Positive electrode material, and preparation method therefor and use thereof

Abstract

A positive electrode material, and a preparation method therefor and the use thereof. The positive electrode material comprises a positive electrode base material and a coating layer that coats the surface of the positive electrode base material. The positive electrode base material has a general chemical formula of AaMexMnyO2, wherein A comprises Na and / or Li; 0.6≤a≤1, 0.1≤x≤0.4, 0.2≤y≤0.6, and x+y=1; and Me comprises a transition metal element. The coating layer comprises sodium niobate. The distribution of elements in the positive electrode material is uniform; and after coating with sodium niobate, not only is the effect of isolating the positive electrode material from an electrolyte achieved, but the dynamic performance and safety performance of the positive electrode material are also improved.

Description

A positive electrode material and its preparation method and use Technical Field

[0001] The present application belongs to the technical field of batteries (sodium ions and / or lithium ions), and relates to a positive electrode material, a preparation method thereof, and uses thereof. Background Art

[0002] With the depletion of non-renewable resources and the resulting severe environmental pollution from the use of traditional energy sources, there is an urgent need to research and develop new energy and energy storage technologies. Lithium-ion batteries are a new generation of secondary batteries, offering advantages such as high specific capacity, excellent cycle performance, low self-discharge, and excellent safety. They have been applied in electronics, new energy vehicles, aerospace, and other fields. Sodium-ion batteries have abundant reserves and high battery safety. Their potential for application in new energy vehicle power batteries and large-scale energy storage has led many countries to focus on the development of sodium-ion battery technology. The positive electrode material is one of the key factors affecting battery performance.

[0003] Currently, the commonly used methods for preparing sodium and lithium battery positive electrode materials include: sol-gel method, spray drying method, co-precipitation method, solid phase method, hydrothermal method, etc.

[0004] Co-precipitation and high-temperature solid-phase methods are currently the preferred methods for preparing positive electrode materials. The particles prepared by the co-precipitation method are evenly distributed and can achieve uniform mixing at the atomic level, but the process is complicated and tedious, and the reaction conditions need to be precisely controlled to keep the physical and chemical indicators of the materials consistent; the high-temperature solid-phase sintering process is simple, but it is difficult to achieve atomic-level mixing of the raw materials, which will cause local enrichment and low discharge specific capacity; secondly, the process morphology of the high-temperature solid-phase preparation is irregular, the particle size is uneven, the degree of raw material mixing is limited, and a higher heat treatment temperature and a longer heat treatment time are required.

[0005] Therefore, how to obtain positive electrode materials for sodium ion batteries or lithium ion batteries with uniform particle size, uniform element distribution and better performance is a technical problem that needs to be solved urgently.

[0006] Summary of the Invention

[0007] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0008] To address the shortcomings of the prior art, the present application aims to provide a cathode material, its preparation method, and its use. The cathode material provided in this application has a uniform element distribution. After being coated with sodium niobate, it not only isolates the cathode material from the electrolyte but also improves the kinetic and safety performance of the cathode material.

[0009] To achieve this goal, this application adopts the following technical solutions:

[0010] In a first aspect, the present application provides a positive electrode material, the positive electrode material comprising a positive electrode base material and a coating layer coated on the surface of the positive electrode base material; the chemical formula of the positive electrode base material is A a Me x Mn y O2, wherein A includes Na and / or Li, 0.6≤a≤1, 0.1≤x≤0.4, 0.2≤y≤0.6, x+y=1, and Me includes a transition metal element; and the coating layer includes sodium niobate.

[0011] For example, a may be 0.6, 0.7, 0.8, 0.9 or 1, etc.; x may be 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4, etc.; y may be 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6, etc.

