Composite lithium supplementing material and preparation method therefor, positive electrode sheet, battery, and electrical apparatus

Abstract

A composite lithium supplementing material and a preparation method therefor, a positive electrode sheet, a battery, and an electrical apparatus, relating to the technical field of batteries. The composite lithium supplementing material comprises core-shell structure particles, each core-shell structure particle comprising an inner core, and a shell wrapping the outer surface of the inner core. The shell comprises a lithium supplementing agent, and the inner core comprises a reducing agent. The reducing agent comprises at least one of elemental sulfur, elemental boron, lithium sulfide, sodium sulfide and selenium disulfide. By means of forming the lithium supplementing agent and the reducing agent into core-shell structure particles, lithium supplementing efficiency is improved. The lithium supplementing agent is a shell and the reducing agent is a core. Placing the reducing agent in a lithium supplementing agent shell enables the reducing agent to better react with the lithium supplementing agent, and decreases the decomposition potential of the lithium supplementing agent; in addition, the reducing agent can also be combined with anions in the lithium supplementing agent, to generate a stable salt and avoid gas generation. Furthermore, the reducing agent is coated inside the lithium supplementing agent, which can prevent side reactions caused by direct contact between the reducing agent and the electrolyte.

Description

Composite lithium supplement material and preparation method thereof, positive electrode sheet, battery and electrical device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on March 22, 2024, with application number 202410338767.9 and invention name “Composite lithium supplement material and preparation method thereof, positive electrode sheet, battery and electrical device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a composite lithium supplement material and a preparation method thereof, a positive electrode sheet, a battery, and an electrical device. Background Art

[0003] Lithium-ion batteries are widely used due to their high energy density and long cycle life. Lithium supplements are chemical additives used in the electrolyte of lithium-ion batteries to increase battery capacity, extend battery life, and improve battery performance. These supplements typically consist of lithium salts and organic solvents, which react with lithium ions in the battery to form stable compounds, thereby promoting the battery's charge and discharge processes.

[0004] At present, the traditional composite lithium supplement is to add its components directly into the slurry. Since the proportion of the lithium supplement in the slurry is low, the proportion of each component of the lithium supplement in the slurry is even lower. During the homogenization process, the multiple components of the multi-component lithium supplement added separately will be broken up, reducing the probability of contact between the components and reducing the lithium supplement efficiency.

[0005] Application Contents

[0006] The purpose of the embodiments of the present application is to provide a composite lithium supplement material and its preparation method, a positive electrode plate, a battery and an electrical device, aiming to alleviate the problems of large gas production and high decomposition potential of existing lithium supplement agents. Technical Solutions

[0007] The technical solution adopted in the embodiment of this application is:

[0008] In a first aspect, an embodiment of the present application provides a composite lithium supplement material, comprising core-shell structure particles, wherein the core-shell structure particles include a core and a shell coated on the outer surface of the core, the shell having a microporous structure, and the shell includes a lithium supplement agent; the core includes a reducing agent, and the reducing agent is used to undergo an oxidation-reduction reaction with the lithium supplement agent.

[0009] By forming a core-shell structure between the lithium supplement and the reducing agent, they can be brought into closer contact, preventing separation during the homogenization process. This allows for better reaction between the two and improves lithium supplement efficiency. Furthermore, the reducing agent is encapsulated within the lithium supplement, minimizing direct contact between the reducing agent and the electrolyte, thereby reducing side reactions between the reducing agent and the electrolyte.

[0010] In some embodiments, the lithium supplement comprises at least one of lithium metasilicate, lithium orthosilicate, and lithium aluminate.

[0011] In some embodiments, the reducing agent includes at least one of elemental sulfur, elemental boron, and sulfide.

[0012] The lithium-containing compound acts as a lithium supplement and can react chemically with the reducing agent during the first charge of the battery, thereby reducing the decomposition potential of the lithium supplement. Moreover, the reducing agent can also combine with the anions in the lithium supplement to form a stable salt, thereby avoiding gas generation.

[0013] In some embodiments, the mass ratio of the lithium supplement agent to the reducing agent is 1.8 to 20. In this way, the composite lithium supplement material can better exert its capacity.

[0014] In some embodiments, the core-shell structure particles have a Dv50 particle size of 0.5 to 10 μm. In this way, the lithium replenishment efficiency of the composite lithium replenishment material is better.

[0015] In some embodiments, the composite lithium supplement material further comprises a carbon material, and the carbon material satisfies at least one of the following conditions:

[0016] (1) The carbon material is coated on the outer surface of the core-shell structure particles;

[0017] (2) The carbon material has a three-dimensional network structure, and the core-shell structure particles are distributed in the three-dimensional network structure;

[0018] (3) The carbon material has a two-dimensional layered structure, and the core-shell structure particles are distributed in the two-dimensional layered structure.

[0019] By coating the surface of core-shell structure particles with carbon materials, or compounding the core-shell structure particles with carbon materials, the conductivity of the composite lithium replenishment material can be improved and the lithium replenishment efficiency can be increased.

[0020] In some embodiments, the carbon material accounts for 0.5-8% by weight of the composite lithium-supplementing material, thereby improving the conductivity of the composite lithium-supplementing material and increasing the lithium-supplementing efficiency.

[0021] In a second aspect, an embodiment of the present application provides a method for preparing a composite lithium-supplementing material, comprising the following steps: preparing a shell having a hollow structure, wherein the material of the shell comprises a lithium-supplementing agent; and filling the shell with the reducing agent to obtain the core-shell structure particles.

[0022] In some embodiments, preparing the shell includes the following steps: mixing a first template, a first surfactant, a first solvent, and an alkaline solution, then adding a silicon source to react, causing the silicon source to hydrolyze on the surface of the first template, and drying the product to obtain a first lithium supplement precursor; mixing the first lithium supplement precursor with a first lithium salt, and then calcining the mixture to remove the template, thereby obtaining a hollow lithium supplement, i.e., the shell. In this manner, a hollow shell of a lithium supplement can be prepared using lithium metasilicate or lithium orthosilicate.

[0023] In some embodiments, preparing the shell includes the following steps: mixing a second template, a second surfactant, a second solvent, and an acid solution; then adding an aluminum source to react, causing the aluminum source to hydrolyze on the surface of the second template; and drying the product to obtain a second lithium supplement precursor; then mixing the second lithium supplement precursor with a second lithium salt, followed by calcination to remove the template, thereby obtaining a hollow lithium supplement, i.e., the shell. In this manner, lithium aluminate can be prepared as a hollow shell for the lithium supplement.

[0024] In some embodiments, the mass ratio of the first surfactant to the first solvent is (0.5-2):100. The volume ratio of the first solvent to the silicon source is (20-40):1. The mass ratio of the first template to the silicon source is (0.5-1.5):1. The volume ratio of the alkaline solution to the silicon source is (17-30):20. The mass ratio of the first lithium salt to the silicon source is (3-6):20.

[0025] In some embodiments, the mass ratio of the second surfactant to the second solvent is (0.5-2):100; the volume ratio of the second solvent to the aluminum source is (20-40):1; the mass ratio of the second template to the aluminum source is (0.5-1.5):1; the volume ratio of the acid solution to the aluminum source is (17-30):20; and the mass ratio of the second lithium salt to the aluminum source is (5-10):20.

[0026] In some embodiments, the first template and the second template each independently include at least one of F127 block copolymer, P123 block copolymer, polystyrene microspheres, and phenolic resin microspheres.

[0027] In some embodiments, the first surfactant and the second surfactant each independently include at least one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0028] In some embodiments, the first solvent and the second solvent each independently include at least one of methanol, ethanol, ether, water, and potassium chloride solution.

[0029] In some embodiments, the alkaline solution includes at least one of aqueous ammonia, sodium hydroxide solution, and potassium hydroxide solution.

[0030] In some embodiments, the silicon source includes tetraethyl orthosilicate.

[0031] In some embodiments, the acid solution comprises at least one of ammonium formate-formic acid buffer, formic acid, acetic acid, and hydrochloric acid.

[0032] In some embodiments, the aluminum source comprises aluminum sulfate.

