CN115566183A - Positive electrode material, preparation method thereof and battery - Google Patents

Positive electrode material, preparation method thereof and battery Download PDF

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CN115566183A
CN115566183A CN202211293364.4A CN202211293364A CN115566183A CN 115566183 A CN115566183 A CN 115566183A CN 202211293364 A CN202211293364 A CN 202211293364A CN 115566183 A CN115566183 A CN 115566183A
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positive electrode
site
electrode material
doping
gel
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唐少青
郑鹏
刘惠君
王红强
郑峰华
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Shenzhen Topband Battery Co ltd
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Shenzhen Topband Battery Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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

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Abstract

The application relates to the technical field of sodium-ion batteries, in particular to a positive electrode material, a preparation method thereof and a battery. The method is used for solving the problems that the capacity attenuation of the positive electrode material of the sodium-ion battery is serious and the positive electrode material cannot be effectively utilized in the related technology. A positive electrode material with a general formula A x BO 2 (ii) a Wherein, the A site element comprises Na and a doping element X, and the doping element X is selected from one or more of K, ca, fe, mg and Li; the B site element includes Mn; wherein x is more than or equal to 0.5 and less than or equal to 1. The method is used for preparing the sodium-ion battery.

Description

Positive electrode material, preparation method thereof and battery
Technical Field
The application relates to the technical field of sodium-ion batteries, in particular to a positive electrode material, a preparation method thereof and a battery.
Background
Sodium ion batteries appeared at the earliest in the 80 s of the 20 th century, and then, since the performance of lithium ion batteries was more excellent, the research on sodium ion batteries was once stopped. However, with the increasing demand in the field of power batteries, the storage capacity of lithium ion battery materials on earth is limited, the lithium ion battery materials are expensive, and the search for backup materials of the lithium ion battery is urgent.
The sodium element has high resource storage capacity, wide distribution and low price on the earth, and shows great potential in some low-cost automobiles, large energy storage power stations and other scenes. The positive electrode material of the current sodium ion battery mainly comprises transition metal layered oxides, such as sodium manganate, sodium cobaltate, sodium nickelate and derivatives thereof, olivine, phosphosiderite sodium type sodium iron phosphate and derivatives thereof, and the like.
These layered oxides can be generally classified into two types, i.e., O3 type structures and P2 type structures. However, in the electrochemical cycle process of the existing layered oxide, due to the sliding of the sheet layer, a series of phase changes are all experienced, and especially, partial oxygen loss is caused by the oxidation of oxide ions in the oxide, so that irreversible phase change (such as O3 — P2 phase change) of the material structure is caused, and finally capacity attenuation is brought about, and how to inhibit the irreversible phase change in the electrochemical cycle process becomes a problem to be solved at present in the positive electrode material of the sodium ion battery.
Disclosure of Invention
Based on the above, the application provides a positive electrode material, a preparation method thereof and a battery, so as to solve the problem that the capacity of the positive electrode material of the sodium-ion battery is seriously attenuated and cannot be effectively utilized in the related technology.
In a first aspect of the application, a positive electrode material is provided, and the general formula of the positive electrode material is A x BO 2 ；
Wherein, the A site element comprises Na and a doping element X, and the doping element X is selected from one or more of K, ca, fe, mg and Li;
the B site element comprises Mn;
wherein x is more than or equal to 0.5 and less than or equal to 1.
In one possible embodiment of the first aspect, the molar ratio of the Na element to the doping element X in the a site element is 0.67 (0.005 to 0.05).
In one possible embodiment of the first aspect, the B site element further comprises a doping element Y, the doping element Y being selected from one or more of Ni, cu, mg, al and V.
In one possible embodiment of the first aspect, the molar ratio of the doping element Y in the B site element is less than or equal to 0.6.
In one possible embodiment of the first aspect, the positive electrode material has the chemical formula Na 0.67 Ca z Fe a Co b Mn (1-a-b) O 2 Z is 0.005 to 0.05, a is 0 to 0.2, and b is 0 to 0.2.
In a second aspect, the present application provides a method for preparing a positive electrode material, comprising:
preparing a positive electrode material by taking a preparation raw material containing an A site element, a B site element and an O element and adopting a sol-gel method; the general formula of the anode material is A x BO 2 (ii) a Wherein, the A site element comprises Na and a doping element X, and the doping element X is selected from one or more of K, ca, fe, mg and Li; the B site element includes Mn; wherein x is more than or equal to 0.5 and less than or equal to 1.
