3.3%-4.5%.

[0090] As an example, the mass fraction of the coating layer in the lithium supplement may be 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4%, 4.1%, 4.2%, 4.3%, 4.4%, or 4.5%.

[0091] When the mass fraction of the coating layer in the lithium supplement agent is 2%-8%, the mass ratio of the coating layer to the core is appropriate. The lithium supplement agent can achieve a sustained-release lithium supplement effect while also having a higher lithium supplement gram capacity, thereby achieving long-term lithium supplementation.

[0092] The "mass fraction" in this application has a meaning well known in the art and can be measured using instruments and methods well known in the art. As an example, the mass fraction of the coating layer in the lithium supplement agent can be obtained by thermogravimetric analyzer (TG) testing. Specifically, the test can be carried out according to the following method: 1. Sample preparation: weigh 10 mg of sample and place it in an Al2O3 crucible and shake it flat; 2. Parameter setting: argon atmosphere, purge gas 50 mL / min, protective gas 20 mL / min; 3. Temperature rise program: heating rate 10°C / min, temperature range 35°C-500°C. The mass m1 lost by the lithium supplement agent during the aforementioned thermal gravimetric test is read by the instrument, and the mass of the test sample is m2. The mass fraction of the coating layer in the lithium supplement agent can be obtained by dividing m1 by m2.

[0093] In some embodiments, the coating layer has a thickness of 0.3 μm to 3 μm. In other embodiments, the coating layer has a thickness of 0.5 μm to 1 μm.

[0094] As an example, the thickness of the coating layer can be 0.3μm, 0.4μm, 0.5μm, 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1.0μm, 1.1μm, 1.2μm, 1.3μm, 1.4μm, 1.5μm, 1.6μm, 1.7μm, 1.8μm, 1.9μm, 2.0μm, 2.1μm, 2.2μm, 2.3μm, 2.4μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm or 3μm.

[0095] When the thickness of the coating layer is 0.3μm-3μm, the coating layer can better and completely cover the surface of the core. Under the premise of meeting the low resistance of the lithium supplement agent, the coating layer can fully react with water and / or acidic substances to consume as much water and acidic substances in the external environment as possible, thereby improving the water and acid removal effect of the lithium supplement agent; at the same time, the moderate thickness of the coating layer is also conducive to the escape of active lithium ions and the full release of the lithium supplement capacity of the core, thereby improving the kinetic performance of the lithium supplement agent and reducing problems such as dendrite growth caused by too fast release of the lithium supplement capacity of the core and reduced cycle life due to too slow release.

[0096] The "thickness" in this application has a well-known meaning in the art and can be measured using instruments and methods well-known in the art. As an example, the thickness of the coating layer in the lithium supplement can be measured using a transmission electron microscope (TEM).

[0097] In the second aspect of the present application, the present application proposes a method for preparing the aforementioned lithium supplement, thereby, the aforementioned lithium supplement can be prepared by a relatively simple method. Specifically, referring to FIG2 , the method for preparing the lithium supplement comprises:

[0098] S100: mixing the core with a compound containing at least one of a silicon-oxygen bond, a silicon-nitrogen bond, and an imine bond to obtain a mixture.

[0099] In some embodiments, in this step, the core is mixed with a compound containing at least one of a silicon-oxygen bond, a silicon-nitrogen bond, and an imine bond to obtain a mixture, wherein the compound includes at least one of a silazane compound, a siloxane compound, a sulfonic acid silane compound, and a carbodiimide compound.

[0100] As an example, the silazane compound includes at least one of vinylsilazane and hexamethyldisilazane; the siloxane compound includes at least one of dimethylsiloxane and vinylsiloxane; the sulfonic acid silane compound includes at least one of trimethylsulfonic acid silane, trimethylphenylsulfonic acid silane, and trimethylpropylenesulfonic acid silane; the carbodiimide compound includes at least one of N,N'-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

[0101] When the core is mixed with the aforementioned compound, the substances in the obtained mixture are dispersed more evenly, which is conducive to forming a dense coating layer uniformly covering the surface of the core after heating.

[0102] In some embodiments, the mass fraction of the compound in the mixture is 5%-15%.

[0103] As an example, the mass fraction of the compound in the mixture can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, or 15%.

[0104] It is understandable that during the heating process of the mixture of the core and the aforementioned compounds, some components of the compounds will volatilize, thereby causing the mass fraction of the coating layer in the final lithium supplement to be lower than the mass fraction of the corresponding compounds in the mixture.

