CN116544371A - Positive electrode material, sodium ion battery and electric equipment - Google Patents
Positive electrode material, sodium ion battery and electric equipment Download PDFInfo
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- CN116544371A CN116544371A CN202310467103.8A CN202310467103A CN116544371A CN 116544371 A CN116544371 A CN 116544371A CN 202310467103 A CN202310467103 A CN 202310467103A CN 116544371 A CN116544371 A CN 116544371A
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- Prior art keywords
- positive electrode
- electrode material
- sodium
- coating layer
- sodium salt
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- 239000007774 positive electrode material Substances 0.000 title claims abstract description 95
- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 73
- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 59
- 159000000000 sodium salts Chemical class 0.000 claims abstract description 58
- 239000011247 coating layer Substances 0.000 claims abstract description 52
- 229920000447 polyanionic polymer Polymers 0.000 claims abstract description 38
- 239000003575 carbonaceous material Substances 0.000 claims abstract description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 61
- 239000011734 sodium Substances 0.000 claims description 35
- 239000006258 conductive agent Substances 0.000 claims description 30
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 28
- 229910052799 carbon Inorganic materials 0.000 claims description 28
- 239000002041 carbon nanotube Substances 0.000 claims description 22
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 22
- 239000010410 layer Substances 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 9
- 239000013078 crystal Substances 0.000 claims description 8
- YPPMLCHGJUMYPZ-UHFFFAOYSA-L sodium;iron(2+);sulfate Chemical compound [Na+].[Fe+2].[O-]S([O-])(=O)=O YPPMLCHGJUMYPZ-UHFFFAOYSA-L 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 claims description 7
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 7
- 239000006230 acetylene black Substances 0.000 claims description 5
- 229910021389 graphene Inorganic materials 0.000 claims description 5
- OOIOHEBTXPTBBE-UHFFFAOYSA-N [Na].[Fe] Chemical compound [Na].[Fe] OOIOHEBTXPTBBE-UHFFFAOYSA-N 0.000 claims description 4
- XMWRBQBLMFGWIX-UHFFFAOYSA-N C60 fullerene Chemical class C12=C3C(C4=C56)=C7C8=C5C5=C9C%10=C6C6=C4C1=C1C4=C6C6=C%10C%10=C9C9=C%11C5=C8C5=C8C7=C3C3=C7C2=C1C1=C2C4=C6C4=C%10C6=C9C9=C%11C5=C5C8=C3C3=C7C1=C1C2=C4C6=C2C9=C5C3=C12 XMWRBQBLMFGWIX-UHFFFAOYSA-N 0.000 claims description 3
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 3
- 229910003472 fullerene Inorganic materials 0.000 claims description 3
- AWRQDLAZGAQUNZ-UHFFFAOYSA-K sodium;iron(2+);phosphate Chemical compound [Na+].[Fe+2].[O-]P([O-])([O-])=O AWRQDLAZGAQUNZ-UHFFFAOYSA-K 0.000 claims description 3
- 239000000853 adhesive Substances 0.000 abstract description 15
- 230000001070 adhesive effect Effects 0.000 abstract description 15
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 30
- 239000010405 anode material Substances 0.000 description 17
- 239000000463 material Substances 0.000 description 15
- 238000000498 ball milling Methods 0.000 description 14
- 239000003792 electrolyte Substances 0.000 description 13
- 239000000243 solution Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 12
- 239000011572 manganese Substances 0.000 description 12
- 239000002243 precursor Substances 0.000 description 12
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 9
- 238000000576 coating method Methods 0.000 description 9
- 238000001035 drying Methods 0.000 description 9
- 239000007787 solid Substances 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 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 description 7
- 229910052708 sodium Inorganic materials 0.000 description 7
- 239000002033 PVDF binder Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 229910021645 metal ion Inorganic materials 0.000 description 6
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000007599 discharging Methods 0.000 description 5
- 238000004090 dissolution Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229910004563 Na2Fe2 (SO4)3 Inorganic materials 0.000 description 4
- 241000080590 Niso Species 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 229910044991 metal oxide Inorganic materials 0.000 description 4
- 150000004706 metal oxides Chemical class 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000007773 negative electrode material Substances 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000010406 cathode material Substances 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000002002 slurry Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 238000012512 characterization method Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 239000011267 electrode slurry Substances 0.000 description 2
- 125000002573 ethenylidene group Chemical group [*]=C=C([H])[H] 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 229910021385 hard carbon Inorganic materials 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- -1 polytetrafluoroethylene Polymers 0.000 description 2
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 2
- 239000004810 polytetrafluoroethylene Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 229920001897 terpolymer Polymers 0.000 description 2
- 238000000991 transmission electron microscopy selected area electron diffraction Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229920006172 Tetrafluoroethylene propylene Polymers 0.000 description 1
- ZMVMBTZRIMAUPN-UHFFFAOYSA-H [Na+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Na+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O ZMVMBTZRIMAUPN-UHFFFAOYSA-H 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 1
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 238000010406 interfacial reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- RUTXIHLAWFEWGM-UHFFFAOYSA-H iron(3+) sulfate Chemical compound [Fe+3].[Fe+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O RUTXIHLAWFEWGM-UHFFFAOYSA-H 0.000 description 1
- 229910000360 iron(III) sulfate Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000004804 winding Methods 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
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- 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
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The embodiment of the invention provides a positive electrode material, a sodium ion battery and electric equipment, wherein the positive electrode material provided by the embodiment of the invention comprises an inner core and a coating layer arranged on the surface of the inner core, the inner core comprises a sodium ion layered oxide, and the coating layer contains polyanion sodium salt and a carbon material. In the embodiment of the invention, the layered positive electrode material is tightly coated by the coating layer containing the polyanion sodium salt and the carbon material, so that the problems that the interface impedance of the positive electrode material of the existing sodium ion battery is large and the positive electrode adhesive is easy to attack are solved.
