CN117638006B - Lithium metal fluoride high-entropy SEI layer, preparation method and application thereof - Google Patents
Lithium metal fluoride high-entropy SEI layer, preparation method and application thereof Download PDFInfo
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 93
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 title claims abstract description 88
- 238000002360 preparation method Methods 0.000 title claims abstract description 27
- 239000000843 powder Substances 0.000 claims abstract description 79
- 229910052751 metal Inorganic materials 0.000 claims abstract description 32
- 239000007788 liquid Substances 0.000 claims abstract description 31
- 239000002243 precursor Substances 0.000 claims abstract description 28
- 239000002184 metal Substances 0.000 claims abstract description 22
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 14
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 10
- 239000002253 acid Substances 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims description 40
- 239000000243 solution Substances 0.000 claims description 24
- 239000002904 solvent Substances 0.000 claims description 18
- 238000010304 firing Methods 0.000 claims description 16
- 230000008569 process Effects 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 12
- 239000006185 dispersion Substances 0.000 claims description 12
- 239000011812 mixed powder Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 11
- 238000005096 rolling process Methods 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 239000006104 solid solution Substances 0.000 claims description 7
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 6
- 238000000227 grinding Methods 0.000 claims description 6
- 239000000758 substrate Substances 0.000 claims description 6
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 6
- 150000001768 cations Chemical class 0.000 claims description 5
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 150000002148 esters Chemical class 0.000 claims description 4
- 239000003960 organic solvent Substances 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 239000012300 argon atmosphere Substances 0.000 claims description 3
- 239000011888 foil Substances 0.000 claims description 3
- 229920006254 polymer film Polymers 0.000 claims description 3
- 239000010410 layer Substances 0.000 abstract description 80
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 12
- 210000001787 dendrite Anatomy 0.000 abstract description 7
- 229910045601 alloy Inorganic materials 0.000 abstract description 6
- 239000000956 alloy Substances 0.000 abstract description 6
- 229940104869 fluorosilicate Drugs 0.000 abstract description 5
- 238000009413 insulation Methods 0.000 abstract description 5
- 230000008021 deposition Effects 0.000 abstract description 4
- 239000011241 protective layer Substances 0.000 abstract description 2
- 229910052573 porcelain Inorganic materials 0.000 description 27
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 18
- 239000003792 electrolyte Substances 0.000 description 17
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 12
- 239000000047 product Substances 0.000 description 12
- 239000002244 precipitate Substances 0.000 description 11
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 10
- 238000009826 distribution Methods 0.000 description 10
- 238000000605 extraction Methods 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 238000005303 weighing Methods 0.000 description 10
- 102000020897 Formins Human genes 0.000 description 9
- 108091022623 Formins Proteins 0.000 description 9
- 239000012298 atmosphere Substances 0.000 description 9
- 238000000354 decomposition reaction Methods 0.000 description 9
- 239000008367 deionised water Substances 0.000 description 9
- 229910021641 deionized water Inorganic materials 0.000 description 9
- 230000000630 rising effect Effects 0.000 description 9
- 239000013049 sediment Substances 0.000 description 9
- 239000003517 fume Substances 0.000 description 8
- -1 oxides Chemical class 0.000 description 8
- 210000004027 cell Anatomy 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000009210 therapy by ultrasound Methods 0.000 description 7
- 238000001291 vacuum drying Methods 0.000 description 7
- 238000004146 energy storage Methods 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 5
- XTHFKEDIFFGKHM-UHFFFAOYSA-N Dimethoxyethane Chemical compound COCCOC XTHFKEDIFFGKHM-UHFFFAOYSA-N 0.000 description 4
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 238000007086 side reaction Methods 0.000 description 4
- 229910013872 LiPF Inorganic materials 0.000 description 3
- 229910013870 LiPF 6 Inorganic materials 0.000 description 3
- 101150058243 Lipf gene Proteins 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- 230000005012 migration Effects 0.000 description 3
- 238000013508 migration Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 2
- 229910015475 FeF 2 Inorganic materials 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- IIPYXGDZVMZOAP-UHFFFAOYSA-N lithium nitrate Chemical compound [Li+].[O-][N+]([O-])=O IIPYXGDZVMZOAP-UHFFFAOYSA-N 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000007784 solid electrolyte Substances 0.000 description 2
