CN115403079A - Positive electrode precursor material and preparation method and application thereof - Google Patents
Positive electrode precursor material and preparation method and application thereof Download PDFInfo
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- 239000002243 precursor Substances 0.000 title claims abstract description 100
- 239000000463 material Substances 0.000 title claims abstract description 91
- 238000002360 preparation method Methods 0.000 title abstract description 23
- 239000002245 particle Substances 0.000 claims abstract description 42
- 239000011247 coating layer Substances 0.000 claims abstract description 27
- 239000011159 matrix material Substances 0.000 claims abstract description 13
- 238000006243 chemical reaction Methods 0.000 claims description 118
- 239000000243 solution Substances 0.000 claims description 70
- 239000012266 salt solution Substances 0.000 claims description 60
- 238000000975 co-precipitation Methods 0.000 claims description 55
- 239000011572 manganese Substances 0.000 claims description 53
- 239000007774 positive electrode material Substances 0.000 claims description 46
- 239000012716 precipitator Substances 0.000 claims description 38
- 239000007864 aqueous solution Substances 0.000 claims description 25
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 22
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 10
- 239000010949 copper Substances 0.000 claims description 9
- 230000002093 peripheral effect Effects 0.000 claims description 8
- 239000012798 spherical particle Substances 0.000 claims description 8
- 239000003638 chemical reducing agent Substances 0.000 claims description 7
- 239000011734 sodium Substances 0.000 claims description 7
- 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 6
- 150000001875 compounds Chemical class 0.000 claims description 6
- 150000002696 manganese Chemical class 0.000 claims description 6
- 229910052708 sodium Inorganic materials 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- 238000001354 calcination Methods 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 150000001879 copper Chemical class 0.000 claims description 3
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 3
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- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000009286 beneficial effect Effects 0.000 abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 79
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 51
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 45
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 30
- 238000005406 washing Methods 0.000 description 29
- 238000003756 stirring Methods 0.000 description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 20
- 229910001415 sodium ion Inorganic materials 0.000 description 18
- 239000013078 crystal Substances 0.000 description 17
- 229910052751 metal Inorganic materials 0.000 description 17
- 239000002184 metal Substances 0.000 description 17
- 230000000052 comparative effect Effects 0.000 description 15
- 229910000029 sodium carbonate Inorganic materials 0.000 description 15
- 239000011790 ferrous sulphate Substances 0.000 description 14
- 235000003891 ferrous sulphate Nutrition 0.000 description 14
- 229910000359 iron(II) sulfate Inorganic materials 0.000 description 14
- 229940099596 manganese sulfate Drugs 0.000 description 14
- 239000011702 manganese sulphate Substances 0.000 description 14
- 235000007079 manganese sulphate Nutrition 0.000 description 14
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 14
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 description 13
- 239000007788 liquid Substances 0.000 description 13
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 12
- 150000002500 ions Chemical class 0.000 description 12
- 238000001035 drying Methods 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 description 10
- 239000008367 deionised water Substances 0.000 description 10
- 229910021641 deionized water Inorganic materials 0.000 description 10
- 239000011259 mixed solution Substances 0.000 description 10
- 229910052757 nitrogen Inorganic materials 0.000 description 10
- 230000032683 aging Effects 0.000 description 8
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 8
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- 239000001301 oxygen Substances 0.000 description 7
- 229910052760 oxygen Inorganic materials 0.000 description 7
- 229910000365 copper sulfate Inorganic materials 0.000 description 6
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 229910052759 nickel Inorganic materials 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 238000001878 scanning electron micrograph Methods 0.000 description 4
- 229910002551 Fe-Mn Inorganic materials 0.000 description 3
- 238000011161 development Methods 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000011267 electrode slurry Substances 0.000 description 3
- 238000009830 intercalation Methods 0.000 description 3
- 238000005457 optimization Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 238000007086 side reaction Methods 0.000 description 3
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 2
- 230000002776 aggregation Effects 0.000 description 2
- 239000006183 anode active material Substances 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
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- 239000006258 conductive agent Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- FPBMTPLRBAEUMV-UHFFFAOYSA-N nickel sodium Chemical compound [Na][Ni] FPBMTPLRBAEUMV-UHFFFAOYSA-N 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000011149 active material 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
- 238000004458 analytical method Methods 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000011258 core-shell material Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910001416 lithium ion Inorganic materials 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000036961 partial effect Effects 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000002829 reductive effect Effects 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/40—Nickelates
- C01G53/42—Nickelates containing alkali metals, e.g. LiNiO2
- C01G53/44—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese
- C01G53/50—Nickelates containing alkali metals, e.g. LiNiO2 containing manganese of the type [MnO2]n-, e.g. Li(NixMn1-x)O2, Li(MyNixMn1-x-y)O2
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G45/00—Compounds of manganese
- C01G45/12—Manganates manganites or permanganates
- C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
- C01G45/1228—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type [MnO2]n-, e.g. LiMnO2, Li[MxMn1-x]O2
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
- H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
- H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a positive electrode precursor material and a preparation method and application thereof, wherein the positive electrode precursor material consists of aNi 1‑ 2x Mn x Fe x (OH) 2 ·bCu y Fe z Mn 1‑y‑z CO 3 ，a+b＝1,0.3≤a≤0.8，0.2≤b≤0.7，0<x is less than or equal to 0.4, y is less than or equal to 0.1 and less than or equal to 0.4, and z is more than or equal to 0.2 and less than or equal to 0.5; wherein the positive electrode precursor material comprises Ni 1‑2x Mn x Fe x (OH) 2 Matrix particles and Cu y Fe z Mn 1‑y‑z A coating layer, at least a part of the surface of the base particle being covered with the coating layer. The positive electrode precursor material is beneficial to improving secondary batteries, especially sodiumCycling performance and energy density of the ion battery.