[0033] Different types of hollow structures can be formed by changing the solvent system and surfactant of the reaction.

[0034] In some embodiments, the first lithium salt and the second lithium salt each independently include at least one of lithium hydroxide, lithium carbonate, lithium dihydrogen phosphate, lithium hydrogen phosphate, and lithium phosphate.

[0035] In some embodiments, the step of removing the template by calcination comprises the following process conditions: a calcination temperature of 500 to 700° C. and a calcination time of 4 to 6 hours.

[0036] In some embodiments, filling the outer shell with the reducing agent comprises the following steps: reacting the reducing agent and the outer shell under heating and pressurization conditions to fill the outer shell with the reducing agent, thereby obtaining the core-shell structured particles.

[0037] In some embodiments, the heating and pressurizing process comprises the following process conditions: reacting in a hydrothermal autoclave, the reaction temperature is 130-170° C., and the reaction time is 6-24 h.

[0038] In a third aspect, an embodiment of the present application provides a method for preparing a composite lithium supplement material, comprising the following steps: before filling the reducing agent into the shell, first coating the surface of the shell with a carbon coating layer.

[0039] In some embodiments, a method for preparing a composite lithium supplement material includes the following steps: after filling the reducing agent into the shell, coating the surface of the shell with a carbon coating layer.

[0040] In some embodiments, a method for preparing a composite lithium supplement material includes the following steps: ball milling the core-shell structure particles and the carbon material.

[0041] The above method can prepare a core-shell structure composite lithium supplement material with a carbon material coated on the surface. Alternatively, a lithium supplement material composited with a one-dimensional carbon material or a two-dimensional carbon material can also be prepared.

[0042] In a fourth aspect, an embodiment of the present application provides a positive electrode plate, comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode active material layer comprises the composite lithium-supplementing material described in the first aspect, or a composite lithium-supplementing material obtained by the preparation method of the composite lithium-supplementing material described in the second or third aspect. Due to the use of the composite lithium-supplementing material, the positive electrode plate has improved electrical conductivity and electrochemical activity.

[0043] In a fifth aspect, an embodiment of the present application provides a battery comprising the positive electrode sheet described in the fourth aspect. Due to the use of the positive electrode sheet described above, the battery has better cycle stability.

[0044] In a sixth aspect, an embodiment of the present application provides an electrical device comprising the battery described in the fifth aspect. By adopting the battery, the operating stability of the electrical device is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 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 embodiments or exemplary technical descriptions. 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.

[0046] FIG1 is a schematic structural diagram of a composite lithium-supplementing material according to some embodiments of the present application;

[0047] FIG2 is a schematic structural diagram of a composite lithium-supplementing material according to some embodiments of the present application;

[0048] FIG3 is a schematic structural diagram of a composite lithium-supplementing material according to some embodiments of the present application;

[0049] FIG4 is a schematic structural diagram of a composite lithium supplement material according to some embodiments of the present application;

[0050] FIG5 is a schematic cross-sectional view of a pole piece according to some embodiments of the present application;

[0051] FIG6 is a schematic structural diagram of a battery cell according to some embodiments of the present application;

[0052] FIG7 is a schematic diagram of an exploded structure of a battery cell according to some embodiments of the present application;

[0053] FIG8 is a schematic structural diagram of an electrode assembly according to some embodiments of the present application;

[0054] FIG9 is a schematic structural diagram of a vehicle according to some embodiments of the present application.

[0055] The accompanying drawings in the specific implementation manner are as follows:

[0056] 10-pole piece; 1-current collector; 2-active material layer;

[0057] 20-electrode assembly; 101-negative electrode sheet; 102-positive electrode sheet; 201-negative electrode tab; 202-positive electrode tab; 203-diaphragm;

[0058] 30-battery cell; 301-housing; 302-end cover; 303-negative electrode adapter; 304-positive electrode adapter; 305-insulating member;

[0059] 40-battery; 401-box; 4011-box body; 4012-box cover;

[0060] 50-electrical device; 501-controller; 502-motor;

[0061] 100-shell; 200-core; 300-carbon coating; 400-two-dimensional layered structure; 500-three-dimensional network structure. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit this application.

[0063] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of description and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0064] 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.

[0065] 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.

[0066] 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 groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0067] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.

[0068] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0069] During the first charging process of a lithium-ion battery, the organic electrolyte will be reduced and decomposed on the surface of the negative electrode to form a solid electrolyte interface (SEI) film. During this process, a certain amount of active lithium in the positive electrode will be irreversibly consumed, resulting in problems such as low first-cycle efficiency and poor cycle life. Therefore, it is necessary to improve the first-cycle efficiency by pre-lithiation or adding lithium supplements. This can be understood as adding lithium to the battery before the lithium battery is working to supplement lithium ions to offset the irreversible lithium loss, thereby increasing the total capacity and energy density of the battery.

[0070] Common lithium replenishment methods include positive electrode lithium replenishment and negative electrode lithium replenishment. The positive electrode lithium replenishment process is simple and can be added directly during the positive electrode slurry process. The operation is simple and does not require improvements to the existing battery system, so it is expected to be mass-produced.

[0071] However, existing lithium replenishment solutions are less than ideal. For example, some common cathode lithium replenishers have high decomposition potentials and poor conductivity. Furthermore, some lithium replenishers generate gas during decomposition, which can cause battery bulging and lead to safety concerns.

[0072] Based on this, the present invention proposes a composite lithium-supplementing material that improves lithium-supplementing efficiency by forming core-shell particles with a lithium-supplementing agent and a reducing agent. The lithium-supplementing agent is the shell, and the reducing agent is the core. Placing the reducing agent within the lithium-supplementing agent shell allows the reducing agent to react with the lithium-supplementing agent, lowering the decomposition potential of the lithium-supplementing agent. The reducing agent also combines with anions in the lithium-supplementing agent to form a stable salt, reducing gas generation. Furthermore, the reducing agent is encapsulated within the lithium-supplementing agent, preventing side reactions that may occur when the reducing agent comes into direct contact with the electrolyte.

[0073] In the first aspect, please refer to Figure 1. An embodiment of the present application provides a composite lithium supplement material, including core-shell structure particles, the core-shell structure particles including a core 200 and a shell 100 coated on the outer surface of the core 200, the shell 100 having a microporous structure, and the shell 100 includes a lithium supplement agent; the core 200 includes a reducing agent, and the reducing agent is used to undergo an oxidation-reduction reaction with the lithium supplement agent.

[0074] During the first charging of the battery, the reducing agent and the lithium supplement agent will undergo a chemical reaction, which can reduce the decomposition potential of the lithium supplement agent, thereby improving the lithium supplement efficiency. Moreover, the reaction products of the reducing agent and the lithium supplement agent are all solid substances, and no gas is generated. In the embodiment of the present application, the lithium supplement agent and the reducing agent are formed into core-shell structure particles so that the two are tightly combined. Therefore, the two will not separate during the homogenization process, thereby enabling the two to react better, thereby improving the lithium supplement efficiency. Moreover, the reducing agent is coated inside by the lithium supplement agent, which can reduce the contact between the reducing agent and the electrolyte, and reduce the inability of the reducing agent to react with the lithium supplement agent after the side reaction with the electrolyte.

[0075] In some embodiments, the lithium supplement comprises at least one of lithium metasilicate, lithium orthosilicate, and lithium aluminate.

[0076] In some embodiments, the reducing agent includes at least one of elemental sulfur, elemental boron, and a sulfide.

[0077] The above-mentioned lithium replenisher can form stable hollow particles through chemical methods. Moreover, during the first charging process of the battery, the above-mentioned lithium-containing compound as a lithium replenisher can chemically react with the above-mentioned reducing agent, thereby reducing their decomposition potential; moreover, the reducing agent can also combine with the anions in the above-mentioned lithium-containing compound to form a stable salt, reducing gas generation and affecting the battery interface.

[0078] As an example, taking elemental sulfur as the reducing agent and lithium metasilicate as the lithium supplement, the following reactions will occur during the initial charging of the battery:

[0079] S+4Li2SiO3=6Li + +4SiO2+Li2SO4.