Description
Technical Field
The invention relates to the technical field of sodium ion battery manufacturing, in particular to a positive electrode material, a sodium ion battery and electric equipment.
Background
Currently, sodium ion batteries are widely focused on because of the advantages of higher theoretical capacity, more sodium resources and the like of the layered oxide cathode material.
However, the interface impedance of the layered positive electrode material of the existing sodium ion battery is large, and the rate performance of the battery is poor; meanwhile, the layered positive electrode material has higher alkalinity, and alkaline groups attack positive electrode adhesives such as polyvinylidene fluoride during homogenate, so that slurry gel and processing are difficult.
Disclosure of Invention
The invention aims to solve the technical problems of large interface impedance of the anode material of the existing sodium ion battery and easiness in attacking an anode adhesive by providing the anode material, the sodium ion battery and electric equipment.
In order to solve the problems, the invention is realized by the following technical scheme:
the invention provides a positive electrode material, which comprises a core and a coating layer arranged on the surface of the core, wherein the core comprises a sodium ion layered oxide, and the coating layer contains polyanion sodium salt and a carbon material.
Further, in the positive electrode material, the polyanionic sodium salt includes polyanionic iron-based sodium salt and/or polyanionic vanadium-based sodium salt.
Further, in the positive electrode material, the polyanionic sodium iron-based salt includes one or more of sodium iron sulfate, sodium iron phosphate and sodium iron silicate.
Further, the polyanionic vanadium-based sodium salt includes Na 3 V 2 (PO 4 ) 3 And/or Na 7 V 4 (P 2 O 7 ) 4 PO 4 。
Further, in the positive electrode material, the chemical formula of the sodium iron sulfate is Na 2+2y Fe 2-y (SO 4 ) 3 In the formula, y is more than or equal to 0 and less than or equal to 0.5.
Further, in the positive electrode material, the coating layer contains a carbon-based conductive agent, and the carbon-based conductive agent comprises one or more of carbon nanotubes, acetylene black, graphene and fullerene.
Further, in the positive electrode material, the thickness of the coating layer is 20-100 nm;
and/or the mass ratio of the carbon-based conductive agent to the polyanion sodium salt in the coating layer is 2-10:100.
Further, in the positive electrode material, the crystal structure of the sodium ion layered oxide comprises a P2 type and O3 type mixed phase;
and/or the sodium ion layered oxide has a chemical formula of Na x MO 2 Wherein M is at least one selected from Fe, ni, li, cu, zn, co, ti, mn, and 0.90 is more than or equal to x is more than or equal to 0.70.
Further, in the positive electrode material, the pH of the positive electrode material is 8.5-9.5;
further, the Dv50 of the positive electrode material is 1 to 20 μm.
The invention also provides a sodium ion battery, which comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode material.
The invention also provides electric equipment, which comprises the sodium ion battery.
Compared with the prior art, the embodiment of the invention has the following advantages:
in the embodiment of the invention, the provided positive electrode material comprises an inner core and a coating layer arranged on the surface of the inner core, wherein the inner core comprises sodium ion layered oxide, and the coating layer contains polyanion sodium salt and carbon material. The coating layer tightly coats the layered positive electrode material, so that the contact interface between the layered positive electrode material and the electrolyte can be reduced, the dissolution of metal ions is relieved, and the cycle performance of the battery is improved; meanwhile, the carbon material in the coating layer reduces the interface reaction impedance of sodium ions, so that the multiplying power performance of the battery is optimized, the alkalinity of polyanion sodium salt in the coating layer is lower, the attack on a positive electrode adhesive can be reduced, the number of recyclable sodium ions in the battery can be effectively increased, and the first charge gram capacity of the battery is improved. Therefore, the positive electrode material provided by the embodiment of the invention solves the problems that the interface impedance of the positive electrode material of the existing sodium ion battery is large and the positive electrode adhesive is easy to attack.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
Fig. 1 is a schematic structural diagram of a positive electrode material of a sodium ion battery according to an embodiment of the present invention.
