CN116960281A - Composite polyanion type sodium ferrous sulfate positive electrode material, preparation method thereof and sodium ion battery containing positive electrode material - Google Patents
Composite polyanion type sodium ferrous sulfate positive electrode material, preparation method thereof and sodium ion battery containing positive electrode material Download PDFInfo
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- CN116960281A CN116960281A CN202210419001.4A CN202210419001A CN116960281A CN 116960281 A CN116960281 A CN 116960281A CN 202210419001 A CN202210419001 A CN 202210419001A CN 116960281 A CN116960281 A CN 116960281A
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 149
- 239000011734 sodium Substances 0.000 title claims abstract description 75
- 235000003891 ferrous sulphate Nutrition 0.000 title claims abstract description 45
- 239000011790 ferrous sulphate Substances 0.000 title claims abstract description 45
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 title claims abstract description 40
- 229910000359 iron(II) sulfate Inorganic materials 0.000 title claims abstract description 40
- 229910052708 sodium Inorganic materials 0.000 title claims abstract description 36
- 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 title claims abstract description 32
- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 26
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 239000002131 composite material Substances 0.000 title claims abstract description 21
- 229920000447 polyanionic polymer Polymers 0.000 title claims abstract description 14
- 238000001694 spray drying Methods 0.000 claims abstract description 31
- 238000002156 mixing Methods 0.000 claims abstract description 24
- 239000007790 solid phase Substances 0.000 claims abstract description 19
- 238000000197 pyrolysis Methods 0.000 claims abstract description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 49
- 229910052799 carbon Inorganic materials 0.000 claims description 45
- 239000011159 matrix material Substances 0.000 claims description 35
- 239000007787 solid Substances 0.000 claims description 31
- 239000000843 powder Substances 0.000 claims description 28
- 238000000498 ball milling Methods 0.000 claims description 27
- 239000002243 precursor Substances 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 20
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 18
- 239000011259 mixed solution Substances 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- 150000003839 salts Chemical class 0.000 claims description 10
- 238000009210 therapy by ultrasound Methods 0.000 claims description 10
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 9
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 9
- 235000011152 sodium sulphate Nutrition 0.000 claims description 9
- 235000010323 ascorbic acid Nutrition 0.000 claims description 8
- 229960005070 ascorbic acid Drugs 0.000 claims description 8
- 239000011668 ascorbic acid Substances 0.000 claims description 8
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 claims description 7
- 239000012298 atmosphere Substances 0.000 claims description 7
- 239000003963 antioxidant agent Substances 0.000 claims description 6
- 230000003078 antioxidant effect Effects 0.000 claims description 6
- 235000006708 antioxidants Nutrition 0.000 claims description 6
- 239000011149 active material Substances 0.000 claims description 5
- CIWBSHSKHKDKBQ-DUZGATOHSA-N D-isoascorbic acid Chemical compound OC[C@@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-DUZGATOHSA-N 0.000 claims description 2
- 235000010350 erythorbic acid Nutrition 0.000 claims description 2
- 229940026239 isoascorbic acid Drugs 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 abstract description 13
- 230000008878 coupling Effects 0.000 abstract description 5
- 238000010168 coupling process Methods 0.000 abstract description 5
- 238000005859 coupling reaction Methods 0.000 abstract description 5
- 230000000052 comparative effect Effects 0.000 description 80
- 239000002048 multi walled nanotube Substances 0.000 description 21
- 238000012360 testing method Methods 0.000 description 17
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 16
- 239000000463 material Substances 0.000 description 16
- 239000010406 cathode material Substances 0.000 description 15
- 239000000243 solution Substances 0.000 description 14
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- 230000014759 maintenance of location Effects 0.000 description 11
- 238000001878 scanning electron micrograph Methods 0.000 description 11
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- 238000010438 heat treatment Methods 0.000 description 8
- 239000012299 nitrogen atmosphere Substances 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 230000001351 cycling effect Effects 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 239000011833 salt mixture Substances 0.000 description 6
- 238000005245 sintering Methods 0.000 description 6
- 230000018044 dehydration Effects 0.000 description 5
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- 239000012535 impurity Substances 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 239000010405 anode material Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
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- 238000011160 research Methods 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- 150000003624 transition metals Chemical class 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black 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
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000002041 carbon nanotube Substances 0.000 description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- DCYOBGZUOMKFPA-UHFFFAOYSA-N iron(2+);iron(3+);octadecacyanide Chemical class [Fe+2].[Fe+2].[Fe+2].[Fe+3].[Fe+3].[Fe+3].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCYOBGZUOMKFPA-UHFFFAOYSA-N 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 229910021653 sulphate ion Inorganic materials 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 1
- 229910004563 Na2Fe2 (SO4)3 Inorganic materials 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
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- 230000000295 complement effect Effects 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000003411 electrode reaction Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000004318 erythorbic acid Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- GDPKWKCLDUOTMP-UHFFFAOYSA-B iron(3+);dihydroxide;pentasulfate Chemical compound [OH-].[OH-].[Fe+3].[Fe+3].[Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GDPKWKCLDUOTMP-UHFFFAOYSA-B 0.000 description 1
- 239000003273 ketjen black Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
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- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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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
- 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
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—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
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- 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
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- Crystallography & Structural Chemistry (AREA)
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Abstract
The application provides a composite polyanion sodium ion battery sodium ferrous sulfate positive electrode material, a preparation method thereof and a sodium ion battery containing the positive electrode material, and belongs to the field of sodium ion battery positive electrode materials. The preparation method of the application is a preparation method of coupling spray drying with solid phase mixing and low-temperature pyrolysis reaction processes. The application also provides the composite polyanionic sodium ferrous sulfate positive electrode material prepared by the preparation method. The preparation method disclosed by the application is simple to operate, easy to control and environment-friendly, and the prepared composite polyanionic sodium ferrous sulfate positive electrode material has excellent electrochemical comprehensive performance and can be used for sodium ion batteries.
Description
Technical Field
The application relates to the field of sodium ion battery positive electrode materials, in particular to a composite polyanion type ferrous sodium sulfate positive electrode material, a preparation method thereof and a sodium ion battery containing the positive electrode material.