[0080] The decomposition potential of lithium metasilicate alone is higher than 4.5V, and it will generate oxygen. After combining with a reducing agent, the decomposition potential is reduced to 3.5V. The decomposition products are silicon oxide and lithium sulfate, both of which are solid substances, and no gas is generated.

[0081] As an example, taking boron as the reducing agent and lithium orthosilicate as the lithium supplement, the following reactions will occur during the initial charging of the battery:

[0082] B+Li4SiO4=3Li + +SiO2+LiBO2.

[0083] In some embodiments, the mass ratio of the lithium supplement agent to the reducing agent is 1.8-20.

[0084] As an example, the mass ratio of the lithium supplement agent to the reducing agent can be 1.8, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, etc., which are typical but non-limiting values.

[0085] By controlling the mass ratio of the lithium-supplementing agent to the reducing agent within the above range, the overall gram capacity of the composite lithium-supplementing material can be adjusted, allowing the composite lithium-supplementing material to better utilize its capacity. Excessive addition of the reducing agent will result in a decrease in the overall gram capacity of the lithium-supplementing material, while too little will hinder the full utilization of the capacity of the lithium-supplementing agent.

[0086] In some embodiments, the core-shell structured particles have a Dv50 particle size of 0.5 to 10 μm.

[0087] Dv50 is used to describe the particle size distribution of a material. It indicates the particle size value when the total particle count in a sample reaches 50%. Usually it means that the powder ions larger and smaller than this particle size each account for 50%.

[0088] As an example, the Dv50 particle size of the core-shell structured particles can be typical but non-limiting values ​​such as 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, and 10 μm.

[0089] The particle size of the core-shell structure particles affects the contact area of ​​the particles. By controlling the particle size of the core-shell structure particles within the above range, the contact area between the particles can be better increased, the composite lithium replenishment material can be better involved in the reaction, and the lithium replenishment efficiency can be improved.

[0090] In some embodiments, the composite lithium supplement material further comprises a carbon material, and the carbon material satisfies at least one of the following conditions:

[0091] (1) Carbon material is coated on the outer surface of the core-shell structure particles;

[0092] (2) The carbon material has a three-dimensional network structure, and the core-shell structure particles are distributed in the three-dimensional network structure;

[0093] (3) Carbon materials have a two-dimensional layered structure, and core-shell structure particles are distributed in the two-dimensional layered structure.

[0094] Any one of the three conditions above, or any two or all three can be met.

[0095] As an example, referring to FIG. 2 , when the core-shell structure particles are composited with carbon materials such as an organic carbon source through sintering, the outer layer of the core-shell structure particles is coated with a carbon coating layer 300 .

[0096] As an example, referring to FIG. 3 , when core-shell structured particles are compounded with carbon materials such as two-dimensional graphene, the core-shell structured particles are distributed in a two-dimensional layered structure 400 .

[0097] As an example, referring to FIG. 4 , when the core-shell structured particles are compounded with carbon materials such as one-dimensional carbon nanotubes, the core-shell structured particles are distributed in a three-dimensional network structure formed between the three-dimensional network structures 500 .

[0098] The carbon coating layer 300 may be obtained by sintering a carbon source, and the carbon source may include glucose, starch, sucrose, polyethylene glycol, polyvinyl alcohol, etc., which are not specifically limited here.

[0099] The two-dimensional layered structure 400 may be made of graphene.

[0100] The three-dimensional network structure 500 can be made of materials such as carbon nanotubes and carbon fibers.

[0101] Because carbon materials have excellent electrical conductivity, they can further enhance the conductivity of lithium supplements. Furthermore, the carbon material layer structure is stable, which helps improve the stability of core-shell particles. In the embodiments of the present application, by coating the core-shell particles with carbon materials, or by combining the core-shell particles with carbon materials, the conductivity of the composite lithium supplement material can be improved, thereby increasing the efficiency of lithium supplementation.

[0102] In some embodiments, the composite lithium supplement material includes core-shell particles and a carbon coating layer coated on the outer surface of the core-shell particles. Coating the carbon coating layer on the outer surface of the core-shell particles can better improve the conductivity of the lithium supplement material and increase the lithium supplement efficiency.

[0103] In some embodiments, the mass proportion of the carbon material in the composite lithium-supplementing material is 0.5-8%.

[0104] As an example, the mass percentage of the carbon material in the composite lithium-supplementing material can be typical but non-limiting values ​​such as 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, and 8%. By controlling the mass percentage of the carbon material in the composite lithium-supplementing material within the above range, the conductivity of the composite lithium-supplementing material can be better improved, thereby increasing the lithium-supplementing efficiency.

[0105] In a second aspect, the present invention provides a method for preparing a composite lithium-supplementing material, comprising the following steps:

[0106] S1: preparing a shell with a hollow structure, wherein the shell material includes a lithium supplement;

[0107] S2: Filling the outer shell with a reducing agent to obtain core-shell structured particles.

[0108] In some embodiments, the preparation of the shell in step S1 comprises the following steps: mixing a first template, a first surfactant, a first solvent, and an alkaline solution, then adding a silicon source to react, hydrolyzing the silicon source on the surface of the first template, and drying the product to obtain a lithium supplement precursor;

[0109] In some embodiments, a lithium supplement precursor can be prepared by a template method: a first template and a first surfactant are dispersed in a first solvent, an alkali solution is added after uniform dispersion, a silicon source is added after stirring, the mixture is filtered after stirring for a period of time, washed with deionized water and dried to obtain a first lithium supplement precursor.

[0110] As an example, 6 g of hexadecyltrimethylammonium bromide and 20 g of polystyrene microspheres can be weighed and dispersed in a 600 mm alcohol-water mixed solution at room temperature, where the mixing ratio of alcohol to water in the alcohol-water mixed solution is 1:1. After stirring and dispersing evenly, 20 ml of 28 wt% ammonia water is added, and stirring is continued for 10 minutes. 20 ml of tetraethyl orthosilicate is added, and the mixture is stirred at room temperature for 3 hours, filtered, washed with deionized water, and dried to obtain a lithium supplement agent precursor.

[0111] In some embodiments, the mass ratio of the first surfactant to the first solvent is (0.5-2): 100. As an example, the mass ratio of the first surfactant to the first solvent can be typical but non-limiting values ​​such as 0.5:100, 1:100, 1.5:100, and 2:100.

[0112] In some embodiments, the volume ratio of the first solvent to the silicon source is (20-40): 1. As an example, the volume ratio of the first solvent to the silicon source can be 20:1, 25:1, 30:1, 35:1, 40:1, and other typical but non-limiting values.

[0113] In some embodiments, the mass ratio of the first template to the silicon source is (0.5-1.5): 1. As an example, the mass ratio of the first template to the silicon source can be typical but non-limiting values ​​such as 0.5:1, 0.8:1, 1:1, 1.3:1, and 1.5:1.

[0114] In some embodiments, the volume ratio of the alkali solution to the silicon source is (17-30): 20. As an example, the mass ratio of the first template to the silicon source can be 17:20, 20:20, 25:20, 30:20, and other typical but non-limiting values.

[0115] In some embodiments, the first templating agent may include at least one of F127 block copolymer, P123 block copolymer, polystyrene microspheres, and phenolic resin microspheres.

[0116] In some embodiments, the first surfactant may include at least one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0117] In some embodiments, the first solvent may include at least one of methanol, ethanol, ether, water, and potassium chloride solution.

[0118] In some embodiments, the alkali solution may include at least one of aqueous ammonia, sodium hydroxide solution, and potassium hydroxide solution; and the silicon source may include tetraethyl orthosilicate.

[0119] Different types of hollow structures can be formed by changing the reaction solvent system and surfactant. For example, flower-like silica can be formed by adding cetyltrimethylammonium bromide (CTAB) surfactant to an ether / water mixed solvent; tubular silica can be formed by acidic hydrolysis of tetraethyl orthosilicate (TEOS) in a KCl solution system using F127 block copolymer as a template; carambola-shaped hollow silica can be synthesized using RF resin spheres (phenolic resin microspheres) as a hard template and CTAB as a surfactant; rod-shaped hollow silica can be synthesized under acidic conditions using cetyltrimethylammonium chloride (CTAC) as a surfactant; and olive-shaped hollow silica can be synthesized hydrothermally using P123 block copolymer as a template.

