WO2024046058A1 - 正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池 - Google Patents
正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池 Download PDFInfo
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- WO2024046058A1 WO2024046058A1 PCT/CN2023/111816 CN2023111816W WO2024046058A1 WO 2024046058 A1 WO2024046058 A1 WO 2024046058A1 CN 2023111816 W CN2023111816 W CN 2023111816W WO 2024046058 A1 WO2024046058 A1 WO 2024046058A1
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- Prior art keywords
- iron phosphate
- phosphate
- solution
- regular octahedral
- preparation
- Prior art date
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- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 title claims abstract description 100
- 229910000398 iron phosphate Inorganic materials 0.000 title claims abstract description 94
- 238000002360 preparation method Methods 0.000 title claims abstract description 38
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 title claims abstract description 26
- 239000007774 positive electrode material Substances 0.000 title abstract 2
- 239000000243 solution Substances 0.000 claims abstract description 75
- 239000011259 mixed solution Substances 0.000 claims abstract description 69
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000002002 slurry Substances 0.000 claims abstract description 51
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 50
- 239000010452 phosphate Substances 0.000 claims abstract description 50
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 50
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract description 40
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 34
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 22
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000007800 oxidant agent Substances 0.000 claims abstract description 16
- 238000005406 washing Methods 0.000 claims abstract description 16
- 238000010438 heat treatment Methods 0.000 claims abstract description 12
- 230000001590 oxidative effect Effects 0.000 claims abstract description 11
- 238000001035 drying Methods 0.000 claims abstract description 10
- 229910001448 ferrous ion Inorganic materials 0.000 claims abstract description 10
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910001447 ferric ion Inorganic materials 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims abstract description 6
- 239000003929 acidic solution Substances 0.000 claims abstract description 5
- 238000000926 separation method Methods 0.000 claims abstract description 5
- 238000001354 calcination Methods 0.000 claims abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 68
- 239000012266 salt solution Substances 0.000 claims description 33
- 229910052742 iron Inorganic materials 0.000 claims description 14
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 13
- 239000010406 cathode material Substances 0.000 claims description 13
- 239000000203 mixture Substances 0.000 claims description 13
- 229910052698 phosphorus Inorganic materials 0.000 claims description 13
- 239000011574 phosphorus Substances 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 12
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 11
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 9
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 9
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 9
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 8
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 8
- 229960002089 ferrous chloride Drugs 0.000 claims description 5
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 claims description 5
- 239000004254 Ammonium phosphate Substances 0.000 claims description 4
- 229910002651 NO3 Inorganic materials 0.000 claims description 4
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 4
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 4
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims description 4
- 235000019289 ammonium phosphates Nutrition 0.000 claims description 4
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 4
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 4
- LCPVQAHEFVXVKT-UHFFFAOYSA-N 2-(2,4-difluorophenoxy)pyridin-3-amine Chemical compound NC1=CC=CN=C1OC1=CC=C(F)C=C1F LCPVQAHEFVXVKT-UHFFFAOYSA-N 0.000 claims description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 3
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 3
- 239000011790 ferrous sulphate Substances 0.000 claims description 3
- 235000003891 ferrous sulphate Nutrition 0.000 claims description 3
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims description 3
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 3
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- 229910052760 oxygen Inorganic materials 0.000 claims description 3
- 235000011007 phosphoric acid Nutrition 0.000 claims description 3
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 3
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Substances [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 claims description 3
- 239000001488 sodium phosphate Substances 0.000 claims description 3
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 3
- 235000011008 sodium phosphates Nutrition 0.000 claims description 3
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims 1
- 230000008569 process Effects 0.000 abstract description 7
- 235000021317 phosphate Nutrition 0.000 description 43
- 230000000052 comparative effect Effects 0.000 description 15
- 238000003756 stirring Methods 0.000 description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 239000002243 precursor Substances 0.000 description 12
- 239000000463 material Substances 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 238000001556 precipitation Methods 0.000 description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 9
- -1 ferrous iron ions Chemical class 0.000 description 7
- 238000001914 filtration Methods 0.000 description 7
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000005955 Ferric phosphate Substances 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 229940032958 ferric phosphate Drugs 0.000 description 4
- 229910000399 iron(III) phosphate Inorganic materials 0.000 description 4
- NCNCGGDMXMBVIA-UHFFFAOYSA-L iron(ii) hydroxide Chemical compound [OH-].[OH-].[Fe+2] NCNCGGDMXMBVIA-UHFFFAOYSA-L 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000001000 micrograph Methods 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 229940116007 ferrous phosphate Drugs 0.000 description 3
- 238000006460 hydrolysis reaction Methods 0.000 description 3
- 235000014413 iron hydroxide Nutrition 0.000 description 3
- 229910000155 iron(II) phosphate Inorganic materials 0.000 description 3
- SDEKDNPYZOERBP-UHFFFAOYSA-H iron(ii) phosphate Chemical compound [Fe+2].[Fe+2].[Fe+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O SDEKDNPYZOERBP-UHFFFAOYSA-H 0.000 description 3
- 230000000877 morphologic effect Effects 0.000 description 3
- 239000003002 pH adjusting agent Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 229910021389 graphene Inorganic materials 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000000502 dialysis Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 229960004887 ferric hydroxide Drugs 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- IEECXTSVVFWGSE-UHFFFAOYSA-M iron(3+);oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Fe+3] IEECXTSVVFWGSE-UHFFFAOYSA-M 0.000 description 1
- 229910021506 iron(II) hydroxide Inorganic materials 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
Classifications
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/37—Phosphates of heavy metals
- C01B25/375—Phosphates of heavy metals of iron
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/45—Phosphates containing plural metal, or metal and ammonium
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
- C01P2004/41—Particle morphology extending in three dimensions octahedron-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/11—Powder tap density
-
- 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
Definitions
- the present application relates to the technical field of electrode materials, specifically to an octahedral iron phosphate and its preparation method, lithium iron phosphate cathode material and lithium iron phosphate battery.
