CN115312735A - Positive electrode material and preparation method and application thereof - Google Patents

Positive electrode material and preparation method and application thereof Download PDF

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Publication number
CN115312735A
CN115312735A CN202211063660.5A CN202211063660A CN115312735A CN 115312735 A CN115312735 A CN 115312735A CN 202211063660 A CN202211063660 A CN 202211063660A CN 115312735 A CN115312735 A CN 115312735A
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positive electrode
electrode material
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coating layer
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程斯琪
陈森
王建鑫
岑杰
王伟刚
戚兴国
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Liyang Zhongke Haina Technology 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
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    • H01M4/02—Electrodes composed of, or comprising, active material
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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    • 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
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    • 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
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    • 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
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Abstract

The invention provides a positive electrode material and a preparation method and application thereof, wherein the positive electrode material comprises a kernel and a coating layer arranged on the surface of the kernel, and the chemical formula of the kernel is Na x Cu y Mn z M a O 2 Bag (bag)The coating layer comprises a Prussian blue compound and/or a polyanion compound, the layered transition metal oxide positive electrode material is modified by coating a 4.2V high-voltage section low-activity positive electrode material, uniform coating of the coating agent can be realized through a simple process, the coating layer can effectively prevent metal dissolution on the basis of ensuring sodium ion migration, catalytic decomposition of electrolyte is reduced, the coating layer can be tightly attached to the surface of the layered transition metal oxide positive electrode material by utilizing the migration of sodium ions in the charging and discharging processes, and the coating layer is prevented from falling off.

Description

Positive electrode material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of sodium ion batteries, and relates to a positive electrode material, and a preparation method and application thereof.
Background
The energy density of the sodium ion battery is relatively low, and although the layered oxide positive electrode material has higher theoretical capacity, the problems of metal dissolution, electrolyte decomposition, large gas production and the like are caused by increasing the charge cut-off voltage. In addition, the reduction of the discharge cutoff voltage, i.e., the over-discharge of the battery, may also cause severe gas generation of the battery core, and the consistency is poor, so that the large-scale application is difficult. Therefore, it is required to develop a positive electrode material capable of exhibiting a larger capacity in a wider voltage range,
wherein, the overall coating layer can obstruct electrolyte and anode materials, effectively inhibit the decomposition of the electrolyte and reduce the dissolution of metals. However, since the coating agent is difficult to achieve full-scale coating at the current coating dose, and a higher dose of the coating agent can isolate the material, electrolyte wettability is poor, and capacity exertion is poor.
CN104617267A discloses an ultrathin TiO2 coating layer of a lithium battery anode material, the lithium battery anode material and a preparation method thereof, wherein the preparation method of the lithium battery anode material comprises the following steps: dissolving a titanium-containing compound in an organic solvent; adding a core anode active substance into the solution, quickly stirring, heating to remove the organic solvent, placing the obtained dry powder in dry air for standing, slowly and controllably carrying out in-situ hydrolysis with water molecules in the air, and placing the obtained intermediate powder in an aerobic environment for calcining to obtain the lithium battery anode material.
CN104466106A discloses a coaxial cable type metal-based phosphate composite fiber positive electrode material, which is mainly formed by compounding nano phosphate active substances and metal fibers, wherein the metal fibers are used as a core, and the nano phosphate active substances are coated on the outer surfaces of the metal nanofibers to form a core-shell structure.
The coating agent of the positive electrode material in the scheme has no electrochemical activity, the coating amount is small, the coating agent is basically coated in an island mode, a complete protective layer cannot be formed, the dissolution of transition metal and the catalytic decomposition and gas production of electrolyte are difficult to be well improved, the problems of high manufacturing cost, high risk and slow coating process exist by adopting an organic solvent, and the problems of single appearance and large limitation exist by depending on an electrostatic spinning technology.