[0120] The shape of the core-shell structure includes but is not limited to spherical, polyhedral, carambola-shaped, spindle-shaped, etc., which can be achieved by adding different surfactants during the reaction process of generating the lithium supplement agent precursor. It can also ensure that the lithium supplement agent covers the reducing agent, ensure that the reducing agent can effectively react with the lithium supplement agent, and avoid side reactions caused by direct contact between the reducing agent and the electrolyte.

[0121] By adjusting the particle size of the template, the size of the lithium supplement precursor can be adjusted, thereby controlling the particle size of the core-shell structure particles. Generally, the size of the template is directly proportional to the particle size of the lithium supplement precursor.

[0122] In some embodiments, the first lithium supplement agent precursor is mixed with the first lithium salt, ground evenly, and then calcined to remove the template to obtain a hollow lithium supplement agent, ie, a shell.

[0123] As an example, the first lithium supplement agent precursor obtained in step S1 is evenly ground with 4.5 g of LiOH and then calcined at 600° C. for 5 h to obtain a hollow lithium supplement agent with the template removed, i.e., the shell.

[0124] In some embodiments, the amount of the first lithium salt added is calculated based on a mass ratio of the first lithium salt to the silicon source of (3-6):20. As an example, the mass ratio of the first lithium salt to the silicon source can be typical but non-limiting values ​​such as 3:20, 4:20, 5:20, and 6:20.

[0125] In some embodiments, the first lithium salt includes at least one of lithium hydroxide, lithium carbonate, lithium dihydrogen phosphate, lithium hydrogen phosphate, and lithium phosphate.

[0126] In some embodiments, the step of calcining to remove the template comprises the following process conditions: a calcination temperature of 500-700° C. and a calcination time of 4-6 hours. For example, the calcination temperature may be 500° C., 520° C., 540° C., 560° C., 580° C., 600° C., 620° C., 640° C., 660° C., 680° C., 700° C., and other typical but non-limiting values. The calcination time may be 4 hours, 4.5 hours, 5 hours, 6 hours, and other typical but non-limiting values.

[0127] S2: preparing core-shell structure particles: reacting the reducing agent and the shell under heating and pressurizing conditions so that the reducing agent is filled in the shell to obtain core-shell structure particles.

[0128] In some embodiments, the step of preparing core-shell structured particles includes: mixing a reducing agent and a lithium supplement agent (shell) in an appropriate proportion and placing them in a hydrothermal autoclave for reaction, wherein the reaction temperature is 130-170°C and the reaction time is 6-24 hours. The mixing ratio of the reducing agent and the lithium supplement agent has been described above, and the mass ratio of the lithium supplement agent to the reducing agent is controlled within the range of 1.85-19 before adding the materials. The hydrothermal autoclave generally includes components such as a high-pressure vessel, a heater, an agitator, and a temperature control device. The reducing agent and the lithium supplement agent are added to the hydrothermal autoclave, and under stirring, heating and pressurization, the reducing agent is vaporized and filled into the lithium supplement agent to form core-shell structured particles. As an example, the reaction temperature can be 130°C, 140°C, 150°C, 160°C, 170°C, etc., which are typical but non-limiting values. The reaction time can be 6 hours, 12 hours, 18 hours, 24 hours, etc., which are typical but non-limiting values.

[0129] By the preparation method provided above, core-shell structure particles can be prepared, in which lithium metasilicate or lithium orthosilicate is used as the lithium supplement agent (shell) and the reducing agent is used as the core.

[0130] In some embodiments, step S1 of preparing the shell may further include the following steps: mixing a second template, a second surfactant, a second solvent and an acid solution, then adding an aluminum source to react, so that the aluminum source is hydrolyzed on the surface of the second template, and drying the product to obtain a second lithium supplement agent precursor; mixing the second lithium supplement agent precursor with a second lithium salt, and then calcining to remove the template to obtain a hollow structure lithium supplement agent, i.e., the shell.

[0131] In some embodiments, the second lithium supplement agent precursor can be prepared by a template method: the second template and the second surfactant are dispersed in a second solvent, acid solution is added after uniform dispersion, and an aluminum source is added after stirring. The mixture is reacted at 50-80° C. for 4-8 hours and then filtered. The mixture is washed with deionized water and dried to obtain the second lithium supplement agent precursor.

[0132] As an example: 6g of hexadecyltrimethylammonium bromide (surfactant) and 20g of polystyrene microspheres with a size of 3μm (template) were weighed and dispersed in a 600mm ethanol-water mixed solution, where the volume ratio of ethanol to water in the ethanol-water mixed solution was 1:1. After uniform dispersion, ammonium formate-formic acid buffer was added, and the pH of the mixed solution was adjusted to be within the range of 4.3 to 4.5. After stirring for 10 minutes, 20mL of aluminum sulfate was added, stirred at room temperature for 3 hours, filtered, washed with deionized water, and dried to obtain a second lithium supplement agent precursor.

[0133] In some embodiments, the mass ratio of the second surfactant to the second solvent is (0.5-2):100; the volume ratio of the second solvent to the aluminum source is (20-40):1; the mass ratio of the second template to the aluminum source is (0.5-1.5):1; the volume ratio of the acid solution to the aluminum source is (17-30):20; and the mass ratio of the second lithium salt to the aluminum source is (5-10):20.

[0134] In some embodiments, the second templating agent includes at least one of F127 block copolymer, P123 block copolymer, polystyrene microspheres, and phenolic resin microspheres.

[0135] In some embodiments, the second templating agent includes at least one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride.

[0136] In some embodiments, the second solvent comprises at least one of alcohol, ether, water, and potassium chloride solution.

[0137] In some embodiments, the acid solution comprises at least one of ammonium formate-formic acid buffer, formic acid, acetic acid, and hydrochloric acid.

[0138] In some embodiments, the aluminum source includes aluminum sulfate.

[0139] Different types of hollow structures can be formed by changing the solvent system and surfactant of the reaction. The principle of preparing the second lithium supplement precursor by the template method can be referred to step 1 of the second aspect and will not be repeated here.

[0140] In some embodiments, the second lithium supplement agent precursor is mixed with the second lithium salt, and then calcined to remove the template to obtain a hollow lithium supplement agent, i.e., the shell. This method can refer to the method of step S1 of the second aspect above and will not be repeated here.

[0141] By using the preparation method provided above, core-shell structure particles can be prepared, in which lithium aluminate is used as a lithium supplement agent (shell) and a reducing agent is used as a core.

[0142] In a third aspect, an embodiment of the present application also provides a method for preparing a composite lithium-supplementing material, comprising the following steps: coating the surface of the shell with a carbon coating layer before filling the reducing agent into the shell; or coating the surface of the shell with a carbon coating layer after filling the reducing agent into the shell; or ball milling the core-shell structure particles and the carbon material.

[0143] As an example, before the step of filling the reducing agent into the shell, the method of coating the surface of the shell with a carbon coating layer includes the following steps:

[0144] Step 1: Prepare a shell according to the method described in the second aspect or the third aspect.

[0145] Step 2: After ball milling the shell and the carbon source, sintering is performed under an inert atmosphere to obtain a carbon material composite shell.

[0146] In some embodiments, the method of step 2 is: ball milling the shell (lithium supplement) and the carbon source, the carbon source includes an organic carbon source, an inorganic carbon source, carbon nanotubes, carbon fiber, graphene, etc., which are not specifically limited here. The method and conditions of ball milling can refer to the ball milling method commonly used in the art, which are not specifically limited here. After ball milling, sintering is carried out under an inert atmosphere, and the inert atmosphere includes but does not include nitrogen, argon, etc. In some embodiments, the inert gas is nitrogen. The method and conditions of sintering can refer to the sintering method commonly used in the art, and the sintering temperature and sintering time are adjusted according to the types of lithium supplement and carbon source, which are not specifically limited here.

[0147] Step 3: reacting the shell composited with the carbon material and the reducing agent under heating and pressurizing conditions to fill the shell with the reducing agent.