- 238000000527 sonication Methods 0.000 description 2
- WXNUAYPPBQAQLR-UHFFFAOYSA-N B([O-])(F)F.[Li+] Chemical compound B([O-])(F)F.[Li+] WXNUAYPPBQAQLR-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910013075 LiBF Inorganic materials 0.000 description 1
- 229910013553 LiNO Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000010485 coping Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000002001 electrolyte material Substances 0.000 description 1
- 239000003759 ester based solvent Substances 0.000 description 1
- 239000004210 ether based solvent Substances 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910001512 metal fluoride Inorganic materials 0.000 description 1
- 229910003455 mixed metal oxide Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000011232 storage material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/02—Coating starting from inorganic powder by application of pressure only
- C23C24/06—Compressing powdered coating material, e.g. by milling
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/043—Processes of manufacture in general involving compressing or compaction
- H01M4/0435—Rolling or calendering
-
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
- H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/027—Negative electrodes
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
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- Engineering & Computer Science (AREA)
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- General Chemical & Material Sciences (AREA)
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- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention discloses a lithium metal fluorinated high-entropy SEI layer, a preparation method and application thereof in the technical field of lithium batteries, wherein a fluorosilicate precursor liquid is obtained by mixing a plurality of metal oxides or a plurality of metal powders with fluosilicic acid, the precursor liquid is thermally decomposed at 400-600 ℃ to prepare high-entropy fluoride powder, the high-entropy fluoride powder is rolled onto the surface of lithium metal, a fluorinated high-entropy SEI layer which is uniform, compact and stable in structure and has high mechanical strength and contains LiF and alloy is generated on the surface of lithium metal, the protective layer has electronic insulation and ionic conductivity, lithium uniform and compact deposition can be promoted, dendrite and electrode volume expansion are restrained, and the preparation process of the high-entropy SEI layer is simple and low in cost and can realize large-scale preparation.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a lithium metal fluoride high-entropy SEI layer.
Background
With the rapid development of portable electronic equipment and new energy automobiles, the requirements of people on the energy density of the secondary energy storage device are increasing. At present, the lithium ion battery energy storage system is widely used because of higher safety and higher output voltage, but the energy density of the lithium ion battery energy storage system is limited to be further improved due to an inherent intercalation and deintercalation mechanism of a graphite cathode. The lithium metal cathode has the lowest reduction potential (-3.04V vs standard hydrogen electrode) and the highest theoretical specific capacity (3860 mAh g -1 ) But is focused on, is a research hot spot in the current energy storage field, and is expected to become an ideal energy storage material of the next generation. In recent years, researchers have conducted intensive research on performance improvement of lithium metal batteries in order to further satisfy demands of people for high-energy-density energy storage devices.
However, lithium metal has extremely high chemical reactivity, is unstable in an electrolyte solution, and is extremely susceptible to side reactions with the electrolyte solution, thereby forming a solid electrolyte interface layer, i.e., an SEI layer, on the surface thereof, which may cause a reduction in coulombic efficiency and capacity fade of the battery to some extent. In addition, the lithium metal has the problems of volume expansion, dendrite growth and the like when being deposited and dissolved, so that the SEI layer on the surface of the lithium metal is continuously broken, fresh lithium is repeatedly exposed, and the lithium metal continuously reacts with the electrolyte to generate a new SEI layer, thereby causing the loss of active lithium and the electrolyte. And dead lithium wrapped by an electronic insulation SEI layer can be generated in the cycling process, so that the battery capacity is further reduced, and the development of a lithium metal battery is seriously restricted. In order to solve the problems, researchers have made a great deal of research to improve the electrochemical performance of the electrolyte, and propose methods for improving the formula of the electrolyte, preparing solid electrolyte, constructing a composite anode material and the like. However, the problem of the lithium metal battery is not completely solved at present, and further extensive research and study is still required.