Background
Energy and environment are the basis for survival and development of human society. Although renewable clean energy systems such as: wind energy, tidal energy, geothermal energy, solar energy and the like relieve two major problems of energy shortage and environmental pollution to be solved in the global scope to a certain extent, but the clean energy exhibits necessary intermittent characteristics due to factors such as weather, geographic positions, climate conditions and the like, and is not beneficial to efficient operation of a power grid. The combination of distributed clean energy stations and large-scale power storage and conversion systems is one of the main directions of the development of the future energy field. The chargeable and dischargeable battery has very wide application prospect due to the advantages of adjustable storage capacity, convenience in movement, high system modularization integration level and the like, and meets the requirements of low cost, high efficiency, large scale, long service life and the like which are required by the energy storage technology at the present stage.
Since the 90 s of the 20 th century, sony corporation has realized commercialization of lithium ion batteries (Lithium ions batteries, LIBs), which have been successfully applied to the fields of portable electronic devices, electric vehicles, energy storage grids, etc., through technological updates and device perfection for many years. However, the global lithium resource is low (the reserve of 0.0065wt% in the crust of the earth) and is difficult to support the increasing market demand, and meanwhile, the long-term large-scale development and application of the lithium ion battery in the fields of energy storage and conversion are limited by major potential safety hazards such as thermal runaway, combustion and the like. Under the background, the method develops Na which is similar to the working principle, the preparation process and the engineering mass production flow of the lithium ion battery and has obvious resource, cost and safety advantages + The sodium ion battery (Sodium ions batteries) which is a carrier is complementary to the lithium ion battery, and even completely replaces the lithium ion battery is a necessary way of large-scale energy storage technology.
Due toMore->The large ionic radius results in very slow transmission dynamics in the surface interface and bulk phase of the electrode material and is accompanied by the phenomena of remarkable volume effect, serious electrode structure damage and the like, which severely restricts the development and commercialization progress of the high-performance sodium ion battery. Thus, studyThe positive electrode material for determining the energy density and the power density of the whole sodium ion battery system is one of main research directions for promoting the large-scale application of sodium ion batteries. The positive electrode material system of interest to date mainly comprises: transition metal layered oxide, prussian blue analogues, polyanion compounds and the like, wherein the transition metal layered oxide is poor in air stability, low in working voltage platform, and accompanied with obvious problems of phase change, complex phase change and the like in the electrode reaction process; prussian blue analogues have open three-dimensional Na + The channel has better structural stability and rate capability, but the crystal structure of the channel has crystal water which is difficult to remove, so that the circulating efficiency is low and the problem of dissolution of transition metal is easy to occur; polyanionic positive electrode material, in particular sodium ferrous sulphate positive electrode material of the aluudite crystal structure, having the highest charge-discharge voltage plateau reported nowadays (3.8 v vs. na + Na), the open three-dimensional frame has the characteristics of high thermal stability, good multiplying power performance, excellent cycle performance, safety, no toxicity, low cost and the like, so that the material has potential market value and application significance in the technical fields of energy storage and miniature electric vehicles.
In 2014, barpanda et al (Nature Communications,2014,5 (1): 4358.) reported Na for the first time 2 Fe 2 (SO 4 ) 3 The sulfate positive electrode material has reversible Na deintercalation + The new field of research on polyanion sulfate anode materials is opened. Since then, many are based on [ SO ] 4 2- ]The positive electrode material with strong induction effect is intensively studied and reported, and research work is focused on the control of raw material Na by pertinence 2 SO 4 And FeSO 4 Optimizing the bulk purity of the sodium ferrous sulfate positive electrode material and the electron conductivity of the carbon matrix doped lifting material. Such as: oyama team (CHEMELECTROCHEM, 2015,2 (7): 1019-1023) by controlling Na 2 SO 4 -FeSO 4 The proportion of the two phases shows that the impurity phases in the prepared sodium ferrous sulfate positive electrode material (comprising Fe 2 O 3 、Na 6 Fe(SO 4 ) 4 、α-FeSO 4 、β-FeSO 4 Etc.) and the content are different. DFT theoretical calculation and Mosburg spectrum analysis are combined to prove that the impurity phase in the sodium ferrous sulfate positive electrode material mainly originates from a small amount of FeSO which does not participate in reaction 4 The positive electrode material obtained in the non-stoichiometric ratio has the highest bulk purity, i.e. the formation of impurity phases during synthesis can be greatly reduced when the sodium salt is slightly excessive (Journal of Materials Chemistry A,2019,7 (21): 13197-13204.). In addition, research and development teams such as Yao (Journal of Energy Chemistry,2020, 50:387-394), wang (Journal of Materials Chemistry A,2018,6 (10): 4354-4364), cao (Journal of Energy Chemistry,2021, 54:564-570), meng (Journal of Materials Chemistry A,2016,4 (5): 1624-1631) all achieve the effect of remarkably improving the circulation, multiplying power and stability of the sodium ferrous sulfate cathode material by introducing different conductive matrixes into the material system.
However, currently strong electronegativity [ SO 4 2- ]Most of the preparation of the sodium ferrous sulfate-based anode material adopts a low-temperature solid-phase ball milling process, and then sintering is carried out at low temperature in an inert atmosphere. FeSO is needed to be carried out before solid-phase ball milling 4 ·nH 2 Dehydrating O raw material at high temperature (about 300 ℃) for a long time (10-12 h) under vacuum or anaerobic atmosphere to prepare anhydrous FeSO 4 However, after the crystallization water is removed, a moist environment is created, resulting in Fe 2+ Is extremely easy to be oxidized into Fe 3+ So that the prepared ferrous sodium sulfate positive electrode material has low bulk purity and Na is removed + Weak ability. Therefore, a new preparation process flow is urgently needed to improve the bulk phase purity and the electrical conductivity of the sodium ferrous sulfate positive electrode material, improve the reversible charge-discharge specific capacity, the multiplying power performance, the cycling stability and other comprehensive electrochemical properties, and accelerate the development of sodium ion batteries.
Disclosure of Invention
In order to solve the technical problems, the application provides a composite polyanion sodium ferrous sulfate positive electrode material, a preparation method thereof and a sodium ion battery containing the positive electrode material, and the preparation method is simple to operate, easy to control and environment-friendly. The composite polyanion sodium ferrous sulfate positive electrode material takes two sulfates and a carbon matrix as raw materials, and is prepared by a spray drying coupling solid phase mixing method, namely: firstly, a powdery bi-component metal salt mixture with atomic level uniformly mixed is obtained by means of spray drying, then the bi-component metal salt mixture powder obtained by spray drying is fully mixed with a carbon matrix by solid phase mixing treatment, interaction among three components is enhanced, and finally, a composite polyanionic sodium ferrous sulfate positive electrode material with excellent electrochemical comprehensive performance is obtained by a pyrolysis reaction process, and the bi-component metal salt mixture powder is suitable for sodium ion batteries.
