CN117276508A - Composite lithium supplementing material and preparation method and application thereof - Google Patents

Composite lithium supplementing material and preparation method and application thereof Download PDF

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Publication number
CN117276508A
CN117276508A CN202311281371.7A CN202311281371A CN117276508A CN 117276508 A CN117276508 A CN 117276508A CN 202311281371 A CN202311281371 A CN 202311281371A CN 117276508 A CN117276508 A CN 117276508A
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Prior art keywords
lithium
supplementing material
supplementing
composite
lithium supplementing
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Inventor
谭旗清
万远鑫
孔令涌
裴现一男
骆文森
林律欢
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Shenzhen Dynanonic Innovazone New Energy Technology Co Ltd
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Shenzhen Dynanonic Innovazone New Energy Technology Co Ltd
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Priority to CN202311281371.7A priority Critical patent/CN117276508A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
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    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • H—ELECTRICITY
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/40—Alloys based on alkali metals
    • H01M4/405—Alloys based on lithium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
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    • H01M4/00—Electrodes
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5805—Phosphides
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    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
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    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
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    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/582—Halogenides
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    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract

The application relates to the technical field of lithium ion batteries, in particular to a composite lithium supplementing material and a preparation method and application thereof. The composite lithium supplementing material comprises a first lithium supplementing material and a second lithium supplementing material, and at least part of the second lithium supplementing material is embedded into particles of the first lithium supplementing material; the first lithium supplementing material is a lithium-rich metal oxide, the second lithium supplementing material is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material are different. The composite lithium supplementing material formed by compounding and synergy of the two lithium supplementing materials has the advantages of good structural stability, high lithium supplementing capacity and high lithium ion conductivity, and the comprehensive properties are superior to those of the existing lithium supplementing material, so that the first effect and the energy density of the prepared battery can be improved. The preparation method comprises mixing two materials to be burned, sintering in protective atmosphere, wherein the first material to be burned comprises at least one of a first lithium supplementing material and a precursor; the second to-be-burned object comprises a second lithium supplementing material.

Description

Composite lithium supplementing material and preparation method and application thereof
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a composite lithium supplementing material and a preparation method and application thereof.
Background
In the first charge and discharge process of the lithium ion battery, a large amount of solid electrolyte interface films are generated on the surface of the negative electrode of the battery, limited lithium ions and electrolyte in the battery are consumed, irreversible capacity loss is caused, the energy density of the lithium ion secondary battery is reduced, the charge and discharge efficiency of electrode materials is reduced, and the application of the lithium ion battery is limited. In the prior art, the problems can be improved by adding lithium supplementing materials to the positive electrode or the negative electrode, for example, the first irreversible capacity loss of the lithium battery can be effectively compensated by adding the lithium supplementing materials to the positive electrode materials. However, the conventional positive electrode lithium supplementing agent has poor structural stability or low lithium supplementing capacity, and can cause problems of capacity attenuation, cycle life reduction, low gram capacity and the like. Therefore, development of a lithium supplementing material having good structural stability and high lithium supplementing capacity is needed.
In order to improve structural stability and conductivity, the prior art is often improved by doping, morphology regulation, surface coating and other methods, but the large-scale industrial application of the lithium supplementing material is greatly limited due to the fact that the process steps are complex, the uniformity is limited, the improvement effect is not ideal and the like.
Disclosure of Invention
The purpose of the application is to provide a composite lithium supplementing material, a preparation method and application thereof, and aims to solve the problems of poor structural stability and low lithium supplementing capacity of the lithium supplementing material in the prior art.
In order to achieve the purposes of the application, the technical scheme adopted by the application is as follows:
in a first aspect, the present application provides a composite lithium supplementing material. The composite lithium supplementing material comprises a first lithium supplementing material and a second lithium supplementing material, and at least part of the second lithium supplementing material is embedded into particles of the first lithium supplementing material;
the first lithium supplementing material is a lithium-rich metal oxide, the second lithium supplementing material is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material are different.
The composite lithium supplementing material comprises a first lithium supplementing material and a second lithium supplementing material, wherein the first lithium supplementing material of the lithium-rich metal oxide is good in structural stability, and the second lithium supplementing material of the binary lithium-rich material is high in lithium content, so that the lithium supplementing capacity is high, the lithium ion conductivity is high, and lithium ions are easy to separate. And at least part of the second lithium supplementing material is embedded into the particles of the first lithium supplementing material, so that the two materials can be further combined tightly, and the composite lithium supplementing material formed after the two materials are compounded and enhanced has the advantages of good structural stability, low residual alkali number, high lithium supplementing capacity and high lithium ion conductivity, and the comprehensive property is superior to that of the existing lithium supplementing material.
In a second aspect, the present application provides a method of preparing a composite lithium-supplementing material. The preparation method comprises the following steps:
mixing a first to-be-burned object and a second to-be-burned object, and then sintering in a protective atmosphere to obtain a composite lithium supplementing material;
the first to-be-burned object comprises at least one of a first lithium supplementing material and a first lithium supplementing material precursor, and the first lithium supplementing material is a lithium-rich metal oxide;
the second to-be-burned object comprises a second lithium supplementing material, the second lithium supplementing material is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material are different.
According to the preparation method, the two materials to be burned are mixed and then sintered in a protective atmosphere, so that at least part of generated second lithium-supplementing material can be embedded into particles of the first lithium-supplementing material, and the first lithium-supplementing material and the second lithium-supplementing material are tightly combined, so that the prepared composite lithium-supplementing material has the advantages of good structural stability, high lithium-supplementing capacity and high lithium ion conductivity, and the comprehensive property is superior to that of the existing lithium-supplementing material. In addition, the preparation method is controllable in process, and the prepared composite lithium supplementing material is stable in physical and chemical properties.
In a third aspect, the present application provides a positive electrode. The positive electrode comprises a current collector and a positive electrode active material layer combined on the current collector, wherein the positive electrode active material layer contains the composite lithium supplementing material or the composite lithium supplementing material prepared by the preparation method.