Disclosure of Invention
The invention aims to provide a positive electrode material and a preparation method and application thereof, the positive electrode material of the layered transition metal oxide is modified by coating a positive electrode material with low activity at a 4.2V high-voltage section, uniform coating of a coating agent can be realized through a simple process, the coating layer can effectively prevent metal dissolution on the basis of ensuring sodium ion migration, catalytic decomposition of electrolyte is reduced, the coating layer can be tightly attached to the surface of the positive electrode material of the layered transition metal oxide by utilizing the migration of sodium ions in the charging and discharging processes, and the coating layer is prevented from falling off.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a positive electrode material, which comprises an inner core and a coating layer arranged on the surface of the inner core, wherein the chemical formula of the inner core is Na x Cu y Mn z M a O 2 Wherein, M comprises any one or the combination of at least two of Na, mg, ni, fe, ca, B, al, zr, ti, W, mo, cr, sr, Y, cd, sn, sb, ce, li, K or Ag, x is more than or equal to 0.6 and less than or equal to 1.4,0 and less than or equal to 0.5,0 and less than or equal to z is more than or equal to 0.9,0 and less than or equal to 0.8, x +2y +3z +2a is less than or equal to 4 and +2y +3z +4a, Y + z + a =1, and the coating layer comprises Prussian blue compounds and/or polyanion compounds.
The positive electrode material adopts a physical kneading or dispersing mode that the layered sodium-poor material coats the sodium-rich material, can utilize the back-and-forth migration of an internal sodium-rich phase and an external sodium-poor phase to enable the coating to be more compact in the electrode reaction process, forms an integrally coated full-coating layer structure, can effectively reduce the contact area of the material and electrolyte, reduce metal dissolution and reduce cell gas generation caused by transition metal catalysis, and the coating agent is the positive electrode material with low high voltage activity and can inhibit the structural damage of the material caused by high voltage.
Preferably, the mass fraction of the coating layer is 0.1 to 20% based on 100% by mass of the positive electrode material, for example: 0.1%, 0.5%, 1%, 5%, 10%, 20%, etc.
The coating layer of the cathode material is a cathode material with low activity under 4.2V high voltage, the low activity under 4.2V high voltage means that the lower limit voltage is unchanged, the specific capacity difference value of the material is lower than 5mAh/g when the upper limit voltage is 4.2V and the upper limit voltage is 4.1V under 1C multiplying power, if the coating layer is a polyanion compound series, the content of the measurable index P or S or Si is 0.01-4%, and if the coating layer is a Prussian blue series, the content of the measurable index N is 0.08-8%.
Preferably, the chemical formula of the Prussian blue compound is Na m A n B o (CN) 6· pH 2 O, wherein A comprises any one or the combination of at least two of Ni, cu, fe or Co, B comprises any one or the combination of at least two of Ni, cu, fe or Co, m is more than or equal to 1.8 and less than or equal to 4,0 and more than or equal to n and less than or equal to 1.5,0 and more than or equal to 1.5, m +2n +2o is more than or equal to 6 and less than or equal to m +3n +3o, and p is more than or equal to 0.
Preferably, the polyanionic compound has the formula C c D d (EO e ) f C comprises any one or combination of at least two of Li, na or K, D comprises any one or combination of at least two of Ni, cu, fe or V, E comprises any one or combination of at least two of P, S or Si, 1 < C > 4.2,1 < D > 3,3 < D > 4, C +2d-2fe +4f < 0 < C +3D-2fe +6f.
Preferably, the prussian blue compound comprises Na 4 Fe(CN) 6 、Na 1.92 FeFe(CN) 6 、Na 1.9 CoFe(CN) 6 、Na 2 NiFe(CN) 6 Or Na 1.95 CuFe(CN) 6 Or a combination of at least two thereof.
Preferably, the polyanionic compound comprises Na 3 V 2 (PO 4 ) 3 、LiFePO 4 、Na 2 FeP 2 O 7 、Na 2 Fe P O 4 F、Na 3 V 2 O 2q (PO 4 ) 2 F 3-2q Any one or a combination of at least two of them, wherein q is 0. Ltoreq. Q.ltoreq.1.
According to the invention, the Prussian blue and polyanionic compound anode material with weak electrochemical activity at high voltage is selected as the coating agent, so that the catalytic decomposition of the layered transition metal oxide anode material on the electrolyte and the electrochemical activity of the anode material and the electrolyte interface can be reduced under the high voltage state, the side reaction is reduced, and the structural damage in the process of excessive Na intercalation is inhibited by using the electrode reaction sodium storage on the surface of the coating agent under the low voltage state.
Preferably, the pH of the positive electrode material is 11 to 12.3, for example: 11. 11.2, 11.5, 12, 12.3, etc., preferably 11.4 to 11.8.
