CN117059771A - Lithiated fluorine-containing polymer coated positive electrode material, preparation method and application thereof - Google Patents
Lithiated fluorine-containing polymer coated positive electrode material, preparation method and application thereof Download PDFInfo
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- CN117059771A CN117059771A CN202311072483.1A CN202311072483A CN117059771A CN 117059771 A CN117059771 A CN 117059771A CN 202311072483 A CN202311072483 A CN 202311072483A CN 117059771 A CN117059771 A CN 117059771A
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- positive electrode
- electrode material
- lithiated
- fluorine
- lithium
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 59
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 239000011737 fluorine Substances 0.000 title claims abstract description 41
- 229910052731 fluorine Inorganic materials 0.000 title claims abstract description 41
- 229920000642 polymer Polymers 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 45
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 42
- 238000001354 calcination Methods 0.000 claims abstract description 29
- 229920002313 fluoropolymer Polymers 0.000 claims abstract description 25
- 239000004811 fluoropolymer Substances 0.000 claims abstract description 25
- 239000002904 solvent Substances 0.000 claims abstract description 24
- 239000004094 surface-active agent Substances 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 15
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 239000002243 precursor Substances 0.000 claims abstract description 9
- 229910052751 metal Inorganic materials 0.000 claims abstract description 7
- 239000002184 metal Substances 0.000 claims abstract description 7
- 238000001035 drying Methods 0.000 claims abstract description 5
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 18
- -1 polytetrafluoroethylene, perfluoroethylene propylene Polymers 0.000 claims description 13
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 claims description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 10
- 229910001416 lithium ion Inorganic materials 0.000 claims description 10
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 8
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 claims description 8
- BGTOWKSIORTVQH-UHFFFAOYSA-N cyclopentanone Chemical compound O=C1CCCC1 BGTOWKSIORTVQH-UHFFFAOYSA-N 0.000 claims description 8
- UUEWCQRISZBELL-UHFFFAOYSA-N 3-trimethoxysilylpropane-1-thiol Chemical compound CO[Si](OC)(OC)CCCS UUEWCQRISZBELL-UHFFFAOYSA-N 0.000 claims description 6
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 claims description 6
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 5
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- FLKPEMZONWLCSK-UHFFFAOYSA-N diethyl phthalate Chemical compound CCOC(=O)C1=CC=CC=C1C(=O)OCC FLKPEMZONWLCSK-UHFFFAOYSA-N 0.000 claims description 4
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 4
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 4
- PEVRKKOYEFPFMN-UHFFFAOYSA-N 1,1,2,3,3,3-hexafluoroprop-1-ene;1,1,2,2-tetrafluoroethene Chemical compound FC(F)=C(F)F.FC(F)=C(F)C(F)(F)F PEVRKKOYEFPFMN-UHFFFAOYSA-N 0.000 claims description 3
- SJECZPVISLOESU-UHFFFAOYSA-N 3-trimethoxysilylpropan-1-amine Chemical compound CO[Si](OC)(OC)CCCN SJECZPVISLOESU-UHFFFAOYSA-N 0.000 claims description 3
- 229920001780 ECTFE Polymers 0.000 claims description 3
- 229920000840 ethylene tetrafluoroethylene copolymer Polymers 0.000 claims description 3
- 229920002620 polyvinyl fluoride Polymers 0.000 claims description 3
- ALVYUZIFSCKIFP-UHFFFAOYSA-N triethoxy(2-methylpropyl)silane Chemical compound CCO[Si](CC(C)C)(OCC)OCC ALVYUZIFSCKIFP-UHFFFAOYSA-N 0.000 claims description 3
- AVQQQNCBBIEMEU-UHFFFAOYSA-N 1,1,3,3-tetramethylurea Chemical compound CN(C)C(=O)N(C)C AVQQQNCBBIEMEU-UHFFFAOYSA-N 0.000 claims description 2
- LVNLBBGBASVLLI-UHFFFAOYSA-N 3-triethoxysilylpropylurea Chemical compound CCO[Si](OCC)(OCC)CCCNC(N)=O LVNLBBGBASVLLI-UHFFFAOYSA-N 0.000 claims description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 2
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 2
- DOOTYTYQINUNNV-UHFFFAOYSA-N Triethyl citrate Chemical compound CCOC(=O)CC(O)(C(=O)OCC)CC(=O)OCC DOOTYTYQINUNNV-UHFFFAOYSA-N 0.000 claims description 2
- AMSAPKJTBARTTR-UHFFFAOYSA-N butan-2-yl(trimethoxy)silane Chemical compound CCC(C)[Si](OC)(OC)OC AMSAPKJTBARTTR-UHFFFAOYSA-N 0.000 claims description 2
- 229920001577 copolymer Polymers 0.000 claims description 2
