CN112028078B - Method for improving stability of lithium battery silicon negative electrode material - Google Patents

Method for improving stability of lithium battery silicon negative electrode material Download PDF

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CN112028078B
CN112028078B CN202010837410.7A CN202010837410A CN112028078B CN 112028078 B CN112028078 B CN 112028078B CN 202010837410 A CN202010837410 A CN 202010837410A CN 112028078 B CN112028078 B CN 112028078B
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lithium
silicon
negative electrode
powder
placing
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CN112028078A (en
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崔大祥
张芳
葛美英
王亚坤
卢玉英
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Shanghai National Engineering Research Center for Nanotechnology Co Ltd
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Shanghai National Engineering Research Center for Nanotechnology Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/21—After-treatment
    • C01B32/22—Intercalation
    • C01B32/225—Expansion; Exfoliation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/04—Halides
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • 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

The invention discloses a method for improving the stability of a lithium battery silicon negative electrode material, which takes nontoxic fluoride as a raw material, decomposes at low temperature to form a fluorine gas phase to react with Li, and uniformly forms a lithium fluoride film on the surface of a silicon negative electrode, wherein the lithium fluoride layer can increase the safety of prelithiation and simultaneously plays a role in chemical stability and reducing the corrosion of electrolyte to a silicon substrate. The invention is suitable for surface treatment with high purity and no toxicity. The powder prepared by the invention can be used in the field of high-performance lithium batteries.

Description

Method for improving stability of lithium battery silicon negative electrode material
Technical Field
The invention belongs to the field of inorganic nonmetallic materials, and particularly relates to a method for improving the stability of a lithium battery silicon-negative electrode material.
Background
Energy storage and conversion technology of fluorine-containing energy materials has become a development trend of research in the field of new energy at present. The unique fluorine effect is utilized to design the fluorine-containing energy material, a new generation of fluorination technology with mild condition, high selectivity and controllable structure is developed, and the fluorination technology is used for efficiently preparing the fluorine-containing energy material. By introducing fluorine element, the efficiency of energy storage and conversion, the safety and the weather resistance of the material are greatly improved, the related internal rules between the structure and the performance of the fluorine-containing energy material are deeply known by combining a new device assembly mode, a series of technical problems of testing, evaluation, application and the like of the fluorine-containing energy material are solved, and a new energy technical system based on the fluorine-containing energy material is developed. Corresponding achievements in scientific research will draw high international attention and lead the development of the next generation of clean energy technology.
The sub-silicon anode is currently the most promising high capacity anode material, but suffers from severe corrosion during electrochemical performance and cycling, and therefore a reliable passivation layer is required on the surface. The method utilizes an in-situ decomposition reaction method to form a compact LiF layer on the surface of the silicon-containing cathode, the LiF coating has excellent chemical stability in a high-reducing environment, extremely low solubility in electrolyte and very strong mechanical property, and can reduce the corrosion reaction between lithium metal and carbonate electrolyte to the maximum extent.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for improving the stability of a silicon-containing negative electrode material of a lithium battery.
The purpose of the invention is realized by the following scheme: the method for improving the stability of the negative electrode material of the silicon-containing lithium battery comprises the steps of forming a lithium fluoride coating on the surface of the silicon-containing lithium battery by a one-step method, decomposing at low temperature by using non-toxic fluoride as a raw material to form a lithium fluoride film with uniform reaction between a gas phase of fluorine and Li on the surface of the silicon-containing negative electrode, and comprising the following steps of:
(1) Mixing the silicon powder and the lithium powder under the protection of argon, wherein the mass percentage of the lithium powder is 0.1-0.9%, and sealing for later use after mixing;
(2) Placing an organic fluoride at the bottom of the crucible, placing a mixture of the inferior silicon and the lithium powder on an upper layer, placing the mixture in the air for not more than 5 minutes, and then placing the mixture in an atmosphere furnace;
(3) Heating to 240-400 ℃, and preserving heat for 1 hour to ensure that the fluorine carbon free radical fully reacts with the lithium metal;
(4) And filtering, cleaning and drying the obtained powder to prepare a half cell for performance evaluation.
The organic fluoride comprises one of polyvinylidene fluoride, polytetrafluoroethylene and perfluoro resin.
And (5) in the step (4), the manufacturing method of the half cell is that the material is used as a positive electrode, a metal lithium sheet is used as a negative electrode, a silicon-carbon special electrolyte is used, a 2325 diaphragm is adopted for assembly, and the assembled cell can be tested after standing for 12 hours.
The invention uses non-toxic organic fluoride as raw material, decomposes at low temperature to form fluorine gas phase to react with Li, and forms a uniform lithium fluoride film layer on the surface of the negative electrode of the silicon, and the lithium fluoride layer can increase the safety of prelithiation, and simultaneously has the functions of chemical stability and reducing the corrosion of electrolyte to a silicon substrate.
The powder prepared by the invention can be used in the field of high-performance lithium batteries.
The present invention proposes to exfoliate graphite by using hydroxyl and oxygen generated by electrode reaction as driving forces. The method has the advantages of simple preparation, short time and strong controllability, and can be used for producing high-quality lithium fluoride-coated silicon material.
Drawings
FIG. 1 is an SEM spectrum of a powder sample obtained in example 1 of the present invention;
fig. 2 is a battery cycle life curve obtained in example 1 of the present invention.
Detailed Description
Example 1
A lithium battery silicon-containing negative electrode material with improved stability comprises a lithium fluoride coating formed on a silicon-containing surface by a one-step method, a non-toxic fluoride is used as a raw material, a gas phase of fluorine formed by decomposing at low temperature is reacted with Li to form a uniform lithium fluoride film on the surface of a silicon-containing negative electrode, and the lithium battery silicon-containing negative electrode material is prepared by the following steps:
(1) Weighing 10g of silicon monoxide powder, mixing with 0.1% of lithium powder under the protection of argon gas, and sealing for later use after mixing;
(2) Placing organic fluoride polyvinylidene fluoride at the bottom of a crucible, placing a mixture of silicon-containing powder and lithium powder on an upper layer, placing the mixture in air for no more than 5 minutes, and then placing the mixture in an atmosphere furnace;
(3) Heating to 240 ℃, and preserving the temperature for 1 hour to ensure that the free fluorocarbon radicals decomposed by the organic matters fully react with the lithium metal;
(4) The obtained powder is filtered, cleaned and dried to be used as a positive electrode, the appearance and EDS are shown in figure 1, a metal lithium sheet is used as a negative electrode, a silicon-carbon special electrolyte is used, a 2325 diaphragm is adopted for assembly, and the assembled battery can be tested after standing for 12 hours. The cycling performance was improved from 80 times to 100 times compared to the uncoated, sub-silicon anode, as shown in fig. 2.
Example 2
A lithium battery silicon-containing negative electrode material with improved stability is prepared by the following steps similar to the example 1:
(1) Weighing 10g of silicon powder, mixing with 0.9% of lithium powder under the protection of argon gas, and sealing for later use after mixing;
(2) Placing polytetrafluoroethylene at the bottom of the crucible, placing a mixture of silicon monoxide and lithium powder on an upper layer, placing the mixture in the air for no more than 5 minutes, and then placing the mixture in an atmosphere furnace;
(3) Heating to 400 ℃, and preserving the temperature for 1 hour to ensure that the free fluorocarbon radicals decomposed by the organic matters fully react with the lithium metal;
(4) The obtained powder is filtered, cleaned and dried to be used as a positive electrode, a metal lithium sheet is used as a negative electrode, a special silicon-carbon electrolyte is used, a 2325 diaphragm is adopted for assembly, and the assembled battery can be tested after standing for 12 hours. The cycling performance was improved from 80 times to 200 times compared to the uncoated, sub-silicon anode.
Example 3
A lithium battery silicon-containing negative electrode material with improved stability is prepared by the following steps similar to the preparation of the embodiment 1:
(1) Weighing 10-silica powder, mixing with 0.5% lithium powder under the protection of argon gas, and sealing for later use;
(2) Placing perfluoro resin at the bottom of the crucible, placing a mixture of the silicon monoxide and the lithium powder on the upper layer, placing the mixture in the air for no more than 5 minutes, and then placing the mixture in an atmosphere furnace;
(3) Heating to 300 ℃, and preserving heat for 1 hour to ensure that the fluorine carbon free radicals decomposed by the organic matter fully react with the lithium metal;
(4) The obtained powder is filtered, cleaned and dried to be used as a positive electrode, a metal lithium sheet is used as a negative electrode, a special silicon-carbon electrolyte is used, a 2325 diaphragm is adopted for assembly, and the assembled battery can be tested after standing for 12 hours. The cycling performance increased from 80 times to 140 times compared to the uncoated, sub-silicon anode.

