CN115196653A - Coated prussian bletilla striata and preparation method and application thereof - Google Patents
Coated prussian bletilla striata and preparation method and application thereof Download PDFInfo
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- CN115196653A CN115196653A CN202210914516.1A CN202210914516A CN115196653A CN 115196653 A CN115196653 A CN 115196653A CN 202210914516 A CN202210914516 A CN 202210914516A CN 115196653 A CN115196653 A CN 115196653A
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- prussian white
- coated
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- potassium
- white
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- 238000002360 preparation method Methods 0.000 title abstract description 33
- 241001313857 Bletilla striata Species 0.000 title abstract description 4
- 238000005406 washing Methods 0.000 claims abstract description 71
- 239000011734 sodium Substances 0.000 claims abstract description 56
- 239000000126 substance Substances 0.000 claims abstract description 54
- 239000012266 salt solution Substances 0.000 claims abstract description 35
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims abstract description 30
- 229910001415 sodium ion Inorganic materials 0.000 claims abstract description 29
- 229910001414 potassium ion Inorganic materials 0.000 claims abstract description 19
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims abstract description 12
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 37
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 37
- 235000011151 potassium sulphates Nutrition 0.000 claims description 37
- 238000001035 drying Methods 0.000 claims description 28
- 238000000034 method Methods 0.000 claims description 23
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 20
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 11
- 239000001103 potassium chloride Substances 0.000 claims description 10
- 235000011164 potassium chloride Nutrition 0.000 claims description 10
- 230000009471 action Effects 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 235000010333 potassium nitrate Nutrition 0.000 claims description 5
- 239000004323 potassium nitrate Substances 0.000 claims description 5
- 239000001508 potassium citrate Substances 0.000 claims description 2
- 229960002635 potassium citrate Drugs 0.000 claims description 2
- QEEAPRPFLLJWCF-UHFFFAOYSA-K potassium citrate (anhydrous) Chemical compound [K+].[K+].[K+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O QEEAPRPFLLJWCF-UHFFFAOYSA-K 0.000 claims description 2
- 235000011082 potassium citrates Nutrition 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 47
- 238000010521 absorption reaction Methods 0.000 abstract description 7
- 238000004146 energy storage Methods 0.000 abstract description 3
- 239000000243 solution Substances 0.000 description 136
- 238000006243 chemical reaction Methods 0.000 description 89
- 239000012065 filter cake Substances 0.000 description 63
- 239000002002 slurry Substances 0.000 description 47
- 239000011247 coating layer Substances 0.000 description 43
- 238000000576 coating method Methods 0.000 description 40
- 239000000463 material Substances 0.000 description 38
- 239000011248 coating agent Substances 0.000 description 37
- 239000000264 sodium ferrocyanide Substances 0.000 description 35
- GTSHREYGKSITGK-UHFFFAOYSA-N sodium ferrocyanide Chemical compound [Na+].[Na+].[Na+].[Na+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] GTSHREYGKSITGK-UHFFFAOYSA-N 0.000 description 35
- 235000012247 sodium ferrocyanide Nutrition 0.000 description 35
- 239000001509 sodium citrate Substances 0.000 description 34
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 34
- 229940099596 manganese sulfate Drugs 0.000 description 27
- 239000011702 manganese sulphate Substances 0.000 description 27
- 235000007079 manganese sulphate Nutrition 0.000 description 27
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 27
- 239000000047 product Substances 0.000 description 24
- 238000003756 stirring Methods 0.000 description 23
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 22
- 230000032683 aging Effects 0.000 description 19
- 230000000052 comparative effect Effects 0.000 description 18
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 15
- 238000001914 filtration Methods 0.000 description 15
- 229910052708 sodium Inorganic materials 0.000 description 15
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 12
- 239000012535 impurity Substances 0.000 description 12
- 230000003647 oxidation Effects 0.000 description 12
- 238000007254 oxidation reaction Methods 0.000 description 12
- 229910052700 potassium Inorganic materials 0.000 description 12
- 229960003975 potassium Drugs 0.000 description 12
- 239000011591 potassium Substances 0.000 description 12
- 239000012452 mother liquor Substances 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 11
- 238000001556 precipitation Methods 0.000 description 11
- 238000005086 pumping Methods 0.000 description 11
- 230000002194 synthesizing effect Effects 0.000 description 11
- 239000012792 core layer Substances 0.000 description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 9
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 238000001878 scanning electron micrograph Methods 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 239000008139 complexing agent Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 229910003321 CoFe Inorganic materials 0.000 description 4
- 239000010406 cathode material Substances 0.000 description 4
- 239000010405 anode material Substances 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 229940044175 cobalt sulfate Drugs 0.000 description 3
- 229910000361 cobalt sulfate Inorganic materials 0.000 description 3