Description
Technical Field
The invention relates to a positive electrode precursor material, in particular to a positive electrode precursor material and a preparation method and application thereof, belonging to the technical field of secondary battery materials.
Background
In recent years, with the gradual exposure of problems such as scarcity, uneven distribution, difficulty in development and utilization of lithium resources, sodium ion batteries have greater market competitive advantages and development prospects in terms of cost, resources, energy consumption and the like. But in contrast to lithium ions
Radius of sodium ion
Larger and slower diffusion kinetics, which makes it have intrinsic disadvantages in energy density and cycle characteristics, solving the energy density and cycle performance of sodium ion batteries is a key to the long-term development of sodium ion batteries, and one of the most promising approaches to solve this problem is to develop high nickel sodium ion batteries.
However, the currently available high nickel sodium ion batteries have significant disadvantages, for example, high nickel may cause the mixed-discharging effect inside the positive electrode material, reduce the diffusion rate of sodium ions, and cause poor performance during discharging; or, the high nickel anode material has poor air stability and is easy to react with H in the environment 2 O、CO 2 And the like, to inhibit the desorption of sodium ions.
Therefore, how to obtain a sodium ion cathode material with high energy density and good cycle performance is a technical problem to be solved urgently.
Disclosure of Invention
The invention provides a positive electrode precursor material, and the special composition and structure of the material are beneficial to improving the cycle performance and energy density of a secondary battery, particularly a sodium ion battery.
The invention also provides a preparation method of the anode precursor material, which can obtain the anode precursor material for improving the cycle performance and the energy density of a secondary battery, particularly a sodium-ion battery, and has the advantages of simplicity and easy operation.
The invention also provides a positive active material, and the special composition and structure of the positive active material are beneficial to improving the cycle performance and energy density of a secondary battery, especially a sodium ion battery.
The invention provides a positive electrode precursor material, which comprises aNi 1-2x Mn x Fe x (OH) 2 ·bCu y Fe z Mn 1-y-z CO 3 A + b =1,0.3 is more than or equal to a and less than or equal to 0.8,0.2 is more than or equal to b and less than or equal to 0.7, x is more than 0 and less than or equal to 0.4, y is more than or equal to 0.1 and less than or equal to 0.4, and z is more than or equal to 0.2 and less than or equal to 0.5; wherein, the first and the second end of the pipe are connected with each other,
the positive electrode precursor material includes Ni 1-2x Mn x Fe x (OH) 2 Matrix particles and Cu y Fe z Mn 1-y-z A coating layer, at least a part of the surface of the base particle being covered with the coating layer.
The positive electrode precursor material is spherical particles or spheroidal particles.
The positive electrode precursor material described above, wherein the Dv50 of the positive electrode precursor material is 2.5 to 5 μm.
The positive electrode precursor material as described above, wherein the coating layer has a thickness of 0.2 to 1 μm.
The positive electrode precursor material as described above, wherein the matrix particles are spherical particles or spheroidal particles;
the base particle includes an inner core portion and an outer peripheral portion located at the outer periphery of the inner core portion, and the porosity of the inner core portion is smaller than that of the outer peripheral portion.
The invention also provides a preparation method of any one of the positive electrode precursor materials, which comprises the following steps:
after a first mixed salt solution containing nickel salt, ferrous salt and manganese salt is subjected to a first coprecipitation reaction by using a first precipitator solution, respectively introducing a second mixed salt solution and a second precipitator solution into the system to perform a second coprecipitation reaction, thereby obtaining the anode precursor material;
the first precipitator solution is an aqueous solution containing hydroxyl, the second mixed salt solution contains copper salt, ferrous salt and manganese salt, and the second precipitator solution is a carbonate aqueous solution.
The preparation method as described above, wherein the reaction solution of the first coprecipitation reaction and the second coprecipitation reaction contains a reducing agent.
The preparation method as described above, wherein, in the first coprecipitation reaction and the second coprecipitation reaction, the reaction temperature is 55-70 ℃, and the pH value is 10-12.
The invention also provides a positive active material, and the composition of the positive active material is [ aNaNi ] 1- 2x Mn x Fe x O 2 ]·[bNaCu y Fe z Mn 1-y-z O 2 ]，a+b＝1,0.3≤a≤0.8，0.2≤b≤0.7，0<x≤0.4，0.1≤y≤0.4，0.2≤z≤0.5。
The positive electrode active material as described above, wherein the positive electrode active material is obtained by a production method comprising:
and mixing and calcining the positive electrode precursor material and a sodium-containing compound to obtain the positive electrode active material.
According to the invention, through limiting and modifying the composition and structure of the positive electrode precursor particles, the extraction capacity of active ions is improved by taking chemical property optimization and physical isolation as entry points, the probability of side reactions with water, oxygen and electrolyte is reduced, and the energy density, structural stability and chemical stability of the positive electrode active material derived from the positive electrode precursor particles are improved to a certain extent. Therefore, the positive electrode precursor particles of the present invention are advantageous for achieving optimization of cycle performance and energy density of a secondary battery.
