CN119943945A - Positive electrode active material and preparation method, positive electrode sheet, sodium ion battery and device - Google Patents
Positive electrode active material and preparation method, positive electrode sheet, sodium ion battery and device Download PDFInfo
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Abstract
The application relates to an anode active material, a preparation method, an anode plate, a sodium ion battery and a device, wherein the anode active material comprises an active material body, and the general formula of the active material body is Na 4Fe3‑x‑yZrxMy(PO4)2(P2O7), wherein M is at least one of Ti, zn, V, mn, co and Al, and x is more than or equal to 0.01 and less than or equal to 0.05,0.01, and y is more than or equal to 0.05. The positive electrode active material increases lattice defects through Fe, zr and M metal ion co-doping, reduces lattice distortion, improves electron conductivity, finally enables the positive electrode active material to show excellent multiplying power performance and cycle stability under the condition of large multiplying power, and has the advantages of large capacity and high capacity retention rate.
Description
Technical Field
The application relates to the technical field of electrode materials, in particular to an anode active material, a preparation method thereof, an anode plate, a sodium ion battery and a device.
Background
Lithium ion batteries are widely applied to various aspects of daily life, however, due to the problems of lack of lithium resources and uneven distribution, people are forced to find alternative products of the lithium ion batteries, and the sodium ion batteries and the lithium ion batteries have similar working principles, are low in cost and easy to obtain raw materials, and are widely focused in recent years. Of the numerous sodium ion battery cathode materials, NACICON type cathode materials have excellent cycling stability, but have the problem of poor rate performance. Therefore, how to provide a sodium ion positive electrode material that can exhibit excellent rate performance under high rate conditions is a technical problem to be solved.
Disclosure of Invention
Based on this, it is necessary to provide a positive electrode active material capable of improving the rate performance, a method for producing the same, a positive electrode sheet, a sodium ion battery, and a device.
In one aspect of the present application, there is provided a positive electrode active material including an active material body having a general formula of Na 4Fe3-x-yZrxMy(PO4)2(P2O7), wherein M is at least one of Ti, zn, V, mn, co and Al, and x is 0.01.ltoreq. 0.05,0.01.ltoreq.y is 0.05.
The ion diffusion channel of the positive electrode active material in the charge and discharge process is increased by co-doping Fe, zr and M metal ions, carrier diffusion is promoted, the electron conductivity of the positive electrode active material is improved, and the co-doping of Fe, zr and M metal ions also increases lattice defects, reduces lattice distortion and inhibits phase change, so that the positive electrode active material is more beneficial to carrier embedding, and in the embedding and extraction process, the crystal structure is not easy to generate irreversible phase change or collapse, the circulation stability of the positive electrode active material is further improved, and finally the positive electrode active material shows excellent multiplying power performance and circulation stability under the condition of high multiplying power, and has the advantages of high capacity and high capacity retention rate.
In some embodiments, the positive electrode active material further comprises a carbon coating layer, wherein the carbon coating layer is arranged on the outer surface of the active material body, and the coating amount of C is 3% -5% of the mass of the positive electrode active material.
In some embodiments, M comprises at least one of Ti and Al.
In some of these embodiments, the general formula of the active material body includes at least one of Na4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7)、Na4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) and Na 4Fe2.93Zr0.02Co0.05(PO4)2(P2O7).
In some embodiments, the median particle diameter of the positive electrode active material is 3-7 μm.
In some embodiments, the positive electrode active material is in an orthorhombic system, pn2 1 a space group, and/or the positive electrode active material is in a bulk polycrystalline structure.
In a second aspect of the present application, there is provided a method for preparing the positive electrode active material according to the first aspect, comprising the steps of:
dissolving a sodium source, an iron source, a zirconium source, a metal M source, a phosphorus source and a complexing agent in a solvent according to the stoichiometric molar ratio of the anode active material, and carrying out blending treatment to obtain a mixed solution;
Drying the mixed solution to obtain mixed powder;
And sintering the mixed powder to obtain the positive electrode active material.
