CN114572956A - Nano-scale olivine type sodium iron phosphate, preparation method and application - Google Patents
Nano-scale olivine type sodium iron phosphate, preparation method and application Download PDFInfo
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- CN114572956A CN114572956A CN202210180561.9A CN202210180561A CN114572956A CN 114572956 A CN114572956 A CN 114572956A CN 202210180561 A CN202210180561 A CN 202210180561A CN 114572956 A CN114572956 A CN 114572956A
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- iron phosphate
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- sodium
- olivine
- lithium iron
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- 239000010450 olivine Substances 0.000 title claims abstract description 20
- 229910052609 olivine Inorganic materials 0.000 title claims abstract description 20
- AWRQDLAZGAQUNZ-UHFFFAOYSA-K sodium;iron(2+);phosphate Chemical compound [Na+].[Fe+2].[O-]P([O-])([O-])=O AWRQDLAZGAQUNZ-UHFFFAOYSA-K 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 12
- WBJZTOZJJYAKHQ-UHFFFAOYSA-K iron(3+) phosphate Chemical compound [Fe+3].[O-]P([O-])([O-])=O WBJZTOZJJYAKHQ-UHFFFAOYSA-K 0.000 claims abstract description 27
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims abstract description 26
- 229910001415 sodium ion Inorganic materials 0.000 claims abstract description 26
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 22
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000003756 stirring Methods 0.000 claims abstract description 19
- 229910000398 iron phosphate Inorganic materials 0.000 claims abstract description 18
- 229910052786 argon Inorganic materials 0.000 claims abstract description 12
- 239000000463 material Substances 0.000 claims abstract description 12
- 239000003638 chemical reducing agent Substances 0.000 claims abstract description 11
- 239000003960 organic solvent Substances 0.000 claims abstract description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 11
- 238000005303 weighing Methods 0.000 claims abstract description 10
- 239000007800 oxidant agent Substances 0.000 claims abstract description 8
- 230000001590 oxidative effect Effects 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 7
- 238000001035 drying Methods 0.000 claims abstract description 6
- 238000010521 absorption reaction Methods 0.000 claims abstract description 4
- 238000005054 agglomeration Methods 0.000 claims abstract description 4
- 230000002776 aggregation Effects 0.000 claims abstract description 4
- 238000009837 dry grinding Methods 0.000 claims abstract description 3
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Chemical group [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 claims description 27
- 239000007774 positive electrode material Substances 0.000 claims description 14
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 12
- 235000009518 sodium iodide Nutrition 0.000 claims description 9
- -1 nitrate tetrafluoroborate Chemical group 0.000 claims description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000002105 nanoparticle Substances 0.000 claims description 4
- 238000001291 vacuum drying Methods 0.000 claims description 4
- 229910000399 iron(III) phosphate Inorganic materials 0.000 abstract description 21
- 239000011734 sodium Substances 0.000 abstract description 21
- 230000008569 process Effects 0.000 abstract description 11
- 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 abstract description 10
- 229910052708 sodium Inorganic materials 0.000 abstract description 10
- 239000010405 anode material Substances 0.000 abstract description 9
- 239000005955 Ferric phosphate Substances 0.000 abstract description 7
- 230000008859 change Effects 0.000 abstract description 7
- 229940032958 ferric phosphate Drugs 0.000 abstract description 7
- 238000007599 discharging Methods 0.000 abstract description 3
- 230000007246 mechanism Effects 0.000 abstract description 3
- 238000011056 performance test Methods 0.000 description 13
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000000498 ball milling Methods 0.000 description 7
- 229910021312 NaFePO4 Inorganic materials 0.000 description 6
- 239000010406 cathode material Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229920000447 polyanionic polymer Polymers 0.000 description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- 238000004146 energy storage Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 238000005342 ion exchange Methods 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 229910052493 LiFePO4 Inorganic materials 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000007858 starting material Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 239000011149 active material Substances 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000003487 electrochemical reaction Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000002086 nanomaterial Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000006245 Carbon black Super-P Substances 0.000 description 1
- 229910004069 NO2BF4 Inorganic materials 0.000 description 1
- 229910019398 NaPF6 Inorganic materials 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 229910003002 lithium salt Inorganic materials 0.000 description 1
- 159000000002 lithium salts Chemical class 0.000 description 1
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 238000007709 nanocrystallization Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000005373 porous glass Substances 0.000 description 1