Preferably, the BET of the positive electrode material is 0.2 to 1.0m 2 G, for example: 0.2m 2 /g、0.4m 2 /g、0.6m 2 /g、0.8m 2 G or 1.0m 2 G, etc., preferably 0.3 to 0.5m 2 /g。
In a second aspect, the present invention provides a method for preparing the positive electrode material according to the first aspect, the method comprising the steps of:
(1) Mixing a sodium source, a copper source, a manganese source and a doped metal source to obtain an oxide anode material precursor, and sintering the oxide anode material precursor to obtain a core material;
(2) And (2) mixing the core material obtained in the step (1) with a coating material, grinding, and then carrying out heat treatment to obtain the anode material.
Preferably, the sodium source of step (1) comprises sodium carbonate.
Preferably, the copper source comprises copper oxide.
Preferably, the manganese source comprises manganese dioxide.
Preferably, the doping metal source comprises any one or a combination of at least two of hydroxides and/or oxides of Mg, ni, fe, ca, B, al, zr, ti, W, mo, cr, sr, Y, cd, sn, sb, ce, li, K, ag.
Preferably, the temperature of the sintering treatment is 850 to 980 ℃, for example: 850 deg.C, 880 deg.C, 900 deg.C, 950 deg.C or 980 deg.C.
Preferably, the sintering treatment time is 10 to 24 hours, for example: 10h, 12h, 15h, 20h or 24h and the like.
Preferably, the temperature of the heat treatment in step (2) is 150 to 600 ℃, for example: 150 ℃, 180 ℃, 200 ℃, 400 ℃ or 600 ℃, preferably 170 to 500 ℃.
Preferably, the heat treatment time is 0.5 to 10 hours, for example: 0.5h, 1h, 2h, 5h or 10h and the like.
In a third aspect, the present invention provides a positive electrode plate comprising the positive electrode material according to the first aspect.
In a fourth aspect, the invention provides a sodium-ion battery comprising the positive electrode sheet according to the third aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, the anode material of the layered transition metal oxide is modified by coating the anode material with low activity at the 4.2V high-voltage section, uniform coating of the coating agent can be realized through a simple process, the coating layer can effectively prevent metal from dissolving out on the basis of ensuring sodium ion migration, catalytic decomposition of electrolyte is reduced, the coating layer can be tightly attached to the surface of the anode material of the layered transition metal oxide by utilizing the migration of sodium ions in the charging and discharging processes, and the coating layer is prevented from falling off.
(2) The method can obtain a complete coating layer by simple solid-phase coating, the dissolution of the transition metal and the catalytic decomposition of the electrolyte to generate gas are well improved, and the problems of high manufacturing cost, high risk and slow coating caused by using an organic solvent or the problems of single appearance and large limitation caused by adopting an electrostatic spinning technology are avoided.
(3) According to the invention, the layered transition metal oxide anode material is modified by coating the 4.2V high-voltage low-activity anode material, so that the cycle retention rate of the material can be obviously improved, and the material is promoted to have no obvious attenuation; the multiplying power performance is obviously improved, and the multiplying power performance is represented by the improvement of the average coulomb efficiency of different multiplying powers. In addition, the specific surface area of the material is reduced in terms of air stability, and the amount of change in the specific surface area after standing is reduced by nearly one order of magnitude.
Drawings
Fig. 1 is an SEM image of the cathode material described in example 1.
Fig. 2 is an SEM image of the cathode material described in example 2.
Fig. 3 is an SEM image of the cathode material described in example 3.
Fig. 4 is an SEM image of the cathode material described in example 4.
Fig. 5 is an SEM image of the cathode material described in example 5.
Fig. 6 is an SEM image of the cathode material described in example 6.
Fig. 7 is an SEM image of the positive electrode material described in comparative example 1.
Fig. 8 is an SEM image of the positive electrode material described in comparative example 2.
Fig. 9 is an SEM image of the positive electrode material described in comparative example 3.