In one possible embodiment of the second aspect, the preparation raw material containing the a-site element, the B-site element, and the O element includes: one or more of acetate, nitrate, sulfate and chloride of each element in the A site elements, and one or more of acetate, nitrate, sulfate and chloride of each element in the B site elements.
In one possible embodiment of the second aspect, the preparation material is prepared by a sol-gel method, including:
preparing a mixed solution from preparation raw materials containing the A site element, the B site element and the O element;
heating and stirring the mixed solution to prepare gel;
drying and grinding the gel to obtain a precursor;
pre-sintering the precursor;
and calcining the presintered precursor, and grinding to obtain the cathode material.
In a possible embodiment of the second aspect, the drying of the gel is carried out at a temperature of 100 to 160 ℃ for a time of 10 to 20 hours.
In one possible embodiment of the second aspect, the pre-burning atmosphere is air or oxygen, the temperature of the pre-burning is 350-600 ℃, and the time is 4-6 h.
In a possible embodiment of the second aspect, the calcination is carried out at a temperature of 800 to 980 ℃ for a time of 15 to 18 hours.
In a third aspect, the present application provides a sodium ion battery comprising:
a positive electrode sheet comprising the positive electrode material according to the first aspect.
In the cathode material provided by the application, the doping element X is selected from one or more of K, ca, fe, mg and Li, and ions of the doping element have similar ionic radius with sodium ions, so that the ions of the doping element can be doped to the sodium ion sites, the obtained cathode material can effectively inhibit the irreversible phase change of the sodium ion battery in the electric energy cycle process, and tests show that when the obtained cathode material is applied to the sodium ion battery, the capacity attenuation of the sodium ion battery can be effectively inhibited, and the cycle stability and the rate capability performance of the sodium ion battery are improved.
Drawings
Fig. 1 is an XRD spectrum of the positive electrode material provided in example 1;
fig. 2 is a scanning electron microscope image of the cathode material provided in example 1;
fig. 3 is a first charge and discharge test chart of a battery prepared from the cathode material provided in example 1;
fig. 4 is a graph illustrating the rate performance test of a battery fabricated from the positive electrode material provided in example 1;
fig. 5 is a graph showing the cycle performance test of a battery fabricated using the cathode material provided in example 1.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying 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 in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The present application will be described in further detail with reference to specific examples. This application may be embodied in many different forms and is not limited to the embodiments described 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 present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In this application, "one or more" means any one, any two, or any two or more of the listed items. Wherein, the 'several' means any two or more than any two.
In the present application, the terms "combination thereof", "any combination thereof", and the like, used herein, include all suitable combinations of any two or more of the listed items.
In the present application, "preferred" is merely a description of better embodiments or examples, and it should be understood that the scope of the present application is not limited thereto.
In the present application, the technical features described in the open manner include a closed technical solution including the listed features, and also include an open technical solution including the listed features.
In the present application, reference to a numerical range includes both end points of the numerical range unless otherwise specified.
In the present application, the percentage content refers to both the mass percentage for solid-liquid mixing and solid-solid phase mixing, and the volume percentage for liquid-liquid phase mixing, unless otherwise specified.
In this application, reference to percent concentrations, unless otherwise stated, refers to final concentrations. The final concentration refers to the ratio of the added component in the system after the component is added.
In the present application, the temperature parameter is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
In view of the problem of capacity fade caused by irreversible phase transition of the positive electrode material of the sodium-ion battery in the related art, the inventors of the present application sought a positive electrode material that is element-doped at the Na element site. The element doping can effectively inhibit the structural phase change of the sodium-ion battery in the electrochemical cycle process, so that the capacity attenuation problem of the sodium-ion battery can be effectively inhibited, and the specific implementation mode is described as follows:
some embodiments of the present application provide a positive electrode material for sodium ion batteries, the positive electrode material having a general formula A x BO 2 (ii) a Wherein, the A site element comprises Na and a doping element X, and the doping element X is selected from one or more of K, ca, fe, mg and Li; the B site element comprises Mn; wherein x is more than or equal to 0.5 and less than or equal to 1.