- KTVIXTQDYHMGHF-UHFFFAOYSA-L cobalt(2+) sulfate Chemical compound [Co+2].[O-]S([O-])(=O)=O KTVIXTQDYHMGHF-UHFFFAOYSA-L 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000011790 ferrous sulphate Substances 0.000 description 3
- 235000003891 ferrous sulphate Nutrition 0.000 description 3
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 3
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 3
- 239000011572 manganese Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910017052 cobalt Inorganic materials 0.000 description 2
- 239000010941 cobalt Substances 0.000 description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 244000241838 Lycium barbarum Species 0.000 description 1
- 235000015459 Lycium barbarum Nutrition 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C3/00—Cyanogen; Compounds thereof
- C01C3/08—Simple or complex cyanides of metals
- C01C3/12—Simple or complex iron cyanides
-
- 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
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- 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
-
- 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
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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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
- H01M2004/028—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
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Abstract
The invention belongs to the technical field of novel energy storage batteries, and discloses a coated Prussian bletilla striata and a preparation method and application thereof. The chemical formula of the coated Prussian white is K x Na 2‑x AFe(CN) 6 Is represented by the chemical formula Na 2 AFe(CN) 6 Has a core and a chemical formula of K 2 AFe(CN) 6 Wherein x =0.06-0.6, A is Ni 2+ 、Co 2+ 、Mn 2+ Or Fe 2+ At least one of (1). The preparation method comprises washing Prussian white with potassium salt solution under centrifugal force to make at least part of sodium ions on the surface replaced by potassium ions; the rotational frequency of the centrifugal force is 10-60Hz. The coated prussian white provided by the invention can reduce the water absorption of prussian white and also can greatly improve the rate capability of a sodium ion battery prepared by using the coated prussian white; and the preparation method has simple preparation process and can greatly shorten the preparation time.
Description
Technical Field
The invention belongs to the technical field of novel energy storage batteries, and particularly relates to a coated Prussian bletilla striata and a preparation method and application thereof.
Background
As the price of lithium carbonate increases, the profit of lithium ion batteries is greatly compressed. Compared with the lithium ion anode material, the manufacturing cost of the sodium ion anode material is lower. Sodium is a common element in sodium cathode materials, which significantly reduces the manufacturing cost of the materials and is increasingly favored in the energy storage industry. As one of sodium ion anode materials, the Prussian white has strong water absorption and has great influence on the cycle performance and the rate capability of the battery cell, so that the reduction of the water content and the water absorption of the material is of great significance.
Coating is a common material modification method, and currently, a lot of methods for coating prussian white exist. The conventional coating reaction generally comprises the steps of liquid phase synthesis, filtration, washing, drying and the like to prepare a material to be coated, then putting the material to be coated back into a reaction kettle, adding water for slurrying, adding a coating agent into the kettle for coating reaction, and then performing the second filtration, washing and drying steps to obtain a coating modified product. The whole process flow is complicated, the steps are repeated, the time consumption is overlong, and the loss rate is high. In some coating methods, in order to reduce the working procedures and improve the yield, slurry which is prepared by liquid phase synthesis reaction and contains a substance to be coated is left in a reaction kettle, is kept at a certain temperature and is stirred, and then a coating agent is added for reaction, so that the required coating modified material can be obtained only by one time of filtering, washing and drying. However, this method also has many disadvantages, for example, slurry prepared by the synthesis reaction contains a large amount of salt impurities, which may interfere with the coating reaction, thereby affecting the product performance. If the method is adopted to coat the Prussian white, the purity of the Prussian white is inevitably influenced, and the performance of the sodium-ion battery is influenced.
Therefore, it is highly desirable to provide coated prussian white, which is prepared by a simple process and can greatly shorten the preparation time, and the prepared prussian white material can improve the performance of a sodium ion battery.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a coated prussian rhizoma bletillae and a preparation method and application thereof. The coated prussian white provided by the invention can reduce the water absorption of prussian white and improve the performance of a sodium ion battery; and the preparation process is simple, and the preparation time can be greatly shortened.
The invention provides a coated prussian white in a first aspect.
Specifically, the chemical formula of the coated prussian white is K x Na 2-x AFe(CN) 6 The coated Prussian white has a chemical formula of Na 2 AFe(CN) 6 Has a core and a chemical formula of K 2 AFe(CN) 6 Wherein x =0.06-0.6, A is Ni 2+ 、Co 2+ 、Mn 2+ 、Fe 2+ At least one of (1).
Preferably, in the chemical formula, x =0.06-0.3.