Because this application positive pole contains this application compound benefit lithium material, therefore, this application positive pole has high benefit lithium capacity to improved the first effect and the energy density of the battery that contain this application positive pole.
In a fourth aspect, the present application provides a secondary battery. The secondary battery includes the positive electrode of the present application.
The secondary battery provided by the application has high initial efficiency and energy density due to the inclusion of the positive electrode.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following description will briefly introduce the drawings that are needed in the embodiments or the description of the prior art, it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a composite lithium-supplementing material according to an embodiment of the present application;
FIG. 2 is a schematic diagram of a composite lithium-supplementing material according to an embodiment of the present application;
FIG. 3 is a schematic diagram of a composite lithium-supplementing material according to an embodiment of the present application;
FIG. 4 is a schematic diagram of a composite lithium-supplementing material according to an embodiment of the present application;
FIG. 5 is a schematic diagram of a composite lithium-supplementing material including an encapsulation layer according to an embodiment of the present application;
FIG. 6 is an SEM image of a composite lithium-supplementing material of example A1 of the present application;
the reference numerals are as follows:
1-particles of a first lithium-compensating material; 2-a second lithium supplementing material; 3-an encapsulation layer.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved by the present application more clear, the present application is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of an association object, which means that there may be three relationships, for example, a and/or B may mean: a alone, a and B together, and B alone. Wherein A, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship.
In the present application, "at least one" means one or more, and "a plurality" means two or more. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, "at least one (individual) of a, b, or c," or "at least one (individual) of a, b, and c," may each represent: a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple, respectively.
It should be understood that, in various embodiments of the present application, the sequence number of each process does not mean that the sequence of execution is sequential, and some or all of the steps may be executed in parallel or sequentially, where the execution sequence of each process should be determined by its functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application in the examples and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The weights of the relevant components mentioned in the embodiments of the present application may refer not only to specific contents of the components, but also to the proportional relationship between the weights of the components, and thus, any ratio of the contents of the relevant components according to the embodiments of the present application may be enlarged or reduced within the scope disclosed in the embodiments of the present application. Specifically, the mass in the specification of the embodiment of the present application may be a mass unit well known in the chemical industry field such as μ g, mg, g, kg.
The terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated for distinguishing between objects such as substances from each other. For example, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX, without departing from the scope of embodiments of the present application. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature.
A first aspect of the embodiments of the present application provides a composite lithium-supplementing material, as shown in fig. 1 to 5, where the composite lithium-supplementing material includes a first lithium-supplementing material and a second lithium-supplementing material 2, and at least a portion of the second lithium-supplementing material 2 is embedded in particles 1 of the first lithium-supplementing material; the first lithium supplementing material is a lithium-rich metal oxide, the second lithium supplementing material 2 is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material 2 are different.
Lithium-rich metal oxide: the lithium-rich metal oxide has a lithium supplementing effect and high structural stability.
Binary lithium-rich material: the binary material is formed by Li and another element, and the binary material is understood in a broad sense, and the binary material is the binary material of Li and another element, which can be other elements other than lithium or other elements with similar properties, and the binary lithium-rich material is characterized by high content of lithium element, higher lithium supplementing capacity when being used as a lithium supplementing material, higher lithium ion conductivity and more favorable for lithium ion extraction.
Embedding: as shown in fig. 1, the second lithium supplementing material 2, which means a single particle, is distributed inside the particles 1 of the first lithium supplementing material; the second lithium-supplementing material 2 may be a single particle, i.e., a part of the second lithium-supplementing material is embedded in the first lithium-supplementing material 1, and a part of the second lithium-supplementing material is exposed on the surface of the first lithium-supplementing material 1.
At least in part: meaning that when the second lithium-supplementing material 2 contains a plurality of particles, at least a portion of the particles are present.
The compound lithium supplementing material of this application embodiment includes first lithium supplementing material and second lithium supplementing material 2, and wherein the first lithium supplementing material of rich lithium metal oxide structural stability is good, and the second lithium supplementing material 2 lithium content of binary rich lithium material is high, so the lithium supplementing capacity is high, and lithium ion conductivity is high, and lithium ion deviate from easily. And at least part of the second lithium supplementing material 2 is embedded into the particles 1 of the first lithium supplementing material, so that the two materials can be further combined tightly, and the composite lithium supplementing material formed after the two materials are compounded and enhanced has the advantages of good structural stability, high lithium supplementing capacity, low residual alkali number and high lithium ion conductivity, and the comprehensive property is superior to that of the existing lithium supplementing material.
Regarding the first lithium supplementing material:
in some embodiments, the chemical formula of the first lithium-supplementing material includes Li a M b O c Wherein a is more than 1 and less than or equal to 8, b is more than 0 and less than 5, c is more than 0 and less than 7, in the example, a can be 1, 2, 4, 6 and 8, b can be 1, 2, 3 and 4, and c can be 1, 2, 4 and 6; m comprises Fe, ni, mn, cu, zn, co, al, cr, zr, sb, ti,At least one of V, mo and Sn, li a M b O c May include but is not limited to Li 2 NiO 2 、Li 2 CuO 2 、Li 2 CoO 2 、Li 2 MnO 2 、Li 2 Ni 0.5 Mn 1.5 O 4 、Li 5 FeO 4 、Li 6 MnO 4 、Li 6 CoO 4 、Li 6 ZnO 4 、Li 2 Ni d Cu (1-d) O 2 Lithium-rich metal oxide such as (0 < d < 1), li a M b O c The material has high structural stability, and the composite lithium supplementing material provided by the embodiment of the application has excellent structural stability. In the composite lithium supplementing material according to the embodiment of the present application, at least one of the above-mentioned first lithium supplementing materials may be included, for example, li may be contained 2 NiO 2 、Li 2 CuO 2 Two physical mixtures or sinters.