In some embodiments, the method for preparing the positive electrode active material satisfies at least one of the following:
(1) The sodium source comprises at least one of NaH 2PO4 and CH 3 COONa;
(2) The iron source includes at least one of Fe (NO 3)3、Fe(NO3)2 and FeC 2O4;
(3) The zirconium source includes Zr (at least one of NO 3)4 and Zr (CH 3COO)4;
(4) The complexing agent comprises at least one of citric acid and glucose, and/or the mole ratio of the complexing agent to metal ions in the positive electrode active material is 1.2-2:1;
(5) The metal M source is at least one of acetate, nitrate and oxide comprising metal M.
In some embodiments, the sintering process is performed at a temperature of 500 ℃ to 700 ℃.
In a third aspect of the present application, there is provided a positive electrode slurry comprising the positive electrode active material according to the first aspect and a positive electrode active material prepared by the preparation method according to the second aspect.
In some of these embodiments, the positive electrode slurry includes the positive electrode active material, a conductive agent, a binder, and a solvent.
In some embodiments, the positive electrode slurry satisfies at least one of the following conditions:
(1) The mass ratio of the positive electrode active material to the conductive agent to the binder is 8-9:0.25-1:0.25-1;
(2) The conductive agent comprises at least one of Super P, graphene, carbon dots, CNT and Ketjen black;
(3) The binder comprises at least one of vinylidene fluoride, polyvinylidene fluoride, and tetrafluoroethylene-hexafluoropropylene copolymer;
(4) The solid content of the positive electrode slurry is 50% -60%.
In a fourth aspect of the present application, there is provided a positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer, wherein the positive electrode active layer is provided on at least one side of the positive electrode current collector, and the positive electrode active layer comprises the positive electrode active material according to the first aspect, or is prepared from the positive electrode slurry according to the third aspect.
In some embodiments, the positive electrode sheet satisfies at least one of the following conditions:
(1) The thickness of the positive pole piece is 0.2 mm-0.6 mm;
(2) The single-sided surface density of the positive pole piece is 110g/m 2~160g/m2.
In a fifth aspect of the application, there is provided a sodium ion battery comprising the positive electrode sheet as described in the fourth aspect.
In a sixth aspect of the application there is provided an electrical device comprising a sodium ion battery as described in the fifth aspect.
Drawings
Fig. 1 is an electron microscopic view of the positive electrode active material prepared in example 1.
Fig. 2 is a charge-discharge curve at 0.2C of a metal sodium assembled half cell using the positive electrode active material of example 1.
Fig. 3 is a charge-discharge curve at 2C for a sodium ion battery cell employing the positive electrode active material of example 1.
Detailed Description
In order that the application may be readily understood, a more complete description of the application will be rendered by reference to the appended drawings. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The NASICON type positive electrode active material is a polyanion compound and has wide application prospect in sodium ion batteries. The positive electrode active material of NASICON commonly used at present comprises、、、AndAnd the like, the NASICON type positive electrode active materials have good cycling stability, but have the problem of poor rate performance due to poor electronic conductivity.
Based on this, in a first aspect of the present application, an embodiment provides a positive electrode active material including an active material body having a general formula of Na 4Fe3-x-yZrxMy(PO4)2(P2O7), wherein M is at least one of Ti, zn, V, mn, co and Al, and 0.01.ltoreq.x.ltoreq. 0.05,0.01.ltoreq.y.ltoreq.0.05.
The ion diffusion channel of the positive electrode active material in the charge and discharge process is increased by co-doping Fe, zr and M metal ions, carrier diffusion is promoted, the electron conductivity of the positive electrode active material is improved, and the co-doping of Fe, zr and M metal ions also increases lattice defects, reduces lattice distortion and inhibits phase change, so that the positive electrode active material is more beneficial to carrier embedding, and in the embedding and extraction process, the crystal structure is not easy to generate irreversible phase change or collapse, the circulation stability of the positive electrode active material is further improved, and finally the positive electrode active material shows excellent multiplying power performance and circulation stability under the condition of high multiplying power, and has the advantages of high capacity and high capacity retention rate.
The capacity of the positive electrode active material provided by the application for the metal sodium half-cell is 90 mAh/g-110 mAh/g under a voltage window of 2V-4V, the capacity retention rate of 1000 circles under a current density of 2C is 90% -96%, and the lattice distortion in the charge-discharge process is 7% -12%.
As an example, x may be 0.01, 0.02, 0.03, 0.04, or 0.05, or may be within a range formed by any two of the above-described dot values as end values. x is preferably 0.01 to 0.03.