Preferably, the coated prussian white is prepared by washing prussian white with a potassium salt solution under the action of centrifugal force, so that at least a part of sodium ions on the surface of the prussian white are replaced by potassium ions.
The invention provides a preparation method of coated prussian white in a second aspect.
Specifically, the preparation method of the coated prussian white comprises the following steps:
under the action of centrifugal force, washing the Prussian white by using a potassium salt solution to replace at least part of sodium ions on the surface of the Prussian white by potassium ions; then washing and drying to prepare coated Prussian white; the rotational frequency at which the centrifugal force is generated is 10-60Hz.
Preferably, the rotational frequency at which the centrifugal force is generated is 15-50Hz; further preferably, the rotational frequency at which the centrifugal force is generated is 20-40Hz. Experiments find that when the prussian white is washed by using a potassium salt solution, the control of centrifugal force is one of important factors influencing the coating effect. When the rotation frequency is too low during washing, the centrifugal force applied to the potassium salt solution is insufficient, and the prussian white is difficult to soak; when the washing is carried out, the rotating frequency is too high, namely the rotating speed is too high, the centrifugal effect is too strong, the sylvite solution is easily and quickly thrown away from equipment, the contact time with the Prussian white is too short, and a good coating effect cannot be achieved.
It will be appreciated that the equipment for generating the centrifugal force is not limited, and a centrifuge is generally used in the process. The process for washing the prussian white can be finished by adopting the centrifugal machine, and the subsequent water washing process can be carried out, so that the transfer times of materials are reduced, and the preparation process is simplified.
Preferably, the potassium salt in the potassium salt solution is at least one of potassium sulfate, potassium nitrate, potassium chloride or potassium citrate.
Preferably, the concentration of the potassium salt solution is 0.3-3mol/L; further, the concentration of the potassium salt solution is 0.5 to 2mol/L.
Preferably, the amount of material of the potassium salt solution is 20% to 100% of the amount of material of the prussian white. Such as 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, 90%.
Preferably, the washing time is 2 to 15 minutes; more preferably, the washing time is 5 to 10 minutes. The prussian white is washed by adopting a sylvite solution, and the deterioration of the coating layer can be effectively prevented by controlling the washing time. After the potassium salt solution is added into the Prussian white, the reaction can be almost completely carried out within a few minutes, and after the reaction, a good coating effect can be achieved through short-time aging (namely, the washing process comprises the reaction and the aging process). If the washing time is too long, potassium ions originally in the coating layer on the surface of the material can migrate and diffuse into the material under the condition of aqueous solution, so that the coating layer is degraded, and a plurality of holes are formed on the surface of the material.
Preferably, the temperature of the drying is 150 to 180 ℃.
It is understood that the prussian white may be a product purchased directly or a product prepared by a conventional method.
Preferably, the prussian white is prepared by the following method:
under the atmosphere of protective gas, mixing a ferrocyanide solution, a metal salt solution and a complexing agent solution, reacting at 40-95 ℃, then aging the slurry obtained by the reaction for 6-48h, and centrifugally separating to remove a separation liquid to obtain the Prussian white.
Preferably, the concentration of the sodium ferrocyanide solution is 0.3-0.6mol/L.
Preferably, the metal salt in the metal salt solution is one or more of sulfate, nitrate, acetate and chloride of nickel, cobalt, manganese and ferrous iron.
Preferably, the concentration of the metal salt solution is 0.5-2mol/L.
Preferably, the reaction is carried out with a reaction pH of 6.5 to 9.5.
Preferably, the complexing agent is at least one of citric acid, maleic acid, lycium barbarum acid, ethylenediaminetetraacetic acid, sodium citrate, and ammonia.
Preferably, the concentration of the complexing agent solution is 0.5-5mol/L.
More specifically, the preparation method of the coated prussian white comprises the following steps:
(1) Preparing a ferrocyanide solution, a metal salt solution and a complexing agent solution, introducing protective gas into a reaction kettle to prevent oxidation, raising the temperature to 40-95 ℃, adding the sodium ferrocyanide solution, the metal salt solution and the complexing agent solution into the reaction kettle for reaction, controlling the addition amount of the ferrocyanide solution, keeping the pH value of the reaction to be 6.5-9.5, then aging the reacted slurry for 6-48h, and then centrifugally separating to remove a separation solution to obtain the prussian white;
(2) Putting the prussian white into a centrifuge, controlling the rotation frequency of the centrifuge to be 10-60Hz, washing the prussian white by adopting a potassium salt solution to enable potassium ions to partially replace sodium ions on the surface of the prussian white to form a coating layer, then washing the coating layer with water to remove impurities, and drying the coating layer at 150-180 ℃ to obtain the coated prussian white.