In recent years, high-entropy materials (HEMs) have been greatly interested in having high entropy effect, lattice distortion, slow diffusion and "cocktail" effect, and are capable of maintaining stability of their structures, providing higher ion conductivity during continuous charge and discharge processes, and coping with challenges of lithium metal volume change, thanks to the four core advantages. Based on the concept of high entropy, researchers have successfully prepared HEMs such as fluorides, carbides, oxides, nitrides and the like, and have been widely applied to positive electrode, electrolyte and negative electrode materials. However, no methods have been reported to apply HEMs to the SEI layer to improve the ionic conductivity and electrochemical stability.
In addition, liF, which is one of the SEI components, has electron insulation properties, so that electrons can be effectively prevented from transiting to the surface of the SEI layer to react with the electrolyte, and deposition of lithium metal below the SEI layer is ensured, thereby inhibiting dendrite growth and volume expansion. And when LiF exists in the SEI layer, the SEI layer surface Li is greatly improved + Diffusion and migration rates of (c). However, the single inorganic component LiF protective layer has poor flexibility and complex preparation method, but cannot inhibit the large volume change of lithium metal, is easy to crack, and loses the protection effect on active lithium metal.
The invention prepares the high-entropy fluoride material by a thermal decomposition method and applies the material to be a lithium metal SEI layer. On one hand, the prepared high-entropy fluoride has good structural stability, ion conductivity and higher mechanical strength, can well protect a lithium metal layer, prevents side reactions between active lithium and electrolyte, and inhibits dendrite formation and volume expansion; on the other hand, the high-entropy fluoride reacts with lithium metal to generate uniform LiF and alloy layers on the surface of the lithium metal, the LiF improves the electronic insulation of the SEI layer, ensures that the lithium metal is deposited below the SEI layer, and improves the surface Li of the SEI layer + And the alloy layer further improves the ionic conductivity of the SEI layer. The prepared lithium metal fluorinated high-entropy SEI layer has important effects on inhibiting dendrite growth and volume expansion, improving ionic conductivity and structural stability of SEI layer, and can be improved to a great extentElectrochemical properties of lithium metal batteries.
Disclosure of Invention
Aiming at the problems of SEI layer cracking, dendrite growth, volume expansion and dead lithium existing in the cycling process of lithium metal with higher activity, the invention prepares the high-entropy fluoride with high stability by a thermal decomposition method and applies the fluoride to the SEI layer of the lithium metal cathode. After the high-entropy fluoride reacts with lithium metal, a uniform alloy layer and a LiF layer are formed, and the high-entropy fluoride has good ion conductivity, electronic insulativity and structural stability. The SEI layer provides uniform and rapid Li for lithium metal + Diffusion and migration of the surface promote uniform and compact deposition of lithium metal, and inhibit side reactions of lithium metal and electrolyte, thereby consuming active lithium and electrolyte.
The purpose of the invention is realized in the following way: a lithium metal fluoride high-entropy SEI layer has a plurality of metal elements which can be subjected to solid solution alloying with lithium metal.
A method for preparing a lithium metal fluoride high-entropy SEI layer, which is produced by thermal decomposition of metal oxides or metal powders containing a plurality of different metal elements and fluosilicic acid, comprising the steps of:
step 1), uniformly mixing metal oxides or metal powder containing more than five different metal elements through grinding to obtain mixed powder;
step 2) dissolving the mixed powder obtained in the step 1) in a set amount of acid solution to obtain a precursor solution;
step 3) placing the precursor liquid obtained in the step 2) in a tube furnace for firing, performing thermal decomposition reaction, volatilizing water in the precursor liquid, and decomposing fluorosilicate into SiF 4 Gas and corresponding fluoride. Back extraction, cooling and drying to obtain high-entropy fluoride powder;
step 4) uniformly dispersing the high-entropy fluoride powder obtained in the step 3) in a solvent, pouring the dispersion liquid on a substrate, and drying the solvent to obtain a uniformly spread high-entropy fluoride powder layer;
and 5) rolling the high-entropy fluoride powder layer obtained in the step 4) onto the surface of lithium metal, and reacting to obtain the lithium metal fluorinated high-entropy SEI layer.