The doping element X is selected from one or more of K, ca, fe, mg and Li, and ions of the doping element have similar ionic radius with sodium ions, so that the ions can be doped to sodium ion sites, the obtained positive electrode material can effectively inhibit irreversible phase change of the sodium ion battery in the electric energy cycle process, and tests show that the obtained positive electrode material can effectively inhibit capacity attenuation of the sodium ion battery when applied to the sodium ion battery, and improve cycle stability and rate capability of the sodium ion battery.
The doping amount of the doping element X is not particularly limited, as long as the doping element X is introduced to effectively dope a part of the sodium ion sites.
In some embodiments, the molar ratio of Na element to doping element X in the a-site elements is 0.67: (0.005-0.05).
In these embodiments, by controlling the molar ratio of the Na element to the doping element X within the above range, it is possible to effectively suppress the occurrence of irreversible phase transition in the sodium-ion battery while ensuring the sodium-ion content in the sodium-ion battery.
In some embodiments, the B site elements further comprise a doping element Y selected from one or more of Co, fe, ni, cu, mg, al and V.
In these embodiments, by doping the doping element Y at the B site, the positive electrode material can be further prevented from undergoing an irreversible phase change.
In some embodiments, the molar ratio of the doping element Y in the B site elements is less than or equal to 0.6.
In these embodiments, by controlling the molar ratio of the doping element Y within the above range, the irreversible phase change of the sodium ion battery can be effectively suppressed.
In some embodiments, the positive electrode material has the chemical formula Na 0.67 Ca z Fe a Co b Mn (1-a-b) O 2 Z is 0.005-0.05, a is 0-0.2, b is 0-0.2.
In some embodiments, the positive electrode material has the chemical formula Na 0.67 Co 0.1 Fe 0.1 Mn 0.8 O 2 。
The embodiment of the application also provides a preparation method of the cathode material, which comprises the following steps:
preparing a positive electrode material by taking a preparation raw material containing an A site element, a B site element and an O element and adopting a sol-gel method; the general formula of the anode material is A x BO 2 (ii) a Wherein the A site element comprises Na and doping element XX is selected from one or more of K, ca, fe, mg and Li; the B site element includes Mn; wherein x is more than or equal to 0.5 and less than or equal to 1.
The sol-gel method is a process of dispersing raw materials in a solvent, then generating active monomers through hydrolysis reaction, polymerizing the active monomers to form sol, and aging the sol to form gel with a certain spatial structure. The gel is dried and heat treated to obtain the required material.
In some embodiments, a preparation feedstock comprising an a-site element, a B-site element, and an O element comprises: one or more of acetate, nitrate, sulfate and chloride of each element in the A site elements, and one or more of acetate, nitrate, sulfate and chloride of each element in the B site elements.
For example, taking the example that the a site element includes Na and the dopant element Ca, and the B site element includes Mn and the dopant element Co, the raw material for preparing the material including the a site element, the B site element, and the O element may include: sodium acetate, calcium nitrate, manganese chloride and cobalt sulfate.
In some embodiments, the positive electrode material is prepared using a sol-gel method comprising:
preparing a preparation raw material containing an A site element, a B site element and an O element into a mixed solution;
heating and stirring the mixed solution to prepare gel;
drying and grinding the gel to obtain a precursor;
pre-sintering the precursor;
and calcining the presintered precursor, and grinding to obtain the cathode material.
In these embodiments, the mixed solution may be an aqueous solution. By pre-sintering the obtained precursor, the decomposition reaction in the precursor can be fully performed, so that impurity ions in the anode material can be reduced, and the purity of the oxide can be improved.
In some embodiments, the gel is dried at a temperature of 100 to 160 ℃ for a time of 10 to 20 hours.
In some embodiments, the pre-sintering atmosphere is air or oxygen, the temperature of the pre-sintering is 350-600 ℃, and the time is 4-6 h.
In these embodiments, the positive electrode material can be sufficiently oxidized, and oxygen loss after the desorption of sodium ions can be suppressed, so that the capacity fade can be reduced.
In some embodiments, the pre-firing is at a ramp rate of 4 to 6 deg.C/min.
In some embodiments, the calcination is carried out at a temperature of 800 to 980 ℃ for a time of 15 to 18 hours.
Embodiments of the present application also provide a sodium ion battery, comprising:
the cathode comprises a cathode plate, electrolyte and a diaphragm, wherein the cathode plate comprises the cathode material.
