CN116826032A - Doped sodium ion layered oxide positive electrode material and preparation method and application thereof - Google Patents
Doped sodium ion layered oxide positive electrode material and preparation method and application thereof Download PDFInfo
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- CN116826032A CN116826032A CN202310773648.1A CN202310773648A CN116826032A CN 116826032 A CN116826032 A CN 116826032A CN 202310773648 A CN202310773648 A CN 202310773648A CN 116826032 A CN116826032 A CN 116826032A
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- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 102
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 100
- 239000007774 positive electrode material Substances 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000011734 sodium Substances 0.000 claims abstract description 56
- 238000000034 method Methods 0.000 claims abstract description 28
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 15
- 239000010405 anode material Substances 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 8
- 230000000694 effects Effects 0.000 claims abstract description 6
- 229910052727 yttrium Inorganic materials 0.000 claims abstract description 6
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 5
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 37
- 239000002243 precursor Substances 0.000 claims description 23
- 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 22
- 229910052708 sodium Inorganic materials 0.000 claims description 22
- 238000002156 mixing Methods 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 16
- 229910052731 fluorine Inorganic materials 0.000 claims description 15
- 239000011737 fluorine Substances 0.000 claims description 15
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 14
- 229910052744 lithium Inorganic materials 0.000 claims description 14
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 9
- 238000001694 spray drying Methods 0.000 claims description 9
- 238000001556 precipitation Methods 0.000 claims description 7
- 238000010532 solid phase synthesis reaction Methods 0.000 claims description 5
- 238000000498 ball milling Methods 0.000 claims description 4
- 239000002002 slurry Substances 0.000 claims description 4
- 229910052726 zirconium Inorganic materials 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229910052725 zinc Inorganic materials 0.000 claims description 3
- 239000003513 alkali Substances 0.000 abstract description 16
- 229910052751 metal Inorganic materials 0.000 abstract description 16
- -1 oxygen ion Chemical class 0.000 abstract description 16
- 239000002184 metal Substances 0.000 abstract description 15
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052760 oxygen Inorganic materials 0.000 abstract description 7
- 239000001301 oxygen Substances 0.000 abstract description 7
- 230000002195 synergetic effect Effects 0.000 abstract description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 abstract description 3
- 239000011572 manganese Substances 0.000 description 44
- 230000000052 comparative effect Effects 0.000 description 25
- 239000010406 cathode material Substances 0.000 description 22
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 19
- 239000003792 electrolyte Substances 0.000 description 12
- 239000000243 solution Substances 0.000 description 12
- 238000012360 testing method Methods 0.000 description 12
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 10
- 239000010410 layer Substances 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000001035 drying Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 238000005303 weighing Methods 0.000 description 8
- 239000008139 complexing agent Substances 0.000 description 7
- 230000006872 improvement Effects 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 6
- 229910019398 NaPF6 Inorganic materials 0.000 description 6
- 239000002033 PVDF binder Substances 0.000 description 6
- 239000011230 binding agent Substances 0.000 description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 6
- 239000000047 product Substances 0.000 description 6
- 238000004537 pulping Methods 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000000975 co-precipitation Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000012086 standard solution Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 4
- URQWOSCGQKPJCM-UHFFFAOYSA-N [Mn].[Fe].[Ni] Chemical compound [Mn].[Fe].[Ni] URQWOSCGQKPJCM-UHFFFAOYSA-N 0.000 description 4
- 238000009616 inductively coupled plasma Methods 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- KJFMBFZCATUALV-UHFFFAOYSA-N phenolphthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2C(=O)O1 KJFMBFZCATUALV-UHFFFAOYSA-N 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 238000004448 titration Methods 0.000 description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 2
- 229910016036 BaF 2 Inorganic materials 0.000 description 2
- 229910004261 CaF 2 Inorganic materials 0.000 description 2
- FHKPLLOSJHHKNU-INIZCTEOSA-N [(3S)-3-[8-(1-ethyl-5-methylpyrazol-4-yl)-9-methylpurin-6-yl]oxypyrrolidin-1-yl]-(oxan-4-yl)methanone Chemical compound C(C)N1N=CC(=C1C)C=1N(C2=NC=NC(=C2N=1)O[C@@H]1CN(CC1)C(=O)C1CCOCC1)C FHKPLLOSJHHKNU-INIZCTEOSA-N 0.000 description 2
- 150000001450 anions Chemical class 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- CEQFOVLGLXCDCX-WUKNDPDISA-N methyl red Chemical compound C1=CC(N(C)C)=CC=C1\N=N\C1=CC=CC=C1C(O)=O CEQFOVLGLXCDCX-WUKNDPDISA-N 0.000 description 2
- 230000002572 peristaltic effect Effects 0.000 description 2
- 239000012266 salt solution Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 229910000029 sodium carbonate Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 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
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 1
- 238000002479 acid--base titration Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910001428 transition metal ion Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G53/00—Compounds of nickel
- C01G53/006—Compounds containing, besides nickel, two or more other elements, with the exception of oxygen or hydrogen
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- 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
- H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
-
- 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
- H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
- H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/40—Electric properties
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
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- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
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- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to a doped sodium ion layered oxide positive electrode material, a preparation method and application thereof. The chemical general formula of the doped sodium ion layered oxide anode material is as follows: na (Na) x Li 1‑x M 1‑y N y O 2‑z F 2z The method comprises the steps of carrying out a first treatment on the surface of the M is a transition metal element with electrochemical activity and is selected from at least two of Ni, fe, co, V, cr, mn, ti, cu; the N is an electrochemically inert elementOne or more selected from B, mg, zn, ca, al, zr, sn, Y, nb, sb, bi; x is more than or equal to 0.6<Y is more than 0 and less than or equal to 0.2, and z is more than 0 and less than or equal to 0.1. According to the invention, lithium element is doped in the sodium ion layer, inert element is doped in the active metal layer, fluorine ion is used for doping instead of oxygen ion, and the residual alkali content on the surface of the positive electrode material is effectively reduced under the condition that the energy density and the cycle performance of the positive electrode material are not reduced through the synergistic effect of the three elements.