[0148] In some embodiments, the method of step 3 can refer to the method of step S2 of the second aspect described above, and will not be repeated here.

[0149] The core-shell structured particles can be composited with carbon materials through the preparation method provided in the third aspect.

[0150] In some embodiments, a method for preparing a composite lithium supplement material may further include the following steps:

[0151] Step (1): lithium silicate, a carbon source and water are mixed, and the mixture is then vacuum dried and sintered in an inert atmosphere to obtain a carbon material composite shell.

[0152] In some embodiments, lithium silicate and a carbon source are dissolved in water. The carbon source includes glucose, sucrose, polyethylene glycol, starch, cellulose, etc. The mixture is stirred at 80-100°C. When the mixture becomes a gel, the gel is vacuum dried. The method and conditions of vacuum drying can refer to the vacuum drying treatment method commonly used in the art and are not specifically limited here. After vacuum drying, sintering treatment is carried out under an inert atmosphere. The inert atmosphere includes but does not include nitrogen, argon, etc. In some embodiments, the inert gas is nitrogen. The method and conditions of sintering treatment can refer to the sintering treatment method commonly used in the art. The sintering temperature and sintering time are adjusted according to the type of carbon source and are not specifically limited here.

[0153] As an example: dissolve lithium silicate and glucose in water, place in a water bath at 90°C and stir continuously, wait until the water evaporates to a certain extent and the remaining substance is in a gelatinous state, transfer the gelatinous substance to a vacuum oven, vacuum bake at 60°C for 24 hours, and then transfer the remaining substance to an atmosphere furnace for sintering under a nitrogen atmosphere.

[0154] Step (2): reacting the carbon material composite shell with a reducing agent under heating and pressurizing conditions, so that the reducing agent is filled in the shell, thereby obtaining the product.

[0155] In some embodiments, the method of step (2) can refer to the method of step S2 of the second aspect described above, and will not be repeated here.

[0156] In a fourth aspect, an embodiment of the present application provides a positive electrode plate, which includes a positive electrode collector and a positive electrode active material layer arranged on the surface of at least one side of the positive electrode collector, and the positive electrode active material layer includes the composite lithium supplement material as described in the first aspect, or the composite lithium supplement material obtained by the preparation method of the second aspect or the third aspect.

[0157] Since the positive electrode plate adopts the aforementioned composite lithium supplement material, the positive electrode plate has better conductivity and electrochemical activity.

[0158] Please refer to Figure 5, which is a schematic diagram of the structure of a pole piece 10 in some embodiments of the present application. The pole piece 10 includes a current collector 1 and an active material layer 2, wherein the active material layer 2 is disposed on at least one side of the current collector 1.

[0159] The current collector 1 refers to a component used to gather current. The current collector 1 can be a negative electrode current collector or a positive electrode current collector depending on the application. When the current collector 1 is a negative electrode current collector, the active material layer 2 coated on the negative electrode current collector is a negative electrode material layer, and the resulting electrode sheet 10 is a negative electrode electrode sheet; when the current collector 1 is a positive electrode current collector, the active material layer 2 coated on the positive electrode current collector is a positive electrode material layer, and the resulting electrode sheet 10 is a positive electrode electrode sheet. Taking lithium-ion batteries as an example, optionally, the negative electrode current collector is copper foil and the positive electrode current collector is aluminum foil. In addition, the current collector 1 can be in various shapes, such as strips or squares, which are not limited here.

[0160] Active material layer 2 includes active material, a conductive agent, and a binder. Active material refers to a material that participates in electrochemical oxidation / reduction reactions. Optionally, the active material is a powder. When active material layer 2 is a negative electrode material layer, the active material is a negative electrode material. When active material layer 2 is a positive electrode material layer, the active material is a positive electrode material. Taking lithium-ion batteries as an example, the negative electrode material can be silicon and / or silicon oxides; the positive electrode material can be, but is not limited to, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium-rich manganese-based materials, etc. The conductive agent refers to a material that collects microcurrents between the active materials and between the active materials and the current collector 1. The conductive agent can be, but is not limited to, conductive graphite, carbon nanotubes, acetylene black, etc. The binder binds the active materials together to enhance electronic contact between the active material and the conductive agent, and between the active material and the current collector 1. The binder may be, but is not limited to, styrene-butadiene rubber (SBR), acrylonitrile, acrylate, polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and the like.

[0161] The current collector 1 has a first surface and a second surface that are opposite to each other along the thickness direction of the current collector 1. At least one side of the current collector 1 includes the first surface and / or the second surface of the current collector 1. It is understood that the active material layer 2 can be provided on the first surface, the second surface, or both the first surface and the second surface.

[0162] In a fifth aspect, an embodiment of the present application provides a battery comprising the positive electrode sheet described in the fourth aspect. Since the battery employs the positive electrode sheet, the battery has better cycle stability.

[0163] Please refer to Figure 6, which is a schematic diagram of the structure of a battery 40 provided in some embodiments of the present application. The battery 40 includes a housing 401 and a battery cell 30, with the battery cell 30 housed within the housing 401. The housing 401 is used to provide a space for the battery cell 30 and can adopt a variety of structures.

[0164] In some embodiments, the box body 401 may include a box body 4011 and a box cover 4012, which cover each other and together define a storage space for accommodating the battery cells 30. Alternatively, the box body 4011 may be a hollow structure with one end open, and the box cover 4012 may be a plate-like structure that covers the open side of the box body 4011.

[0165] In the battery 40, there can be multiple battery cells 30, and the multiple battery cells 30 can be connected in series, in parallel, or in a mixed connection. Mixed connection means that the multiple battery cells 30 are both connected in series and in parallel. The multiple battery cells 30 can be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple battery cells 30 is accommodated in the box 401; of course, the battery 40 can also be a battery module formed by first connecting multiple battery cells 30 in series, in parallel, or in a mixed connection, and the multiple battery modules are then connected in series, in parallel, or in a mixed connection to form a whole, and accommodated in the box 401. The battery 40 may also include other structures, such as a busbar component (not shown), for achieving electrical connection between the multiple battery cells 30.

[0166] The battery cell 30 may be a secondary battery or a primary battery, a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 30 may be cylindrical, flat, rectangular, or in other shapes.

[0167] Please refer to Figure 7, which is an exploded view of a battery cell 30 in some embodiments of the present application. A battery cell 30 is the smallest unit that makes up a battery. As shown in Figure 7, a battery cell 30 includes a housing 301, an end cap 302, an electrode assembly 20, and other functional components.

[0168] The shell 301 is a hollow structure with one end open. The shell 301 is used to cooperate with the end cap 302 to form an internal environment for accommodating the electrode assembly 20, the electrolyte and other functional components. The shell 301 can be of various shapes and sizes, such as a rectangular parallelepiped, a cylindrical shape, a hexagonal prism, etc. Specifically, the shape of the shell 301 can be determined according to the specific shape and size of the electrode assembly 20. The material of the shell 301 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here.

[0169] The end cap 302 refers to a component that covers the opening of the shell 301 to isolate the internal environment of the battery cell 30 from the external environment. Optionally, the shape of the end cap 302 can be adapted to the shape of the shell 301 to match the shell 301. Optionally, the end cap 302 can be made of a material with a certain hardness and strength (such as aluminum alloy). In this way, the end cap 302 is not easily deformed when squeezed or collided, so that the battery cell 30 can have a higher structural strength and improved safety performance. The material of the end cap 302 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., and is not limited here.

[0170] One or more electrode assemblies 20 may be contained within the housing 301 .

[0171] In some embodiments, the battery cell 30 further includes functional components such as a negative electrode adapter 303 and a positive electrode adapter 304. The negative electrode adapter 303 is used to electrically connect to the negative electrode tab on the electrode assembly 20, and the positive electrode adapter 304 is used to electrically connect to the positive electrode tab on the electrode assembly 20 to output or input electrical energy to the battery cell 30. It is understood that the negative electrode adapter 303 is made of a conductive material, and the material of the negative electrode adapter 303 can be, but is not limited to, copper, iron, aluminum, etc. The positive electrode adapter 304 is made of a conductive material, and the material of the positive electrode adapter 304 can be, but is not limited to, copper, iron, aluminum, etc.

