CN115347188A - Positive electrode additive and preparation method and application thereof - Google Patents

Positive electrode additive and preparation method and application thereof Download PDF

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Publication number
CN115347188A
CN115347188A CN202210801275.XA CN202210801275A CN115347188A CN 115347188 A CN115347188 A CN 115347188A CN 202210801275 A CN202210801275 A CN 202210801275A CN 115347188 A CN115347188 A CN 115347188A
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positive electrode
core material
binder
initiator
microcapsule
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谭旗清
万远鑫
孔令涌
张莉
裴现一男
赖佳宇
赵中可
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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 CN202210801275.XA priority Critical patent/CN115347188A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
    • B01J13/02—Making microcapsules or microballoons
    • B01J13/04—Making microcapsules or microballoons by physical processes, e.g. drying, spraying
    • B01J13/043—Drying and spraying
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • 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
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The application relates to the technical field of lithium ion battery anode materials, in particular to an anode additive and a preparation method and application thereof. The positive electrode additive comprises a microcapsule repairing agent and an initiator, wherein the microcapsule repairing agent comprises a core material and a wall material wrapped outside the core material, and the initiator is used for reacting with the core material or initiating a polymerization reaction of the core material; the microcapsule repairing agent is prepared by wrapping a core material by using a natural or synthetic high-molecular film forming material and arranging an initiator outside the microcapsule repairing agent; the initiator is used for reacting with the core material or initiating the polymerization reaction of the core material, can achieve the effect of adhesion repair, and can be applied to self-repair treatment of the pole piece damaged to generate microcracks in the adhesive.

Description

Positive electrode additive and preparation method and application thereof
Technical Field
The application belongs to the technical field of lithium ion battery anode materials, and particularly relates to an anode additive and a preparation method and application thereof.
Background
A lithium ion battery is a secondary battery (rechargeable battery) that mainly operates by movement of lithium ions between a positive electrode and a negative electrode. During charging and discharging, li + Intercalation and deintercalation to and from two electrodes: upon charging, li + The lithium ion battery is extracted from the positive electrode and is inserted into the negative electrode through the electrolyte, and the negative electrode is in a lithium-rich state; the opposite is true during discharge.
The electrode of the lithium battery is prepared by uniformly stirring an active substance, a conductive agent and a binder in a solvent, coating the mixture on a current collector and drying the mixture. The binder well adheres the active substance and the conductive agent together, ensures that the battery has good conductivity in the charging and discharging process, and ensures that lithium ions cannot fall off from the current collector in the embedding and releasing process between the anode and the cathode. Thus, the binder plays an important role in the stability of the lithium battery.
The most widely used lithium battery positive binder at present is polyvinylidene fluoride (PVDF), and in the use process of a lithium battery, the volume is obviously changed due to lithium intercalation/lithium deintercalation, the tensile strength of the binder is high, but the elongation at break is small, so that the active material and the binder are further crushed and fall off. Finally leading to pulverization of the electrode slice, capacity reduction and shortened service life. Therefore, it is highly desirable to provide a binder for a lithium battery positive electrode, which can suppress pulverization of a lithium-rich positive electrode sheet and prolong the service life of a lithium ion battery.
Disclosure of Invention
The application aims to provide a positive electrode additive and a preparation method and application thereof, and aims to solve the problem that in the prior art, a binder of a positive electrode of a lithium battery is easy to break and fall off, so that electrode plates are pulverized.
In order to achieve the purpose of the application, the technical scheme adopted by the application is as follows:
in a first aspect, the present application provides a positive electrode additive, which includes a microcapsule repairing agent and an initiator, wherein the microcapsule repairing agent includes a core material and a wall material wrapped outside the core material, and the initiator is configured to react with the core material or to initiate a polymerization reaction of the core material.
In a second aspect, the present application provides a method for preparing a positive electrode additive, comprising the steps of:
providing a core material and a wall material, mixing the core material and the wall material, and then carrying out spray drying treatment to obtain a microcapsule repairing agent;
and mixing the microcapsule repairing agent and the initiator to obtain the positive electrode additive.
In a third aspect, the present application provides a positive electrode binder, where the positive electrode binder includes a binder and a positive electrode additive dispersed in the binder, and the positive electrode additive is a positive electrode additive or is prepared by a preparation method of the positive electrode additive.
In a fourth aspect, the present application provides a lithium-rich positive electrode comprising a lithium-rich positive electrode material, a conductive agent, and a binder, wherein the binder is a positive electrode binder.
In a fifth aspect, the present application provides a secondary battery including a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode, wherein the positive electrode is a lithium-rich positive electrode.