Regarding the second lithium supplementing material 2:
in some embodiments, the chemical formula of the second lithium-supplementing material 2 includes Li x A y Wherein x is more than 0 and less than or equal to 5, y is more than 0 and less than 4, in the example, the value of x can include but is not limited to 1, 2, 3, 4 and 5, and the value of y can include but is not limited to 1, 2 and 3; a comprises at least one of P, S, F, B, O, se, N, li x A y May include but is not limited to Li 3 N、LiF、Li 2 O、Li 2 S and other binary lithium-rich materials, when Li x A y Where A is two or more elements, also in embodiments of the present application are binary lithium-rich materials, e.g., li 2 S 0.5 F 0.5 、Li 3 P 0.5 F 0.5 . Above Li x A y The lithium element content of the material is high, so that the lithium supplementing capacity is high, the lithium ion conductivity is higher, and the lithium ion extraction is facilitated. In the composite lithium supplementing material according to the embodiment of the present application, at least one of the above-described second lithium supplementing materials 2 may be included, for example, li may be contained 3 N, liF two physical mixtures or sinters.
In some embodiments, the second lithium-supplementing material 2 accounts for 0.1% -20% of the total mass of the composite lithium-supplementing material; examples may include, but are not limited to, 0.1%, 0.5%, 1%, 5%, 10%, 20%. The second lithium supplementing material with the mass ratio is beneficial to improving the synergistic effect of the first lithium supplementing material and the second lithium supplementing material 2, is beneficial to the composite lithium supplementing material to have enough lithium supplementing capacity, has lower residual alkali on the surface of the composite lithium supplementing material, and is beneficial to further improving the processing performance of the composite lithium supplementing material in the positive electrode slurry.
For the composite lithium supplementing material of the embodiment of the application:
the second lithium-supplementing material 2 may be embedded in the particles 1 of the first lithium-supplementing material in the following manner:
for example, in some embodiments, as shown in fig. 1, the second lithium-supplementing material 2 may be randomly distributed in the particles 1 of the first lithium-supplementing material, and may be uniformly distributed in the particles 1 of the first lithium-supplementing material.
For example, in some embodiments, as shown in fig. 2, in the particles 1 of the first lithium supplementing material, the content of the second lithium supplementing material 2 in the surface layer is greater than that in the interior; thus, lithium ions in the second lithium supplementing material 2 can be preferentially extracted, so that the lithium ion conductivity of the composite lithium supplementing material is improved, and the lithium supplementing effect is improved. In addition, the structural stability of the second lithium-supplementing material 2 of at least part of the binary lithium-rich materials is generally weak relative to that of the first lithium-supplementing material, a small amount of gas production phenomenon sometimes occurs along with the release of lithium ions in the lithium supplementing process of practical application, and when the surface layer content of the particles 1 of the first lithium-supplementing material is higher and the gas production phenomenon occurs in the lithium removing process, the generated gas can be discharged after the battery is charged and discharged for the first time, so that the safety in the subsequent daily use is improved.
For example, in other embodiments, as shown in fig. 2, the content of the second lithium-supplementing material 2 tends to increase along the direction from the inside to the surface of the particles 1 of the first lithium-supplementing material, and similarly, lithium ions in the second lithium-supplementing material 2 can be preferentially extracted, so as to improve the lithium ion conductivity of the composite lithium-supplementing material, improve the lithium-supplementing effect, improve the structural stability of the composite lithium-supplementing material, and improve the safety of the battery.
In some embodiments, as shown in fig. 3, the particles 1 of the first lithium-supplementing material have cracks, at least part of the second lithium-supplementing material 2 is incorporated in the cracks, and the shape of the second lithium-supplementing material 2 may be the shape of the corresponding cracks or may be a non-corresponding shape. The binding force between the particles 1 of the first lithium supplementing material and the second lithium supplementing material 2 is improved in the mode, and at least part of areas of the second lithium supplementing materials 2 are located in cracks of the particles 1 of the first lithium supplementing material, so that the surface stability of the second lithium supplementing material 2 is further improved, and the structural stability and the lithium supplementing effect of the composite lithium supplementing material are further improved.
In some embodiments, as shown in fig. 4, the particles 1 of the first lithium supplementing material include primary particles and secondary particles, the secondary particles are formed by aggregating a plurality of primary particles, gaps are formed between the plurality of primary particles, and at least part of the second lithium supplementing material 2 is filled in the gaps. The distribution mode is favorable for further combining the structural stability of the first lithium supplementing material and the lithium supplementing capacity of the second lithium supplementing material 2, and is favorable for preferential lithium removal of the second lithium supplementing material 2, so that the structural stability and the lithium supplementing capacity of the composite lithium supplementing material are further improved.
In addition to the above manner in which at least part of the second lithium-supplementing material 2 is intercalated into the particles 1 of the first lithium-supplementing material, there may be a part of the second lithium-supplementing material 2 in the following manner: in some embodiments, as shown in fig. 1 and 2, a second lithium supplementing material 2 is further combined on the surface of the particles 1 of the first lithium supplementing material. The bonding mode can be that the sintering contacts the surface of the particles 1 of the first lithium supplementing material, so that the structural stability of the composite lithium supplementing material is further improved, lithium ions in the second lithium supplementing material 2 can be preferentially separated, the lithium ion conductivity is improved, the lithium supplementing capacity is improved, and the safety of a manufactured battery is improved.