As an example, y may be 0.01, 0.02, 0.03, 0.04, or 0.05, or may be in a range in which any two of the above-described dot values are used as end values. y is preferably 0.03 to 0.05.
In some embodiments, the positive electrode active material further comprises a carbon coating layer, wherein the carbon coating layer is arranged on the outer surface of the active material body, and the coating amount of C is 3% -5% of the mass of the positive electrode active material. The conductivity and structural stability of the positive electrode active material are improved by carbon coating, so that the electronic conductivity of the positive electrode active material is further improved.
Understandably, the positive electrode active material includes Na 4Fe3-x-yZrxMy(PO4)2(P2O7) and a carbon conductive layer coated on the outer surface thereof, and the carbon coating layer may cover a part of the outer surface of the active material body or may cover the entire outer surface of the active material body.
In some embodiments, M comprises at least one of Ti, zn, co, and Al.
In some embodiments, M comprises at least one of Ti and Al.
When the M metal is Ti, the energy band structure of the material can be changed by co-doping of Fe, zr and Ti, the energy band gap is adjusted by mainly changing the electron cloud distribution and oxidation state of atoms, and the defect energy level formed by doping Zr can be also intervened in the energy band gap, so that the energy band structure of the material can be adjusted more optimally by the combined action of three metal ions, the energy band distribution more favorable for electron conduction is formed, the energy barrier of electron transition is reduced, and the electron conductivity is further improved. And Fe, zr and Ti co-doping can optimize the crystal structure, reduce lattice distortion, improve the structural stability of the positive electrode active material and inhibit side reactions.
When the M metal is Al, different valence state changes of Fe can introduce some localized electron states in the energy band structure of the material, the doping of Zr can form a defect energy level, and the doping of Al can also generate similar defect energy levels due to the difference of atomic size and electron structure. The impurity energy levels co-introduced by the three ions of Fe, zr and Al interact to form a denser and more continuous electron transmission network inside the material, so that electrons can more smoothly transit and conduct in the material, thereby improving the electron conductivity. And Fe, zr and Al can optimize the crystal structure, reduce lattice distortion, reduce the resistance of ion migration in the positive electrode active material and improve the ion transmission environment.
Further, M includes Ti and Al. Fe. The co-doping of Zr, ti and Al can further reduce the energy barrier of electron transition and the resistance of ion migration, thereby further improving the electron conductivity of the positive electrode active material.
In some of these embodiments, the general formula of the active material body includes at least one of Na4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7)、Na4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) and Na4Fe2.93Zr0.02Co0.05(PO4)2(P2O7)、Na4Fe2.95Zr0.02Mn0.03(PO4)2(P2O7)、Na4Fe2.95Zr0.02Ti0.02Al0.01(PO4)2(P2O7)、Na4Fe2.94Zr0.01Zn0.02Ti0.03(PO4)2(P2O7)、Na4Fe2.95Zr0.01Zn0.01Mn0.03(PO4)2(P2O7) 、 Na4Fe2.93Zr0.02Zn0.03Co0.02(PO4)2(P2O7).
In some of these embodiments, the general formula of the active material body includes at least one of Na4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7)、Na4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) and Na 4Fe2.93Zr0.02Co0.05(PO4)2(P2O7).
In some of these embodiments, the general formula of the positive electrode active material includes at least one of Na4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7)@C、Na4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7)@C and Na4Fe2.93Zr0.02Co0.05(PO4)2(P2O7)@C、Na4Fe2.95Zr0.02Mn0.03(PO4)2(P2O7)@C、Na4Fe2.95Zr0.02Ti0.02Al0.01(PO4)2(P2O7)@C、Na4Fe2.94Zr0.01Zn0.02Ti0.03(PO4)2(P2O7) @C、Na4Fe2.95Zr0.01Zn0.01Mn0.03(PO4)2(P2O7)@C、 Na4Fe2.93Zr0.02Zn0.03Co0.02(PO4)2(P2O7) @C.
In some embodiments, the median particle diameter of the positive electrode active material is 3-7 μm. The method can shorten the diffusion path of sodium ions in the active positive electrode material under the median particle diameter, quicken the diffusion speed, and lead the charge and discharge efficiency of the battery to be higher, and the volume change of the positive electrode active material under the median particle diameter in the charge and discharge process is relatively uniform, and can reduce the particle breakage, pulverization and structural damage caused by volume expansion and shrinkage, thereby further improving the multiplying power performance and the circulation stability.