- GNOIPBMMFNIUFM-UHFFFAOYSA-N hexamethylphosphoric triamide Chemical compound CN(C)P(=O)(N(C)C)N(C)C GNOIPBMMFNIUFM-UHFFFAOYSA-N 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229920000259 polyoxyethylene lauryl ether Polymers 0.000 claims description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 2
- 239000001069 triethyl citrate Substances 0.000 claims description 2
- VMYFZRTXGLUXMZ-UHFFFAOYSA-N triethyl citrate Natural products CCOC(=O)C(O)(C(=O)OCC)C(=O)OCC VMYFZRTXGLUXMZ-UHFFFAOYSA-N 0.000 claims description 2
- 235000013769 triethyl citrate Nutrition 0.000 claims description 2
- DQWPFSLDHJDLRL-UHFFFAOYSA-N triethyl phosphate Chemical compound CCOP(=O)(OCC)OCC DQWPFSLDHJDLRL-UHFFFAOYSA-N 0.000 claims description 2
- LDVVTQMJQSCDMK-UHFFFAOYSA-N 1,3-dihydroxypropan-2-yl formate Chemical compound OCC(CO)OC=O LDVVTQMJQSCDMK-UHFFFAOYSA-N 0.000 claims 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims 1
- 229910052748 manganese Inorganic materials 0.000 claims 1
- 239000011572 manganese Substances 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 claims 1
- BPSIOYPQMFLKFR-UHFFFAOYSA-N trimethoxy-[3-(oxiran-2-ylmethoxy)propyl]silane Chemical compound CO[Si](OC)(OC)CCCOCC1CO1 BPSIOYPQMFLKFR-UHFFFAOYSA-N 0.000 claims 1
- PQXKHYXIUOZZFA-UHFFFAOYSA-M lithium fluoride Chemical compound [Li+].[F-] PQXKHYXIUOZZFA-UHFFFAOYSA-M 0.000 abstract description 34
- 239000011247 coating layer Substances 0.000 abstract description 17
- 239000003792 electrolyte Substances 0.000 abstract description 7
- 238000007086 side reaction Methods 0.000 abstract description 7
- 230000001351 cycling effect Effects 0.000 abstract description 6
- 238000000576 coating method Methods 0.000 description 10
- 239000011248 coating agent Substances 0.000 description 9
- 238000006115 defluorination reaction Methods 0.000 description 7
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 7
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000010405 anode material Substances 0.000 description 5
- 239000010406 cathode material Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 230000014759 maintenance of location Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 230000001276 controlling effect Effects 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- VBICKXHEKHSIBG-UHFFFAOYSA-N 1-monostearoylglycerol Chemical compound CCCCCCCCCCCCCCCCCC(=O)OCC(O)CO VBICKXHEKHSIBG-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 101100136092 Drosophila melanogaster peng gene Proteins 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229940075507 glyceryl monostearate Drugs 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000001788 mono and diglycerides of fatty acids Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- HQYALQRYBUJWDH-UHFFFAOYSA-N trimethoxy(propyl)silane Chemical compound CCC[Si](OC)(OC)OC HQYALQRYBUJWDH-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- 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
- 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
- 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
-
- 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
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a preparation method of a lithiated fluoropolymer coated positive electrode material, which comprises the following steps: firstly, dissolving fluorine-containing polymer in a solvent I to obtain a solution A; adding metal lithium into the solution A according to a certain proportion, and mixing for a certain time to obtain a solution B containing lithiated fluorine-containing polymer; secondly, dispersing the positive electrode material in a solvent II, adding a surfactant, heating and reacting for a certain time, and centrifugally drying the product to obtain a pretreated positive electrode material; finally, adding the pretreated positive electrode material into the solution B, uniformly mixing, and removing the solvent to obtain a precursor; and calcining the precursor to obtain the lithiated fluorine-containing polymer coated positive electrode material. The surface of the positive electrode material prepared by the method is coated with the continuous and uniform lithium fluoride coating layer, so that the side reaction of the interface between the positive electrode material and the electrolyte under high voltage can be inhibited, the cycling stability of the positive electrode material under high voltage is improved, and the method has wide popularization and application prospects.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithiated fluorine-containing polymer coated positive electrode material and a preparation method thereof, and application of the lithiated fluorine-containing polymer coated positive electrode material in a lithium ion battery.
