CN116885197A - Positive electrode plate, preparation method thereof and sodium ion battery - Google Patents
Positive electrode plate, preparation method thereof and sodium ion battery Download PDFInfo
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- CN116885197A CN116885197A CN202311146971.2A CN202311146971A CN116885197A CN 116885197 A CN116885197 A CN 116885197A CN 202311146971 A CN202311146971 A CN 202311146971A CN 116885197 A CN116885197 A CN 116885197A
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- active material
- material layer
- positive electrode
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- transition metal
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- FKNQFGJONOIPTF-UHFFFAOYSA-N Sodium cation Chemical compound [Na+] FKNQFGJONOIPTF-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 229910001415 sodium ion Inorganic materials 0.000 title claims abstract description 19
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000011149 active material Substances 0.000 claims abstract description 69
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 32
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 31
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 31
- 229910000314 transition metal oxide Inorganic materials 0.000 claims abstract description 23
- 150000001875 compounds Chemical class 0.000 claims abstract description 21
- 229920000447 polyanionic polymer Polymers 0.000 claims abstract description 21
- 239000003792 electrolyte Substances 0.000 claims abstract description 16
- 239000002002 slurry Substances 0.000 claims description 66
- 239000011248 coating agent Substances 0.000 claims description 39
- 238000000576 coating method Methods 0.000 claims description 39
- 229910052782 aluminium Inorganic materials 0.000 claims description 17
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 17
- 239000011734 sodium Substances 0.000 claims description 17
- 239000011888 foil Substances 0.000 claims description 16
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 14
- 239000002033 PVDF binder Substances 0.000 claims description 14
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 14
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 claims description 12
- 235000011180 diphosphates Nutrition 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 239000000126 substance Substances 0.000 claims description 7
- 229910052723 transition metal Inorganic materials 0.000 claims description 7
- 150000003624 transition metals Chemical class 0.000 claims description 7
- 239000011230 binding agent Substances 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- 229910020691 Na4M3(PO4)2P2O7 Inorganic materials 0.000 claims description 3
- 229910019142 PO4 Inorganic materials 0.000 claims description 3
- 239000011889 copper foil Substances 0.000 claims description 3
- DWYMPOCYEZONEA-UHFFFAOYSA-L fluoridophosphate Chemical compound [O-]P([O-])(F)=O DWYMPOCYEZONEA-UHFFFAOYSA-L 0.000 claims description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 3
- 239000010452 phosphate Substances 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims 1
- 230000008901 benefit Effects 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 6
- 239000007774 positive electrode material Substances 0.000 abstract description 4
- 238000007086 side reaction Methods 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 57
- XWQGIDJIEPIQBD-UHFFFAOYSA-J sodium;iron(3+);phosphonato phosphate Chemical compound [Na+].[Fe+3].[O-]P([O-])(=O)OP([O-])([O-])=O XWQGIDJIEPIQBD-UHFFFAOYSA-J 0.000 description 28
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 19
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 235000019851 ferric sodium diphosphate Nutrition 0.000 description 15
- 239000011645 ferric sodium diphosphate Substances 0.000 description 15
- 239000011572 manganese Substances 0.000 description 13
- 239000003292 glue Substances 0.000 description 10
- 239000000203 mixture Substances 0.000 description 10
- 239000007787 solid Substances 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- 229940048084 pyrophosphate Drugs 0.000 description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 150000002500 ions Chemical class 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 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 2
- 239000010405 anode material Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- DCYOBGZUOMKFPA-UHFFFAOYSA-N iron(2+);iron(3+);octadecacyanide Chemical class [Fe+2].[Fe+2].[Fe+2].[Fe+3].[Fe+3].[Fe+3].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCYOBGZUOMKFPA-UHFFFAOYSA-N 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 229960003351 prussian blue Drugs 0.000 description 2
- 239000013225 prussian blue Substances 0.000 description 2
- 238000004513 sizing Methods 0.000 description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000006255 coating slurry Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 229910052744 lithium Inorganic materials 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
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- -1 polyethylene Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
- BYTVRGSKFNKHHE-UHFFFAOYSA-K sodium;[hydroxy(oxido)phosphoryl] phosphate;iron(2+) Chemical compound [Na+].[Fe+2].OP([O-])(=O)OP([O-])([O-])=O BYTVRGSKFNKHHE-UHFFFAOYSA-K 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a positive pole piece, a preparation method thereof and a sodium ion battery, and particularly relates to the technical field of sodium ion batteries. The positive electrode plate comprises a current collector, wherein a first active material layer and a second active material layer are sequentially laminated on at least one side surface of the current collector; the first active material layer comprises a transition metal oxide, conductive carbon black and carbon nanotubes; the second active material layer includes a polyanion-based compound, conductive carbon black, and carbon nanotubes. The positive electrode plate provided by the invention adopts a layering mode of two positive electrode materials, and adopts the transition metal oxide in the inner layer, so that the contact between the transition metal oxide and electrolyte is prevented, and meanwhile, the advantage of high capacity of the transition metal oxide is maintained; meanwhile, the outer layer material adopts polyanion compounds, so that side reactions with electrolyte are few, the performance is stable, and the cycle life of the sodium ion battery is prolonged.