[0172] In some embodiments, the battery cell 30 further includes an insulating member 305 located inside the housing 301 to isolate the housing 301 from the electrode assembly 20 and reduce the risk of short circuits. For example, the insulating member 305 may be made of plastic, rubber, or the like.

[0173] Please refer to Figure 8, which is a schematic diagram of the structure of the electrode assembly 20 in some embodiments of the present application. The electrode assembly 20 is the component in the battery cell 30 where the electrochemical reaction occurs. The electrode assembly 20 is primarily formed by winding or stacking a negative electrode sheet 101 and a positive electrode sheet 102 into an integrated electrode sheet structure, and a separator 203 is typically provided between adjacent negative electrode sheets 101 and positive electrode sheets 102.

[0174] The negative electrode sheet 101 includes a negative electrode current collector and a negative electrode material layer, which is coated on the surface of the negative electrode current collector. Taking a lithium-ion battery as an example, the negative electrode current collector can be made of copper, and the negative electrode material layer includes a negative electrode material, which can be a silicon-based material.

[0175] The positive electrode sheet 102 includes a positive electrode current collector and a positive electrode material layer, which is coated on the surface of the positive electrode current collector. Taking a lithium-ion battery as an example, the positive electrode current collector can be made of aluminum, and the positive electrode material layer includes a positive electrode material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganese oxide.

[0176] The separator 203 is a porous plastic film that allows lithium ions in the electrolyte to pass freely, but separates the negative electrode 101 from the positive electrode 102, preventing electrons from freely passing through the battery. The separator 203 can be made of materials such as PP (polypropylene) or PE (polyethylene).

[0177] The negative electrode current collector and the positive electrode current collector also have portions that are not coated with the active material layer. These portions without the active material layer are provided with connecting tabs. Specifically, the negative electrode current collector is connected to the negative electrode tab 201, and the positive electrode current collector is connected to the positive electrode tab 202. During the charge and discharge process of the battery, the positive electrode material layer and the negative electrode material layer react with the electrolyte, the tab 201 is connected to the negative electrode adapter 303, and the positive electrode tab 202 is connected to the positive electrode adapter 304 to form a current loop. Of course, in some embodiments, the portions of the negative electrode current collector and the positive electrode current collector that are not coated with the active material layer each constitute a tab.

[0178] In a sixth aspect, an embodiment of the present application provides an electrical device comprising the battery described in aspect 5. Since the electrical device employs the aforementioned battery, the operating stability of the electrical device is improved.

[0179] The batteries disclosed in some embodiments of the present application may be used, but are not limited to, in electrical devices such as vehicles, ships, or aircraft. A power supply system comprising the batteries disclosed in the present application may be used to form the electrical device.

[0180] For the convenience of description, the following embodiments are described by taking a vehicle 50 as an example of an electrical device according to an embodiment of the present application.

[0181] Please refer to Figure 9, which is a schematic diagram of the structure of a vehicle 50 provided in some embodiments of the present application. A battery 40 is provided inside the vehicle 50. The battery 40 can be located at the bottom, head, or tail of the vehicle 50. The battery 40 can be used to power the vehicle 50. For example, the battery 40 can serve as an operating power source for the vehicle 50. The vehicle 50 may also include a controller 501 and a motor 502. The controller 501 is used to control the battery 40 to power the motor 502, for example, to meet the power requirements of the vehicle 50 during startup, navigation, and driving.

[0182] In some embodiments of the present application, the battery 40 can serve not only as an operating power source for the vehicle 50 , but also as a driving power source for the vehicle 50 , replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 50 .

[0183] In some embodiments of the present application, the battery 40 is a secondary battery, which has various forms, including but not limited to battery cells, battery modules, and battery packs. A secondary battery here refers to a battery that can be recharged to activate the active material after discharge and continue to be used.

[0184] The following describes the details in conjunction with specific embodiments.

[0185] Example 1

[0186] (1) Preparation of composite lithium supplement materials

[0187] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0188] S1: Preparation of lithium supplement precursor:

[0189] 6 g of hexadecyltrimethylammonium bromide (surfactant) and 20 g of 3 μm polystyrene microspheres (template) were weighed and dispersed in a 600 mm ethanol-water mixture, where the volume ratio of ethanol to water was 1:1. After uniform dispersion, 20 mL of 28 wt% ammonia water was added, stirred for 10 min, and then 20 mL of tetraethyl orthosilicate was added. The mixture was stirred at room temperature for 3 h, filtered, washed with deionized water, and dried to obtain a lithium supplement precursor.

[0190] S2: Preparation of shell: The lithium supplementation agent precursor and 4.5g lithium hydroxide (LiOH) were ground evenly and then calcined at 600°C for 5h to remove the template to obtain hollow lithium metasilicate microspheres, i.e., the shell;

[0191] S3: Preparation of core-shell structure particles: 17g of shell and 3g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0192] (2) Preparation of batteries

[0193]

Preparation of positive electrode sheet

[0194] The lithium iron phosphate positive electrode active material, composite lithium supplement material, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are stirred and mixed evenly in NMP solvent in a weight ratio of 95.1:2:0.7:2.2 to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0195]

Preparation of negative electrode sheet

[0196] The active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water in a weight ratio of 96.9:0.4:1.5:1.2, and mixed evenly to prepare the negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting.

[0197] Preparation of electrolyte

[0198] In an argon atmosphere glove box (H2O<0.1ppm, O2<0.1ppm), organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed in a volume ratio of 3 / 7, 12.5% ​​LiPF6 lithium salt was added and dissolved in the organic solvent, and stirred to obtain an electrolyte.

[0199]

Isolation film

[0200] Polypropylene film is used as the isolation film.

[0201]

Battery preparation

[0202] The aforementioned positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrode sheets to provide isolation. The sheets are then wound to obtain a bare cell. The tabs are welded to the bare cell and placed in an aluminum shell. The shell is then baked at 80°C to remove moisture. The electrolyte is then injected and sealed to obtain an uncharged battery. The uncharged battery then undergoes a series of steps, including resting, hot and cold pressing, formation, shaping, and capacity testing, to obtain the lithium-ion battery product of Example 1.

[0203] Example 2

[0204] The difference between Example 2 and Example 1 is that the outer shell of the lithium orthosilicate microspheres is a hollow structure. This embodiment of the application provides a composite lithium supplement material, and the preparation method thereof includes the following steps:

[0205] S1: Preparation of lithium supplement precursor: same as Example 1.

[0206] S2: Preparation of shell: The lithium supplementation agent precursor and 8g of lithium hydroxide (LiOH) were ground evenly and then calcined at 600°C for 5h to remove the template to obtain hollow lithium orthosilicate microspheres, i.e., the shell;

[0207] S3: Preparation of core-shell structure particles: 17g of shell and 3g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0208] The preparation method of the lithium ion battery product of Example 2 is the same as that of Example 1.

[0209] Example 3

[0210] The difference between Example 3 and Example 1 is that the outer shell of the lithium aluminate microspheres is a hollow structure.

[0211] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0212] S1: Preparation of lithium supplement precursor:

[0213] 6 g of hexadecyltrimethylammonium bromide (surfactant) and 20 g of 3 μm polystyrene microspheres (template) were weighed and dispersed in a 600 mm ethanol-water mixed solution, where the volume ratio of ethanol to water in the ethanol-water mixed solution was 1:1. After uniform dispersion, ammonium formate-formic acid buffer was added, and the pH of the mixed solution was adjusted to 4.3-4.5. After stirring for 10 minutes, 20 mL of aluminum sulfate was added, and the mixture was stirred at room temperature for 3 hours. After filtering, the mixture was washed with deionized water and dried to obtain a lithium supplement precursor.

[0214] S2: Preparation of shell: The lithium supplementation agent precursor and 4.5g lithium hydroxide (LiOH) were ground evenly and calcined at 600°C for 5h to remove the template to obtain hollow lithium aluminate microspheres, i.e., the shell;

[0215] S3: Preparation of core-shell structure particles: 17g of shell and 3g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the core-shell structure particles.

[0216] The preparation method of the lithium ion battery product of Example 3 is the same as that of Example 1.