Background
From the current application market, lithium ion batteries are mainly applied to the fields of portable electronic equipment, electric automobiles, energy storage power stations and the like. Along with the continuous improvement of the requirements of electronic products on the energy density and the cycle life of the battery, higher requirements are also put on the performance of the anode and cathode materials of the battery. The specific capacities of the currently commercialized anode materials of lithium iron phosphate (LFP), lithium Cobalt Oxide (LCO) and ternary materials (NCM) are far lower than that of a graphite anode (more than 300mAh g) -1 ) Therefore, increasing the specific capacity of the positive electrode material is a key to further increasing the energy density of the lithium ion battery.
Increasing the cutoff voltage of the positive electrode material is an effective method of increasing its specific capacity, but brings new interface problems. The anode material can have serious side reaction with an electrolyte interface under high voltage, so that the dissolution of transition metal and the loss of lattice oxygen are caused, and the electrochemical performances of the anode material, such as cycle stability, rate discharge and the like, are drastically reduced. Coating lithium fluoride on the surface of the positive electrode material can effectively solve the problem of interfacial side reaction, and in the document Ceramics International (2022,48,10288), liF coating layers obtained by using the traditional coating method, such as Li, are too thick and uneven, can generate larger polarization and are unfavorable for long-period circulation. In order to obtain a thin and continuous coating, peng et al used magnetron sputtering to coat thin lithium fluoride on the surface of the positive electrode material in literature Nanomaterials (2021,11,3393), but this method is a costly process and is difficult to implement for large scale applications.
Based on the above, a preparation method capable of forming a continuous, uniform and ultrathin LiF coating layer is researched, and the preparation method has important significance for application and development of a positive electrode material in electric automobiles, portable electronic equipment and energy storage power stations, and is also a technical problem to be solved.
Disclosure of Invention
One of the objects of the present invention is to provide a method for preparing a positive electrode material having a continuous, uniform, ultra-thin lithium fluoride coating layer.
The second object of the present invention is to provide a lithiated fluoropolymer-coated positive electrode material having better cycling stability and electrochemical performance at high voltages.
The invention further aims to provide an application of the lithiated fluorine-containing polymer coated positive electrode material in a lithium ion battery.
One of the achievement purposes of the invention adopts the technical proposal that: the preparation method of the lithiated fluorine-containing polymer coated positive electrode material comprises the following steps:
s1, dissolving a fluorine-containing polymer in a solvent I to obtain a solution A; adding metal lithium into the solution A according to a certain proportion, and mixing for a certain time to obtain a solution B containing lithiated fluorine-containing polymer;
s2, dispersing the positive electrode material in a solvent II, adding a surfactant, heating and reacting for a certain time, and centrifugally drying the product to obtain a pretreated positive electrode material;
s3, adding the pretreated positive electrode material into the solution B, uniformly mixing, and removing the solvent to obtain a precursor; and calcining the precursor to obtain the lithiated fluorine-containing polymer coated positive electrode material.
The general idea of the lithiated fluoropolymer coated positive electrode material provided by the invention is as follows:
the invention adopts the fluorine-containing polymer and the lithium metal as raw materials to prepare the lithiated fluorine-containing polymer, and compared with other raw materials, the fluorine-containing polymer has the advantages of low cost, high air stability, high thermal stability and the like. Furthermore, the fluorine-containing polymer is subjected to defluorination reaction to form a hydrogen bond with the positive electrode material treated by the surfactant, the lithiated fluorine-containing polymer is tightly coated on the surface of the positive electrode material under the action of the hydrogen bond, and then the subsequent calcination treatment is carried out to finally form the ultrathin continuous uniform LiF coating layer. The compact and uniform LiF coating layer on the surface of the positive electrode material can inhibit side reactions of the interface between the positive electrode material and the electrolyte under high voltage, so that the cycling stability of the positive electrode material under high voltage is improved.
Further, in step S1, the fluorine-containing polymer includes one or more of Polytetrafluoroethylene (PTFE), perfluoroethylene propylene copolymer (FEP), polytrifluoroethylene (PCTFE), soluble Polytetrafluoroethylene (PFA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), hexafluoropropylene-vinylidene fluoride copolymer (THV), polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE).