Claims (2)

1. A method for improving the stability of a lithium battery silicon-negative electrode material comprises a one-step method for forming a lithium fluoride coating on a silicon-negative surface, and is characterized in that non-toxic fluoride is used as a raw material, and is decomposed at low temperature to form a lithium fluoride film with uniform fluorine gas phase reacting with Li on the silicon-negative electrode surface, and the method comprises the following steps:
(1) Mixing the silicon powder and the lithium powder under the protection of argon, wherein the mass percentage of the lithium powder is 0.1-0.9%, and sealing for later use after mixing;
(2) Placing the organofluoride at the bottom of the crucible, placing the mixture of the inferior silicon and the lithium powder on the upper layer, placing the mixture in the air for no more than 5 minutes, and then placing the mixture in an atmosphere furnace;
(3) Heating to 240-400 ℃, and preserving heat for 1 hour to ensure that the fluorine carbon free radical fully reacts with the lithium metal;
(4) Filtering, cleaning and drying the obtained powder, and making the powder into a half cell for performance evaluation; wherein the content of the first and second substances,
the fluorine organic matter comprises one of polyvinylidene fluoride, polytetrafluoroethylene and perfluoro resin.
2. The method of claim 1 for improving the stability of a negative electrode material of a lithium battery comprising: the manufacturing method of the half cell comprises the following steps: and (4) taking the dried powder as a positive electrode, taking a metal lithium sheet as a negative electrode, assembling by using a special silicon-carbon electrolyte and adopting a 2325 diaphragm, and standing the assembled battery for 12 hours for testing.
CN202010837410.7A 2020-08-19 2020-08-19 Method for improving stability of lithium battery silicon negative electrode material Active CN112028078B (en)

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CN1913200B (en) * 2006-08-22 2010-05-26 深圳市贝特瑞电子材料有限公司 Silicon carbone compound negative polar material of lithium ion battery and its preparation method
CN108448058B (en) * 2018-01-31 2021-12-17 华南理工大学 Surface modification method for lithium metal battery lithium cathode and lithium metal battery
CN109802109B (en) * 2018-12-29 2023-06-23 利信(江苏)能源科技有限责任公司 Method for pre-lithiating silicon-based negative electrode of battery and simultaneously forming SEI film

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