CN116031380A - Polycrystalline sodium ion-like positive electrode material, and preparation method and application thereof - Google Patents

Polycrystalline sodium ion-like positive electrode material, and preparation method and application thereof Download PDF

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CN116031380A
CN116031380A CN202211743472.7A CN202211743472A CN116031380A CN 116031380 A CN116031380 A CN 116031380A CN 202211743472 A CN202211743472 A CN 202211743472A CN 116031380 A CN116031380 A CN 116031380A
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polycrystalline
sodium ion
positive electrode
electrode material
sintering
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朱青林
姜政志
叶昱昕
仰韻霖
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Guangdong Kaijin New Energy Technology Co Ltd
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Abstract

The invention discloses a polycrystalline sodium ion-like positive electrode material, a preparation method and application thereof, wherein the sodium ion positive electrode material comprises a core and a coating layer, and the chemical formula of the material in the core is Na α Ni x Mn y M (1‑x‑y) O 2 The coating layer is oxide. The preparation method comprises the following steps: (1) NiO, mnO 2 Mixing the doping agent with the first sodium salt to obtain a mixture A; (2) Sintering the mixture A for the first time, and then crushing to obtain a polycrystalline-like material A, wherein the average particle size of the polycrystalline-like material A is controlled to be 4-7um through crushing; (3) Polycrystalline material A is mixed withMixing the second sodium salt to obtain a mixed material B, and performing secondary sintering to obtain a polycrystalline-like material B; (4) And mixing the polycrystalline material B with a coating agent, and performing third sintering to obtain the polycrystalline sodium ion anode material. The sodium ion positive electrode material is internally made of polycrystalline-like materials, is internally doped with substances with stable crystal structures, has the advantages of large particle size, small specific surface area, high structural stability, high rate capability and long cycle life.

Description

Polycrystalline sodium ion-like positive electrode material, and preparation method and application thereof
Technical Field
The invention relates to the technical field of sodium ion battery anode materials, in particular to a polycrystalline sodium ion-like anode material, a preparation method and application thereof.
Background
In order to solve the problems of increasingly exhausted fossil fuel, shortage of lithium resources and the like, the sodium ion battery is considered to be a secondary battery with great potential in developing new energy, large-scale energy storage and low-speed electric vehicles with the advantages of abundant resources, low theoretical cost, good quick charge performance, excellent low-temperature performance and the like. The sodium ion battery anode material is one of important factors influencing parameters such as battery energy density, cycle performance, rate capability and the like. The positive electrode material of the sodium ion battery comprises transition metal oxide, polyanion compounds, prussian blue compounds and organic compounds. Among them, layered oxides are of greatest interest due to their higher specific capacity and structure similar to that of positive electrode materials of lithium ion batteries. In order for the layered oxide material to meet the battery cycle life requirements, reducing the specific surface area of the material by increasing the particle size of the material, reducing the occurrence of side reactions is a relatively simple and effective measure. The following difficulties remain: firstly, the circulation performance of the material is improved by increasing the size of particles, but the diffusion side length of sodium ions from the inside to the surface layer is reduced, and the sodium ion intercalation and deintercalation dynamic performance is poor; secondly, preparing a polycrystalline material, wherein BET of the material is reduced, and surface side reactions are less, but in the charge and discharge process, the volume change causes stress, so that the polycrystalline is cracked, a new interface is formed, and the cycle performance of the material is deteriorated.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a polycrystalline sodium ion-like positive electrode material, a preparation method and an application thereof, wherein the interior of the sodium ion-like positive electrode material is polycrystalline-like material, a substance with a stable crystal structure is doped in the interior of the sodium ion-like positive electrode material, and a layer of metal oxide is coated on the surface of the sodium ion-like positive electrode material.
In order to achieve the above object, the first aspect of the present invention provides a polycrystalline sodium ion-like positive electrode material comprising a core and a coating layer, wherein the material in the core has a chemical formula of Na α Ni x Mn y M (1-x-y) O 2 The material in the coating layer is oxide, wherein alpha is more than 0.60 and less than or equal to 1.0, x is more than 0 and less than or equal to 0.80,0, and y is more than 0 and less than or equal to 0.80; m is at least one of Zr, al, co, cu, sr, Y, ti, mg, K, fe, ca, li, mo, B, sn, si, nb, zn, W, tc and Ru.