[0105] S200: heating treatment

[0106] In some embodiments, the mixture of the core and the aforementioned compound is subjected to a heat treatment to allow the compound to self-assemble on the surface of the core under high temperature conditions, thereby forming a coating layer on the surface of the core to obtain a lithium supplement.

[0107] In some embodiments, the heat treatment may be performed under a nitrogen atmosphere. In other embodiments, the heat treatment may also be performed under an inert gas atmosphere.

[0108] In some embodiments, the temperature of the heat treatment is 200°C-400°C.

[0109] As an example, the temperature of the heat treatment can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃ or 400℃.

[0110] When the temperature of the heating treatment is 200° C.-400° C., it is helpful for the compound to self-assemble on the surface of the inner core, thereby improving the firmness of the connection between the compound and the inner core surface and improving the coating integrity of the compound on the inner core surface.

[0111] In some embodiments, the heating rate of the heat treatment is 3°C / min-20°C / min.

[0112] As an example, the heating rate of the heat treatment can be 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min, 16℃ / min, 17℃ / min, 18℃ / min, 19℃ / min or 20℃ / min.

[0113] When the heating rate of the heating treatment is 3°C / min-20°C / min, the duration of the heating treatment can be shortened and the yield can be improved.

[0114] In some embodiments, the heating treatment time is 1 hour to 5 hours.

[0115] As an example, the heating treatment time may be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h.

[0116] When the heating treatment time is 1h-5h, it is beneficial for the compound to be fully coated on the surface of the inner core. At the same time, maintaining the above time at high temperature can effectively improve the density of the coating layer and reduce the inner core surface directly exposed to the outside.

[0117] In some embodiments, after the heat treatment is completed, the cooling rate is 2° C. / min-10° C. / min.

[0118] As an example, after the heat treatment is completed, the cooling rate can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min.

[0119] In some embodiments, after the heating treatment is completed, the temperature may be lowered to room temperature.

[0120] In some embodiments, referring to FIG3 , the method for preparing a lithium supplement may further include:

[0121] S110: Cleaning of kernels before mixing

[0122] In some embodiments, the core is cleaned in this step to remove residual alkali on the surface of the core.

[0123] The surface of the core material is prone to retaining alkaline substances left over from the preparation process. The residual alkali on the surface of the core is prone to react with water and carbon dioxide in the air during use, or with water and carbon dioxide in the slurry after being added to the positive electrode slurry, thereby forming inert impurities such as lithium hydroxide and lithium carbonate on the surface of the core. The generation of impurities will increase the alkalinity of the core on the one hand, and then cause the binder to gel during the preparation of the positive electrode slurry; on the other hand, affected by the surface side reaction layer (that is, the impurity layer generated by the aforementioned core contacting water and carbon dioxide), the active lithium ion content and kinetics of the core will decrease, ultimately leading to a significant decrease in the lithium replenishment capacity of the lithium replenisher; residual alkaline impurities on the surface of the core will also cause serious gas production problems in the lithium-ion battery during the charge and discharge process, thereby causing the battery to swell and deform, shorten the cycle life and other problems.

[0124] By cleaning the core, the alkaline substances remaining on the core surface can be removed, reducing many defects caused by the residual alkali on the core surface.

[0125] As an example, the cleaning process may include, under conditions of strictly controlled ambient humidity, using an organic or inorganic solvent that does not react with the core but can dissolve a certain amount of lithium oxide, lithium hydroxide, lithium carbonate, or lithium bicarbonate as a solvent, dispersing the core in the above solvent to form a suspension, and then ultrasonicating or stirring the suspension so that the alkaline substances remaining on the surface of the core are fully dissolved in the solvent, and then drying the core material with a low surface residual alkali content.

[0126] As an example, the core can be dispersed in anhydrous ethanol and / or propanol solvent, placed in an ultrasonic cleaner for ultrasonic treatment to fully wash away the residual alkali on the surface of the core, and then placed in a vacuum oven for drying to obtain a core material with a low surface residual alkali content.

[0127] In a third aspect, the present application provides a positive electrode plate comprising a positive electrode current collector and a positive electrode active material layer located on at least one surface of the positive electrode current collector, wherein the positive electrode active material layer comprises a positive electrode active material and a lithium supplement, wherein the lithium supplement comprises the aforementioned lithium supplement or a lithium supplement prepared using the aforementioned method. Thus, the positive electrode plate possesses all the features and advantages of the aforementioned lithium supplement and method for preparing the lithium supplement, which will not be further elaborated here.