[0217] Example 4

[0218] The difference between Example 4 and Example 1 is that the reducing agent is selenium disulfide.

[0219] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0220] S1: Preparation of lithium supplement precursor: same as Example 1.

[0221] S2: Preparation of shell: same as Example 1.

[0222] S3: Preparation of core-shell structure particles: 17g of shell and 3g of selenium disulfide were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0223] The preparation method of the lithium ion battery product of Example 4 is the same as that of Example 1.

[0224] Example 5

[0225] The difference between Example 5 and Example 1 is that the mass ratio of the lithium supplement agent (shell) to the reducing agent (sulfur) is 19:1.

[0226] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0227] S1: Preparation of lithium supplement precursor: same as Example 1.

[0228] S2: Preparation of shell: same as Example 1.

[0229] S3: Preparation of core-shell structure particles: 19g of shell and 1g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0230] The preparation method of the lithium ion battery product of Example 5 is the same as that of Example 1.

[0231] Example 6

[0232] The difference between Example 6 and Example 1 is that the mass ratio of the lithium supplement agent (shell) to the reducing agent (sulfur) is 13:7.

[0233] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0234] S1: Preparation of lithium supplement precursor: same as Example 1.

[0235] S2: Preparation of shell: same as Example 1.

[0236] S3: Preparation of core-shell structure particles: 13g of shell and 7g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0237] The preparation method of the lithium ion battery product of Example 6 is the same as that of Example 1.

[0238] Example 7

[0239] The difference between Example 7 and Example 1 is that the particle size of the material is adjusted by changing the size of the template. The Dv50 particle size of the composite lithium supplementing material of this example is 0.5 μm.

[0240] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0241] S1: Preparation of lithium supplement precursor:

[0242] 6 g of hexadecyltrimethylammonium bromide (surfactant) and 20 g of 0.3 μm polystyrene microspheres (template) were weighed and dispersed in a 600 mm ethanol-water mixture, where the volume ratio of ethanol to water was 1:1. After uniform dispersion, 20 mL of 28 wt% ammonia water was added, stirred for 10 min, and then 20 mL of tetraethyl orthosilicate was added. The mixture was stirred at room temperature for 3 h, filtered, washed with deionized water, and dried to obtain a lithium supplement precursor.

[0243] S2: Same as Example 1;

[0244] S3: Same as Example 1.

[0245] The preparation method of the lithium ion battery product of Example 7 is the same as that of Example 1.

[0246] Example 8

[0247] The difference between Example 8 and Example 1 is that the particle size of the material is adjusted by changing the size of the template. The Dv50 particle size of the composite lithium supplement material of this example is 10 μm.

[0248] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0249] S1: Preparation of lithium supplement precursor:

[0250] 6 g of hexadecyltrimethylammonium bromide (surfactant) and 20 g of 6 μm polystyrene microspheres (template) were weighed and dispersed in a 600 mm ethanol-water mixture, where the volume ratio of ethanol to water was 1:1. After uniform dispersion, 20 mL of 28 wt% ammonia water was added, stirred for 10 min, and then 20 mL of tetraethyl orthosilicate was added. The mixture was stirred at room temperature for 3 h, filtered, washed with deionized water, and dried to obtain a lithium supplement precursor.

[0251] S2: Preparation of shell: same as Example 1.

[0252] S3: Preparation of core-shell structure particles: same as Example 1.

[0253] The preparation method of the lithium ion battery product of Example 8 is the same as that of Example 1.

[0254] Example 9

[0255] The difference between Example 9 and Example 1 is that the composite lithium-supplementing material of this example further includes a carbon material, and the mass proportion of the carbon material in the composite lithium-supplementing material is 4%.

[0256] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0257] S1: Preparation of lithium supplement precursor: same as Example 1.

[0258] S2: Preparation of shell: same as Example 1.

[0259] S3: Preparation of composite materials: ball-mill 17 g of shell and 0.77 g of glucose, sinter at 800 ° C for 4 h under N2 atmosphere to obtain a shell covered with a carbon coating layer; then mix it evenly with 3 g of sulfur powder and place it in a hydrothermal autoclave, and react at 150 ° C for 12 h to obtain the shell.

[0260] The preparation method of the lithium ion battery product of Example 9 is the same as that of Example 1.

[0261] Example 10

[0262] The difference between Example 10 and Example 1 is that the composite lithium-supplementing material of this example further includes a carbon material, and the mass proportion of the carbon material in the composite lithium-supplementing material is 8%.

[0263] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0264] S1: Preparation of lithium supplement precursor: same as Example 1.

[0265] S2: Preparation of shell: same as Example 1.

[0266] S3: Preparation of composite materials: ball-mill 17g of shell and 1.48g of glucose, sinter at 800℃ for 4h under N2 atmosphere to obtain a shell covered with a carbon coating layer; then mix it evenly with 3g of sulfur powder and place it in a hydrothermal autoclave, and react at 150℃ for 12h to obtain the shell.

[0267] The preparation method of the lithium ion battery product of Example 10 is the same as that of Example 1.

[0268] Example 11

[0269] The difference between Example 11 and Example 1 is that the composite lithium-supplementing material of this example further includes a carbon material, and the mass proportion of the carbon material in the composite lithium-supplementing material is 0.5%.

[0270] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0271] S1: Preparation of lithium supplement precursor: same as Example 1.

[0272] S2: Preparation of shell: same as Example 1.

[0273] S3: Preparation of composite materials: ball-mill 17 g of shell and 0.1 g of glucose, sinter at 800 ° C for 4 h under N2 atmosphere to obtain a shell covered with a carbon coating layer; then mix it evenly with 3 g of sulfur powder and place it in a hydrothermal autoclave, and react at 150 ° C for 12 h to obtain the shell.

[0274] The preparation method of the lithium ion battery product of Example 11 is the same as that of Example 1.

[0275] Example 12

[0276] The difference between Example 12 and Example 1 is that the mass ratio of the lithium supplement agent (shell) to the reducing agent (sulfur) is 12:8.

[0277] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0278] S1: Preparation of lithium supplement precursor: same as Example 1.

[0279] S2: Preparation of shell: same as Example 1.

[0280] S3: Preparation of core-shell structure particles: 12g of shell and 8g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12h to obtain the obtained particles.

[0281] The preparation method of the lithium ion battery product of Example 12 is the same as that of Example 1.

[0282] Example 13

[0283] The difference between Example 13 and Example 1 is that the mass ratio of the lithium supplement agent (shell) to the reducing agent (sulfur) is 19.2:0.8.

[0284] The present invention provides a composite lithium supplement material, and the preparation method thereof comprises the following steps:

[0285] S1: Preparation of lithium supplement precursor: same as Example 1.

[0286] S2: Preparation of shell: same as Example 1.

[0287] S3: Preparation of core-shell structure particles: 19.2 g of shell and 0.8 g of sulfur powder were mixed evenly and placed in a hydrothermal reactor, and reacted at 150°C for 12 h to obtain the obtained particles.

[0288] The preparation method of the lithium ion battery product of Example 13 is the same as that of Example 1.

[0289] Comparative Example 1

[0290] Comparative Example 1 differs from Example 1 in that the step of preparing the composite lithium supplement material is omitted. Instead, the lithium supplement agent and the reducing agent are added separately to the positive electrode slurry at a mass ratio of 17:3 to prepare the positive electrode sheet. The other steps of preparing the battery are the same as those in Example 1.

[0291] The preparation method of the positive electrode sheet of the comparative example comprises the following steps:

[0292] The lithium iron phosphate positive electrode active material, lithium metasilicate, sulfur powder, conductive agent carbon black, and binder polyvinylidene fluoride (PVDF) are stirred and mixed in NMP solvent in a weight ratio of 95.1:1.7:0.3:0.7:2.2 to obtain a positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0293] Performance Testing

[0294] In order to verify the progress of the examples of the present application, the samples of the examples and comparative examples were tested as follows:

[0295] 1. Volume average particle size DV50 test

[0296] Equipment model: Malvern 2000 (MasterSizer 2000) laser particle size analyzer, reference standard process: GB / T19077-2016 / ISO 13320:2009, specific test process: Take an appropriate amount of the sample to be tested (the sample concentration is sufficient to ensure 8-12% obscuration), add 20ml of NMP, and simultaneously ultraviolet (53KHz / 120W) for 5 minutes to ensure that the sample is completely dispersed. Then, the sample is measured according to GB / T19077-2016 / ISO 13320:2009 standard.