In some embodiments, the oxide is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them.
In some embodiments, the material in the core has the formula Na 0.85 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The material in the coating layer is Al 2 O 3 。
In some embodiments, the material in the inner core has the formula Na 0.85 Ni 0.4 Mn 0.5 Cu 0.1 O 2 The coating layer is TiO 2 。
In some embodiments, the polycrystalline sodium ion-like positive electrode material is a polycrystalline-like morphology formed of a plurality of small particles having an average particle size of 4-7um, and the polycrystalline sodium ion-like positive electrode material may have an average particle size of, by way of example, but not limited to, 4 um, 5 um, 6 um, 7 um.
In some embodiments, the polycrystalline sodium ion-like positive electrode material has a specific surface area of 0.2-0.5m 2 By way of example, the specific surface area may be, but is not limited to, 0.2m 2 /g、0.3m 2 /g、0.4m 2 /g、0.5m 2 /g。
The second aspect of the invention provides a method for preparing a polycrystalline sodium ion-like positive electrode material, comprising the steps of:
(1) NiO and MnO are mixed according to the formula amount 2 Mixing the doping agent with the first sodium salt to obtain a mixture A;
(2) Sintering the mixture A for the first time, and then crushing to obtain a polycrystalline-like material A, wherein the average particle size of the polycrystalline-like material A is controlled to be 4-7um through crushing;
(3) Mixing the polycrystalline-like material A with a second sodium salt to obtain a mixed material B, and then performing secondary sintering to obtain the polycrystalline-like material B;
(4) And mixing the polycrystalline material B with a coating agent, and performing third sintering to obtain the polycrystalline sodium ion anode material.
The preparation method of the polycrystalline sodium ion-like positive electrode material has the following technical effects:
(1) The chemical formula of the polycrystalline sodium ion-like positive electrode material is Na α Ni x Mn y M (1-x-y) O 2 The sodium ion positive electrode material is of a polycrystalline-like morphology, a plurality of primary particles are fused together, substances which stabilize the crystal structure of the material are doped in the particles, and the surfaces of the particles are coated with a layer of metal oxide. Such polycrystalline sodium ion positive electrode materials have the following advantages:
firstly, the structure has the advantages of polycrystal and monocrystal, the particles are formed by melting a plurality of primary particles, the plurality of primary particles can improve the multiplying power performance of the material, and the particles are grown together through molten salt by adding the second sodium salt in the second sintering, so that the binding force exceeds the contact between the primary particles of the polycrystal material, and the particles have good stability to the particle stress caused by the volume change of the material in the charging and discharging process, thereby realizing better multiplying power performance on the basis of realizing long cycle performance;
secondly, oxide is coated on the surface, and the oxide reacts with residual sodium on the surface of the material at a certain temperature to form a sodium fast ion conductor which is uniformly coated on the surface of the material, so that the residual sodium on the surface of the material is reduced, the ion conductivity of the sodium is increased, the contact between the positive electrode material and electrolyte is isolated, and M metal ions are doped in the positive electrode material to stabilize the structure of the positive electrode material, so that the long cycle and high rate performance of the battery are realized.
(2) The second sodium salt is added into the polycrystalline-like material A as a fluxing agent, primary particles grow together, the particles grow together through molten salt, the binding force exceeds the contact between the primary particles of the polycrystalline material, and the particle stress caused by the change of the volume of the material in the charge and discharge process has good stability, so that better rate performance can be realized on the basis of realizing the long cycle performance of the battery, and finally, the battery is coated by combining with a coating agent, so that unreacted sodium salt is consumed, the process for preparing the material is simple, the cost is low, and the battery can be industrially produced.
In some embodiments, the dopant is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them. By way of example, it may be, but is not limited to, cuO, tiO 2 ZnO, and the like.
In some embodiments, the first sodium salt is NaOH, naNO 3 、Na 2 CO 3 Or CH (CH) 3 At least one of COONa, wherein the second sodium salt is NaOH or NaNO 3 、Na 2 CO 3 Or CH (CH) 3 At least one of COONa. It will be appreciated that the first sodium salt may be the same as the second sodium salt or may be different. The addition of the second sodium salt strengthens primary particles of the agglomerated sodium ion positive electrode material sintered for the first time through a solid-phase molten salt method, so that single particles are tightly combined, disintegration caused by volume change in a cyclic process is inhibited, and the reinforced polycrystalline-like sodium ion positive electrode material has better cyclic performance, maintains a polycrystalline state and maintainsHigher rate capability.