- the morphology of the iron phosphate prepared by the existing technology is mainly spherical and flaky, and only a few technologies mention the preparation of regular octahedral iron phosphate.
- An existing preparation method proposes mixing graphene oxide and iron elements at a certain mass ratio, adding deionized water and absolute ethanol during the stirring process, adding H 2 O 2 dropwise during the shaking process, and then adding it under ultrasonic conditions.
- Ultrasonic reaction of phosphate solution, control Fe:P 1:2-2.5.
- dialysis is carried out and a hydrothermal reaction is carried out at 150°C-200°C to obtain a regular octahedral iron phosphate/graphene oxide material.
- One of the purposes of the embodiments of the present application is to provide a regular octahedral iron phosphate and its preparation method, a lithium iron phosphate cathode material and a lithium iron phosphate battery, so as to solve the problem that the existing preparation method in the prior art requires constant temperature conditions or It needs to be strictly controlled at a certain temperature to produce octahedral iron phosphate, and the reaction conditions are relatively harsh technical issues.
- a method for preparing regular octahedral iron phosphate including:
- mixed solution A containing phosphate and ferrous salt, and mixed solution A is an acidic solution
- the pH of mixed solution A is 1.8-2.5;
- the molar ratio of iron element to phosphorus element in mixed solution A is (5:3)-(5:5).
- a method of obtaining mixed solution A includes:
- the concentration of phosphorus element in the phosphate solution is 0.5mol/L-1.5mol/L;
- the pH of the phosphate solution is 4.5-6.5.
- the raw materials used to prepare the phosphate solution include at least one of ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, phosphoric acid, sodium monohydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate.
- the concentration of iron element in the ferrous salt solution is 0.5mol/L-1.5mol/L;
- the raw materials for preparing the ferrous salt solution include at least one of ferrous sulfate, ferrous nitrate, ferrous chloride, iron powder, and iron sheet.
- the oxidizing agent includes at least one of hydrogen peroxide, sodium persulfate, ammonium persulfate, ozone, and oxygen.
- the molar ratio of the iron element in slurry A to the phosphoric acid in the phosphoric acid solution is (5:1)-(5:3);
- the heating temperature is 80°C to 100°C.
- a regular octahedral iron phosphate is prepared by using any of the above preparation methods for regular octahedral iron phosphate.
- a lithium iron phosphate cathode material adopts the above-mentioned regular octahedral iron phosphate.
- a lithium iron phosphate battery includes the above lithium iron phosphate cathode material.
- the acidic mixed solution A makes the ferrous ions insufficient to hydrolyze or react with phosphate to form iron hydroxide or ferrous phosphate precipitation; into the mixed solution A After the oxidant is added and the ferrous iron ions are oxidized into trivalent iron ions, a co-precipitate composed of iron phosphate and iron hydroxide is formed in the system, and then the main component is (FePO 4 ) 4Fe(OH) with a regular octahedral structure.
- the beneficial effects of the regular octahedral iron phosphate provided by the embodiments of the present application are: the tap density is higher than that of iron phosphate with conventional morphology, and it can be used as an ideal precursor for the cathode material of lithium iron phosphate batteries;
- the beneficial effect of the lithium iron phosphate cathode material provided by the embodiments of the present application is that: it is made from the above-mentioned regular octahedral iron phosphate as a precursor material.
- the prepared lithium iron phosphate cathode material is used in lithium iron phosphate batteries and can reduce the cost of lithium iron phosphate batteries. production costs.
- Figure 1 is a scanning electron microscope image of the micromorphology of regular octahedral iron phosphate prepared in Example 1 of the present application;
- Figure 2 is a scanning electron microscope image of the micromorphology of regular octahedral iron phosphate prepared in Example 2 of the present application;
- Figure 3 is a scanning electron microscope image of the micromorphology of regular octahedral iron phosphate prepared in Example 3 of the present application;
- Figure 4 is a scanning electron microscope image of the micromorphology of iron phosphate prepared in Comparative Example 1 of the present application.
- Some embodiments of the present application provide a method for preparing octahedral iron phosphate, including:
- mixed solution A containing phosphate and ferrous salt, and mixed solution A is an acidic solution.
- the acidic mixed solution A makes the ferrous ions insufficient to hydrolyze or react with phosphate to form ferric hydroxide or ferrous phosphate precipitation, maintaining the state of ferrous ions.
- the pH of mixed solution A is 1.8-2.5. If the pH of mixed solution A is higher than 2.5, it may lead to the precipitation of ferrous hydroxide and ferrous phosphate; if the pH of mixed solution A is lower than 1.8, it may cause precipitation. This will lead to the subsequent process of adding oxidants to oxidize ferrous ions into ferric ions. The hydrolysis reaction of ferrous ions is completely inhibited, and all ferric ions are precipitated in the form of ferric phosphate, eventually forming flake-shaped ferric phosphate. Therefore, the pH of mixed solution A is selected to be 1.8-2.5, so that the ferrous ions in the solution can maintain their ionic state before adding the oxidant, and also pave the way for a reaction environment for the next step of the reaction.
- the method of obtaining mixed solution A includes:
- the acidity of mixed solution A can be adjusted in at least three ways:
- the pH adjuster is added to adjust
- the second method is to adjust the pH of the phosphate solution so that after the phosphate solution and the ferrous salt solution are mixed, the pH of the mixed solution A reaches the preset value;
- the third method is to adjust the pH of the ferrous salt solution so that after the phosphate solution and the ferrous salt solution are mixed, the pH of the mixed solution A reaches a preset value.
- the pH of the phosphate solution is 4.5-6.5
- the ferrous salt solution is an acidic solution.