Description
Technical Field
The invention relates to a doped sodium ion layered oxide positive electrode material, and a preparation method and application thereof, and belongs to the technical field of sodium ion battery positive electrode materials.
Background
With the vigorous development of renewable energy sources in recent years, the demand of energy storage devices is also increasing, and sodium ion batteries with the advantages of abundant resources, low price, high safety and the like are also attracting great attention. Among the sodium ion positive electrode materials which have been developed at present, the layered oxide has the advantages of high energy density, simple preparation method and the like, and is the sodium ion positive electrode material most likely to be industrialized first. However, the problems of high content of residual alkali on the surface, poor air stability and the like prevent the mass production process of the battery, and the existing solution method mainly comprises surface coating and multiple sintering, but all have the problems of low energy density, low production efficiency and the like of the battery.
Disclosure of Invention
The first object of the invention is to provide a doped sodium-ion layered oxide positive electrode material, which adopts a method of co-doping multiple elements, wherein lithium elements are doped in a sodium-ion layer, inert elements are doped in an active metal layer, fluorine ions are used for doping instead of oxygen ions, and the problem of high residual alkali content on the surface of the sodium-ion positive electrode material is effectively solved under the condition that the energy density and the cycle performance of the positive electrode material are not reduced by the synergistic effect of the three elements.
The second purpose of the invention is to provide a preparation method of the doped sodium ion layered oxide anode material, so as to solve the problem of high residual alkali content on the surface of the sodium ion anode material in the prior art.
The third purpose of the invention is to provide the application of the doped sodium ion layered oxide positive electrode material in the aspect of preparing the positive electrode of the sodium ion battery and/or the sodium ion battery, so as to solve the problem of high residual alkali content on the surface of the sodium ion positive electrode material in the prior art.
In order to achieve the above purpose, the technical scheme of the doped sodium ion layered oxide cathode material in the invention is as follows:
a doped sodium ion layered oxide cathode material, the doped sodium ion layered oxide cathode material having a chemical formula: na (Na) x Li 1-x M 1-y N y O 2-z F 2z The method comprises the steps of carrying out a first treatment on the surface of the M is a transition metal element with electrochemical activity and is selected from at least two of Ni, fe, co, V, cr, mn, ti, cu; the N is an electrochemical inert element and is selected from one or more of B, mg, zn, ca, al, zr, sn, Y, nb, sb, bi; x is more than or equal to 0.6<1，0＜y≤0.2，0＜z≤0.1。
The beneficial effects of the technical scheme are that: the invention discloses a doped sodium ion layered oxide positive electrode material, which uses a small amount of lithium ions to dope and replace sodium ions, can inhibit the sodium ions from being separated from the interlayer, and obviously reduces the residual alkali content on the surface of the positive electrode material; the transition metal ions with electrochemical activity are doped and replaced by using electrochemical inert element ions, so that the cycling stability of the material can be improved; the fluoride ion is used for carrying out anion doping substitution on oxygen ions, so that the structural stability of a layered anion frame can be improved, the redox reversibility of lattice oxygen can be enhanced, and the energy density of the material can be improved. The residual alkali content on the surface of the sodium ion positive electrode material is effectively reduced under the condition of not reducing the energy density and the cycle performance of the positive electrode material through the synergistic effect of the three.
Specifically, the average valence of M is alpha, and the value range of alpha is +2 to +4; the average valence of N is beta, and the value range of beta is +2 to +4; the relationship in the chemical formula satisfies alpha (1-y) +beta y=3.
As a further improvement, M is selected from three of Ni, fe and Mn, and x is more than or equal to 0.9 and less than or equal to 0.99; the N is selected from one or more of Zr, mg and Zn, and y is more than 0 and less than or equal to 0.12.