The additive comprises a microcapsule repairing agent and an initiator, wherein the microcapsule repairing agent comprises a core material and a wall material wrapped outside the core material, and the initiator is used for reacting with the core material or initiating the core material to perform a polymerization reaction; the microcapsule repairing agent is prepared by wrapping a core material by using a natural or synthetic high-molecular film forming material and arranging an initiator outside the microcapsule repairing agent; the initiator is used for reacting with the core material or initiating the polymerization reaction of the core material, can achieve the effect of adhesion repair, and can be applied to self-repairing treatment of the pole piece damaged to generate microcracks in the adhesive.
According to the preparation method of the positive electrode additive provided by the second aspect of the application, the core material and the wall material are only needed to be provided to prepare the microcapsule, and then the microcapsule and the initiator are mixed to obtain the positive electrode additive.
The positive electrode binder provided by the third aspect of the present application comprises a binder matrix and a positive electrode additive dispersed in the binder matrix; the positive electrode additive comprises a microcapsule repairing agent and an initiator; the technology of adding microcapsule repairing agent into binder matrix material is adopted for modification treatment, wherein the microcapsule repairing agent technology is to wrap a core material by utilizing natural or synthetic polymer film forming material, and an initiator is arranged outside the microcapsule repairing agent; when the pole piece is damaged to generate micro cracks, the initiator is used for reacting with the core material or initiating the core material to generate polymerization reaction so as to achieve the effect of adhesion repair, and the lithium ion battery has the advantages of high self-repair efficiency and strong mechanical strength, and the core material and the initiator can repair the damage spontaneously at room temperature, the mechanical property is recovered, and the pulverization of the positive pole piece can be inhibited; in addition, the binder containing the microcapsule repairing agent has good stretchability and repairability, ensures that the active substances and the conductive agent are adhered to the current collector in the using process and do not crack or fall powder, and effectively improves the service life and the cycling stability of the battery.
The lithium-rich positive electrode provided by the fourth aspect of the application comprises a lithium-rich positive electrode material, a conductive agent and a binder, wherein the provided binder is a positive electrode binder which comprises a binder matrix, a microcapsule repairing agent and an initiator, wherein the microcapsule repairing agent and the initiator are dispersed in the binder matrix, and when a pole piece is damaged to generate microcracks, the initiator is used for reacting with a core material or is used for initiating a polymerization reaction of the core material and achieving the effect of adhesion repairing.
The fifth aspect of the application provides a secondary battery, secondary battery includes the positive pole, the negative pole and the diaphragm of locating between positive pole and negative pole with folding, the positive pole is the rich lithium positive pole that contains the anodal binder that provides, in the use, when the pole piece is destroyed and is produced the crazing line, the initiator that the anodal binder in the rich lithium positive pole contains is used for reacting with the core material, or be used for initiating the core material to take place polymerization and reach the prosthetic effect of bonding, certain selfreparing effect has, and can guarantee the stretchability and the repairability of material, ensure that active material, the mass flow body of conductive agent etc. adhere on, do not ftracture, do not fall the powder, improve battery wholeness ability.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a graph showing the results of tensile strength tests provided in the examples of the present application.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application more clearly apparent, 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 merely illustrative of the present application and are not intended to limit the present application.
In this application, the term "and/or" describes an association relationship of associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a alone, A and B together, and B alone. Wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
In the present application, "at least one" means one or more, "a plurality" means two or more. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, "at least one (one) of a, b, or c," or "at least one (one) 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, and c can be single or multiple respectively.
It should be understood that, in various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, some or all of the steps may be executed in parallel or executed sequentially, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.
The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the examples of this application 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 weight of the related components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of the weight among the components, and therefore, the content of the related components is scaled up or down within the scope disclosed in the description of the embodiments of the present application as long as it is scaled up or down according to the description of the embodiments of the present application. Specifically, the mass in the description of the embodiments of the present application may be in units of mass known in the chemical industry, such as μ g, mg, g, and kg.
The terms "first" and "second" are used for descriptive purposes only and are used for distinguishing purposes such as substances from one another and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. 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 defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
The embodiment of the application provides a positive electrode additive in a first aspect, the positive electrode additive comprises a microcapsule repairing agent and an initiator, the microcapsule repairing agent comprises a core material and a wall material wrapped outside the core material, and the initiator is used for reacting with the core material or initiating a polymerization reaction of the core material.