The anode material can be prepared into slurry to be coated on an aluminum electrode or an aluminum alloy electrode, and the anode plate is obtained by compacting.
The technical effect of the sodium ion battery provided in the embodiment of the present application is substantially the same as that of the positive electrode material provided in the embodiment of the present application, and is not described herein again.
The embodiments of the present application are introduced above, and in order to objectively explain the technical effects produced by the present application, next, description will be made by the following examples and comparative examples.
In the following examples and comparative examples, all raw materials were commercially available, and in order to maintain the reliability of the experiment, the raw materials used in the following examples and comparative examples all had the same physical and chemical parameters or were subjected to the same treatment.
Comparative example 1
Preparation of Na 0.67 MnO 2 Layered positive electrode material
Step 1), weighing a certain amount of manganese acetate, sodium acetate and citric acid, adding into a beaker, adding into a certain amount of deionized water for dissolving, and stirring in a water bath at 60 ℃ until the solution is gelatinous.
And 2) putting the obtained gel into a vacuum oven, and drying for 15h at 120 ℃ in a vacuum state to obtain dry gel.
Step 3), drying the dried gelDrying, pouring into a mortar, grinding into powder, placing into a burning boat, placing into a tube furnace, heating to 400 ℃ at a heating rate of 5 ℃/min in an air atmosphere, presintering at 400 ℃ for 5h, heating to 900 ℃, keeping the temperature for 15h, and cooling to room temperature; grinding the calcined material into powder to obtain Na 0.67 MnO 2 A layered positive electrode material.
Comparative example 2
Preparation of Na 0.67 Fe 0.1 Mn 0.9 O 2 Layered positive electrode material
Step 1), weighing a certain amount of manganese acetate, ferric acetate, sodium acetate and citric acid, adding into a beaker, adding into a certain amount of deionized water for dissolving, and stirring in a water bath at 60 ℃ until the solution is gelatinous.
And 2) putting the obtained gel into a vacuum oven, and drying for 15h at 120 ℃ in a vacuum state to obtain dry gel.
Step 3), pouring the dry gel into a mortar to be ground into powder, putting the powder into a burning boat, putting the burning boat into a tubular furnace, heating the temperature of the tubular furnace to 400 ℃ at the heating rate of 5 ℃/min in the air atmosphere, presintering the powder for 5 hours at 400 ℃, heating the powder to 900 ℃, keeping the temperature for 15 hours, and cooling the powder to the room temperature; grinding the calcined material into powder to obtain Na 0.67 Fe 0.1 Mn 0.9 O 2 A layered positive electrode material.
Comparative example 3
Preparation of Na 0.67 Co 0.1 Mn 0.9 O 2 Layered positive electrode material
Step 1), weighing a certain amount of manganese acetate, cobalt acetate, sodium acetate and citric acid, adding into a beaker, adding into a certain amount of deionized water for dissolving, and stirring in a water bath at 60 ℃ until the solution is gelatinous.
And 2) putting the obtained gel into a vacuum oven, and drying for 15h at 120 ℃ in a vacuum state to obtain dry gel.
Step 3), pouring the dry gel into a mortar to be ground into powder, putting the powder into a burning boat, putting the burning boat into a tubular furnace, heating the tubular furnace to 400 ℃ at the heating rate of 5 ℃/min in the air atmosphere, presintering the powder for 5h at 400 ℃, heating the powder to 900 ℃, preserving the heat for 15h, and cooling the powder to the room temperature; calcining the mixtureGrinding the good material into powder to obtain Na 0.67 Co 0.1 Mn 0.9 O 2 A layered positive electrode material.
Comparative example 4
Preparation of Na 0.67 Co 0.1 Fe 0.1 Mn 0.8 O 2 Layered positive electrode material
Step 1), weighing a certain amount of manganese acetate, iron acetate, cobalt acetate, sodium acetate and citric acid, adding into a beaker, adding into a certain amount of deionized water for dissolving, and stirring in a water bath at 60 ℃ until the solution is gelatinous.
And step 2), putting the obtained gel into a vacuum oven, and drying for 15 hours at 120 ℃ in a vacuum state to obtain dry gel.
