CN113013398A - Stabilized lithium powder and preparation method thereof, pre-lithiation process of negative plate, negative plate and lithium ion battery - Google Patents

Stabilized lithium powder and preparation method thereof, pre-lithiation process of negative plate, negative plate and lithium ion battery Download PDF

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CN113013398A
CN113013398A CN202110199145.9A CN202110199145A CN113013398A CN 113013398 A CN113013398 A CN 113013398A CN 202110199145 A CN202110199145 A CN 202110199145A CN 113013398 A CN113013398 A CN 113013398A
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lithium
stabilized
powder
coating layer
fluoride coating
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赵育松
邱昭政
李文龙
梁世硕
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Kunshan Bao Innovative Energy Technology Co Ltd
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Kunshan Bao Innovative Energy Technology 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • 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

Abstract

A stabilized lithium powder and a preparation method thereof, a pre-lithiation process of a negative plate, the negative plate and a lithium ion battery belong to the technical field of batteries. The stabilized lithium powder comprises a metal lithium core and a lithium fluoride coating layer coated on the surface of the metal lithium core, the content of the metal lithium core in the stabilized lithium powder is more than or equal to 98 wt%, and the thickness of the lithium fluoride coating layer is 10-50 nm. The pre-lithiation process of the negative plate comprises the following steps: and carrying out pre-lithiation on the negative plate by adopting stabilized lithium powder, and crushing the lithium fluoride coating layer under the action of pressure. The stabilized lithium powder provided by the embodiment of the application is not easy to react with oxygen and moisture in the air, the safety is high during pre-lithiation, and the first efficiency of the lithium ion battery can be improved after the stabilized lithium powder is adopted to pre-lithiate a negative electrode.

Description

Stabilized lithium powder and preparation method thereof, pre-lithiation process of negative plate, negative plate and lithium ion battery
Technical Field
The application relates to the technical field of batteries, in particular to stabilized lithium powder and a preparation method thereof, a pre-lithiation process of a negative plate, the negative plate and a lithium ion battery.
Background
The lithium ion battery has the characteristics of high energy density, large specific power, good cycle performance, no memory effect, no pollution and the like, has good economic benefit, social benefit and strategic significance, and becomes the most attractive green chemical power source at present.
The Si material has high specific capacity, but the volume of the Si material is greatly expanded in the lithium intercalation process, which not only can damage the structure of an electrode and cause problems of material falling and the like, but also can lead to the cracking of an SE1 film formed on the surface of Si particles and the continuous decomposition of the electrolyte. In order to solve the problem of the volume expansion of Si materials, methods such as nanocrystallization, Si-graphite compounding and SiO material synthesis are developed. From the current market position, SiOx is the most mature high-capacity Si-based negative electrode material and has been used in actual production on a large scale, but it still faces the problem of too low efficiency for the first time, mainly due to the unique crystal structure of SiOx material. And the pre-lithiation of the negative plate can improve the first efficiency, reduce the loss of the lithium ions of the positive electrode and prolong the cycle life of a silica system.
In the prior art, the pre-lithiation is generally performed by lithium powder, but the lithium powder is easy to react with oxygen and moisture in the air to explode during the use process.
Disclosure of Invention
The application provides a stabilized lithium powder and a preparation method thereof, a pre-lithiation process of a negative plate, the negative plate and a lithium ion battery.
The embodiment of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a stabilized lithium powder, which includes a lithium metal core and a lithium fluoride coating layer coated on a surface of the lithium metal core, where a content of the lithium metal core in the stabilized lithium powder is greater than or equal to 98% by weight, and a thickness of the lithium fluoride coating layer is 10 to 50 nm.
In a second aspect, embodiments of the present application provide a method for preparing a stabilized lithium powder of an embodiment of the first aspect, including:
a lithium fluoride coating layer is formed on the metallic lithium core by reacting a fluorine source with the surface of the metallic lithium core.
In a third aspect, an embodiment of the present application provides a prelithiation process for a negative electrode sheet, which includes: the stabilized lithium powder of the first aspect example was used to prelithiate the negative plate and the lithium fluoride coating layer was crushed under pressure.