- the pH value of the phosphate solution is adjusted to be in the range of 4.5-6.5. within, thereby controlling the pH value of mixed solution A to be in the range of 1.8-2.5 after the ferrous salt solution and phosphate solution are mixed.
- the pH of the phosphate solution is adjusted by a pH adjuster, which includes at least one of ammonia water, ammonia gas, sodium hydroxide, sulfuric acid, and hydrochloric acid.
- the raw materials used to prepare the phosphate solution include at least one of ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, phosphoric acid, sodium monohydrogen phosphate, sodium dihydrogen phosphate, and sodium phosphate. These raw materials are soluble. Strong, the cations will not form precipitation with the anions in the ferrous salt solution, interfering with the precipitation reaction in the next process.
- the pH value of the phosphate salt raw material liquid should be 4.5-6.5; when the phosphate solution is prepared from phosphorus sources with high pH values such as monoammonium phosphate and ammonium phosphate, sulfuric acid, hydrochloric acid and other substances can be used as pH regulators to adjust the phosphate salt.
- the pH value of the raw material liquid should be 4.5-6.5.
- the pH adjuster of the ferrous salt solution and mixed solution A may also include at least one of ammonia water, ammonia gas, sodium hydroxide, sulfuric acid, and hydrochloric acid.
- the concentration of phosphorus element in the phosphate solution is 0.5 mol/L-1.5 mol/L.
- the concentration of iron element in the ferrous salt solution is 0.5 mol/L-1.5 mol/L.
- the raw materials for preparing the ferrous salt solution include at least one of ferrous sulfate, ferrous nitrate, ferrous chloride, iron powder, and iron sheet. These raw materials can all prepare soluble ferrous salts, wherein, sulfuric acid The anions in ferrous iron, ferrous nitrate, and ferrous chloride will not form precipitates with ammonium ions and sodium ions.
- the molar ratio of iron element to phosphorus element in mixed solution A is (5:3)-(5:5), which provides an element ratio for oxidation and co-precipitation.
- the main component of the precipitate is (FePO 4 ) 4 Fe(OH) 3 ⁇ nH 2 O with a regular octahedral structure.
- the mixed solution A and the oxidant are mixed under stirring conditions, so that the mixed solution A and the oxidant are fully mixed.
- the oxidizing agent includes at least one of hydrogen peroxide, sodium persulfate, ammonium persulfate, ozone, and oxygen.
- the amount of oxidizing agent added is sufficient to oxidize all the ferrous iron in mixed solution A into ferric iron. A slight excess can be used to ensure that the ferrous iron is completely oxidized.
- the molar ratio of the iron element in slurry A to the phosphoric acid in the phosphoric acid solution is (5:1)-(5:3).
- the slurry A is mixed with the phosphoric acid solution, and in the step of carrying out the reaction under heating conditions, the heating temperature is 80°C to 100°C.
- the slurry A and the phosphoric acid solution are mixed under stirring conditions, so that the slurry A and the phosphoric acid solution are fully mixed and evenly contacted.
- steps S20 and S30 are as follows:
- step S20 after the mixed solution A and the oxidizing agent are mixed,
- step S30 after adding phosphoric acid, the temperature is raised for conversion
- the solid-liquid separation treatment, washing treatment, and drying treatment methods and equipment can be common methods or equipment in the existing iron phosphate preparation technology.
- the preparation method of regular octahedral iron phosphate controls the ratio of iron element to phosphorus element in the mixed solution A to (5:3)-(5:5).
- the precipitated (FePO 4 ) 4 Fe(OH) 3 ⁇ nH 2 O is a regular octahedral precursor material.
- the Fe(OH) 3 component in the octahedral precursor material is converted into FePO 4 .
- the preparation method of regular octahedral iron phosphate does not require constant temperature conditions, nor does it need to control the temperature at a specific temperature, and avoids the harsh conditions of high temperature, high pressure, and long cycles of the hydrothermal method/solvent method.
- the reaction conditions at the same time greatly reduce the amount of phosphorus source, significantly reducing the production cost of octahedral iron phosphate, and prepare octahedral iron phosphate through a coprecipitation method with relatively mild reaction conditions.
- the embodiments of the present application also provide an octahedral iron phosphate made by using the above preparation method of the regular octahedral iron phosphate.
- the tap density of the regular octahedral iron phosphate provided by the embodiments of the present application can reach 0.8 g/cm 3 -1.2g. /cm 3 , which is higher than the tap density of iron phosphate with conventional morphology, can be used as an ideal precursor for lithium iron phosphate cathode materials, and has better filtration and washing performance, that is, the regular octahedral iron phosphate in the embodiment of the present application is During washing, the filtration speed is faster, the washing effect is better, and it is more water-saving.
- the washing water consumption of regular octahedral iron phosphate is about 30m 3 /t
- the washing water consumption of conventional iron phosphate is about 40m 3 /t-70 m 3 /t.
- octahedral iron phosphate can be used as a precursor material to prepare lithium iron phosphate cathode materials.
- the prepared lithium iron phosphate cathode materials can be used in lithium iron phosphate batteries, which can reduce the production cost of lithium iron phosphate batteries.
- the preparation method of regular octahedral iron phosphate includes the following steps:
- the preparation method of iron phosphate in this comparative example is a preparation method of conventional morphological iron phosphate.
- the steps of comparative example 1 are similar to those of Example 1.
- the proportions of reaction raw materials are the same.
- the ferrous salt solution and the phosphate solution are mixed into the mixed solution.
- the molar ratio of iron element to phosphoric acid is 5:4, and the added phosphoric acid satisfies the condition.
- the molar ratio of iron element to phosphoric acid 5:2.
- Example 1 The difference between this comparative example and Example 1 is that the pH value of the phosphate solution is not adjusted.
- the preparation method of iron phosphate in this comparative example includes the following steps:
- This comparative example is a preparation method of conventional morphological iron phosphate.
- the steps of this comparative example are similar to those of Example 1.