Reference numerals illustrate:
11-inner core, 12-cladding.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will become more readily apparent, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description.
The applicant of the invention finds that although the sodium ion battery has higher theoretical capacity and rated voltage, the interface impedance of the layered oxide positive electrode material is larger, the multiplying power performance of the battery is affected, and metal ions such as manganese are easily dissolved out under higher voltage, so that the cycle performance of the battery is reduced; meanwhile, the layered positive electrode material of the sodium ion battery has higher alkalinity, and alkaline groups attack positive electrode adhesives such as polyvinylidene fluoride during homogenate, so that slurry gel and processing are difficult.
In order to solve the above problems, the embodiment of the present invention provides a positive electrode material, as shown in fig. 1, which includes an inner core 11 and a coating layer 12 disposed on the surface of the inner core 11, wherein the inner core 11 includes a sodium ion layered oxide, and the coating layer 12 includes a polyanion type sodium salt and a carbon material.
The carbon material in the coating layer reduces interface reaction impedance of sodium ions, so that the rate performance of the battery is optimized; meanwhile, the polyanion sodium salt in the coating layer has lower alkalinity, so that the attack on the positive electrode adhesive can be reduced, the number of recyclable sodium ions in the battery can be increased, and the first charge gram capacity of the battery is improved. In addition, the layered positive electrode material is tightly coated by the coating layer, so that the contact interface between the layered positive electrode material and the electrolyte can be reduced, the dissolution of metal ions is relieved, and the cycle performance of the battery is improved.
In practical application, the anode material provided by the embodiment of the invention is subjected to TEM-SAED characterization, so that the surface material of the anode material has a crystal structure different from that of the internal layered oxide; meanwhile, the surface material is characterized by SEM EDS, the element components and the proportion of the carbon material and the polyanion sodium salt can be determined, and the existence of the polyanion sodium salt in the surface material can be determined by combining the TEM-SAED characterization with the crystal structure of the surface material.
Optionally, in an embodiment, the positive electrode material provided in the example of the present invention, the polyanionic sodium salt includes a polyanionic iron-based sodium salt and/or a polyanionic vanadium-based sodium salt. The polyanion-type iron-based sodium salt and the polyanion-type vanadium-based sodium salt have high sodium content and good contact performance with the carbon-based conductive agent, can effectively increase the quantity of recyclable sodium ions in the battery, and improves the first charge gram capacity of the battery.
Alternatively, in one embodiment, the polyanionic iron-based sodium salt described above includes sodium iron sulfate, sodium iron phosphate, or sodium iron silicate; the polyanionic vanadium-based sodium salt comprises Na 3 V 2 (PO 4 ) 3 Or Na (or) 7 V 4 (P 2 O 7 ) 4 PO 4 。
Wherein the chemical formula of the sodium iron sulfate is Na 2+2y Fe 2-y (SO 4 ) 3 In the formula, y is more than or equal to 0 and less than or equal to 0.5, higher sodium content and lower alkalinity can be ensured, the higher sodium content can effectively increase the quantity of recyclable sodium ions in the battery so as to improve the first charging gram capacity of the battery, and the lower alkalinity can reduce the attack of an internal layered positive electrode material on a positive electrode adhesive, so that the positive electrode sheet is convenient to process and form.
Optionally, in an embodiment, the coating layer further contains a carbon-based conductive agent, where the carbon-based conductive agent includes one or more of carbon nanotubes, acetylene black, graphene, and fullerene. The carbon-based conductive agent can effectively reduce the interface reaction impedance of sodium ions, so that the rate performance of the battery is optimized.
In the anode material provided by the embodiment of the invention, the coating layer is prepared by mixing the polyanion sodium salt and the carbon-based conductive agent, namely, the material of the coating layer is a mixture of the polyanion sodium salt and the carbon-based conductive agent, the mixture system can fully contact the polyanion sodium salt with the carbon-based conductive agent, and the conductivity of the polyanion sodium salt can be greatly improved, so that the advantages of low alkalinity and high sodium ion content of the polyanion sodium salt and the advantages of low interface impedance of the carbon-based conductive agent can be simultaneously exerted.
Wherein the polyanionic sodium salt and the carbon-based conductive agent may be uniformly or non-uniformly distributed in the coating layer. Under the condition that the polyanion sodium salt and the carbon-based conductive agent are uniformly mixed in the coating layer, the coating layer is prepared by uniformly mixing the polyanion sodium salt and the carbon-based conductive agent, and the performance advantages of the polyanion sodium salt and the carbon-based conductive agent can be fully exerted.
Alternatively, in one embodiment, the carbon-based conductive agent includes a one-dimensional carbon-based conductive agent.
Alternatively, in one embodiment, the one-dimensional carbon-based conductive agent includes carbon nanotubes.