In a fourth aspect, embodiments of the present application provide a pole piece, which is prepared by the pre-lithiation process of the negative pole piece of the embodiment of the third aspect.
In a fifth aspect, embodiments of the present application provide a lithium ion battery, which includes a negative electrode sheet manufactured by the negative electrode sheet manufacturing process of the fourth aspect of the present application.
The stabilized lithium powder and the preparation method thereof, the pre-lithiation process of the negative plate, and the positive plate and the lithium ion battery have the beneficial effects that:
in the stabilized lithium powder of this application, lithium fluoride coating cladding can separation metal lithium nuclear and air contact on the surface of metal lithium nuclear, and stabilized lithium powder is difficult to react with oxygen and moisture in the air, and the security is high during lithiation in advance. The content of metal lithium nuclei of the stabilized lithium powder is more than or equal to 98 wt%, the lithium content of the stabilized lithium powder is high, and the first efficiency of the lithium ion battery can be remarkably improved after the stabilized lithium powder is adopted for pre-lithiation.
In addition, the applicant finds in research that the effect of prelithiation can be achieved only by crushing the lithium fluoride coating layer after the lithium fluoride coating layer is prelithiated to the negative plate by using the stabilized lithium powder, if the thickness of the lithium fluoride coating layer is too thick, more lithium sources are required to be added to ensure that the content of metal lithium nuclei of the stabilized lithium powder is more than or equal to 98 wt% so as to ensure the first efficiency of the lithium ion battery, the addition of excessive lithium sources aggravates the side reaction on the surface of the negative plate to cause the performance deterioration of the battery, and the excessive lithium metals can form lithium dendrites due to incomplete consumption in the charging and discharging process, so that the electrical performance and the safety performance of the battery are affected, and the addition of excessive lithium sources increases the cost; if the thickness of the lithium fluoride coating layer is too thin, the lithium metal core is easily exposed in the pre-lithiation process, which causes a safety hazard. The thickness of the lithium fluoride coating layer of the stabilized lithium powder provided by the embodiment of the application is 10-50 nm, and the thickness is appropriate, so that the overall performance of the battery can be guaranteed, and the safety during pre-lithiation can be guaranteed.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
Fig. 1 is a schematic structural view of an apparatus for preparing stabilized lithium powder according to an embodiment of the present disclosure;
FIG. 2 is an SEM image of a stabilized lithium powder of example 1 of the present application;
FIG. 3 is an XRD pattern of the stabilized lithium powder of example 1 of the present application;
FIG. 4 is an SEM image of the stabilized lithium powder of example 1 of the present application after being pressed by a roller;
fig. 5 is an SEM image of the stabilized lithium powder of comparative example 1 of the present application after being pressed by a roller.
Icon: 11-a pressure pump; 12-a slurry flow meter; 13-a spray head; 14-a cooling tower; 15-gas filter; 16-a blower; 17-a gas heater; 18-a gas flow meter; 19-tail gas treater.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present application and should not be construed as limiting the scope of the present application. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
The pre-lithiation of the negative plate can improve the first efficiency, reduce the loss of the lithium ions of the positive electrode and prolong the cycle life of a silica system. In the prior art, the pre-lithiation is generally performed by lithium powder, but the lithium powder is easy to react with oxygen and moisture in the air to explode during the use process.
Based on the above, the application provides a stabilized lithium powder and a preparation method thereof, a pre-lithiation process of a negative plate, the negative plate and a lithium ion battery.
The stabilized lithium powder and the preparation method thereof, the prelithiation process of the negative electrode sheet, the electrode sheet and the lithium ion battery in the embodiment of the present application are specifically described as follows:
in a first aspect, an embodiment of the present application provides a stabilized lithium powder, which includes a lithium metal core and a lithium fluoride coating layer coated on a surface of the lithium metal core, where a content of the lithium metal core in the stabilized lithium powder is greater than or equal to 98% by weight, and a thickness of the lithium fluoride coating layer is 10 to 50 nm.