The invention provides an application of coated prussian white in a third aspect.
Specifically, the coated Prussian white is applied to preparation of a battery cathode material.
A positive plate comprises the coated Prussian white.
In a fourth aspect, the invention provides a sodium ion battery.
Concretely, a sodium ion battery includes above-mentioned positive plate.
Preferably, the battery cathode material is a sodium-ion battery cathode material.
The technical scheme provided by the invention is that under the action of centrifugal force, prussian white is washed by potassium salt solution, and when the potassium salt solution flows through the prussian white, K of potassium-based prussian white SP The potassium ions in the solution can partially replace sodium ions on the surface of the Prussian white (the actual utilization rate of potassium salt is 10-30%, and finally potassium replaces 3-30% of the amount of sodium in the Prussian white), a coating layer is formed on the surface of the material, and the structure of the inner core of the material is Na 2 AFe(CN) 6 The coating layer structure is K 2 AFe(CN) 6 And A is one or more of nickel, cobalt, manganese and ferrous iron. In addition, a small amount of attachments are also present on the surface of the material, and the attachment is formed by recrystallization after the material is dissolved, and the structure of the attachment is consistent with that of the coating layer. On one hand, the radius of K ions is slightly larger than that of Na ions, so that when the K is used for replacing Na, the material crystal lattice is distorted, and the space and the channel are reduced. The uncoated Prussian white is easy to absorb moisture in the air when being taken out after being dried, so that the water content of the product is higher; the coated Prussian white formed by washing has the advantages that the water molecule channel is reduced due to the distortion of the surface crystal lattice, the water absorption is greatly reduced when the material is dried and taken out, and the water content of the obtained productAnd is significantly reduced. On the other hand, due to the existence of the coating layer, the structural stability of the material in the charging and discharging process can be effectively improved, the side reaction with electrolyte is reduced, the interface stability and the cycle performance are improved, the rate capability of the material is also greatly improved, and the specific capacity under high rate is almost 2 times of that of the uncoated material.
Compared with the prior art, the invention has the following beneficial effects:
(1) The prussian white is washed by potassium salt solution under the action of centrifugal force, and the prussian white is well coated by controlling the rotating frequency and the washing time of the centrifugal force, and the formed kernel is Na 2 AFe(CN) 6 The coating layer is K 2 AFe(CN) 6 Coated prussian white. The coating mode enables the material crystal lattice to be distorted, the space and the channel to be reduced, the water absorption of the Prussian white can be effectively reduced, and the stability of the battery material is improved; meanwhile, the rate capability of the sodium ion battery prepared by using the material can be greatly improved, and particularly, the specific capacity of the battery under high rate (5C) is almost 2 times of that of the battery without the coating material.
(2) The preparation method provided by the invention can also effectively prevent potassium ions in the coating layer from migrating and diffusing to the interior of Prussian white, so that more holes appear on the surface of the material, the degradation risk of the coating layer is reduced, and the stability of the material is improved.
(3) According to the invention, under the action of centrifugal force, the prussian white is washed by the potassium salt solution, the coating process can be completed in a centrifugal machine, namely, in the normal washing step, the procedure of one-step washing by the potassium salt solution is inserted, and the procedure is not required to be completed in a reaction kettle, so that the material transfer times are reduced, the preparation procedure is simplified, the preparation time is shortened, the manpower and material resources are greatly saved, and the production cost is reduced.
Drawings
FIG. 1 is a process flow diagram of the preparation of coated Prussian white of example 1;
fig. 2 is an SEM image of the coated prussian white prepared in example 1;
fig. 3 is an SEM image of prussian white prepared in comparative example 1;
fig. 4 is an SEM image of the coated prussian white prepared in comparative example 2.
Detailed Description
In order to make the technical solutions of the present invention more clearly apparent to those skilled in the art, the following examples are given for illustration. It should be noted that the following examples are not intended to limit the scope of the claimed invention.
The starting materials, reagents or apparatuses used in the following examples are, unless otherwise specified, either commercially available from conventional sources or can be obtained by known methods.
Example 1
A coated Prussian white with chemical formula of K 0.2 Na 1.8 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated prussian white comprises the following steps:
(1) Synthesizing Prussian white: preparing 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing mother liquor in the slurry, and leaving filter cakes in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 20Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the using amount of potassium sulfate is 50% of the molar amount of the prussian white in the centrifuge, calculating the flow of the potassium sulfate solution, ensuring that the time for washing the prussian white filter cakes is 8 minutes, and partially substituting potassium ions for sodium ions on the surface of the prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 10% of the amount of sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium salt solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of the volume of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.2 Na 1.8 MnFe(CN) 6 。
The process flow diagram of the above preparation method is shown in fig. 1.