As an example, the median particle diameter of the positive electrode active material may be 3 μm, 3.5 μm, 4 μm, 4.5 μm,5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, or may be in a range in which any two of the above-mentioned dot values are used as the end values. The median particle diameter of the positive electrode active material is preferably 6-7 mu m.
In some of these embodiments, the positive electrode active material is an orthorhombic system, pn2 1 a space group.
In some of these embodiments, the positive electrode active material has a bulk polycrystalline structure.
In a second aspect of the present application, there is provided a method for preparing the positive electrode active material according to the first aspect, comprising the steps of:
dissolving a sodium source, an iron source, a zirconium source, a metal M source, a phosphorus source and a complexing agent in a solvent according to the stoichiometric molar ratio of the anode active material, and carrying out blending treatment to obtain a mixed solution;
And drying the mixed solution to obtain mixed powder.
And sintering the mixed powder to obtain the positive electrode active material.
In some embodiments, the sodium source, the iron source, the zirconium source, the metal M source, the phosphorus source and the carbon source are dissolved in a solvent according to the stoichiometric molar ratio of the positive electrode active material to be subjected to blending treatment, so as to prepare a mixed solution. Namely, the outer surface of the active material body is coated with a carbon coating layer.
Further, the carbon source includes at least one of citric acid and sucrose.
In some embodiments, the sodium source comprises at least one of NaH 2PO4 and CH 3 COONa.
In some of these embodiments, the iron source comprises Fe (at least one of NO 3)3、Fe(NO3)2 and FeC 2O4).
In some of these embodiments, the zirconium source comprises Zr (at least one of NO 3)4 and Zr (CH 3COO)4).
In some embodiments, the complexing agent comprises at least one of citric acid and glucose.
In some embodiments, the molar ratio of the complexing agent to the metal ions in the positive electrode active material is 1.2-2:1.
In some embodiments, the metal M source is at least one of an acetate, nitrate, and oxide comprising metal M.
In some of these embodiments, the phosphorus source comprises a phosphate.
Further, the phosphorus source is sodium phosphate.
In some embodiments, the solvent is deionized water or ethanol.
In some embodiments, the drying process employs a spray dryer for spray drying.
In some embodiments, the sintering process is a high temperature sintering at a temperature of 500 ℃ to 700 ℃ under a protective gas condition.
In a third aspect of the present application, there is provided a positive electrode slurry comprising the positive electrode active material according to the first aspect and a positive electrode active material prepared by the preparation method according to the second aspect.
In some of these embodiments, the positive electrode slurry includes the positive electrode active material, a conductive agent, a binder, and a solvent.
In some embodiments, the mass ratio of the positive electrode active material, the conductive agent and the binder is 8-9:0.25-1:0.25-1. The electron conductivity and structural stability of the positive electrode active material are further improved at this ratio.
The mass ratio of the positive electrode active material to the conductive agent to the binder is preferably 8.5-9:0.25-0.6:0.25-0.6.
In some embodiments, the conductive agent includes at least one of Super P, graphene, carbon dots, CNT, and ketjen black.
In some of these embodiments, the binder comprises at least one of vinylidene fluoride, polyvinylidene fluoride, and tetrafluoroethylene-hexafluoropropylene copolymer.
In some embodiments, the solid content of the positive electrode slurry is 50% -60%.
The application also provides a conductive coating, the components of which comprise the positive electrode active material, the conductive agent and the binder according to the first aspect, or the conductive coating is prepared from the positive electrode slurry according to the third aspect.
In a fourth aspect of the present application, there is provided a positive electrode sheet comprising a positive electrode current collector and a positive electrode active layer, wherein the positive electrode active layer is provided on at least one side of the positive electrode current collector, and the positive electrode active layer comprises the positive electrode active material according to the first aspect, or is prepared from the positive electrode slurry according to the third aspect.
In some embodiments, the preparation process of the positive electrode plate comprises the steps of uniformly coating positive electrode slurry on at least one side of a positive electrode current collector, and drying to form a positive electrode active layer to prepare the positive electrode plate.
In some of these embodiments, the positive current collector employs aluminum foil.