Alternatively, in one embodiment, the thickness of the coating layer is 20 to 100nm.
In the embodiment of the invention, the applicant creatively discovers that the alkalinity of the formed anode material can not be effectively reduced when the thickness of the coating layer is smaller than 20 nm; when the thickness of the coating layer is larger than 100nm, the total energy density of the positive electrode material is easily reduced due to the fact that the ratio of the polyanion sodium salt is increased and the intrinsic capacity of the polyanion sodium salt is low.
In the actual preparation process, the thickness of the coating layer can be controlled within the above thickness range by adjusting the concentration difference of the sodium ion layered oxide as the core and the coating layer substance in the solution system. Wherein, when the concentration of the polyanion sodium salt and the carbon-based conductive agent as the coating material is increased and the concentration of the sodium ion layered oxide is decreased, the formed coating layer can be thickened.
Alternatively, in one embodiment, the pH of the positive electrode material is 8.5 to 9.5. In the embodiment of the invention, the alkalinity of the polyanion sodium salt is low, and the surface of the sodium ion layered oxide is coated with the coating layer formed by mixing the polyanion sodium salt and the carbon-based conductive agent, so that the pH value of the polyanion sodium salt can be controlled between 8.5 and 9.5, thereby effectively reducing the attack on the positive electrode adhesive.
Alternatively, in one embodiment, the cathode material has a Dv50 of 1 to 20 μm. In the embodiment of the invention, the applicant finds that when the Dv50 of the positive electrode material is smaller than 1 mu m, the surface activity is too high, so that the gas generation of the battery is easy to occur, and when the Dv50 is larger than 20 mu m, the migration path of sodium ions is too long, and the multiplying power performance of the battery is easy to be influenced. The Dv50 of the positive electrode material is preferably 5 μm to 12 μm, for example, 5 μm, 7 μm, 10 μm or 12 μm.
In the actual preparation process, the Dv50 of the positive electrode material can be adjusted to be 1-20 mu m by changing ball milling parameters. Specifically, the longer the ball milling time, the higher the rotational speed, the smaller the obtained positive electrode material Dv 50.
Optionally, in one embodiment, the mass ratio of the carbon-based conductive agent to the polyanionic sodium salt in the coating layer is 2-10:100.
In the embodiment of the invention, the applicant creatively discovers that when the mass ratio of the carbon-based conductive agent to the polyanion sodium salt in the coating layer is 2-10:100, the interface impedance of the formed anode material can be effectively reduced, and the multiplying power performance of the anode material can be improved.
Alternatively, in one embodiment, the crystal structure of the sodium ion layered oxide in the positive electrode material provided in the example of the present invention includes a P2 type and O3 type mixed phase.
The positive electrode material of the sodium ion battery can be classified into P2 type and O3 type due to the difference of crystal structures. The applicant found that the P2 type and O3 type mixed phase positive electrode material has the following problems, although it has the characteristics of high rated voltage and good cycle stability: the interface impedance is larger, and the multiplying power performance of the battery is poor; because the sodium content in the molecular formula of the P2 type and O3 type mixed phase positive electrode material is between 0.7 and 0.9, the available sodium ion quantity in the battery is low, and the initial efficiency of the battery is poor; metals such as Mn in the P2 type and O3 type mixed phase positive electrode material are easy to dissolve out by reacting with acid generated by side reaction, and the cycle performance of the battery is affected; the P2 type and O3 type mixed phase positive electrode material has higher alkalinity, and alkaline groups attack PVDF and the like during homogenate, so that slurry gel and processing are difficult.
In the embodiment of the invention, the P2 type and O3 type mixed phase sodium ion layered oxide is taken as an inner core, and the polyanion sodium salt and the carbon-based conductive agent are mixed and coated on the surface of the inner core to form the coating layer, so that the technical problems of the P2 type and O3 type mixed phase sodium ion layered oxide anode material can be effectively solved. Specifically, the interface reaction impedance of sodium ions is reduced by using the carbon-based conductive agent, so that the rate performance of the battery is optimized; meanwhile, the amount of recyclable sodium ions in the battery is increased by utilizing polyanion sodium salt in the coating layer, so that the first charge gram capacity of the battery is improved; in addition, the layered anode material is tightly coated with the P2 type and O3 type mixed phase sodium ion layered oxide by using the coating layer, so that the contact interface between the sodium ion layered oxide and the electrolyte can be reduced, and the dissolution of metal ions is relieved, thereby improving the cycle performance of the battery; and because the alkalinity of the polyanion sodium salt is lower, the P2 type and O3 type mixed phase sodium ion layered oxide is coated by the polyanion sodium salt, so that the attack on the positive electrode adhesive can be reduced, and the polyanion sodium salt is convenient to process and form a positive electrode plate.