Example 2
A coated Prussian white with chemical formula of K 0.1 Na 1.9 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated Prussian white comprises the following steps:
(1) Synthesizing prussian white: preparing 0.4mol/L sodium ferrocyanide solution, 2mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 75 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.2, and the reacted slurry is aged for 12 hours. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing mother liquor in the slurry, and leaving filter cakes in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 20Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the using amount of potassium sulfate is 25% of the molar amount of the prussian white in the centrifuge, calculating the flow of the potassium sulfate solution, ensuring that the time for washing the prussian white filter cakes is 6 minutes, and partially substituting potassium ions for sodium ions on the surface of the prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 5% of the sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium sulfate solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of that of the aging slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.1 Na 1.9 MnFe(CN) 6 。
Example 3
A coated Prussian white with chemical formula of K 0.08 Na 1.92 Fe[Fe(CN) 6 ]Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 Fe[Fe(CN) 6 ]The chemical formula of the coating layer is K 2 Fe[Fe(CN) 6 ]。
A preparation method of coated prussian white comprises the following steps:
(1) Synthesizing prussian white: preparing 0.5mol/L sodium ferrocyanide solution, 1.5mol/L ferrous sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 75 ℃, and simultaneously pumping the sodium ferrocyanide solution, the ferrous sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.5 times of that of the ferrous sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.1, and the reacted slurry is aged for 12 hours. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing the mother liquor in the slurry, and leaving the filter cake in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 30Hz, introducing 2mol/L potassium chloride salt solution into the centrifuge to wash filter cakes, wherein the using amount of potassium chloride is 60% of the molar amount of the prussian white in the centrifuge, calculating the flow of the potassium chloride solution, so that the time for washing the prussian white filter cakes is 5 minutes, and potassium ions partially replace sodium ions on the surfaces of the prussian white to form coating layers. The coating utilization of potassium chloride was tested to be about 13% and potassium replaced about 4% of the sodium amount.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium chloride solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.5 times of the volume of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.08 Na 1.92 Fe[Fe(CN) 6 ]。
Example 4
A coated Prussian white with chemical formula of K 0.08 Na 1.92 CoFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 CoFe(CN) 6 The chemical formula of the coating layer is K 2 CoFe(CN) 6 。
A preparation method of coated Prussian white comprises the following steps:
(1) Synthesizing prussian white: preparing 0.4mol/L sodium ferrocyanide solution, 2mol/L cobalt sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 85 ℃, and simultaneously pumping the sodium ferrocyanide solution, the cobalt sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow rate of the sodium citrate solution is 2 times of that of the cobalt sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of the sodium ferrocyanide is controlled, the reaction pH is kept at 8.0, and the reacted material is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing mother liquor in the slurry, and leaving filter cakes in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 30Hz, introducing 2mol/L potassium chloride salt solution into the centrifuge to wash filter cakes, wherein the using amount of potassium chloride is 60% of the molar amount of the Prussian white in the centrifuge, calculating the flow of potassium sulfate solution to ensure that the time for washing the Prussian white filter cakes is 5 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 13% and potassium replaced about 4% of the sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium chloride solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.5 times of the volume of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.08 Na 1.92 CoFe(CN) 6 。
Example 5
A coated Prussian white with chemical formula of K 0.1 Na 1.9 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated prussian white comprises the following steps:
(1) Synthesizing Prussian white: preparing 0.4mol/L sodium ferrocyanide solution, 2mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 75 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.5 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 7.8, and the reacted slurry is aged for 12 hours. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing the mother liquor in the slurry, and leaving the filter cake in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 20Hz, introducing 1mol/L potassium nitrate salt solution into the centrifuge to wash filter cakes, wherein the using amount of potassium nitrate is 50% of the molar amount of the prussian white in the centrifuge, calculating the flow of potassium sulfate solution, ensuring that the time for washing the prussian white filter cakes is 10 minutes, and partially substituting sodium ions on the surfaces of the prussian white by potassium ions to form a coating layer. The potassium nitrate coating utilization rate is about 20% and potassium replaces about 5% of the amount of sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium nitrate solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of the volume of the aging slurry. Drying the filter cake at 170 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.1 Na 1.9 MnFe(CN) 6 。
Example 6
A coated Prussian white with chemical formula of K 0.16 Na 1.84 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated Prussian white comprises the following steps:
(1) Synthesizing prussian white: preparing 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing mother liquor in the slurry, and leaving filter cakes in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 40Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the usage amount of potassium sulfate is 50% of the mole amount of the Prussian white in the centrifuge, calculating the flow of the potassium sulfate solution to ensure that the time for washing the Prussian white filter cakes is 5 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. Tests show that the coating utilization rate of potassium sulfate is about 20%, and potassium replaces about 8% of sodium.
