CN117303450A - Preparation method and application of battery-grade sodium iron sulfate - Google Patents
Preparation method and application of battery-grade sodium iron sulfate Download PDFInfo
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- CN117303450A CN117303450A CN202311241015.2A CN202311241015A CN117303450A CN 117303450 A CN117303450 A CN 117303450A CN 202311241015 A CN202311241015 A CN 202311241015A CN 117303450 A CN117303450 A CN 117303450A
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- atmosphere
- iron sulfate
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- YPPMLCHGJUMYPZ-UHFFFAOYSA-L sodium;iron(2+);sulfate Chemical compound [Na+].[Fe+2].[O-]S([O-])(=O)=O YPPMLCHGJUMYPZ-UHFFFAOYSA-L 0.000 title claims abstract description 52
- 238000002360 preparation method Methods 0.000 title abstract description 20
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims abstract description 96
- 239000012298 atmosphere Substances 0.000 claims abstract description 39
- 239000011261 inert gas Substances 0.000 claims abstract description 28
- 239000011259 mixed solution Substances 0.000 claims abstract description 25
- 239000002243 precursor Substances 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 22
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims abstract description 21
- 239000011790 ferrous sulphate Substances 0.000 claims abstract description 21
- 235000003891 ferrous sulphate Nutrition 0.000 claims abstract description 21
- 229910000359 iron(II) sulfate Inorganic materials 0.000 claims abstract description 21
- 229910052938 sodium sulfate Inorganic materials 0.000 claims abstract description 21
- 235000011152 sodium sulphate Nutrition 0.000 claims abstract description 21
- 238000005245 sintering Methods 0.000 claims abstract description 19
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000010438 heat treatment Methods 0.000 claims abstract description 13
- 229910001415 sodium ion Inorganic materials 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 12
- 235000015165 citric acid Nutrition 0.000 claims abstract description 10
- 238000003756 stirring Methods 0.000 claims abstract description 10
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims abstract 7
- 239000011734 sodium Substances 0.000 claims description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 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 claims description 13
- 229910052708 sodium Inorganic materials 0.000 claims description 13
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 7
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 239000001257 hydrogen Substances 0.000 claims description 7
- 229910052739 hydrogen Inorganic materials 0.000 claims description 7
- 229910052757 nitrogen Inorganic materials 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 6
- 230000000996 additive effect Effects 0.000 claims description 6
- 239000012300 argon atmosphere Substances 0.000 claims description 6
- -1 preferably Substances 0.000 claims description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 3
- 229910017052 cobalt Inorganic materials 0.000 claims description 3
- 239000010941 cobalt Substances 0.000 claims description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 3
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 5
- 230000008569 process Effects 0.000 abstract description 12
- 239000002245 particle Substances 0.000 abstract description 5
- 238000009776 industrial production Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 18
- SURQXAFEQWPFPV-UHFFFAOYSA-L iron(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Fe+2].[O-]S([O-])(=O)=O SURQXAFEQWPFPV-UHFFFAOYSA-L 0.000 description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 239000007774 positive electrode material Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 238000000227 grinding Methods 0.000 description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-L Phosphate ion(2-) Chemical compound OP([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-L 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 125000004436 sodium atom Chemical group 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000000498 ball milling Methods 0.000 description 3
- 239000003575 carbonaceous material Substances 0.000 description 3
- 239000008139 complexing agent Substances 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 3
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000004146 energy storage Methods 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000004080 punching Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 229910019398 NaPF6 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 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
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 229920000447 polyanionic polymer Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910000314 transition metal oxide Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
- C01G49/009—Compounds containing, besides iron, two or more other elements, with the exception of oxygen or hydrogen
-
- 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
- H01M4/581—Chalcogenides or intercalation compounds thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/624—Electric conductive fillers
- H01M4/625—Carbon or graphite
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Crystallography & Structural Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a preparation method of battery-grade sodium iron sulfate, which comprises the following steps: preparing a mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion, keeping the mixed solution in an inert gas atmosphere or a reducing atmosphere, heating and stirring the mixed solution to form sol, and drying and crushing the sol to obtain a precursor; and sintering and crushing the precursor to obtain the battery-grade sodium iron sulfate. The battery grade ferric sodium sulfate prepared by the preparation method provided by the invention has high purity, complete and uniform particles and good electrochemical performance. Meanwhile, the preparation method has simple process flow and is suitable for large-scale industrial production. The invention also comprises a sodium ion battery using the battery-grade ferric sodium sulfate as an anode.
Description
Technical Field
The invention relates to the technical field of batteries, in particular to a preparation method and application of battery-grade sodium iron sulfate.