In the stabilized lithium powder of this application, lithium fluoride coating cladding can separation metal lithium nuclear and air contact on the surface of metal lithium nuclear, and stabilized lithium powder is difficult to react with oxygen and moisture in the air, and the security is high during lithiation in advance. The inventor of the application discovers in research that the content of the metal lithium nuclei in the stabilized lithium powder has a relatively obvious influence on the first efficiency of the lithium ion battery, wherein the content of the metal lithium nuclei in the stabilized lithium powder is more than or equal to 98 wt%, and the lithium content of the stabilized lithium powder is high.
Illustratively, the lithium metal core content of the stabilized lithium powder is any one of, or a range between any two of, 98% wt, 98.1% wt, 98.2% wt, 98.3% wt, 98.4% wt, 98.5% wt, 98.6% wt, 98.7% wt, 98.8% wt, 99% wt, 99.2% wt, 99.4% wt, and 99.5% wt.
In addition, the applicant finds in research that the effect of prelithiation can be achieved only by crushing the lithium fluoride coating layer after the lithium fluoride coating layer is prelithiated to the negative plate by using the stabilized lithium powder, if the thickness of the lithium fluoride coating layer is too thick, more lithium sources are required to be added to ensure that the content of metal lithium nuclei of the stabilized lithium powder is more than or equal to 98 wt% so as to ensure the first efficiency of the lithium ion battery, the addition of excessive lithium sources aggravates the side reaction on the surface of the negative plate to cause the performance deterioration of the battery, and the excessive lithium metals can form lithium dendrites due to incomplete consumption in the charging and discharging process, so that the electrical performance and the safety performance of the battery are affected, and the addition of excessive lithium sources increases the cost; if the thickness of the lithium fluoride coating layer is too thin, metal lithium nuclei are easily exposed in the pre-lithiation process, thereby causing potential safety hazards. The thickness of the lithium fluoride coating layer is 10-50 nm, and the thickness is suitable, so that the overall performance of the battery can be guaranteed, and the safety during pre-lithiation can be guaranteed.
Illustratively, the lithium fluoride cladding layer has a thickness of any one of 10nm, 17nm, 25nm, 30nm, 38nm, 42nm, 48nm, and 50nm, or a range between any two. Optionally, the thickness of the lithium fluoride coating layer is 10-40 nm, 10-30 nm, 20-40 nm or 20-30 nm.
Further, the inventors of the present application found in their studies that, since the reactivity of the metallic lithium core is high, if the overall particle diameter of the stabilized lithium powder is too small, the specific surface area is too large, which easily causes a safety problem; if the overall particle size of the stabilized lithium powder is too large, the amount added during prelithiation is reduced and cannot be uniformly distributed on the surface of the electrode material of the negative electrode sheet, so that the kinetics of lithium metal ion extraction during prelithiation is deteriorated and the prelithiation effect is affected. Optionally, the particle size of the stabilized lithium powder is 20-100 μm.
The particle size of the stabilized lithium powder in the embodiment of the application is 20-100 mu m, the particle size range is proper, the safety during pre-lithiation can be improved, and the pre-lithiation effect can be better guaranteed. Illustratively, the stabilized lithium powder particle size is any one or a range between any two of 20 μm, 32 μm, 44 μm, 50 μm, 62 μm, 74 μm, 81 μm, 89 μm, and 100 μm. Optionally, the particle size of the stabilized lithium powder is 20-50 μm, 20-40 μm, 25-35 μm, 30-60 μm or 40-80 μm.
In a second aspect, embodiments of the present application provide a method for preparing a stabilized lithium powder of an embodiment of the first aspect, including:
a lithium fluoride coating layer is formed on the metallic lithium core by reacting a fluorine source with the surface of the metallic lithium core.
Wherein the lithium metal core can be prepared by spray granulation of lithium slurry. It is understood that the lithium metal core may be directly formed of lithium powder.
Illustratively, the lithium slurry is subjected to spray granulation to obtain metallic lithium nuclei, and fluorine source gas is introduced to react with the metallic lithium nuclei to form a lithium fluoride coating layer on the surfaces of the metallic lithium nuclei.