According to the positive electrode additive provided by the first aspect of the embodiment of the application, the additive comprises a microcapsule repairing agent and an initiator, the microcapsule repairing agent comprises a core material and a wall material wrapped outside the core material, and the initiator is used for reacting with the core material or initiating a polymerization reaction of the core material; the microcapsule repairing agent is prepared by wrapping a core material by using a natural or synthetic high-molecular film forming material and arranging an initiator outside the microcapsule repairing agent; the initiator is used for reacting with the core material or initiating the polymerization reaction of the core material, can achieve the effect of adhesion repair, and can be applied to self-repairing treatment of the pole piece damaged to generate microcracks in the adhesive.
In some embodiments, the initiator need only be in the vicinity of the microcapsule repair agent to effect reaction with the core material or to initiate polymerization of the core material.
In some embodiments, the initiator may be disposed around the microcapsule repair agent or form an initiator coating layer that coats the outer surface of the microcapsule repair agent.
In some embodiments, the initiator comprises a catalyst or a reactant, and the catalyst is selected as the initiator and can catalyze the core material to perform polymerization reaction; and selecting a reactant as an initiator, wherein the initiator and the core material are subjected to chemical reaction together in the reaction process to realize the repairing effect.
When the lithium-rich pole piece is damaged, the capsule wall of the microcapsule repairing agent of the positive additive is broken, the core material flows out, and the core material is contacted with the initiator to react; wherein, the catalyst is selected as an initiator, and can catalyze the core material to generate polymerization reaction; and selecting a reactant as an initiator, wherein the initiator and the core material are subjected to chemical reaction together in the reaction process to realize the repairing effect.
In some embodiments, the initiator is selected from a grubbs catalyst and the core material is selected from at least one of an olefinic organic and an acyclic diene organic.
In some embodiments, the glassine catalyst comprises at least one of benzylidene-bis (tricyclohexylphosphine) ruthenium dichloride, benzylidene- [1, 3-bis (trimethylphenyl) -2-imidazolinylidene ] · dichloro (tricyclohexylphosphine) ruthenium, and [1, 3-bis (2, 4, 6-trimethylphenyl) -2-imidazolidinylidene ] bis (2-bromopyridine) (phenylmethylene) ruthenium dichloride.
In some embodiments, the olefinic organic includes at least one of dicyclopentadiene monomer, 5-ethylene-2-bornylene.
In some embodiments, the acyclic diene-based organic substance includes at least one of diethyl diallylmalonate, dimethyl allylmalonate, diethyl allylmalonate.
In some embodiments, the initiator is selected from organotin-based catalysts and the core material is selected from organosilane-based organics.
In some embodiments, the organotin-based catalyst includes at least one of dimethyltin dineodecanoate, dibutyltin oxide, dibutyltin dilaurate.
In some embodiments, the organosilane-based organic material comprises at least one of polydimethylsiloxane, trimethylmethoxysilane, trimethylchlorosilane.
In some embodiments, the initiator is selected from furan group-based reactants and the core material is selected from maleimide-based organics. When the core material is selected from maleimide organic matters, when the pole piece is damaged, the maleimide organic matters flow out and generate Diels-Alder reaction (Diels-Alder, DA) with furan group reactants to achieve the effect of curing and bonding.
In some embodiments, the furan-based reactant includes at least one of 5-hydroxymethylfurfural, dibenzofuran, 2, 5-furandicarbaldehyde.
In some embodiments, the maleimide-based organic comprises at least one of maleimide, an N-substituted maleimide monomer, N-phenylmaleimide, N-benzylmaleimide, N-cyclohexylmaleimide, N-p-hydroxymaleimide, and N-p-carboxymaleimide.
Further, the microcapsule repairing agent comprises a core material and a wall material wrapping the core material. In some embodiments, the wall material comprises at least one of gelatin, gum arabic, carboxymethylcellulose, ethylcellulose, dextrins, chitosan.
In some embodiments, the mass ratio of wall material to core material is 1:0.5 to 1.5; when the quality of the wall material is controlled to be constant, the larger the quality of the core material is, the higher the coating rate is, and more core materials can be coated.
In some embodiments, the mass ratio of the wall material to the core material is 1:0.5, 1:0.7, 1:0.9, 1:1. 1:1.2, 1:1.4, 1:1.5.
in some embodiments, the microcapsule repair agent has a particle size of 10 to 120 microns. If the particle size of the microcapsule repairing agent is too small, the microcapsules can be agglomerated in the binder, so that the microcapsule repairing agent is not beneficial to dispersion and subsequent repairing of the pole piece; if the particle size of the microcapsule repairing agent is too large, the particle size of the microcapsule repairing agent exceeds that of a common binder, so that the preparation of a pole piece is not facilitated.