[0128] In some embodiments, the mass fraction of the lithium replenisher in the positive electrode active material layer is 0.1%-10%. In other embodiments, the mass fraction of the lithium replenisher in the positive electrode active material layer is 2%-5%.

[0129] As an example, the mass fraction of the lithium supplement agent in the positive electrode active material layer can be 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.1%, 1.2%, 1.5%, 1.8%, 2%, 2.1%, 2.2%, 2.5%, 2.8%, 3%, 3.1%, 3.2%, 3.5%, 3.8%, 4%, 4.1%, 4.2%, 4.5%, 4.8%, 5%, 5.1%, 5.2%, 5.5%, 5.8%, 6%, 6.1%, 6.2%, 6.5%, 6.8%, 7%, 7.1%, 7.2%, 7.5%, 7.8%, 8%, 8.1%, 8.2%, 8.5%, 8.8%, 9%, 9.1%, 9.2%, 9.5%, 9.8% or 10%.

[0130] When the mass fraction of the lithium replenisher in the positive electrode active material layer is 0.1%-10%, the positive electrode active material layer contains an appropriate amount of lithium replenisher, which can not only replenish the active lithium ion loss during the battery charging and discharging process for a long time, but also prevent the positive electrode active material in the positive electrode active material layer from being too insufficient due to the high content of the lithium replenisher, thereby causing insufficient reversible lithium insertion vacancies in the positive electrode active material layer and low energy density of the battery.

[0131] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0132] 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.).

[0133] 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.

[0134] As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. The modified compounds of the above materials may be modified by doping and / or surface coating the materials.

[0135] The battery's charge and discharge processes involve the intercalation and deintercalation of lithium, leading to different molar Li contents at different discharge states. The molar Li contents listed in this application for the positive electrode active materials refer to the initial state of the material, i.e., the state before addition. When the positive electrode active material is used in a battery system, the molar Li content will change after charge and discharge cycles.

[0136] In the list of positive electrode active materials in this application, the molar content of O is only a theoretical value. Lattice oxygen release will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0137] In some embodiments, the positive active material layer may further optionally include a binder.

[0138] As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0139] In some embodiments, the positive active material layer may further optionally include a conductive agent.

[0140] 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.

[0141] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, lithium supplement, conductive agent, binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0142] In some embodiments, the positive electrode sheet can be prepared by the following method: dispersing the positive electrode active material, conductive agent, binder and any other components in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on the positive electrode current collector, drying, cold pressing and other processes to form a positive electrode active material layer, and then spraying, secondary coating and other methods on the surface of the positive electrode active material layer to compound the lithium supplement agent with the positive electrode active material layer.

[0143] In a fourth aspect of the present application, the present application provides a battery comprising the aforementioned positive electrode sheet. Thus, the battery includes all the features and advantages of the aforementioned positive electrode sheet, which will not be elaborated here.

[0144] Typically, a battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0145] [Negative electrode]

[0146] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0147] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0148] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0149] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials include at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials include at least one of elemental tin, tin oxides, and tin alloys. 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.

[0150] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0151] 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.

[0152] 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)).

[0153] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0154] Generally, in order to meet the basic requirements of battery design, the negative electrode capacity needs to be slightly larger than the positive electrode capacity to reduce the risk of lithium plating at the negative electrode. For example, the CB value can be 1.07. CB is the negative electrode capacity divided by the positive electrode capacity. Specifically, the calculation formula for CB can be referred to as:

[0155] The area of ​​the current collector refers to the area of ​​the surface of the current collector on which the active material layer is provided; CW is the surface density of the active material layer on one side of the current collector, in mg / mm 2 ; Active material loading refers to the mass fraction of active material in the active material; the specific capacity of the negative electrode active material refers to the lithium insertion capacity of the negative electrode active material, and the specific capacity of the positive electrode active material refers to the lithium removal capacity of the positive electrode active material.

[0156] Taking the lithium supplement agent that completely releases the lithium supplement capacity during the first charge and discharge process as an example, since the active lithium ions it contains will all be released during the first cycle of charge and discharge, it is equivalent to an increase in the lithium desorption capacity of the positive electrode active material. In order to meet the demand for battery CB, it is necessary to increase the amount of negative electrode active material used in the negative electrode, select negative electrode active materials with higher specific capacity, and other changes, which will reduce the volume energy density of the battery and significantly increase the manufacturing cost.