Background
As a representative secondary battery with the highest comprehensive performance, commercialization of a lithium ion battery can be traced back to the 90 th century, and research on the lithium ion battery has been conducted for many years to have a mature battery technology route. However, lithium ion batteries are difficult to support in the current growing energy storage market, limited by the abundance of lithium element crust. The working principle of the sodium ion battery is similar to that of a lithium ion battery, the sodium salt reserves are rich, the exploitation is simple, and the method has more advantages in the large-scale application direction in the subsequent energy storage field.
The sodium ion battery mainly comprises a positive electrode, a negative electrode, electrolyte, a diaphragm and accessory parts. The positive and negative electrode materials are key to influence the performance of the sodium ion battery system, and the positive electrode materials are particularly prominent. The positive electrode materials of sodium ion batteries are classified into three main categories, namely transition metal oxides, prussian white/blue and polyanions. The positive electrode material of the polyanionic sodium ion battery has the advantages of stable structure and small volume change during charge and discharge. Among the positive electrode materials of the polyanionic sodium ion battery, the iron-based sodium battery has the advantages of lowest cost and no toxicity, wherein the sodium iron sulfate is a positive electrode material with higher performance, and has the advantages of low cost, environmental friendliness, high theoretical capacity and excellent cycle performance.
At present, aiming at the preparation of sodium iron sulfate, a preparation process of sintering and solidifying after ball milling and mixing is mainly adopted, the integrity of material particles can be damaged in the process of multiple ball milling, the particle size of the particles is difficult to regulate and control, uncontrollable factors can exist in the material performance, and in the process of ball milling, grinding aid ethanol is required to be added, so that potential safety hazards exist, and the large-scale industrialization is not facilitated.
Disclosure of Invention
In view of the above, the present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a preparation method and application of battery-grade sodium iron sulfate. The preparation method provided by the invention can be used for preparing the battery-grade sodium iron sulfate with complete and uniform particles, and further can be used as a battery anode material to improve the utilization rate of the battery material. Meanwhile, the preparation method has simple process flow and is suitable for large-scale industrial production.
To this end, in a first aspect, an embodiment of the present invention provides a method for preparing battery-grade sodium iron sulfate, where the method includes:
s10, preparing a mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion, keeping the mixed solution in an inert gas atmosphere or a reducing atmosphere, heating and stirring the mixed solution to form sol, and drying and crushing the sol to obtain a precursor;
and S20, sintering and crushing the precursor to obtain the battery-grade sodium iron sulfate.
Preferably, the mixed solution of ferrous sulfate, sodium sulfate and citric acid is prepared according to a certain proportion, and specifically comprises the following steps: and preparing a mixed solution of ferrous sulfate, sodium hydroxide and citric acid according to a certain proportion.
Preferably, the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon.
Preferably, the mixed solution of ferrous sulfate, sodium sulfate and citric acid is prepared according to a certain proportion, and specifically comprises the following steps: according to a certain proportion, preparing a mixed solution of ferrous sulfate, an additive, sodium sulfate and citric acid, wherein the additive comprises sulfate of at least one of manganese, nickel and cobalt.
Preferably, the molar ratio of the sodium element in the sodium sulfate to the iron element in the ferrous sulfate is 1.0.ltoreq.n (Na): n (Fe). Ltoreq.3.0; and/or the number of the groups of groups,
the carbon element in the citric acid accounts for 1-10% of the theoretical product sodium iron sulfate by weight; and/or the number of the groups of groups,
the heating temperature is 80-95 ℃; and/or the number of the groups of groups,
the sol is dried for 6-10 h at 70-90 ℃.
Preferably, the sintering of the precursor is controlled under certain temperature conditions; preferably, the temperature is raised to 150-250 ℃ at 3-5 ℃ per minute, kept for 2-6 hours, and then raised to 300-400 ℃ at 1-3 ℃ per minute, and kept for 12-30 hours.
Preferably, the sintering control of the precursor is performed under inert gas atmosphere or reducing atmosphere conditions.
Preferably, the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon.
In a second aspect, the embodiment of the invention also provides a battery-grade sodium iron sulfate, which is prepared by the preparation method provided by the first aspect.
In a third aspect, an embodiment of the present invention further provides a sodium ion battery, where the sodium ion battery includes the positive electrode prepared from the battery-level sodium iron sulfate provided in the second aspect and the negative electrode of the sodium sheet.