In some embodiments, the microcapsule repair agent has a particle size of 10 microns, 20 microns, 30 microns, 40 microns, 50 microns, 60 microns, 70 microns, 80 microns, 90 microns, 100 microns, 110 microns, 120 microns.
In some embodiments, the wall material has a thickness of 0.2 to 10 micrometers. In some embodiments, the wall material has a thickness of 0.2 microns, 0.5 microns, 0.7 microns, 0.9 microns, 1 micron, 1.5 microns, 2 microns, 2.5 microns, 3 microns, 3.5 microns, 4 microns, 4.5 microns, 5 microns, 5.5 microns, 6 microns, 6.5 microns, 7 microns, 7.5 microns, 8 microns, 8.5 microns, 9 microns, 9.5 microns, 10 microns.
In a second aspect of the embodiments of the present application, there is provided a method for preparing a positive electrode additive, including the steps of:
G01. providing a core material and a wall material, mixing the core material and the wall material, and then carrying out spray drying treatment to obtain a microcapsule repairing agent;
G02. and mixing the microcapsule repairing agent and the initiator to obtain the positive electrode additive.
According to the preparation method of the cathode additive provided by the second aspect of the embodiment of the application, the core material and the wall material are only needed to be provided to prepare the microcapsule, and then the microcapsule and the initiator are mixed to obtain the cathode additive.
And G01, mixing the core material and the wall material, and then carrying out spray drying treatment to obtain the microcapsule repairing agent. The selection of the type and quality of the core and wall materials, such as those discussed above, will not be discussed herein for brevity.
In some embodiments, the wall material is dissolved in an aqueous solution at an optimum temperature to obtain a wall material aqueous solution material, the core material and the wall material aqueous solution material are mixed, stirred and uniformly mixed, the obtained mixed solution is homogenized by a colloid mill, and spray drying is performed under certain conditions to obtain the microcapsule repairing agent.
In some embodiments, the step of performing a spray drying process comprises: spray drying treatment is carried out under the conditions that the air inlet temperature is 80-100 ℃, the air outlet temperature is 60-80 ℃ and the homogenizing pressure is 35-50 MPa.
And G02, mixing the microcapsule repairing agent and the initiator to obtain the positive electrode additive.
The type and amount of initiator provided is selected as discussed above and will not be discussed further herein for brevity.
The positive electrode additive can be obtained only by mixing the microcapsule repairing agent and the initiator.
In a third aspect of the embodiments of the present application, a positive electrode binder is provided, where the positive electrode binder includes a binder matrix and a positive electrode additive dispersed in the binder matrix, and the positive electrode additive is a positive electrode additive or is prepared by a preparation method of the positive electrode additive.
In the positive electrode binder provided by the third aspect of the embodiments of the present application, the positive electrode binder includes a binder matrix and a positive electrode additive dispersed in the binder matrix; the positive electrode additive comprises a microcapsule repairing agent and an initiator; the microcapsule repairing agent is modified by adding the microcapsule repairing agent into a binder matrix material, wherein the microcapsule repairing agent is prepared by wrapping a core material by using a natural or synthetic high-molecular film-forming material and arranging an initiator outside the microcapsule repairing agent; when the pole piece is damaged to generate micro cracks, the initiator is used for reacting with the core material or initiating the core material to generate polymerization reaction so as to achieve the effect of adhesion repair, and the lithium ion battery has the advantages of high self-repair efficiency and strong mechanical strength, and the core material and the initiator can repair the damage spontaneously at room temperature, the mechanical property is recovered, and the pulverization of the positive pole piece can be inhibited; in addition, the binder containing the microcapsule repairing agent has good stretchability and repairability, ensures that the active substances and the conductive agent are adhered to the current collector in the using process and do not crack or fall powder, and effectively improves the service life and the cycling stability of the battery.
In some embodiments, the mass ratio of the binder matrix to the microcapsule repair agent to the initiator is 90-99: 0.5 to 5:0.5 to 5.
The content of the microcapsule repairing agent is controlled within a proper range, and when the content of the microcapsule repairing agent is too low, the microcapsule repairing agent is difficult to repair the damage of the pole piece well; however, when the content of the microcapsule repairing agent is too high, more channels such as microcracks and the like can be generated in the pole piece, which is beneficial to the diffusion of corrosive media, so that the shielding performance of the pole piece is reduced.
Correspondingly, the preparation method of the cathode binder comprises the following steps:
and uniformly mixing the positive electrode additive, the binder matrix and a proper amount of organic solvent, and drying to obtain the positive electrode binder.
The preparation method of the positive electrode additive is as discussed above, and is not repeated here for saving space.