In step S1, the concentration of the fluoropolymer in the solution A is 0.1-10 wt.%, and the molar ratio of the metal lithium to the fluoropolymer is (0.1-10): 1. In the present invention, the amount of lithium metal determines the extent of defluorination of the fluoropolymer, and excessive lithium may lead to the formation of by-products. The addition amount of the metal lithium is controlled within a proper range, so that defluorination is more thorough, and more lithium fluoride products are formed. Preferably, the molar ratio of lithium metal to fluoropolymer in solution A is (1-5): 1. In the present invention, by controlling the concentration of the fluoropolymer and the molar ratio of the metallic lithium to the fluoropolymer, uniform dispersion of the fluoropolymer is facilitated and contact with the cathode material is more uniform in the subsequent steps.
Further, the solution A contains a certain amount of water, which is more beneficial to defluorination of the fluorine-containing polymer; meanwhile, the moisture content is not easy to be too high, otherwise, the fluorine-containing polymer is swelled, and the generation of lithium fluoride is not facilitated. Preferably, step S1 further comprises: and (3) adjusting the water content of the solution A to ensure that the water content concentration of the solution A is 30-500 ppm.
Preferably, in step S1, the temperature of mixing is 35-45 ℃, and the mixing time is 6-12 hours. The proper elevated mixing temperature accelerates the defluorination reaction process of the fluorine-containing polymer, and the sufficient mixing time ensures that the defluorination reaction is finished.
Further, in step S1, the solvent I is selected from one or more of acetone, butanone, cyclohexanone, cyclopentanone, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, N-dimethylformamide, dimethylacetamide, hexamethylphosphoric triamide, diethyl carbonate, diethyl phthalate, propylene carbonate, triethyl citrate, triethyl phosphate, and tetramethylurea.
Further, in step S2, the solvent II is selected from one or more of benzene, toluene, acetone, butanone, cyclohexanone, cyclopentanone, tetrahydrofuran, and absolute ethanol.
Preferably, the solvent I is selected from acetone, butanone, N-methylpyrrolidone and N, N-dimethylformamide, and the solvent II is selected from toluene, acetone and absolute ethyl alcohol, which are more favorable for defluorination reaction.
Further, in step S2, the positive electrode material includes one of lithium cobaltate, lithium iron phosphate, ternary high nickel and lithium-rich manganese, and also includes other positive electrode materials of lithium ion batteries such as metal oxides.
Further, in step S2, the surfactant includes one or more of polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, isobutyl triethoxysilane, 3-butyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl trimethoxysilane, gamma-ureido propyl triethoxysilane, 3- (2, 3-glycidoxy) propyl trimethoxysilane, and glyceryl monostearate.
Preferably, the mass volume ratio of the pretreated positive electrode material to the surfactant is 1 (1-4) g/mL.
Preferably, in step S2, the temperature of the heating reaction is 80-90 ℃, and the time of the heating reaction is 4-8 hours. The heating reaction conditions described above help the surfactant to hydrolyze and form a bond with the surface of the positive electrode material.
Further, in step S3, the molar ratio of the pretreated positive electrode material to the lithiated fluoropolymer is 1 (0.001-0.2). By adjusting the proportion, the thickness of the coating layer is regulated and controlled. Preferably, the molar ratio of the pretreated cathode material to the lithiated fluoropolymer is 1 (0.001 to 0.01).
In step S3, the solvent may be removed by heating and volatilizing, and the temperature of heating and stirring used for volatilizing the solvent of the mixed system is 40-90 ℃.
Further, the temperature of the calcination treatment is 300-850 ℃, and the time of the calcination treatment is 3-15 h; preferably, the temperature of the calcination treatment is 400-750 ℃, and the time of the calcination treatment is 5-10 h; more preferably, the temperature of the calcination treatment is 550 to 600 ℃, and the time of the calcination treatment is 5 to 8 hours. In this step, the organic residue can be effectively removed by controlling the proper calcination temperature and calcination time, and a more uniform coating layer can be obtained.