Drawings
FIG. 1 is a scanning electron micrograph of a positive electrode precursor material in example 1 of the present invention;
FIG. 2 is a scanning electron micrograph of a positive electrode precursor material according to comparative example 1 of the present invention;
fig. 3 is a graph of the cycle performance of a sodium ion battery of the present invention obtained from the positive electrode precursor material in example 1;
fig. 4 is a graph showing the cycle characteristics of the sodium-ion battery according to the present invention obtained from the positive electrode precursor material in comparative example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The invention provides a positive electrode precursor material, the composition of the positive electrode precursor is aNi 1- 2x Mn x Fe x (OH) 2 ·bCu y Fe z Mn 1-y-z CO 3 ，a+b＝1,0.3≤a≤0.8，0.2≤b≤0.7，0<x is less than or equal to 0.4, y is less than or equal to 0.1 and less than or equal to 0.4, and z is less than or equal to 0.5 and less than or equal to 0.2; wherein the content of the first and second substances,
the positive electrode active material includes Ni 1-2x Mn x Fe x (OH) 2 Matrix particles and Cu y Fe z Mn 1-y-z A coating layer, at least a part of the surface of the base particle being covered with the coating layer.
The positive electrode precursor material aNi of the invention 1-2x Mn x Fe x (OH) 2 ·bCu y Fe z Mn 1-y-z CO 3 Is a layered structure comprising matrix particles Ni 1-2x Mn x Fe x (OH) 2 And a clad Cu y Fe z Mn 1-y-z 。
According to the above-described aspect of the present invention, when the positive electrode active material obtained by oxidatively intercalating active ions (mixing and calcining the active ion-containing compound) into the positive electrode precursor material of the present invention is applied to a secondary battery (particularly, a sodium ion battery), the cycle performance and energy density of the secondary battery can be significantly improved. Based on this phenomenon analysis, the inventors considered that it is possible to: from the physical isolation point of view, on one hand, the coating layer with the composition is beneficial to isolating the matrix particles from external electrolyte to a certain extent and only allowing active ions to pass through, thereby effectively reducing the probability of side reaction of the electrolyte and the matrix particles and playing a certain stabilizing effect and an ion conducting effect on an electrode/electrolyte interface; on the other hand, the coating layer with the composition has certain inertia to water and oxygen in the air after the operation of oxidizing and embedding the active ions, so that structural collapse and generation of an active ion passivation layer caused by side reaction with the water and oxygen can be avoided in the battery assembly process, and the diffusion performance of the active ions is further improved; from the viewpoint of chemical performance, the special element composition and the proportion among elements of the positive electrode precursor material enable the positive electrode active material to have a stable crystal structure which is easy for active ions to be extracted, so that excellent energy density and cycle performance are shown.
Therefore, due to the protection of the coating layer and the special element composition of the precursor, the positive active material derived from the precursor material has certain inertness to external water oxygen and electrolyte in the assembling and circulating processes of the secondary battery, so that the secondary battery can still show excellent circulating performance in the long-term application process even if the positive active material has high nickel content.
In one embodiment, the positive electrode precursor material of the present invention is spherical particles or spheroidal particles. The inventors have found that the cycle performance of the battery is more excellent when the positive electrode active material in the battery is derived from a spherical or spheroidal positive electrode precursor material, as compared to other shapes (e.g., pellet-like). On one hand, the spherical or spheroidal particles can effectively avoid agglomeration, thereby not only enhancing the structural stability of the anode active material, but also improving the stacking density; on the other hand, the spherical or spheroidal particles may be more favorable for the de-intercalation and diffusion of active ions.
Further, the Dv50 of the positive electrode precursor material of the present invention is 2.5 to 5 μm. The particle size can avoid agglomeration among the anode precursor materials, and the derived anode active material has enough surface area for de-intercalation of active ions, so that the cycle performance and the energy density of the battery are facilitated. The Dv50 in the present invention is the median particle diameter.
The thickness of the coating layer, which serves as a barrier outside the matrix particles, is also an important factor affecting the performance of the battery. The invention can furthest play the role of protecting the matrix particles by the coating layer on the premise of ensuring the normal diffusion of active ions by controlling the radial thickness of the coating layer to be 0.2-1 mu m.
It can be understood that when the base particles are spherical particles or spheroidal particles, it is advantageous to obtain a positive electrode precursor material having spherical particles or spheroidal particles. The inventors have found that the porosity of the matrix particles also has some effect on the cycling performance of the final battery.
Specifically, the spherical particles or the spheroidal matrix particles include an inner core portion and an outer peripheral portion located at the outer periphery of the inner core portion, and when the porosity of the inner core portion is smaller than that of the outer peripheral portion, more stable growth of a subsequent coating layer is facilitated, so that the advantage that the coating layer blocks electrolyte and external water oxygen can be further exerted. Taking the diameter of the spherical or spheroidal positive electrode precursor material as D for example, the inner core part has D Inner part Spherical or spheroidal particles of diameter, the peripheral portion surrounding and enveloping the inner portion, the radial dimension D of the peripheral portion Outer cover And D Inner part The sum being equal to D, D Inner part Typically 60% to 96% of D.