In some embodiments, the particle size of the first lithium-compensating material is greater than the particle size of the second lithium-compensating material 2 to intercalate the second lithium-compensating material 2 into the particles 1 of the first lithium-compensating material. The particle size D50 of the first lithium-supplementing material is 0.5-70 μm, and in the exemplary examples, the particle size D50 may include, but is not limited to, 0.5 μm, 2 μm, 5 μm, 10 μm, 30 μm, and 70 μm, and the first lithium-supplementing material with the particle size has good structural stability, so that the composite lithium-supplementing material has better structural stability, and in practical application, the particle sizes are favorable for dispersing in the positive electrode slurry, reducing particle agglomeration, and being favorable for electron conduction and ion conduction when used in the positive electrode, and improving the electrochemical performance of the prepared secondary battery. The particle size D50 of the second lithium-supplementing material 2 is 5-1000 nm, which may include, but is not limited to, 5nm, 10nm, 25nm, 100nm, 500nm, and 1000nm in the example, and the second lithium-supplementing material 2 with the particle size may be better inserted into the particle 1 of the first lithium-supplementing material, so as to enhance the synergistic effect of the two, and provide the composite lithium-supplementing material with better structural stability.
In some embodiments, the composite lithium-supplementing material has a particle size D50 of 0.5 to 100 μm; examples may include, but are not limited to, 0.5 μm, 5 μm, 20 μm, 50 μm, 100 μm; in some embodiments, the specific surface area of the composite lithium supplementing material is 0.5-60 m 2 /g; examples may include, but are not limited to, 0.5m 2 /g、5m 2 /g、10m 2 /g、30m 2 /g、60m 2 And/g. The particle sizes or the specific surface areas are favorable for the composite lithium supplementing material provided by the embodiment of the application to have better structural stability, and in practical application, the particle sizes are favorable for dispersing in the positive electrode slurry, reducing particle aggregation, being favorable for electronic conduction and ionic conduction during positive electrode, and improving the electrochemical performance of the prepared secondary battery.
In some embodiments, the residual alkali content of the composite lithium-supplementing material is less than or equal to 15%. It can be understood that the lower the residual alkali content of the lithium supplementing material, the better the stability in air, and the higher the residual alkali content, the easier the moisture absorption in air, and the processability is affected. According to the embodiment of the application, the binary lithium-rich material with high capacity but high residual alkali value is embedded into the lithium-rich metal oxide with good structural stability in the air, so that the structural stability of the whole composite lithium-supplementing material in the air is improved, the processing performance of the composite lithium-supplementing material in the anode slurry is improved, and meanwhile, the better lithium-supplementing capacity is considered.
In some embodiments, as shown in fig. 5, the first lithium-supplementing material and the second lithium-supplementing material 2 in the composite lithium-supplementing material of the embodiment of the present application form a core, and further include an encapsulation layer 3, where the encapsulation layer 3 encapsulates the core. According to the performance requirements or application scenes of the composite lithium-supplementing material, the packaging layers 3 can endow the composite lithium-supplementing material with better structural stability, and have the additional effects of isolating water and air, improving conductivity, improving lithium ion conductivity and the like, and can improve the electrochemical performance of the composite lithium-supplementing material. The encapsulation layer 3 may be correspondingly selected from a corresponding material, such as at least one of carbon material, oxide, carbide, nitride, sulfide, phosphate, lithium ion conductor material. The thickness of the encapsulation layer 3 may be 1 to 1000nm, and in the example, may include but not limited to 1nm, 10nm, 100nm, 500nm, 1000nm; the encapsulation layer 3 may account for 0.1% -15% of the mass of the composite lithium supplementing material, and in an exemplary embodiment, may include, but is not limited to, 0.1%, 1%, 5%, 10%, 15%. The encapsulation layer 3 with the thickness or mass ratio is beneficial to further improving the structural stability of the composite lithium supplementing material, has the additional effects of isolating water and air, improving conductivity, improving lithium ion conductivity and the like, ensures the sufficient content of the core body and ensures the sufficient lithium supplementing capacity.
The packaging layer 3 can be formed by only one layer, or two or more functional layers, and the inner and outer coating sequence of each functional layer is unlimited. For example, in some embodiments, two functional layers may be included, where one layer may be a carbon coating layer, and the other layer is a functional layer of another material, where the carbon coating layer may have a thickness of 1-500 nm, the carbon coating layer may account for 0.1-5% of the mass of the composite lithium-supplementing material, the functional layer of another material may have a thickness of 1-500 nm, and the functional layer may account for 0.1-10% of the total mass of the composite lithium-supplementing material.
In some embodiments, a second lithium-supplementing material 2 is also contained in the encapsulation layer 3. When only one layer is included in the encapsulation layer 3, the second lithium supplementing material 2 may be included in the entire encapsulation layer 3, and when two or more functional layers are included in the encapsulation layer 3, the second lithium supplementing material 2 may be included in at least one of the functional layers. When the second lithium supplementing material 2 is contained in the packaging layer 3, the lithium supplementing capacity of the composite lithium supplementing material is further improved, lithium ions in the second lithium supplementing material are preferentially removed, and the lithium supplementing effect is improved.
Finally, the composite lithium supplementing material prepared in the embodiment of the application can be used together with at least one of the first lithium supplementing material, the first lithium supplementing material containing the packaging layer 3, the second lithium supplementing material 2 and the second lithium supplementing material 2 containing the packaging layer 3 in practical application, so as to improve the lithium supplementing effect.
A second aspect of the embodiments of the present application provides a method for preparing a composite lithium supplementing material, including the following steps:
s10, mixing the first to-be-burned object and the second to-be-burned object, and then sintering in a protective atmosphere to obtain the composite lithium supplementing material;
the first to-be-burned object comprises at least one of a first lithium supplementing material 2 and a first lithium supplementing material precursor, and the first lithium supplementing material is a lithium-rich metal oxide;
the second to-be-burned object comprises a second lithium supplementing material 2, the second lithium supplementing material 2 is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material 2 are different.
According to the preparation method, the two materials to be burned are mixed and then sintered in a protective atmosphere, so that the two materials to be burned in the sintering process can respectively form the first lithium-supplementing material and the molten second lithium-supplementing material 2, at least part of the second lithium-supplementing material 2 can be embedded into the particles 1 of the first lithium-supplementing material, the first lithium-supplementing material and the second lithium-supplementing material 2 obtained by the sintering process are tightly combined, and the composite lithium-supplementing material formed after the compounding and the synergism has the advantages of good structural stability, high lithium-supplementing capacity and high lithium ion conductivity, and the comprehensive property is superior to that of the existing lithium-supplementing material. The preparation method of the embodiment of the application has controllable process, and the prepared composite lithium supplementing material has stable physical and chemical properties.