The technical scheme of the application is as follows:
a preparation method of a composite polyanionic sodium ferrous sulfate positive electrode material, in particular to a preparation method of coupling spray drying with solid phase mixing and low-temperature pyrolysis reaction processes, which comprises the following steps:
s1: uniformly dissolving sodium sulfate and ferrous sulfate in water, adding an antioxidant, and performing ultrasonic treatment to obtain a mixed solution;
s2: carrying out spray drying treatment on the mixed solution obtained in the step S1 to obtain solid powder;
s3: the solid powder obtained in the step S2 is subjected to solid phase mixing treatment with a carbon matrix material to obtain a positive electrode material precursor;
s4: and (3) carrying out thermal pyrolysis reaction on the positive electrode material precursor obtained in the step (S3) under the anaerobic condition to obtain the composite polyanion sodium ferrous sulfate positive electrode material.
According to an embodiment of the application, in step S1, the ferrous sulphate is selected from ferrous sulphate or a crystalline hydrate of ferrous sulphate. Preferably, the crystalline hydrate of ferrous sulfate is FeSO 4 ·nH 2 O, wherein n is selected from 1-7, e.g. crystalline hydrate of ferrous sulphate is FeSO 4 ·7H 2 O、FeSO 4 ·4H 2 O、FeSO 4 ·H 2 At least one of O.
According to an embodiment of the present application, in step S1, fe is mixed in the solution 2+ The concentration of (C) is 0.001-0.4kg/L, for example 0.1-0.3kg/L.
According to an embodiment of the present application, in step S1, na is mixed in the solution + 、Fe 2+ And SO 4 2- The molar ratio of (2-6): 1-5): 2-8, for example 4:3:5, 2:2:3, 2:1:1, 6:5:8.
According to an embodiment of the present application, in step S1, the antioxidant is selected from at least one of ascorbic acid and its salts, erythorbic acid and its salts.
According to an embodiment of the application, the molar ratio of antioxidant to ferrous sulfate in step S1 is (0.01-0.5): 1, e.g. 0.1:1.
According to an embodiment of the application, the ultrasound treatment is carried out at room temperature, for example at 10-40 ℃, for example at 20-35 ℃.
Preferably, the time of the ultrasonic treatment is not particularly limited in the present application, as long as a mixed solution can be obtained. Illustratively, the time of the sonication is from 10 to 60 minutes, for example 30 minutes.
According to an embodiment of the present application, in step S1, the mixed solution is blue-green.
According to an embodiment of the application, in step S2, the outlet temperature of the spray drying is 100-150 ℃.
According to an embodiment of the present application, in step S2, the feeding amount of the mixed solution is 200 to 2000mL/h at the time of the spray drying treatment.
In step S2, according to an embodiment of the present application, spray drying may be performed using spray drying equipment known in the art.
According to an embodiment of the present application, in step S2, the solid powder is preferably white, and the metal salts of Na and Fe in the solid powder are highly dispersed at an atomic level.
According to an embodiment of the present application, in step S3, the carbon matrix material is preferably inorganic carbon. Preferably, the inorganic carbon is selected from at least one of, but not limited to, multiwall carbon nanotubes, acetylene black, ketjen black, graphene, and the like.
According to an embodiment of the present application, in step S3, the carbon matrix material accounts for 1 to 10wt%, for example, 3 to 5wt%, of the total mass of the positive electrode material precursor.
According to an embodiment of the present application, in step S3, the solid phase mixing treatment may be performed by using a solid phase mixing apparatus known in the art, for example, a solid phase mixing apparatus selected from a high-speed mixer, a ball mill, a three-dimensional mixer, and the like. The solid phase mixing treatment may be, for example, a ball milling mixing treatment such as a ball milling mixing treatment using zirconia balls in a ball mill.
Preferably, the mass ratio of the zirconia balls to the positive electrode material precursor is (1-10): 1, for example, 5:1.
Preferably, the ball-milling mixing conditions include: ball milling time is 1-10h, for example 6h; the ball milling speed is 200-800rmp, for example 500rmp.
According to an embodiment of the application, the positive electrode material precursor is a black powdery solid. In the positive electrode material precursor obtained by the solid phase mixing treatment, the solid powder in the step S2 is uniformly mixed with the carbon matrix material.
According to an embodiment of the present application, in step S4, the conditions of the pyrolysis include: pyrolysis is carried out at a pyrolysis temperature of 350-400℃for 12-24h, for example at 350℃for 12h.
Preferably, the high temperature pyrolysis is preceded by a temperature increasing treatment. Further, the temperature-increasing treatment includes increasing the temperature to the pyrolysis temperature at a temperature-increasing rate of 1 to 5 ℃/min, for example, the temperature-increasing rate is 2 ℃/min.
According to an embodiment of the application, in step S4, the oxygen-free condition is an inert atmosphere. Preferably, the inert atmosphere may be selected from inert gases known in the art, such as nitrogen.
The inventors found that due to FeSO in the feed 4 Is very easy to absorb water to form FeSO 4 ·nH 2 O, the prior known low-temperature solid phase method needs to pre-process FeSO in the raw materials 4 ·nH 2 O is dehydrated, the dehydration process is very harsh, and Fe 2+ Is extremely easy to oxidize into Fe 3+ Resulting in de-intercalation of Na into the resulting positive electrode material + Reduced capacity; moreover, feSO is obtained only by ball milling and mixing treatment 4 And Na (Na) 2 SO 4 It is difficult to achieve complete and uniform mixing at the atomic level during the ball milling process. The application is realized by adopting FeSO 4 ·nH 2 O andNa 2 SO 4 firstly, using spray drying technology to convert aqueous solution of two metal salts into powdery bi-component metal salt mixture uniformly mixed in atomic level so as to achieve the aim of mixing two metal salts in atomic level and synchronously realize FeSO 4 ·nH 2 Effect of rapid dehydration of O, and meanwhile, water molecules are rapidly separated from working environment due to spray drying, so that formation of moist atmosphere is avoided to oxidize Fe 2+ And the temperature during dehydration can be reduced so as to avoid the generation of basic ferric sulfate; the inorganic carbon matrix material and the bi-component metal salt powder obtained by spray drying are completely mixed through solid phase mixing treatment, so that the interaction between a carbon source and the bi-component metal salt powder can be enhanced, the problem that the carbon doping amount of the inorganic carbon matrix material cannot be accurately controlled in a spray drying mode due to the fact that the inorganic carbon matrix material is insoluble in water can be avoided, and a positive electrode material precursor with three components uniformly coexisting is obtained; and finally pyrolyzing the positive electrode material precursor to obtain the positive electrode material. The positive electrode material prepared by the preparation method provided by the application has excellent electrochemical comprehensive performance and is suitable for sodium ion batteries.