Description
Technical Field
The invention relates to the technical field of sodium ion batteries, in particular to a positive electrode plate, a preparation method thereof and a sodium ion battery.
Background
The lithium ion secondary battery with high energy density is rapidly developed and widely applied to the fields of automobiles, aerospace, ships and the like, but the development of the lithium ion secondary battery is restricted due to the problems of high cost and low safety coefficient of the lithium ion secondary battery. The sodium ion secondary battery has the advantages of low cost, high safety coefficient, special application environment and the like, can be complementarily used with a lithium ion battery, and has excellent development prospect.
In the anode material of the lithium ion battery, metal cobalt is needed, and the resources are also deficient and the price is high. Na and Li belong to the same main group element, and the radius of Na is larger than that of Li. Therefore, the sodium battery is used as a more suitable substitute for the lithium ion battery, and the working principle is the same as that of the sodium battery. During charging, na + Removing the anode from the anode, entering an electrolyte, and embedding the electrolyte into the anode hard carbon through a separation film; upon discharge, na + The rocking chair battery is also called a rocking chair battery because the electrolyte is released from the negative electrode, passes through the separator, and is inserted into the positive electrode.
Sodium ion positive electrode materials are mainly of three types, including layered oxides, prussian blue and polyanion compounds. The nickel/iron/manganese layered oxide is most representative, has the advantages of higher capacity, and has the defects that the anode material is easy to react with electrolyte at an interface, so that the cycle life is poor. Prussian blue NaFeCN 6 The advantages of (2) are lower raw material cost, and the disadvantage is that the material contains crystal water, so that the cycle life is poor. The polyanion compound has the advantages of high material stability, less side reaction with electrolyte and good cycle life in the charge and discharge process; the disadvantage is the low specific energy.
In view of this, the present invention has been made.
Disclosure of Invention
The invention aims to provide a positive electrode plate so as to solve the technical problem that in the prior art, a layered oxide is easy to react with electrolyte at an interface to cause the deterioration of cycle life.
The second purpose of the invention is to provide a preparation method of the positive pole piece.
The third object of the present invention is to provide a sodium ion battery.
In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:
the invention provides a positive electrode plate, which comprises a current collector, wherein at least one side surface of the current collector is sequentially laminated with a first active material layer and a second active material layer.
The first active material layer includes a transition metal oxide, conductive carbon black, and carbon nanotubes.
The second active material layer includes a polyanion-based compound, conductive carbon black, and carbon nanotubes.
Further, in the first active material layer, the transition metal oxide accounts for 90wt.% to 98wt.%, the conductive carbon black accounts for 0.1wt.% to 5wt.%, and the carbon nanotube accounts for 0.1wt.% to 5wt.%.
In the second active material layer, the polyanion-based compound accounts for 90wt.% to 98wt.%, the conductive carbon black accounts for 0.1wt.% to 5wt.%, and the carbon nanotube accounts for 0.1wt.% to 5wt.%.