- the difference from Example 1 is that the iron element in the mixed solution A obtained by mixing the ferrous salt solution and the phosphate solution is mixed with the iron element in the mixed solution A.
- the molar ratio of phosphorus element is 5:5.8.
- the preparation method of iron phosphate in this comparative example includes the following steps:
- iron phosphate After filtering, washing, and drying slurry B, iron phosphate is obtained.
- the iron phosphate obtained has a conventional morphology and a non-octahedral morphology.
- Examples 1 to 4 can all prepare regular octahedral iron phosphate, and the iron phosphates prepared in Comparative Example 1 and Comparative Example 2 are all iron phosphates with conventional morphology.
- the ferric phosphate obtained in Comparative Example 1 showed a regular morphology, which may be because the pH value of the phosphate solution was not regulated, and the pH of the ferrous salt solution was not regulated either.
- the pH of mixed solution A was lower than 1.8, and the pH of the reaction system The value is low. At a low reaction pH value, the hydrolysis of ferric ions is inhibited. Most of the precipitates generated in slurry A are FePO 4 ⁇ nH 2 O.
- the morphology of the precursor material affects the final phosphoric acid.
- the morphology of the finished iron product is that without the production of the octahedral precursor material (FePO 4 ) 4 Fe(OH) 3 ⁇ nH 2 O, the final iron phosphate cannot obtain the octahedral morphology.
- the iron phosphate obtained in Comparative Example 2 is similar to Comparative Example 1 and does not have a regular octahedral morphology.
- the reason may be that the molar ratio of iron element and phosphorus element in mixed solution A is not controlled within the range of 5:3-5:5.
- iron ions preferentially combine with phosphate to form iron phosphate precipitates, and the amount of Fe(OH) 3 formed is small, making it difficult to form a regular octahedral structure; when there is too much iron, the hydrolysis of iron ions will produce too much Fe(OH) ) 3 colloid, which causes the precursor material to have a rice-like amorphous morphology, making it impossible to obtain iron phosphate with a regular octahedral morphology.
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Abstract
本申请公开一种正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池,正八面体磷酸铁的制备方法包括:获得含有磷酸盐和亚铁盐的混合溶液A,混合溶液A为酸性溶液;将混合溶液A与氧化剂混合,混合溶液A中的亚铁离子被氧化成三价铁离子,得到浆料A;将浆料A与磷酸溶液混合,在加热条件下进行反应,得到浆料B;将浆料B进行固液分离处理、洗涤处理、干燥处理和煅烧处理后,得到正八面体磷酸铁。