The application also provides the composite polyanionic ferrous sodium sulfate positive electrode material prepared by the preparation method.
According to an embodiment of the application, the composite polyanionic sodium ferrous sulfate positive electrode material comprises an active material and a carbon matrix material, wherein the molecular formula of the active material is Na x Fe y (SO 4 ) z Wherein x+2y=2z, and the ratio of x to y to z is (2-6): (1-5): (2-8).
According to an embodiment of the present application, the mass fraction of the carbon matrix material in the positive electrode material is 1 to 10wt%, for example, 5 to 10wt%, 7 to 8wt%.
According to an embodiment of the application, the ratio of x to y to z in the formula of the active substance is for example 4:3:5, 2:2:3, 2:1:2, 6:5:8.
According to an embodiment of the present application, in the positive electrode material, the active material is uniformly distributed in the carbon matrix material, as shown in fig. 1.
According to an embodiment of the present application, the composite polyanionic sodium ferrous sulfate positive electrode material has XRD characteristic diffraction peaks substantially as shown in figure 6 a.
The application also provides a positive pole piece, which comprises the positive pole material.
The application also provides application of the positive electrode material or the positive electrode plate in sodium ion batteries.
The application also provides a sodium ion battery, which comprises the positive electrode material or the positive electrode plate.
According to an embodiment of the application, the first-week discharge specific capacity of the sodium-ion battery is more than 60mAh g -1 Preferably 60-120mAh g -1 For example 87.45mAh g -1 、82.28mAh g -1 、79.63mAh g -1 、65.09mAh g -1 。
According to an embodiment of the application, the sodium ion battery capacity retention is not less than 90%, for example, 90-100%.
According to an embodiment of the application, the number of cycles of the sodium ion battery is not less than 200 cycles, for example 200-5000 cycles.
Illustratively, the sodium ion battery has a capacity retention of 98.76% or 100% after 200 cycles. According to an embodiment of the application, the sodium ion battery has high-rate charge and discharge performance, preferably has a specific discharge volume of more than 38mAh g under 5C rate charge and discharge conditions -1 。
The beneficial effects are that:
(1) According to the application, the sulphate is dissolved in water by utilizing the characteristic that the sulphate is easy to dissolve in water, and the powdery bi-component metal salt mixture with atomic level uniform mixing is obtained through spray drying, so that the operation is simple and controllable, and the time consumption is short.
(2) Anhydrous FeSO used by the existing low-temperature solid-phase ball milling method 4 Is to FeSO 4 ·nH 2 O is pre-dehydrated, and the dehydration process is uncontrollable, so that part of Fe is dehydrated 2+ Inevitably oxidized to Fe 3+ And the repeatability among different batches is extremely poor, thereby leading toThe prepared positive electrode material has larger difference in performance. In the application, na, fe and SO can be accurately controlled 4 2- The molar ratio among the three components has strong operation repeatability.
(3) Aiming at the problems that the carbon matrix material has extremely poor water solubility and is easy to agglomerate in aqueous solution, the carbon source detention phenomenon is serious during spray drying, the quantity of the carbon matrix material in the anode material is difficult to control, and the like, the application strengthens the interaction between the bi-component metal salt mixture obtained after spray drying and the carbon matrix material by utilizing solid phase mixing treatment, thereby greatly promoting Na + The carrier and the electron are synchronously transferred, so that the electrochemical performance of the positive electrode material is improved.
Drawings
FIG. 1 is an SEM image of a positive electrode material obtained in example 1 of the present application;
FIG. 2 is an SEM image of the positive electrode material obtained in comparative example 1 of the present application;
FIG. 3 is an SEM image of the positive electrode material obtained in comparative example 2 of the present application;
FIG. 4 is an SEM image of the positive electrode material obtained in comparative example 3 of the present application;
FIG. 5 is an SEM image of the positive electrode material obtained in comparative example 4 of the present application;
FIG. 6 is an XRD pattern of the positive electrode material obtained in example 1 of the present application;
FIG. 7 is an XRD pattern of the positive electrode material obtained in comparative example 1 of the present application;
FIG. 8 is an XRD pattern of the positive electrode material obtained in comparative example 2 of the present application;
FIG. 9 is an XRD pattern of the positive electrode material obtained in comparative example 3 of the present application;
FIG. 10 is an XRD pattern of the positive electrode material obtained in comparative example 4 of the present application;
FIG. 11 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in example 1 of the present application;
FIG. 12 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in comparative example 1 of the present application;
FIG. 13 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in comparative example 2 of the present application;
FIG. 14 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in comparative example 3 of the present application;
FIG. 15 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in comparative example 4 of the present application;
FIG. 16 is a graph showing the cycle performance at 1C of the positive electrode material obtained in example 1 of the present application;
FIG. 17 is a graph showing the cycle performance at 1C of the positive electrode material obtained in comparative example 1 of the present application;
FIG. 18 is a graph showing the cycle performance at 1C of the positive electrode material obtained in comparative example 2 of the present application;
FIG. 19 is a graph showing the cycle performance at 1C of the positive electrode material obtained in comparative example 3 of the present application;
FIG. 20 is a graph showing the cycle performance at 1C of the positive electrode material obtained in comparative example 4 of the present application;
FIG. 21 is a graph showing the rate performance of the positive electrode material obtained in example 1 of the present application;
FIG. 22 is a graph showing the rate performance of the positive electrode material obtained in comparative example 1 of the present application;
FIG. 23 is a graph showing the rate performance of the positive electrode material obtained in comparative example 2 of the present application;
FIG. 24 is a graph showing the rate performance of the positive electrode material obtained in comparative example 3 of the present application;
FIG. 25 is a graph showing the rate performance of the positive electrode material obtained in comparative example 4 of the present application;
FIG. 26 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in example 2 of the present application;
FIG. 27 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in example 3 of the present application;
FIG. 28 is a graph showing the first charge and discharge at 0.05C for the positive electrode material obtained in example 4 of the present application;
FIG. 29 is a graph showing the cycle performance at 1C of the positive electrode material obtained in example 2 of the present application;
FIG. 30 is a graph showing the cycle performance at 1C of the positive electrode material obtained in example 3 of the present application;
FIG. 31 is a graph showing the cycle performance at 1C of the positive electrode material obtained in example 4 of the present application;
FIG. 32 is a graph showing the rate performance of the positive electrode material obtained in example 2 of the present application;
FIG. 33 is a graph showing the rate performance of the positive electrode material obtained in example 3 of the present application;
fig. 34 is a graph showing the rate performance of the positive electrode material obtained in example 4 of the present application.