[0012] The positive electrode material provided in the present application has a uniform distribution of elements in the base material, a uniform particle size, and a more stable structure. After being coated with sodium niobate, it can not only avoid direct contact between the positive electrode base material and the electrolyte, but also improve the surface stability of the electrode material, thereby facilitating the improvement of the cycle stability of the positive electrode material; more importantly, the stress changes brought about by the changes in the crystal microstructure of the positive electrode base material during the electrochemical cycle are utilized to generate a piezoelectric potential in the surface-coated sodium niobate, thereby effectively improving the interfacial ion diffusion capacity and further improving the kinetic performance of the battery; in addition, the uniform sodium niobate coating layer has a specific Curie temperature, which can effectively improve the thermal safety of the positive electrode active material to varying degrees and reduce safety hazards.

[0013] In the present application, the matrix material can be a sodium ion positive electrode material or a lithium ion positive electrode material, and can be adaptively adjusted according to actual needs; and if it does not contain a sodium niobate coating layer, it will not be possible to inhibit the growth of the SEI film, resulting in degradation of the material surface structure and affecting the stability of the electrode material.

[0014] In one embodiment, the A a Me x Mn y In O2, Me includes any one of Ni, Co, Fe, Cu, Al, Mg, Zr, Ti or Ca, or a combination of at least two thereof.

[0015] In one embodiment, the coating amount of the coating layer is 1-5% of the mass of the positive electrode base material, for example, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5%.

[0016] In one embodiment, the particle size of the sodium niobate is nanometer scale.

[0017] In the present application, the sodium niobate with nanometer-scale particle size has a tighter coating and a denser coating layer, which can better improve the performance of the positive electrode material.

[0018] In a second aspect, the present application provides a method for preparing the positive electrode material according to the first aspect, the preparation method comprising the following steps:

[0019] Mixing the positive electrode precursor, the A source and the coating source, and sintering to obtain the positive electrode material;

[0020] Wherein, the A source includes a lithium source and / or a sodium source, and the coating source includes sodium niobate.

[0021] The preparation method provided in this application is simple to operate and suitable for large-scale production.

[0022] In one embodiment, the method for preparing the positive electrode precursor includes:

[0023] The precursor salt solution is ultrasonically atomized, and the metal elements in the precursor salt solution are mixed with A a Me x Mn y The metal elements other than the non-A elements in O2 are kept consistent, and then the atomized precursor salt solution is spray pyrolyzed to obtain a positive electrode precursor.

[0024] In the present application, the positive electrode precursor material is prepared by spray pyrolysis, which has a simple preparation process and obtains particles with smaller and more uniform particle size. At the same time, the distribution of metal elements in the positive electrode precursor is more uniform, the element segregation phenomenon in the subsequent sintering process will be significantly reduced, and the contact with the coating layer will be closer.

[0025] In one embodiment, the concentration of total metal ions in the precursor salt solution is 80-130 g / L, for example, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L or 130 g / L.

[0026] In one embodiment, the atomized precursor salt solution is spray pyrolyzed using a carrier gas.

[0027] In one embodiment, the carrier gas comprises oxygen and / or air.

[0028] In one embodiment, the flow rate of the carrier gas is 3 to 8 L / min, for example, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min or 8 L / min.

[0029] In one embodiment, the spray pyrolysis temperature is 700-950°C, for example, 700°C, 750°C, 800°C, 850°C, 900°C or 950°C.

[0030] In one embodiment, the preparation method of sodium niobate comprises:

[0031] A sodium source, an alkali source, a niobium source and a solvent are mixed to obtain a mixed solution, the mixed solution is then ultrasonically atomized, and the atomized mixed solution is spray-pyrolyzed to obtain sodium niobate.

[0032] In the present application, the sodium niobate prepared by spray pyrolysis has a particle size at the nanometer level. When coated on the surface of the positive electrode matrix material, it is more dense. In the sintering process after mixing, the coating of the nano-scale particles is further strengthened, and the contact with the positive electrode matrix material is closer, which not only has a good coating effect, but also better exerts its own piezoelectric properties. If the sodium niobate is prepared by a conventional high-temperature solid-phase method, it is easy to agglomerate during the sintering process and has high energy consumption, which affects the dispersion of the material particle size.