Further, the binder matrix is selected from the binder types conventionally used for the positive electrode plate of the lithium ion battery, including but not limited to polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), sodium Alginate (SA), polymethyl methacrylate (PMMA), hydrogenated Nitrile Butadiene Rubber (HNBR), and the like.
The method for uniformly mixing the positive electrode additive, the binder matrix and a proper amount of organic solvent comprises the following steps: uniformly mixing the microcapsule repairing agent, the initiator, the binder matrix and a proper amount of organic solvent.
In some embodiments, the step of weighing the microcapsule repairing agent, the initiator and the binder matrix comprises: the microcapsule repairing agent and the initiator are mixed firstly and then are mixed evenly with the binder matrix.
In other embodiments, the step of weighing the microcapsule repairing agent, the initiator and the binder matrix comprises: uniformly mixing the microcapsule repairing agent, the initiator and the binder matrix.
In still other embodiments, the step of weighing the microcapsule repair agent, the initiator, and the binder matrix comprises: the microcapsule repairing agent and the binder matrix are uniformly mixed first and then are uniformly mixed with the microcapsule repairing agent.
In some embodiments, a drying process is performed to obtain a positive electrode binder; wherein the temperature for drying treatment is 40-60 ℃.
In a fourth aspect of the embodiments of the present application, a lithium-rich positive electrode is provided, where the lithium-rich positive electrode includes a lithium-rich positive electrode material, a conductive agent, and a binder, and the binder is a positive electrode binder.
The lithium-rich positive electrode provided in the fourth aspect of the embodiment of the application includes a lithium-rich positive electrode material, a conductive agent and a binder, and the provided binder is a positive electrode binder including the binder, a microcapsule repairing agent dispersed in the binder and an initiator, when a pole piece is damaged to generate microcracks, the initiator is used for reacting with a core material, or is used for initiating a core material to generate a polymerization reaction and achieve an effect of adhesion repairing, and the lithium-rich positive electrode has the advantages of high self-repairing efficiency and high mechanical strength, and mechanical properties are recovered, so that pulverization of the positive electrode piece can be inhibited, and overall performance of a battery is improved.
In some embodiments, the lithium-rich cathode material comprises a cathode active material and a lithium supplement material, wherein the lithium supplement material is 1-10wt%
In some embodiments, the lithium-rich cathode material comprises a lithium-supplementing material in a mass percent selected from 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%.
The mass ratio of the lithium-rich cathode material to the conductive agent to the cathode binder is 80-95: 0.2 to 20:0.5 to 20. If the content of the binder is too low, the active material cannot be completely bound, and volume change caused by pole piece change has a destructive effect on the generation and stability of an SEI film in the charging and discharging processes, so that the consumed irreversible capacity is increased. When the content of the binder is too large, the binding strength of the active material is increased to stabilize the structure of the electrode sheet, but the content of the active material is decreased to lower the electrochemical performance of the battery.
The lithium supplement material is used for supplementing lithium loss in the circulating process. The lithium supplement material comprises one or more of binary lithium-containing compounds and multi-element lithium-containing compounds. Alternatively, the binary lithium-containing compound comprises the formula LiaXb; wherein a is more than or equal to 1 and less than or equal to 3, B is more than or equal to 1 and less than or equal to 3, X is selected from any one of F, S, N, B, P, O and Se; the multi-element lithium-containing compound comprises a compound with a chemical formula of Li x M y O z Wherein x/y is more than 0.1 and less than 10, y is more than 0 and less than 5, and z is more than or equal to 2 and less than 10; m comprises one or more of Mn, fe, cr, co, ni, cu, zn, mg, ti, si, sn, ce, re, ru, mo or Zr.
In some embodiments, preparation of the positive electrode sheet: mixing the lithium-rich positive electrode, the conductive agent and the positive electrode binder according to the mass ratio to obtain positive electrode slurry; and coating the positive electrode slurry on a positive electrode current collector-aluminum foil, and preparing the positive electrode plate through the steps of drying, rolling, die cutting and the like.
A fifth aspect of the embodiments provides a secondary battery including a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode, wherein the positive electrode is a lithium-rich positive electrode.
The fifth aspect of the embodiment of the present application provides a secondary battery, the secondary battery includes an anode, a cathode, and a diaphragm stacked between the anode and the cathode, the anode is a provided lithium-rich anode containing an anode binder, when a pole piece is damaged to generate microcracks in a use process, an initiator contained in the anode binder in the lithium-rich anode is used to react with a core material, or is used to initiate a polymerization reaction of the core material and achieve an adhesion repairing effect, and the secondary battery has a certain self-repairing effect, can ensure the stretchability and the repairability of a material, ensures that an active material, a conductive agent, and the like are adhered to a current collector, and does not crack or fall powder, and improves the overall performance of the battery.