Further, in the first active material layer, the transition metal oxide accounts for 93wt.% to 96wt.%, the conductive carbon black accounts for 1.5wt.% to 4wt.%, and the carbon nanotube accounts for 1.5wt.% to 4wt.%.
In the second active material layer, the polyanion-based compound accounts for 93wt.% to 96wt.%, the conductive carbon black accounts for 1.5wt.% to 4wt.%, and the carbon nanotube accounts for 1.5wt.% to 4wt.%.
Further, the transition metal oxide is a transition metal layered oxide.
The polyanion compound comprises phosphate, fluorophosphate, pyrophosphate and mixed pyrophosphate.
Further, the polyanion compound is mixed pyrophosphate.
The chemical formula of the mixed pyrophosphate is Na 4 M 3 (PO 4 ) 2 P 2 O 7 M includes at least one of Fe, co, mn and Ni.
The chemical formula of the transition metal layered oxide is Na (Ni a Fe b Mn c )O 2 ；
Wherein 0 < a < 1,0 < b < 1,0 < c < 1, a+b+c=1.
Further, the current collector includes copper foil or aluminum foil.
The thickness of the current collector is 12 mu m-15 mu m.
The thickness of the positive pole piece is 70 mu m-200 mu m.
The second aspect of the present invention provides a method for preparing the positive electrode sheet, wherein the positive electrode sheet is obtained by coating the slurry of the first active material layer and the slurry of the second active material layer on at least one side surface of the current collector surface, and drying the slurry;
or (b)
And transferring the first active material layer and the second active material layer on at least one side surface of the current collector surface to obtain the positive electrode plate.
Further, the binder and the solvent are included in the slurry of the first active material layer and in the slurry of the first active material layer independently of each other.
The binder comprises polyvinylidene fluoride and the solvent comprises N-methylpyrrolidone.
Further, the slurry of the first active material layer had a coating surface density of 20g/m 2 -300g/m 2 。
The slurry of the second active material layer had a coating surface density of 20g/m 2 -300g/m 2 。
The third aspect of the invention provides a sodium ion battery, which comprises a negative electrode plate, a diaphragm, electrolyte and the positive electrode plate.
Compared with the prior art, the invention has at least the following beneficial effects:
the positive electrode plate provided by the invention adopts a layering mode of two positive electrode materials, and adopts the transition metal oxide in the inner layer, so that the contact between the transition metal oxide and electrolyte is prevented, and meanwhile, the advantage of high capacity of the transition metal oxide is maintained; meanwhile, the outer layer material adopts polyanion compounds, so that side reactions with electrolyte are few, the performance is stable, and the cycle life of the sodium ion battery is prolonged.
The preparation method provided by the invention has the advantages of continuous process, high degree of mechanization and strong controllability, and is suitable for large-scale industrial production.
The positive electrode plate with better service performance has the capacity retention rate of 87.96 percent after 1000 charge and discharge cycles, has good cycle stability, prolongs the service life of the sodium ion battery, and expands the service scene of the sodium ion battery and the development of downstream industry.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of a positive electrode sheet according to the present invention;
fig. 2 is a schematic structural view of another positive electrode sheet according to the present invention.
Icon: 100-current collector; 200-a first active material layer; 300-second active material layer.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to embodiments and examples, but it will be understood by those skilled in the art that the following embodiments and examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a positive electrode plate, which comprises a current collector, wherein at least one side surface of the current collector is sequentially laminated with a first active material layer and a second active material layer.
The first active material layer includes a transition metal oxide, conductive carbon black, and carbon nanotubes.
The second active material layer includes a polyanion-based compound, conductive carbon black, and carbon nanotubes.
The positive electrode plate provided by the invention adopts a layering mode of two positive electrode materials, and adopts the transition metal oxide in the inner layer, so that the contact between the transition metal oxide and electrolyte is prevented, and meanwhile, the advantage of high capacity of the transition metal oxide is maintained; meanwhile, the outer layer material adopts polyanion compounds, so that side reactions with electrolyte are few, the performance is stable, and the cycle life of the sodium ion battery is prolonged.