The beneficial effects of the technical scheme are that: the invention discloses a doped sodium ion layered oxide positive electrode material, wherein a transition metal layer mainly adopts three types of Ni, fe and Mn, and has electrochemical activity. The nickel-iron-manganese-based layered oxide is the sodium ion positive electrode material which is the most industrialized in the prior art and is consistent with the prior art by the industry and leading-edge researchers, but the nickel-iron-manganese-based layered oxide also faces the technical problems of high surface residual alkali and insufficient stability, and the application process of the material is affected. In order to solve the industry problem and accelerate the industry pace, the invention prefers the nickel-iron-manganese-based layered oxide as an optimization object. According to the invention, the structure of the material is regulated and controlled by introducing non-electrochemical active elements such as Zr, mg, zn and the like into the nickel-iron-manganese active metal layer, so that the structural change of the material during charge and discharge is stabilized, thus the irreversible capacity loss caused by structural collapse of the material is reduced, and meanwhile, the surface residual alkali of the material can be reduced by forming inert metal oxide on the surface. In addition, based on that the ionic radius of Zr, mg and Zn elements is closer to the ionic radius of Ni, fe and Mn of the active metal layer, the disorder of transition metal can be improved by introducing one of the three elements, so that the ionic mobility is improved, and the charge-discharge platform is more gentle.
Specifically, in the precursor containing M, ni is generally +2, fe is +2 or +3, mn is +2 or +3 in ionic valence state, and Ni is +2, fe is +3, mn is +4 in the obtained positive electrode material under high temperature oxygen-containing sintering conditions. Fe (Fe) 2+ Is oxidized to Fe 3+ 、Mn 2+/3+ Oxidized to Mn 4+ 、Ni 2+ Without any provision forThe change is mainly due to the valence balance in the material chemical formula being satisfied, and due to the reducing Fe 2+ ＞Mn 3+ ＞Ni 2+ Resulting in +2, which is more stable to sintering in environments other than pure oxygen, these inert metal elements exhibit a self-stable ionic valence state in the resulting material.
As a further improvement, the atomic ratio of Ni, fe and Mn is 2/9-1/3: 2/9-1/3: 2/9 to 1/3.
As a further improvement, the doped sodium ion layered oxide positive electrode material is selected from Na 0.9 Li 0.1 Ni 1/ 3 Fe 1/3 Mn 2/9 Zr 1/9 O 1.95 F 0.1 、Na 0.95 Li 0.05 Ni 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 1.95 F 0.1 、Na 0.98 Li 0.02 Ni 5/18 Fe 1/3 Mn 1/ 3 Zn 1/18 O 1.95 F 0.1 Any one of them.
In order to achieve the above purpose, the preparation method of the doped sodium ion layered oxide cathode material in the invention comprises the following steps:
a preparation method of a doped sodium ion layered oxide positive electrode material comprises the following steps: uniformly mixing a sodium source, a lithium source, a fluorine source, an M source and an N source, and performing heat treatment.
The beneficial effects of the technical scheme are that: the preparation method of the doped sodium ion layered oxide anode material has simple operation steps and is easy to popularize on a large scale.
As a further improvement, a solid phase method is adopted to prepare the doped sodium ion layered oxide anode material, the M source is oxide, and the mixing is ball milling mixing.
When preparing the doped sodium ion layered oxide positive electrode material by adopting a solid phase method, preferably, the sodium source is Na 2 CO 3 、NaHCO 3 And NaF, the feeding amount is 100-110% of the stoichiometric amount of sodium; the lithium source is Li 2 CO 3 At least one of LiOH and LiF, and feedingThe amount is 100 to 110 weight percent of the stoichiometric amount of lithium; the fluorine source is at least one of NaF and LiF, and the feeding amount is 100-110% of the stoichiometric amount of fluorine; the M source is oxide MO of at least two elements in Ni, fe, co, V, cr, mn, ti, cu b The method comprises the steps of carrying out a first treatment on the surface of the B is more than or equal to 1 and less than or equal to 2, and the feeding amount is the stoichiometric amount of M; the N source is oxide NO of one or more elements in B, mg, zn, ca, al, zr, ba, sn, Y, nb, sb, bi c The method comprises the steps of carrying out a first treatment on the surface of the C is more than or equal to 1 and less than or equal to 2; the dosage is the stoichiometric amount of N.
As a further improvement, the M source is M (OH) d Precursor materials, M (OH) prepared by precipitation d Precursor material, wherein d is more than or equal to 2 and less than or equal to 4.
Specifically, M salt mixed solution, complexing agent and precipitant are subjected to coprecipitation reaction in water to prepare M (OH) d The precursor material stops reacting when the sediment force D50 reaches 2-12 mu m. Wherein the M salt mixed solution is a sulfate or nitrate mixed solution of at least two elements in Ni, fe, co, V, cr, mn, ti, cu, and the total molar concentration of the M salt mixed solution is 1-2 mol/L; the complexing agent is one or more of ammonia water, sodium citrate and/or ethylenediamine tetraacetic acid, and the mass fraction of the complexing agent is 2% -10%; the precipitant is sodium hydroxide or potassium hydroxide solution, and the mass fraction of the precipitant is 20% -40%.