The preparation method of the battery-grade sodium ferric sulfate provided by the embodiment of the invention has the advantages of simple process flow, high efficiency, no need of high-end equipment, no need of adding expensive reagents, low-cost and easily-obtained raw materials, and no involvement of toxic and harmful raw materials; the preparation method adopts a wet system for mixing, so that the uniformity of the materials in the coating and mixing process can be further ensured; citric acid is introduced, the citric acid can be used as a complexing agent of solution gel and also can be used as a carbon source of carbon coating, carbon after the citric acid is decomposed reacts in situ to form carbon coating on the surface of sodium ferric sulfate, the conductivity of the material is enhanced, and the electrochemical performance is improved.
Drawings
FIG. 1 is a flow chart of a method for preparing battery grade sodium iron sulfate according to an embodiment of the present invention;
FIG. 2 is an XRD pattern of battery grade sodium iron sulfate prepared in example 1 of the present invention;
FIG. 3 is an XRD pattern of battery grade sodium iron sulfate prepared in example 2 of the present invention;
fig. 4 is an XRD pattern of battery grade sodium iron sulfate prepared in comparative example 3 of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
The following disclosure provides many different embodiments, or examples, for implementing different structures of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the applicability of other processes and/or the use of other materials.
Referring to fig. 1, the present invention aims to provide a method for preparing battery grade sodium iron sulfate, wherein the chemical formula of the sodium iron sulfate positive electrode material is as follows: na (Na) x Fe(SO4) y Wherein y= (x+2)/2; x is more than or equal to 1.0 and less than or equal to 3.0. The preparation method comprises the following steps:
s10, preparing a mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion, keeping the mixed solution in an inert gas atmosphere or a reducing atmosphere, heating and stirring the mixed solution to form sol, and drying and crushing the sol to obtain a precursor;
and S20, sintering and crushing the precursor to obtain the battery-grade sodium iron sulfate.
Specifically, in the step S10, ferrous sulfate, a sodium source and citric acid are weighed and dissolved in deionized water according to a certain proportion, then the mixed solution is kept to form sol under the condition of inert gas atmosphere or reducing atmosphere and heating and stirring, and the precursor is obtained after the sol is dried and crushed.
Further, the mixed solution of ferrous sulfate, sodium sulfate and citric acid is prepared according to a certain proportion, and specifically comprises the following steps: and preparing a mixed solution of ferrous sulfate, sodium hydroxide and citric acid according to a certain proportion. I.e. during the gelling of said step S10, a small amount of sodium hydroxide is further added. Wherein, the addition of sodium hydroxide solves the problem that the carboxyl of citric acid is relative to Fe 2+ The problem of lower complexing coefficient can further improve the Fe 2+ Is used as a complexing agent.
Specifically, the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon. That is, during the heating and stirring process of the step S10, inert gas atmosphere such as nitrogen or argon or reducing atmosphere containing a small amount of hydrogen is introduced, which is more beneficial to Fe 2+ Is protected from oxidation.
Preferably, the mixed solution of ferrous sulfate, sodium sulfate and citric acid is prepared according to a certain proportion, and specifically comprises the following steps: according to a certain proportion, preparing a mixed solution of ferrous sulfate, an additive, sodium sulfate and citric acid, wherein the additive comprises sulfate of at least one of manganese, nickel and cobalt. In the embodiment, metal ions such as Mn, ni, co and the like are doped to replace Fe ions at the B site, so that the electronic conductivity of the material is improved, and the charge-discharge specific capacity of the material is further improved.
Further, in the step S10, the molar ratio of the sodium element in the sodium sulfate to the iron element in the ferrous sulfate is 1.0.ltoreq.n (Na): n (Fe). Ltoreq.3.0. The carbon element in the citric acid accounts for 1-10% wt of the theoretical product sodium iron sulfate. The heating temperature is 80-95 ℃. The sol is dried for 6-10 h at 70-90 ℃. Specifically, ferrous sulfate, a sodium source and citric acid are mixed according to sodium atoms and iron atoms X:1 (x is more than or equal to 1.0 and less than or equal to 3.0), adding citric acid according to the weight percent of carbon element of 1-10%, heating in water bath under stirring condition, wherein the water bath temperature is 80-95 ℃ until no obvious moisture is evaporated, transferring into a blast drying oven, drying for 6-10 hours at 70-90 ℃, and crushing and grinding to prepare the precursor.
Further, the step S20 includes:
sintering: sintering the precursor in a box furnace under a certain temperature condition to obtain a block material, and controlling the temperature and the atmosphere uniformity in the sintering process.
Crushing: and crushing the material obtained by sintering by a roller machine to obtain powder, namely the carbon-coated sodium iron sulfate anode material.