As a further limitation of the preparation according to the invention, the metal oxide in step 1) is ZnO, mgO, cuO, niO, coO, mnO, snO, al 2 O 3 、In 2 O 3 、Sb 2 O 3 、Ag 2 O, etc.; the metal powder in the step 1) is aluminum powder, zinc powder, iron powder, tin powder, magnesium powder and nickel powder, and the metal powder, the zinc powder, the iron powder, the tin powder, the magnesium powder and the nickel powder are mixed according to the equimolar ratio of metal cations.
As a further limitation of the preparation according to the invention, the acid solution in step 2) is fluosilicic acid.
As a further limitation of the preparation method of the invention, the firing temperature of the tube furnace in the step 3) is set according to the selected raw materials, a single-phase solid solution product can be obtained at the set temperature, and the tube furnace is fired in an argon atmosphere for more than 2 h.
As a further limitation of the preparation method of the invention, the firing temperature of the tube furnace is set to be 400-600 ℃.
As a further limitation of the preparation according to the invention, the solvent in step 4) is an organic solvent of the esters or ethers type.
As a further definition of the preparation according to the invention, the substrate in step 4) is a metal foil or a polymer film material.
The application of the lithium metal fluoride high-entropy SEI layer comprises application in a lithium metal battery, and is particularly applied to a lithium metal anode.
Compared with the prior art, the invention has the beneficial effects that:
(1) The high entropy fluoride prepared by the invention is a single-phase solid solution with a rutile structure, and is not a simple mixture of several metal fluorides. The particle size of the material is nano-scale, is typical nano-particles, has good uniformity, and each nano-particle is uniformly distributed with a plurality of metal elements and F elements, so that the agglomeration or segregation phenomenon is avoided. The obtained high-entropy material has four core advantages of high entropy effect, lattice distortion, slow diffusion and 'cocktail' effect. The prepared high-entropy fluoride has good structural stability, ion conductivity and high mechanical strength.
(2) The prepared high-entropy fluoride is rolled on the surface of lithium metal to form an SEI layer. The high-entropy fluoride reacts with lithium metal to form a LiF layer and a high-entropy alloy layer on the surface of the lithium metal. LiF can promote SEI layer surface Li + And, because of its electron insulation, ensures that lithium metal is deposited below the SEI layer. The formed alloy layer further improves the ionic conductivity of the SEI layer and promotes Li + And transmitted to the lithium metal surface through the SEI layer.
(3) The high-entropy fluoride prepared by the method plays an important role in inhibiting the generation and growth of lithium metal dendrites, promoting uniform and compact deposition of lithium metal, relieving volume expansion generated in the cyclic process, improving the mechanical strength, structural stability, ionic conductivity and the like of an SEI layer, and greatly improving the electrochemical cyclic stability of a lithium metal negative electrode.
(4) The preparation method is low in cost aiming at the preparation raw materials of the lithium metal fluoride high-entropy SEI layer, is simple, and can realize large-scale production. Which provides uniform and rapid Li for lithium metal as an SEI layer + Diffusion and migration of the surface, inhibition of side reaction of lithium metal and electrolyte, consumption of active lithium and electrolyte, and improvement of battery capacity.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1 is a TEM image of the high entropy fluoride material prepared in example 1.
Fig. 2 is an XRD pattern of the high entropy fluoride material prepared in example 1, where C represents Cu and HEF refers to high entropy fluoride.
FIG. 3 is a graph of example 1, a symmetrical cell of comparative example 1 at 1 mA cm -2 -1 mAh cm -2 Under the condition, a comparison graph of cycle voltage-time curve shows that the concentration of electrolyte is 1 mol/L of lithium hexafluorophosphate (LiPF 6 ) Dissolved in a volume ratio of 1:1 of Ethylene Carbonate (EC) to diethyl carbonate (DEC). The membrane is a Celgard 2400 membrane.