Fig. 10 is an XRD pattern of the positive electrode materials described in examples 1 to 3 and comparative examples 1 to 3.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) Weigh 2.69kg Na 2 CO 3 、0.61kg Ni(OH) 2 1.43kg of CuO and 5.26kg of MnO 2 Mixing, dispersing uniformly, and drying to obtain Na 0.6 Cu 0.22 Ni 0.08 Mn 0.37 O 2 Sintering the precursor at 930 ℃ for 15h in a compressed air atmosphere at a high temperature, wherein the heating rate is 3 ℃/min, and obtaining a core material;
(2) Mixing the core material obtained in the step (1) with 250g of Na 4 Fe(CN) 6 Ball milling and mixing for 5h, ball material ratio of 1:1, then heat treating for 5h under nitrogen atmosphere at 150 ℃ to obtain Na 0.6 Cu 0.22 Ni 0.08 Mn 0.37 O 2 /0.01 Na 4 Fe(CN) 6 The positive electrode material is denoted as B1.
Example 2
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) 3.14kg of Na were weighed 2 CO 3 、0.3kgLi 2 CO 3 1.3kg of CuO and 5.26kg of MnO 2 Mixing, dispersing uniformly, and drying to obtain Na 0.7 Li 0.1 Cu 0.2 Mn 0.7 O 2 Sintering the precursor at 960 ℃ for 20h in a compressed air atmosphere at a heating rate of 3 ℃/min to obtain a core material;
(2) Mixing the core material obtained in the step (1) with 65g of Na 2 NiFe(CN) 6 Ball milling and mixing for 5h, ball material ratio of 1:1, then heat treating for 1h at 150 ℃ in nitrogen atmosphere to obtain Na 0.7 Li 0.1 Cu 0.2 Mn 0.7 O 2 /0.0025Na 2 NiFe(CN) 6 The positive electrode material is denoted as B2.
Example 3
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) Weigh 4.60kg Na 2 CO 3 、1.05kg CuO、2.69kg Ni(OH) 2 And 1.65kg MnO 2 Mixing, dispersing uniformly, and drying to obtain Na 1.4 Cu 0.22 Ni 0.48 Mn 0.3 O 2 Sintering the precursor at the high temperature of 980 ℃ in the atmosphere of compressed air for 24h, wherein the heating rate is 2 ℃/min, and obtaining a core material;
(2) Mixing the core material obtained in the step (1) with 48g LiFePO 4 Ball milling and mixing for 5h, ball-to-material ratio of 1:1, and then heat treating for 10h at 300 ℃ in nitrogen atmosphere to obtain Na 1.4 Cu 0.22 Ni 0.48 Mn 0.3 O 2 /0.005LiFePO 4 The positive electrode material is denoted as B3.
Example 4
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) Weighing 2.80kg of Na 2 CO 3 、0.03kgLi 2 CO 3 、1.29kg CuO、0.76kg Ni(OH) 2 And 5.13kg MnO 2 Mixing, dispersing uniformly, and drying to obtain Na 0.63 Li 0.01 Cu 0.2 Ni 0.1 Mn 0.69 O 2 Sintering the precursor at 920 ℃ for 13h under the atmosphere of compressed air at the heating rate of 1 ℃/min to obtain a core material;
(2) Mixing the core material obtained in the step (1) with 550g of Na 2 FeP 2 O 7 Ball milling and mixing for 5h, ball-to-material ratio of 1:1, and then heat treating for 10h at 400 ℃ in nitrogen atmosphere to obtain Na 0.63 Li 0.01 Cu 0.2 Ni 0.1 Mn 0.69 O 2 /0.025Na 2 FeP 2 O 7 The positive electrode material is denoted as B4.
Example 5
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) 3.05kg of Na are weighed out 2 CO 3 、1.30kg CuO、0.13kg Fe 2 O 3 、1.00kg Ni(OH) 2 And 4.51kg MnO 2 Mixing, dispersing uniformly, and drying to obtain Na 0.68 Cu 0.2 Fe 0.02 Ni 0.13 Mn 0.3 O 2 Sintering the precursor at 970 ℃ in a compressed air atmosphere for 16h at a high temperature, wherein the heating rate is 3 ℃/min, so as to obtain a core material;
(2) Mixing the core material obtained in the step (1) with 20g of Na 3 V 2 (PO 4 ) 3 Ball milling and mixing for 5h, ball-to-feed ratio 1:1, and then in nitrogen atmosphereHeat treating at 200 deg.C for 10h to obtain Na 0.68 Cu 0.2 Fe 0.02 Ni 0.13 Mn 0.3 O 2 /0.0005Na 3 V 2 (PO 4 ) 3 The positive electrode material is denoted as B5.