Step S10:
a first object to be burned:
comprises at least one of a first lithium supplementing material and a first lithium supplementing material precursor, a lithium-rich metal oxide of the first lithium supplementing material and Li a M b O c The details of the description can be found in the present inventionApplication examples description in composite lithium supplementing materials.
The preparation method of the first lithium supplementing material precursor can be that a lithium source and an M source are uniformly mixed according to the molar ratio in the chemical formula of the lithium-rich metal oxide, for example, ball milling can be carried out under vacuum or inert atmosphere, and the lithium source can comprise at least one of lithium hydroxide, lithium carbonate, lithium oxalate and lithium oxide; the M source may include at least one of a hydroxide, an oxide, a nitrate, a carbonate, a sulfate, a chloride of the transition metal M. When the composite lithium supplementing material needs to be prepared to contain the first lithium supplementing materials with various chemical formulas, corresponding first lithium supplementing material precursors can be prepared respectively, and finally, mixing is carried out.
The first lithium supplementing material may be a first lithium supplementing material of the above corresponding chemical formula, and the preparation method may be to sinter the precursor of the first lithium supplementing material in a protective atmosphere at 500-900 ℃ for 5-24 hours, in the example, the temperature may include but not limited to 500 ℃, 600 ℃, 650 ℃, 700 ℃, 800 ℃, 900 ℃ and the time may include but not limited to 5 hours, 9 hours, 13 hours, 18 hours and 24 hours. And sintering the first lithium supplementing material precursor into the corresponding first lithium supplementing material at the temperatures and for the times. When the composite lithium supplementing material needs to be prepared to contain the first lithium supplementing materials with various chemical formulas, the corresponding first lithium supplementing materials can be prepared respectively, and finally, the first lithium supplementing materials are mixed.
The first to-be-fired material includes at least one of the first lithium-supplementing material precursor and the first lithium-supplementing material, so that only the first lithium-supplementing material precursor, only the first lithium-supplementing material or both may be used. The first lithium supplementing material precursors or the first lithium supplementing materials are favorable for the first lithium supplementing materials contained in the composite lithium supplementing materials prepared by the subsequent preparation method, so that the prepared composite lithium supplementing materials have better structural stability.
And (3) a second to-be-burned object:
comprises a second lithium supplementing material 2, wherein the second lithium supplementing material 2 is a binary lithium-rich material, a binary lithium-rich material and Li x A y For details, see the description of the composite lithium supplementing material in the examples of the present application. The binary lithium-rich materials are beneficial to subsequent preparation methodsThe prepared composite lithium supplementing material contains the second lithium supplementing material 2, so that the prepared composite lithium supplementing material has higher content of lithium elements, and the lithium supplementing capacity is improved.
The mass ratio of the first to-be-burned object to the second to-be-burned object is 80:20 to 99.9:0.1, and in the exemplary example may include, but is not limited to, 80: 20. 85: 15. 90: 10. 92: 8. 95: 5. 97: 3. 98: 2. 99.9:0.1; the first to-be-fired object and the second to-be-fired object with the mass ratios are beneficial to controlling the mass ratio of the first lithium supplementing material to the second lithium supplementing material 2 in the prepared composite lithium supplementing material, and are beneficial to improving the structural stability, the lithium supplementing capacity and the lithium ion conductivity of the prepared composite lithium supplementing material.
The sintering process may be performed at 500-900 c for 3-24 h, and in an exemplary embodiment, the sintering process may be performed at 500 c, 600 c, 700 c, 800 c, 900 c for 3h, 6h, 9h, 12h, 15h, 20h, 24h. Because the first to-be-sintered object and the second to-be-sintered object are mixed before sintering treatment, the temperature and the time of the sintering treatment are favorable for the reaction of the first lithium-supplementing material precursors to generate corresponding first lithium-supplementing materials, and at least part of the second lithium-supplementing materials 2 are embedded into the particles 1 of the first lithium-supplementing materials; on the other hand, as shown in fig. 1 to 5, the second lithium-supplementing material 2 may be melted and inserted into the particles 1 of the first lithium-supplementing material or bonded to the surface thereof, when the surface of the particles 1 of the first lithium-supplementing material has cracks, the second lithium-supplementing material 2 may be melted and bonded to the cracks, and when the first lithium-supplementing material includes primary particles and secondary particles, the secondary particles are formed by aggregating a plurality of primary particles, and gaps are provided between the plurality of primary particles, the second lithium-supplementing material 2 may be filled in the gaps, so that the first lithium-supplementing material and the second lithium-supplementing material 2 may be tightly bonded in the above various ways, and the prepared composite lithium-supplementing material has the properties of good structural stability, high lithium-supplementing capacity, high lithium ion conductivity, and superior comprehensive properties to the existing lithium-supplementing materials.
Finally, when the encapsulation layer 3 is further required in the prepared composite lithium supplementing material, the method may further include a step of forming the encapsulation layer 3 on the surface of the sintered product:
s20: and mixing the nuclear body with a carbon source and then performing heat treatment by taking the sintered product as the nuclear body.
The core may be combined with a carbon source (e.g., phenolic resin) in a mass ratio of 100:0.5 to 100:15 (e.g., 100:1), and then heat-treating the mixture for 2 to 9 hours (e.g., 3 hours) at 400 to 700 ℃ (e.g., 450 ℃) in a protective atmosphere, carbonizing a carbon source to form a carbon coating layer as an encapsulation layer 3, and coating the core body in the carbon coating layer to obtain the composite lithium supplementing material containing the coating layer.