Description
本申请要求于2022年09月02日在中国专利局提交的、申请号为202211070666.5、发明名称为“正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
本申请涉及电极材料技术领域,具体涉及一种正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池。
现有技术所制备的磷酸铁,其形貌以球形形貌和片状形貌为主,仅有少量技术提及了正八面体磷酸铁的制备。
现有的一种制备方法提出将氧化石墨烯与铁元素按一定质量比混合,在搅拌过程中加入去离子水和无水乙醇,震荡过程中滴加H
2O
2,之后在超声条件下加入磷酸盐溶液超声反应,控制Fe:P=1:2-2.5。之后进行透析,在150℃-200℃下进行水热反应,从而获得正八面体型磷酸铁/氧化石墨烯材料。
还有一种制备方法采用以金属表面处理的副产物磷化渣为原料,与草酸等物质混合进行反应制备羟基磷酸铁,进而制备磷酸铁,此方法需要严格控制反应温度,过高或过低的温度都无法制得正八面体磷酸铁,例如100℃时,所制成的磷酸铁呈短棒状;150℃时,所制成的磷酸铁呈球状、短棒状;200℃时所制成的磷酸铁虽呈正八面体状,但棱角不明、表面破碎严重,唯有180℃下所制备的磷酸铁才呈现出完整的正八面体形貌。
现有的制备方法需要恒温条件或者需要严格控制在一个温度下才能制成正八面体磷酸铁,反应条件比较苛刻。
本申请实施例的目的之一在于:提供一种正八面体磷酸铁及其制备方法、磷酸铁锂正极材料和磷酸铁锂电池,以解决现有技术中存在的现有的制备方法需要恒温条件或者需要严格控制在一个温度下才能制成正八面体磷酸铁,反应条件比较苛刻的技术问题。
本申请实施例采用的技术方案是:
第一方面,提供了一种正八面体磷酸铁的制备方法,包括:
获得含有磷酸盐和亚铁盐的混合溶液A,混合溶液A为酸性溶液;
将混合溶液A与氧化剂混合,混合溶液A中的亚铁离子被氧化成三价铁离子,得到浆料A;
将浆料A与磷酸溶液混合,在加热条件下进行反应,得到浆料B;
将浆料B进行固液分离处理、洗涤处理、干燥处理和煅烧处理后,得到正八面体磷酸铁。
在一个实施例中,混合溶液A的pH为1.8-2.5;
和/或,混合溶液A中的铁元素与磷元素的摩尔比为(5:3)-(5:5)。
在一个实施例中,获得混合溶液A的方法包括:
获得磷酸盐溶液;
将磷酸盐溶液和亚铁盐溶液混合,得到混合溶液A。
在一个实施例中,磷酸盐溶液中磷元素的浓度为0.5mol/L-1.5mol/L;
和/或,磷酸盐溶液的pH为4.5-6.5。
在一个实施例中,制备磷酸盐溶液所采用的原料包括磷酸一氢铵、磷酸二氢铵、磷酸铵、磷酸、磷酸一氢钠、磷酸二氢钠、磷酸钠中的至少一种。
在一个实施例中,亚铁盐溶液中铁元素的浓度为0.5mol/L-1.5mol/L;
和/或,制备亚铁盐溶液的原料包括硫酸亚铁、硝酸亚铁、氯化亚铁、铁粉、铁皮中的至少一种。
在一个实施例中,氧化剂包括双氧水、过硫酸钠、过硫酸铵、臭氧、氧气中的至少一种。
在一个实施例中,浆料A中的铁元素与磷酸溶液中的磷酸的摩尔比为(5:1)-(5:3);
和/或,将浆料A与磷酸溶液混合,在加热条件下进行反应的步骤中,加热的温度为80℃-100℃。
第二方面,一种正八面体磷酸铁,采用上述任一所述的正八面体磷酸铁的制备方法制成。
第三方面,一种磷酸铁锂正极材料,采用上述正八面体磷酸铁。
第四方面,一种磷酸铁锂电池,包括上述磷酸铁锂正极材料。
本申请实施例提供的正八面体磷酸铁的制备方法的有益效果在于:酸性的混合溶液A使亚铁离子不足以水解或与磷酸根反应形成氢氧化铁或磷酸亚铁沉淀;向混合溶液A中添加氧化剂,二价铁离子被氧化成三价铁离子后,体系中同时形成了由磷酸铁和氢氧化铁组成的共沉淀,进而形成主要成分为具有正八面体结构的(FePO
4)4Fe(OH)
3·nH
2O的沉淀;此后,再向浆料A中添加磷酸溶液,加热条件下,使得形貌为正八面体(FePO
4)4Fe(OH)
3·nH
2O前体材料中的Fe(OH)
3被转化为FePO
4,在转化过程中,沉淀的整体结构框架未发生改变,始终保持着正八面体结构;
本申请实施例提供的正八面体磷酸铁的有益效果在于:振实密度高于常规形貌的磷酸铁的振实密度,可作为磷酸铁锂电池正极材料的理想前驱体;
本申请实施例提供的磷酸铁锂正极材料的有益效果在于:以上述正八面体磷酸铁作为前驱体材料制成,制成的磷酸铁锂正极材料应用于磷酸铁锂电池,可降低磷酸铁锂电池的生产成本。
为了更清楚地说明本申请实施例中的技术方案,下面将对实施例或示范性技术描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本申请的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其它的附图。
图1为本申请实施例1制备的正八面体磷酸铁的微观形貌的扫描电镜图;
图2为本申请实施例2制备的正八面体磷酸铁的微观形貌的扫描电镜图;
图3为本申请实施例3制备的正八面体磷酸铁的微观形貌的扫描电镜图;
图4为本申请对比例1制备的磷酸铁的微观形貌的扫描电镜图。
为了使本申请的目的、技术方案及优点更加清楚明白,以下结合附图及实施例,对本申请进行进一步详细说明。应当理解,此处所描述的具体实施例仅用以解释本发明,并不用于限定本申请。