[0157] In the present application, because the lithium supplement agent has the effect of slowly releasing the replenished lithium gram capacity, the active lithium ions in the lithium supplement agent are not completely released during the initial charge and discharge process. Under the same conditions, compared with a lithium supplement agent that completely releases the replenished lithium gram capacity during the initial charge and discharge process, the lithium supplement agent in the present application does not cause a sudden increase in the delithiation capacity of the positive electrode active material. As a result, only a very small increase, or even no increase, in the amount of negative electrode active material used in the negative electrode is required to meet the battery design requirements, effectively improving the battery's volumetric energy density and reducing manufacturing costs.

[0158] [Electrolytes]

[0159] The electrolyte conducts ions between the positive and negative electrodes. This application does not specify the type of electrolyte, and the electrolyte can be selected based on the needs. For example, the electrolyte can be liquid, gel, or solid.

[0160] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0161] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0162] In some embodiments, the solvent includes at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0163] 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.

[0164] [Isolation film]

[0165] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any porous separator with good chemical and mechanical stability can be selected.

[0166] In some embodiments, the material of the separator includes at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0167] 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.

[0168] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0169] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0170] In some embodiments, the battery outer packaging may be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the battery outer packaging may be a soft shell, such as a pouch-type soft shell. The soft shell may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0171] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG4 shows a square-structured battery cell as an example.

[0172] In some embodiments, referring to Figure 5, the outer packaging may include a shell 51 and a top cover assembly 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the top cover assembly 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell can be one or more, and those skilled in the art can select according to specific actual needs.

[0173] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0174] Figure 6 shows an example battery module 4. Referring to Figure 6 , in the battery module 4, multiple battery cells can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells can be secured using fasteners.

[0175] Optionally, the battery module 4 may further include a housing having an accommodation space, and a plurality of battery cells are accommodated in the accommodation space.

[0176] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0177] Figures 7 and 8 illustrate an example battery pack 1. Referring to Figures 7 and 8 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0178] In a fifth aspect of the present application, the present application provides an electrical device comprising the aforementioned battery. Thus, the electrical device includes all the features and advantages of the aforementioned battery, which will not be elaborated here.

[0179] Batteries, battery modules, and battery packs can be used as power sources or energy storage units for electrical devices. Electrical devices may include, but are not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships, satellites, and energy storage systems.

[0180] As an electrical device, a battery, battery module or battery pack can be selected according to its usage requirements.

[0181] Figure 9 shows an example of an electric device. This device can be a pure electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0182] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0183] The present invention will be described below by way of specific examples. It should be noted that the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Specific techniques or conditions not specified in the embodiments are described in accordance with the techniques or conditions described in the literature in this area or in accordance with product specifications. Reagents or instruments not specified in the manufacturer's description are all commercially available conventional products.

[0184] Example 1

[0185] Preparation of lithium supplements:

[0186] Lithium ferrite (Li5FeO4) was dispersed in anhydrous ethanol and placed in an ultrasonic cleaning machine for 40 minutes to fully wash away the residual alkali on the surface. It was then placed in a vacuum oven at 80°C and dried for 12 hours to obtain pretreated Li5FeO4 particles.

[0187] 9.5 g of the pretreated Li5FeO4 core particles were mixed evenly with 0.5 g of dimethylsiloxane (coating material) to obtain a mixture, and the mixture was placed in a tube furnace for heat treatment. The heat treatment included: maintaining at 300°C for 2 hours under a nitrogen atmosphere to obtain a lithium supplement.

[0188] Positive electrode preparation:

[0189] The positive electrode active material LiFePO4, the aforementioned lithium supplement, the conductive agent acetylene black, and the binder polyvinylidene fluoride are mixed in an N-methylpyrrolidone solvent (NMP) system in a weight ratio of 92.5:4.5:1:2, and are fully stirred until uniformly mixed to obtain a positive electrode slurry. The positive electrode slurry is coated on a positive electrode current collector aluminum foil, dried, and cold pressed to form a positive electrode active material layer to obtain a positive electrode sheet, wherein the surface density of the positive electrode active material layer on the surface of the positive electrode current collector is 0.337 g / 1540.25 mm 2 .