[0033] In one embodiment, the sodium source comprises sodium carbonate.

[0034] In one embodiment, the alkalinity source comprises sodium hydroxide.

[0035] In one embodiment, the niobium source comprises niobium pentoxide.

[0036] In one embodiment, the mixing includes: mixing the sodium source, the alkali source and the solvent once, and then adding the niobium source and mixing them again to obtain a mixed solution.

[0037] In one embodiment, the time for the primary mixing is 20 to 60 min, for example, 20 min, 30 min, 40 min, 50 min or 60 min.

[0038] In one embodiment, the secondary mixing time is 10 to 30 minutes, such as 10 minutes, 20 minutes or 30 minutes.

[0039] In one embodiment, the spray pyrolysis temperature is 800-1100°C, for example, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C or 1100°C.

[0040] In this application, the positive electrode precursor and sodium niobate are both prepared by spray pyrolysis, which can better control the uniform mixing of elements, the particle size, morphology, crystallinity and other properties of the material. The synthesis process is simple, easy to control, and can be produced continuously and quickly.

[0041] In one embodiment, the sintering is performed in an oxygen-containing atmosphere.

[0042] In the present application, sintering can be divided into a one-stage sintering process or a two-stage sintering process.

[0043] In one embodiment, the sintering heating rate is 2 to 8°C / min, for example, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min or 8°C / min.

[0044] In one embodiment, the sintering temperature is 400-1000°C, for example, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C or 1000°C.

[0045] In one embodiment, the sintering time is 5 to 30 hours, for example, 5 hours, 10 hours, 15 hours, 20 hours, 25 hours or 30 hours.

[0046] As an optional technical solution of this application, the preparation method includes the following steps:

[0047] The precursor salt solution is ultrasonically atomized, and the metal elements in the precursor salt solution are mixed with A a Me x Mn y The metal elements other than the A elements in O2 are kept consistent, and the atomized precursor salt solution is spray-pyrolyzed at 700-950°C using oxygen at a flow rate of 3-8 L / min to obtain a cathode precursor;

[0048] A sodium source, an alkali source, and a solvent are mixed for 20 to 60 minutes, and then a niobium source is added and mixed for a second time for 10 to 30 minutes to obtain a mixed solution. The mixed solution is then ultrasonically atomized, and the atomized mixed solution is spray pyrolyzed at 800 to 1100° C. to obtain sodium niobate.

[0049] Mixing the positive electrode precursor, source A and coating source, and sintering at 400-1000° C. for 5-30 hours to obtain the positive electrode material;

[0050] Wherein, the A source includes a lithium source and / or a sodium source, and the coating source includes sodium niobate.

[0051] In a third aspect, the present application further provides a battery, comprising the positive electrode material as described in the first aspect.

[0052] In one embodiment, the battery comprises a lithium ion battery and / or a sodium ion battery.

[0053] Compared with the prior art, this application has the following beneficial effects:

[0054] The positive electrode material provided in the present application has a uniform distribution of elements in the base material, a uniform particle size, and a more stable structure. After being coated with sodium niobate, it can not only avoid direct contact between the positive electrode base material and the electrolyte, but also improve the surface stability of the electrode material, thereby facilitating the improvement of the cycle stability of the positive electrode material; more importantly, the stress changes brought about by the changes in the crystal microstructure of the positive electrode base material during the electrochemical cycle are utilized to generate a piezoelectric potential in the surface-coated sodium niobate, thereby effectively improving the interfacial ion diffusion capacity and further improving the kinetic performance of the battery; in addition, the uniform sodium niobate coating layer has a specific Curie temperature, which can effectively improve the thermal safety of the positive electrode active material to varying degrees and reduce safety hazards.

[0055] Still other aspects will become apparent upon reading and understanding the detailed description. DETAILED DESCRIPTION

[0056] The technical solution of the present application is further illustrated below by specific examples. Those skilled in the art should understand that the examples are only for facilitating understanding of the present application and should not be regarded as specific limitations of the present application.