In some embodiments, the thickness of the positive electrode plate is 0.2 mm-0.6 mm. The thickness of the positive electrode plate is the overall thickness of the positive electrode active layer and the positive electrode current collector. Preferably 0.2mm to 0.4mm.
In some of these embodiments, the positive electrode active layer has a single-sided areal density of 110g/m 2~160g/m2.
In a fifth aspect of the application, there is provided a sodium ion battery comprising the positive electrode sheet as described in the fourth aspect.
The ion diffusion channel of the positive electrode active material in the charge and discharge process is increased by co-doping Fe, zr and M metal ions, sodium ion diffusion is promoted, the electron conductivity of the positive electrode active material is improved, and the co-doping of Fe, zr and M metal ions also increases lattice defects, reduces lattice distortion, inhibits phase transition, so that the positive electrode active material is more beneficial to sodium ion intercalation, the crystal structure is not easy to generate irreversible phase transition or collapse in the sodium ion intercalation and deintercalation process, and the circulation stability of the positive electrode active material is improved, and meanwhile, the conductivity and the structural stability of the positive electrode active material are improved by carbon coating, so that the electron conductivity of the positive electrode active material is further improved, and finally, the sodium ion battery shows excellent multiplying power performance and circulation stability under the condition of high multiplying power and has the advantages of high capacity and high capacity retention rate.
In some embodiments, the sodium ion battery comprises a positive electrode sheet, a negative electrode sheet, a diaphragm and electrolyte, wherein the positive electrode sheet and the negative electrode sheet are arranged opposite to each other, and the diaphragm is positioned between the positive electrode sheet and the negative electrode sheet.
In some of these embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode active layer disposed on at least one side of the negative electrode current collector.
In some of these embodiments, the negative electrode current collector is an aluminum plastic film.
The preparation process of the negative electrode plate comprises the steps of uniformly coating the negative electrode slurry on at least one side of a negative electrode current collector, and drying to form a negative electrode active layer to prepare the negative electrode plate.
In some of these embodiments, the anode active layer includes an anode active material, a conductive agent, a binder, and a thickener.
In some of these embodiments, the negative electrode active material is a carbon-based active material.
Further, the anode active material is hard carbon.
In some of these embodiments, the conductive agent is at least one of conductive carbon black, CNT, carbon dots, graphene, and ketjen black.
In some of these embodiments, the binder is at least one of vinylidene fluoride, polyvinylidene fluoride, and styrene butadiene rubber.
In some of these embodiments, the thickener is carboxymethyl cellulose.
In some embodiments, the mass ratio of the negative electrode active material, the conductive agent, the binder and the thickener in the negative electrode slurry is 8.5-9.5:0.25-0.4:0.1-0.4.
In some embodiments, the solid content of the negative electrode slurry is 30% -50%.
In some of these embodiments, the negative electrode active layer has a single-sided areal density of 40 g/m 2~80g/m2. And selecting proper negative electrode surface density to enable the N/P ratio of the battery cell to be 1:1.05-1.09.
In some of these embodiments, the separator is at least one of a fiberglass separator, a PE separator, a PP separator, a single-sided alumina coated PP separator, a double-sided alumina coated PP separator.
In some embodiments, the electrolyte is 1M-1.5M NaPF 6 or NaClO 4 solution.
In some of these embodiments, the solvent employed for the electrolyte comprises at least one of EC, DEC, DMC, EMC and DME.
In some embodiments, FEC with the mass content of 2% -5% is added into the electrolyte as an electrolyte additive.
In a sixth aspect of the application there is provided an electrical device comprising a sodium ion battery as described in the sixth aspect.
The power utilization device includes, but is not limited to, a wristwatch, a wireless headset, a digital product, a smart card, a remote control, an automobile part, and an electronic product.
The following are specific examples.
Example 1
Example 1 provides a positive electrode active material having the general formula Na 4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7) @ C, i.e., an active material body Na 4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7) provided with a carbon coating layer on the outer surface.