In order to make the encapsulation layer 3 contain the second lithium-supplementing material 2, the core body and the carbon source may be mixed and then the second lithium-supplementing material 2 may be added to be mixed and then heat-treated, and the heat treatment temperature may be appropriately increased so that the second lithium-supplementing material 2 may be melted and flowed into the encapsulation layer when the carbon source is carbonized to form the encapsulation layer, and finally the second lithium-supplementing material 2 is contained in the encapsulation layer 3, thereby increasing the lithium-supplementing capacity of the composite lithium-supplementing material.
A third aspect of the embodiments provides a positive electrode, including a current collector and a positive electrode active material layer bonded to the current collector, where the positive electrode active material layer contains the composite lithium supplementing material of the embodiments or contains the composite lithium supplementing material prepared by the preparation method of the embodiments.
The composite lithium supplementing material prepared by the preparation method of the embodiment of the application has the characteristics of stable structure, high lithium supplementing capacity and high lithium ion conductivity, so that lithium ions consumed in the first charge and discharge of the battery prepared by the positive electrode can be supplemented, the positive electrode of the embodiment of the application has high lithium supplementing capacity, and the first efficiency and the energy density of the battery containing the positive electrode of the embodiment of the application are improved.
A fourth aspect of the embodiments provides a secondary battery comprising the positive electrode of the embodiments.
The secondary battery provided by the embodiment of the application has high initial efficiency and energy density due to the inclusion of the positive electrode of the embodiment of the application.
The following description is made with reference to specific embodiments.
Example A1
The embodiment provides a composite lithium supplementing material and a preparation method thereof, wherein the composite lithium supplementing material comprises a chemical formula of Li 5 FeO 4 The chemical formula of the first lithium supplementing material is Li 3 And N is a second lithium supplementing material, wherein one part of the second lithium supplementing material is embedded into the particles of the first lithium supplementing material (the particles of the first lithium supplementing material are provided with cracks, one part of the second lithium supplementing material is combined in the cracks), and the other part of the second lithium supplementing material is combined on the surfaces of the particles of the first lithium supplementing material. And the content of the second lithium supplementing material in the surface layer is larger than that in the interior of the particles of the first lithium supplementing material. The composite lithium supplementing material further comprises a carbon packaging layer, the first lithium supplementing material and the second lithium supplementing material form a core body, and the carbon packaging layer coats the core body.
The particle diameter D50 of the first lithium supplementing material is 3.21 mu m; the second lithium supplementing material accounts for 3% of the total mass of the composite lithium supplementing material, and the particle size D50 is 132nm.
The preparation method of the composite lithium supplementing material comprises the following steps:
s1: providing a first object to be burned and a second object to be burned
Iron oxide Fe 2 O 3 The molar ratio of the lithium hydroxide to the LiOH is 0.5:5, uniformly mixing to obtain a first lithium supplementing material precursor, sintering for 13 hours at 700 ℃ in nitrogen atmosphere to obtain a first lithium supplementing material, and crushing to obtain a first to-be-sintered object;
providing nano Li 3 N is used as a second lithium supplementing material, namely a second to-be-burned object.
S2: sintering treatment
The first to-be-burned object and the second to-be-burned object are mixed according to the mass ratio of 97:3, mixing, and sintering for 6 hours at 600 ℃ in nitrogen atmosphere, wherein the second lithium supplementing material is melted and embedded into the particles of the first lithium supplementing material, and the content of the second lithium supplementing material in the surface layer of the particles of the first lithium supplementing material is larger than the content of the inside of the particles of the first lithium supplementing material, so as to obtain a compound of the second lithium supplementing material embedded into the particles of the first lithium supplementing material.
S3: forming a packaging layer
The composite and phenolic resin (carbon source) in the step S2 are mixed according to the mass ratio of 100:1, mixing, and sintering for 3 hours at 450 ℃ in nitrogen atmosphere to obtain the composite lithium supplementing material containing the carbon packaging layer.
Example A2
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: change chemical formula into Li 5 AlO 4 Is of the formula Li 3 The second lithium-supplementing material of P is otherwise identical.
The preparation process differs from example A1 only in that: in the step S1, the mol ratio of the aluminum oxide to the lithium hydroxide is 0.5:5, uniformly mixing; li in step S2 3 N is changed into Li 3 P is the same as the others.
Example A3
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: change chemical formula into Li 6 MnO 4 Is of the formula Li 2 The second lithium supplementing material of Se is the same as the other materials.
The preparation process differs from example A1 only in that: in the step S1, the mol ratio of manganese oxide to lithium hydroxide is 1:6, uniformly mixing; li in step S2 3 N is changed into Li 2 Se, all others are the same.
Example A4
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: the second lithium supplementing material accounts for 0.01% of the total mass of the composite lithium supplementing material, and all the other materials are the same.
The preparation process differs from example A1 only in that: in the step S2, the mass ratio of the first to-be-burned object to the second to-be-burned object is changed to 99.99:0.01, all others being identical.
Example A5
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: the second lithium supplementing material accounts for 22% of the total mass of the composite lithium supplementing material, and all the other materials are the same.
The preparation process differs from example A1 only in that: in step S2, the mass ratio of the first to-be-burned object to the second to-be-burned object is changed to 78:22, all others being identical.
Example A6
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: the second lithium-supplementing material is uniformly distributed in the particles of the first lithium-supplementing material, and the other materials are the same.
The preparation process differs from example A1 only in that: in the step S1, the first lithium supplementing material precursor is directly used as a first to-be-sintered object in the step S2 without sintering, and the sintering temperature and the sintering time in the step S2 are changed to 900 ℃ for 13 hours, and the other materials are the same. Thus, as the precursor of the first lithium supplementing material is sintered into the first lithium supplementing material step by step, the second lithium supplementing material is melted and uniformly distributed in the particles of the first lithium supplementing material.
Example A7
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: the encapsulation layer is not included, and all others are the same.
The preparation process differs from example A1 only in that: the composite obtained in the step S2 is used as the prepared composite lithium supplementing material without the step S3.