In some embodiments of the present invention, as shown in fig. 1, the positive electrode tab includes a current collector 100, first active material layers 200 positioned at both sides of the current collector 100, and second active material layers 300 positioned at a side of the first active material layers 200 remote from the current collector 100.
In other embodiments of the present invention, as shown in fig. 2, the positive electrode tab includes a current collector 100, a first active material layer 200 located at one side of the current collector 100, and a second active material layer 300 located at a side of the first active material layer 200 remote from the current collector 100.
The conductive carbon black is added into the first active material layer and the second active material layer to provide a conductive environment, so that the ion transmission efficiency is improved; the carbon nano tube forms an ion conductive network in the whole positive pole piece, so that the ion transmission efficiency is improved.
Further, in the first active material layer, the transition metal oxide accounts for 90wt.% to 98wt.%, the conductive carbon black accounts for 0.1wt.% to 5wt.%, and the carbon nanotube accounts for 0.1wt.% to 5wt.%.
In the second active material layer, the polyanion-based compound accounts for 90wt.% to 98wt.%, the conductive carbon black accounts for 0.1wt.% to 5wt.%, and the carbon nanotube accounts for 0.1wt.% to 5wt.%.
Further, in the first active material layer, the transition metal oxide accounts for 93wt.% to 96wt.%, the conductive carbon black accounts for 1.5wt.% to 4wt.%, and the carbon nanotube accounts for 1.5wt.% to 4wt.%.
In the second active material layer, the polyanion-based compound accounts for 93wt.% to 96wt.%, the conductive carbon black accounts for 1.5wt.% to 4wt.%, and the carbon nanotube accounts for 1.5wt.% to 4wt.%.
In the first active material layer, the ratio of the transition metal oxide is typically, but not limited to, 90wt.%, 91wt.%, 92wt.%, 93wt.%, 94wt.%, 95wt.%, 96wt.%, 97wt.%, or 98wt.%; the conductive carbon black is typically, but not limited to, 0.1wt.%, 0.5wt.%, 1wt.%, 1.5wt wt.%, 2wt.%, 3wt.%, 4wt.%, or 5wt.%; the carbon nanotube ratio is typically, but not limited to, 0.1wt.%, 0.5wt.%, 1wt.%, 1.5wt wt.%, 2wt.%, 3wt.%, 4wt.%, or 5wt.%.
Further, the transition metal oxide is a transition metal layered oxide, which is abbreviated as NFM.
The polyanion compound comprises phosphate, fluorophosphate, pyrophosphate and mixed pyrophosphate.
Further, the polyanion compound is mixed pyrophosphate.
The chemical formula of the mixed pyrophosphate is Na 4 M 3 (PO 4 ) 2 P 2 O 7 M includes at least one of Fe, co, mn and Ni.
The chemical formula of the transition metal layered oxide is Na (Ni a Fe b Mn c )O 2 ；
Wherein 0 < a < 1,0 < b < 1,0 < c < 1, a+b+c=1.
In some embodiments of the present invention, the chemical formula of the transition metal layered oxide is typically, but not limited to, na [ Ni ] 0.5 Mn 0.5 ]O 2 、Na[Ni 0.4 Mn 0.4 Fe 0.2 ]O 2 、Na[Ni 0.25 Mn 0.25 Fe 0.50 ]O 2 Or Na [ Ni ] 1/3 Mn 1/3 Co 1/3 ]O 2 。
Further, the current collector includes copper foil or aluminum foil.
The thickness of the current collector is 12 mu m-15 mu m.
The second aspect of the present invention provides a method for preparing the positive electrode sheet, wherein the positive electrode sheet is obtained by coating the slurry of the first active material layer and the slurry of the second active material layer on at least one side surface of the current collector surface, and drying the slurry;
or (b)
And transferring the first active material layer and the second active material layer on at least one side surface of the current collector surface to obtain the positive electrode plate.
The preparation method provided by the invention has the advantages of continuous process, high degree of mechanization and strong controllability, and is suitable for large-scale industrial production.