The positive electrode active material of example 1 was prepared as follows:
Weighing sodium phosphate, ferric nitrate, zirconium oxide and titanium oxide according to a stoichiometric ratio, dissolving the sodium phosphate, the ferric nitrate and the zirconium oxide in deionized water, preparing a suspension, taking citric acid as a carbon source and a complexing agent at the same time, adding the citric acid into the suspension according to a molar ratio of 1.55:1, stirring for 0.5h, transferring to a spray dryer for spray drying, wherein the inlet temperature of the spray drying is 110-120 ℃, the outlet temperature is 80-90 ℃, obtaining yellow powder, collecting and grinding, and calcining for 10h at 550 ℃ in a mixed atmosphere of hydrogen and argon (the mixture of hydrogen with the mass content of 5% and argon with the mass content of 95%) to obtain a positive electrode active material Na 4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7 @C, wherein the positive electrode active material is black powder, and the median particle size is 5 mu m.
The preparation method of the positive electrode sheet of example 1 is as follows:
Weighing a positive electrode active material, a conductive agent Super P and a binder PVDF (polyvinylidene fluoride) according to the mass ratio of 8:1:1, wherein the PVDF is prepared into an NMP solution (N-methylpyrrolidone) of PVDF with the mass fraction of 4% in advance, mixing the positive electrode active material, the Super P and the PVDF, adding NMP to ensure that the solid content of the slurry is 45%, preparing positive electrode slurry, uniformly coating the positive electrode slurry on an aluminum foil, and drying and cold pressing to obtain a positive electrode plate, wherein the surface density is 115g/m 2.
Example 2
Example 2 provides a positive electrode active material having the general formula Na 4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) @ C, i.e., an active material body Na 4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) provided with a carbon coating layer on the outer surface.
The preparation method of the positive electrode active material of example 2 is basically the same as that of example 1, except that zinc acetate is used as a zinc source, sucrose is used as a carbon source, and the addition amount of sucrose is 3% of the mass of the theoretical positive electrode active material, and the molar ratio of citric acid to metal ions is 1.2:1.
The positive electrode active material was in the form of black powder, and the median particle diameter was 7. Mu.m.
The preparation method of the positive electrode sheet of example 2 is basically the same as that of example 1, except that the mass ratio of the positive electrode active material, the conductive agent and the binder is 9:0.5:0.5, and the conductive agent is ketjen black.
Example 3
Example 3 provides a positive electrode active material having the general formula Na 4Fe2.93Zr0.02Co0.05(PO4)2(P2O7) @ C, i.e., an active material body Na 4Fe2.93Zr0.02Co0.05(PO4)2(P2O7) @ C, the outer surface of which is provided with a carbon coating layer.
The preparation method of the positive electrode active material of example 3 is basically the same as that of example 1, except that cobalt acetate is used as the cobalt source and the calcination temperature is 600 ℃.
The positive electrode active material was in the form of black powder, and the median particle diameter was 5. Mu.m.
The preparation method of the positive electrode sheet of example 3 is basically the same as that of example 1, except that the mass ratio of the positive electrode active material to the conductive agent and the binder is 8.5:0.25:0.5.
Example 4
Example 4 provides a positive electrode active material having the general formula Na4Fe2.95Zr0.02Ti0.02Al0.01(PO4)2(P2O7)@C.
The preparation method of the positive electrode active material of example 4 is substantially the same as that of example 1, except that aluminum nitrate is added as an aluminum source, and the calcination temperature is increased to 600 deg.c for 10 hours.
The positive electrode active material was in the form of black powder, and the median particle diameter was 6.5. Mu.m.
The preparation method of the positive electrode sheet of example 4 is basically the same as that of example 1, except that the slurry solid content is adjusted to 50%, and the single-sided area density of the sheet is adjusted to 120 g/m 2
Comparative example 1
Comparative example 1 was substantially the same as example 1 except that the zirconium source, the titanium source and the carbon source were omitted in the preparation of the positive electrode active material, and the prepared positive electrode active material was Na 4Fe4 (PO4)2(P2O7).
Comparative example 2
Comparative example 2 is substantially the same as example 1 except that the zirconium source was omitted in the preparation of the positive electrode active material.
Comparative example 3
Comparative example 3 is substantially the same as example 1 except that the titanium source was omitted in the preparation of the positive electrode active material.