[0190] Negative electrode preparation:

[0191] The negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are mixed in a deionized water solvent system in a weight ratio of 96.5:0.7:1.8:1 and stirred until uniformly mixed to obtain a negative electrode slurry. The negative electrode slurry is coated on the negative electrode current collector copper foil, dried, and cold pressed to form a negative electrode active material layer to obtain a negative electrode sheet, wherein the surface density of the negative electrode active material layer on the surface of the negative electrode current collector is 0.174g / 1540.25mm 2 .

[0192] Preparation of electrolyte:

[0193] Ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed at a mass ratio of 50 / 50, and 1.1 mol of LiPF6 lithium salt was dissolved therein, and the molar concentration of LiPF6 was 1.1 mol / L to form an electrolyte.

[0194] Preparation of the battery:

[0195] Using polypropylene film as a separator, the positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrodes to provide insulation. The cells are then wound to form a bare cell. The bare cell is then placed in an outer packaging, injected with electrolyte, and packaged to form a battery.

[0196] The differences between Examples 2-23 and Comparative Examples 1-2 and Example 1 are shown in Table 1. In Comparative Example 1, no lithium supplement was added, and the positive electrode slurry contained the positive electrode active material LiFePO₄, the conductive agent acetylene black, and the binder polyvinylidene fluoride in a weight ratio of 97:1:2. In Comparative Example 2, the lithium supplement was uncoated Li₅FeO₄. In Examples 11-15, the mass fractions of the lithium supplement and the positive electrode active material in the positive electrode active material layer were adjusted accordingly, with the sum of the mass fractions of the lithium supplement and the positive electrode active material being 97%. The mass fractions of the conductive agent and the binder remained unchanged, similar to those in Example 1.

[0197] Table 1

[0198] The batteries in Examples 1-23 and Comparative Examples 1-2 were tested as follows: the test results are shown in Table 2.

[0199] 1. First cycle efficiency test: At 25°C, charge the battery at a constant current of 0.33C to a charge termination voltage of 3.65V, then charge it at a constant voltage of 0.05C to measure the charge capacity E. c0 , use E c0 Divide by the mass of the positive electrode active material in the battery to get the charge specific capacity. That is: Charge specific capacity (mAh / g) = 1st cycle charge capacity / mass of positive electrode active material.

[0200] Take the above charged battery and discharge it at a constant current of 0.33C to the discharge end voltage of 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.

[0201] First-cycle efficiency = first-cycle discharge specific capacity / first-cycle charge specific capacity.

[0202] 2. Battery high temperature storage performance test: Five batteries were tested in parallel for each example. Each battery was charged at a rate of 1C to a voltage of 3.65V at room temperature (25°C), and then discharged at a rate of 1C to a voltage of 2.5V. The reversible capacity was measured as E0. The battery charged at a rate of 1C to a voltage of 3.65V was placed in a 60°C oven and kept for 100 days. After that, each battery was charged at a rate of 1C to a voltage of 3.65V at room temperature (25°C), and then discharged at a rate of 1C to a voltage of 2.5V. The reversible capacity was measured and recorded as E0. n .

[0203] The capacity retention rate of the battery after storage at 60°C for 100 days is ε = E n / E0×100%

[0204] 3. Cycle performance test: The battery is charged at a rate of 0.5C to a voltage of 3.65V at room temperature of 25°C, and then discharged at a rate of 0.5C to a voltage of 2.5V. The reversible capacity is measured as E0. The above charge and discharge process is cycled 1000 times to obtain the reversible capacity and recorded as E0. n , where n=1000.

[0205] The capacity retention rate of the battery after 1000 cycles at 25°C is ε = E n / E0×100%

[0206] Table 2

[0207] The test results show that compared with batteries without adding lithium supplement agents to the positive electrode plates, the batteries in this application have better first-cycle efficiency, high-temperature storage performance and cycle life; compared with batteries with adding lithium supplement agents that are not surface-coated to the positive electrode plates, the lithium supplement agents in this application not only improve the first-cycle efficiency of the battery, but also utilize a specific coating layer structure to consume water and acidic substances inside the lithium supplement agent battery, thereby greatly improving the high-temperature storage performance and cycle life of the battery, achieving a long-term lithium supplement effect.

[0208] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A lithium supplement, wherein: include: A core comprising Li a M b O c , wherein a is 2-6, b is 0-4, c is 1-6, and M includes at least one of Mg, Al, Si, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, and Sn; The coating layer at least covers a portion of the surface of the core, and the coating layer contains at least one of silazane compounds, siloxane compounds, sulfonic acid silane compounds, and carbodiimide compounds.