- 229960003351 prussian blue Drugs 0.000 description 1
- 239000013225 prussian blue Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 229910001575 sodium mineral Inorganic materials 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000012798 spherical particle Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—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
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- 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
-
- 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
-
- 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
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
Abstract
The invention belongs to the technical field of sodium ion battery materials, and particularly relates to nanoscale olivine type sodium iron phosphate and a preparation method and application thereof. Weighing lithium iron phosphate, and placing the lithium iron phosphate in a planetary ball mill for dry milling to obtain nanoscale lithium iron phosphate; weighing nanoscale lithium iron phosphate in an argon glove box, placing the nanoscale lithium iron phosphate in an organic solvent, adding an oxidant, stirring, centrifuging, and drying in vacuum to generate iron phosphate; grinding the iron phosphate in an argon glove box to prevent water absorption and avoid agglomeration, weighing the iron phosphate, placing the iron phosphate in an organic solvent, adding a reducing agent, stirring, centrifuging, and drying in vacuum to obtain the sodium ferric phosphate, namely the nanoscale olivine type sodium ferric phosphate. The nano-scale sodium ferric phosphate changes the phase change mechanism in the charging and discharging process, is visually expressed as the smearing of a charging platform, and improves the cycle stability. In addition, the elements of the anode material are rich and widely distributed in the earth crust at present, and the anode material is low in cost and environment-friendly.
Description
Technical Field
The invention belongs to the technical field of sodium ion battery materials, and particularly relates to nanoscale olivine type sodium iron phosphate and a preparation method and application thereof.
Background
The energy crisis and environmental pollution are the common problems facing all countries in the world. Improving the resource ratio of renewable energy sources such as solar energy, wind energy, tidal energy, geothermal energy and the like is considered as an optimal solution to energy and environmental problems. Although the total amount of the energy is large, the energy is only intermittent under the influence of weather and regions and is difficult to be directly utilized. Therefore, there is an urgent need for a low-cost, environmentally friendly energy storage technology that integrates these intermittent energies into a continuous, stable and controllable grid.
Among various energy storage devices, secondary batteries represented by lithium ion batteries have been applied to various portable devices and electric vehicles due to their high efficiency of energy conversion and storage devices, portability, environmental friendliness, high energy density, and power density. However, due to the widespread use of lithium ion batteries, the demand for lithium ore resources is expanding, resulting in increasing prices of lithium and related lithium salts, and thus lithium ion batteries are not an ideal choice for low cost energy storage technologies. The sodium ion battery has sufficient sodium mineral resources and wide distribution, and simultaneously, the sodium and the lithium have similar physicochemical properties, so that the compounds of the sodium ion battery have great similarity in research methods and application and are considered as the best choice for a large-scale energy storage system.
Like lithium ion batteries, positive electrode materials of sodium ion batteries are difficult points and hot points in the research of sodium ion batteries. The positive electrode material of the sodium ion battery is mainly divided into a layered transition metal oxide NaxTMO2(TM is transition metal element), polyanion compound, Prussian blue compound, etc. The polyanion compound has the characteristics of higher ionic conductivity and stable structure, has better cycle performance and rate capability, and has attracted extensive attention of researchers.
LiFePO4With its excellent thermal safety, high reversibility andhigher operating voltage (3.45vs Li)+/Li), exhibit high competitiveness and have begun to be applied to commercial automobiles. In sodium ion batteries, NaFePO4Because it has the same LiFePO4The similar olivine structure has better electrochemical performance. However, NaFePO4The thermodynamically stable phase of (a) is a structure of the nano-phosphosiderite. Therefore, the method of solid phase, hydrothermal and the like is easy to prepare the structure of the nano ferro-phosphorus ore. In the structure of Napatite, Na+There are no diffusion channels, and the structure shows electrochemical inertness. Therefore, how to synthesize olivine-type NaFePO having electrochemical properties was studied4Is a difficult point which is needed to be solved urgently.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a nano-scale olivine polyanion cathode material NaxFePO4A preparation method thereof and a sodium ion battery, which solve or partially solve the problems in the prior art.