Detailed Description
The technical scheme of the application will be further described in detail below with reference to specific embodiments. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the application. All techniques implemented based on the above description of the application are intended to be included within the scope of the application.
Unless otherwise indicated, the starting materials and reagents used in the following examples were either commercially available or may be prepared by known methods.
Example 1:
20.0160g FeSO 4 ·7H 2 O，6.8179g Na 2 SO 4 Dispersing in 100mL of water solution, adding 1.2681g of ascorbic acid, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain clear and transparent blue-green mixed solution; setting the inlet temperature of spray drying equipment at 200 ℃, the fan frequency at 80Hz, the feeding speed of the mixed solution at 400mL/h, the needle penetrating speed at 5 s/time, and carrying out spray drying treatment on the mixed solution when the inlet temperature of the equipment reaches a stable state of 200+/-5 ℃ to obtain about 18g of white solid powder.
9.5g of the white solid powder, 0.5g of the multi-wall carbon nano tube (namely, the mass percentage of the multi-wall carbon nano tube is 5 percent of the total mass of the white solid powder and the carbon matrix) and 50g of zirconia balls are placed in a 100mL agate ball milling tank, and a positive electrode material precursor is obtained through ball milling treatment for 6 hours at the rotating speed of 500 r/min; transferring the obtained positive electrode material precursor into a tube furnace, heating to 350 ℃ at 2 ℃/min under nitrogen atmosphere, and sintering at constant temperature for 12 hours to obtain black powdery solid which is marked as composite polyanion sodium ferrous sulfate positive electrode material 1, wherein the positive electrode material 1 comprises active substances and carbon matrix materials, the mass fraction of the carbon matrix materials is 7.24%, and the molecular formula of the active substances is Na 4 Fe 3 (SO 4 ) 5 。
Fig. 1 is an SEM image of the positive electrode material of example 1, as can be seen from fig. 1 a: the positive electrode material of this example is formed by combining a plurality of small particles of sodium ferrous sulfate and multi-walled carbon nanotubes to form spherical secondary particles having a diameter of about 1 to 5 μm, as can be seen from fig. 1 b: the ferrous sodium sulfate particles and the multiwall carbon nanotubes (namely the marked carbon nanotubes in the b) are uniformly distributed and are in close contact with each other, so that the effect of the electron conductivity of the anode material can be obviously improved.
Fig. 6 is an XRD pattern of example 1. As can be seen from FIG. 6, the XRD characteristic diffraction peaks (a in FIG. 6) of the positive electrode material of example 1 are compared with Na 2 Fe(SO 4 ) 2 The diffraction peaks of the standard cards (PDF # 21-1360) were consistent in position and good in crystallinity.
Comparative example 1:
20.0160g FeSO 4 ·7H 2 O 7 ，6.8179g Na 2 SO 4 Dispersing in 100mL of water solution, adding 1.2681g of ascorbic acid, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain clear and transparent blue-green mixed solution; setting the inlet temperature of spray drying equipment to 200 ℃, the fan frequency to 80Hz, feeding materials for 400mL/h, the needle penetrating speed to 5 s/time, and carrying out spray drying treatment on the mixed solution to obtain about 18g of white solid powder when the inlet temperature of the equipment reaches a stable state of 200+/-5 ℃.
And transferring the white solid powder into a tube furnace, heating to 350 ℃ at 2 ℃/min under the nitrogen atmosphere, and performing constant-temperature sintering treatment for 12 hours to obtain black powdery solid, which is marked as comparative positive electrode material 1.
Fig. 2 is an SEM image of comparative cathode material 1 of comparative example 1, as can be seen from fig. 2: the comparative cathode material 1 exhibited spherical secondary particles having a diameter of about 2 to 8 μm.
Fig. 7 is an XRD pattern of the comparative cathode material 1 of comparative example 1. As can be seen from FIG. 7, the XRD characteristic diffraction peaks (a in FIG. 7) of the positive electrode material of comparative example 1 are compared with Na 2 Fe(SO 4 ) 2 The diffraction peaks of the standard cards (PDF # 21-1360) were identical in position, but were low in crystallinity. Comparison with example 1 demonstrates that the introduction of a carbon matrix material can promote the crystallinity of the positive electrode material of the present application.
Comparative example 2:
20.0160g FeSO 4 ·7H 2 O，6.8179g Na 2 SO 4 Dispersing in 100mL of water solution, adding 1.2681g of ascorbic acid and 0.9347g of multi-wall carbon nanotubes, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain black suspension (the multi-wall carbon nanotubes can be seen to be agglomerated together by naked eyes, and the dispersibility is poor); setting the inlet temperature of spray drying equipment to 200 ℃, the fan frequency to 80Hz, feeding materials for 400mL/h, the needle penetrating speed to 5 s/time, and spraying the black suspension to dry under the continuous and intense stirring state when the inlet temperature of the equipment reaches 200+/-5 ℃ in a stable state to obtain gray solid powder; and (3) transferring the precursor of the positive electrode material obtained in the previous step into a tube furnace, heating to 350 ℃ at 2 ℃/min under nitrogen atmosphere, and performing constant-temperature sintering treatment for 12 hours to obtain dark gray powdery solid which is marked as the comparative positive electrode material 2.
Fig. 3 is an SEM image of comparative cathode material 2 of comparative example 2, as can be seen from fig. 3 a: the comparative positive electrode material 2 has no apparent regular microscopic morphology, as can be seen from fig. 3 b: the contact of the sodium ferrous sulfate particles and the multi-wall carbon nano tubes is not tight, the multi-wall carbon nano tubes have obvious aggregation phenomenon, and an effective electron and/or ion transmission network cannot be constructed.
Fig. 8 is an XRD pattern of comparative positive electrode material 2 of comparative example 2. As can be seen from FIG. 8, the XRD characteristic diffraction peaks (a in FIG. 8) of the positive electrode material of comparative example 2 are compared with Na 2 Fe(SO 4 ) 2 The diffraction peaks of the standard cards (PDF # 21-1360) were identical in position, but had a high impurity phase content.