Further, the binder and the solvent are included in the slurry of the first active material layer and in the slurry of the first active material layer independently of each other. The adhesive can be used as a bridge for bonding between raw materials, so that the phenomenon that materials fall off from the pole pieces and powder falls off is prevented.
The binder comprises polyvinylidene fluoride (PVDF in english) and the solvent comprises N-methylpyrrolidone (NMP in english).
Further, the slurry of the first active material layer had a coating surface density of 20g/m 2 -300g/m 2 . When the coating surface density of the slurry of the first active material layer is lower than 20g/m 2 When the battery cell has lower overall capacity, namely lower energy density; when the slurry of the first active material layer has a coating surface density of more than 300g/m 2 And the cycle life benefit of the battery cell is poor. In some embodiments of the present invention, the slurry of the first active material layer typically has a coated surface density of, but not limited to, 50g/m 2 、100g/m 2 、150g/m 2 、200g/m 2 、250g/m 2 、300g/m 2 。
The slurry of the second active material layer had a coating surface density of 20g/m 2 -300g/m 2 . When the coating surface density of the slurry of the second active material layer is lower than 20g/m 2 When the battery cell is in a poor circulation performance; when the coating surface density of the slurry of the second active material layer is higher than 300g/m 2 When the battery cell is in a low overall capacity and low energy density. In some embodiments of the present invention, the slurry of the second active material layer typically has a coated surface density of, but not limited to, 50g/m 2 、100g/m 2 、150g/m 2 、200g/m 2 、250g/m 2 、300g/m 2 。
The third aspect of the invention provides a sodium ion battery, which comprises a negative electrode plate, a diaphragm, electrolyte and the positive electrode plate.
The positive electrode plate with better service performance has the capacity retention rate of 87.96 percent after 1000 charge and discharge cycles, has good cycle stability, prolongs the service life of the sodium ion battery, and expands the service scene of the sodium ion battery and the development of downstream industry.
The invention is further illustrated by the following specific examples and comparative examples, however, it should be understood that these examples are for the purpose of illustration only in greater detail and should not be construed as limiting the invention in any way. The raw materials used in the examples and comparative examples of the present invention were conducted under conventional conditions or conditions recommended by the manufacturer, without specifying the specific conditions. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. preparing NFM slurry: na [ Ni ] 1/3 Mn 1/3 Fe 1/3 ]O 2 94% of mass fraction, 2.5% of conductive carbon black and 0.5% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare an NFM slurry, wherein the solid content of the NFM slurry is equal to that of the NFM slurry46%.
2. Preparing sodium ferric pyrophosphate slurry: ferric sodium pyrophosphate (Na) 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) 94% of mass fraction, 2% of conductive carbon black and 1% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare ferric sodium pyrophosphate slurry, wherein the solid content of the ferric sodium pyrophosphate slurry is 46%.
3. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating NFM slurry on two sides of the aluminum foil, then coating ferric sodium pyrophosphate slurry on the surface of the NFM, and controlling the total coating quantity of 295g/m 2 The coating amount ratio was 54:46, obtaining the positive pole piece.
Example 2
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. preparing NFM slurry: taking Na [ Ni ] 1/3 Mn 1/3 Fe 1/3 ]O 2 98% of mass fraction, 0.1% of conductive carbon black and 0.9% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare an NFM slurry, wherein the solid content of the NFM slurry is 46%.
2. Preparing sodium ferric pyrophosphate slurry: taking ferric sodium pyrophosphate (Na) 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) 98% of mass fraction, 0.1% of conductive carbon black and 0.9% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare sodium ferric pyrophosphate slurry, wherein the solid content of the sodium ferric pyrophosphate slurry is 46%.
3. As in example 1.
Example 3
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. preparing NFM slurry: na [ Ni ] 1/3 Mn 1/3 Fe 1/3 ]O 2 96% of mass fraction, 2% of conductive carbon black and 1% of carbon nano tube, and adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare an NFM slurry, wherein the solid content of the NFM slurry is 46%.
