CN114122368A - Lithium supplement material, manufacturing method thereof, negative pole piece and battery - Google Patents

Lithium supplement material, manufacturing method thereof, negative pole piece and battery Download PDF

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Publication number
CN114122368A
CN114122368A CN202010889337.8A CN202010889337A CN114122368A CN 114122368 A CN114122368 A CN 114122368A CN 202010889337 A CN202010889337 A CN 202010889337A CN 114122368 A CN114122368 A CN 114122368A
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lithium
organic matter
supplement material
battery
ion battery
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肖晶
刘秦
田志明
姜熙
潘仪
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BYD Co Ltd
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BYD Co Ltd
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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
    • H01M4/36—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
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • 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
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M4/04—Processes of manufacture in general
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention discloses a lithium supplement material and a manufacturing method thereof, a negative pole piece and a battery, wherein the lithium supplement material is a composite material with a core-shell structure, the composite material comprises metal lithium particles and an organic matter wrapping the metal lithium particles, the organic matter is in a solid state at the temperature of below 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to a lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery. According to the embodiment of the invention, the active lithium is coated by the organic matter, so that the active lithium stably exists in the preparation process of the pole piece, is slowly released in the circulation process of adding the electrolyte and the battery, and when the organic coating is slowly dissolved in the electrolyte, and the lithium powder participates in the lithium embedding process of the negative electrode, pores are left at the position of the original lithium powder coating, so that the lithium supplementing material not only can provide a lithium source for the negative electrode, but also can improve the porosity, and is beneficial to the exertion of the subsequent multiplying power and the circulation performance.

Description

Lithium supplement material, manufacturing method thereof, negative pole piece and battery
Technical Field
The invention relates to the technical field of batteries, in particular to a lithium supplement material and a manufacturing method thereof, a negative pole piece and a battery.
Background
The lithium ion battery has the advantages of high energy power density, excellent cycle stability, high working voltage, good safety, environmental friendliness and the like, is widely applied to various mobile electronic devices, and gradually becomes a main power source of Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV). The performance of the anode and cathode materials, the electrolyte and the diaphragm influences and restricts the improvement of the performance of the lithium ion battery, wherein the anode material plays a key role. However, the high specific volume negative electrode material of the lithium ion battery forms a Solid Electrolyte Interface (SEI) film during the first charging and overcharging, and consumes a large amount of active lithium ions, thereby causing the loss of irreversible lithium ions and reducing the first charging and discharging efficiency of the battery. In order to improve the first charge and discharge efficiency, researchers of FMC company propose that metal lithium powder is added into a lithium ion battery, and the metal lithium powder is dissolved in a battery system to release a large amount of lithium ions so as to compensate the lithium ions consumed by the battery due to the formation of an SEI film in the first charge and discharge process. The results show that the method achieves obvious effects. Therefore, lithium supplement is an effective method for improving the first charge-discharge efficiency and cycle performance of the battery.
At present, methods for implementing lithium supplement can be mainly divided into the following methods: 1) and in-situ doping and lithium supplementing, namely mixing metal lithium powder with a negative electrode material, a bonding agent, conductive carbon and a solvent to form slurry, and coating the slurry on a copper foil to form an electrode so as to supplement lithium. 2) Connecting a pre-lithiation electrode with lithium metal and then inserting the pre-lithiation electrode into an electrolyte containing lithium salt or directly assembling a primary battery element to embed lithium in the electrolyte by adopting a two-electrode mode; this prelithiation process is primarily carried out in a liquid electrolyte and may therefore also be referred to as a "liquid phase prelithiation process".
However, both methods have their own limitations, which makes commercial application difficult. For the in-situ doping lithium supplement method, the method has extremely strict requirements on the process level and the environmental conditions, high cost and great potential safety hazard due to the extremely high activity of the metal lithium powder. There has been little research in the industry on this approach. For an electrochemical lithium supplement method, lithium is easily inserted into a negative electrode in a transition manner, so that lithium dendrite is formed on the surface of the electrode, and great potential safety hazard is brought.