In some preferred embodiments, the positive electrode material is lithium cobaltate, and the preparation method thereof comprises the following steps:
s1, dissolving fluorine-containing polymer in a solvent I to obtain a solution A, and regulating the water content in the solution A to be 50-300 ppm; according to the molar ratio of the metal lithium to the fluorine-containing polymer in the solution A being (1-5): 1, adding the metal lithium into the solution A, and mixing for 4-24 hours to obtain a solution B containing the lithiated fluorine-containing polymer;
s2, dispersing lithium cobaltate in a solvent II, and then adding a surfactant, wherein the mass volume ratio of the lithium cobaltate to the surfactant in the solvent II is 1: (1-5) g/mL, heating at 80-90 ℃ to react for 4-8 h, centrifuging and drying the product to obtain pretreated lithium cobaltate;
s3, adding the pretreated lithium cobaltate into the solution B according to the mol ratio of the pretreated lithium cobaltate to the lithiated fluorine-containing polymer of 1 (0.001-0.01), uniformly mixing, stirring and heating at 40-90 ℃ to remove the solvent to obtain a precursor; and calcining the precursor to obtain the lithium cobalt oxide coated by the lithiated fluorine-containing polymer.
In the preparation method, after the lithium cobaltate treated by the surfactant is soaked in the lithiated fluorine-containing polymer solution for a certain time, the continuous and uniform lithium fluoride-rich coating layer can be formed through solvent removal and calcination treatment. The coating layer inhibits side reaction of the interface between lithium cobalt oxide and electrolyte under high voltage, and improves the circulation stability of the lithium cobalt oxide under high voltage. Since the lithium fluoride coating layer is thin and uniform (the thickness is only 2-3 nm), the interface protection effect is achieved, and meanwhile, the rate performance of the battery is not negatively affected.
The second technical scheme adopted for realizing the purpose of the invention is as follows: there is provided a lithiated fluoropolymer-coated positive electrode material made by a preparation method according to one of the objects of the present invention.
The third technical scheme adopted for realizing the purpose of the invention is as follows: the invention provides an application of a lithiated fluorine-containing polymer coated positive electrode material prepared by the preparation method in a lithium ion battery.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the preparation method of the lithiated fluorine-containing polymer coated positive electrode material, provided by the invention, the lithiated fluorine-containing polymer is adopted to form a continuous, uniform and thin lithium fluoride coating layer on the surface of the positive electrode material, so that the side reaction of the electrolyte interface of the positive electrode material at a high voltage interface is inhibited, and the cycling stability of the positive electrode material is greatly improved. The fluorine-containing polymer and the solvent thereof used in the preparation method are all materials commonly used in industry, and have the advantages of low cost, simple process, strong controllability, strong expansibility and easy industrialization, and the reaction does not need special atmosphere protection.
(2) The lithium fluoride coating layer of the prepared lithiated fluorine-containing polymer coated positive electrode material has controllable thickness, and the coating layer has compact structure and uniform thickness due to the existence of hydrogen bond. The cathode material is applied to a lithium ion battery, can effectively improve the cycling stability under the high-voltage condition, and has the advantages that the thin and uniform lithium fluoride coating layer can not adversely affect the multiplying power performance of the battery while playing an interface protection effect, and has wide popularization and application prospects.
Drawings
FIG. 1 shows XPS results of high voltage lithium cobaltate prepared in example 1 of the present invention;
FIG. 2 is a TEM spectrum of high voltage lithium cobalt oxide obtained in example 1 of the present invention;
FIG. 3 is a graph showing capacity retention rate after the high voltage lithium cobaltate prepared in examples 1-3 of the present invention and the lithium cobaltate provided in comparative example 1 are cycled for 100 weeks at 0.5C rate at room temperature in a voltage range of 3-4.6V;
FIG. 4 is a graph showing the comparison of the rate performance of the lithium cobaltate prepared in example 2 of the present invention and the lithium cobaltate prepared in comparative example 1 at room temperature in the voltage range of 3-4.6V.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in connection with the embodiments, and it is obvious that the described embodiments are only some embodiments of the present invention, 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.
It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
The invention will be further illustrated, but is not limited, by the following examples.
The main raw materials and parameters related to each example of the present invention are shown in the following table 1;
TABLE 1
Example 1:
the preparation method of the lithiated fluorine-containing polymer coated high-voltage lithium cobaltate comprises the following steps:
step 1: dissolving PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer) in an acetone solution at a concentration of 0.25wt% to prepare a solution A, adding trace moisture into the solution A, and controlling the water content of the solution A to be 30-500ppm; 20mL of solution A was taken, 0.022g of metallic lithium was added thereto, and the reaction was heated and stirred at 40℃for 8 hours to obtain solution B.