In a first aspect, the invention provides a preparation method of a nanoscale olivine type positive electrode material, which comprises the following steps:
(1) weighing lithium iron phosphate, and placing the lithium iron phosphate in a planetary ball mill for dry milling to obtain nanoscale lithium iron phosphate;
(2) in an argon glove box with the water oxygen value lower than 0.01ppm, weighing nanoscale lithium iron phosphate, placing the nanoscale lithium iron phosphate into an organic solvent, adding an oxidant according to a certain stoichiometric ratio, and stirring, centrifuging and vacuum-drying to generate iron phosphate;
(3) grinding the iron phosphate in an argon glove box with the water oxygen value lower than 0.01ppm to prevent water absorption and avoid agglomeration, weighing the iron phosphate, placing the iron phosphate in an organic solvent, adding a reducing agent according to a certain stoichiometric ratio, stirring, centrifuging, and drying in vacuum to obtain the sodium iron phosphate, namely the nanoscale olivine type sodium iron phosphate.
Preferably, in the step (1), lithium iron phosphate is weighed according to the ball material mass ratio of 10:1, and is pre-milled for 60min at the speed of 300rpm/min and then is ball-milled for 60min at the speed of 300-900 rpm/min.
Preferably, in step (2) and step (3), the organic solvent is at least one of acetonitrile and ethanol.
Preferably, in the step (2), the oxidant is nitrate tetrafluoroborate, and the molar ratio of the nitrate tetrafluoroborate to the lithium iron phosphate is 1.5: 1.
preferably, in the step (2), the stirring time is 24 hours, and the stirring temperature is normal temperature.
Preferably, in the step (3), the reducing agent is sodium iodide, and the molar ratio of the sodium iodide to the iron phosphate is 2: 1.
Preferably, in the step (3), the stirring time is 48-56 hours, and the stirring temperature is 30-60 ℃.
In a second aspect, the present invention provides a nano-sized olivine type NaxFePO4The method aims to reduce the limit of the reverse defect on the specific capacity of the sodium iron phosphate, promote the formation of a sodium ion diffusion channel by using an organic solvent and improve the specific capacity of the cathode material to a certain extent.
Further, through the change of the size, the structural change of the material in the electrochemical cycle process is stabilized, and olivine type Na is inhibitedxFePO4The phase change process of the anode material in the charging process further improves the cycle performance of the anode material.
In a third aspect, the invention provides a nano-sized olivine polyanion cathode material NaxFePO4The application of the olivine polyanion cathode material NaxFePO4The positive electrode material can be applied to a sodium ion battery, and comprises the following steps:
mixing and grinding the positive active material, conductive carbon black (Super P) and a binder (PVDF) according to a mass ratio of 8:1: 1-6: 3:1, preferably a mass ratio of 7:2:1 for 25min, coating the active material on an aluminum foil, drying in vacuum, rolling and slicing to prepare a positive plate; the metal sodium is used as a negative electrode; using glass fiber filter paper of a GF/D battery diaphragm as a diaphragm; matching sodium hexafluorophosphate electrolyte, assembling into a sodium ion battery in a glove box filled with argon, standing for 10h, and then carrying out corresponding electrochemical performance test; the performance test voltage window is 1.5-4V; the performance test current density is selected from 0.1C and 1C.
The invention provides a method for preparing nano-scale sodium ferric phosphate by mechanical ball milling and ion exchange. The nano-scale sodium iron phosphate changes the phase change mechanism in the charging and discharging process, is visually represented as smearing of a charging platform, and improves the cycle stability. In addition, the elements of the anode material are rich and widely distributed in the current earth crust, have low cost, belong to environment-friendly elements and have good environmental protection value. Compared with the prior art, the method has the following beneficial effects:
(1) the prepared anode material successfully synthesizes an olivine structure by an ion exchange method, avoids the generation of a phosphosiderite structure, simultaneously utilizes solvent synthesis to reduce the concentration of inversion defects to a certain extent, and more sodium ions participate in the charging and discharging process, thereby being beneficial to further improving the actual capacity.