Example 6
The embodiment provides a positive electrode material, which is prepared by the following method:
(1) Weigh 2.76kg Na 2 CO 3 、0.03kgLi 2 CO 3 、1.27kg CuO、0.75kg Ni(OH) 2 、4.70kg MnO 2 And 0.49ZrO 2 Mixing, dispersing uniformly, and drying to obtain Na 0.63 Li 0.01 Cu 0.2 Ni 0.1 Mn 0.64 Zr 0.05 O 2 Sintering the precursor at a high temperature of 910 ℃ in a compressed air atmosphere for 11h at a heating rate of 4 ℃/min to obtain a core material;
(2) Mixing the core material obtained in the step (1) with 520g of Na 2 FePO 4 Ball milling and mixing for 5h, ball material ratio of 1:1, then heat treating for 1h at 500 ℃ in nitrogen atmosphere to obtain Na 0.63 Li 0.01 Cu 0.2 Ni 0.1 Mn 0.64 Zr 0.05 O 2 /0.03Na 2 FePO 4 F positive electrode material, B6.
Example 7
This example is different from example 1 only in that the sintering temperature in step (1) is 830 ℃, and other conditions and parameters are exactly the same as those in example 1.
Example 8
This example is different from example 1 only in that the sintering temperature in step (1) is 1000 ℃, and other conditions and parameters are exactly the same as those in example 1.
Example 9
This example is different from example 1 only in that the temperature of the heat treatment in step (2) is 150 ℃ and other conditions and parameters are exactly the same as those in example 1.
Example 10
This example is different from example 1 only in that the temperature of the heat treatment in step (2) is 550 ℃, and other conditions and parameters are exactly the same as those of example 1.
Comparative example 1
This comparative example differs from example 1 only in that Na is added 4 Fe(CN) 6 The alumina was replaced, and the other conditions and parameters were exactly the same as those in example 1.
Comparative example 2
This comparative example differs from example 1 only in that Na is added 4 Fe(CN) 6 Exchanged to LiFePO 4 Other conditions and parameters were exactly the same as those in example 1.
Comparative example 3
This comparative example differs from example 1 only in that Na is added 4 Fe(CN) 6 The other conditions and parameters were exactly the same as in example 1, except that zirconium dioxide was used as the zirconium dioxide.
Comparative example 4
This comparative example is different from example 1 only in that no coating treatment was performed, and other conditions and parameters were completely the same as those of example 1.
And (3) performance testing:
(1) taking the positive electrode materials obtained in examples 1-6 and comparative examples 1-3 to perform SEM and XRD tests, the test results are shown in figures 1-10, and as can be seen from figures 1-10, the positive electrode material of the invention is obviously changed compared with the positive electrode material prepared in the comparative example, B1, B4 and B6 with larger coating dosage have more comprehensive coating layers, and B5 can see more comprehensive coating layers from the figure although the coating dosage is smaller, while B2 and B3 can also see good uniformity from an EDS (electronic data System) map and well combine with an XRD (X-ray diffraction) map corresponding to figure 10, compared with characteristic peaks (marked with a P2 star and marked with an O3 star') of the laminar positive electrode material, A1-A3 basically keep unchanged, which shows that the coating does not obviously affect the material structure, and characteristic peaks of the coating agent can be observed from B1, B2 and B3, which mainly distribute on the surface. In conclusion, the high-voltage low-activity positive electrode material has a more stable crystal structure, better air stability and better electrolyte adaptability for performing full cladding modification on the layered transition metal oxide positive electrode material, and can play a role in effectively improving gas generation of the battery core.
(2) Taking the mass ratio of the cathode materials prepared in the examples 1-10 and the comparative examples 1-4 to distilled water as 1.
Weighing 50g of positive electrode material in a measuring cylinder, placing the measuring cylinder in a corresponding position of a tap density tester, vibrating for 3000 times at a vibration frequency of 80Hz, reading the volume after vibration after completion, and paralleling for three times, wherein 50/average volume is the tap density.