The following description is given with reference to specific examples.
Example A1
Microcapsule repairing agent, positive electrode binder and preparation method thereof
S1, preparing a dicyclopentadiene microcapsule repairing agent:
according to the wall material: core material =1.0:0.5, weighing a certain amount of chitosan (wall material) to be dissolved in the aqueous solution at 60 ℃, adding the dicyclopentadiene monomer into the wall material solution, stirring and uniformly mixing, homogenizing the obtained mixed solution by a colloid mill, and then carrying out spray drying at the conditions of air inlet temperature of 80 ℃, air outlet temperature of 60 ℃ and homogenizing pressure of 35MPa to prepare the dicyclopentadiene microcapsule repairing agent.
S2, preparing a positive electrode binder:
and (3) preparing dicyclopentadiene microcapsules prepared by S1: grubbs catalyst: PVDF (polyvinylidene fluoride) is 5:2.5:92.5, adding a proper amount of ethanol, uniformly mixing, and drying at 40 ℃ to obtain the PVDF positive binder containing 5% of dicyclopentadiene microcapsule repairing agent.
Example A2
Microcapsule repairing agent, positive electrode binder and preparation method thereof
S1, preparing a dicyclopentadiene microcapsule repairing agent:
according to the wall material: core =1.0:0.51, weighing a certain amount of chitosan (wall material) to be dissolved in the aqueous solution at 60 ℃, adding the dicyclopentadiene monomer into the wall material solution, stirring and uniformly mixing, homogenizing the obtained mixed solution by a colloid mill, and performing spray drying at the conditions of air inlet temperature of 80 ℃, air outlet temperature of 60 ℃ and homogenizing pressure of 35MPa to prepare the dicyclopentadiene microcapsule repairing agent.
S2, preparing the positive electrode binder:
and (2) preparing a dicyclopentadiene microcapsule repairing agent by using the S1: grubbs catalyst: PVDF (polyvinylidene fluoride) is prepared from the following components in percentage by mass 4:2.5:93.5, adding a proper amount of ethanol, uniformly mixing, and drying at 45 ℃ to obtain the PVDF positive binder containing 4% of dicyclopentadiene microcapsule repairing agent.
Example A3
Microcapsule repairing agent, positive electrode binder and preparation method thereof
S1, preparing a dicyclopentadiene microcapsule repairing agent:
according to the wall material: core =1.0:0.52, weighing a certain amount of ethyl cellulose (wall material) to dissolve in the aqueous solution at 60 ℃, adding the dicyclopentadiene monomer into the wall material solution, stirring and uniformly mixing, homogenizing the obtained mixed solution by a colloid mill, and performing spray drying at the conditions of air inlet temperature of 80 ℃, air outlet temperature of 60 ℃ and homogenizing pressure of 35MPa to prepare the dicyclopentadiene microcapsule repairing agent.
S2, preparing a positive electrode binder:
preparing a dicyclopentadiene microcapsule repairing agent prepared by S1: grubbs catalyst: PVDF (polyvinylidene fluoride) is prepared from the following components in percentage by mass: 2.5:96.5, adding a proper amount of ethanol, uniformly mixing, and drying at 45 ℃ to obtain the PVDF positive binder containing 2% of dicyclopentadiene microcapsule repairing agent.
Example A4
Microcapsule repairing agent, positive electrode binder and preparation method thereof
S1, preparation of a dimethyl siloxane microcapsule repairing agent:
according to the wall material: core material =1.0:0.51 dissolving a certain amount of chitosan (wall material) in an aqueous solution at 60 ℃, adding a dimethyl siloxane monomer into the wall material solution, stirring and uniformly mixing, homogenizing the obtained mixed solution by a colloid mill, and then carrying out spray drying at the conditions of the air inlet temperature of 85 ℃, the air outlet temperature of 60 ℃ and the homogenization pressure of 36MPa to prepare the dimethyl siloxane microcapsule repairing agent.
S2, preparing a positive electrode binder:
and (3) preparing a dimethyl siloxane microcapsule repairing agent prepared by S1: dimethyltin dineodecanoate catalyst: PVDF (polyvinylidene fluoride) is 5:2.5:92.5, adding a proper amount of ethanol, uniformly mixing, and drying at 40 ℃ to obtain the PVDF positive binder containing the dimethyl siloxane microcapsule repairing agent.