Alternatively, in one embodiment, the sodium ion layered oxide provided in the examples of the present invention has the formula Na x MO 2 Wherein M is at least one selected from Fe, ni, li, cu, zn, co, ti, mn, and 0.90 is more than or equal to x is more than or equal to 0.70. Wherein, when x>0.9, the layered cathode material has a single O3 type crystal structure, and when x<And 0.7, the layered positive electrode material has a single P2 type crystal structure.
In practical applications, the P2 phase to O3 phase ratio can be adjusted by the sodium content x. The greater the x, the more the O3 phase is occupied and the smaller the x, the more the P2 phase is occupied.
Optionally, in a specific embodiment, the sodium ion layered oxide is formed by mixing P2 type and O3 type sodium ion layered metal oxides, wherein the space group of the O3 type sodium ion layered metal oxide is R-3m, and the molar ratio of the space group in the mixed phase is 20-98%; the space group of the P2 type sodium ion layered metal oxide is P63/mmc, and the mole ratio of the P2 type sodium ion layered metal oxide in the mixed phase is 2-80%.
The invention also provides a sodium ion battery, which comprises a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode active material layer arranged on the positive electrode current collector, and the positive electrode active material layer comprises the positive electrode material.
Optionally, in an embodiment, the positive electrode sheet further includes an adhesive, and the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic.
In some embodiments, the positive electrode sheet is prepared as follows: dispersing the components for preparing the positive electrode plate, such as the positive electrode active material comprising the positive electrode material, an adhesive and any other components, in solvents such as N-methylpyrrolidone and the like to form positive electrode slurry; coating positive electrode slurry on a positive electrode current collector; and drying, cold pressing and the like to obtain the positive pole piece.
The sodium ion battery provided by the embodiment of the invention further comprises a negative electrode plate, an isolating film and an electrolyte.
The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector, and the negative electrode active material layer may be a negative electrode active material for a battery, such as artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, or the like, which is known in the art.
Wherein the electrolyte plays a role of conducting ions between the positive electrode plate and the negative electrode plate, and the electrolyte can be liquid, gel state or all solid state. In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent, wherein the electrolyte salt is a sodium salt.
The embodiment of the invention also provides electric equipment, which comprises the sodium ion battery, wherein the sodium ion battery is used for providing power.
For the sodium ion battery embodiment and the electric device embodiment, the positive electrode plate includes a positive electrode active material layer, the positive electrode active material layer includes the positive electrode material, and the same technical effects can be achieved, so that repetition is avoided, and details are omitted herein, and the relevant parts are only needed to refer to part of the description of the positive electrode material embodiment.
In order to make the objects, technical solutions and advantageous effects of the present invention clearer, the present invention is further described below with reference to examples. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention.
Performance test method
(1) First charge gram capacity test:
connecting the manufactured battery with a test channel in a test cabinet, and charging to 3.0V at a multiplying power of 0.05C to perform formation to obtain formation gram capacity;
after the formation is finished, charging the battery to 3.8V at a multiplying power of 1C;
the sum of the two sections of charging capacity is the first charging gram capacity.
(2) Discharge rate performance test:
discharging the battery in a full-charge state to 1.5V at a current density of 0.33C in a room temperature environment, wherein the recording capacity is C1;
discharging the battery in a full-charge state to 1.5V at a current density of 5C in a room temperature environment, wherein the recording capacity is C2;
the capacity retention C2/C1 was calculated as a test index of discharge rate performance.
(3) And (3) testing the cycle performance: charging the battery to 3.8V at a current density of 1C under a room temperature environment, discharging to 1.5V at a current density of 1C, and recording the capacity C1 in the discharging process;
and (3) in a room temperature environment, charging the battery at a 1C multiplying power, discharging the battery at the 1C multiplying power, performing full charge discharge cycle test, wherein the voltage interval is 1.5-3.8V, stopping the test when the discharge capacity is gradually reduced to 80% C1, and recording the cycle number.
(4) And (3) testing the pH value of the positive electrode material:
5g of the sample was dissolved in 45mL of ethanol solution, and after stirring for 10min at 200r/min, the pH of the solution was measured.