The second aspect of the present invention provides a method for preparing a positive electrode precursor material, including the steps of:
after a first mixed salt solution containing nickel salt, ferrous salt and manganese salt is subjected to a first coprecipitation reaction by using a first precipitator solution, respectively introducing a second mixed salt solution and a second precipitator solution into the system to perform a second coprecipitation reaction, thereby obtaining the anode precursor material;
the first precipitator solution is an aqueous solution containing hydroxyl, the second mixed salt solution contains copper salt, ferrous salt and manganese salt, and the second precipitator solution is an aqueous solution of carbonate.
In the present invention, a first mixed salt solution is used to provide the active metal in the base particle, a second mixed salt solution is used to provide the active metal in the coating layer, a first precipitant is used to co-precipitate the active metal in the first mixed salt solution in the form of hydroxide (i.e., a first co-precipitation reaction), and a second precipitant is used to co-precipitate the active metal in the second mixed salt solution in the form of carbonate (i.e., a second co-precipitation reaction). It can be understood that, in order to obtain the coating of the metal carbonate on the metal hydroxide, after the first coprecipitation is finished, the second mixed salt solution and the second precipitant solution are respectively introduced into the first coprecipitation system.
The present invention is not limited to the specific expression of the active metal salt in the first mixed salt solution and the second mixed salt solution, and the active metal salt may be, for example, a nitrate, an acetate, a sulfate, or the like of the active metal. Further, the ratio between the respective metal salts may be determined according to the target product.
The first precipitant solution may be, for example, an aqueous solution of sodium hydroxide, and further may be an aqueous solution of 5 to 8mol/L sodium hydroxide; the second precipitant solution may be, for example, an aqueous solution of sodium carbonate, and further, may be an aqueous solution of 3 to 6mol/L of sodium carbonate.
In a specific implementation process, the first mixed salt solution, the first precipitant solution, the second mixed salt solution, and the second precipitant solution may be prepared first. And then introducing the first mixed salt solution and the first precipitator solution into a reaction kettle containing deionized water to perform a first co-precipitation reaction. And after the first coprecipitation reaction is finished, introducing a second mixed salt solution and a second precipitator solution into the system of the first coprecipitation reaction to carry out a second coprecipitation reaction. And after the second coprecipitation reaction is finished, carrying out post-treatment including solid-liquid separation, washing, drying and the like on the reaction liquid to obtain the anode precursor material.
In the above preparation process, in order to avoid partial oxidation of the metal, a protective gas, such as nitrogen, argon, etc., needs to be introduced into the reaction kettle simultaneously.
In addition, 5-8mol/L ammonia water solution can be introduced into the system in the first coprecipitation reaction, so that homogeneous precipitation of coprecipitation is further ensured.
In one embodiment, the first mixed salt solution has a molar concentration of 1 to 2mol/L and/or the second mixed salt solution has a molar concentration of 0.5 to 1mol/L. The molar concentration refers to the total molar concentration of the active metal salt in the salt solution. Further, the ratio between the respective metal salts in the first mixed salt solution and the second mixed salt solution may be determined according to the target product. For example, the molar ratio of Ni to Mn to Fe in the first mixed salt solution is 0.4 to 1.0.
The inventors found that when the reaction solution of the first coprecipitation reaction and the second coprecipitation reaction contains a reducing agent, part of the active metals (e.g., ferrous iron, manganese) in the reaction solution can be effectively prevented from being oxidized, thereby enabling further optimization of the relevant electrical properties of the battery. For example, the reducing agent may be citric acid. Specifically, the reducing agent is added to the first mixed salt solution and the second mixed salt solution, respectively, and the concentration in each salt solution is, for example, 1g/L. The addition form of the reducing agent is not limited in the invention, and the reducing agent can be directly added or added after being prepared into an aqueous solution.
In the preparation process, the reaction temperature of the reaction system of the first coprecipitation reaction and the second coprecipitation reaction is 55-70 ℃, and the pH value is 10-12.
As for other process parameters in the above preparation process, such as feed flow rate, stirring speed during co-precipitation reaction, reaction time, etc., it can be presumed according to a crystal particle growth kinetic model, and the process parameters can be adjusted in time by monitoring the crystal particles in real time during the preparation process, so as to obtain the positive electrode precursor particles meeting the target parameters (particle size, porosity).
Illustratively, in the first coprecipitation reaction, the feeding flow rate of the first mixed salt solution is 10-100L/h, the feeding flow rate of the first precipitant solution is 15-35L/h, the feeding flow rate of the ammonia water is 20-200mL/min, and the stirring linear velocity is 200-600r/s; in the second coprecipitation reaction, the feeding flow rate of the second mixed salt solution is 40-55L/h, and the feeding flow rate of the second precipitator solution is 5-20L/h, and the stirring linear speed is 150-300r/s.
In addition, the respective reaction time of the first coprecipitation reaction and the second coprecipitation reaction can be determined according to the size of the system, and the reaction can be stopped after the complete precipitation reaction is ensured.
The present invention is not limited to the specific parameters of the above-mentioned post-treatment including solid-liquid separation, washing and drying. For example, the reaction solution of the second coprecipitation reaction is subjected to solid-liquid separation by centrifugation or filtration, the solid phase precipitate is collected and washed with deionized water until the pH of the washing water is less than 8, and then the washed solid phase precipitate is dried at 80 to 120 ℃ to obtain the positive electrode precursor material.