Example A8
The embodiment provides a composite lithium supplementing material and a preparation method thereof. The composite lithium supplementing material differs from example A1 only in that: the particles of the first lithium supplementing material comprise primary particles and secondary particles, the secondary particles are formed by gathering a plurality of primary particles, gaps are formed among the primary particles, part of the second lithium supplementing material is filled in the gaps, and the other parts are identical.
The preparation method differs from step example A1 only in that the sintering process of step S2 is adjusted to:
s2: sintering treatment
The first to-be-burned object and the second to-be-burned object are mixed according to the mass ratio of 97:3, mixing, ball milling for 1-20 h according to the ball-material ratio of 10:1 and 25Hz, and sintering for 7h at 550 ℃ in nitrogen atmosphere, wherein the second lithium supplementing material is slowly filled in gaps among a plurality of primary particles of the first lithium supplementing material.
Comparative example A1
This comparative example provides a lithium supplementing material and a method of preparing the same. The composite lithium supplementing material differs from example A1 only in that: the second lithium supplementing material is not contained, and all the other materials are the same.
The preparation process differs from example A1 only in that: the first lithium supplementing material in the step S1 is directly applied to the step S3 for encapsulation without the step S2.
Comparative example A2
This comparative example provides a lithium supplementing material and a method of preparing the same. The composite lithium supplementing material differs from example A1 only in that: the encapsulation layer encapsulates the second lithium-supplementing material without the first lithium-supplementing material.
The preparation process differs from example A1 only in that: the step of providing the first to-be-burned object in the step S1 is not included, and the second lithium supplementing material in the step S1 is directly applied to the step S3 for packaging.
Lithium ion battery examples:
the composite lithium-supplementing material provided in the above examples A1 to A8 and the lithium-supplementing materials provided in the comparative examples A1 and A2 were assembled into a positive electrode sheet and a lithium ion battery, respectively, according to the following methods:
the preparation of the positive plate is as follows: positive electrode active material (lithium iron phosphate), SP (conductive carbon black), PVDF (polyvinylidene fluoride), NMP (N-methyl pyrrolidone) and the lithium supplementing materials are mixed according to the mass ratio of 92:3.5:4.5:100:2, stirring for 2 hours by using a ball mill stirrer to obtain positive electrode slurry; adding the prepared positive electrode slurry on an aluminum foil, uniformly scraping the positive electrode slurry by a scraper, drying at 130 ℃, and rolling under 10MPa pressure to obtain a rolled pole piece, and cutting a wafer with the diameter of 15mm in the middle area;
and (3) a negative electrode: a metallic lithium sheet;
electrolyte solution: liPF (LiPF) 6 The molar concentration of (2) is 1.0mol/L, and the volume ratio of the solvent is 1:1 and dimethyl carbonate;
a diaphragm: celgard 2400 microporous membrane
The battery assembly process is as follows: and stacking the positive electrode, the diaphragm and the negative electrode in sequence respectively, so that the diaphragm is positioned between the positive electrode and the negative electrode to play a role in isolation, and obtaining the electrode assembly through a lamination process. And (3) respectively placing the electrode assemblies in an outer package, drying, injecting electrolyte, and performing vacuum packaging, standing, formation, shaping and other procedures to obtain CR2025 button cells.
The batteries made of the composite lithium-supplementing material provided in the embodiment A1 are denoted as a lithium ion battery embodiment B1 and the batteries made of the composite lithium-supplementing material provided in the embodiment A2 are denoted as a lithium ion battery embodiment B2, and the same is repeated until the lithium ion batteries are denoted as an embodiment B3 to an embodiment B8, a lithium ion battery comparative example B1 and a comparative example B2.
Correlation performance test and result analysis
1. And (3) relevant testing of the composite lithium supplementing material:
SEM characterization is performed on the composite lithium-supplementing material prepared in example A1, as shown in FIG. 6, wherein a part of the second lithium-supplementing material is embedded into the particles of the first lithium-supplementing material, and the other part is combined with the surfaces of the particles of the first lithium-supplementing material.
2. Related testing of lithium ion batteries:
the electrochemical performance of each lithium ion battery assembled in the above lithium ion battery examples was tested under the following conditions:
the battery is charged and discharged for the first time at 0.1C, and then circulated for 200 times at 0.5C and 1C respectively, and the charge and discharge cut-off voltage is 2.0-3.75V, and the electrochemical performances of the lithium ion battery examples B1 to B8 and the comparative examples B1 and B2 are obtained through a blue battery tester method.
The lithium-supplementing capacity in table 1 refers to the first charge capacity (152 mAh/g) of each battery prepared by using the lithium-supplementing material for the lithium iron phosphate material, i.e., each battery, compared with the battery prepared by using the lithium iron phosphate material without the lithium-supplementing agent according to the same process, and the difference is the lithium-supplementing capacity.
The test results are shown in table 1 below:
TABLE 1
As can be seen from table 1, the first charge specific capacity, the 0.5C and the 1C cyclic capacity retention rates of the lithium ion batteries of examples B1 to B8 are higher than those of the lithium ion batteries of comparative examples B1 and B2, and the first charge specific capacity, the 0.5C and the 1C cyclic capacity retention rates of the lithium ion batteries are higher than those of the lithium ion batteries of comparative examples B1 and B2.
As can be seen from the electrochemical data of examples B1 to B3, when the types of the first and second lithium-supplementing materials in the composite lithium-supplementing material are changed, the prepared composite lithium-supplementing material still has a higher lithium-supplementing capacity.
As can be seen from the electrochemical data of examples B4 and B5, when the compounding ratio of the first lithium-compensating material and the second lithium-compensating material in the composite lithium-compensating material exceeds a certain range, the prepared composite lithium-compensating material affects the electrochemical performance of the positive electrode material, and the lithium-compensating amount is low because the second lithium-compensating material in the composite lithium-compensating material of example A4 occupies too low ratio as shown in example A4; similarly, the second lithium-supplementing material in the composite lithium-supplementing material of embodiment A5 has too high a ratio, so that the prepared composite lithium-supplementing material has unstable structure and low lithium supplementing amount, and further the electrochemical performance of the cathode material is reduced.