By M (OH) d When the precursor material is used for preparing the doped sodium ion layered oxide positive electrode material, preferably, the sodium source is Na 2 CO 3 、NaHCO 3 And NaF, the feeding amount is 100-110% of the stoichiometric amount of sodium; the lithium source is Li 2 CO 3 At least one of LiOH and LiF, wherein the feeding amount is 100-110% of the stoichiometric amount of lithium; the fluorine source is NaF, liF, mgF 2 、CaF 2 、BaF 2 At least one of the materials is 100-110 wt% of the stoichiometric amount of fluorine; wherein the actual feeding amount of sodium is Na 2 CO 3 、NaHCO 3 And NaF, the actual charge amount of lithium is Li 2 CO 3 The sum of LiOH and LiF; the N source is one or more elements in B, mg, zn, ca, al, zr, sn, Y, nb, sb, biOxide NO of element c The method comprises the steps of carrying out a first treatment on the surface of the C is more than or equal to 1 and less than or equal to 2; the dosage is the stoichiometric amount of N.
As a further improvement, the doped sodium ion layered oxide anode material is prepared by adopting a spray drying method, wherein M source is M (OH) d Precursor materials, M (OH) prepared by precipitation d Precursor material, wherein d is more than or equal to 2 and less than or equal to 4; the mixing is to prepare slurry containing sodium source, lithium source, fluorine source, M source, N source and solvent, and then spray drying is carried out.
Specifically, the spray drying treatment is carried out under the conditions that the feeding rate is 30-100mL/min, the induced air temperature is 100-250 ℃, the air outlet temperature is 80-120 ℃, and the rotating speed is 15000-27000rpm.
When preparing the doped sodium ion layered oxide positive electrode material by adopting a spray drying method, preferably, the sodium source is Na 2 CO 3 、NaHCO 3 And NaF, the feeding amount is 100-110% of the stoichiometric amount of sodium; the lithium source is Li 2 CO 3 At least one of LiOH and LiF, wherein the feeding amount is 100-110% of the stoichiometric amount of lithium; the fluorine source is NaF, liF, mgF 2 、CaF 2 、BaF 2 At least one of the materials is 100-110 wt% of the stoichiometric amount of fluorine; wherein the actual feeding amount of sodium is Na 2 CO 3 、NaHCO 3 And NaF, the actual charge amount of lithium is Li 2 CO 3 The sum of LiOH and LiF; the N source is an oxide or hydroxide of one or more elements in B, mg, zn, ca, al, zr, sn, Y, nb, sb, bi; the solvent is pure water and/or ethanol.
As a further improvement, the heat treatment condition is that the heat treatment is carried out for 10 to 24 hours in an air atmosphere at 800 to 1000 ℃.
The beneficial effects of the technical scheme are that: under the heat treatment condition, doping of various elements can be effectively realized, and the doped sodium ion layered oxide anode material is obtained.
Application of doped sodium ion layered oxide anode material in preparing sodium ion battery anode and/or sodium ion battery.
The beneficial effects of the technical scheme are that: experiments prove that the doped sodium ion layered oxide positive electrode material can effectively reduce the residual alkali content on the surface of the sodium ion positive electrode material under the condition of not reducing the energy density and the cycle performance of the positive electrode material.
Drawings
FIG. 1 is an XRD pattern of sodium ion positive electrode materials prepared in comparative examples 1 to 3 and examples 1 to 3 in experimental example 1 of the present invention.
Detailed Description
The present invention will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below. The equipment and materials used, etc., are commercially available or are conventional in the art. The methods in the following examples are conventional in the art unless otherwise specified.
1. Specific embodiment of doped sodium ion layered oxide positive electrode material and preparation method thereof
Example 1
The doped sodium-ion layered oxide cathode material Na of the embodiment 0.9 Li 0.1 Ni 1/3 Fe 1/3 Mn 2/9 Zr 1/ 9 O 1.95 F 0.1 The preparation method is a solid phase method, and the specific implementation operation is as follows:
step one, according to the mole ratio of 7.56:0.945:1.89:6:3:3:2 respectively weighing Na 2 CO 3 、Li 2 CO 3 、NaF、NiO、Fe 2 O 3 、Mn 2 O 3 With ZrO 2 ；
Step two, adopting a ball milling method to uniformly mix the weighed materials in the step one to obtain precursor powder;
step three, placing the precursor powder in a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 920 ℃;
step four: crushing and sieving the precursor powder after heat treatment to obtain doped sodium ion lamellarOxide positive electrode material Na 0.9 Li 0.1 Ni 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 1.95 F 0.1 。
Example 2
The doped sodium-ion layered oxide cathode material Na of the embodiment 0.95 Li 0.05 Ni 2/9 Fe 1/3 Mn 1/3 Mg 1/ 9 O 1.95 F 0.1 The preparation method is a precipitation method, and the specific implementation operation is as follows:
preparing a mixed sulfate solution of Ni, fe and Mn, wherein the molar ratio of the Ni, fe and Mn elements is 2:3:3, preparing ammonia water solution with the total molar concentration of 1.8mol/L and the mass fraction of 10 percent as a complexing agent, and preparing sodium hydroxide solution with the mass fraction of 20 percent as a precipitant;