The third aspect of the present invention provides a positive electrode active material having a composition of [ aNaNi ] 1- 2x Mn x Fe x O 2 ]·[bNaCu y Fe z Mn 1-y-z O 2 ]，a+b＝1,0.3≤a≤0.8，0.2≤b≤0.7，0<x≤0.4，0.1≤y≤0.4，0.2≤z≤0.5。
The positive electrode active material has NaNi 1-2x Mn x Fe x O 2 And NaCu coated on at least part of the outer surface of the base particle 0.2 Fe 0.3 Mn 0.5 O 2 And (4) coating.
From the composition, it can be found that the positive electrode active material has the same composition and structure of the active metal as the positive electrode precursor material of the foregoing first aspect, and therefore the positive electrode active material can effectively improve the cycle performance and energy density of the secondary battery.
The positive electrode active material of the present invention is obtained by mixing and calcining the positive electrode precursor material of the first aspect and the sodium-containing compound.
Wherein, naOH, naF, na can be adopted 2 CO 3 And CH 3 One or more of COONa is used as the sodium-containing compound. After the positive electrode precursor particles and the sodium-containing compound are mixed, the mixture can be subjected to heat preservation for 6 hours at 400-800 ℃ in an oxygen atmosphere (preferably a pure oxygen atmosphere), and then is calcined for 8-24 hours at 900-1200 ℃, so that the positive electrode active material is obtained. It can be understood that the positive electrode active material is also a layered structure based on the layered structure of the positive electrode precursor material.
A fourth aspect of the invention is to provide a positive electrode sheet comprising the positive electrode active material of the foregoing second aspect.
Specifically, the positive electrode sheet of the present invention includes a positive electrode current collector and a positive electrode active material attached to at least one surface of the positive electrode current collector, wherein the positive electrode active material includes at least the positive electrode active material of the foregoing second aspect, a conductive agent, and a binder.
In the preparation of the positive electrode, the positive electrode active material, the conductive agent, the binder and the solvent of the second aspect may be mixed to obtain a positive electrode slurry, the positive electrode slurry is disposed on at least one surface of the positive electrode current collector, and the solvent in the positive electrode slurry is volatilized to obtain the positive electrode sheet of the present invention.
The positive electrode of the present invention includes the positive electrode active material according to the second aspect, and therefore, when the positive electrode is used as a positive electrode of a secondary battery, the cycle performance and energy density of the secondary battery can be effectively improved.
A fifth aspect of the present invention is to provide a secondary battery whose positive electrode employs the positive electrode sheet of the fourth aspect.
The secondary battery of the present invention includes at least the negative electrode sheet, the electrolyte, and the positive electrode sheet of the fourth aspect. The secondary battery of the present invention includes the positive electrode sheet according to the fourth aspect, and therefore, when the secondary battery is used as a secondary positive electrode sheet, the cycle performance and energy density of the secondary battery can be effectively improved.
In one embodiment, the secondary battery is a sodium ion battery.
The positive electrode precursor material of the present invention will be described in detail below with reference to specific examples.
Example 1
The preparation method of the cathode precursor material of the embodiment includes the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a molar ratio of Ni to Mn to Fe of 0.8;
copper sulfate, ferrous sulfate and manganese sulfate crystals are dissolved to prepare a second mixed salt solution with a Cu-Fe-Mn molar ratio of 2;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding the first mixed salt solution into a reaction kettle with base solution (mixed solution of pure water and NaOH, the pH value is 10.5) at 65 ℃ at a feeding flow rate of 45L/h, a first precipitator solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99%) at a flow rate of 10mL/min, carrying out a first co-precipitation reaction, wherein the stirring linear speed in the reaction process is 300r/s, and feeding is stopped after 9 hours;
then, adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 30L/h and a second precipitator solution at a feeding flow rate of 10L/h, carrying out a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process, stopping feeding after 6 hours, and finishing the reaction; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ in the whole reaction process, and the pH value is 10.5;
3) Obtaining the positive electrode precursor material 0.6Ni by centrifugal washing (washing with deionized water till the pH of the washing liquid is 8 and the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.8 Mn 0.1 Fe 0.1 (OH) 2 *0.4Cu 0.2 Fe 0.3 Mn 0.5 CO 3 The Dv50 was 3.52. Mu.m.
Fig. 1 is a scanning electron micrograph of the positive electrode precursor material in example 1 of the present invention. As can be seen from fig. 1, the positive electrode precursor material of the present embodiment has a coated core-shell structure.
The positive electrode precursor material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.3 +/-0.05 mu m.
Example 2
The preparation method of the positive electrode precursor material of the embodiment comprises the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a molar ratio of Ni to Mn to Fe of 0.6;
dissolving copper sulfate, ferrous sulfate and manganese sulfate crystals to prepare a second mixed salt solution with a Cu: fe: mn molar ratio of 2;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding the first mixed salt solution into a reaction kettle with base solution (mixed solution of pure water and NaOH, the pH value is 10.2) at 65 ℃ at a feeding flow rate of 45L/h, a first precipitator solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99 percent) at a flow rate of 10mL/min, carrying out a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, and stopping feeding after 6 hours;
continuously adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 45L/h and a second precipitator solution at a feeding flow rate of 10L/h, carrying out a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process to obtain a precursor, stopping feeding after 6 hours, and finishing the reaction; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ in the whole reaction process, and the pH value is 10.2;
3) Obtaining the positive electrode precursor material 0.4Ni by centrifugal washing (washing with deionized water till the pH of the washing liquid is 8 and the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.6 Mn 0.2 Fe 0.2 (OH) 2 *0.6Cu 0.2 Fe 0.3 Mn 0.5 CO 3 And Dv50 is 3.35um.