[0297] 2. Coating thickness test

[0298] The pre-cold-pressed electrode sheets were cut into 6cm x 6cm samples using scissors and polished using an IB-19500CP ion cross-section polisher to obtain polished samples with cut surfaces. The samples were then tested using a ZEISS Sigma 300 instrument in accordance with the JY / T010-1996 standard. Ten locations were randomly selected from the test samples for testing, and the average value was used to determine the coating thickness.

[0299] Battery performance test

[0300] 1. Battery capacity retention test

[0301] Taking Example 1 as an example, the battery capacity retention rate test process is as follows: at 25°C, the battery corresponding to Example 1 is charged to 3.65V at a constant current of 1 / 3C, then charged to a current of 0.05C at a constant voltage of 3.65V, left for 5 minutes, and then discharged to 2.5V at 1 / 3C. The obtained capacity is recorded as the initial capacity C0. Repeat the above steps for the same battery mentioned above, and at the same time record the discharge capacity Cn of the battery after the nth cycle. Then the battery capacity retention rate Pn after each cycle is Cn / C0*100%, and the battery capacity retention rate of Example 1 is obtained. In this test process, the first cycle corresponds to n=1, the second cycle corresponds to n=2, and... the 100th cycle corresponds to n=100. The battery capacity retention rate data corresponding to Example 1 in Table 1 are the data measured after 1000 cycles under the above test conditions, that is, the value of P1000. The test process of the comparative example and other embodiments is the same as above.

[0302] 2. Battery DC impedance test

[0303] Taking Example 1 as an example, the battery DC impedance test process is as follows: At 25°C, the battery corresponding to Example 1 is charged at a constant current of 1 / 3C to 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C. After 5 minutes of stagnation, the battery is discharged at a constant current of 1 / 3C for 90 minutes. After stagnation for 120 minutes, the voltage V1 is recorded. The battery is then discharged at 4C for 30 seconds, and the voltage V2 is recorded. The battery internal resistance (DCR) is calculated as (V2-V1) / 4C.

[0304] Table 1

[0305] Test results show that the battery in the present embodiment has better capacity retention and lower internal resistance than that in Comparative Example 1. The present embodiment combines a lithium replenisher and a reducing agent to form a composite lithium replenisher material with a core-shell structure, effectively improving the lithium replenishment efficiency and extending the life of the lithium-ion battery.

[0306] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A composite lithium supplement material, characterized in that: The invention comprises core-shell structure particles, wherein the core-shell structure particles include a core and a shell covering the outer surface of the core; the shell has a microporous structure; the shell includes a lithium supplement agent, the core includes a reducing agent, and the reducing agent is used to undergo an oxidation-reduction reaction with the lithium supplement agent.

2. The composite lithium supplement material according to claim 1, characterized in that The lithium supplement comprises at least one of lithium metasilicate, lithium orthosilicate and lithium aluminate.

3. The composite lithium supplement material according to claim 1 or 2, characterized in that: The reducing agent includes at least one of elemental sulfur, elemental boron, and sulfide.

4. The composite lithium supplement material according to any one of claims 1 to 3, characterized in that The mass ratio of the lithium supplement agent to the reducing agent is 1.8 to 20.

5. The composite lithium supplement material according to any one of claims 1 to 4, characterized in that The Dv50 particle size of the core-shell structure particles is 0.5 to 10 μm.

6. The composite lithium supplement material according to any one of claims 1 to 5, characterized in that The composite lithium supplement material further comprises a carbon material, and the carbon material satisfies at least one of the following conditions: (1) The carbon material is coated on the outer surface of the core-shell structure particles; (2) The carbon material has a three-dimensional network structure, and the core-shell structure particles are distributed in the three-dimensional network structure; (3) The carbon material has a two-dimensional layered structure, and the core-shell structure particles are distributed in the two-dimensional layered structure.

7. The composite lithium supplement material according to claim 6, characterized in that The carbon material accounts for 0.5-8% by mass in the composite lithium-supplementing material.

8. A method for preparing the composite lithium supplement material according to any one of claims 1 to 5, characterized in that: The following steps are involved: preparing a shell having a hollow structure, wherein the material of the shell comprises a lithium supplement; The reducing agent is filled into the outer shell to obtain the core-shell structure particles.

9. The method for preparing the composite lithium supplement material according to claim 8, characterized in that: The preparation of the shell comprises the following steps: Mixing a first surfactant, a first template, a first solvent, and an alkaline solution, then adding a silicon source to react, causing the silicon source to hydrolyze on the surface of the first template, and drying the product to obtain a first lithium supplement agent precursor; mixing the first lithium supplement agent precursor with a first lithium salt, and then calcining to remove the template to obtain the shell; Alternatively, a second template, a second surfactant, a second solvent and an acid solution are mixed, and then an aluminum source is added to react, so that the aluminum source is hydrolyzed on the surface of the second template, and the product is dried to obtain a second lithium supplement agent precursor; the second lithium supplement agent precursor is mixed with a second lithium salt, and then calcined to remove the template to obtain the shell.

10. The method for preparing the composite lithium supplement material according to claim 9, characterized in that: The mass ratio of the first surfactant to the first solvent is (0.5-2):100; the volume ratio of the first solvent to the silicon source is (20-40):1; the mass ratio of the first template to the silicon source is (0.5-1.5):1; the volume ratio of the alkali solution to the silicon source is (17-30):20; the mass ratio of the first lithium salt to the silicon source is (0.5-1.5):

1. (3-10): 20; Alternatively, the mass ratio of the second surfactant to the second solvent is (0.5-2):100; the volume ratio of the second solvent to the aluminum source is (20-40):1; the mass ratio of the second template to the aluminum source is (0.5-1.5):1; the volume ratio of the acid solution to the aluminum source is (17-30):20; and the mass ratio of the second lithium salt to the aluminum source is (5-10):

20.

11. The method for preparing a composite lithium supplement material according to claim 9 or 10, characterized in that: The first template and the second template independently include at least one of F127 block copolymer, P123 block copolymer, polystyrene microspheres, phenolic resin microspheres, and / or; The first surfactant and the second surfactant independently include at least one of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride; and / or, The first solvent and the second solvent independently include at least one of methanol, ether, water, and potassium chloride solution; and / or, The silicon source includes tetraethyl orthosilicate; and / or, The aluminum source comprises aluminum sulfate; and / or, The first lithium salt and the second lithium salt each independently include at least one of lithium hydroxide, lithium carbonate, lithium dihydrogen phosphate, lithium hydrogen phosphate and lithium phosphate.

12. The method for preparing the composite lithium supplement material according to claim 8, characterized in that: Filling the reducing agent into the shell comprises the following steps: reacting the reducing agent and the shell under heating and pressurizing conditions to fill the reducing agent into the shell, thereby obtaining the core-shell structured particles.

13. The method for preparing a composite lithium supplement material according to claim 12, wherein: The heating and pressurizing process includes the following process conditions: reacting in a hydrothermal kettle, the reaction temperature is 130-170° C., and the reaction time is 6-24 hours.

14. A method for preparing the composite lithium supplement material according to claim 6 or 7, characterized in that: The following steps are involved: Before the step of filling the reducing agent into the shell, a carbon coating layer is first coated on the surface of the shell; or, After the step of filling the shell with the reducing agent, coating the surface of the shell with a carbon coating layer; or, The core-shell structure particles and carbon material are ball-milled.

15. A positive electrode plate, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer arranged on at least one side of the positive electrode current collector, and the positive electrode active material layer includes the composite lithium supplement material according to any one of claims 1 to 7, or the composite lithium supplement material obtained by the preparation method of the composite lithium supplement material according to any one of claims 8 to 14.

16. A battery, characterized in that: Comprising the positive electrode sheet as claimed in claim 15.

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

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