2. Preparing sodium ferric pyrophosphate slurry: ferric sodium pyrophosphate (Na) 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) 96% by mass, 2% by mass of conductive carbon black and 1% by mass of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with a mass ratio of 613:26) to prepare ferric sodium pyrophosphate slurry, wherein the solid content of the ferric sodium pyrophosphate slurry is 46%.
3. As in example 1.
Example 4
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. preparing NFM slurry: na [ Ni ] 1/3 Mn 1/3 Fe 1/3 ]O 2 96% of mass fraction, 2% of conductive carbon black and 1% of carbon nano tube, and adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare an NFM slurry, wherein the solid content of the NFM slurry is 46%.
2. Preparing sodium ferric pyrophosphate slurry: ferric sodium pyrophosphate (Na) 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) 98% of mass fraction, 0.1% of conductive carbon black and 0.9% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare sodium ferric pyrophosphate slurry, wherein the solid content of the sodium ferric pyrophosphate slurry is 46%.
3. As in example 1.
Example 5
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. as in example 1.
2. As in example 2.
3. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating NFM slurry on two sides of the aluminum foil, then coating ferric sodium pyrophosphate slurry on the surface of the NFM, and controlling the total coating quantity of 295g/m 2 The coating amount ratio was 90: and 10, obtaining the positive pole piece.
Example 6
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. as in example 1.
2. As in example 2.
3. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating NF on two sides of the aluminum foilM sizing agent, then coating ferric sodium pyrophosphate sizing agent on the surface of NFM, controlling the total coating quantity to 295g/M 2 The coating amount ratio was controlled to be 10:90, obtaining the positive pole piece.
Example 7
The embodiment provides a positive pole piece, which is prepared by the following steps:
1. as in example 1.
2. As in example 2.
3. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating NFM slurry on two sides of the aluminum foil, then coating ferric sodium pyrophosphate slurry on the surface of the NFM, and controlling the total coating quantity of 295g/m 2 The coating amount ratio was 54:46, obtaining the positive pole piece.
Comparative example 1
The comparative example provides a positive electrode plate, which is prepared by the following steps:
1. preparing NFM slurry: na [ Ni ] 1/3 Mn 1/3 Fe 1/3 ]O 2 94% of mass fraction, 2.5% of conductive carbon black, 0.5% of carbon nano tube and adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare an NFM slurry, wherein the solid content of the NFM slurry is 46%.
2. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating NFM slurry on two sides of the aluminum foil, and controlling the density of a coating surface to be 160g/m 2 And (5) measuring the thickness of the coating after drying and cold pressing to obtain the positive pole piece.
Comparative example 2
The comparative example provides a positive electrode plate, which is prepared by the following steps:
1. preparing sodium ferric pyrophosphate slurry: ferric sodium pyrophosphate (Na) 4 Fe 3 (PO 4 ) 2 (P 2 O 7 ) 94% of mass fraction, 2% of conductive carbon black and 1% of carbon nano tube, adding a glue solution (NMP and PVDF blend solution with the mass ratio of 613:26) to prepare ferric sodium pyrophosphate slurry, wherein the solid content of the ferric sodium pyrophosphate slurry is 46%.
2. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, coating sodium ferric pyrophosphate slurry on two sides of the aluminum foil, and controlling the density of a coating surface to be 135g/m 2 Drying and coolingAnd measuring the thickness of the coating after pressing to obtain the positive pole piece.
Comparative example 3
The comparative example provides a positive electrode plate, which is prepared by the following steps:
1. as in example 1.
2. As in example 1.
3. In a drying room, taking an aluminum foil with the thickness of 13 mu m as a current collector, firstly coating sodium ferric pyrophosphate slurry on two sides of the aluminum foil, then coating NFM slurry on the surface of sodium ferric pyrophosphate, and controlling the total coating quantity of 295g/m 2 The coating amount ratio was 54:46, obtaining the positive pole piece.
Test example 1
The positive electrode sheets provided in examples 1 to 7 and comparative examples 1 to 3 were used as the negative electrode material, and fluoroethylene carbonate, ethylene carbonate, propylene carbonate, dimethyl carbonate and sodium salt NaPF were used as the electrolyte 6 The assembled battery was assembled by using the ceramic-coated polyethylene film as a separator, and the assembled battery was subjected to a charge-discharge cycle test after being left at 25 ℃ for 24 hours, and the results were shown in table 1 below.