FIG. 4 is a graph showing that the symmetric cell of example 2 was at 1 mA cm -2 -1 mAh cm -2 Under the condition, a comparison graph of cycle voltage-time curve shows that the concentration of electrolyte is 1 mol/L of lithium hexafluorophosphate (LiPF 6 ) Dissolved in a volume ratio of 1:1 of Ethylene Carbonate (EC) to diethyl carbonate (DEC).
FIG. 5 is a graph of the symmetric cell of example 3 at 1 mA cm -2 -1 mAh cm -2 Under the condition, a comparison graph of cycle voltage-time curve shows that the concentration of electrolyte is 1 mol/L of lithium hexafluorophosphate (LiPF 6 ) Dissolved in a volume ratio of 1:1 of Ethylene Carbonate (EC) to diethyl carbonate (DEC).
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention designs a high-entropy fluoride which is a single-phase solid solution and has good stability.
The invention relates to a preparation method of the high-entropy fluoride, which is obtained by thermal decomposition reaction of metal oxide or metal powder containing multiple elements and fluosilicic acid.
The metal oxide is as follows: znO, mgO, cuO, niO, coO, mnO, snO, al 2 O 3 、In 2 O 3 、Sb 2 O 3 、Ag 2 O, etc., the metal powder is: aluminum powder, zinc powder, iron powder, tin powder, magnesium powder, nickel powder and the like, and the selection type can be determined according to the situation during preparation.
The invention designs a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps:
step 1) mixing metal oxides or metal powders containing more than five different metal elements according to the equimolar ratio of cations, and grinding to uniformly mix the metal oxides or metal powders.
The metal oxide may be ZnO, mgO, cuO, niO, coO, mnO, snO, in 2 O 3 、Sb 2 O 3 、Ag 2 O, etc., wherein the metal powder can be selected from aluminum powder, zinc powder, iron powder, tin powder, magnesium powder, nickel powder, etc.; the preparation of the high-entropy fluoride needs to contain metal oxides or metal powders of more than five different metal elements, while the preparation of the low-entropy fluoride or mid-entropy fluoride can select the metal oxides or the metal powders containing less than five different metal elements; mixing is carried out according to the equimolar ratio of cations, and the molar ratio can be adjusted according to the requirement.
Step 2) dissolving the mixed powder prepared in the step 1) in a certain amount of H 2 SiF 6 Wherein the fluorosilicate ZnSiF is obtained after full reaction 6 、MgSiF 6 、CuSiF 6 、NiSiF 6 、CoSiF 6 、MnSiF 6 、SnSiF 6 、Al 2 (SiF 6 ) 3 、In 2 (SiF 6 ) 3 、Sb 2 (SiF 6 ) 3 、Ag 2 SiF 6 And FeSiF 6 And (3) fluorosilicate precursor solutions of different metal cations.
Said H 2 SiF 6 Anionic SiF of solution 6 2- The molar amount is greater than the total molar amount of mixed metal oxide obtained in step 1) to ensure adequate reaction to give the corresponding fluorosilicate.
And 3) measuring a certain amount of the precursor liquid obtained in the step 2), placing the precursor liquid in a tube furnace for firing, and then extracting and cooling in liquid nitrogen to obtain a precipitate.
The reaction is carried out, the set temperature of the tube furnace is 400-600 ℃, the temperature is adjusted according to the selected raw materials, a single-phase solid solution product can be obtained at a proper temperature, and the product is fired in an argon atmosphere for more than 2 h.
And 4) collecting the precipitate obtained in the step 3), and drying in vacuum at 80 ℃ to obtain the dried high-entropy fluoride powder.
Step 5) weighing a certain amount of the high-entropy fluoride powder prepared in the step 4), uniformly dispersing the high-entropy fluoride powder in a proper amount of solvent by an ultrasonic method, pouring the dispersion liquid on a substrate, and drying the solvent at 60 ℃ to obtain a uniformly spread high-entropy fluoride powder layer.
The solvent is an ester or ether organic solvent; the substrate is a metal foil or a polymer film material.