In some embodiments, the first sintering is performed under oxygen-passing conditions.
In some embodiments, the first sintering is performed at a temperature of 600 ℃ to 850 ℃ for 3-8 hours, and then to 850-950 ℃ for 8-16 hours. As an example, the first sintering process is: introducing air, heating to 600-850 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 3-8h, heating to 850-950 ℃ and preserving heat for 8-16h, and naturally cooling to room temperature to obtain the black block material.
In some embodiments, in the step (3), the amount of the second sodium salt added is 1-10% of the mass of the polycrystalline-like material a, and as an example, the amount of the second sodium salt added is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the polycrystalline-like material a, but not limited thereto.
In some embodiments, the second sintering is performed under oxygen-passing conditions.
In some embodiments, the second sintering is performed at a temperature of 400 ℃ to 800 ℃ for 4-12 hours. Further, after the second sintering is finished, the material is sieved by a 300-mesh sieve to obtain a polycrystalline-like material B. As an example, the process of the second sintering is: introducing air, heating to 400-800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 4-12h, naturally cooling to room temperature, and sieving with a 300-mesh sieve to obtain the polycrystalline-like material B.
In some embodiments, the capping agent is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them.
In some embodiments, the third sintering is performed under oxygen-passing conditions.
In some embodiments, the third sintering is performed at a temperature of 300 ℃ to 600 ℃ for 4-8 hours, and further, after the third sintering is finished, the polycrystalline sodium ion-like positive electrode material is obtained through a 300-mesh sieve. As an example, the third sintering process is: introducing air, heating to 300-600deg.C at a heating rate of 2.5deg.C/min, maintaining for 4-8 hr, naturally cooling to room temperature, sieving with 300 mesh sieve, and making into polycrystalline sodium ion-like positive electrode material.
In some embodiments, in step (1), the molar ratio of sodium to metallic elements (Ni, fe and M of dopant) is (0.5-0.85): 1, wherein M is at least one of Zr, al, co, cu, sr, Y, ti, mg, K, ca, li, mo, B, sn, si, nb, zn, W, tc and Ru.
In some embodiments, the crushing comprises sequentially rotary wheel grinding and jet mill crushing, wherein the average size of polycrystalline-like particles of crushed materials is 4.0-7.0 mu m through the jet mill, so as to obtain polycrystalline-like materials A;
in some embodiments, the coating agent is used in an amount of 0.2-2% by mass of the polycrystalline-like material B, and as an example, the coating agent is added in an amount of 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2% by mass of the polycrystalline-like material B, but not limited thereto.
The invention also provides application of the polycrystalline sodium ion-like positive electrode material in sodium ion batteries. The polycrystalline sodium ion positive electrode material is used in a sodium ion battery and has the advantages of high rate capability and long cycle life.
Drawings
Fig. 1 is an SEM image of a polycrystalline sodium-like cathode material prepared in example 1 of the present invention.
Fig. 2 is a graph showing XRD test results of the polycrystalline sodium ion-like positive electrode material prepared in example 1 of the present invention.
Fig. 3 is a first charge-discharge curve of the polycrystalline sodium ion-like positive electrode material prepared in example 1 of the present invention.
Detailed Description
The conception and the technical effects produced by the present invention will be clearly and completely described in conjunction with the embodiments below to fully understand the objects, features and effects of the present invention. It is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments, and that other embodiments obtained by those skilled in the art without inventive effort are within the scope of the present invention based on the embodiments of the present invention.