TABLE 1
As is clear from Table 1, the present invention uses the inner layer to coat Na [ Ni ] in comparison with the single-layer coating slurry, the inner layer comprising sodium iron pyrophosphate and the outer layer comprising layered oxide 1/3 Mn 1/3 Fe 1/3 ]O 2 The layered oxide, when coated with sodium ferric pyrophosphate as the outer layer, shows a higher gram capacity and a longer cycle life.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. The positive electrode plate is characterized by comprising a current collector, wherein at least one side surface of the current collector is sequentially laminated with a first active material layer and a second active material layer;
the first active material layer comprises transition metal oxide, conductive carbon black and carbon nanotubes;
the second active material layer includes a polyanion-based compound, conductive carbon black, and carbon nanotubes.
2. The positive electrode sheet according to claim 1, wherein in the first active material layer, a transition metal oxide is 90wt.% to 98wt.%, a conductive carbon black is 0.1wt.% to 5wt.%, and a carbon nanotube is 0.1wt.% to 5wt.%;
in the second active material layer, the polyanion-based compound accounts for 90wt.% to 98wt.%, the conductive carbon black accounts for 0.1wt.% to 5wt.%, and the carbon nanotube accounts for 0.1wt.% to 5wt.%.
3. The positive electrode sheet according to claim 1, wherein in the first active material layer, a transition metal oxide is 93wt.% to 96wt.%, a conductive carbon black is 1.5wt.% to 4wt.%, and a carbon nanotube is 1.5wt.% to 4wt.%;
in the second active material layer, the polyanion-based compound accounts for 93wt.% to 96wt.%, the conductive carbon black accounts for 1.5wt.% to 4wt.%, and the carbon nanotube accounts for 1.5wt.% to 4wt.%.
4. A positive electrode sheet according to any one of claims 1 to 3, wherein the transition metal oxide is a transition metal layered oxide;
the polyanion compound comprises phosphate, fluorophosphate, pyrophosphate and mixed pyrophosphate.
5. The positive electrode sheet according to claim 4, wherein the polyanion-based compound is mixed pyrophosphate;
the chemical formula of the mixed pyrophosphate is Na 4 M 3 (PO 4 ) 2 P 2 O 7 M comprises at least one of Fe, co, mn and Ni;
the chemical formula of the transition metal layered oxide is Na (Ni a Fe b Mn c )O 2 ；
Wherein 0 < a < 1,0 < b < 1,0 < c < 1, a+b+c=1.
6. A positive electrode sheet according to any one of claims 1 to 3, wherein the current collector comprises copper foil or aluminum foil;
the thickness of the current collector is 12 mu m-15 mu m;
the thickness of the positive pole piece is 70 mu m-200 mu m.
7. A method for producing a positive electrode sheet according to any one of claims 1 to 6, characterized in that the positive electrode sheet is obtained by coating the slurry of the first active material layer and the slurry of the second active material layer on at least one side surface of the current collector surface, and drying;
or (b)
And transferring the first active material layer and the second active material layer on at least one side surface of the current collector surface to obtain the positive electrode plate.
8. The method according to claim 7, wherein the slurry of the first active material layer and the slurry of the first active material layer each independently further include a binder and a solvent;
the binder comprises polyvinylidene fluoride and the solvent comprises N-methylpyrrolidone.
9. The method according to claim 7, wherein the slurry of the first active material layer has a coating surface density of 20g/m 2 -300g/m 2 ；
The slurry of the second active material layer had a coating surface density of 20g/m 2 -300g/m 2 。
10. A sodium ion battery comprising a negative electrode sheet, a separator, an electrolyte, and the positive electrode sheet of any one of claims 1-6.
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| CN117154004A (en) * | 2023-10-31 | 2023-12-01 | 宁德时代新能源科技股份有限公司 | Positive electrode plate, battery and electricity utilization device |
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