Wherein, the sintering of the precursor is controlled under a certain temperature condition; preferably, the temperature is raised to 150-250 ℃ at 3-5 ℃ per minute, kept for 2-6 hours, and then raised to 300-400 ℃ at 1-3 ℃ per minute, and kept for 12-30 hours. Specifically, the first stage temperature platform, namely 150-250 ℃, is used for removing moisture in the material; the first stage temperature platform, 300-400 deg.c, is the material sintering reaction temperature.
Wherein the sintering of the precursor is controlled under the condition of inert gas atmosphere or reducing atmosphere. Further, the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon. Under the condition of inert gas atmosphere or reducing atmosphere, avoiding Fe 2+ Oxidation to Fe 3+ 。
In a second aspect, the embodiment of the invention also provides a battery-grade sodium iron sulfate, which is prepared by the preparation method provided by the first aspect.
In a third aspect, an embodiment of the present invention further provides a sodium ion battery, where the sodium ion battery includes the positive electrode prepared from the battery-level sodium iron sulfate provided in the second aspect and the negative electrode of the sodium sheet.
The following describes the specific procedures and effects of the preparation method of battery grade sodium iron sulfate according to the present invention in further detail with reference to some specific examples, but is not limited to the scope of the present invention.
Example 1
The embodiment prepares the battery-grade sodium iron sulfate and the battery-grade anhydrous ferric hydrogen phosphate, and specifically comprises the following steps:
1. 2.78kg of ferrous sulfate heptahydrate, 1.42kg of sodium sulfate and 0.56kg of citric acid are weighed; wherein Na is 2 SO 4 FeSO 4 The molar ratio of the sodium atoms to the iron atoms is 2:1, and the carbon-based material accounts for 5 percent by weight
2. The raw materials are dissolved by deionized water and then heated in water bath under the stirring condition, the heating temperature is 80-95 ℃, and the gel is formed and then transferred into a blast drying oven for drying.
3. And crushing and grinding the dried substance to obtain a precursor.
4. Sintering the precursor at about 350 ℃, maintaining the temperature for 24 hours in nitrogen atmosphere, and obtaining the battery-grade sodium iron sulfate.
The XRD is used for analyzing the prepared battery grade sodium iron sulfate, and the result is shown in figure 2, and compared with a standard card, the synthesized battery grade sodium iron sulfate has the advantages of single phase, high purity, no impurity peak and good crystallinity.
Example 2
The embodiment prepares the battery-grade sodium iron sulfate and the battery-grade anhydrous ferric hydrogen phosphate, and specifically comprises the following steps:
1. 2.78kg of ferrous sulfate heptahydrate, 1.42kg of sodium sulfate and 0.896kg of citric acid are weighed; wherein Na is 2 SO 4 FeSO 4 The molar ratio of the sodium atoms to the iron atoms is 2:1, and the carbon-based material accounts for 8 percent by weight
2. The raw materials are dissolved by deionized water and then heated in water bath under the stirring condition, the heating temperature is 80-95 ℃, and the gel is formed and then transferred into a blast drying oven for drying.
3. And crushing and grinding the dried substance to obtain a precursor.
4. Sintering the precursor at about 350 ℃, maintaining the temperature for 24 hours in nitrogen atmosphere, and obtaining the battery-grade sodium iron sulfate.
The XRD is used for analyzing the prepared battery grade sodium iron sulfate, and the result is shown in figure 3, and compared with a standard card, the synthesized battery grade sodium iron sulfate has the advantages of single phase, high purity, no impurity peak and good crystallinity.
Example 3
The embodiment prepares the battery-grade sodium iron sulfate and the battery-grade anhydrous ferric hydrogen phosphate, and specifically comprises the following steps:
the preparation method of the carbon-coated sodium iron sulfate positive electrode material comprises the following steps:
1. 2.78kg of ferrous sulfate heptahydrate, 1.42kg of sodium sulfate and 0.56kg of citric acid are weighed; wherein Na is 2 SO 4 FeSO 4 The molar ratio of the sodium atoms to the iron atoms is 2:1, and the carbon-based material accounts for 5 percent by weight
2. The raw materials are dissolved by deionized water and then heated in water bath under the stirring condition, the heating temperature is 80-95 ℃, and the gel is formed and then transferred into a blast drying oven for drying.
3. And crushing and grinding the dried substance to obtain a precursor.
4. Sintering the precursor at about 375 ℃, maintaining the temperature for 24 hours in a nitrogen atmosphere, and obtaining the battery-grade anhydrous ferric hydrogen phosphate.