The positive electrode precursor material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.5 +/-0.05 mu m.
Example 3
The preparation method of the cathode precursor material of the embodiment includes the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a Ni/Mn/Fe molar ratio of 0.4;
dissolving copper sulfate, ferrous sulfate and manganese sulfate crystals to prepare a second mixed salt solution with a Cu-Fe-Mn molar ratio of 1;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding first mixed salt at a feeding flow rate of 45L/h, a first precipitator solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (with the purity of 99.99%) at a flow rate of 10mL/min into a reaction kettle with a base solution (a mixed solution of pure water and NaOH, the pH value is 10.5) at 65 ℃ to perform a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, and feeding is stopped after 6 hours;
continuously adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 30L/h and a second precipitator solution at a feeding flow rate of 10L/h to perform a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process to obtain a precursor, and stopping feeding and finishing the reaction after 6 hours; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ and the pH value is 10.5 in the whole reaction process;
3) Obtaining the positive electrode precursor material 0.5Ni by centrifugal washing (washing with deionized water until the pH of the washing liquid is 8 and centrifuging until the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.4 Mn 0.3 Fe 0.3 (OH) 2 *0.5Cu 0.1 Fe 0.4 Mn 0.5 CO 3 And Dv50 was 3.5. Mu.m.
The positive electrode precursor material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.4 +/-0.05 mu m.
Example 4
The preparation method of the cathode precursor material of the embodiment includes the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a molar ratio of Ni to Mn to Fe of 0.4;
dissolving copper sulfate, ferrous sulfate and manganese sulfate crystals to prepare a second mixed salt solution with a Cu-Fe-Mn molar ratio of 1;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding first mixed salt at a feeding flow rate of 45L/h, a first precipitator solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (with the purity of 99.99%) at a flow rate of 10mL/min into a reaction kettle with a base solution (a mixed solution of pure water and NaOH, the pH value is 10.5) at 65 ℃ to perform a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, and feeding is stopped after 6 hours;
continuously adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 45L/h and a second precipitator solution at a feeding flow rate of 10L/h to perform a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process to obtain a precursor, and stopping feeding and finishing the reaction after 7 hours; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ in the whole reaction process, and the pH value is 10.5;
3) Obtaining the positive electrode precursor material 0.3Ni by centrifugal washing (washing with deionized water till the pH of the washing liquid is 8 and the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.4 Mn 0.3 Fe 0.3 (OH) 2 *0.7Cu 0.1 Fe 0.3 Mn 0.6 CO 3 And Dv50 is 3.51um.
The positive active material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.6 +/-0.05 mu m.
Example 5
The preparation method of the cathode precursor material of the embodiment includes the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a Ni/Mn/Fe molar ratio of 0.2 to 0.4, wherein the total metal concentration in the first mixed salt solution is 1mol/L, and adding citric acid (the concentration of the citric acid in the first mixed salt solution is 1 g/L) into the first mixed salt solution;
dissolving copper sulfate, ferrous sulfate and manganese sulfate crystals to prepare a second mixed salt solution with a Cu: fe: mn molar ratio of 3;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding first mixed salt into a reaction kettle with a base solution (a mixed solution of pure water and NaOH and with the pH of 10.5) at 65 ℃ at a feeding flow rate of 45L/h, a first precipitant solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99%) at a flow rate of 10mL/min, carrying out a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, and feeding is stopped after 6 hours;
continuously adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 30L/h and a second precipitator solution at a feeding flow rate of 10L/h, carrying out a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process to obtain a precursor, stopping feeding after 6 hours, and finishing the reaction; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ in the whole reaction process, and the pH value is 10.5;
3) Obtaining the positive electrode precursor material 0.5Ni by centrifugal washing (washing with deionized water until the pH of the washing liquid is 8 and centrifuging until the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.2 Mn 0.4 Fe 0.4 (OH) 2 *0.5Cu 0.3 Fe 0.3 Mn 0.4 CO 3 The Dv50 was 3.46. Mu.m.
The positive active material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.5 +/-0.15 mu m.
Example 6
The preparation method of the positive electrode precursor material of the present example is substantially the same as that of example 1, and the only difference is that the pH of the reaction process is maintained at 11, so as to obtain a positive electrode precursor material of 0.6Ni 0.8 Mn 0.1 Fe 0.1 (OH) 2 *0.4Cu 0.2 Fe 0.3 Mn 0.5 CO 3 The Dv50 was 2.64. Mu.m. The positive active material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.3 +/-0.1 mu m.
Example 7
The preparation method of the positive electrode precursor material of the present example is substantially the same as that of example 1, and the only difference is that the pH in the reaction process is maintained at 10, so as to obtain a positive electrode precursor material of 0.6Ni 0.8 Mn 0.1 Fe 0.1 (OH) 2 *0.4Cu 0.2 Fe 0.3 Mn 0.5 CO 3 The Dv50 was 4.82. Mu.m. The positive active material is observed and detected by a transmission electron microscope, and the thickness of the coating layer is 0.3 +/-0.05 mu m.
Comparative example 1
The preparation method of the positive electrode precursor material of this comparative example included the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a mixed salt solution with a molar ratio of Ni to Mn to Fe being 0.8; sodium hydroxide was prepared with pure water to give a 5mol/L aqueous solution of sodium hydroxide as a precipitant solution.