需说明的是,当部件被称为“固定于”或“设置于”另一个部件,它可以直接在另一个部件上或者间接在该另一个部件上。当一个部件被称为是“连接于”另一个部件,它可以是直接或者间接连接至该另一个部件上。术语“上”、“下”、“左”、“右”等指示的方位或位置关系为基于附图所示的方位或位置关系,仅是为了便于描述,而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作,因此不能理解为对本申请的限制,对于本领域的普通技术人员而言,可以根据具体情况理解上述术语的具体含义。术语“第一”、“第二”仅用于便于描述目的,而不能理解为指示或暗示相对重要性或者隐含指明技术特征的数量。“多个”的含义是两个或两个以上,除非另有明确具体的限定。
为了说明本申请所提供的技术方案,以下结合具体附图及实施例进行详细说明。
本申请的一些实施例提供了一种正八面体磷酸铁的制备方法,包括:
S10:获得含有磷酸盐与亚铁盐溶的混合溶液A,混合溶液A为酸性溶液。
酸性的混合溶液A使亚铁离子不足以水解或与磷酸根反应形成氢氧化铁或磷酸亚铁沉淀,保持亚铁离子的状态。
可选地,混合溶液A的pH为1.8-2.5,若混合溶液A的pH高于2.5,可能会导致氢氧化亚铁、磷酸亚铁沉淀的产生;若混合溶液A的pH低于1.8,可能会导致后续在加入氧化剂将亚铁离子氧化成铁离子的过程中,铁离子的水解反应完全受到抑制,全部的铁离子均以磷酸铁的形式沉淀,最终形成片状形貌的磷酸铁。所以混合溶液A的pH选为1.8-2.5,令溶液的亚铁离子在未加入氧化剂之前可以保持离子状态,亦为下一步工序的反应做好反应环境铺垫。
可选地,获得混合溶液A的方法包括:
获得磷酸盐溶液;
将磷酸盐溶液和亚铁盐溶液混合,得到混合溶液A。
如此,混合溶液A的酸性可以通过至少三种方式进行调节:
第一种方式,磷酸盐溶液与亚铁盐溶液混合后,通过添加pH调节剂进行调节;
第二种方式,调节磷酸盐溶液的pH,使磷酸盐溶液与亚铁盐溶液混合后,混合溶液A的pH达到预设值;
第三种方式,调节亚铁盐溶液的pH,使磷酸盐溶液与亚铁盐溶液混合后,混合溶液A的pH达到预设值。
在一个实施例中,磷酸盐溶液的pH为4.5-6.5,亚铁盐溶液为酸性溶液,在亚铁盐溶液不调节pH的情况下,通过调控磷酸盐溶液的pH值处于4.5-6.5的范围内,从而控制亚铁盐溶液和磷酸盐溶液混合之后,混合溶液A的pH值处于1.8-2.5范围。
磷酸盐溶液的pH通过pH调节剂进行调节,pH调节剂包括氨水、氨气、氢氧化钠、硫酸、盐酸中的至少一种。
可选地,制备磷酸盐溶液所采用的原料包括磷酸一氢铵、磷酸二氢铵、磷酸铵、磷酸、磷酸一氢钠、磷酸二氢钠、磷酸钠中的至少一种,该些原料可溶性强,阳离子不会与亚铁盐溶液中的阴离子形成沉淀,干扰下一工序的沉淀反应。
当磷酸盐溶液需要调节pH时,例如磷酸盐溶液由磷酸二氢铵、磷酸等低pH值的磷源配制而成时,可选用氨水、氨气、氢氧化钠等物质作为pH调节剂,调节磷盐原料液的pH值至4.5-6.5;当磷酸盐溶液由磷酸一铵、磷酸铵等高pH值的磷源配制而成时,可选用硫酸、盐酸等物质作为pH调节剂,调节磷盐原料液的pH值至4.5-6.5。
可以理解地,亚铁盐溶液和混合溶液A的pH调节剂也可以包括氨水、氨气、氢氧化钠、硫酸、盐酸中的至少一种。
可选地,磷酸盐溶液中磷元素的浓度为0.5mol/L-1.5mol/L。
可选地,亚铁盐溶液中铁元素的浓度为0.5mol/L-1.5mol/L。
可选地,制备亚铁盐溶液的原料包括有硫酸亚铁、硝酸亚铁、氯化亚铁、铁粉、铁皮中的至少一种,该些原料均可制备可溶性亚铁盐,其中,硫酸亚铁、硝酸亚铁、氯化亚铁中的阴离子均不会与铵离子、钠离子形成沉淀。
可选地,混合溶液A中的铁元素与磷元素的摩尔比为(5:3)-(5:5),为氧化、共沉淀提供元素配比,通过控制铁元素与磷元素的摩尔比在(5:3)-(5:5),确保在步骤S20加入氧化剂后,形成沉淀的主要成分为具有正八面体结构的(FePO
4)
4Fe(OH)
3·nH
2O。
S20:将混合溶液A与氧化剂混合,混合溶液中亚铁离子被氧化成三价铁离子,得到浆料A。
向混合溶液A中添加氧化剂,二价铁离子被氧化成三价铁离子后,体系中同时形成了由磷酸铁和氢氧化铁组成的共沉淀,进而形成包括具有正八面体结构的(FePO
4)
4Fe(OH)
3·nH
2O的沉淀。
可以理解地,混合溶液A与氧化剂在搅拌条件下进行混合,使混合溶液A和氧化剂充分混合。
可选地,氧化剂包括双氧水、过硫酸钠、过硫酸铵、臭氧、氧气中的至少一种。
氧化剂加入的量足够将混合溶液A中亚铁全部氧化成三价铁,可以稍微过量,以确保亚铁被完全氧化。
S30:将浆料A与磷酸溶液混合,在加热条件下进行反应,得到浆料B。
向浆料A中添加磷酸溶液,加热条件下,使得形貌为正八面体(FePO
4)
4Fe(OH)
3·nH
2O前体材料中的Fe(OH)
3被转化为FePO
4,在转化过程中,沉淀的整体结构框架未发生改变,始终保持着正八面体结构。
可选地,浆料A中的铁元素与磷酸溶液中的磷酸的摩尔比为(5:1)-(5:3)。
可选地,将浆料A与磷酸溶液混合,在加热条件下进行反应的步骤中,加热的温度为80℃-100℃。
可以理解地,浆料A与磷酸溶液在搅拌条件下进行混合,使浆料A与磷酸溶液充分混合,接触均匀。
步骤S20和S30的反应原理如下:
步骤S20中,混合溶液A和氧化剂混合后,
① Fe
3++H
2O→Fe(OH)
2++H
+,
② Fe(OH)
2++H
2O→Fe(OH)
2++H
+,
③ Fe
3++2H
2PO
4
-→Fe(H
2PO
4)
2+,
④ Fe(H
2PO
4)
2++3H
2O+Fe(OH)
2+→2FePO
4·2H
2O+2H
+,
⑤ Fe(OH)
2++H
2O→Fe(OH)
3+2H
+,
由(①+②+③+④)*2可得
4Fe
3++4H
2PO
4-+10H
2O→4FePO
4·2H
2O+8H
+,
由(①+②+③)可得
Fe
3++3H
2O→Fe(OH)
3+3H
+,
总方程式:(①+②+③+④)*2+(①+②+③)
即:5Fe
3++4H
2PO
4
-+(8n-4)H
2O→[Fe(PO
4)]
4Fe(OH)
3·nH
2O+11H