Disclosure of Invention
The present invention has been made to solve at least one of the above problems. Specifically, the invention provides a lithium supplement material for a lithium ion battery, wherein the lithium supplement material is a composite material with a core-shell structure, the composite material comprises metal lithium particles and an organic matter wrapping the metal lithium particles, the organic matter is in a solid state at a temperature below 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to the lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery.
In an embodiment of the invention, the coating thickness of the organic material is 10-200 nm.
In an embodiment of the present invention, the particle size of the lithium metal particles is 200nm to 10 um.
In an embodiment of the invention, a mass ratio of the lithium metal particles to the organic material is 1:1 to 1: 100.
In an embodiment of the present invention, the organic substance includes an organic ester, an acid anhydride, or an ether.
In an embodiment of the present invention, the organic substance includes at least one of p-methyl benzenesulfonyl isocyanate, propylene sulfate, diphenyl carbonate, propylene sulfonic acid lactone, propenyl-1, 3 sultone, triphenyl phosphate, triphenyl phosphite, and sulfolane.
In another aspect of the present invention, there is provided a method for manufacturing a lithium supplement material for a lithium ion battery according to the present invention, comprising uniformly dispersing metallic lithium powder in a molten organic substance under an inert gas environment to form a mixed solution, filtering the mixed solution, cooling in liquid nitrogen to obtain organic solid particles coated with metallic lithium particles of a certain size,
the organic matter is in a solid state below 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to a lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery.
In an embodiment of the present invention, the mixed solution is filtered through a screen, and the aperture of the screen is 50nm to 20 um.
The invention provides a negative pole piece, which comprises a current collector, a negative active material, a conductive agent, a binder and a lithium supplement material, wherein the negative active material, the conductive agent, the binder and the lithium supplement material are arranged on the current collector.
In yet another aspect, the invention provides a battery comprising a negative electrode plate according to an embodiment of the invention, a positive electrode plate, and a separator disposed between the positive electrode plate and the negative electrode plate.
According to the lithium supplement material and the manufacturing method thereof, the negative pole piece and the battery provided by the invention, the active lithium is coated by the organic matter, so that the active lithium stably exists in the preparation process of the pole piece and is slowly released in the circulation process of adding the electrolyte and the battery, and after the electrolyte is added, the organic coating is slowly dissolved in the electrolyte, and the lithium powder participates in the lithium embedding process of the negative pole, pores are left at the position of the original lithium powder coating, so that the lithium supplement material not only can provide a lithium source for the negative pole, but also can improve the porosity, and is beneficial to the exertion of the subsequent multiplying power and the circulation performance. In addition, the preparation process of the lithium supplement material is simple, safe and low in cost.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
Fig. 1 shows an electron micrograph of a lithium supplement material according to an embodiment of the present invention.
Detailed Description
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order to avoid obscuring the invention.
It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity to indicate like elements throughout.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In order to provide a thorough understanding of the present invention, a detailed structure will be set forth in the following description in order to explain the present invention. Alternative embodiments of the invention are described in detail below, however, the invention may be practiced in other embodiments that depart from these specific details.
Both previous methods of lithium replenishment have their limitations, which make their commercial use difficult. For the in-situ doping lithium supplement method, the method has extremely strict requirements on the process level and the environmental conditions, high cost and great potential safety hazard due to the extremely high activity of the metal lithium powder. There has been little research in the industry on this approach. For an electrochemical lithium supplement method, lithium is easily inserted into a negative electrode in a transition manner, so that lithium dendrite is formed on the surface of the electrode, and great potential safety hazard is brought.
The invention provides a lithium supplement material and a manufacturing method thereof based on the lithium supplement material, so as to overcome the defects.