Comparative example 3:
7.2058g FeSO 4 ·7H 2 O，2.4544g Na 2 SO 4 0.3364g of multi-wall carbon nano tube and 50g of zirconia balls are placed in a 100mL agate ball milling tank and ball milled for 6 hours at the rotating speed of 500r/min to obtain a positive electrode material precursor; and transferring the precursor of the positive electrode material into a tube furnace, heating to 350 ℃ at 2 ℃/min under the nitrogen atmosphere, and performing constant-temperature sintering treatment for 12 hours to obtain black powdery solid which is marked as the comparative positive electrode material 3.
In the ball milling process, the materials are not dehydrated, so that the phenomenon that the materials adhere to the wall is serious, and the materials cannot be uniformly mixed by ball milling. Fig. 4 is an SEM image of comparative cathode material 3 of comparative example 3. As can be seen from fig. 4 a: the comparative cathode material 3 of comparative example 3 was of a spheroidal particle composition of 1-2 μm; as can be seen from fig. 4 b: the fact that the ferrous sodium sulfate particles are not connected through the multi-wall carbon nanotubes indicates that materials cannot be completely and uniformly mixed and electrons and/or ions cannot be effectively transmitted.
Fig. 9 is an XRD pattern of the comparative positive electrode material 3 of comparative example 3. As can be seen from FIG. 9, the XRD characteristic diffraction peaks (a in FIG. 9) of the positive electrode material of comparative example 3 are compared with Na 2 Fe(SO 4 ) 2 The diffraction peaks of the standard cards (PDF # 21-1360) are identical in position.
Comparative example 4:
12.0000g FeSO 4 ·7H 2 O is arranged in a tube furnace, and N is 2 Under the atmosphere, the temperature rising rate is 5 ℃/min to 300 ℃, and the anhydrous FeSO of about 6.6g is obtained after the constant temperature is kept for 10 hours 4 . 5.8550g FeSO is weighed out 4 ，3.6476g Na 2 SO 4 Placing 0.5001g of multi-wall carbon nano tube and 50g of zirconia balls into a 100mL agate ball milling tank, and ball milling for 6 hours at the rotating speed of 500r/min to obtain a positive electrode material precursor; and transferring the precursor of the positive electrode material into a tube furnace, heating to 350 ℃ at 2 ℃/min under the nitrogen atmosphere, and performing constant-temperature sintering treatment for 12 hours to obtain black powdery solid which is marked as the comparative positive electrode material 4.
Fig. 5 is an SEM image of the comparative cathode material 4 of comparative example 4, as can be seen from fig. 5 a: the comparative positive electrode material 4 is a secondary particle composed of a plurality of small particles of sodium ferrous sulfate aggregated; as can be seen from fig. 5 b: the ferrous sulfate sodium particles are in close contact with the multi-wall carbon nanotubes, the multi-wall carbon nanotubes are distributed uniformly, and synchronous transmission of electrons and ions can be realized synchronously.
Fig. 10 is an XRD pattern of the comparative positive electrode material 4 of comparative example 4. As can be seen from FIG. 10, the XRD characteristic diffraction peaks (a in FIG. 10) of the positive electrode material of comparative example 4 are compared with Na 2 Fe(SO 4 ) 2 The diffraction peaks of the standard card (PDF#21-1360) are consistent in position, but the impurity phase content is also high because part of F in the high-temperature dehydration processe 2+ Oxidized to Fe 3+ . The mass contents of the positive electrode material 1 and the comparative positive electrode materials 1 to 4 were subjected to elemental analysis using an organic elemental analyzer (model of equipment: vario EL CUBE; manufacturer: elementar, germany), and Na, fe, S, C and the like are shown in Table 1, respectively.
TABLE 1 elemental content of cathode materials
| Elemental content | Na/％ | Fe/％ | S/％ | C/％ |
| Cathode material 1 | 9.76 | 18.81 | 19.49 | 7.24 |
| Comparative cathode Material 1 | 9.77 | 18.99 | 21.36 | 1.85 |
| Comparative cathode Material 2 | 9.74 | 22.23 | 20.47 | 6.43 |
| Comparative cathode Material 3 | 10.18 | 21.22 | 20.05 | 5.69 |
| Comparative cathode Material 4 | 8.98 | 22.51 | 20.35 | 5.37 |
As can be seen from Table 1 and SEM images, the positive electrode material prepared by the preparation method provided by the application has higher carbon content and more uniform distribution of sodium ferrous sulfate particles in the carbon nanotubes; whereas the cathode materials of comparative examples 1 to 4, and particularly comparative example 2, have low carbon content, it can be confirmed that the carbon matrix material suffers from serious carbon retention problems during spray drying.
Application example 1
The preparation method of the positive plate comprises the following specific steps:
the positive electrode materials of the example 1 and the comparative examples 1-4 are respectively taken, the positive electrode materials, acetylene black and polyvinylidene fluoride are dispersed in an N-methyl pyrrolidone solvent according to the mass ratio of 8:1:1, and are fully mixed and prepared into slurry, the slurry is uniformly coated on an aluminum foil, and the aluminum foil is dried in vacuum at 120 ℃ and then cut to obtain positive electrode plates which are respectively marked as a positive electrode plate 1, a comparative electrode plate 2, a comparative electrode plate 3 and a comparative electrode plate 4.
Assembled 2016 type button cell: respectively taking a positive pole piece 1, a comparison pole piece 2, a comparison pole piece 3 and a comparison pole piece 4, wherein a pure Na piece is taken as a negative pole piece, and a polypropylene diaphragm separates the positive pole piece from the negative pole piece, and the NaPF is 0.6M 6 The PC/EMC/FEC is electrolyte, the stainless steel shell is a shell, and the 2016-type button battery is assembled and is respectively marked as a battery 1, a comparison battery 1,Comparative battery 2, comparative battery 3, comparative battery 4.
Test example 1
1. And (3) testing charge and discharge performance: the above cell 1 and comparative cells 1-4 were subjected to a reaction of 2.0-4.5V (vs.Na + Na) potential interval, current density was 0.05C, and charge and discharge tests were performed, with the test results shown in fig. 11 to 15, respectively.
As shown in FIGS. 11-15, the positive electrode material of example 1 has a specific capacity of 87.45mAh g at 0.05C at the initial discharge -1 Is obviously better than that of comparative example 1 (FIG. 12, 80.50mAh g -1 ) Comparative example 2 (FIG. 13, 69.50mAh g) -1 ) Comparative example 3 (FIG. 14, 64.89mAh g -1 ) And comparative example 4 (FIG. 15, 69.90mAh g -1 ) Specific capacity of the first week of discharge.