The XRD is used for analyzing the prepared battery grade sodium iron sulfate, and the result is shown in figure 4, and compared with a standard card, the synthesized battery grade sodium iron sulfate has the advantages of single phase, high purity, no impurity peak and good crystallinity.
Further, after adding an appropriate amount of NMP to the battery grade sodium iron sulfate, acetylene black and PVDF prepared in examples 1-3 in a mass ratio of 90:5:5, mixing and homogenizing, a black paste was coated on an aluminum foil using a 150 μm four-side preparer, and then the film was dried in a vacuum oven at 110℃for 6 hours. And punching the dried electrode film into a wafer with the same radius by using a sheet punching machine to obtain the positive electrode sheet. The metal sodium is used as a negative electrode plate, the diaphragm is a glass fiber membrane, the electrolyte is NaPF6/EC+DEC+DMC (EC: DEC: DMC=1:1:1 volume ratio), and the button cell is assembled in a glove box. The results of testing the first charge-discharge capacity, the discharge rate and the like are shown in table 1, and the battery prepared based on the above embodiment has good electrochemical performance and can meet the working requirements of the sodium ion button battery.
TABLE 1 button discharge capacity
The preparation method of the battery-grade sodium iron sulfate provided by the embodiment of the invention has the advantages of simple process flow, high efficiency, no need of high-end equipment, no need of adding expensive and practical materials, low-cost and easily-obtained raw materials, and no involvement of toxic and harmful raw materials; the preparation method adopts a wet system for mixing, so that the uniformity of the materials in the coating and mixing process can be further ensured; citric acid is introduced, the citric acid can be used as a complexing agent of solution gel and also can be used as a carbon source of carbon coating, carbon after the citric acid is decomposed reacts in situ to form carbon coating on the surface of sodium ferric sulfate, the conductivity of the material is enhanced, and the electrochemical performance is improved.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A method for preparing battery-grade sodium iron sulfate, which is characterized by comprising the following steps:
s10, preparing a mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion, keeping the mixed solution in an inert gas atmosphere or a reducing atmosphere, heating and stirring the mixed solution to form sol, and drying and crushing the sol to obtain a precursor;
and S20, sintering and crushing the precursor to obtain the battery-grade sodium iron sulfate.
2. The method for preparing battery-grade sodium iron sulfate according to claim 1, wherein the preparing the mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion comprises the following steps: and preparing a mixed solution of ferrous sulfate, sodium hydroxide and citric acid according to a certain proportion.
3. The method for producing battery grade sodium iron sulfate according to claim 1, wherein the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon.
4. The method for preparing battery-grade sodium iron sulfate according to claim 1, wherein the preparing the mixed solution of ferrous sulfate, sodium sulfate and citric acid according to a certain proportion comprises the following steps: according to a certain proportion, preparing a mixed solution of ferrous sulfate, an additive, sodium sulfate and citric acid, wherein the additive comprises sulfate of at least one of manganese, nickel and cobalt.
5. The method for producing battery-grade sodium iron sulfate according to claim 1, wherein a molar ratio of sodium element in the sodium sulfate to iron element in the ferrous sulfate is 1.0.ltoreq.n (Na): n (Fe). Ltoreq.3.0; and/or the number of the groups of groups,
the carbon element in the citric acid accounts for 1-10% of the theoretical product sodium iron sulfate by weight; and/or the number of the groups of groups,
the heating temperature is 80-95 ℃; and/or the number of the groups of groups,
the sol is dried for 6-10 h at 70-90 ℃.
6. The method for preparing battery grade sodium iron sulfate according to claim 1, wherein the sintering of the precursor is controlled under a certain temperature condition; preferably, the temperature is raised to 150-250 ℃ at 3-5 ℃ per minute, kept for 2-6 hours, and then raised to 300-400 ℃ at 1-3 ℃ per minute, and kept for 12-30 hours.
7. The method for producing battery grade sodium iron sulfate according to claim 1, wherein the sintering control of the precursor is performed under an inert gas atmosphere or a reducing atmosphere.
8. The method for producing battery grade sodium iron sulfate according to claim 1, wherein the inert gas atmosphere is a nitrogen atmosphere or an argon atmosphere; alternatively, the reducing atmosphere is a mixed atmosphere of 5% hydrogen and 95% inert gas, preferably, the inert gas is nitrogen or argon.
9. A battery grade sodium iron sulfate, characterized in that it is produced according to the production method of any one of claims 1-8.
10. A sodium ion battery comprising a positive electrode prepared from battery grade sodium iron sulfate according to claim 8 and a negative sodium sheet electrode.
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