The invention provides a lithium supplement material for a lithium ion battery, which is a composite material with a core-shell structure, wherein the composite material comprises metal lithium particles and an organic matter wrapping the metal lithium particles, the organic matter is in a solid state at the temperature of below 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to the lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery. In other words, the lithium supplement material of the invention coats the metal lithium particles through the organic matter, and the organic matter coating effectively prevents the lithium from reacting with the air in the preparation process of the pole piece, thereby reducing the requirements on the process level and the environmental conditions, reducing the cost and reducing the potential safety hazard. And because the organic matter is solid below 80 ℃ and has proper melting point and boiling point, the organic matter can be prevented from being volatilized and decomposed in the coating process and the drying process, and after the battery is injected with liquid, the organic matter has the self-affinity of the electrolyte and is dissolved into the electrolyte to release active lithium, so that the lithium supplement is realized, and the first charge-discharge efficiency and the cycle performance of the battery are improved. In addition, in the embodiment of the invention, the organic matter is a small molecular organic matter, has certain reaction activity relative to polymers and the like, and can participate in internal reactions of the lithium ion battery, such as the formation of an SEI film, thereby improving the performance of the battery.
In the embodiment of the present invention, in order to enable the organic substance to coat/wrap the lithium metal particles, it is preferable that the specific surface area of the organic substance is greater than the specific surface area of the lithium metal particles, that is, the specific surface area of the organic substance/the specific surface area of the lithium metal particles is greater than or equal to 1, which is more favorable for coating the lithium metal particles with the organic substance.
In the embodiment of the invention, the organic matter is an organic matter which is mutually soluble with the electrolyte of the lithium ion battery, and the organic matter can be selected according to the electrolyte adopted by the lithium ion battery. In the present embodiment, examples of usable organic substances are given for an electrolyte of a commonly used lithium ion battery, such as organic esters, acid anhydrides, nitriles, and ethers that can be dissolved in the electrolyte of the lithium ion battery, including at least one of p-methyl benzenesulfonyl isocyanate, propylene sulfate, diphenyl carbonate, propylene sulfonic acid lactone, propenyl-1, 3 sultone, triphenyl phosphate, triphenyl phosphite, and sulfolane, for example. It should be understood that the selection of the organic substance is related to the specific electrolyte used, and the organic substance is not limited to the above-given examples, and the organic substance is capable of being dissolved in the electrolyte of the lithium ion battery, and is solid below 80 ℃, and has a proper melting point and boiling point to ensure that the organic substance is not volatilized and not decomposed in the coating process and the drying process.
Further, the organic substance is a commonly used electrolyte additive, and when the organic substance is dissolved in the electrolyte of the lithium ion battery, the organic substance participates in the formation of an SEI film (solid dielectric film) of the lithium ion battery, which is helpful for improving the performance of the lithium ion battery.
Illustratively, in an embodiment of the present invention, the coating thickness of the organic material is 10-200 nm. In the embodiment, the coating thickness of the organic matter is limited to 10-200nm, on one hand, the thickness can ensure that the metal lithium particles do not react with water and oxygen in the environment in the manufacturing process of the pole piece, and on the other hand, the coating thickness ensures that the release of the metal lithium particles is a slow process after the electrolyte is added into the battery, so that the instability of an SEI structure caused by the fact that lithium powder is exposed to the electrolyte in a large amount in a short time is avoided. It is understood that the coating thickness of the organic matter is related to a mass ratio of the organic matter to the lithium particles, the larger the coating thickness, and exemplarily, the coating thickness of the organic matter may be 10nm, 50nm, 80nm, 120nm, 160nm, or 200 nm.
Illustratively, in one embodiment of the present invention, the particle size of the lithium metal particles is 200nm to 10um, which is more beneficial for industrial implementation. Illustratively, the particle size of the lithium metal particles is 200nm, 500nm, 1um, 5um, 8um, or 10 um.
Illustratively, in an embodiment of the present invention, the mass ratio of the metal lithium particles to the organic substance is 1:1 to 1:100, which ensures that the organic substance can completely cover the metal lithium particles, and makes the organic substance have a thickness that makes the metal lithium particles not exposed to the electrolyte immediately after the lithium ion battery is added with the electrolyte, but slowly released during the battery cycle.