Example 1
The polycrystalline sodium ion-like positive electrode material of the embodiment comprises a core and a coating layer, wherein the chemical formula of the material in the core is Na 0.85 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The coating layer is Al 2 O 3 。
The preparation method of the polycrystalline sodium ion-like positive electrode material comprises the following steps:
(1) By NiO, mnO 2 ZnO and Na 2 CO 3 Raw materials, ni: mn: zn element mol ratio is 4:5:1, sodium and metal element mol ratio is 0.75:1, weighing the raw materials and uniformly mixing in a high-speed mixer to obtain a mixture A;
(2) Placing the mixture A in a box furnace for sintering, introducing air, heating to 800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, heating to 950 ℃ for preserving heat for 12 hours, naturally cooling to room temperature to obtain a block material, and sequentially carrying out rotary wheel grinding and jet milling on the block material, and crushing the block material into polycrystalline-like particles with an average size of 5.1 mu m to obtain the polycrystalline-like material A;
(3) Uniformly mixing the polycrystalline-like material A with NaOH in a high-speed mixer, wherein the adding amount of the NaOH is 3.67% of the mass of the polycrystalline-like material A to obtain a mixed material B, placing the mixed material B in a box-type furnace, then introducing air, heating to 700 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, naturally cooling to room temperature, and sieving with a 300-mesh sieve to obtain the polycrystalline-like material B;
(4) Mixing polycrystalline material B with Al 2 O 3 Mixing in a high-speed mixer, and placing into a box furnace, al 2 O 3 The adding amount of the catalyst is 1 percent of the mass of the polycrystalline material B, air is introduced, the temperature is increased to 450 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the catalyst is naturally cooled to room temperature, and the catalyst is sieved by a 300-mesh sieve, thus obtaining the catalystTo a polycrystalline sodium ion-like positive electrode material.
Example 2
The polycrystalline sodium ion-like positive electrode material of the embodiment comprises a core and a coating layer, wherein the chemical formula of the material in the core is Na 0.85 Ni 0.4 Mn 0.5 Cu 0.1 O 2 The coating layer is TiO 2 。
The preparation method of the polycrystalline sodium ion-like positive electrode material comprises the following steps:
(1) By NiO, mnO 2 CuO and Na 2 CO 3 Raw materials, ni: mn: zn element mol ratio is 4:5:1, sodium and metal element mol ratio is 0.75:1, weighing the raw materials and uniformly mixing in a high-speed mixer to obtain a mixture A;
(2) Placing the mixture A in a box furnace for sintering, introducing air, heating to 800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, heating to 950 ℃ for preserving heat for 12 hours, naturally cooling to room temperature to obtain a block material, and sequentially carrying out rotary wheel grinding and jet milling on the block material, and crushing the block material into polycrystalline-like particles with an average size of 5.4 mu m to obtain the polycrystalline-like material A;
(3) Uniformly mixing the polycrystalline-like material A with NaOH in a high-speed mixer, wherein the adding amount of the NaOH is 3.67% of the mass of the polycrystalline-like material A to obtain a mixed material B, placing the mixed material B in a box-type furnace, introducing air, heating to 700 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, naturally cooling to room temperature, and sieving with a 300-mesh sieve to obtain the polycrystalline-like material B;
(4) Mixing polycrystalline material B with Al 2 O 3 Mixing in a high-speed mixer, and placing into a box furnace, al 2 O 3 The adding amount of the catalyst is 1% of the mass of the polycrystalline-like material B, air is introduced, the temperature is raised to 450 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the catalyst is naturally cooled to room temperature, and a 300-mesh sieve is used for obtaining the polycrystalline-like sodium ion anode material.
Example 3
The polycrystalline sodium ion-like positive electrode material of the embodiment comprises a core and a coating layer, wherein the chemical formula of the material in the core is Na 0.8 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The coating layer is Al 2 O 3 。
The preparation method of the polycrystalline sodium ion-like positive electrode material comprises the following steps:
(1) By NiO, mnO 2 ZnO and Na 2 CO 3 Raw materials, ni: mn: zn element mol ratio is 4:5:1, sodium and metal element mol ratio is 0.70:1, weighing the raw materials and uniformly mixing in a high-speed mixer to obtain a mixture A;
(2) Placing the mixture A in a box furnace for sintering, introducing air, heating to 800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, heating to 950 ℃ for preserving heat for 12 hours, naturally cooling to room temperature to obtain a block material, and sequentially carrying out rotary wheel grinding and jet milling on the block material, and crushing the block material into polycrystalline-like particles with an average size of 5.4 mu m to obtain the polycrystalline-like material A;
(3) Uniformly mixing the polycrystalline-like material A and NaOH in a high-speed mixer, wherein the adding amount of the NaOH is 3.71% of the mass of the polycrystalline-like material A to obtain a mixed material B, placing the mixed material B in a box-type furnace, then introducing air, heating to 700 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, naturally cooling to room temperature, and sieving with a 300-mesh sieve to obtain the polycrystalline-like material B;
(4) Mixing polycrystalline material B with Al 2 O 3 Mixing in a high-speed mixer, and placing into a box furnace, al 2 O 3 The adding amount of the catalyst is 1% of the mass of the polycrystalline-like material B, air is introduced, the temperature is raised to 450 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the catalyst is naturally cooled to room temperature, and a 300-mesh sieve is used for obtaining the polycrystalline-like sodium ion anode material.