(3) Washing and drying: washing bag for washing potassium salt solution in centrifugal machineAnd the covered filter cake is continuously washed by pure water to remove impurities in the filter cake, and the volume of the washing water is 0.4 time of that of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.16 Na 1.84 MnFe(CN) 6 。
Example 7
A coated Prussian white with chemical formula of K 0.12 Na 1.88 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated prussian white comprises the following steps:
(1) Synthesizing Prussian white: preparing 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing mother liquor in the slurry, and leaving filter cakes in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 10Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the usage amount of potassium sulfate is 50% of the mole amount of the Prussian white in the centrifuge, calculating the flow of the potassium sulfate solution to ensure that the time for washing the Prussian white filter cakes is 8 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 6% of the sodium.
(3) Washing and drying: washing the filter cake coated with potassium salt solution in centrifuge with pure water to remove impurities in the filter cakeImpurity, the volume of washing water is 0.4 times of the volume of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.12 Na 1.88 MnFe(CN) 6 。
Example 8
A coated Prussian white with chemical formula of K 0.12 Na 1.88 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated prussian white comprises the following steps:
(1) Synthesizing prussian white: preparing 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18 hours. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing the mother liquor in the slurry, and leaving the filter cake in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 60Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the usage amount of potassium sulfate is 50% of the mole amount of the Prussian white in the centrifuge, calculating the flow of the potassium sulfate solution to ensure that the time for washing the Prussian white filter cakes is 8 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 6% of the sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium salt solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of the volume of the aged slurry. Then the filter is filteredDrying the cake at 180 deg.C to obtain coated Prussian white product with chemical formula of K 0.12 Na 1.88 MnFe(CN) 6 。
Example 9
A coated Prussian white with chemical formula of K 0.14 Na 1.86 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated Prussian white comprises the following steps:
(1) Synthesizing Prussian white: 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution are prepared. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing the mother liquor in the slurry, and leaving the filter cake in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 20Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the usage amount of potassium sulfate is 50% of the mole amount of the Prussian white in the centrifuge, calculating the flow of the potassium sulfate solution to ensure that the time for washing the Prussian white filter cakes is 3 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 7% of the amount of sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium salt solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of the volume of the aged slurry. Drying the filter cake at 180 deg.C to obtain coated Prussian white product, and dissolvingHas a chemical formula of K 0.14 Na 1.86 MnFe(CN) 6 。
Example 10
A coated Prussian white with chemical formula of K 0.24 Na 1.76 MnFe(CN) 6 Comprises an inner core layer and a coating layer, wherein the chemical formula of the inner core is Na 2 MnFe(CN) 6 The chemical formula of the coating layer is K 2 MnFe(CN) 6 。
A preparation method of coated Prussian white comprises the following steps:
(1) Synthesizing prussian white: 0.5mol/L sodium ferrocyanide solution, 1.6mol/L manganese sulfate solution and 2mol/L sodium citrate solution are prepared. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 65 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow of the sodium citrate solution is 1.2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.5, and the reacted slurry is aged for 18h. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, removing the mother liquor in the slurry, and leaving the filter cake in the centrifugal machine.
(2) Coating prussian white: keeping the centrifuge rotating at 20Hz, introducing 0.5mol/L potassium sulfate solution into the centrifuge to wash filter cakes, wherein the usage amount of potassium sulfate is 50% of the mole amount of the Prussian white in the centrifuge, calculating the flow of the potassium sulfate solution, so that the time for washing the Prussian white filter cakes is 15 minutes, and potassium ions partially replace sodium ions on the surface of the Prussian white to form a coating layer. The coating utilization of potassium sulfate was tested to be about 20% and potassium replaced about 12% of the amount of sodium.