The lithium supplement material for the lithium ion battery provided by the embodiment of the invention has the following advantages: firstly, because the active lithium is added in a solid form in the preparation process of the slurry, the active lithium exists stably in a solid form in the baking and rolling processes of the pole piece, and the stability of the active lithium is ensured. And secondly, because the lithium supplement material has electrolyte self-affinity (is mutually soluble with the electrolyte), the lithium supplement material can be dissolved into the electrolyte after the battery is injected with the electrolyte, on one hand, active lithium is released, on the other hand, a new pore channel beneficial to the transmission of the electrolyte is brought, and the full play of the energy density and the power density of the high-surface-density electrode is ensured.
Another aspect of the present invention provides a method for manufacturing a lithium supplement material for a lithium ion battery according to an embodiment of the present invention, including:
firstly, uniformly dispersing metallic lithium powder in a molten organic matter under an inert gas environment to form a mixed solution.
Illustratively, in embodiments of the present invention, the inert gas comprises nitrogen, argon or helium.
The organic matter is small molecular organic ester, acid anhydride, nitrile and ether which can be dissolved in the electrolyte of the lithium ion battery. Illustratively, the organic matter includes at least one of p-methyl benzenesulfonyl isocyanate, propylene sulfate, diphenyl carbonate, propylene sultone, propenyl-1, 3 sultone, triphenyl phosphate, triphenyl phosphite, and sulfolane. Illustratively, the molecular weight of the organic substance is 50 to 400.
Illustratively, in the embodiment of the invention, the organic matter chamber is solid below 80 ℃, and has a proper melting point and a proper boiling point, so that the organic matter chamber is not volatilized and does not decompose in the coating process and the drying process.
And then, filtering the mixed solution, pouring the filtered mixed solution into liquid nitrogen, and cooling to obtain organic solid particles wrapped with the metal lithium particles in a certain size.
Illustratively, the mixed solution is filtered and poured into liquid nitrogen through a screen mesh, and the screen mesh acts to obtain a lithium powder coating with small size (equivalent to the aperture of the screen mesh) (without the screen mesh, the lithium powder and organic matter will be condensed into a whole block after cooling), and illustratively, in one embodiment of the invention, the aperture of the screen mesh is 50nm to 20um, such as 50nm, 100nm, 500nm, 1um, 5um, 10um, 15um, 20um and other suitable values.
Illustratively, in the embodiment of the invention, the coating thickness of the organic matter is 10-200 nm.
Illustratively, in the embodiment of the present invention, the particle size of the lithium metal particles is 200nm to 10um, and the specific surface area of the organic substance is larger than that of the lithium metal particles. Illustratively, in the embodiment of the present invention, the mass ratio of the lithium metal particles to the organic substance is 1:1 to 1: 100.
The lithium supplement material for the lithium ion battery and the manufacturing method thereof have the following advantages that:
the high-dispersion lithium supplement material for the lithium ion battery has the characteristics of simple preparation method and process, safety and stability, and can obviously improve the first charge-discharge efficiency of the lithium ion battery and the cycle performance of the battery.
And secondly, the self-affinity organic molecules of the electrolyte are adopted, so that the active lithium is easily released after the electrolyte is added, and meanwhile, a new pore channel is generated, which is beneficial to the transmission of the electrolyte and the multiplying power performance of the battery.
And thirdly, the selection of the electrolyte self-affinity pore-forming agent avoids the risk of introducing impurities into the conventional inorganic pore-forming agent.
Examples of lithium supplement materials according to embodiments of the present invention and comparative examples are described below to illustrate the characteristics and advantages of lithium supplement materials according to embodiments of the present invention.