Example 4
The polycrystalline sodium ion-like positive electrode material of the embodiment comprises a core and a coating layer, wherein the chemical formula of the material in the core is Na 0.85 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The coating layer is Al 2 O 3 。
The preparation method of the polycrystalline sodium ion-like positive electrode material comprises the following steps:
(1) By NiO, mnO 2 ZnO and Na 2 CO 3 Raw materials, ni: mn: zn element mol ratio is 4:5:1, sodium and metal element mol ratio is 0.80:1, weighing the raw materials and uniformly mixing in a high-speed mixer to obtain a mixture A;
(2) Placing the mixture A in a box furnace for sintering, introducing air, heating to 800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, heating to 950 ℃ for preserving heat for 12 hours, naturally cooling to room temperature to obtain a block material, and sequentially carrying out rotary wheel grinding and jet milling on the block material, and crushing the block material into polycrystalline-like particles with an average size of 4.9 mu m to obtain the polycrystalline-like material A;
(3) Mixing polycrystalline material A with Na 2 CO 3 Mixing uniformly in a high-speed mixer, na 2 CO 3 The adding amount of the catalyst is 2.43% of the mass of the polycrystalline material A to obtain a mixed material B, the mixed material B is placed in a box-type furnace, then air is introduced, the temperature is raised to 800 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the mixture is naturally cooled to the room temperature, and the mixture is sieved by a 300-mesh sieve to obtain the polycrystalline material B;
(4) Mixing polycrystalline material B with Al 2 O 3 Mixing in a high-speed mixer, and placing in a box furnace, al 2 O 3 The addition amount of the catalyst is 0.5 percent of the mass of the polycrystalline-like material B, air is introduced, the temperature is raised to 450 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the catalyst is naturally cooled to the room temperature, and the catalyst is sieved by a 300-mesh sieve, so that the polycrystalline-like sodium ion anode material is obtained.
Comparative example 1
The polycrystalline sodium ion-like positive electrode material of the embodiment comprises a core and a coating layer, wherein the chemical formula of the material in the core is Na 0.85 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The coating layer is Al 2 O 3 。
The preparation method of the polycrystalline sodium ion-like positive electrode material comprises the following steps:
(1) By NiO, mnO 2 ZnO and Na 2 CO 3 Raw materials, ni: mn: zn element mol ratio is 4:5:1, sodium and metal element mol ratio is 0.85:1, weighingThe raw materials are uniformly mixed in a high-speed mixer to obtain a mixture A;
(2) Placing the mixture A into a box furnace for sintering, introducing air, heating to 800 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, heating to 950 ℃ for preserving heat for 12 hours, naturally cooling to room temperature to obtain a block material, and sequentially carrying out rotary wheel grinding and jet milling on the block material, and crushing the block material into polycrystalline-like particles with an average size of 5.1 mu m to obtain the polycrystalline-like material A;
(3) Placing the polycrystalline material A into a box furnace for sintering, then introducing air, heating to 700 ℃ at a heating rate of 2.5 ℃/min, preserving heat for 6 hours, naturally cooling to room temperature, and sieving with a 300-mesh sieve to obtain a polycrystalline material B;
(4) Mixing polycrystalline material B with Al 2 O 3 Mixing in a high-speed mixer, sintering in a box furnace, and sintering Al 2 O 3 The adding amount of the catalyst is 1% of the mass of the polycrystalline-like material B, air is introduced, the temperature is raised to 450 ℃ at the heating rate of 2.5 ℃/min, the temperature is kept for 6 hours, the catalyst is naturally cooled to room temperature, and a 300-mesh sieve is used for obtaining the polycrystalline-like sodium ion anode material.