Step 3), pouring the dry gel into a mortar to be ground into powder, putting the powder into a burning boat, putting the burning boat into a tubular furnace, heating the tubular furnace to 400 ℃ at the heating rate of 5 ℃/min in the air atmosphere, presintering the powder for 5h at 400 ℃, heating the powder to 900 ℃, preserving the heat for 15h, and cooling the powder to the room temperature; grinding the calcined material into powder to obtain Na 0.67 Co 0.1 Fe 0.1 Mn 0.8 O 2 A layered positive electrode material.
Example 1
Preparation of Na 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 Layered positive electrode material
Step 1), weighing a certain amount of manganese acetate, iron acetate, cobalt acetate, sodium acetate, calcium acetate and citric acid, adding into a beaker, adding into a certain amount of deionized water for dissolving, and stirring in a water bath at 60 ℃ until the solution is gelatinous.
And step 2), putting the obtained gel into a vacuum oven, and drying for 15 hours at 120 ℃ in a vacuum state to obtain dry gel.
Step 3), pouring the dry gel into a mortar to be ground into powder, putting the powder into a burning boat, putting the burning boat into a tubular furnace, heating the tubular furnace to 400 ℃ at the heating rate of 5 ℃/min in the air atmosphere, presintering the powder for 5h at 400 ℃, heating the powder to 900 ℃, preserving the heat for 15h, and cooling the powder to the room temperature; grinding the calcined material into powder to obtain Na 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 A layered positive electrode material.
Examples of the experiments
1. XRD analysis: na obtained in example 1 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 The layered positive electrode material was subjected to X-ray diffraction analysis to obtain Na 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 The diffraction pattern of the layered positive electrode material is shown in fig. 1.
2. And (3) morphology testing: scanning Electron microscopy on Na obtained in example 1 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 The micro-morphology of the layered positive electrode material is characterized to obtain Na shown in figure 2 0.67 Ca 0.005 Co 0.1 Fe 0.1 Mn 0.8 O 2 And (4) a micro-topography map.
3. And (3) electrochemical performance testing:
in the above examples and comparative examples, electrochemical performance tests were performed on button cells using a battery test system.
The button cell comprises the following preparation processes:
preparing a pole piece: the positive electrode material is used as an active material in the battery, is prepared into slurry with a binder and a conductive agent, is coated on an aluminum foil and is dried for 12 hours at 120 ℃, and is subjected to punch forming under the pressure of 100MPa to prepare the positive electrode plate. Wherein, the binder can be PVDF, the conductive agent can be SP and KS-6, the solvent used in preparing the slurry can be NMP, and the mass ratio of NMP, the active material, the binder and the conductive agent can be 85.
Assembling the battery: and (3) assembling the positive pole piece, the diaphragm, the negative pole piece and the electrolyte into a button cell in an argon-filled glove box with the water content and the oxygen content of less than 5ppm, and standing for 6 hours. Wherein, the negative pole piece is a metal sodium piece.
And controlling the charging and discharging voltage interval to be 1.5-4.3V, and carrying out charging and discharging tests on the button cell at the current density of 0.1C at room temperature to evaluate the first discharging specific capacity of the multi-element anode material.
And (3) testing the cycle performance: and controlling the charging and discharging voltage interval to be 1.5-4.3V, and at room temperature, cycling the charge and discharge of the button cell at 1C for 100 times to evaluate the capacity retention rate of the cathode material.
And (3) rate performance test: controlling the charging and discharging voltage interval to be 1.5-4.3V, and carrying out charging and discharging circulation for 20 times at the multiplying power of 5C at room temperature, and evaluating the multiplying power performance of the anode material by taking the first discharging specific capacity as a reference.
And (3) testing results:
1. as shown in fig. 1, an XRD analysis pattern of the cathode material provided in example 1 shows that the cathode material has better crystallinity as shown in fig. 1.
2. As shown in fig. 2, which is a scanning electron microscope image of the cathode material provided in example 1, it can be seen from fig. 2 that the cathode material has relatively uniform particles, a high tap density, and a product secondary particle size of about 2 μm.
3. As shown in table 1 below, the results of electrochemical performance tests of the batteries prepared for the positive electrode materials provided in the comparative examples and examples. As shown in fig. 3, a graph of the first specific discharge capacity test result of the battery prepared from the cathode material provided in example 1, as shown in fig. 4, a graph of the rate performance of the battery prepared from the cathode material provided in example 1, and as shown in fig. 5, a graph of the cycle performance of the battery prepared from the cathode material provided in example 1.