(3) Washing and drying: and (3) continuously washing the filter cake coated by the potassium salt solution in the centrifuge with pure water to remove impurities in the filter cake, wherein the volume of washing water is 0.4 times of the volume of the aged slurry. Drying the filter cake at 180 ℃ to obtain a coated Prussian white product with a chemical formula of K 0.24 Na 1.76 MnFe(CN) 6 。
Comparative example 1
Comparative document 1 is a method of preparing an uncoated Prussian white product of the formula Na without washing the filter cake with a potassium salt solution in the step (2) and the remaining preparation steps are the same as in example 1 2 MnFe(CN) 6 。
Comparative example 2
The comparison document 2 is a method for preparing coated prussian white by adopting a traditional coating method in a reaction kettle, and specifically comprises the following steps:
(1) Synthesizing prussian white: preparing 0.4mol/L sodium ferrocyanide solution, 2mol/L manganese sulfate solution and 2mol/L sodium citrate solution. Adding a proper amount of pure water into the reaction kettle, reaching the position of a stirring paddle, starting stirring, introducing nitrogen into the reaction kettle to prevent oxidation, raising the temperature to 75 ℃, and simultaneously pumping the sodium ferrocyanide solution, the manganese sulfate solution and the sodium citrate solution into the reaction kettle by using a metering pump, wherein the flow rate of the sodium citrate solution is 2 times of that of the manganese sulfate solution. The solution is subjected to precipitation reaction in a reaction kettle, the flow of sodium ferrocyanide is controlled, the reaction pH is kept at 8.2, and the reacted slurry is aged for 12 hours. And (3) leading the prussian white slurry in the aging tank to a centrifugal machine for filtering, and removing the mother liquor in the slurry to obtain prussian white filter cake.
(2) Coating prussian white: putting the prussian white filter cake into a reaction kettle, adding water for slurrying, starting stirring, and adding 0.5mol/L potassium sulfate solution into the kettle, wherein the use amount of the potassium sulfate is 10% of the molar amount of the prussian white in the reaction kettle. The coating is carried out in a reaction kettle, and the potassium sulfate almost completely reacts. Aging for 30min, filtering and washing the slurry in the reaction kettle in a centrifuge to obtain a filter cake, and drying the filter cake at 180 deg.C to obtain a coated Prussian white product with chemical formula K 0.2 Na 1.8 MnFe(CN) 6 。
Product effectiveness testing
The prussian white products prepared in examples 1-10 and comparative examples 1-2 were tested.
The specific test method and test results are as follows:
(1) The coated prussian white prepared in example 1 and comparative example 2, and the uncoated prussian white product prepared in comparative example 1 were analyzed by scanning electron microscopy.
Fig. 2 is an SEM image of the coated prussian white prepared in example 1, and a small amount of coating was observed on the surface of the material when the coating process was performed in a centrifuge. Fig. 3 is an SEM image of uncoated prussian white prepared in comparative example 1, the material was uncoated, the surface was smooth, and there was no attachment; fig. 4 is an SEM image of the coated prussian white prepared in comparative example 2, the coating process was performed in a reaction kettle, the aging time was 30min, a large number of holes appeared on the surface of the material, the morphology was seriously deteriorated, which was caused by etching potassium ions into the material, and also a small amount of attachments formed by recrystallization after dissolution existed on the surface of the material.
(2) The particle diameters of the prussian white products prepared in examples 1 to 10 and comparative examples 1 to 2 were measured using a dry particle sizer.
(3) The prussian white products prepared in examples 1-10 and comparative examples 1-2 were tested for moisture content (wt%) by drying at 150 ℃ for 1h using an automatic moisture meter.
(4) Prussian white products prepared in examples 1-10 and comparative examples 1-2 are used for preparing a positive plate, metal sodium is used for preparing a negative electrode, and NaPF 6 The Ethylene Carbonate (EC)/diethyl carbonate (DEC) solution is used as electrolyte and assembled into a button type half cell in a glove box. And then testing the charge-discharge specific capacity of the battery at 0.1C and 5C multiplying power within the voltage range of 2.0-4.0V.
The test results are shown in table 1.
TABLE 1 test results
As can be seen from table 1, in example 1, the morphology of the material did not change much compared to comparative example 1, but the moisture content of the coated material (the coated prussian white prepared in example 1) was greatly reduced, the 0.1C specific discharge capacity was almost unchanged, and the 5C specific discharge capacity was significantly improved. Compared with the comparative example 1, the comparative example 2 has the advantages that a large number of holes are formed on the surface of the coated Prussian white obtained by the conventional method, the moisture content is not reduced and increased, the discharge specific capacities of 0.1C and 5C are greatly reduced, and the product performance is seriously deteriorated. The coated prussian white prepared in the examples 2 to 6 has similar effects to those of the example 1, the moisture content is reduced, and the 5C specific discharge capacity is remarkably improved compared with that of the comparative example 1. Compared with the coated Prussian white prepared in the comparative example 1, the 5C specific discharge capacity of the coated Prussian white prepared in the examples 7 to 10 is also remarkably improved; the discharge specific capacity of 0.1C was comparable to that of examples 1 to 6, but the water content and the discharge specific capacity of 5C were slightly inferior to those of examples 1 to 6. Therefore, the coated prussian white prepared by a washing method under the action of centrifugal force can reduce the water absorption and moisture content of prussian white, and the charge-discharge specific capacity of a sodium ion battery prepared by the coated prussian white at high rate is remarkably improved; the rotational frequency and the washing time for generating the centrifugal force also affect the stability of the sodium battery, especially the specific discharge capacity under high rate (5C).