Example 1
Adding 10g of lithium powder (with the particle size of 200-500 nm) into 100ml of molten vinyl sulfate in a nitrogen environment (the mass ratio of the lithium powder to the vinyl sulfate is 1: 10), stirring for 2h, then pouring into liquid nitrogen covered with a 10-micron-aperture screen, and cooling for 2h to obtain a lithium supplement material M1. And adding a lithium supplement material M1 into the negative electrode slurry to obtain a battery A, wherein the lithium supplement material M1 accounts for 1% of the total active substances (one or more of natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microbeads, nano carbon, carbon fibers, silicon-based materials, tin-based materials and lithium titanate) of the negative electrode by mass. Fig. 1 shows an electron micrograph of a lithium supplement material M1 of example 1. In the embodiment of the invention, the lithium supplement material is stable in air because of the coating of the organic matter.
Example 2
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the organic matter is methylene methane disulfonate, and a lithium supplement material M2 is obtained. The lithium supplement material M2 was added to the negative electrode slurry to obtain battery B.
Example 3
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the organic matter is propenyl-1, 3 sultone, and the lithium supplement material M3 is obtained. The lithium supplement material M3 was added to the negative electrode slurry to obtain battery C.
Example 4
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the particle size of the lithium powder is 2-5um, a lithium supplement material M4 is obtained, and the lithium supplement material M4 is added into the negative electrode slurry, so that the battery D is obtained.
Example 5
A lithium-supplement material was prepared by the same procedure as in example 1, except that: and (3) obtaining a lithium supplement material M5 by the particle size of the lithium powder being 5-10um, and adding the lithium supplement material M5 into the negative electrode slurry to obtain the battery E.
Example 6
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the mass ratio of the lithium powder to the vinyl sulfate is 1: 50, obtaining a lithium supplement material M6, and adding the lithium supplement material M6 into the negative electrode slurry to obtain a battery F.
Example 7
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the mass ratio of the lithium powder to the vinyl sulfate is 1:100 to obtain a lithium supplement material M7, and adding the lithium supplement material M6 into the negative electrode slurry to obtain a battery G.
Example 8
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the amount of the active material M1 added was 5% based on the total negative electrode active material, to obtain a battery H.
Example 9
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the amount of the active material M1 added was 10% based on the total negative electrode active material content, to obtain a battery I.
Comparative example 1
And (4) adding no lithium supplement material into the lithium ion battery to obtain a battery J.
Comparative example 2
A lithium-supplement material was prepared by the same procedure as in example 1, except that: and (3) obtaining a lithium supplement material M8 by taking polymethyl methacrylate-propylene sulfite block copolymer as an organic matter, and adding the lithium supplement material M8 into the negative electrode slurry to obtain the battery K.
Comparative example 3
A lithium-supplement material was prepared by the same procedure as in example 1, except that: the organic matter was ethylene carbonate (melting point: 35 ℃), and a lithium supplement material M9 was obtained, and a lithium supplement material M9 was added to the negative electrode slurry to obtain a battery L.
In the above examples and comparative examples, the components and weight percentages of the positive electrode slurry of the lithium ion battery are as follows: the content of the anode active material (ternary material (NCM or NCA) or lithium iron phosphate material) is 80-96 percent; the conductive agent comprises but is not limited to SP, carbon nano tube and graphene, and the content is 0.5-6.0%; the binder is, for example, PVDF and is present in an amount of 0.5% to 5.0%.
The components and weight percentages of the negative electrode slurry are as follows: the negative active material is one or more of natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microbeads, nano carbon, carbon fibers, silicon-based materials, tin-based materials and lithium titanate, and the content of the negative active material is 80-96%; the conductive agent comprises, but is not limited to, sp, acetylene black and ketjen black, and the content is 0.5-6.0%; water-soluble thickener CMC (poly hydroxymethyl cellulose) with content of 0.5-5.0%; water-soluble binder SBR (styrene butadiene rubber) with the content of 0.5 to 5.0 percent; and one of the lithium supplement materials B1-B4 with the content of 0.1-10 percent.
The diaphragm mainly comprises a polyolefin diaphragm mainly comprising a Polyethylene (PE) film and a polypropylene (PP) film, and a diaphragm derived from the PE film and the PP film and formed by adding a ceramic layer on the surface of the polyolefin diaphragm.