The lithium metal core is prepared by a spray granulation mode, the finished product quality is good, and the method is suitable for large-scale production. Through the reaction of the fluorine source gas and the metal lithium nucleus, the fluorine source gas can be contacted with the whole surface of the metal lithium nucleus, so that the reaction is relatively uniform, the formed lithium fluoride coating layer is compact, and the prepared stabilized lithium powder has controllable thickness and relatively uniform particle size. Illustratively, the fluorine source gas includes HF, F2And freon gas. Optionally, the gas purity of the fluorine source gas is greater than or equal to 99.99%.
Illustratively, the lithium slurry is prepared by melting lithium blocks and/or lithium tapes, optionally at a temperature ≧ 250 ℃. Illustratively, the melting process is carried out under the protection of an inert atmosphere or a nitrogen atmosphere, so that lithium can be prevented from being oxidized. Illustratively, the inert atmosphere is argon, helium, or neon. Optionally, the gas purity of the inert atmosphere and the nitrogen atmosphere is more than or equal to 99.99%.
In other embodiments, the stabilized lithium powder may be prepared in other ways, for example, by mixing a fluorine-containing acid salt, a lithium metal core, and an organic solvent to form a lithium fluoride coating layer on the surface of the lithium metal core. Wherein the metal lithium core is lithium powder.
When the preparation of the stabilized lithium powder is a mode of performing spray granulation on lithium slurry to obtain metal lithium nuclei, and introducing fluorine source gas to enable the fluorine source gas to react with the metal lithium nuclei to form a lithium fluoride coating layer on the surface of the metal lithium nuclei, the spray speed of the lithium slurry during spray granulation is 2-20 mL/min, and the flow rate of the fluorine source gas is 10-50 mL/min. Wherein, the flow rate of the fluorine source gas refers to the volume flow rate under normal temperature and normal pressure, and exemplarily, the temperature is 25 ℃ and the pressure is 101 Pa.
The spraying speed of the lithium slurry during spray granulation is 2-20 mL/min, metal lithium nuclei with a proper particle size range can be formed, if the spraying speed of the lithium slurry during spray granulation is too high, the particle size of the metal lithium nuclei is too large, the particle size of the finally formed stabilized lithium powder is too large, and if the spraying speed of the lithium slurry during spray granulation is too low, the particle size of the metal lithium nuclei is too small.
Illustratively, the spray rate of the lithium slurry during spray granulation is in a range of any one or any two of 2mL/min, 5mL/min, 8mL/min, 10mL/min, 12mL/min, 15mL/min, 17mL/min, and 20mL/min, for example, 2.5 to 5 mL/min.
By controlling the flow rate of the fluorine source gas, the contact amount of the fluorine source gas and the lithium powder can be controlled to control the surface reaction, thereby controlling the thickness of the lithium fluoride coating layer. The flow rate of the fluorine source gas is 10-50 mL/min, so that the fluorine source gas and the metal lithium core fully react to form a lithium fluoride coating layer to fully coat the metal lithium core, the lithium fluoride coating layer with uniform thickness is formed, and the thickness of the lithium fluoride coating layer can be within the range of 10-50 nm.
Illustratively, the flow rate of the fluorine source gas is any one of 10mL/min, 20mL/min, 30mL/min, 4mL/min, and 50mL/min or a range between any two.
Referring to fig. 1, an apparatus for preparing stabilized lithium powder illustratively includes a cooling tower 14, a pressure pump 11, a slurry flow meter 12, a gas flow meter 18, a gas heater 17, a blower 16, a gas filter 15, and an exhaust gas processor 19. The inside shower nozzle 13 that is provided with of upper end of cooling tower 14, the discharge end of force pump 11 passes through the thick liquids pipeline and communicates with shower nozzle 13, and thick liquids flowmeter 12 installs on the thick liquids pipeline. The upper side end of the cooling tower 14 is provided with a gas inlet, the bottom end of the cooling tower 14 is provided with a gas outlet, the gas filter 15 is communicated with the gas inlet end of the blower 16, the gas outlet end of the blower 16 is communicated with the gas inlet end of the gas heater 17, the gas outlet end of the gas heater 17 is communicated with the gas inlet of the cooling tower 14 through a gas pipeline, the gas flowmeter 18 is installed on the gas pipeline, and the tail gas processor 19 is communicated with the gas outlet of the cooling tower 14.