Claims (10)
1. The coated Prussian white is characterized in that the chemical formula of the coated Prussian white is K x Na 2-x AFe(CN) 6 The coated Prussian white has a chemical formula of Na 2 AFe(CN) 6 Has a core and a chemical formula of K 2 AFe(CN) 6 Wherein x =0.06-0.6, A is Ni 2+ 、Co 2+ 、Mn 2+ 、Fe 2+ At least one of (1).
2. The coated prussian white as claimed in claim 1, wherein in the formula, x =0.06-0.3.
3. The method for preparing the coated prussian white as claimed in claim 1 or 2, which comprises the steps of:
under the action of centrifugal force, washing the Prussian white by using a potassium salt solution to replace at least part of sodium ions on the surface of the Prussian white by potassium ions; then washing and drying to prepare coated Prussian white; the rotational frequency at which the centrifugal force is generated is 10-60Hz.
4. The production method according to claim 3, wherein the rotational frequency at which the centrifugal force is generated is 15 to 50Hz; preferably, the rotational frequency at which the centrifugal force is generated is 20-40Hz.
5. The method according to claim 3, wherein the potassium salt in the potassium salt solution is at least one of potassium sulfate, potassium nitrate, potassium chloride and potassium citrate.
6. The method according to claim 3, wherein the concentration of the potassium salt solution is 0.3 to 3mol/L.
7. The production method according to any one of claims 3 and 5 to 6, wherein the amount of the substance of the potassium salt solution is 20% to 100% of the amount of the substance of prussian white.
8. The method according to claim 3, wherein the washing time is 2 to 15 minutes; preferably, the washing time is 5 to 10 minutes.
9. A positive electrode sheet comprising the coated prussian white of claim 1 or 2.
10. A sodium ion battery comprising the positive electrode sheet according to claim 9.
Priority Applications (4)
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| CN202210914516.1A CN115196653B (en) | 2022-07-29 | 2022-07-29 | Coated Prussian white and preparation method and application thereof |
| PCT/CN2022/119466 WO2024021255A1 (en) | 2022-07-29 | 2022-09-16 | Coated prussian white, method for preparing same, and use thereof |
| GB2311864.9A GB2627835A (en) | 2022-07-29 | 2022-09-16 | Coated Prussian white, method for preparing same, and use thereof |
| FR2308156A FR3138425A1 (en) | 2022-07-29 | 2023-07-28 | COATED PRUSSIAN WHITE (PW) AND PREPARATION METHOD AND USE THEREOF |
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| CN202210914516.1A CN115196653B (en) | 2022-07-29 | 2022-07-29 | Coated Prussian white and preparation method and application thereof |
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| CN116425175A (en) * | 2023-04-23 | 2023-07-14 | 广东凯金新能源科技股份有限公司 | Prussian white positive electrode material preparation method, positive electrode material and secondary battery |
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| JP2020092086A (en) * | 2018-11-26 | 2020-06-11 | 学校法人東京理科大学 | Positive electrode material for potassium ion secondary battery and method of producing the same |
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| CN114188502A (en) * | 2021-11-30 | 2022-03-15 | 湖南钠方新能源科技有限责任公司 | Prussian white composite material and preparation method and application thereof |
| CN114497472A (en) * | 2021-12-08 | 2022-05-13 | 电子科技大学长三角研究院(湖州) | Prussian blue positive electrode material with multilayer structure and preparation method and application thereof |
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| US9123966B2 (en) * | 2011-06-22 | 2015-09-01 | Alveo Energy, Inc. | Stabilization of battery electrodes using prussian blue analogue coatings |
| JP2015079685A (en) * | 2013-10-18 | 2015-04-23 | 株式会社豊田中央研究所 | Aqueous solution-based secondary battery |
| CN106549155A (en) * | 2016-10-20 | 2017-03-29 | 河南师范大学 | A kind of potassium sodium ferromanganese base prussian blue electrode material and its preparation method and application |
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2022
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| JP2020092086A (en) * | 2018-11-26 | 2020-06-11 | 学校法人東京理科大学 | Positive electrode material for potassium ion secondary battery and method of producing the same |
| CN112645354A (en) * | 2020-12-21 | 2021-04-13 | 电子科技大学 | Surface-modified sodium-manganese-iron-based Prussian blue material and preparation method and application thereof |
| CN114188502A (en) * | 2021-11-30 | 2022-03-15 | 湖南钠方新能源科技有限责任公司 | Prussian white composite material and preparation method and application thereof |
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