(2) The invention stabilizes the structural change of the material in the electrochemical cycle process by nanocrystallization and changes olivine NaxFePO4In the phase change process of the positive electrode material in the charging process, the positive electrode material tends to carry out ion exchange in a solid solution mode, so that the cycle performance of the positive electrode material is improved, and higher cycle stability is obtained.
(3) The invention provides a preparation method of a nano-sized olivine type anode material by a mechanical ball milling and ion exchange method, and the anode material has the characteristics of high cycle performance, good stability, low cost and environmental friendliness, and is not restricted by lithium resources.
Drawings
FIG. 1 shows NaFePO as a positive electrode material prepared in example 14X-ray diffraction pattern (XRD).
Fig. 2 is a Scanning Electron Microscope (SEM) photograph of the cathode material prepared in example 1.
Fig. 3 is a typical charge and discharge curve for the first 3 cycles of the battery prepared in example 1.
Fig. 4 is a graph of the cycle performance of the first 50 cycles of the battery prepared in example 1.
FIG. 5 is a graph showing the electrochemical comparison of example 3 with example 2 (first turn).
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the present invention will be further described in detail with reference to specific embodiments. The following description is intended only to illustrate the invention and not to limit its content, and all reagents and materials are commercially available in the art.
Example 1
(I) preparing a positive electrode material NaFePO4。
(1) Weighing lithium iron phosphate according to a ball-to-material ratio of 10:1, placing the lithium iron phosphate into a ball milling tank, carrying out dry ball milling in a planetary ball mill, wherein the rotating speed of the ball mill is 300rpm/min, the total ball milling time is 2 hours, grinding a sample for 3 minutes after the ball milling is finished, and placing the sample in an argon glove box with the water oxygen value lower than 0.01 ppm.
(2) Placing nanoscale lithium iron phosphate into acetonitrile in an argon glove box with the water oxygen value lower than 0.01ppm, adding an oxidant namely tetrafluoroborate nitrate according to the proportion of 1.5:1, continuously stirring for 24 hours at normal temperature until the reaction is complete, centrifuging for 4 to 5 times to separate the iron phosphate, and drying in vacuum at the temperature of 60 ℃ to obtain the iron phosphate.
(3) Grinding iron phosphate in an argon glove box with the water oxygen value lower than 0.01ppm to prevent water absorption and avoid agglomeration so as to facilitate subsequent reaction, then placing the mixture in acetonitrile, adding a reducing agent sodium iodide in a ratio of 2:1, regulating the stirring temperature to 60 ℃, preferably adjusting the temperature rise rate to 5 ℃/min, continuously stirring for 48 hours so as to facilitate reaction, centrifuging for 4 to 5 times to separate sodium iron phosphate, and performing vacuum drying at 60 ℃ to obtain the sodium iron phosphate.
In the step (2) and the step (3), the total weight concentration of the raw materials in the stirring process is not more than 2.5g/50 ml; in the embodiment of the application, 50% of the oxidant and the reducing agent need to be added in excess;
specifically, in the step (2) of the application, the lithium iron phosphate is placed in an organic solvent, an oxidant of nitronium tetrafluoroborate is added, and the chemical reaction involved in generating the iron phosphate after the reaction is as follows:
LiFePO4+NO2BF4→FePO4+NO2+LiBF4
in the step (3), lithium iron phosphate is placed in an organic solvent, a reducing agent sodium iodide is added, and the chemical reaction involved in generating sodium iron phosphate after the reaction is as follows:
FePO4+3/2NaI→NaFePO4+1/2NaI3
and (II) assembling the sodium-ion battery.
And (2) taking the anode material prepared in the step (I) as an anode active substance, taking conductive carbon black Super P as a conductive agent, taking polyvinylidene fluoride (PVDF) as a binder, adding the active material, the Super P and the PVDF into a mortar according to the mass ratio of preferably 7:2:1, and grinding for 25 min. Coating the aluminum foil serving as a current collector into a thin sheet, and preparing the thin sheet into a positive plate through a slicing machine after the thin sheet is completely dried in a vacuum drying oven; the negative electrode is metallic sodium, and the electrolyte is NaPF6(EC: DEC ═ 1:1 Vol%) solution, using a porous glass fiber membrane (GF/D) as a separator, was assembled into a button cell in an argon glove box with a water oxygen value of less than 0.01 ppm.