2) Respectively and jointly adding the mixed salt solution into a heating reaction kettle with base solution (mixed solution of pure water and NaOH, the pH value is 10.5) at 65 ℃ at a feeding flow rate of 45L/h, a precipitant solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99%) at a flow rate of 10mL/min, carrying out coprecipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, stopping feeding and finishing the reaction after 9 hours, and continuing stirring and aging for 2 hours after the reaction is finished;
the temperature of the system is maintained to be 65 ℃ and the pH value is 10.5 in the whole reaction process;
3) Obtaining a positive electrode precursor material Ni through centrifugal washing (washing by deionized water till the pH of the washing liquid is 8 and the washing liquid is centrifuged till the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.8 Mn 0.1 Fe 0.1 (OH) 2 The Dv50 was 3.14. Mu.m.
Fig. 2 is a scanning electron micrograph of the positive electrode precursor material in comparative example 1 of the present invention. As can be seen from fig. 2, the positive electrode precursor material in this comparative example has no coating layer.
Comparative example 2
The preparation method of the positive electrode precursor material of this comparative example included the following steps:
1) Dissolving nickel sulfate, ferrous sulfate and manganese sulfate crystals to prepare a first mixed salt solution with a Ni/Mn/Fe molar ratio of 0.8;
dissolving ferrous sulfate and manganese sulfate crystals to prepare a second mixed salt solution with the Fe/Mn molar ratio of 5, wherein the total metal concentration of the second mixed solution is 1.5mol/L, and adding 1g/L citric acid into the second mixed salt solution;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water to serve as a first precipitator solution, and preparing sodium carbonate into a sodium carbonate aqueous solution with the concentration of 3mol/L by using pure water to serve as a second precipitator solution;
2) Respectively and jointly adding the first mixed salt solution into a heating reaction kettle with a base solution (a mixed solution of pure water and NaOH and with the pH of 10.5) at 65 ℃ at a feeding flow rate of 45L/h, a first precipitant solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99%) at a flow rate of 10mL/min, carrying out a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, and feeding is stopped after 9 hours;
then, adding the second mixed salt solution into a reaction kettle with a first coprecipitation reaction system at a feeding flow rate of 30L/h and a second precipitator solution at a feeding flow rate of 10L/h, carrying out a second coprecipitation reaction, wherein the stirring linear speed is 200r/s in the reaction process, stopping feeding after 6 hours and finishing the reaction; after the reaction is finished, stirring and aging are continuously carried out for 2 hours;
the temperature of the system is maintained to be 65 ℃ and the pH value is 10.5 in the whole reaction process;
3) Obtaining the positive electrode precursor material 0.6Ni by centrifugal washing (washing with deionized water until the pH of the washing liquid is 8 and centrifuging until the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.8 Mn 0.1 Fe 0.1 (OH) 2 *0.4Fe 0.5 Mn 0.5 CO 3 。
Comparative example 3
The preparation method of the cathode precursor material of the embodiment includes the following steps:
1) Dissolving nickel sulfate, ferrous sulfate, manganese sulfate and copper sulfate crystals to prepare a mixed salt solution with a molar ratio of Ni, mn, fe and Cu of 0.6 to 0.1;
preparing sodium hydroxide into a sodium hydroxide aqueous solution with the concentration of 5mol/L by using pure water as a precipitator solution;
2) Respectively and jointly adding the mixed salt solution into a reaction kettle with a base solution (a mixed solution of pure water and NaOH, the pH value of the mixed solution is 10.5) at 65 ℃ at a feeding flow rate of 45L/h, a precipitant solution at a feeding flow rate of 60L/h, ammonia water (5 mol/L) at a feeding flow rate of 10mL/min and nitrogen (the purity is 99.99 percent) at a flow rate of 10mL/min, carrying out a first co-precipitation reaction, wherein the stirring linear speed is 300r/s in the reaction process, the feeding is stopped after 9 hours, and stirring and aging are continued for 2 hours after the reaction is finished;
the temperature of the system is maintained to be 65 ℃ and the pH value is 10.5 in the whole reaction process;
3) Obtaining a positive electrode precursor material Ni through centrifugal washing (washing by deionized water till the pH of the washing liquid is 8 and the washing liquid is centrifuged till the water content is below 15 percent) and drying treatment (100 ℃,24 h) 0.6 Mn 0.2 Fe 0.1 Cu 0.1 (OH) 2 。
Test example 1 detection of element content
The elemental content in the precursor of example 1 was tested using an inductively coupled plasma spectrometer (ICP).
Table 1 shows the results of element detection in example 1
Test example 2
Taking the precursor materials of the positive electrodes in the embodiments and the comparative examples, adding sodium carbonate according to the stoichiometric proportion of 110wt% of Na/(Ni + Fe + Mn + Cu), uniformly mixing the two materials in a high-speed mixer, keeping the temperature at 550 ℃ for 6 hours under the oxygen atmosphere, calcining at 1000 ℃ for 12 hours, and cooling to room temperature to obtain the active material of the positive electrode.
The positive electrode active material was tested as follows:
1. water content detection
The positive electrode active materials of the above examples and comparative examples were each subjected to a water content test using a karl fischer moisture tester, the cutoff temperature of which was set to 170 ℃. Placing the sample in a high vacuum oven at 100 ℃, performing nitrogen circulation once every 2 hours, and continuously drying for 12 hours to obtain a water content of 1 by detection; exposing the sample in the air for 2h, and detecting to obtain a water content of 2; the water content measured after exposing the sample to air for 24 hours was found to be test value 3. The test results are shown in Table 2.