continuously adding the mixed salt solution, the complexing agent and the precipitant prepared in the first step into pure water by using a peristaltic pump at flow rates of 30mL/min,12.9mL/min and 9mL/min respectively to perform coprecipitation reaction, keeping the pH value in the coprecipitation reaction process at 11.20, keeping the temperature at 60 ℃, keeping the rotating speed of a reaction kettle at 800rpm, and stopping feeding liquid when the granularity D50 of the precipitate reaches 5.5 mu m;
step three, washing the obtained precipitate with deionized water and drying to obtain Ni 2/8 Fe 3/8 Mn 3/8 (OH) 2 A precursor material;
step four, ni in the step three 2/8 Fe 3/8 Mn 3/8 (OH) 2 Precursor material and Na 2 CO 3 LiF, naF, mgO in a molar ratio of 16:8.505:0.945:0.945:2, uniformly mixing and then placing in a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 950 ℃;
step five, crushing the heat-treated material to obtain a doped sodium ion layered oxide anode material Na 0.95 Li 0.05 Ni 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 1.95 F 0.1 。
Example 3
The doped sodium of this exampleIon layered oxide positive electrode material Na 0.98 Li 0.02 Ni 5/18 Fe 1/3 Mn 1/3 Zn 1/ 18 O 1.95 F 0.1 The preparation method is a spray drying method, and the specific implementation operation is as follows:
preparing a mixed sulfate solution of Ni, fe and Mn, wherein the molar ratio of the Ni, fe and Mn elements is 5:6:6, preparing ammonia water solution with the total molar concentration of 1.8mol/L and the mass fraction of 10 percent as a complexing agent, and preparing sodium hydroxide solution with the mass fraction of 20 percent as a precipitant;
continuously adding the mixed salt solution, the complexing agent and the precipitant prepared in the first step into pure water by using a peristaltic pump at flow rates of 30mL/min,12.9mL/min and 9mL/min respectively to perform coprecipitation reaction, keeping the pH value in the coprecipitation reaction process at 11.20, keeping the temperature at 60 ℃, keeping the rotating speed of a reaction kettle at 800rpm, and stopping feeding liquid when the granularity D50 of the precipitate reaches 5.5 mu m;
step three, washing the obtained precipitate with deionized water and drying to obtain Ni 5/17 Fe 6/17 Mn 6/17 (OH) 2 A precursor material;
step four, ni as described in the examples 5/17 Fe 6/17 Mn 6/17 (OH) 2 Precursor material and Na 2 CO 3 LiF, naF, znO in the molar ratio of 17:8.505:0.378:1.512:1, respectively weighing;
step five, weighing the Na in the step four 2 CO 3 Adding LiF and NaF into pure water, stirring, wherein the rotation speed of a stirrer is kept at 900rpm, the stirring temperature is 40 ℃, and the stirring time is 30min;
step six, weighing Ni in the step four 5/17 Fe 6/17 Mn 6/17 (OH) 2 Adding MgO into the stirrer, and pre-dispersing for 2 hours to form slurry;
step seven, spray drying the slurry, wherein the feeding rate is 40mL/min, the induced air temperature is 190 ℃, the air outlet temperature is 100 ℃, and the rotating speed is 21000rpm;
step eight, placing the material subjected to spray drying in the step four into a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 950 ℃;
step nine, crushing the mixture after heat treatment to obtain a doped sodium ion layered oxide anode material Na 0.98 Li 0.02 Ni 5/18 Fe 1/3 Mn 1/3 Zn 1/18 O 1.95 F 0.1 。
2. Specific examples of applications of doped sodium ion layered oxide cathode materials in preparing sodium ion battery anodes and sodium ion batteries
Example 4
This example describes the doped sodium-ion layered oxide cathode material Na of example 1 0.9 Li 0.1 Ni 1/3 Fe 1/3 Mn 2/ 9 Zr 1/9 O 1.95 F 0.1 The positive plate is prepared, and the positive plate and the metal sodium negative electrode are assembled into a sodium ion battery, and the specific implementation operation is as follows:
positive electrode material Na prepared in example 1 0.9 Li 0.1 Ni 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 1.95 F 0.1 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone, pulping, smearing, drying and the like to obtain a positive plate containing a target product, and assembling the positive plate and a metal sodium negative electrode into the LIR2032 sodium ion battery, wherein GF/F is a battery diaphragm, and the electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC = 1:1:1Vol%with 2.0%FEC).
Example 5
This example describes the doped sodium-ion layered oxide cathode material Na of example 2 0.95 Li 0.05 Ni 2/9 Fe 1/ 3 Mn 1/3 Mg 1/9 O 1.95 F 0.1 The positive plate is prepared, and the positive plate and the metal sodium negative electrode are assembled into a sodium ion battery, and the specific implementation operation is as follows:
positive electrode material Na prepared in example 2 0.95 Li 0.05 Ni 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 1.95 F 0.1 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone, pulping, smearing, drying and the like to obtain a positive plate containing a target product, and assembling the positive plate and a metallic sodium negative electrode into the LIR2032 sodium ion battery, wherein GF/F is a battery diaphragm, and the electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC =1:1:1 vol%with2.0% FEC).