Positive electrode sheets prepared from the positive electrode active materials of examples 1-4 and comparative examples 1-3 and a metal sodium negative electrode were assembled into 2032 button half batteries, and electrochemical performances were tested. The positive electrode sheets of examples 1 to 4 and comparative examples 1 to 3 were prepared into sodium ion battery cells according to the following method, and electrochemical properties were tested:
Mixing a negative electrode active material hard carbon, a conductive agent Super P, a binder SBR and a thickener CMC according to the mass ratio of 9.4:0.2:0.1:0.1, preparing slurry with the solid content of 55%, uniformly stirring, uniformly coating the slurry on an aluminum foil, and drying and rolling to obtain a negative electrode plate, wherein the single-sided surface density is 55g/m 2;
Laminating and winding the positive pole pieces, the negative pole pieces and the PP diaphragms (polypropylene diaphragms) of the examples 1-4 and the comparative examples 1-3 according to the conventional lamination and winding mode, performing liquid injection operation in a glove box with water oxygen content less than 0.5ppm, adding electrolyte 1M NaPF 6 EC: DEC=1:1, namely, the concentration of electrolyte salt in a mixed solvent of EC and DEC is 1M, the volume ratio of EC and DEC is 1:1, and packaging to obtain the sodium ion battery cell.
The test results are shown in table 1 below. The test conditions of each performance test item are that the relative humidity is less than or equal to 80 percent and the relative atmospheric pressure is 86 KPa-106 KPa.
TABLE 1
As is clear from table 1, na 4Fe4 (PO4)2(P2O7) of comparative example 1 was used as the positive electrode active material, the retention rate of the sodium ion battery cell at 500 cycles was 20%, and the 2C capacity was 963mAh. The positive electrode active materials in the examples 1-4 utilize the synergistic effect of the multi-metal elements and the carbon coating effect, so that the capacity retention rate of the sodium ion battery cell at 500 circles can reach 88%, the 2C capacity can reach 1030mAh, and the examples 1-4 show the rate performance obviously superior to that of the comparative examples 1-3. As can be seen from comparative examples 1 to 3, the technical effect of the present application cannot be achieved by either of the factors of Zr and metal M.
As can be seen from examples 1 and 4, the rate performance of the sodium ion battery is particularly remarkable when the metal M includes Zn or the metal M includes Ti and Al. As can be seen from example 2, the electrical performance of the sodium ion battery is better when the mass ratio of the positive electrode active material, the conductive agent and the binder is 8.5-9:0.25-0.6:0.25-0.6. As can be seen from the examples, when the median particle diameter of the positive electrode active material is 6-7 μm, the electron conductivity of the positive electrode active material is higher, and the rate performance is better under the condition of large rate.
The electron microscope scanning diagram of the positive electrode active material of the example 1 is shown in fig. 1, the morphology of the electron microscope scanning diagram is in a block polycrystalline structure, the grain size is about 5 μm, the charge-discharge curve of the metal sodium assembled half cell of the positive electrode active material of the example 1 at 0.2C is shown in fig. 2, the initial circle discharge capacity is about 102mAh/g, the initial circle coulomb efficiency is 85%, the charge-discharge curve of the sodium ion cell of the positive electrode active material of the example 1 at 2C is shown in fig. 3, and the discharge capacity of the sodium ion cell of the positive electrode active material of the example 1 at 0.2C is 95 mAh/g. The capacity retention rate reached 93% compared to 0.2C.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.
Claims (16)
1. The positive electrode active material is characterized by comprising an active material body, wherein the general formula of the active material body is Na 4Fe3-x-yZrxMy(PO4)2(P2O7), M is at least one of Ti, zn, V, mn, co and Al, and x is more than or equal to 0.01 and less than or equal to 0.05,0.01, and y is more than or equal to 0.05.
2. The positive electrode active material according to claim 1, further comprising a carbon coating layer provided on an outer surface of the active material body, wherein the coating amount of C is 3 to 5% of the mass of the positive electrode active material.
3. The positive electrode active material according to claim 1, wherein M comprises at least one of Ti and Al.
4. The positive electrode active material of claim 1, wherein the general formula of the active material body comprises at least one of Na4Fe2.95Zr0.02Ti0.03(PO4)2(P2O7)、Na4Fe2.94Zr0.01Zn0.05(PO4)2(P2O7) and Na 4Fe2.93Zr0.02Co0.05(PO4)2(P2O7).
5. The positive electrode active material according to any one of claims 1 to 4, wherein the median particle diameter of the positive electrode active material is 3 μm to 7 μm.