Example 1
(1) Preparation of a positive electrode material:
a. at room temperature, according to n (Ni): n (Fe): n (Mn) =0.4: 0.2:0.4, niSO of a certain mass 4 ·6H 2 O、FeSO 4 ·7H 2 O and MnSO 4 ·H 2 Dissolving O in distilled water, stirring at 100rpm for 2 hr to form NiSO 4 、FeSO 4 MnSO 4 Mixed solutions with the concentration of 1mol/L, 0.5mol/L and 1mol/L respectively;
b. adding NaOH solid into the solution, controlling the concentration of NaOH to be 4mol/L, stirring for 12 hours at 200rpm, filtering the resultant, and drying to obtain precursor material Ni 0.4 Fe 0.2 Mn 0.4 (OH) 2 ；
c. According to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.8:1, placing the precursor material and NaOH solid into a ball mill, ball milling for 12 hours at a rotation speed of 300rpm, and pressing the powder precursor into a sheet shape, which is advantageous for uniform heating; then sintering the flaky precursor in an air environment at 800 ℃ for 12 hours, cooling and taking out to obtain a P2-O3 mixed phase anode material;
d. the positive electrode material was dissolved in 500mL of N-methylpyrrolidone (NMP) at a concentration of 1mol/L, and Na was added to the solution 2 SO 4 、FeSO 4 And carbon nanotubes, wherein Na 2 SO 4 Is 0.05mol/L, feSO 4 The concentration of (2) is 0.1mol/L, the addition amount of the carbon nano tube is 1g, and then the mixture is dried in vacuum in the stirring process at the temperature of 100 ℃ for 6 hours, so that Na 2 SO 4 、FeSO 4 Uniformly coating the carbon nano tube on the surface of the P2-O3 mixed phase anode material;
e. dryCalcining the resultant at 500 deg.C under Ar gas protection for 30 min after drying to obtain Na 2 SO 4 、FeSO 4 Reacting to form Na 2 Fe 2 (SO 4 ) 3 And coating the composite material and the carbon nano tube on the surface of the P2-O3 mixed phase anode material to obtain the anode material.
(2) Preparation of positive electrode plate
Mixing the prepared positive electrode material with PVDF and conductive carbon black according to a proportion of 85:7.5:7.5 mass ratio, and uniformly coating on the positive electrode current collector, wherein the surface density of the electrode plate is controlled to be 15mg/cm 2 And (3) drying at high temperature, rolling, cutting into pieces and slitting to prepare the positive pole piece.
(3) Preparation of negative electrode plate
The negative electrode material of hard carbon, styrene Butadiene Rubber (SBR), conductive carbon black and sodium carboxymethylcellulose (CMC) are mixed according to the proportion of 85:5.5:5.5:4, uniformly coating the mixture on a negative electrode current collector, and controlling the surface density of the electrode plate to be 8mg/cm 2 And (3) drying at high temperature, rolling, cutting into pieces and slitting to prepare the negative electrode plate.
(4) Preparation of sodium ion batteries
Taking polypropylene (PP) with thickness of 20um as a diaphragm, winding a positive electrode, a negative electrode and the diaphragm, and packaging, wherein the electrolyte is 1M NaClO 4 And (3) dissolving the solution in a Propylene Carbonate (PC) solvent to obtain the sodium ion battery.
Example 2
Example 2 differs from example 1 in that in step (c) according to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.85:1, and the precursor material and NaOH solids were placed in a ball mill.
Example 3
Example 3 differs from example 1 in that in step (c) according to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.75:1, and the precursor material and NaOH solids were placed in a ball mill.
Example 4
Example 4 differs from example 1 in that in step (c) according to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.6:1, and the precursor material and NaOH solid were placed in a ball mill.
Example 5
Example 5 differs from example 1 in that in step (c) according to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.9:1, and the precursor material and NaOH solids were placed in a ball mill.
Example 6
Example 6 differs from example 1 in that in step (c), the ball milling rotation speed was adjusted to 300rpm and the ball milling time was 18 hours.
Example 7
Example 7 differs from example 1 in that in step (c), the ball milling rotation speed was adjusted to 100rpm and the ball milling time was 12 hours.
Example 8
Example 8 differs from example 1 in that in step (c), the ball milling rotation speed was adjusted to 400rpm and the ball milling time was 18 hours.
Example 9
Example 9 differs from example 1 in that in step (c), the ball milling rotation speed was adjusted to 100rpm and the ball milling time was 1 hour.
Example 10
Example 10 differs from example 1 in that in step (d), the concentration of the P2-O3 mixed phase positive electrode material dissolved in 500 mLN-methylpyrrolidone (NMP) is adjusted to 4mol/L.
Example 11
Example 11 differs from example 1 in that in step (d), the concentration of the P2-O3 mixed phase positive electrode material dissolved in 500 mLN-methylpyrrolidone (NMP) is adjusted to 5mol/L.
Example 12
Example 12 differs from example 1 in that in step (d), the concentration of the P2-O3 mixed phase positive electrode material dissolved in 500 mLN-methylpyrrolidone (NMP) is adjusted to 0.8mol/L.
Example 13
Example 13 differs from example 1 in that in step (d), the concentration of the P2-O3 mixed phase positive electrode material dissolved in 500 mLN-methylpyrrolidone (NMP) is adjusted to 0.5mol/L.
Example 14
Example 14 differs from example 1 in that in step (d), na is adjusted 2 SO 4 Is 0.05mol/L, feSO 4 The concentration of (C) is 0.1mol/L, and the addition amount of the carbon nano tube is 0.4g.
Example 15
Example 15 differs from example 1 in that in step (d), na 2 SO 4 Is 0.05mol/L, feSO 4 The concentration of (C) is 0.1mol/L, and the addition amount of the carbon nano tube is 2g.