Fig. 1 shows an SEM image of the polycrystalline sodium ion-like positive electrode material prepared in example 1. As can be seen from FIG. 1, the sodium ion positive electrode material is a polycrystalline-like material, large particles are formed by a plurality of small particles, the average particle size of the large particles is 4-7um, the surface of the material is smooth, and no micro powder and low residual alkali content are caused.
Fig. 2 shows the XRD pattern of the polycrystalline sodium ion-like positive electrode material prepared in example 1. As can be seen from FIG. 2, XRD showed 16.5 DEG and 41 DEG peaks, which indicate that the structure is (003) and (104) characteristic diffraction peaks of the O3 phase layered oxide, belonging to a trigonal system, the space group is R-3m, the crystallinity is good, and no diffraction peaks of other crystalline phases appear.
Fig. 3 shows a first-pass charge-discharge curve of the polycrystalline sodium ion-like positive electrode material prepared in example 1. As can be seen from fig. 3, the first-turn capacity of the polycrystalline sodium ion positive electrode material is 133.2mAh/g, and the first charging efficiency is 90.5%; as can be seen from the charging curve of the material, the constant-current constant-voltage capacity is smaller, namely the polarization of the material is smaller; the curve is smoother in the charge and discharge process of the material, no obvious phase change platform appears, and the material also has good cycle performance.
The polycrystalline sodium ion-like cathode materials of examples 1 to 4 and comparative example 1 were measured for average particle diameter using a particle size analyzer, specific surface area using a microphone specific surface area analyzer 3020, and electrochemical performance test was performed at the same time, and the results are shown in table 1.
Electrochemical performance test: the polycrystalline sodium ion-like positive electrode material is used as an active substance, mixed with a binder PVDF and a conductive agent (Super-P) according to the mass ratio of 95:1.5:3.5, added with a proper amount of N-vinyl pyrrolidone as a solvent to be prepared into slurry, coated on an aluminum foil, and subjected to vacuum drying and rolling to prepare the negative electrode plate. Lithium metal was used as a counter electrode, and 1mol/L LiPF was used 6 And mixing the three components of mixed solvents according to the ratio of EC to DMC to emc=1:1:1 (v/v) to form an electrolyte, and adopting a polypropylene microporous membrane as a diaphragm to assemble the CR2032 button cell in a glove box filled with inert gas. The charge and discharge test of the button cell is carried out on a cell test system of blue electric power electronic Co Ltd in Wuhan city, the constant current charge and discharge of 0.1C is carried out to 0.01V at 25 ℃, then the constant current discharge of 0.02C is carried out to 0.005V, finally the constant current charge of 0.1C is carried out to 4.0V, the capacity charged to 4.0V is the first discharge specific capacity, the ratio of the discharge capacity and the charge capacity is the first charge and discharge efficiency, the corresponding discharge specific capacity of the 100 th turn is obtained after the cycle is carried out for 100 times, and the charge and discharge efficiency of the 100 th turn is calculated.
Table 1 test results
Figure BDA0004029360230000111
As can be seen from the results in Table 1, compared with comparative example 1, the polycrystalline sodium ion-like cathode materials of examples 1 to 4 have a better initial discharge specific capacity, initial charge-discharge efficiency and cycle performance, which indicates that the polycrystalline sodium ion-like cathode materials prepared in examples 1 to 4 have more sodium ions involved in the reaction and sodium ions can be back-embedded during the charge-discharge process, indicating that the power performance is better, i.e., the rate performance is better. After the material circulates for 100 circles, the specific capacity and the charge-discharge efficiency of the material are higher, which shows that the circulation performance is better, and the particles are tightly contacted, so that capacity water jump caused by the formation of a new interface is avoided.
In comparative example 1, since the second sodium salt was not added, the reinforcement and enhancement of the polycrystalline-like particles could not be performed, and the bonding between the particles was not tight, resulting in a decrease in the electrochemical properties.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified or substituted without departing from the spirit and scope of the technical solution of the present invention.

Claims (10)

1. The polycrystalline sodium ion-like positive electrode material is characterized by comprising a core and a coating layer, wherein the chemical formula of the material in the core is Na α Ni x Mn y M (1-x-y) O 2 Wherein, alpha is more than 0.60 and less than or equal to 1.0, x is more than 0 and less than or equal to 0.80,0, and y is more than 0 and less than or equal to 0.80; m is at least one of Zr, al, co, cu, sr, Y, ti, mg, K, fe, ca, li, mo, B, sn, si, nb, zn, W, tc and Ru, and the coating layer material is oxide.