And (III) testing the electrochemical performance of the sodium-ion battery.
Electrochemical performance tests were performed on the assembled cells using a blue cell test system. The voltage window is set at 1.5-4V, and the electrochemical performance test is carried out by selecting constant rates of current density of 0.1C, 0.5C and 1C according to the specific capacity obtained by theoretical calculation and the mass of the corresponding positive pole piece active substance. Typical charge and discharge curves are shown in fig. 3.
Example 2
Changing the size of the lithium iron phosphate, ball milling at 300rpm/min for 60min and 600rpm/min for 60min in the step (1) of the example 2, adjusting the stirring temperature to 50 ℃ in the step (3) of the example 2, and preparing NaFePO by the same method as that of the example 14。
The remaining assembled sodium ion cells and electrochemical performance tests were performed as in example 1.
Example 3
The preparation method of the lithium iron phosphate is the same as that of the step (1) in the embodiment 1 except that the step (1) in the embodiment 3 is omitted without changing the size of the lithium iron phosphatePrepare NaFePO4。
The remaining assembled sodium ion cells and electrochemical performance tests were performed as in example 1.
Example 4
Changing the sodium ratio in the substance, wherein the molar ratio of the ferric phosphate to the reducing agent sodium iodide in the step (3) is 1:1 in the same manner as in example 1 except that Na was preparedxFePO4。
The remaining assembled sodium ion cells and electrochemical performance tests were performed as in example 1.
Example 5
Changing the sodium ratio in the substance, wherein the molar ratio of the ferric phosphate to the reducing agent sodium iodide in the step (3) is 1:1 in the same manner as in example 2 except that Na was preparedxFePO4。
The remaining assembled sodium ion cells and electrochemical performance tests were performed as in example 1.
Example 6
Changing the sodium ratio in the substance, wherein the molar ratio of the ferric phosphate to the reducing agent sodium iodide in the step (3) is 1:1 in the same manner as in example 3 except that Na was preparedxFePO4。
The remaining assembled sodium ion cells and electrochemical performance tests were performed as in example 1.
The positive electrode material of the sodium-ion battery prepared in the above example was assembled into a battery, and then subjected to the following electrochemical performance test.
1. The test voltage was between 1.5 and 4.0V, and the current density was 0.1C (1C: 154mA/g) for charge and discharge performance, and the results are shown in the following table.
| Item | Specific charging capacity (mAh/g) | Specific discharge capacity (mAh/g) | Coulombic efficiency (%) |
| Example 1 | 122 | 118.4 | 97.04 |
| Example 2 | 100.6 | 97.9 | 97.31 |
| Example 3 | 120 | 115.9 | 96.58 |
| Example 4 | 94.5 | 93.8 | 99.25 |
| Example 5 | 68.3 | 65.5 | 95.90 |
| Example 6 | 108.3 | 107.7 | 99.44 |
2. The charge-discharge cycle stability of the material is tested, the test voltage is 1.5-4.0V, the current density is 0.1C, the capacity can still be maintained at 88% after 100 cycles, and the cycle performance chart is shown in figure 4.
3. The electrochemical curves of the materials with different sizes are changed, the test voltage is between 1.5 and 4.0V, the electrochemical performance test is carried out under the condition that the current rate is 0.1C, and the test result is shown in figure 5.
FIG. 1 is an X-ray diffraction pattern of the cathode material prepared in example 1 of the present invention, and it can be seen from the pattern that it conforms to the characteristic peak of olivine-type sodium iron phosphate, indicating that the sample has a Pnma space group structure. FIG. 2 is a scanning electron micrograph of the material from which it can be seen that the spherical particles are less than 200nm in diameter.
Electrochemical performance tests were performed on the sodium ion battery prepared as described above, and the results are shown in fig. 3. As can be seen from figure 3, the material has voltage platforms at 2.8V and 3.1V, which represent NaFePO4An electrochemical platform;
fig. 5 is a charge curve of nanoscale versus starting material, the nanoscale material differing primarily in smearing of the voltage plateau relative to the starting material. The voltage plateaus of the starting material at 2.8V and 3.1V indicate NaFePO during the electrochemical reaction4→Na2/3FePO4，Na2/3FePO4→Na0FePO4The nano-scale material has no obvious voltage platform, and the whole body shows an inclined voltage curve, which indicates that the electrochemical reaction process tends to be carried out in a solid solution mechanism.