The electrolyte is a mixed solution of electrolyte lithium salt and a carbonate organic solvent, the electrolyte lithium salt is selected from lithium hexafluorophosphate (LiPF6), the solvent is selected from a mixed solvent of chain carbonate and cyclic carbonate, wherein the chain is at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), Ethyl Methyl Carbonate (EMC) or other chain organic esters containing unsaturated bonds, and the cyclic carbonate can be at least one of Ethylene Carbonate (EC), Propylene Carbonate (PC), Vinylene Carbonate (VC) and other cyclic organic esters containing unsaturated bonds.
The electrode plate and the battery are manufactured by a method commonly used in the field, and are not described in detail herein.
The performance test process and test results of the lithium ion battery are as follows:
normal temperature 100-cycle test of lithium ion battery
(1) In an environment of 25 ℃, the lithium ion battery is discharged to a voltage of 2.0V (lithium iron phosphate, ternary material is discharged to 2.5V) at 0.1C (namely, the current value of theoretical capacity is completely discharged within 10 h), then the lithium ion battery is kept stand for 5min, and the test is started. The test process is as follows: charging the lithium ion battery to 3.8V (lithium iron phosphate, ternary material charging to 4.2V) at a constant current of 1C, charging to 0.05C at a constant voltage of 3.8V, and standing for 5 min; and then discharging the lithium ion battery at a constant current of 1C until the voltage is 2.0V (lithium iron phosphate, the ternary material is discharged to 2.5V), wherein the discharge capacity at the moment is taken as the discharge capacity of the first cycle. The lithium ion battery was subjected to 100 cycles of charge and discharge tests as described above.
(2) High temperature 100 cycle testing of lithium ion batteries
In an environment of 60 ℃, the lithium ion battery is discharged to a voltage of 2.0V (lithium iron phosphate, ternary material is discharged to 2.5V) at 0.1C (namely, the current value of theoretical capacity is completely discharged within 1 h), then the lithium ion battery is kept stand for 5min, and the test is started. The test process is as follows: charging the lithium ion battery to 3.8V (lithium iron phosphate, ternary material charging to 4.2V) at a constant current of 1C, charging to 0.05C at a constant voltage of 3.8V, and standing for 5 min; then, the lithium ion battery was discharged at a constant current of 1C to a voltage of 2.0V, and the discharge capacity at this time was taken as the discharge capacity of the first cycle. The lithium ion battery was subjected to 100 cycles of charge and discharge tests as described above.
The capacity retention ratio of the lithium ion battery after 100 cycles at 20 ℃ and 60 ℃ is (discharge capacity after 100 cycles/first cycle discharge capacity) × 100%.
The first charge-discharge efficiency and the capacity retention rate after 100 cycles of the a-L batteries of the protocol numbers are shown in table 1. The cell data shown are the average of at least 5 parallel cell test results. The table shows that the lithium supplement material can effectively improve the first charge-discharge efficiency and the cycle performance of the battery.
TABLE 1
Figure BDA0002656460540000101
As can be seen from table 1, the first coulombic efficiency and the 100-cycle capacity retention rate of the battery are greatly improved after the lithium supplement material according to the embodiment of the present invention is added.
The invention also provides a negative pole piece for the battery, which comprises a negative active material, a conductive agent, a binder and the lithium supplement material according to the embodiment of the invention.
Illustratively, the negative active material is one or more of natural graphite, artificial graphite, soft carbon, hard carbon, mesocarbon microbeads, nano carbon, carbon fibers, silicon-based materials, tin-based materials and lithium titanate, and the content of the negative active material is 80-96%; the conductive agent comprises, but is not limited to, sp, acetylene black and ketjen black, and the content is 0.5-6.0%; water-soluble thickener CMC (poly hydroxymethyl cellulose) with content of 0.5-5.0%; water-soluble binder SBR (styrene butadiene rubber) with the content of 0.5 to 5.0 percent; and one of the lithium supplement materials B1-B4 with the content of 0.1-10 percent.