2. Cycling stability and capacity retention: the above cell 1 and comparative cells 1-4 were subjected to a reaction of 2.0-4.5V (vs.Na + Na) potential interval, the current density was 1C, and charge and discharge tests were performed, and the test results are shown in fig. 16 to 20, respectively.
As shown in fig. 16, the composite polyanionic sodium ferrous sulfate positive electrode material prepared by coupling the spray drying, solid phase ball milling mixing and low temperature pyrolysis reaction process in example 1 has the best cycling stability under 1C, and after 200 cycles, the capacity retention rate is as high as 98.76%; specific discharge capacity of about 80mAh g -1 The method comprises the steps of carrying out a first treatment on the surface of the In comparative example 1 (see FIG. 17, capacity retention was 98.59%; specific discharge capacity was about 45mAh g) -1 ) Comparative example 2 (see fig. 18, capacity retention ratio 88.42%; specific discharge capacity of about 35mAh g -1 ) Comparative example 3 (see fig. 19, capacity retention ratio 94.67%; specific discharge capacity of about 60mAh g -1 ) And comparative example 4 (see fig. 20, capacity retention of 95.54%; specific discharge capacity of about 65mAh g -1 ) Specific discharge capacity, cycling stability and capacity retention under comparable test conditions were far less than in example 1.
3. Multiplying power test: the above cell 1 and comparative cells 1-4 were subjected to a reaction of 2.0-4.5V (vs.Na + Carrying out multiplying power charge and discharge for 2 circles under the current density of 0.05C in a Na) potential interval, and activating the battery; then respectively and sequentially carrying out current density of 0.1C, 0.2C and 0.5C. 1C, 2C, 3C, 4C, 5C, 1C were subjected to a rate charge and discharge test (5 cycles per current density condition), and the rate discharge test results of the battery 1 and the comparative batteries 1 to 4 are shown in FIGS. 21 to 25, FIG. 21 shows the rate performance of the positive electrode material of example 1, and the battery 1 was better in rate performance under a 5C rate charge and discharge condition and had a specific discharge capacity of 42.78mAh g -1 The method comprises the steps of carrying out a first treatment on the surface of the The specific discharge volume of the comparative batteries 1-4 is less than 37mAh g under the condition of 5C multiplying power charge and discharge -1 。
According to the test, the positive electrode material prepared by the preparation method of coupling spray drying with solid phase mixing and low-temperature pyrolysis reaction processes can strengthen interaction among three raw materials, and can remarkably improve electrochemical performance of the positive electrode material.
Example 2:
20.0160g FeSO 4 ·7H 2 O，5.1134g Na 2 SO 4 Dispersing in 100mL of water solution, adding 1.2681g of ascorbic acid, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain clear and transparent blue-green solution; setting the inlet temperature of spray drying equipment to 200 ℃, the fan frequency to 80Hz, feeding materials for 400mL/h, and the needle passing speed to 5 s/time, and spraying the configured blue-green solution to obtain white solid powder when the inlet temperature of the equipment reaches a stable state of 200+/-5 ℃; 9.5g of the obtained white solid powder, 0.5g of multi-wall carbon nano tube (the mass of the multi-wall carbon nano tube is 5% of the total mass of the white solid powder and the carbon matrix) and 50g of zirconia balls are placed in an agate ball milling tank which is 100mL, and ball milling is carried out for 6 hours at the rotating speed of 500r/min to obtain a positive electrode material precursor; transferring the precursor of the positive electrode material obtained in the previous step into a tube furnace, heating to 350 ℃ at 2 ℃/min under nitrogen atmosphere, and keeping the temperature for 12 hours to obtain a black powdery compound polyanion sodium ferrous sulfate positive electrode material 2, wherein the positive electrode material comprises an active substance and a carbon matrix material, the mass fraction of the carbon matrix material is 7.20%, and the molecular formula of the active substance is Na 2 Fe 2 (SO 4 ) 3 。
Example 3:
20.0160g FeSO 4 ·7H 2 O，10.2269g Na 2 SO 4 Dispersed in 100mL of waterAdding 1.2681g of ascorbic acid into the solution, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain a clear and transparent blue-green solution; setting the inlet temperature of spray drying equipment to 200 ℃, the fan frequency to 80Hz, feeding materials for 400mL/h, and the needle passing speed to 5 s/time, and spraying the configured blue-green solution to obtain white solid powder when the inlet temperature of the equipment reaches a stable state of 200+/-5 ℃; 9.5g of the obtained white solid powder, 0.5g of multi-wall carbon nano tube (the mass of the multi-wall carbon nano tube is 5% of the total mass of the white solid powder and the carbon matrix) and 50g of zirconia balls are placed in a 100mL agate ball milling tank, and ball milling is carried out for 6 hours at the rotating speed of 500r/min to obtain a positive electrode material precursor; transferring the precursor of the positive electrode material obtained in the previous step into a tube furnace, heating to 350 ℃ at 2 ℃/min under nitrogen atmosphere, and keeping the temperature for 12 hours to obtain a black powdery compound polyanion sodium ferrous sulfate positive electrode material 3, wherein the positive electrode material comprises an active substance and a carbon matrix material according to the test of an organic element analyzer, the mass fraction of the carbon matrix material is 7.09%, and the molecular formula of the active substance is Na 2 Fe(SO 4 ) 2 。
Example 4:
20.0160g FeSO 4 ·7H 2 O，6.1361g Na 2 SO 4 Dispersing in 100mL of water solution, adding 1.2681g of ascorbic acid, and performing ultrasonic treatment at room temperature (20-35 ℃) for 30min to obtain clear and transparent blue-green solution; setting the inlet temperature of spray drying equipment to 200 ℃, the fan frequency to 80Hz, feeding materials for 400mL/h, and the needle passing speed to 5 s/time, and spraying the configured blue-green solution to obtain white solid powder when the inlet temperature of the equipment reaches a stable state of 200+/-5 ℃; 9.5g of the obtained white solid powder, 0.5g of multi-wall carbon nano tube (the mass of the multi-wall carbon nano tube is 5% of the total mass of the white solid powder and the carbon matrix) and 50g of zirconia balls are placed in a 100mL agate ball milling tank, and ball milling is carried out for 6 hours at the rotating speed of 500r/min to obtain a positive electrode material precursor; transferring the precursor of the positive electrode material obtained in the previous step into a tube furnace, heating to 350 ℃ at 2 ℃/min under nitrogen atmosphere, and keeping the temperature for 12 hours to obtain a black powdery compound polyanion sodium ferrous sulfate positive electrode material 4, wherein the positive electrode material comprises an active substance and a carbon matrix material according to the test of an organic element analyzer, the mass fraction of the carbon matrix material is 7.48%, and the molecular formula of the active substance is Na 6 Fe 5 (SO 4 ) 8 。
The positive electrode materials obtained in examples 2 to 4 had spherical secondary particles substantially as shown in fig. 1, and sodium ferrous sulfate particles and multiwall carbon nanotubes were uniformly distributed and closely contacted with each other; the XRD pattern of the positive electrode material is substantially the same as that of a in fig. 6, and the crystallinity is good.