And 6) rolling the high-entropy fluoride powder layer obtained in the step 5) onto the surface of lithium metal, and the high-entropy fluoride powder layer can be used as a lithium battery.
The invention relates to an application of a lithium metal anode with a lithium metal fluorinated high-entropy SEI layer, which is used as an anode material to be matched with a diaphragm and electrolyte, so as to assemble a lithium metal symmetrical battery.
The electrolyte comprises: 1 mol/L lithium bistrifluoromethane sulfonyl imide (LiTFSI) dissolved in organic solvent 1, 3-Dioxypentacyclic (DOL) or ethylene glycol dimethyl ether (DME) and 2% lithium nitrate (LiNO) is added 3 ) The method comprises the steps of carrying out a first treatment on the surface of the Lithium hexafluorophosphate (LiPF) at a concentration of 0.2 mol/L 6 ) 0.2 mol/L lithium tetrafluoroborate (LiBF) 4 ) 0.8 mol/L lithium difluoroborate (LiDFOB) dissolved in diethyl carbonate (DEC) and fluoroethylene carbonate (FEC) in a volume ratio of 2:1; lithium bistrifluoromethane sulfonyl imide (LiTFSI) at a concentration of 1 mol/L was dissolved in 1:1 by volume of ethylene glycol dimethyl ether (DME) and 1, 3-Dioxapentacyclic (DOL); lithium hexafluorophosphate (LiPF) at a concentration of 1 mol/L 6 ) One or more lithium salts such as Ethylene Carbonate (EC) and diethyl carbonate (DEC) dissolved in a volume ratio of 1:1 are dissolved in one of the electrolytes of the ester or ether solvents. The electrolyte used in the battery assembly of this example was lithium hexafluorophosphate (LiPF) having a concentration of 1 mol/L 6 ) Dissolved in a volume ratio of 1:1 of Ethylene Carbonate (EC) to diethyl carbonate (DEC).
The diaphragm includes: common lithium battery separators such as Celgard 2400 separator, celgard 2500 separator, celgard 2325 separator, etc. The separator used in this example in assembling the symmetrical cell was a Celgard 2400 separator.
The invention will be further illustrated with reference to specific examples.
Example 1.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) mixing and grinding 187 and mg of the reducing Fe powder, 250 and mg of CoO, 250 and mg of NiO, 267 and mg of CuO and 272 and mg of ZnO, and uniformly mixing.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain FeSiF 6 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 400 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 4) collecting the precipitate obtained in the step 3), and vacuum drying at 80 ℃ to obtain dried high-entropy fluoride powder (FeCoNiCuZn) F 2 。
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer with TEM and XRD pattern distributions as shown in figures 1, 2.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 2.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) mixing and grinding 187 and mg of the reducing Fe powder, 250 and mg of CoO, 250 and mg of NiO, 134 and mg of MgO and 272 and mg of ZnO, and uniformly mixing.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain FeSiF 6 、CoSiF 6 、NiSiF 6 、MgSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 4) collecting the precipitate obtained in the step 3), and vacuum drying at 80 ℃ to obtain dried high-entropy fluoride powder (FeCoNiMgZn) F 2 。
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 3.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) mixing 247 mg MnO, 250 mg CoO, 250 mg NiO, 267 mg CuO and 272 mg ZnO, and grinding to uniformly mix the materials.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain MnSiF 6 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 4) collecting the precipitate obtained in the step 3), and vacuum drying at 80 ℃ to obtain dried high-entropy fluoride powder (MnCoNiCuZn) F 2 。
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 4.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) SnO of 468 mg, coO of 250 mg, niO of 250 mg, cuO of 267 mg, znO of 272 mg are mixed and ground to be uniformly mixed.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain SnSiF 6 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 4) collecting the precipitate obtained in the step 3), and vacuum drying at 80 ℃ to obtain dried high-entropy fluoride powder (SnCoNiCuZn) F 2 。
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 5.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) Ag of 403 mg 2 O, coO of 250 mg, niO of 250 mg, cuO of 267 mg and ZnO of 272 mg are mixed and ground to be uniformly mixed.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain Ag 2 SiF 6 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 4) collecting the precipitate obtained in the step 3), and vacuum drying at 80deg.C to obtain dried high entropy fluoride powder (Ag) 2 CoNiCuZn)F 2 。
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 6.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) In of 483 mg 2 O 3 The CoO of 250 mg, niO of 250 mg, cuO of 267 mg, znO of 272 mg were mixed and ground to be uniformly mixed.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h In a fume hood to obtain In 3 (SiF 6 ) 2 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
And 4) collecting the precipitate obtained in the step 3), and drying in vacuum at 80 ℃ to obtain the dried high-entropy fluoride powder.