Example A5
Microcapsule repairing agent, positive electrode binder and preparation method thereof
S1, preparing a maleimide microcapsule repairing agent:
according to the wall material: core material =1.0:0.52 weighing a certain amount of carboxymethyl cellulose (wall material) to be dissolved in water solution at 60 ℃, adding maleimide monomer into the wall material solution, stirring and uniformly mixing, homogenizing the obtained mixed solution by a colloid mill, and then carrying out spray drying at the conditions of air inlet temperature of 80 ℃, air outlet temperature of 60 ℃ and homogenizing pressure of 35-50MPa to prepare the maleimide microcapsule repairing agent.
S2, preparing the positive electrode binder:
and (3) preparing a maleimide microcapsule repairing agent from S1: 5-hydroxymethylfurfural catalyst: PVDF (polyvinylidene fluoride) is 5:2.5:92.5, adding a proper amount of ethanol, uniformly mixing, and drying at 40 ℃ to obtain the PVDF positive binder containing the maleimide microcapsule repairing agent.
Comparative example A1
This comparative example provides a PVDF binder that differs from the other examples described above in that it does not contain a self-healing microcapsule material.
Examples B1 to B5
Lithium-rich positive electrode
A lithium-rich positive electrode: with the self-healing microcapsule binders provided in examples A1 to A5 as binders, respectively, the lithium supplement additive: positive electrode material =95:5, mixing to prepare a lithium-rich cathode material, and mixing according to the proportion of NMP: lithium-rich cathode material: super P: the self-repairing microcapsule binder provided in the embodiments A1 to A5 is prepared by mixing the following five materials in a mass ratio of 100; the rotation speed is set to be 30Hz; the lithium-rich positive plate is prepared by homogenizing, coating, drying and cutting, and is baked in a vacuum oven at 100 ℃ to remove trace water.
Comparative example B1
Lithium-rich positive electrode
The preparation method is identical to that of the lithium-rich positive electrodes of examples B1 to B5, except that the added binder is the PVDF binder provided in comparative example A1.
Examples C1 to C5
Lithium ion battery
A lithium-rich positive electrode: examples B1 to B5 lithium-rich positive electrodes prepared
Negative electrode: a lithium metal sheet;
electrolyte: mixing ethylene carbonate and ethyl methyl carbonate according to a volume ratio of 3 to 7, and adding LiPF6 to form an electrolyte, wherein the concentration of the LiPF6 is 1mol/L;
a diaphragm: polypropylene microporous partition;
assembling the lithium ion battery: the structure of the lithium metal sheet, the diaphragm, the electrolyte and the positive plate is assembled into the lithium ion battery in an inert atmosphere glove box.
Comparative example C1
Lithium ion battery
The preparation method was identical to that of the lithium ion batteries of examples C1 to C5, except that the lithium-rich positive electrode was the lithium-rich positive electrode provided in comparative example B1.
Performance testing
The tensile strength test comprises the following steps:
the tensile strength of the self-repairing microcapsule binder is tested by using a universal tester, a test sample bar is dumbbell-shaped, the size is 15mm multiplied by 2mm multiplied by 1mm, the tensile rate is 4mm/min, and the test temperature is 25 ℃.
(II) lithium ion battery embodiment:
the electrochemical performance of each lithium ion battery assembled in the embodiment of the lithium ion battery is tested, and the test conditions are as follows:
the first loop is charged to 4.3V with constant current and constant voltage at 0.066C multiplying power, and the cut-off current is 0.02C; standing for 10min, discharging at constant current of 0.066C multiplying power to 2.5V, charging at constant current and constant voltage of 1C multiplying power to 3.65V, and stopping current to 0.02C; and laying aside for 10min, discharging at 1C rate and constant current to 2.5V, circulating for 700 circles, and testing.
Analysis of results
(I) analysis of tensile Strength test results
FIG. 1 is a tensile curve of the binders of example A1 and comparative example A1. As can be seen from fig. 1, the self-healing microcapsule binder provided in example A1 has a higher elongation at break, indicating that it has good toughness, and the tensile curve of the remaining examples is similar to that of example A1.
(II) analysis of results of lithium ion Battery examples
The electrochemical properties of the lithium ion batteries of examples C1 to C5 and comparative example C1 are shown in table 1,
TABLE 1
Figure BDA0003737842710000151
As can be seen from table 1, the self-repairing binder provided by the invention has a high first discharge specific capacity, and after 1C cycle for 700 cycles, the specific capacity attenuation is low, and the self-repairing binder has a high capacity retention rate, which indicates that the self-repairing binder provided by the invention can automatically repair cracks of a pole piece in the charging and discharging processes of a lithium ion battery, so that the service life and the cycle stability of the lithium ion battery are effectively improved; and the lithium ion battery prepared by the commercially available PVDF binder (comparative example A1) has lower specific discharge capacity for the first time and lower capacity retention rate after 700 cycles of 1C cycle. In conclusion, the self-repairing binder prepared by adding the self-repairing binder disclosed by the invention has the characteristics of high self-repairing efficiency and stronger mechanical strength in the process of preparing the positive plate.