Application example 2
The composite polyanionic sodium ferrous sulfate positive electrode materials of examples 2-4 were taken respectively, and positive electrode sheets and batteries were prepared with reference to application example 1, and were respectively denoted as positive electrode sheets 2-4 and batteries 2-4.
Test example 2
Referring to the test method of test example 1, the electrochemical properties of batteries 2 to 4 were respectively tested, and the test results are respectively shown in fig. 26 to 34, and the test data of batteries 1 to 4 are summarized in table 2.
Table 2 electrochemical performance of cells 1-4
| Battery cell | Specific discharge capacity of 0.05C first turn | Circulation stability | Capacity retention rate | Multiplying power performance (5C) |
| Battery 1 | 87.45mAh g -1 | 200 circles | 98.76％ | 42.78mAh g -1 |
| Battery 2 | 82.28mAh g -1 | 200 circles | 100％ | 38.35mAh g -1 |
| Battery 3 | 79.63mAh g -1 | 200 circles | 100％ | 50.18mAh g -1 |
| Battery 4 | 65.09mAh g -1 | 200 circles | 100％ | 42.10mAh g -1 |
As shown in Table 2, the batteries 1-4 all show excellent cycling stability (the cycling rate of 200 circles under the current density of 1C is over 95 percent, the specific discharge capacity of the batteries under the current density of 5C can be over 50 percent of the specific discharge capacity under the current density of 1C, and the specific discharge capacity of the batteries is basically equivalent to the original capacity under the current density of 1C after the batteries are converted from the current density of 5C to the current density of 1C), so that the spray drying process coupled with the solid-phase mixing and low-temperature pyrolysis reaction process has strong universality, and an effective electron and/or ion transmission network is constructed in the prepared positive electrode material, so that the electrons and/or ions can be effectively transmitted.
The above description of exemplary embodiments of the application has been provided. However, the scope of the present application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, or the like, which are within the spirit and principles of the present application, should be made by those skilled in the art, and are intended to be included within the scope of the present application.
Claims (10)
1. The preparation method of the composite polyanionic ferrous sodium sulfate positive electrode material is characterized by comprising the following steps of:
s1: uniformly dissolving sodium sulfate and ferrous sulfate in water, adding an antioxidant, and performing ultrasonic treatment to obtain a mixed solution;
s2: carrying out spray drying treatment on the mixed solution obtained in the step S1 to obtain solid powder;
s3: the solid powder obtained in the step S2 is subjected to solid phase mixing treatment with a carbon matrix material to obtain a positive electrode material precursor;
s4: and (3) carrying out high-temperature pyrolysis on the positive electrode material precursor obtained in the step (S3) under the anaerobic condition to obtain the composite polyanion sodium ferrous sulfate positive electrode material.
2. The method according to claim 1, wherein in step S1, the ferrous sulfate is selected from ferrous sulfate or a crystalline hydrate of ferrous sulfate;
and/or, in step S1, fe in the mixed solution 2+ The concentration of (2) is 0.001-0.4kg/L;
and/or, in step S1, na is contained in the mixed solution + 、Fe 2+ And SO 4 2- The molar ratio of (2-6): 1-5): 2-8;
and/or, in step S1, the antioxidant is selected from at least one of ascorbic acid and its salts, isoascorbic acid and its salts;
and/or the molar ratio of the antioxidant to the ferrous sulfate in the step S1 is (0.01-0.5): 1.
3. The method of claim 1, wherein in step S2, the spray-dried outlet temperature is 100-150 ℃;
and/or in the step S2, the feeding amount of the mixed solution is 200-2000mL/h during spray drying treatment;
and/or, in the step S2, the solid powder is white, and the Na and Fe metal salts in the solid powder are highly dispersed at an atomic level.
4. The method according to claim 1, wherein in step S3, the carbon matrix material is inorganic carbon;
and/or, in step S3, the carbon matrix material accounts for 1-10wt% of the total mass of the positive electrode material precursor;
and/or, the ball milling mixing conditions include: ball milling time is 1-10h; ball milling rotation speed is 200-800rmp;
and/or the positive electrode material precursor is black powdery solid.
5. The method according to claim 1, wherein in step S4, the conditions of the pyrolysis include: pyrolyzing at a pyrolysis temperature of 350-400 ℃ for 12-24h;
and/or, in step S4, the anaerobic condition is an inert atmosphere.
6. The composite polyanionic ferrous sodium sulfate positive electrode material obtained by the preparation method of any one of claims 1 to 5.
7. The positive electrode material according to claim 6, wherein the composite polyanionic sodium ferrous sulfate positive electrode material comprises an active material and a carbon matrix material, the active material having a molecular formula of Na x Fe y (SO 4 ) z Wherein x+2y=2z, and the ratio of x to y to z is (2-6): 1-5): 2-8;
and/or, in the positive electrode material, the mass fraction of the carbon matrix material is 1-10wt%.
8. A positive electrode sheet, characterized in that it comprises the positive electrode material according to claim 6 or 7.
9. Use of the positive electrode material of claim 6 or 7 or the positive electrode sheet of claim 8 in a sodium ion battery.
10. A sodium ion battery comprising the positive electrode material of claim 6 or 7 or the positive electrode sheet of claim 8.
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| CN117239138A (en) * | 2023-11-15 | 2023-12-15 | 华北电力大学 | Sodium ion battery positive electrode material, preparation method thereof and sodium ion battery |
| CN117239138B (en) * | 2023-11-15 | 2024-01-23 | 华北电力大学 | Sodium ion battery positive electrode material, preparation method thereof and sodium ion battery |
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