Illustratively, when the stabilized lithium powder is prepared by using the above-mentioned apparatus, lithium slurry is pumped to the spray head 13 by the pressure pump 11 to be spray-granulated to form metallic lithium nuclei in the cooling tower 14, and the ejection speed of the lithium slurry can be controlled by adjusting the slurry flow meter 12. Fluorine source gas is filtered by a gas filter 15 and blown into a gas heater 17 for heating through a blower 16, then enters a cooling tower 14 from a gas inlet to react with lithium metal nuclei to form stabilized lithium powder, then the stabilized lithium powder is cooled and dried in the cooling tower 14, and finally redundant fluorine source gas enters a tail gas processor 19 for processing.
In a third aspect, an embodiment of the present application provides a prelithiation process for a negative electrode sheet, which includes: the stabilized lithium powder of the first aspect example was used to prelithiate the negative plate and the lithium fluoride coating layer was broken under the action of mechanical pressure.
In the research of the applicant, the stabilized lithium powder is adopted to pre-lithiate the negative plate, and then the lithium fluoride coating layer needs to be crushed, so that the pre-lithiation effect can be achieved. Illustratively, in the prelithiation process, stabilized lithium powder is dispersed in an organic solvent to obtain a dispersion liquid, then the dispersion liquid is sprayed on the surface of the negative plate, and after drying, the lithium fluoride coating layer is crushed under the action of mechanical pressure, thereby achieving the prelithiation effect.
The thickness of the lithium fluoride coating layer of the stabilized lithium powder provided by the embodiment of the application is 10-50 nm, the thickness of the lithium fluoride coating layer is appropriate, the overall performance of the battery can be guaranteed under the action of mechanical pressure in the process of crushing the lithium fluoride coating layer, and the safety during pre-lithiation can be guaranteed. In addition, the stabilized lithium powder of the embodiment of the application has high lithium content, and after the stabilized lithium powder is adopted for pre-lithiation, the first efficiency of the lithium ion battery can be obviously improved.
For example, the crushing of the lithium fluoride coating layer under pressure may be performed by a roll press, or by a flat press, in which the lithium fluoride coating layer is crushed by pressing with a plate-like object.
In a fourth aspect, embodiments of the present application provide a pole piece, which is prepared by the pre-lithiation process of the negative pole piece of the embodiment of the third aspect. When the pole piece is used in a battery, the first efficiency and the battery capacity of the battery can be obviously improved.
In a fifth aspect, embodiments of the present application provide a lithium ion battery, which includes a negative electrode sheet manufactured by the negative electrode sheet manufacturing process of the fourth aspect of the present application.
The lithium ion battery provided by the embodiment of the application has higher initial efficiency and higher battery capacity.
The stabilized lithium powder and the preparation method thereof, the prelithiation process of the negative electrode sheet, the electrode sheet and the lithium ion battery are further described in detail in the following with reference to the examples.
Example 1
This example provides a stabilized lithium powder, which is prepared by the following steps:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain metal lithium nuclei, wherein the spray speed of the lithium slurry during spray granulation is 2.5mL/min, and then introducing Freon gas at the flow rate of 10mL/min at the temperature of 25 ℃ and under the pressure of 101Pa so that the Freon gas reacts with the metal lithium nuclei to form a lithium fluoride coating layer on the surfaces of the metal lithium nuclei and drying the lithium fluoride coating layer to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 98.2 wt%, and the content of the lithium fluoride coating layer is 1.7 wt%.
Example 2
This example provides a stabilized lithium powder, which is prepared by the following steps:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain the lithium metal core, wherein the spray speed of the lithium slurry during spray granulation is 5 mL/min. Then, freon gas is introduced at the temperature of 25 ℃ and the pressure of 101Pa and at the flow rate of 10mL/min so that the freon gas reacts with the metal lithium nucleus to form a lithium fluoride coating layer on the surface of the metal lithium nucleus, and the lithium fluoride coating layer is dried to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 98.0 wt%, and the content of the lithium fluoride coating layer is 1.9 wt%.