The specific capacity of the nanoscale olivine type positive electrode material is kept to be 78% of the initial capacity, and compared with the research of other related sodium ion batteries, the nanoscale olivine type positive electrode material has extremely excellent cycle performance.
Claims (6)
1. A preparation method of nanoscale olivine type sodium iron phosphate is characterized by comprising the following specific steps:
(1) weighing lithium iron phosphate, and placing the lithium iron phosphate in a planetary ball mill for dry milling to obtain nanoscale lithium iron phosphate;
(2) weighing nanoscale lithium iron phosphate in an argon glove box, placing the nanoscale lithium iron phosphate in an organic solvent, adding an oxidant according to a certain stoichiometric ratio, and stirring, centrifuging and vacuum-drying to generate iron phosphate;
(3) grinding the iron phosphate in an argon glove box to prevent water absorption and avoid agglomeration, weighing the iron phosphate, placing the iron phosphate in an organic solvent, adding a reducing agent according to a certain stoichiometric ratio, stirring, centrifuging, and drying in vacuum to obtain the sodium iron phosphate, namely the nanoscale olivine type sodium iron phosphate.
2. The preparation method of the nanoscale olivine-type sodium iron phosphate as claimed in claim 1, wherein in the step (1), the lithium iron phosphate is weighed according to the ball material mass ratio of 10:1, and is pre-milled at the speed of 300rpm/min for 60min and then ball-milled at the speed of 300-900 rpm/min for 60 min.
3. The method for preparing nano-sized olivine-type sodium iron phosphate according to claim 1, wherein in the steps (2) and (3), the organic solvent is at least one of acetonitrile and ethanol; the water oxygen value in the argon glove box is lower than 0.01 ppm.
4. The method for preparing nanoscale olivine-type sodium iron phosphate according to claim 1, wherein in the step (2), the oxidant is nitrate tetrafluoroborate, and the molar ratio of the nitrate tetrafluoroborate to the lithium iron phosphate is 1.5: 1; the stirring time is 24h, and the stirring temperature is normal temperature.
5. The method for preparing nano-scale olivine-type sodium iron phosphate according to claim 1, wherein in the step (3), the reducing agent is sodium iodide, and the molar ratio of sodium iodide to iron phosphate is 2: 1; the stirring time is 48-56 h, and the stirring temperature is 30-60 ℃.
6. Use of the nanoscale olivine-type sodium iron phosphate prepared by any of the preparation methods of claims 1 to 5, for the preparation of sodium-ion batteries as a positive electrode material for sodium-ion batteries.
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| CN115520848A (en) * | 2022-09-28 | 2022-12-27 | 广东邦普循环科技有限公司 | Lithium iron phosphate positive electrode material and preparation method and application thereof |
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| CN105047913A (en) * | 2015-05-22 | 2015-11-11 | 武汉大学 | Method of preparing olivine-type sodium ferric phosphate through electrochemical method |
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| CN105047913A (en) * | 2015-05-22 | 2015-11-11 | 武汉大学 | Method of preparing olivine-type sodium ferric phosphate through electrochemical method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115275207A (en) * | 2022-09-27 | 2022-11-01 | 天津蓝天太阳科技有限公司 | Biomass carbon-coated sodium iron phosphate composite material and preparation method and application thereof |
| CN115275207B (en) * | 2022-09-27 | 2022-12-09 | 天津蓝天太阳科技有限公司 | Biomass carbon-coated sodium iron phosphate composite material and preparation method and application thereof |
| CN115520848A (en) * | 2022-09-28 | 2022-12-27 | 广东邦普循环科技有限公司 | Lithium iron phosphate positive electrode material and preparation method and application thereof |
| CN115520848B (en) * | 2022-09-28 | 2024-03-08 | 广东邦普循环科技有限公司 | Lithium iron phosphate positive electrode material, and preparation method and application thereof |
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