Step 2: 10g of lithium cobaltate powder was dispersed in 90mL of absolute ethanol, 20mL of isobutyltriethoxysilane was added at the same time, and after heating and stirring at 85℃for 6 hours, the mixture was centrifuged and dried to obtain pretreated lithium cobaltate powder.
Step 3: and (3) adding 10g of the pretreated lithium cobaltate obtained in the step (2) into the solution B obtained in the step (1), stirring for 3 hours, and heating to 180 ℃ until the solvent is completely volatilized. And then carrying out calcination heat treatment on the obtained precursor in an air atmosphere, wherein the calcination temperature is 600 ℃, and the calcination time is 6 hours, so that the high-voltage lithium cobaltate material coated by the lithiated fluorine-containing polymer is obtained.
Example 2
In comparison with example 1, only the coating amount in step 1 was changed, and coating was performed by reacting 10mL of solution A with 0.0111 g of lithium, and the other conditions were unchanged.
Example 3
In comparison with example 1, only the coating amount in step 1 was changed, and the coating was performed by reacting 30mL of solution A and 0.033g of lithium, with the other conditions unchanged.
Example 4
Compared with example 1, only the fluoropolymer in step 1 was changed to perfluoroethylene propylene copolymer (FEP), the calcination temperature in step 3 was 550℃and the calcination time was 7 hours, and the other conditions were unchanged.
Example 5
Compared with example 1, only the fluoropolymer in the step 1 is changed to be fusible Polytetrafluoroethylene (PFA), the calcining temperature in the step 3 is 550 ℃, the calcining time is 6 hours, and the rest conditions are unchanged.
Example 6
The surfactant in step 2 was changed to 3-mercaptopropyl trimethoxysilane only as compared to example 4, with the remaining conditions unchanged.
Example 7
The surfactant in step 2 was changed to 3-aminopropyl trimethoxysilane only as compared to example 4, with the remaining conditions unchanged.
Example 8
Compared with the embodiment 1, only the positive electrode material in the step 2 is changed to be lithium iron phosphate, the surfactant is 3-mercaptopropyl trimethoxy silane, the mass volume ratio of the surfactant of the positive electrode material is 1:3, the calcining temperature in the step 3 is 550 ℃, the calcining time is 6h, and the rest conditions are unchanged.
Example 9
Compared with example 1, only the positive electrode material in the step 2 is changed to NCM811, the surfactant is 3-mercaptopropyl trimethoxysilane, the calcining temperature in the step 3 is 550 ℃, the calcining time is 5 hours, and the rest conditions are unchanged.
Example 10
Compared with the example 1, only the positive electrode material in the step 2 is changed to be rich in lithium and manganese, the surfactant is 3-mercaptopropyl trimethoxysilane, the calcining temperature in the step 3 is 550 ℃, the calcining time is 6 hours, and the rest conditions are unchanged.
Comparative example 1
Blank lithium cobaltate without any treatment.
Performance testing
XPS and TEM tests were performed on the lithiated fluoropolymer-coated high-voltage lithium cobalt oxide material prepared in example 1 to verify the lithium fluoride coating and the coating thickness. The results show that the coating layer is lithium fluoride as shown in fig. 1; as shown in fig. 2, the cladding layer was continuous and uniform and had a thickness of about 2.3nm.
The lithiated fluoropolymer-coated high-voltage lithium cobaltate powder prepared in examples 1-3, conductive carbon black and polymer PVDF were mixed at a ratio of 8:1:1, and N-methyl pyrrolidone is used as a dispersing agent. And coating the slurry on an Al foil, and drying to obtain the positive plate. With metallic lithium as negative electrode, 30 μl of 1.0mlipf6 was added to dissolve in EC: emc=3: 7vol% of electrolyte, CR2032 button cell was assembled. All prepared batteries were tested in a New Wired test System with a voltage range of 3.0-4.6V. The first three weeks were activated at a charge-discharge rate of 0.1C and then cycled at 0.5C, with the test environment at room temperature.