Comparative example 1
The present comparative example provides a stabilized lithium powder, the method of making comprising the steps of:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain the lithium metal core, wherein the spray speed of the lithium slurry during spray granulation is 10 mL/min. Then, freon gas is introduced at the temperature of 25 ℃ and the pressure of 101Pa and at the flow rate of 10mL/min so that the freon gas reacts with the metal lithium nucleus to form a lithium fluoride coating layer on the surface of the metal lithium nucleus, and the lithium fluoride coating layer is dried to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 97.0 wt%, and the content of the lithium fluoride coating layer is 2.2 wt%.
Comparative example 2
The present comparative example provides a stabilized lithium powder, the method of making comprising the steps of:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain the lithium metal core, wherein the spray speed of the lithium slurry during spray granulation is 2.5 mL/min. Then, freon gas is introduced at the temperature of 25 ℃ and the pressure of 101Pa and the flow rate of 30mL/min so that the freon gas reacts with the metal lithium nucleus to form a lithium fluoride coating layer on the surface of the metal lithium nucleus, and the lithium fluoride coating layer is dried to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 97.3 wt%, and the content of the lithium fluoride coating layer is 2.5 wt%.
Comparative example 3
The present comparative example provides a stabilized lithium powder, the method of making comprising the steps of:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain the lithium metal core, wherein the spray speed of the lithium slurry during spray granulation is 2.5 mL/min. Then, freon gas is introduced at the temperature of 25 ℃ and the pressure of 101Pa and the flow rate of 50mL/min so that the freon gas reacts with the metal lithium nucleus to form a lithium fluoride coating layer on the surface of the metal lithium nucleus, and the lithium fluoride coating layer is dried to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 96.1 wt%, and the content of the lithium fluoride coating layer is 3.7 wt%.
Comparative example 4
The present comparative example provides a stabilized lithium powder, the method of making comprising the steps of:
melting 10g of lithium blocks at 250 ℃ under the protection of argon atmosphere to obtain lithium slurry, and stirring during melting, wherein the purity of the lithium blocks is more than or equal to 99.99%.
And carrying out spray granulation on the lithium slurry to obtain the lithium metal core, wherein the spray speed of the lithium slurry during spray granulation is 2.5 mL/min. Then, freon gas is introduced at the temperature of 25 ℃ and the pressure of 101Pa and at the flow rate of 70mL/min so that the freon gas reacts with the metal lithium nucleus to form a lithium fluoride coating layer on the surface of the metal lithium nucleus, and the lithium fluoride coating layer is dried to obtain the stabilized lithium powder. Wherein the content of the metal lithium core in the stabilized lithium powder is 94.6 wt%, and the content of the lithium fluoride coating layer is 5.0 wt%.
Test example 1
The stabilized lithium powders of example 1, example 2 and comparative examples 1 to 4 were all prepared as the stabilized lithium powder: polyvinylidene fluoride (abbreviated as PVDF in english): carbon nanotubes (abbreviated as CNTs in english): n-methylpyrrolidone (NMP) 1.5:2:2:100, and the obtained slurry has an areal density of 11mg/cm2Coating on a copper foil with a thickness of 12 μm and drying and rolling (pressure condition of 12 MPa/m)2) The working electrode was an inert copper foil as the counter electrode, and examples 1 and 2 and comparative examples were usedThe stabilized lithium powders of examples 1 to 4 were prepared into working electrodes, which were assembled into half cells with a counter electrode, respectively, and the counter electrode was charged at a low rate using a charging process step, wherein the charging rate was 0.02C and the cut-off voltage was 2.0V, and then the gram capacity of the half cells was measured, and the results are reported in table 1.
TABLE 1 structural parameters of stabilized lithium powders and corresponding gram capacities of half-cells
Figure BDA0002947356430000111
As can be seen from the results of table 1, the stabilized lithium powders of examples 1 and 2 have a content of the metallic lithium core of 98 wt% or more. Comparing example 1 with comparative examples 2 to 4, it is found that, when the particle size of the stabilized lithium powder is not very different, the content of the metal lithium core in example 1 is greater than 98 wt%, and the content of the lithium fluoride coating layer in example 1 is less than the content of the lithium fluoride coating layers in comparative examples 2 to 4, which means that the thickness of the lithium fluoride coating layer in example 1 is less than the thickness of the lithium fluoride coating layers in comparative examples 2 to 4, and it can be known by combining the gram capacities obtained by the experiment that the effects of the content of the metal lithium core and the thickness of the lithium fluoride coating layer in the stabilized lithium powder in example 1 and example 2 of the present application on the capacity of the battery are better, and then the first efficiency of the battery can be improved after the stabilized lithium powder in example of the present application is used for carrying out the pre.