6. The positive electrode active material according to any one of claims 1 to 4, wherein the positive electrode active material is in an orthorhombic system, pn2 1 a space group, and/or the positive electrode active material has a bulk polycrystalline structure.
7. The method for producing a positive electrode active material according to any one of claims 1 to 6, comprising the steps of:
dissolving a sodium source, an iron source, a zirconium source, a metal M source, a phosphorus source and a complexing agent in a solvent according to the stoichiometric molar ratio of the anode active material, and carrying out blending treatment to obtain a mixed solution;
Drying the mixed solution to obtain mixed powder;
And sintering the mixed powder to obtain the positive electrode active material.
8. The method for producing a positive electrode active material according to claim 7, wherein at least one of:
(1) The sodium source comprises at least one of NaH 2PO4 and CH 3 COONa;
(2) The iron source includes at least one of Fe (NO 3)3、Fe(NO3)2 and FeC 2O4;
(3) The zirconium source includes Zr (at least one of NO 3)4 and Zr (CH 3COO)4;
(4) The complexing agent comprises at least one of citric acid and glucose, and/or the mole ratio of the complexing agent to metal ions in the positive electrode active material is 1.2-2:1;
(5) The metal M source is at least one of acetate, nitrate and oxide comprising metal M.
9. The method for producing a positive electrode active material according to claim 7, wherein the temperature of the sintering treatment is 500 ℃ to 700 ℃.
10. A positive electrode slurry comprising the positive electrode active material according to any one of claims 1 to 6 and comprising the positive electrode active material produced by the production method according to any one of claims 7 to 9.
11. The positive electrode slurry of claim 10, wherein the positive electrode slurry comprises the positive electrode active material, a conductive agent, a binder, and a solvent.
12. The positive electrode slurry of claim 11, wherein at least one of the following conditions is satisfied:
(1) The mass ratio of the positive electrode active material to the conductive agent to the binder is 8-9:0.25-1:0.25-1;
(2) The conductive agent comprises at least one of Super P, graphene, carbon dots, CNT and Ketjen black;
(3) The binder comprises at least one of vinylidene fluoride, polyvinylidene fluoride, and tetrafluoroethylene-hexafluoropropylene copolymer;
(4) The solid content of the positive electrode slurry is 25% -50%.
13. The positive electrode plate is characterized by comprising a positive electrode current collector and a positive electrode active layer, wherein the positive electrode active layer is arranged on at least one side of the positive electrode current collector, comprises the positive electrode active material according to any one of claims 1-6, or is prepared from the positive electrode slurry according to any one of claims 10-12.
14. The positive electrode sheet of claim 13, wherein at least one of the following conditions is satisfied:
(1) The thickness of the positive pole piece is 0.2 mm-0.6 mm;
(2) The single-sided surface density of the positive pole piece is 110g/m 2~160g/m2.
15. A sodium ion battery comprising a positive electrode sheet according to any one of claims 13 to 14.
16. An electrical device comprising a sodium ion battery as claimed in claim 15.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN120497322A (en) * | 2025-07-16 | 2025-08-15 | 甬江实验室 | Sodium ion battery positive electrode material, preparation method thereof, positive electrode plate, sodium ion battery and application of sodium ion battery positive electrode material |
| EP4611060A4 (en) * | 2023-01-16 | 2026-03-25 | Contemporary Amperex Technology Hong Kong Ltd | POSITIVE ELECTRODEACTIVITY MATERIAL AND MANUFACTURING METHOD THEREOF, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND ELECTRICAL DEVICE |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP4611060A4 (en) * | 2023-01-16 | 2026-03-25 | Contemporary Amperex Technology Hong Kong Ltd | POSITIVE ELECTRODEACTIVITY MATERIAL AND MANUFACTURING METHOD THEREOF, SECONDARY BATTERY, BATTERY MODULE, BATTERY PACK AND ELECTRICAL DEVICE |
| CN120497322A (en) * | 2025-07-16 | 2025-08-15 | 甬江实验室 | Sodium ion battery positive electrode material, preparation method thereof, positive electrode plate, sodium ion battery and application of sodium ion battery positive electrode material |
| CN120497322B (en) * | 2025-07-16 | 2025-11-11 | 甬江实验室 | Sodium ion battery positive electrode material, preparation method thereof, positive electrode plate, sodium ion battery and application of sodium ion battery positive electrode material |
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