2. The lithium supplement according to claim 1, wherein The coating layer satisfies at least one of the following conditions: (1) The silazane compound satisfies Formula 1: Wherein, R1 and R2 are independently C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl; (2) The siloxane compound satisfies Formula 2: Wherein, R3 is C1-C4 alkyl, C1-C4 fluoroalkyl, C3-C4 cycloalkyl, C3-C4 fluorocycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl; (3) The sulfonic acid silane compound satisfies Formula 3: Wherein, R4 is F, C1-C4 alkyl, C1-C4 fluoroalkyl, C2-C4 alkenyl, C2-C4 alkynyl, C6-C8 phenyl or C2-C4 cyano-substituted alkyl; (4) The carbodiimide compound satisfies Formula 4: Wherein, R5 and R6 are independently C1-C6 alkyl, C3-C4 cycloalkyl, C2-C4 alkenyl or C2-C4 alkynyl.

3. The lithium supplement according to claim 1 or 2, wherein: The coating layer satisfies at least one of the following conditions: (1) The silazane compound includes at least one of vinylsilazane and hexamethyldisilazane; (2) The siloxane compound includes at least one of dimethylsiloxane and vinylsiloxane; (3) The sulfonic acid silane compound includes at least one of trimethyl sulfonic acid silane, trimethyl p-toluene sulfonic acid silane, and trimethyl propylene sulfonic acid silane; (4) The carbodiimide compound includes at least one of N,N'-diisopropylcarbodiimide, dicyclohexylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide.

4. The lithium supplement according to any one of claims 1 to 3, wherein: The mass fraction of the coating layer in the lithium supplement agent is 2%-8%.

5. The lithium supplement according to claim 4, wherein: The mass fraction of the coating layer in the lithium supplement is 3.3%-4.5%.

6. The lithium supplement according to any one of claims 1 to 5, wherein: The coating layer has a thickness of 0.3 μm-3 μm.

7. The lithium supplement according to claim 6, wherein: The coating layer has a thickness of 0.5 μm-1 μm.

8. The lithium supplement according to any one of claims 1 to 7, wherein: The core further comprises Li2M1O2, wherein M1 comprises at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or, The core includes Li2M2O3, wherein M2 includes at least one of Ni, Co, Mn, Fe, Mo, Sn, Cr, Zr, Si, Cu, and Ru; and / or, The core includes Li2M3O4, wherein M3 includes at least one of Ni, Co, Mn, Fe, Cu, Sn, Cr, V, and Nb; and / or, The core includes Li3M4O4, wherein M4 includes at least one of Ni, Mn, Fe, Mo, Cu, Cr, Zn, Sn, Mg, and Ca; and / or, The core includes Li5M5O4, wherein M5 includes at least one of Ni, Co, Mn, Fe, Mo, Cu, Sn, Cr, and Al; and / or, The core includes Li5M6O6, wherein M6 includes at least one of Ni, Cu, Mn, Fe, Cr, Mo, Zn, Sn, Mg, and Ca; and / or, The core includes Li6M7O4, wherein M7 includes at least one of Ni, Co, Mn, Fe, Cu, and Ru.

9. The lithium supplement according to any one of claims 1 to 8, wherein: The Dv50 particle size of the inner core is 2 μm-10 μm.

10. The lithium supplement according to claim 9, wherein: The Dv50 particle size of the inner core is 3 μm-7 μm.

11. A method for preparing the lithium supplement according to any one of claims 1 to 10, wherein: include: The core is mixed with a compound containing at least one of a silicon-oxygen bond, a silicon-nitrogen bond, and an imine bond to obtain a mixture, and the mixture is subjected to a heat treatment to obtain the lithium supplement.

12. The method according to claim 11, wherein: The compound includes at least one of silazane compounds, siloxane compounds, sulfonic acid silane compounds, and carbodiimide compounds.

13. The method according to claim 11 or 12, wherein: The mass fraction of the compound in the mixture is 5%-15%.

14. The method according to any one of claims 11 to 13, wherein: Before the mixing step, the method further includes: cleaning the inner core to remove residual alkali on the surface of the inner core.

15. 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, and the lithium supplement comprises the lithium supplement as described in any one of claims 1 to 10, or a lithium supplement prepared by the method as described in any one of claims 11 to 14.

16. The positive electrode sheet according to claim 15, wherein: The mass fraction of the lithium supplement in the positive electrode active material layer is 0.1%-10%.

17. A battery, wherein: Comprising the positive electrode sheet as described in claim 15 or 16.

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