+。
步骤S30中,在加入磷酸后、升温转化,
[Fe(PO
4)]
4Fe(OH)
3·nH
2O+H
3PO
4→5FePO
4·2H
2O+mH
2O。
S40:将浆料B进行固液分离处理、洗涤处理、干燥处理和煅烧处理后,得到正八面体磷酸铁。
固液分离处理、洗涤处理、干燥处理的方式及设备可以为现有磷酸铁制备技术中通用的方式或设备。
本申请实施例提供的正八面体磷酸铁的制备方法,控制混合溶液A中铁元素与磷元素的配比为(5:3)-(5:5),通过与混合溶液A的pH值调控的共同作用,准确控制反应所生成沉淀(FePO
4)
4Fe(OH)
3·nH
2O的分子式和形貌结构,沉淀(FePO
4)
4Fe(OH)
3·nH
2O为正八面体前体材料,然后再通过添加磷酸溶液升温转化,将正八面体前体材料中Fe(OH)
3组分转变成FePO
4。
与现有技术相比,本申请提供的正八面体磷酸铁的制备方法,过程无需恒温条件,也无需将温度控制在一个特定温度,避免了水热法/溶剂法高温、高压、长周期等苛刻的反应条件,同时大幅度降低了磷源的用量,显著降低了正八面体磷酸铁的生产成本,通过反应条件较为温和的共沉淀法制备出正八面体磷酸铁。
本申请实施例还提供了一种采用上述正八面体磷酸铁的制备方法制成的正八面体磷酸铁,本申请实施例提供的正八面体磷酸铁的振实密度可达0.8 g/cm
3-1.2g/cm
3,高于常规形貌的磷酸铁的振实密度,可作为磷酸铁锂正极材料的理想前驱体,并且具有更好的过滤、洗涤性能,即本申请实施例的正八面体磷酸铁在洗涤时过滤速度更快、洗涤效果好、更为节水,例如在同样的洗涤方式和设备下,正八面体磷酸铁洗水用量约30m
3/t,常规形貌磷酸铁洗水用量约40m
3/t-70 m
3/t。
本申请实施例正八面体磷酸铁可作为前驱体材料,制备磷酸铁锂正极材料,制成的磷酸铁锂正极材料应用于磷酸铁锂电池,可降低磷酸铁锂电池的生产成本。
以下通过多个实施例来举例说明。
实施例1
正八面体磷酸铁的制备方法包括以下步骤:
S01:称量460g磷酸二氢铵溶解,并加入氨水调节溶液的pH值至5.0,获得4L的磷酸盐溶液。
S02:称量1390g七水硫酸亚铁溶解并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液在搅拌条件下进行混合,获得混合溶液A,混合溶液A的pH为2.3。
S04:在持续搅拌条件下,将300g 30wt%的双氧水溶液缓慢滴加至混合溶液A中,反应30 min,获得浆料A。
S05:向浆料A中加入230g 85wt%磷酸溶液,之后升温至90℃,并保温2 h,获得白色浆料B。
S06:将浆料B经过滤、洗涤、烘干处理后,获得正八面体磷酸铁,正八面体磷酸铁的振实密度为0.85 g/cm
3,本实施例所制正八面体磷酸铁的微观形貌如图1所示。
实施例2
本实施例正八面体磷酸铁的制备方法,包括以下步骤:
S01:称量460g的85wt%磷酸溶液,加入氢氧化钠调节溶液pH值至4.8,获得4L的磷酸盐溶液。
S02:称量810g的四水氯化亚铁溶解,并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液在搅拌条件进行混合,获得混合溶液A,混合溶液A的pH为2.2。
S04:在持续搅拌条件下,将460g的20wt%双氧水溶液缓慢滴加至混合溶液A中,之后反应30 min,获得浆料A。
S05:向浆料A中加入200g的85wt%磷酸溶液,之后升温至85℃,并保温2h,获得白色浆料B。
S06:将浆料B经过滤、洗涤、烘干处理后,获得正八面体磷酸铁,正八面体磷酸铁的振实密度为0.93 g/cm3,本实施例所制正八面体磷酸铁的微观形貌如图2所示。
实施例3
本实施例正八面体磷酸铁的制备方法包括以下步骤:
S01:称量528g的磷酸一氢铵溶解,并加入硫酸调节pH值至6.5,获得4L的磷酸盐溶液。
S02:称量1390g的七水硫酸亚铁溶解并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液混合,搅拌均匀,获得混合溶液A,混合溶液A的pH为2.5。
S04:在持续搅拌的条件下,将300g 30wt%的双氧水溶液缓慢滴加至混合溶液A中,之后反应30 min,获得浆料A。
S05:向浆料A中加入300g 80wt%磷酸溶液,之后升温至92℃并保温2 h,获得白色浆料B。
S06:浆料B经过滤、洗涤、烘干后,获得正八面体磷酸铁,正八面体磷酸铁的振实密度为1.11 g/cm
3,本实施例所制正八面体磷酸铁的微观形貌如图3所示。
实施例4
本实施例正八面体磷酸铁的制备方法包括以下步骤:
S01:称量460g的磷酸二氢铵溶于水,并加入氨水调节溶液pH值至5.5,获得4L的磷酸盐溶液。
S02:称量1390g的七水硫酸亚铁溶于水,并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液混合,搅拌均匀,获得混合溶液A,混合溶液A的pH为2.4。
S04:在持续搅拌条件下,将溶解有600 g过硫酸铵的溶液缓慢滴加至混合溶液A中,之后反应30 min,获得浆料A。
S05:向浆料A中加入340g的85wt%磷酸溶液,之后升温至90℃,并保温2 h,获得白色浆料B。
S06:将浆料B经过滤、洗涤、烘干处理后,获得正八面体磷酸铁,正八面体磷酸铁的振实密度为1.07g/cm
3。
对比例1
本对比例的磷酸铁的制备方法为常规形貌磷酸铁的制备方法,对比例1与实施例1的步骤相似,反应原料的配比相同,亚铁盐溶液与磷酸盐溶液混合所得混合溶液中的摩尔比为5:4,添加的磷酸满足条件铁元素与磷酸的摩尔比为=5:2。
本对比例与实施例1的区别在于:不对磷酸盐溶液的pH值进行调控。
本对比例磷酸铁的制备方法包括以下步骤:
S01:称量460g的磷酸二氢铵溶解,获得4L的磷酸盐溶液,磷酸盐溶液的pH值为3.92。