Table 1: electrochemical Properties of example 1 and comparative examples 1 to 4
Figure BDA0003902233330000101
As shown in Table 1 and FIG. 3, the specific first discharge capacity of the positive electrode material provided in example 1 was as high as 188mAh/g.
As shown in table 1 and fig. 4, compared with comparative examples 1 to 4, the positive electrode material provided in example 1 has better rate performance, and the rate performance is directly related to the mobility of sodium ions, so that it can be obtained that the mobility of sodium ions in the positive electrode material provided in example 1 is better. In addition, as the higher the capacity discharged at a high rate is, the better the battery performance is, and as the reversible capacity is larger, the more the battery performance is maintained, and the capacity fading is reduced, therefore, by testing the reversible specific capacity of the positive electrode material provided in the comparative example and the example at the 5C rate, as can be seen from table 1 and fig. 4, compared with comparative examples 1 to 4, the reversible specific capacity of the positive electrode material provided in example 1 at the 5C rate can reach 55mAh/g, which indicates that the capacity fading of the positive electrode material provided in example 1 is smaller, and the cycling stability is good.
As shown in table 1 and fig. 5, compared with comparative examples 1 to 4, the positive electrode material provided in example 1 is charged and discharged at a current density of 1C, and when the cycle number is 100, the retention rate of the specific capacity can reach 70%, and the coulombic efficiency can reach 100%, which indicates that the positive electrode material provided in example 1 has a high capacity retention rate, good cycle performance, less capacity attenuation, and good electrochemical performance.
In conclusion, by doping the sodium element sites, the cycling stability and the rate capability of the cathode material can be effectively improved, the capacity attenuation is reduced, and good conditions are provided for the application of the sodium-ion battery.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (12)

1. The cathode material is characterized in that the general formula of the cathode material is A x BO 2 ；
The A site element comprises Na and a doping element X, wherein the doping element X is selected from one or more of K, ca, fe, mg and Li;
the B site element comprises Mn;
wherein x is more than or equal to 0.5 and less than or equal to 1.
2. The positive electrode material according to claim 1,
in the A site elements, the molar ratio of Na element to doping element X is 0.67: (0.005-0.05).
3. The positive electrode material according to claim 1 or 2,
the B site element also comprises a doping element Y, and the doping element Y is selected from one or more of Co, fe, ni, cu, mg, al and V.
4. The positive electrode material according to claim 3,
and in the B site elements, the molar ratio of a doping element Y is less than or equal to 0.6.
5. The positive electrode material according to claim 1,
the chemical formula of the anode material is Na 0.67 Ca z Fe a Co b Mn (1-a-b) O 2 Z is 0.005 to 0.05, a is 0 to 0.2, and b is 0 to 0.2.
6. A method for preparing a positive electrode material, comprising:
preparing a preparation raw material containing an A site element, a B site element and an O element by adopting a sol-gel method;
the general formula of the cathode material is A x BO 2 ；
The A site element comprises Na and a doping element X, wherein the doping element X is selected from one or more of K, ca, fe, mg and Li;
the B site element comprises Mn;
wherein x is more than or equal to 0.5 and less than or equal to 1.
7. The method of claim 6,
the preparation raw materials containing the A site element, the B site element and the O element comprise: one or more of acetate, nitrate, sulfate and chloride of each element in the A site elements, and one or more of acetate, nitrate, sulfate and chloride of each element in the B site elements.
8. The method of claim 6, wherein the preparation material is prepared by a sol-gel method comprising:
preparing a preparation raw material containing the A site element, the B site element and the O element into a mixed solution;
heating and stirring the mixed solution to prepare gel;
drying and grinding the gel to obtain a precursor;
pre-sintering the precursor;
and calcining the presintered precursor, and grinding to obtain the cathode material.
9. The method of claim 8,
the temperature for drying the gel is 100-160 ℃, and the time is 10-20 h.
10. The method of claim 8,
the presintering atmosphere is air or oxygen, the presintering temperature is 350-600 ℃, and the presintering time is 4-6 h.
11. The method of claim 8,
the calcining temperature is 800-980 ℃ and the calcining time is 15-18 h.
12. A sodium ion battery, comprising:
a positive electrode sheet comprising the positive electrode material according to any one of claims 1 to 5.
CN202211293364.4A 2022-10-21 2022-10-21 Positive electrode material, preparation method thereof and battery Pending CN115566183A (en)

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