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Example 7.
The invention provides a preparation method of a lithium metal fluoride high-entropy SEI layer, which specifically comprises the following steps.
Step 1) Sb of 507 mg 2 O 3 The CoO of 250 mg, niO of 250 mg, cuO of 267 mg, znO of 272 mg were mixed and ground to be uniformly mixed.
Step 2) dissolving the mixed powder prepared in the step 1) in 10 g of H 2 SiF 6 Adding 12 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain Sb 2 (SiF 6 ) 3 、CoSiF 6 、NiSiF 6 、CuSiF 6 And ZnSiF 6 Equimolar mixed precursor solution.
And 3) measuring 2 mL, placing the precursor liquid obtained in the step 2) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 600 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
And 4) collecting the precipitate obtained in the step 3), and drying in vacuum at 80 ℃ to obtain the dried high-entropy fluoride powder.
Step 5) weighing 50 mg of the high-entropy fluoride powder prepared in step 4), uniformly dispersing the powder in 10 mL of ethanol by ultrasonic treatment for 10 min, and then pouring the dispersion on 8×8 cm release paper. The solvent was then dried at 60 ℃ to give a uniformly spread high entropy fluoride powder layer.
Step 6) rolling the high-entropy fluoride powder layer obtained in the step 5) to the surface of lithium metal, wherein the distribution content of the obtained high-entropy fluoride is 0.78 mg cm -2 。
Comparative example 1.
The comparative example 1 provides a method for preparing a fluorinated SEI layer, specifically comprising the following steps.
Step 1) dissolving 187 mg of the reduced Fe powder in 2 g H 2 SiF 6 Adding 3 g deionized water into the solution (30 wt%), and fully reacting 24 h in a fume hood to obtain FeSiF 6 Precursor liquid.
And 2) measuring 2 mL, placing the precursor liquid obtained in the step 1) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 400 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 3) collecting the precipitate obtained in the step 2), and vacuum drying at 80 ℃ to obtain dried FeF 2 And (3) powder.
Step 4) weighing 50 percent mg percent of FeF prepared in the step 3) 2 The powder was uniformly dispersed in 10 mL ethanol by sonication for 10 min, and the dispersion was then poured onto 8×8 cm release paper. Drying the solvent at 60 ℃ to obtain FeF which is uniformly spread 2 A powder layer.
Step 5) FeF obtained in step 4) 2 Powder layer rolling to lithium metal surface to obtain FeF 2 The distribution content of the powder was 0.78 mg cm -2 。
Comparative example 2.
The comparative example 2 provides a method for preparing a fluorinated SEI layer, specifically comprising the following steps.
Step 1) dissolving 272 mg ZnO in 2 g H 2 SiF 6 To the solution (30 wt%) was added 3 g deionized water continuously, followed by passageFully reacting 24 h in a wind cabinet to obtain ZnSiF 6 Precursor liquid.
And 2) measuring 2 mL, placing the precursor liquid obtained in the step 1) in a porcelain boat, and then placing the porcelain boat in a tube furnace for firing. The temperature rising rate is set to 5 ℃ for min -1 Raising the temperature to 400 ℃ and maintaining the temperature to 3 h, wherein the whole process is carried out in an argon-introducing atmosphere; after the decomposition procedure is finished, the porcelain boat carrying the product is placed in liquid nitrogen for extraction and cooling, and sediment is obtained.