S02:称量1390g的七水硫酸亚铁溶解并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液混合,搅拌均匀,获得混合溶液A,混合溶液A的pH为1.5。
S04:在持续搅拌的条件下,将300g的30wt%的双氧水溶液缓慢滴加至混合溶液A中,之后反应30 min,获得浆料A。
S05:向浆料A中加入230g的85wt%磷酸溶液,之后升温至90℃,并保温2 h,获得白色浆料B。
S06:将浆料B经过滤、洗涤、烘干处理后,获得磷酸铁,磷酸铁的形貌如图4所示。
对比例2
本对比例为常规形貌磷酸铁的制备方法,本对比例与实施例1的步骤相似,与实施例1的区别在于,亚铁盐溶液与磷酸盐溶液混合所得混合溶液A中的铁元素与磷元素的摩尔比为5:5.8。
本对比例磷酸铁的制备方法包括以下步骤:
S01:称量534g的磷酸二氢铵溶解,加入氨水调节pH至5.0,获得4L的磷酸盐溶液。
S02:称量1112g的七水硫酸亚铁溶解,并定容至4L,获得亚铁盐溶液。
S03:将磷酸盐溶液和亚铁盐溶液混合,搅拌均匀,获得混合溶液A,混合溶液A的pH为2.1。
S04:在持续搅拌的条件下,将300g的30wt%双氧水溶液缓慢滴加至混合溶液A中,之后反应30 min,获得浆料A。
S05:向浆料A中加入184g的85wt%磷酸溶液,之后升温至90℃,并保温2 h,获得白色浆料B。
S06:将浆料B经过滤、洗涤、烘干处理后,获得磷酸铁,所获得的磷酸铁为常规形貌,非正八面体形貌。
可知,实施例1至4均能够制备正八面体磷酸铁,对比例1和对比例2制成的磷酸铁均为常规形貌的磷酸铁。
对比例1获得的磷酸铁呈现出常规形貌,可能是因为未对磷酸盐溶液的pH值进行调控,亚铁盐溶液的pH也没有调控,混合溶液A的pH低于1.8,反应体系的pH值较低,在较低的反应pH值下,三价铁离子的水解受到抑制,浆料A中所生成的沉淀绝大部分为FePO
4·nH
2O,前体材料的形貌影响最终磷酸铁成品的形貌,在没有正八面体前体材料(FePO
4)
4Fe(OH)
3·nH
2O产生的前提下,最终磷酸铁无法获得正八面体的形貌。
对比例2获得的磷酸铁与对比例1相似,并非正八面体形貌,原因可能是混合溶液A中的铁元素和磷元素的摩尔比未控制在5:3-5:5的范围内,无法形成正八面体的前体材料(FePO
4)
4Fe(OH)
3·nH
2O。当铁元素过少时,铁离子优先与磷酸根形成磷酸铁沉淀,形成的Fe(OH)
3量较少,难以成型正八面体结构;当铁元素过多时,铁离子水解会产生过多Fe(OH)
3胶体,导致前体材料呈现为米粒状的无定型形貌,进而无法获得正八面体形貌的磷酸铁。
以上仅为本申请的可选实施例而已,并不用于限制本申请。对于本领域的技术人员来说,本申请可以有各种更改和变化。凡在本申请的精神和原则之内,所作的任何修改、等同替换、改进等,均应包含在本申请的权利要求范围之内。
Claims (16)
- 一种正八面体磷酸铁的制备方法,其特征在于,包括:获得含有磷酸盐和亚铁盐的混合溶液A,所述混合溶液A为酸性溶液;将所述混合溶液A与氧化剂混合,所述混合溶液A中的亚铁离子被氧化成三价铁离子,得到浆料A;将所述浆料A与磷酸溶液混合,在加热条件下进行反应,得到浆料B;将所述浆料B进行固液分离处理、洗涤处理、干燥处理和煅烧处理后,得到正八面体磷酸铁。
- 根据权利要求1所述的正八面体磷酸铁的制备方法,其特征在于,所述混合溶液A的pH为1.8-2.5。
- 根据权利要求1或2所述的正八面体磷酸铁的制备方法,其特征在于,所述混合溶液A中的铁元素与磷元素的摩尔比为(5:3)-(5:5)。
- 根据权利要求1-3任一项所述的正八面体磷酸铁的制备方法,其特征在于,获得所述混合溶液A的方法包括:获得磷酸盐溶液;将所述磷酸盐溶液和亚铁盐溶液混合,得到所述混合溶液A。
- 根据权利要求4所述的正八面体磷酸铁的制备方法,其特征在于,所述磷酸盐溶液中磷元素的浓度为(0.5-1.5)mol/L。
- 根据权利要求4或5所述的正八面体磷酸铁的制备方法,其特征在于,所述磷酸盐溶液的pH为4.5-6.5。
- 根据权利要求4-6任一项所述的正八面体磷酸铁的制备方法,其特征在于,制备所述磷酸盐溶液所采用的原料包括磷酸一氢铵、磷酸二氢铵、磷酸铵、磷酸、磷酸一氢钠、磷酸二氢钠、磷酸钠中的至少一种。
- 根据权利要求4-7任一项所述的正八面体磷酸铁的制备方法,其特征在于,所述亚铁盐溶液中铁元素的浓度为(0.5-1.5)mol/L。
- 根据权利要求4-8任一项所述的正八面体磷酸铁的制备方法,其特征在于,制备所述亚铁盐溶液所采用的原料包括硫酸亚铁、硝酸亚铁、氯化亚铁、铁粉、铁皮中的至少一种。
- 根据权利要求1-9任一项所述的正八面体磷酸铁的制备方法,其特征在于,所述氧化剂包括双氧水、过硫酸钠、过硫酸铵、臭氧、氧气中的至少一种。
- 根据权利要求1-10任一项所述的正八面体磷酸铁的制备方法,其特征在于,所述浆料A中的铁元素与所述磷酸溶液中的磷酸的摩尔比为(5:1)-(5:3)。
- 根据权利要求1-12任一项所述的正八面体磷酸铁的制备方法,其特征在于,所述将浆料A与磷酸溶液混合,在加热条件下进行反应的步骤中,加热的温度为80℃-100℃。
- 一种正八面体磷酸铁,其特征在于:采用权利要求1至12任一所述的正八面体磷酸铁的制备方法制成。
- 根据权利要求13所述的正八面体磷酸铁,其特征在于,所述正八面体磷酸铁的振实密度为0.8 g/cm 3-1.2g/cm 3。
- 一种磷酸铁锂正极材料,其特征在于:采用权利要求13或14所述的正八面体磷酸铁制成。
- 一种磷酸铁锂电池,其特征在于:包括权利要求15所述的磷酸铁锂正极材料。
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