Illustratively, the negative electrode plate further comprises a current collector, and the negative active material, the conductive agent, the binder and the lithium supplement material according to the embodiment of the invention are arranged on the current collector.
Specifically, for example, the negative electrode active material, the conductive agent, the binder and the lithium supplement material according to the embodiment of the invention are prepared into slurry, then the slurry is coated on a current collector, then the solvent in the slurry is removed through high-temperature evaporation, and the negative electrode plate is obtained through rolling and slicing. The current collector is, for example, a copper foil.
The negative pole piece provided by the invention adopts the lithium supplement material according to the embodiment of the invention, so that the negative pole piece has similar advantages of capability of improving the first coulombic efficiency and the cycle performance of the battery, safety and stability in air, environmental friendliness, simple and easy realization of a synthesis process and low cost.
The invention further provides a battery, which comprises the negative pole piece, the positive pole piece, the diaphragm arranged between the positive pole piece and the negative pole piece and electrolyte.
The battery provided by the embodiment of the invention adopts the lithium supplement material provided by the embodiment of the invention, so that the battery has similar advantages that the first coulombic efficiency and the cycle performance of the battery can be improved, and the battery has the advantages of safety and stability in air, environmental friendliness, simple and easily realized synthesis process and low cost.
Although the illustrative embodiments have been described herein with reference to the accompanying drawings, it is to be understood that the foregoing illustrative embodiments are merely exemplary and are not intended to limit the scope of the invention thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present invention. All such changes and modifications are intended to be included within the scope of the present invention as set forth in the appended claims.
In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the invention and aiding in the understanding of one or more of the various inventive aspects. However, the method of the present invention should not be construed to reflect the intent: that the invention as claimed requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.
It will be understood by those skilled in the art that all of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where such features are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.
It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.

Claims (10)

1. The lithium supplement material for the lithium ion battery is characterized by being a composite material with a core-shell structure, wherein the composite material comprises metal lithium particles and an organic matter wrapping the metal lithium particles, the organic matter is in a solid state at the temperature of 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to the lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery.
2. The lithium supplement material of claim 1, wherein the organic coating has a thickness of 10-200 nm.
3. The lithium supplement material according to claim 1, wherein the metallic lithium particles have a particle size of 200nm to 10 um.
4. The lithium supplement material according to claim 1, wherein the mass ratio of the metallic lithium particles to the organic matter is 1:1 to 1: 100.
5. The lithium supplement material of claim 1, wherein the organic substance comprises an organic ester, an anhydride, or an ether.
6. The lithium supplement material of claim 5, wherein the organic material comprises at least one of p-methyl benzenesulfonyl isocyanate, propylene sulfate, diphenyl carbonate, propylene sultone, propenyl-1, 3 sultone, triphenyl phosphate, triphenyl phosphite, and sulfolane.
7. A method for making the lithium supplement material of any one of claims 1-6, comprising:
uniformly dispersing metal lithium powder in a molten organic matter under an inert gas environment to form a mixed solution;
filtering the mixed solution, cooling in liquid nitrogen to obtain organic solid particles wrapped with metal lithium particles with certain size,
the organic matter is in a solid state below 80 ℃, the molecular weight of the organic matter is 50-400, and when the lithium supplement material is applied to a lithium ion battery, the organic matter can be dissolved in electrolyte of the lithium ion battery.
8. The method of claim 7, wherein the mixed liquor is filtered through a screen having a pore size of 50nm to 20 um.
9. A negative electrode plate, which is characterized by comprising a current collector, and a negative active material, a conductive agent, a binder and the lithium supplement material of any one of claims 1 to 6 which are arranged on the current collector.
10. A battery, comprising: the negative electrode tab of claim 9, a positive electrode tab, and a separator disposed between the positive and negative electrode tabs.
CN202010889337.8A 2020-08-28 2020-08-28 Lithium supplement material, manufacturing method thereof, negative pole piece and battery Pending CN114122368A (en)

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