Subpackaging in a dry room with the low humidity of less than or equal to 5 percent, unpacking and placing for 30min in a constant humidity 50 percent environment, and simultaneously measuring BET (BET area) with another unpacked material in a 20 percent low humidity environment, wherein the difference value is a change value, and the test results are shown in table 1:
TABLE 1
Figure BDA0003826981520000101
Figure BDA0003826981520000111
As can be seen from table 1, when the coating modification of A1-A3 is performed by only using a common coating agent, and the coating modification of a small amount of other types of positive electrode materials is performed by only using a small amount of other types of positive electrode materials, the BET and BET change values are significantly larger, the pH is higher overall, and the tap density is different from each other. In addition, compared with A4 blank and B4, the pH value is obviously reduced, the tap density is not obviously reduced, the BET absolute value is reduced, and the change value after constant-humidity placement is also reduced by one order of magnitude, which shows the superiority of the coating agent and the coating structure of the method. Therefore, from the aspect of physical property characterization, the modification method of the invention can realize the effects of improving the processability of the material and improving the air stability.
(3) Taking the positive electrode materials obtained in the examples 1-6 and the comparative examples 1-4 as active substances, mixing the active substances, SP and PVDF according to a mass ratio of 90. A metal sodium sheet is used as a counter electrode, glass fiber (Waterman) is used as a diaphragm, and 1mol/L NaPF 6 EC/DMC =1:1 (Alfa) as electrolyte, applied to Ar2032 button cells are assembled in the glove box. The battery was tested at a voltage range of 2.5-4.2V, activated at 0.1C for three weeks, cycled at 1C for 100 weeks, and recorded the specific discharge capacity at the first cycle of 0.1C, the specific discharge capacity retention rate after 100 cycles at 1C, and the average coulombic efficiency at three weeks before different multiplying power, the results are shown in table 2:
TABLE 2
Figure BDA0003826981520000121
Figure BDA0003826981520000131
By combining the tables 1 and 2 and comparing the embodiment 1 with the embodiments 7 and 8, in the preparation process of the core of the cathode material, the sintering temperature affects the performance of the core, the sintering temperature is controlled to be 850-980 ℃, the performance of the prepared cathode material is good, if the sintering temperature is too low, the crystallinity of the cathode material is low, the ionic conductivity is poor, the crystal structure is unstable, the cycle life of the material is further shortened, if the sintering temperature is too high, the cathode material is seriously hardened and difficult to crush, the consistency of the crushing grain size is difficult to guarantee, and the high temperature of the material and a sintering sagger undergo a side reaction to cause the fragmentation of the sagger.
Compared with the embodiment 1 and the embodiment 9-10, the performance of the anode material prepared by the invention can be influenced by the heat treatment temperature in the preparation process of the core of the anode material, the heat treatment temperature is controlled to be 170-500 ℃, the performance of the prepared anode material is better, if the heat treatment temperature is too low, the moisture absorbed in the environment in the preparation process of the material can not be controlled, the consistency of the material is greatly influenced, particularly, the requirement of the Prussian blue series coating agent on moisture control is higher, if the heat treatment temperature is too high, the fusion of the coating agent and the transition metal element of the core can be caused at higher temperature, and in addition, if the heat treatment temperature of the coating agent is the Prussian blue series is too high, the lattice water of the material can be reduced, and the electrochemical property of the coating agent can be influenced; if the capping agent is a polyanion compound, the higher heat treatment temperature will consume the in situ carbon of the polyanion compound, and the higher heat treatment temperature will cause the crystal structure of the polyanion compound to change.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein fall within the scope and disclosure of the present invention.

Claims (10)

1. The cathode material is characterized by comprising an inner core and a coating layer arranged on the surface of the inner core, wherein the chemical formula of the inner core is Na x Cu y Mn z M a O 2 Wherein M comprises any one or combination of at least two of Na, mg, ni, fe, ca, B, al, zr, ti, W, mo, cr, sr, Y, cd, sn, sb, ce, li, K or Ag, x is more than or equal to 0.6 and less than or equal to 1.4,0 and less than or equal to 0.5,0 and less than or equal to z is more than or equal to 0.9,0 and less than or equal to 0.8, x +2y +3z +2a is less than or equal to 4 and less than x +2y +3z +4a, Y + z + a =1, and the coating layer comprises a Prussian blue compound and/or a polyanion compound.
2. The positive electrode material according to claim 1, wherein the mass fraction of the coating layer is 0.1 to 20% based on 100% by mass of the positive electrode material.