Test example 2
The stabilized lithium powder obtained in example 1 was observed under an electron scanning microscope, and the SEM image obtained is shown in fig. 2.
As can be seen from fig. 2, the particle size of the stabilized lithium powder obtained in example 1 of the present application was relatively uniform.
Test example 3
The stabilized lithium powder obtained in example 1 was subjected to XRD measurement, and the XRD pattern obtained is shown in fig. 3.
Test example 4
The stabilized lithium powders obtained in example 1 and comparative example 1 were placed under the same pressure (pressure condition of 12 MPa/m)2) Rolling, and scanning electron microscopeThe following observation gave SEM images as shown in FIGS. 4 and 5.
As can be seen from fig. 4 and 5, the lithium fluoride coating layer of the stabilized lithium powder of example 1 broke better than the lithium fluoride coating layer of the stabilized lithium powder of comparative example 1 because the lithium fluoride coating layer of comparative example 1 was thicker than the lithium fluoride coating layer of example 1.
The foregoing is illustrative of the present application and is not to be construed as limiting thereof, as numerous modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (10)

1. The stabilized lithium powder is characterized by comprising a metal lithium core and a lithium fluoride coating layer coated on the surface of the metal lithium core, wherein the content of the metal lithium core in the stabilized lithium powder is more than or equal to 98%, and the thickness of the lithium fluoride coating layer is 10-50 nm.
2. The stabilized lithium powder according to claim 1, wherein the particle size of the stabilized lithium powder is 20 to 100 μm; the particle size of the stabilized lithium powder is 20-50 μm.
3. A method of preparing a stabilized lithium powder according to claim 1 or 2, comprising:
forming the lithium fluoride coating layer on the metallic lithium core by reacting a fluorine source with the surface of the metallic lithium core.
4. The method for preparing the stabilized lithium powder according to claim 3, wherein a lithium slurry is subjected to spray granulation to obtain the metallic lithium core, a fluorine source gas is introduced to react with the metallic lithium core to form the lithium fluoride coating layer on the surface of the metallic lithium core, the spray rate of the lithium slurry during spray granulation is 2-20 mL/min, and the flow rate of the fluorine source gas is 10-50 mL/min.
5. The method for producing a stabilized lithium powder according to claim 4, wherein a spray rate in the spray granulation of the lithium slurry is 2.5 to 5mL/min, and a flow rate of the fluorine source gas is 10 mL/min.
6. The method of claim 4, wherein the fluorine source gas comprises HF, F2And freon gas.
7. A pre-lithiation process of a negative electrode sheet is characterized by comprising the following steps of: the stabilized lithium powder of claim 1 or 2 is used to prelithiate a negative plate, and the lithium fluoride coating layer is crushed under the action of mechanical pressure.
8. The prelithiation process according to claim 7, wherein the lithium fluoride cladding layer is crushed by rolling.
9. A pole piece, characterized in that it is made by the prelithiation process of the negative pole piece according to claim 7 or 8.
10. A lithium ion battery, characterized in that it comprises a pole piece according to claim 9.
CN202110199145.9A 2021-02-22 2021-02-22 Stabilized lithium powder and preparation method thereof, pre-lithiation process of negative plate, negative plate and lithium ion battery Pending CN113013398A (en)

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CN114864873A (en) * 2022-04-20 2022-08-05 江苏正力新能电池技术有限公司 Pre-lithiation method for negative plate, negative plate obtained by pre-lithiation method and secondary battery

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CN107039633A (en) * 2017-03-24 2017-08-11 江苏乐能电池股份有限公司 A kind of energy-density lithium ion battery composite negative pole pole piece and its lithium ion battery
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