Step 3) collecting the precipitate obtained in the step 2), and vacuum drying at 80 ℃ to obtain dried ZnF 2 And (3) powder.
Step 4) weighing 50 percent mg percent of ZnF prepared in the step 3) 2 The powder was uniformly dispersed in 10 mL ethanol by sonication for 10 min, and the dispersion was then poured onto 8×8 cm release paper. Drying the solvent at 60 ℃ to obtain uniformly spread ZnF 2 A powder layer.
Step 5) ZnF obtained in step 4) 2 Powder layer is rolled to the surface of lithium metal, and ZnF is obtained 2 The distribution content of (C) is 0.78 mg cm -2 。
The following is a description of the comparison of example 1, example 2, example 3 and comparative example 1.
As shown in FIG. 3, the temperature was 1 mAcm -2 -1 mAh cm -2 The overpotential of the symmetrical cell of comparative example 1 increased to approximately 100 mV over time and a short circuit occurred after 400 h. In contrast, the lithium metal symmetric battery with the lithium metal fluorinated high entropy SEI layer prepared in example 1 has more stable electrochemical performance, with over-potential stabilization cycles as low as 50 mV of 500 to h. As shown in fig. 4 and 5, the symmetrical cell corresponding to example 2 was stabilized at an overpotential as low as 30 mV for 500 or more, and the symmetrical cell corresponding to example 3 was likewise stabilized at an overpotential as low as 50 mV for 500 or more.
The above description of the embodiments is only for aiding in the understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (8)
1. A method for preparing a lithium metal fluoride high-entropy SEI layer, characterized by being produced from five or more metal oxides and/or metal powders containing different metal elements and fluosilicic acid by thermal decomposition, comprising the steps of:
step 1), grinding and uniformly mixing more than five metal oxides and/or metal powders containing different metal elements to obtain mixed powder;
step 2), dissolving the mixed powder obtained in the step 1) in a quantitative fluosilicic acid solution to obtain a precursor solution;
step 3) placing the precursor liquid obtained in the step 2) in a tube furnace for firing, and then extracting, cooling and drying to obtain high-entropy fluoride powder;
step 4) uniformly dispersing the high-entropy fluoride powder obtained in the step 3) in a solvent, pouring the dispersion liquid on a substrate, and drying the solvent to obtain a uniformly spread high-entropy fluoride powder layer;
and 5) rolling the high-entropy fluoride powder layer obtained in the step 4) onto the surface of lithium metal, and reacting to obtain the lithium metal fluorinated high-entropy SEI layer.
2. The process according to claim 1, wherein the metal oxide in step 1) is ZnO, mgO, cuO, niO, coO, mnO, snO, al 2 O 3 、In 2 O 3 、Sb 2 O 3 、Ag 2 One or more of O; the metal powder in the step 1) is one or more of aluminum powder, zinc powder, iron powder, tin powder, magnesium powder and nickel powder, and the metal powder, the zinc powder, the iron powder, the tin powder, the magnesium powder and the nickel powder are mixed according to the equimolar ratio of metal cations.
3. The method according to claim 2, wherein the firing temperature setting of the tube furnace in step 3) is adjusted according to the selected raw materials, a single-phase solid solution product is obtained at the setting temperature, and the tube furnace is fired in an argon atmosphere of 2 or more h.
4. A method according to claim 3, wherein the firing temperature of the tube furnace is set at 400-600 ℃.
5. The method according to claim 2, wherein the solvent in step 4) is an ester or ether organic solvent.
6. The method of claim 2, wherein the substrate in step 4) is a metal foil or a polymer film material.
7. A lithium metal fluorinated high-entropy SEI layer, characterized in that it is produced by the method according to any one of claims 1 to 6, and has a plurality of metal elements that can be solid-solution alloyed with lithium metal.
8. Use of the lithium metal fluorinated high-entropy SEI layer prepared by the preparation method according to any one of claims 1 to 6, in a lithium metal battery, in particular for a lithium metal negative electrode.
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