3. The positive electrode material according to claim 1 or 2, wherein the prussian blue compound has a chemical formula of Na m A n B o (CN) 6 ·pH 2 O, wherein A comprises any one or the combination of at least two of Ni, cu, fe or Co, B comprises any one or the combination of at least two of Ni, cu, fe or Co, m is more than or equal to 1.8 and less than or equal to 4,0 and more than or equal to n and less than or equal to 1.5,0 and more than or equal to 1.5, m +2n +2o is more than or equal to 6 and less than or equal to m +3n +3o, and p is more than or equal to 0;
preferably, the polyanionic compound has the formula C c D d (EO e ) f C includes any one of Li, na or KD comprises any one or combination of at least two of Ni, cu, fe or V, E comprises any one or combination of at least two of P, S or Si, 1 is more than or equal to c is more than or equal to 4.2,1 is more than or equal to D is more than or equal to 3,3 is more than or equal to D is more than or equal to 4, c +2d-2fe is more than or equal to 0 and more than or equal to c +3D-2fe +6f.
4. The positive electrode material according to any one of claims 1 to 3, wherein the Prussian blue compound comprises Na 4 Fe(CN) 6 、Na 1.92 FeFe(CN) 6 、Na 1.9 CoFe(CN) 6 、Na 2 NiFe(CN) 6 Or Na 1.95 CuFe(CN) 6 Any one or a combination of at least two of;
preferably, the polyanionic compound comprises Na 3 V 2 (PO 4 ) 3 、LiFePO 4 、Na 2 FeP 2 O 7 、Na 2 Fe P O 4 F、Na 3 V 2 O 2q (PO 4 ) 2 F 3-2q Any one or a combination of at least two of them, wherein q is 0. Ltoreq. Q.ltoreq.1.
5. The positive electrode material according to any one of claims 1 to 4, wherein the positive electrode material has a pH of 11 to 12.3, preferably 11.4 to 11.8;
preferably, the BET of the positive electrode material is 0.2 to 1.0m 2 A ratio of 0.3 to 0.5 m/g 2 /g。
6. A method for preparing a positive electrode material according to any one of claims 1 to 5, comprising the steps of:
(1) Mixing a sodium source, a copper source, a manganese source and a doped metal source to obtain an oxide anode material precursor, and sintering the oxide anode material precursor to obtain a core material;
(2) And (2) mixing the core material obtained in the step (1) with a coating material, grinding, and then carrying out heat treatment to obtain the anode material.
7. The method of claim 6, wherein the sodium source of step (1) comprises sodium carbonate;
preferably, the copper source comprises copper oxide;
preferably, the manganese source comprises manganese dioxide;
preferably, the doping metal source comprises any one or a combination of at least two of hydroxides and/or oxides of Mg, ni, fe, ca, B, al, zr, ti, W, mo, cr, sr, Y, cd, sn, sb, ce, li, K, ag;
preferably, the temperature of the sintering treatment is 850-980 ℃;
preferably, the time of the sintering treatment is 10 to 24 hours.
8. The method according to claim 6 or 7, wherein the temperature of the heat treatment in the step (2) is 150 to 600 ℃, preferably 170 to 500 ℃;
preferably, the time of the heat treatment is 0.5 to 10 hours.
9. A positive electrode sheet, characterized in that it comprises the positive electrode material according to any one of claims 1 to 5.
10. A sodium-ion battery comprising the positive electrode sheet according to claim 9.
CN202211063660.5A 2022-09-01 2022-09-01 Positive electrode material and preparation method and application thereof Pending CN115312735A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116207250A (en) * 2023-05-05 2023-06-02 北京中科海钠科技有限责任公司 Layered oxide positive electrode material, preparation method thereof, positive electrode composition, sodium ion secondary battery and application
CN117476917A (en) * 2023-12-28 2024-01-30 深圳先进技术研究院 Positive electrode material and preparation method and application thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116207250A (en) * 2023-05-05 2023-06-02 北京中科海钠科技有限责任公司 Layered oxide positive electrode material, preparation method thereof, positive electrode composition, sodium ion secondary battery and application
CN116207250B (en) * 2023-05-05 2023-08-11 北京中科海钠科技有限责任公司 Layered oxide positive electrode material, preparation method thereof, positive electrode composition, sodium ion secondary battery and application
CN117476917A (en) * 2023-12-28 2024-01-30 深圳先进技术研究院 Positive electrode material and preparation method and application thereof
CN117476917B (en) * 2023-12-28 2024-05-10 深圳先进技术研究院 Positive electrode material and preparation method and application thereof

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