Example 6
This example describes the doped sodium-ion layered oxide cathode material Na of example 3 0.98 Li 0.02 Ni 5/18 Fe 1/ 3 Mn 1/3 Zn 1/18 O 1.95 F 0.1 The positive plate is prepared, and the positive plate and the metal sodium negative electrode are assembled into a sodium ion battery, and the specific implementation operation is as follows:
positive electrode material Na prepared in example 3 0.98 Li 0.02 Ni 5/18 Fe 1/3 Mn 1/3 Zn 1/18 O 1.95 F 0.1 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone, pulping, smearing, drying and the like to obtain a positive plate containing a target product, and assembling the positive plate and a metallic sodium negative electrode into the LIR2032 sodium ion battery, wherein GF/F is a battery diaphragm, and the electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC =1:1:1 vol%with2.0% FEC).
3. Comparative example
Comparative example 1
Doped sodium ion layered oxide cathode material NaNi of comparative example 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 2 Compared with the positive electrode material in the example 1, the preparation method is a solid phase method without doping of lithium ions and fluorine ions, and the specific implementation operation is as follows:
step one, according to the mol ratio of 9.45:6:3:2:2 respectively weighing Na 2 CO 3 、NiO、Fe 2 O 3 、Mn 2 O 3 With ZrO 2 ；
Step two, adopting a ball milling method to uniformly mix the weighed materials in the step one to obtain precursor powder;
step three, placing the precursor powder in a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 920 ℃;
step four: crushing and sieving the precursor powder after heat treatment to obtain a doped sodium ion layered oxide anode material NaNi 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 2 。
The positive electrode material NaNi prepared above is prepared 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 2 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone, pulping, smearing, drying and the like to obtain a positive plate containing a target product, and assembling the positive plate and a metal sodium negative electrode into the LIR2032 sodium ion battery, wherein GF/F is a battery diaphragm, and the electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC = 1:1:1Vol%with2.0% FEC).
Comparative example 2
Doped sodium ion layered oxide cathode material NaNi of comparative example 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 2 Compared with the positive electrode material in example 2, the preparation method is a precipitation method without doping of lithium ions and fluorine ions, and the specific implementation operation is as follows:
step one, na 2 CO 3 MgO and Ni as described in example 2 2/8 Fe 3/8 Mn 3/8 (OH) 2 Precursor materials were mixed in a molar ratio of 9.45:1:8, uniformly mixing and then placing in a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 950 ℃;
crushing the heat-treated material to obtain NaNi 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 2 Sodium ion layered oxide material.
The positive electrode material NaNi prepared above is prepared 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 2 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone,the positive plate containing the target product is obtained after the steps of pulping, smearing, drying and the like, and is assembled with a metal sodium negative electrode to form the LIR2032 sodium ion battery, GF/F is a battery diaphragm, and electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC = 1:1:1Vol%with2.0% FEC).
Comparative example 3
Sodium ion layered oxide cathode material NaNi of this comparative example 2/8 Fe 3/8 Mn 3/8 O 2 Compared with the positive electrode materials of examples 1 to 3, the preparation method is a precipitation method without doping lithium ions, fluorine ions and inert elements, and the specific implementation operation is as follows:
step one, na 2 CO 3 And Ni as described in example 2 2/8 Fe 3/8 Mn 3/8 (OH) 2 Precursor material was prepared in a molar ratio of 1.05:1, uniformly mixing and then placing in a muffle furnace, and performing heat treatment for 15 hours in an air atmosphere at 950 ℃;
crushing the heat-treated material to obtain NaNi 2/8 Fe 3/8 Mn 3/8 O 2 Sodium ion layered oxide material.
The positive electrode material NaNi prepared above is prepared 2/8 Fe 3/8 Mn 3/8 O 2 And Super P and a binder polyvinylidene fluoride according to the mass ratio of 90:5:5, mixing, adding solvent N-methyl pyrrolidone, pulping, smearing, drying and the like to obtain a positive plate containing a target product, and assembling the positive plate and a metal sodium negative electrode into the LIR2032 sodium ion battery, wherein GF/F is a battery diaphragm, and the electrolyte is sodium hexafluorophosphate electrolyte (1.0M NaPF6 in EC:DMC:EMC = 1:1:1Vol%with2.0% FEC).
4. Experimental example
Experimental example 1
The doped and undoped sodium ion layered oxide cathode material powders obtained in examples 1 to 3 and comparative examples 1 to 3 were subjected to an X-ray diffraction (XRD) pattern test to characterize crystal structures, and analyzed by using an inductively coupled plasma emission spectrometer (ICP) to test chemical components, and the test results are shown in fig. 1 and table 1, respectively.
From the XRD patterns of the respective preparation materials of fig. 1 and the mass percent results of the chemical element contents in the ICP of table 2, it can be seen that the sodium ion positive electrode materials prepared in comparative examples 1 to 3 and examples 1 to 3 are O3 type layered oxides containing the corresponding elements, and the mass ratio of the respective elements measured by the ICP test results within the error allowable range substantially coincides with the theoretical ratio of the chemical formula set.
TABLE 1 chemical compositions of sodium ion cathode materials prepared in comparative examples 1 to 3 and examples 1 to 3
Experimental example 2
The sodium ion batteries prepared in examples 4 to 6 and comparative examples 1 to 3 were subjected to charge and discharge tests with a test voltage window of 2.0 to 4.0V, a current density of 0.1 to 3C, a test temperature of 25℃, and 50 cycles at 0.5C, and test results shown in table 2.