Example 16
Example 16 differs from example 1 in that in step (d), the substance added to the solution is adjusted to Na 3 V 2 (PO 4 ) 3 And carbon nanotubes, wherein Na 3 V 2 (PO 4 ) 3 The concentration of (C) is 0.05mol/L, and the addition amount of the carbon nano tube is 1g.
Example 17
Example 17 differs from example 1 in that in step (d), the carbon nanotubes are replaced with acetylene black.
Example 18
Embodiment 18 differs from embodiment 1 in that in step (d), the carbon nanotubes are replaced with graphene.
Comparative example 1
Comparative example 1 differs from example 1 in that steps (d) to (e) are omitted, and the prepared P2-O3 mixed phase positive electrode material is directly used to manufacture a positive electrode sheet.
Comparative example 2
Comparative example 2 differs from example 1 in that the positive electrode material was prepared as follows:
a. at room temperature, according to n (Ni): n (Fe): n (Mn) =0.4: 0.2:0.4, niSO of a certain mass 4 ·6H 2 O、FeSO 4 ·7H 2 O and MnSO 4 ·H 2 Dissolving O in distilled water, stirring at 100rpm for 2 hr to form NiSO 4 、FeSO 4 MnSO 4 Mixed solutions with the concentration of 1mol/L, 0.5mol/L and 1mol/L respectively;
b. in solution inAdding NaOH solid, controlling the concentration of NaOH to be 4mol/L, stirring for 12 hours at 200rpm, filtering the resultant, and drying to obtain precursor material Ni 0.4 Fe 0.2 Mn 0.4 (OH) 2 ；
c. According to n (Na): (n (Ni) +n (Fe) +n (Mn))=0.8:1, placing the precursor material and NaOH solid into a ball mill, ball milling for 12 hours at a rotation speed of 300rpm, and pressing the powder precursor into a sheet shape, which is advantageous for uniform heating; then sintering the flaky precursor in an air environment at 800 ℃ for 12 hours, cooling and taking out to obtain a P2-O3 mixed phase anode material;
d. the positive electrode material was dissolved in 500mL of N-methylpyrrolidone (NMP) at a concentration of 1mol/L, and Na was added to the solution 2 SO 4 、FeSO 4 Wherein Na is 2 SO 4 Is 0.05mol/L, feSO 4 The concentration of (2) is 0.1mol/L, and then vacuum drying is carried out in the stirring process, wherein the drying temperature is 100 ℃ and the time is 6 hours, so that Na 2 SO 4 、FeSO 4 Uniformly coating the surface of the P2-O3 mixed phase anode material;
e. calcining the product at 500 deg.C under Ar gas protection for 30 min after drying to obtain Na 2 SO 4 、FeSO 4 Reacting to form Na 2 Fe 2 (SO 4 ) 3 Coating the surface of the P2-O3 mixed phase anode material with Na 2 Fe 2 (SO 4 ) 3 The positive electrode material is dissolved in 500mL of N-methyl pyrrolidone (NMP) with the concentration of 1mol/L, and carbon nano tubes are added into the solution, wherein the addition amount of the carbon nano tubes is 1g, and then the solution is dried in vacuum in the stirring process, and the drying temperature is 100 ℃ for 6 hours, so that the carbon nano tubes are uniformly coated on Na 2 Fe 2 (SO 4 ) 3 A surface.
The P2 phase ratio, the thickness of the coating layer, the mass ratio of the carbon nanotubes to sodium iron sulfate in the coating layer, the pH value, and the particle Dv50 of the positive electrode materials in each example and comparative example were tested, and the test data are shown in table 1.
The batteries prepared in each example and comparative example were subjected to a first charge gram capacity test, a discharge rate performance test, and a cycle performance test, and the test data are shown in table 1.
TABLE 1
According to table 1, it is clear from comparative examples 1 to 18 and comparative examples 1 to 2 that by coating the surface of the sodium ion layered oxide of the mixed phase of P2 type and O3 type with a mixed layer of a polyanion sodium salt such as sodium ferric sulfate or sodium vanadium phosphate and a carbon-based conductive agent such as carbon nanotube, the pH of the positive electrode material can be reduced from 12.3 to 8.6 to 9.4 by utilizing the characteristic of low alkalinity of the polyanion sodium salt, and simultaneously, the interfacial reaction impedance of sodium ions can be reduced by utilizing the carbon-based conductive agent, thereby improving the rate capability; in addition, the layered positive electrode material is tightly coated by the coating layer, so that the contact interface between the layered positive electrode material and the electrolyte is reduced, and the dissolution of metal ions is relieved, thereby improving the cycle performance of the battery.
From table 1, it is known from comparative examples 1 to 5 that an increase in sodium ion content in the P2 type and O3 type mixed phases increases the pH of the positive electrode material, and increases the first charge gram capacity of the battery, increases the O3 phase ratio, and decreases the rate performance.