As is clear from example B6, since the second lithium-compensating material in the composite lithium-compensating material of example A6 is uniformly distributed in the particles of the first lithium-compensating material, but the content of the second lithium-compensating material in the surface layer of the particles of the first lithium-compensating material is not larger than the content in the particles as in example A1, the delithiation effect is slightly lower than that of the composite lithium-compensating material of example A1, and the corresponding properties such as the lithium-compensating amount are also slightly lower.
As can be seen from example B7, since the composite lithium-compensating material in example A7 does not include the encapsulation layer, the conductivity of the composite lithium-compensating material is low, and thus the electrical properties of the battery fabricated therefrom are also low relative to those of examples A1 to A3.
As shown in example B8, when a part of the second lithium-supplementing material is filled in the gaps between the primary particles in the first lithium-supplementing material, the prepared composite lithium-supplementing material still has a higher lithium-supplementing capacity.
The foregoing description of the preferred embodiments of the present application is not intended to be limiting, but is intended to cover any and all modifications, equivalents, and alternatives falling within the spirit and principles of the present application.

Claims (12)

1. The composite lithium supplementing material is characterized in that: comprises a first lithium supplementing material and a second lithium supplementing material, wherein at least part of the second lithium supplementing material is embedded into particles of the first lithium supplementing material;
the first lithium supplementing material is a lithium-rich metal oxide, the second lithium supplementing material is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material are different.
2. The composite lithium-supplementing material of claim 1, wherein: the chemical formula of the first lithium supplementing material comprises Li a M b O c Wherein a is more than 1 and less than or equal to 8, b is more than 0 and less than 5, c is more than 0 and less than 7, and M comprises at least one of Fe, ni, mn, cu, zn, co, al, cr, zr, sb, ti, V, mo, sn; and/or
The chemical formula of the second lithium supplementing material comprises Li x A y Wherein x is more than 0 and less than or equal to 5, y is more than 0 and less than 4, and A comprises at least one of P, S, F, B, O, se, N.
3. The composite lithium-supplementing material of claim 1, wherein: the first lithium supplementing material comprises secondary particles, the secondary particles are formed by gathering a plurality of primary particles, gaps are arranged among the primary particles, and at least part of the second lithium supplementing material is filled in the gaps; and/or
The particles of the first lithium-supplementing material have cracks, and at least a portion of the second lithium-supplementing material is incorporated in the cracks.
4. A composite lithium-supplementing material according to any one of claims 1 to 3, wherein: in the particles of the first lithium supplementing material, the content of the second lithium supplementing material in the surface layer is larger than the content of the inside; and/or
The content of the second lithium supplementing material presents an increasing trend along the direction from the inside to the surface of the particles of the first lithium supplementing material.
5. A composite lithium-supplementing material according to any one of claims 1 to 3, wherein: the second lithium supplementing material is also combined on the surface of the first lithium supplementing material.
6. A composite lithium-supplementing material according to any one of claims 1 to 3, wherein: the particle size of the first lithium supplementing material is larger than that of the second lithium supplementing material; and/or
The particle size D50 of the first lithium supplementing material is 0.5-70 mu m; and/or
The second lithium supplementing material accounts for 0.1-20% of the total mass of the composite lithium supplementing material; and/or
The particle size D50 of the second lithium supplementing material is 5-1000 nm; and/or
The particle diameter D50 of the composite lithium supplementing material is 0.5-100 mu m; and/or
The specific surface area of the composite lithium supplementing material is 0.5-60 m 2 /g; and/or
The residual alkali content of the composite lithium supplementing material is less than or equal to 15 percent.
7. A composite lithium-supplementing material according to any one of claims 1 to 3, wherein: the first lithium supplementing material and the second lithium supplementing material form a core body, and the core body further comprises an encapsulation layer, wherein the encapsulation layer encapsulates the core body.
8. The composite lithium-supplementing material of claim 7, wherein:
the thickness of the packaging layer is 1-1000 nm; and/or
The material of the packaging layer comprises at least one of carbon material, oxide, carbide, nitride, sulfide, phosphate and lithium ion conductor material; and/or
The second lithium supplementing material is also contained in the packaging layer; and/or
The packaging layer accounts for 0.1% -15% of the mass of the composite lithium supplementing material.
9. The preparation method of the composite lithium supplementing material is characterized by comprising the following steps of:
mixing the first to-be-burned object and the second to-be-burned object, and then sintering in a protective atmosphere to obtain a composite lithium supplementing material;
the first to-be-burned object comprises at least one of a first lithium supplementing material and a first lithium supplementing material precursor, and the first lithium supplementing material is a lithium-rich metal oxide;
the second to-be-burned object comprises a second lithium supplementing material, the second lithium supplementing material is a binary lithium-rich material, and the first lithium supplementing material and the second lithium supplementing material are different.
10. The method of manufacturing according to claim 9, wherein: the temperature of the sintering treatment is 500-900 ℃; and/or
The sintering treatment time is 3-24 hours; and/or
The mass ratio of the first to-be-burned object to the second to-be-burned object is 80:20 to 99.9:0.1; and/or
The method further comprises the step of forming an encapsulation layer on the surface of the sintered product:
and taking the sintered product as a nucleus, mixing the nucleus with a carbon source, and then carrying out heat treatment.
11. A positive electrode, characterized in that: including the current collector and combine the anodal active material layer on this current collector, its characterized in that: the positive electrode active material layer contains the composite lithium-supplementing material according to any one of claims 1 to 8 or the composite lithium-supplementing material produced by the production method according to claim 9 or 10.
12. A secondary battery characterized in that: comprising the positive electrode of claim 11.
CN202311281371.7A 2023-09-28 2023-09-28 Composite lithium supplementing material and preparation method and application thereof Pending CN117276508A (en)

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