2. Cycle performance and gram Capacity
The above-described positive electrode active materials obtained in the respective examples and comparative examples were mixed with conductive carbon black (Super P) and vinylidene fluoride (PVDF) in a mass ratio of 75:15:10 were slurried in a solution of N-methylpyrrolidone (NMP) and coated on aluminum foil, then cut into 12mm diameter pole pieces (loading about 3.0 + -0.5 mg/cm) 2 ) 1mol/L NaClO with a metal sodium sheet as a negative electrode 4 Polycarbonate (PC): ethylene Carbonate (EC): dimethyl carbonate (DMC) (volume ratio 1.
The following tests were carried out on the button half cells:
2-1 g capacity
And setting the voltage range to be 2.0-4.2V at 25 ℃, and carrying out charge and discharge tests on the assembled button cell at the multiplying power of 0.1C.
The gram capacity of the battery is calculated according to the following formula: gram capacity = first discharge capacity/mass of positive electrode active material.
2-2, capacity retention ratio
The voltage range of charging and discharging of the button cell is 2.0-4.2V, before the cycle test, a smaller current density 15mA/g (0.1C) is adopted for carrying out two times of activation, and then the cycle test is carried out at 25 ℃ by adopting 1C multiplying power in the same voltage range. Fig. 3 is a graph of the cycle performance of a sodium-ion battery of the present invention obtained from the positive electrode precursor material in example 1; fig. 4 is a graph showing the cycle performance of a sodium ion battery according to the present invention obtained from the positive electrode precursor material in comparative example 2.
TABLE 2
As can be seen from Table 2:
1. since the sample was not exposed to air before the test, the test value 1 was not greatly different between each example and comparative example; when the sample was exposed to air, the positive active materials of the examples according to the present invention had a significant water-absorbing inertness, as compared to comparative examples 1 to 3, and in particular, the advantage of the water-absorbing inertness of the positive active materials of the examples according to the present invention was more significant as the exposure time was prolonged. Therefore, the positive active material obtained by the precursor material has good air stability, and the cycle performance and gram capacity of a secondary battery comprising the positive active material can be improved;
2. in addition to the reason of good air stability, the specific elemental composition and the ratio between elements of the positive electrode precursor material allow the positive electrode active material to exhibit excellent energy density and cycle performance from the viewpoint of chemical performance.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The positive electrode precursor material is characterized in that the composition of the positive electrode precursor material is aNi 1-2x Mn x Fe x (OH) 2 ·bCu y Fe z Mn 1-y-z CO 3 ，a+b＝1,0.3≤a≤.8，0.2≤b≤0.7，0<X is less than or equal to 0.4, y is less than or equal to 0.1 and less than or equal to 0.4, and z is more than or equal to 0.2 and less than or equal to 0.5; wherein the content of the first and second substances,
the positive electrode precursor material comprises Ni 1-2x Mn x Fe x (OH) 2 Matrix particles and Cu y Fe z Mn 1-y-z A coating layer, at least a part of the surface of the base particle being covered with the coating layer.
2. The positive electrode precursor material according to claim 1, wherein the positive electrode precursor material is spherical particles or spheroidal particles.
3. The positive electrode precursor material according to claim 1 or 2, wherein the Dv50 of the positive electrode precursor material is 2.5 to 5 μm.
4. The positive electrode precursor material according to any one of claims 1 to 3, wherein the coating layer has a thickness of 0.2 to 1 μm.
5. The positive electrode precursor material according to any one of claims 2 to 4, wherein the matrix particles are spherical particles or spheroidal particles;
the base particle includes an inner core portion and an outer peripheral portion located at an outer periphery of the inner core portion, and a porosity of the inner core portion is smaller than a porosity of the outer peripheral portion.
6. A method for preparing a positive electrode precursor material according to any one of claims 1 to 5, characterized by comprising the steps of:
after a first mixed salt solution containing nickel salt, ferrous salt and manganese salt is subjected to a first coprecipitation reaction by using a first precipitator solution, respectively introducing a second mixed salt solution and a second precipitator solution into the system to perform a second coprecipitation reaction, thereby obtaining the anode precursor material;
the first precipitator solution is an aqueous solution containing hydroxyl, the second mixed salt solution contains copper salt, ferrous salt and manganese salt, and the second precipitator solution is a carbonate aqueous solution.
7. The method according to claim 6, wherein a reducing agent is contained in the reaction solution of the first coprecipitation reaction and the second coprecipitation reaction.
8. The method according to claim 6 or 7, wherein the reaction temperature in the first coprecipitation reaction and the second coprecipitation reaction is 55-70 ℃ and the pH value is 10-12.
9. The positive electrode active material is characterized in that the composition of the positive electrode active material is [ aNaNi ] 1-2x Mn x Fe x O 2 ]·[bNaCu y Fe z Mn 1-y-z O 2 ]，a+b＝1,0.3≤a≤0.8，0.2≤b≤0.7，0＜x≤0.4，0.1≤y≤0.4，0.2≤z≤0.5。
10. The positive electrode active material according to claim 9, wherein the positive electrode active material is obtained by a production method comprising:
the positive electrode active material is obtained by mixing and calcining the positive electrode precursor material according to any one of claims 1 to 5 with a sodium-containing compound.
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