As shown in fig. 3, the capacity retention rates of the lithiated fluoropolymer-coated high-voltage lithium cobaltate in example 1, example 2 and example 3 were all significantly improved after 100 weeks of circulation at room temperature compared with those of comparative example 1. Among them, the high-voltage lithium cobaltate material in example 2 exhibited the best first-week charge-discharge specific capacity and cycle performance in examples 1 to 3 and comparative example 1: as shown in fig. 4, the first-week charge-discharge specific capacity was 199mAh/g at 0.1C, the first-week charge-discharge efficiency was 91.34%, the capacity retention after 100 weeks of cycle at 0.5C was 94.56%, and comparative example 1 had only 30.14% capacity retention.
In summary, according to the preparation method of the lithiated fluorine-containing polymer coated cathode material, the fluorine-containing polymer is used as a fluorine source, and the continuous, uniform and thin lithium fluoride coating layer generated by the lithiated fluorine-containing polymer inhibits side reactions of a lithium cobaltate electrolyte interface under high voltage, so that the cycling stability of lithium cobaltate under the voltage can be remarkably improved. The method is simple to operate, low in cost, free of special atmosphere protection, strong in controllability, applicable to other common lithium ion battery anode materials, and wide in application prospect.
The foregoing is merely illustrative of the preferred embodiments of the present invention and is not intended to limit the embodiments and scope of the present invention, and it should be appreciated by those skilled in the art that equivalent substitutions and obvious variations may be made using the teachings of the present invention, which are intended to be included within the scope of the present invention.
Claims (10)
1. The preparation method of the lithiated fluoropolymer coated positive electrode material is characterized by comprising the following steps:
s1, dissolving a fluorine-containing polymer in a solvent I to obtain a solution A; adding metal lithium into the solution A according to a certain proportion, and mixing for a certain time to obtain a solution B containing lithiated fluorine-containing polymer;
s2, dispersing the positive electrode material in a solvent II, adding a surfactant, heating and reacting for a certain time, and centrifugally drying the product to obtain a pretreated positive electrode material;
s3, adding the pretreated positive electrode material into the solution B, uniformly mixing, and removing the solvent to obtain a precursor; and calcining the precursor to obtain the lithiated fluorine-containing polymer coated positive electrode material.
2. The method of claim 1, wherein in step S1, the fluoropolymer comprises one or more of polytetrafluoroethylene, perfluoroethylene propylene copolymer, polytrifluoroethylene, soluble polytetrafluoroethylene, polyvinylidene fluoride-hexafluoropropylene copolymer, hexafluoropropylene-vinylidene fluoride copolymer, polyvinyl fluoride, ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer.
3. The method according to claim 1, wherein in step S1, the concentration of the fluoropolymer in the solution A is 0.1 to 10wt.%, and the molar ratio of the metallic lithium to the fluoropolymer is (0.1 to 10): 1.
4. The method according to claim 1, wherein,
in the step S1, the solvent I is selected from one or more of acetone, butanone, cyclohexanone, cyclopentanone, tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, N-dimethylformamide, dimethylacetamide, hexamethylphosphoric triamide, diethyl carbonate, diethyl phthalate, propylene carbonate, triethyl citrate, triethyl phosphate, and tetramethylurea;
in step S2, the solvent II is selected from one or more of benzene, toluene, acetone, butanone, cyclohexanone, cyclopentanone, tetrahydrofuran, and absolute ethanol.
5. The method according to claim 1, wherein in step S2, the positive electrode material comprises one of lithium cobaltate, lithium iron phosphate, ternary high nickel, and lithium-rich manganese.
6. The method according to claim 1, wherein in step S2, the surfactant comprises one or more of polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, isobutyl triethoxysilane, 3-butyl trimethoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl trimethoxysilane, gamma-ureido propyl triethoxysilane, 3- (2, 3-epoxypropoxy) propyl trimethoxysilane, and monoglyceride stearate.
7. The preparation method according to claim 1, wherein in the step S2, the mass-volume ratio of the pretreated positive electrode material to the surfactant is 1 (1-4) g/mL.
8. The method according to claim 1, wherein in step S3, the molar ratio of the pretreated positive electrode material to the lithiated fluoropolymer is 1 (0.001-0.2); the temperature of the calcination treatment is 300-850 ℃, and the time of the calcination treatment is 3-15 h.
9. A lithiated fluoropolymer-coated positive electrode material, characterized in that said positive electrode material is produced by the production method according to any one of claims 1 to 8.
10. Use of a lithiated fluoropolymer-coated positive electrode material prepared according to the preparation method of any one of claims 1-8 in a lithium ion battery.
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