Table 2 results of charge and discharge tests of sodium ion batteries prepared in examples 4 to 6 and comparative examples 1 to 3
| Sequence number | Gram Capacity for first week discharge (0.1C) | First effect | 1C gram capacity | 0.5C 50 week Capacity Retention Rate |
| Example 4 | 135mAh/g | 83％ | 122mAh/g | 96％ |
| Comparative example 1 | 131mAh/g | 80％ | 121mAh/g | 95％ |
| Example 5 | 132mAh/g | 88％ | 125mAh/g | 97％ |
| Comparative example 2 | 129mAh/g | 78％ | 120mAh/g | 96％ |
| Example 6 | 136mAh/g | 85％ | 126mAh/g | 97％ |
| Comparative example 3 | 124mAh/g | 75％ | 108mAh/g | 92％ |
As can be seen from table 2, compared with comparative example 3, the gram capacity and the 1C gram capacity are significantly improved in comparative examples 1 to 2, and the cycle stability of 0.5C cycle for 50 weeks is also significantly optimized; examples 4 to 6 were further improved in gram capacity at the first week and gram capacity at 1C, compared with comparative examples 1 to 2, and the cycle performance at 50 weeks of 0.5C was not much different, and the cycle performance was more stable. The comparison shows that the doped sodium ion layered oxide anode material not only does not reduce the energy density and the cycle performance of the anode material, but also is optimized and improved to a certain extent; meanwhile, the synergistic effect of doping lithium element in the sodium ion layer and doping inert element in the active metal layer and simultaneously using fluorine ion to substitute oxygen ions is more obvious than that of single-doped inert metal.
Experimental example 3
The doped and undoped sodium ion layered oxide cathode materials obtained in examples 1 to 3 and comparative examples 1 to 3 were vacuum-packed in a dehumidified (relative humidity < 10%) atmosphere for sampling (10 min or less (exposure time is for weighing sampling)), and then the surface residual alkali (OH) was measured by an acid-base titration method - And CO 3 2- ) The detection method is a surface lithium detection method, and the detailed operation is as follows:
1. principle of operation: titration of CO in cathode materials with hydrochloric acid standard solution 3 2- And OH (OH) - The sodium carbonate and sodium hydroxide contents were calculated by the volume of hydrochloric acid consumed.
2. Reagent:
hydrochloric acid: 0.1mol/L
Phenolphthalein: 10g/L
Methyl red ethanol solution: 1g/L
3. The operation process comprises the following steps:
(1) sample weighing: weighing 30+/-0.5 g of a sample (doped or undoped sodium ion layered oxide positive electrode material) in a 250mL iodine measuring bottle by using a balance, accurately measuring to 0.01g, and recording the weight m (g);
(2) stirring: adding 100mL of pure water into a measuring cylinder, adding a magnet, covering a cover, and placing on a magnetic stirrer to stir for 30 minutes;
(3) and (3) filtering: vacuum-filtering with 7cm microporous membrane;
(4) pipetting: firstly, rinsing 3 times with the filtrate, and transferring 2mL of the filtrate into a 100mL beaker (3 in parallel);
(5) titration: firstly, adding 2 drops of phenolphthalein indicator (solution turns red), titrating to colorless by using 0.1mol/L HCl standard solution, and recording the volume V of consumed hydrochloric acid standard solution 1 (mL); then, 5 drops of methyl red indicator (the solution turned yellow) were added, and the mixture was titrated to orange with 0.1mol/L HCl standard solution, and the orange-dropped filtrate was placed on a hot plate to boil the solution until the color turned yellow again. Cooling to room temperature, continuously titrating until reddish color is taken as an end point, and recording the volume V of hydrochloric acid solution consumed in the whole process 2 (mL)。
4. And (3) data processing:
Na 2 CO 3 ％＝(V 2 -V 1 )×C×73.886×100/1000m
NaOH％＝[V 2 -2×(V 2 -V 1 )]×C×23.946×100/1000m
wherein:
m-mass of sample, g;
concentration of the C-hydrochloric acid standard solution and mol/L;
105.987 molecular weight of sodium carbonate;
39.996 molecular weight of sodium hydroxide;
V 1 -a first titration endpoint;
V 2 -a second titration endpoint;
V 2 -V 1 :NaHCO 3 consuming the volume of hydrochloric acid (i.e. Na 2 CO 3 A second reaction step of (2);
2(V 2 -V 1 ):Na 2 CO 3 consuming the volume of hydrochloric acid;
V 2 -2(V 2 -V 1 ) NaOH consumes the volume of hydrochloric acid;
results are expressed in% (w/w) and should be retained to position 4 after the decimal point.
The residual alkali test results are shown in table 3. As is apparent from Table 3, the inert metal doped comparative examples 1 to 2 are compared with the undoped comparative example 3, OH - And CO 3 2- And the PH is reduced to some extent, but the reduction amplitude is not large; examples 1 to 3 compare comparative examples 1 to 2, OH - And CO 3 2- The pH is also significantly reduced. For example, the doped sodium ion layered oxide cathode material of example 1, OH, is compared to the doped sodium ion layered oxide cathode material of comparative example 1 - Reduced by 5.89%, CO 3 2- The pH was also reduced from 13.75 to 12.82 by 0.89%. Both the residual alkali and the pH test results of the doped sodium ion layered oxide cathode materials of examples 2-3 show a significant decrease, which two-way indicates that the invention is expected to solve the problem of high residual alkali content on the surface of the sodium ion cathode material.