2. The polycrystalline sodium ion-like positive electrode material according to claim 1, wherein the oxide is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them.
3. The polycrystalline sodium ion-like positive electrode material according to claim 2, which is characterized in thatCharacterized in that the chemical formula of the material in the inner core is Na 0.85 Ni 0.4 Mn 0.5 Zn 0.1 O 2 The material in the coating layer is Al 2 O 3 。
4. The preparation method of the polycrystalline sodium ion-like positive electrode material is characterized by comprising the following steps:
(1) NiO and MnO are mixed according to the formula amount 2 Mixing the doping agent with the first sodium salt to obtain a mixture A;
(2) Sintering the mixture A for the first time, and then crushing to obtain a polycrystalline-like material A, wherein the average particle size of the polycrystalline-like material A is controlled to be 4-7um through crushing;
(3) Mixing the polycrystalline-like material A with a second sodium salt to obtain a mixed material B, and then performing secondary sintering to obtain the polycrystalline-like material B;
(4) And mixing the polycrystalline material B with a coating agent, and performing third sintering to obtain the polycrystalline sodium ion anode material.
5. The method for preparing a polycrystalline sodium ion-like positive electrode material according to claim 4, wherein the dopant is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them.
6. The method for preparing a polycrystalline sodium ion-like positive electrode material according to claim 4, wherein the first sodium salt is NaOH or NaNO 3 、Na 2 CO 3 Or CH (CH) 3 At least one of COONa; the second sodium salt is NaOH or NaNO 3 、Na 2 CO 3 Or CH (CH) 3 At least one of COONa.
7. The method for preparing a polycrystalline sodium ion-like positive electrode material according to claim 4, wherein the coating agent is ZrO 2 、Al 2 O 3 、Co 3 O 4 、CuO、SrO、Y 2 O 3 、MnO 2 、TiO 2 、MgO、K 2 O、Fe 2 O 3 、CaO、Li 2 O、MoO 2 、B 2 O 3 、SnO 2 、SiO 2 、Nb 2 O 5 、ZnO、WO 3 、Tc 2 O 7 And RuO (Ruo) 4 At least one of them.
8. The method for preparing a polycrystalline sodium ion-like positive electrode material according to claim 4, wherein the first sintering is performed at 600 ℃ to 850 ℃ for 3 to 8 hours, and then at 850 to 950 ℃ for 8 to 16 hours;
the second sintering is carried out for 4-12 hours under the condition that the temperature is 400-800 ℃;
the third sintering is carried out under the condition of 300-600 ℃ for 4-8 hours.
9. The method for preparing a polycrystalline sodium ion-like positive electrode material according to claim 4, wherein the addition amount of the second sodium salt is 1-10% of the mass of the polycrystalline-like material A.
10. Use of the polycrystalline sodium ion-like positive electrode material according to any one of claims 1 to 3 or the polycrystalline sodium ion-like positive electrode material prepared by the method for preparing the polycrystalline sodium ion-like positive electrode material according to any one of claims 4 to 9 in a sodium ion battery.
CN202211743472.7A 2022-12-30 2022-12-30 Polycrystalline sodium ion-like positive electrode material, and preparation method and application thereof Pending CN116031380A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117012948A (en) * 2023-09-27 2023-11-07 宁波容百新能源科技股份有限公司 Positive electrode material, preparation method thereof and sodium ion battery
CN117497728A (en) * 2023-12-04 2024-02-02 湖南美特新材料科技有限公司 Sodium ion battery positive electrode material and preparation method thereof

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117012948A (en) * 2023-09-27 2023-11-07 宁波容百新能源科技股份有限公司 Positive electrode material, preparation method thereof and sodium ion battery
CN117497728A (en) * 2023-12-04 2024-02-02 湖南美特新材料科技有限公司 Sodium ion battery positive electrode material and preparation method thereof
CN117497728B (en) * 2023-12-04 2024-06-11 湖南美特新材料科技有限公司 Sodium ion battery positive electrode material and preparation method thereof

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