From table 1, it is understood that comparative examples 6 to 9 can adjust the Dv50 of the positive electrode material particles by controlling the rotation speed and the duration of the ball milling, and the higher the rotation speed of the ball milling, the longer the time, the smaller the Dv50 of the prepared positive electrode material particles, and the better the discharge rate performance of the prepared battery, but the smaller the Dv50, the greater the activity of the particles, the easier the particles react with the electrolyte, and the cycle performance is lowered.
According to table 1, comparative examples 10 to 13 show that the thickness of the coating layer can be adjusted by controlling the concentration of the P2-O3 mixed-phase sodium ion layered oxide in the reaction system, and the thicker the coating layer formed of the polyanion sodium salt and the carbon nanotube, the more the polyanion sodium salt is occupied, the sodium salt in the coating layer increases the number of recyclable sodium ions in the battery, the higher the first charge gram capacity of the battery is obtained by increasing the first charge gram capacity of the battery, and the less the interface of the alkaline P2-O3 mixed-phase sodium ion layered oxide core that can be exposed to the solution is, the lower the alkalinity is.
As is clear from comparative examples 1, 14 to 15 and 17 to 18, the use of carbon nanotubes as the conductive agent can further improve the discharge rate performance because the dispersibility of carbon nanotubes is good, a three-dimensional conductive network can be effectively formed, and acetylene black is a zero-dimensional conductive agent, which cannot be effectively formed. Graphene cannot be effectively dispersed between the main materials due to poor dispersion performance, and cannot effectively form a conductive network.
In summary, the provided positive electrode material provided in this embodiment includes a core and a coating layer disposed on a surface of the core, where the core includes a sodium ion layered oxide, and the coating layer contains a polyanion sodium salt and a carbon material. The coating layer tightly coats the layered positive electrode material, so that the contact interface between the layered positive electrode material and the electrolyte can be reduced, the dissolution of metal ions is relieved, and the cycle performance of the battery is improved; meanwhile, the carbon material in the coating layer reduces the interface reaction impedance of sodium ions, so that the multiplying power performance of the battery is optimized, the alkalinity of polyanion sodium salt in the coating layer is lower, the attack on a positive electrode adhesive can be reduced, the number of recyclable sodium ions in the battery can be effectively increased, and the first charge gram capacity of the battery is improved. Therefore, the positive electrode material provided by the embodiment of the invention solves the problems that the interface impedance of the positive electrode material of the existing sodium ion battery is large and the positive electrode adhesive is easy to attack.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including the preferred embodiment and all such alterations and modifications as fall within the scope of the embodiments of the invention.
The positive electrode material, the sodium ion battery and the electric equipment provided by the invention are described in detail, and specific examples are applied to illustrate the principle and the implementation mode of the invention, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (10)
1. The positive electrode material is characterized by comprising a core and a coating layer arranged on the surface of the core, wherein the core comprises a sodium ion layered oxide, and the coating layer contains polyanion sodium salt and a carbon material.
2. The positive electrode material according to claim 1, wherein the polyanionic sodium salt comprises a polyanionic iron-based sodium salt and/or a polyanionic vanadium-based sodium salt.
3. The positive electrode material according to claim 2, wherein the polyanionic iron-based sodium salt comprises one or more of sodium iron sulfate, sodium iron phosphate, sodium iron silicate;
and/or, the polyanionic vanadium-based sodium salt comprises Na 3 V 2 (PO 4 ) 3 And/or Na 7 V 4 (P 2 O 7 ) 4 PO 4 。
4. The positive electrode material according to claim 3, wherein the sodium iron sulfate has a chemical formula of Na 2+2y Fe 2-y (SO 4 ) 3 In the formula, y is more than or equal to 0 and less than or equal to 0.5.
5. The positive electrode material according to claim 1, wherein the coating layer contains a carbon-based conductive agent including one or more of carbon nanotubes, acetylene black, graphene, and fullerenes.
6. The positive electrode material according to claim 1, wherein the thickness of the coating layer is 20 to 100nm;
and/or the mass ratio of the carbon-based conductive agent to the polyanion sodium salt in the coating layer is 2-10:100.
7. The positive electrode material according to any one of claims 1 to 6, wherein the crystal structure of the sodium ion layered oxide includes a mixed phase of P2 type and O3 type;
and/or the sodium ion layered oxide has a chemical formula of Na x MO 2 Wherein M is at least one selected from Fe, ni, li, cu, zn, co, ti, mn, and 0.90 is more than or equal to x is more than or equal to 0.70.
8. The positive electrode material according to any one of claims 1 to 6, wherein the pH of the positive electrode material is 8.5 to 9.5;
and/or the Dv50 of the positive electrode material is 1-20 μm.
9. A sodium ion battery comprising a positive electrode sheet, characterized in that the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, the positive electrode active material layer comprising the positive electrode material of any one of claims 1 to 8.
10. A powered device comprising the sodium ion battery of claim 9.
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