In summary, the positive electrode binder provided by the present application includes a binder and a positive electrode additive dispersed in the binder; the positive electrode additive comprises a microcapsule repairing agent and an initiator; the microcapsule repairing agent is modified by adding the microcapsule repairing agent into a binder material, wherein the microcapsule repairing agent is prepared by wrapping a core material by using a natural or synthetic high-molecular film-forming material and arranging an initiator outside the microcapsule repairing agent; when the pole piece is damaged to generate microcracks, the initiator is used for reacting with the core material or initiating the core material to generate a polymerization reaction so as to achieve the effect of adhesive repair, and the self-repairing composite material has the advantages of high self-repairing efficiency and high mechanical strength, and the core material and the initiator can repair the damage spontaneously at room temperature, so that the mechanical property is recovered, and the pulverization of the positive pole piece can be inhibited; in addition, the binder containing the microcapsule repairing agent has good stretchability and repairability, ensures that the active substances and the conductive agent are adhered to the current collector in the using process and do not crack or fall powder, and effectively improves the service life and the cycling stability of the battery.
The above description is only a preferred embodiment of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (10)

1. The additive is characterized by comprising a microcapsule repairing agent and an initiator, wherein the microcapsule repairing agent comprises a core material and a wall material wrapped outside the core material, and the initiator is used for reacting with the core material or initiating a polymerization reaction of the core material.
2. The positive electrode additive according to claim 1, wherein the initiator is selected from a group consisting of a glassine catalyst, and the core material is selected from at least one of an olefinic organic substance and an acyclic diene organic substance; or the like, or a combination thereof,
the initiator is selected from an organic tin catalyst, and the core material is selected from organic silane; or the like, or, alternatively,
the initiator is selected from furan group reactants, and the core material is selected from maleimide organic matters.
3. The positive electrode additive according to any one of claims 1 to 2, wherein the wall material comprises at least one of gelatin, gum arabic, carboxymethyl cellulose, ethyl cellulose, dextrin, and chitosan.
4. The positive electrode additive according to any one of claims 1 to 2,
the mass ratio of the wall material to the core material is 1:0.5 to 1.5; and/or the presence of a gas in the gas,
the particle size of the microcapsule repairing agent is 10-120 microns; and/or the presence of a gas in the gas,
the thickness of the wall material is 0.2-10 microns.
5. The preparation method of the positive electrode additive is characterized by comprising the following steps of:
providing a core material and a wall material, mixing the core material and the wall material, and then carrying out spray drying treatment to obtain a microcapsule repairing agent;
and mixing the microcapsule repairing agent with an initiator to obtain the positive electrode additive.
6. A positive electrode binder, characterized in that the positive electrode binder comprises a binder matrix and a positive electrode additive dispersed in the binder matrix, wherein the positive electrode additive is the positive electrode additive according to any one of claims 1 to 4 or prepared by the preparation method of the positive electrode additive according to claim 5.
7. The positive electrode binder according to claim 6, wherein the mass ratio of the binder matrix to the microcapsule repair agent to the initiator is 90 to 99:0.5 to 5:0.5 to 5.
8. A lithium-rich positive electrode comprising a lithium-rich positive electrode material, a conductive agent and a binder, wherein the binder is the positive electrode binder of claim 6 or 7.
9. The lithium-rich cathode according to claim 8, wherein the lithium-rich cathode material comprises a cathode active material and a lithium supplement material, and the mass ratio of the lithium-rich cathode material to the conductive agent to the cathode binder is 80-95: 0.2 to 20:0.5 to 20.
10. A secondary battery comprising a positive electrode, a negative electrode, and a separator stacked between the positive electrode and the negative electrode, wherein the positive electrode is the lithium-rich positive electrode according to claim 8 or 9.
CN202210801275.XA 2022-07-08 2022-07-08 Positive electrode additive and preparation method and application thereof Pending CN115347188A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117080449A (en) * 2023-10-16 2023-11-17 瑞浦兰钧能源股份有限公司 Self-repairing binder for battery and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117080449A (en) * 2023-10-16 2023-11-17 瑞浦兰钧能源股份有限公司 Self-repairing binder for battery and preparation method thereof
CN117080449B (en) * 2023-10-16 2024-02-06 瑞浦兰钧能源股份有限公司 Self-repairing binder for battery and preparation method thereof

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