Table 3 results of residual alkali test of layered oxide cathode materials of examples 1 to 3 and comparative examples 1 to 3
In summary, by adopting the method of co-doping multiple elements, the lithium element is doped in the sodium ion layer, the inert element is doped in the active metal layer, and meanwhile, fluorine ions are doped to replace oxygen ions, so that the problem of high residual alkali content on the surface of the sodium ion positive electrode material can be effectively solved under the condition of optimizing and improving the energy density and the cycle performance of the positive electrode material through the synergistic effect of the three elements.
The above description is only a preferred embodiment of the present invention, and the patent protection scope of the present invention is defined by the claims, and all equivalent structural changes made by the specification and the drawings of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A doped sodium ion layered oxide positive electrode material is characterized in that: the said blendingThe chemical general formula of the doped sodium ion layered oxide positive electrode material is as follows: na (Na) x Li 1-x M 1-y N y O 2-z F 2z The method comprises the steps of carrying out a first treatment on the surface of the M is a transition metal element with electrochemical activity and is selected from at least two of Ni, fe, co, V, cr, mn, ti, cu; the N is an electrochemical inert element and is selected from one or more of B, mg, zn, ca, al, zr, sn, Y, nb, sb, bi; x is more than or equal to 0.6<1，0＜y≤0.2，0＜z≤0.1。
2. The doped sodium ion layered oxide positive electrode material according to claim 1, characterized in that: the M is selected from three types of Ni, fe and Mn, and x is more than or equal to 0.9 and less than or equal to 0.99; the N is selected from one or more of Zr, mg and Zn, and y is more than 0 and less than or equal to 0.12.
3. The doped sodium ion layered oxide positive electrode material according to claim 2, characterized in that: the atomic ratio of Ni, fe and Mn is 2/9-1/3: 2/9-1/3: 2/9 to 1/3.
4. A doped sodium ion layered oxide positive electrode material according to any one of claims 1 to 3, characterized in that: the doped sodium ion layered oxide positive electrode material is selected from Na 0.9 Li 0.1 Ni 1/3 Fe 1/3 Mn 2/9 Zr 1/9 O 1.95 F 0.1 、Na 0.95 Li 0.05 Ni 2/9 Fe 1/3 Mn 1/3 Mg 1/9 O 1.95 F 0.1 、Na 0.98 Li 0.02 Ni 5/18 Fe 1/3 Mn 1/3 Zn 1/18 O 1.95 F 0.1 Any one of them.
5. A method for preparing the doped sodium ion layered oxide positive electrode material according to any one of claims 1 to 4, characterized in that: the method comprises the following steps: uniformly mixing a sodium source, a lithium source, a fluorine source, an M source and an N source, and performing heat treatment.
6. The method for preparing a doped sodium ion layered oxide positive electrode material according to claim 5, wherein: the doped sodium ion layered oxide anode material is prepared by adopting a solid phase method, wherein an M source is oxide, and the mixing is ball milling mixing.
7. The method for preparing a doped sodium ion layered oxide positive electrode material according to claim 5, wherein: m source is M (OH) d Precursor materials, M (OH) prepared by precipitation d Precursor material, wherein d is more than or equal to 2 and less than or equal to 4.
8. The method for preparing a doped sodium ion layered oxide positive electrode material according to claim 5, wherein: preparing a doped sodium ion layered oxide positive electrode material by adopting a spray drying method, wherein M source is M (OH) d Precursor materials, M (OH) prepared by precipitation d Precursor material, wherein d is more than or equal to 2 and less than or equal to 4; the mixing is to prepare slurry containing sodium source, lithium source, fluorine source, M source, N source and solvent, and then spray drying is carried out.
9. The method for producing a doped sodium ion layered oxide positive electrode material according to any one of claims 5 to 8, characterized in that: the heat treatment condition is that the heat treatment is carried out for 10 to 24 hours in an air atmosphere with the temperature of 800 to 1000 ℃.
10. Use of a doped sodium ion layered oxide positive electrode material according to any one of claims 1 to 4 for the preparation of a positive electrode for a sodium ion battery and/or a sodium ion battery.
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| CN118315583A (en) * | 2024-06-03 | 2024-07-09 | 中国科学技术大学 | Calcium-lithium co-doped sodium ion layered cathode material and preparation method and application thereof |
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|---|---|---|---|---|
| CN117133912A (en) * | 2023-10-26 | 2023-11-28 | 宁德时代新能源科技股份有限公司 | Sodium ion layered oxide positive electrode material, positive electrode plate, battery and electricity utilization device |
| CN118315583A (en) * | 2024-06-03 | 2024-07-09 | 中国科学技术大学 | Calcium-lithium co-doped sodium ion layered cathode material and preparation method and application thereof |
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