[0057] Example 1

[0058] This embodiment provides a positive electrode material, the positive electrode material includes a base material LiNi 0.8 Co 0.1 Mn 0.1 O2 and a NaNbO3 coating layer coated on the surface of the base material; the chemical formula of the positive electrode material is LiNi 0.8 Co 0.1 Mn 0.1 O2@NaNbO3, the particle size of sodium niobate is nanometer scale.

[0059] The specific preparation steps of the positive electrode material are as follows:

[0060] (1) preparing a nickel-cobalt-manganese oxide precursor: preparing a nickel-cobalt-manganese sulfate solution (a molar ratio of Ni, Co, and Mn of 8:1:1) with a total metal ion concentration of 100 g / L, subjecting the nickel-cobalt-manganese sulfate solution to ultrasonic atomization treatment, and then feeding the atomized precursor solution into a spray pyrolysis furnace with an oxygen flow rate of 4 L / min for pyrolysis reaction at a pyrolysis temperature of 700° C. to obtain a nickel-cobalt-manganese oxide precursor;

[0061] Preparation of sodium niobate: 0.5 mol sodium carbonate and 0.1 mol sodium hydroxide were added to deionized water and heated with stirring for 40 minutes. After complete dissolution, 2 g of Nb2O5 was added to the mixed solution and heated with stirring for 20 minutes to uniformly mix to form a milky white mixed solution. The mixed solution was then ultrasonically atomized and the atomized precursor solution was then fed into a spray pyrolysis furnace with oxygen at a flow rate of 4 L / min for pyrolysis at 1100°C to obtain nano-sized sodium niobate.

[0062] (2) Nickel cobalt manganese oxide precursor, sodium niobate and lithium hydroxide were mixed and ground evenly according to the total metal molar ratio of nickel, cobalt and manganese to lithium molar ratio of 1:1.1, and then sintered at high temperature. Two stages of sintering were carried out under an oxygen atmosphere. The first stage of sintering was heated at a rate of 3°C / min and kept at 580°C for 10 hours; the second stage of sintering was heated at a rate of 3°C / min and kept at 850°C for 2 hours to obtain LiNi 0.8 Co 0.1 Mn 0.1 O2@NaNbO3.

[0063] Example 2

[0064] The difference between this embodiment and embodiment 1 is that the sodium niobate in this embodiment is a micron-sized sheet structure, and the preparation method is as follows:

[0065] 1) First press Bi 2.5 Na 3.5 Nb5O 18 Weigh analytically pure Bi2O 34 0.66 g, analytically pure Na2CO3 12.95 g, analytically pure Nb2O5 46.39 g, were mixed together, added with anhydrous ethanol, and ball-milled for 4 hours, followed by drying and sieving; then 200 g of the ball-milled NaCl salt was added; the weight ratio of NaCl salt to the above mixture was 2:1; the ball-milling was continued for another hour, followed by drying and sieving;

[0066] 2) The mixed raw materials are placed in an alumina crucible, heated to 900°C, kept warm for 2 hours, then heated to 1100°C, kept warm for 4 hours, and the molten salt is reacted to synthesize Bi 2.5 Na 3.5 Nb5O 18 The synthesized product was washed with deionized water to remove the residual NaCl salt and dried to obtain a lamellar structure Bi 2.5 Na 3.5 Nb5O 18 Single crystal particles.

[0067] 3) According to Na2CO3 and Bi 2.5 Na3.5 Nb5O 18 The molar ratio is 1:1, and the NaCl salt and (Na2CO3+Bi 2.5 Na 3.5 Nb5O 18 ) The weight ratio of the mixture is 2:1 to calculate the chemical ratio, that is, weigh 197.27 grams of NaCl and 7.15 grams of Na2CO3. The above-mentioned synthetic product Bi 2.5 Na 3.5 Nb5O 18 94.48g of single crystal particles; first, mix the NaCl and Na2CO3 mixture and ball mill, add anhydrous ethanol at the same time, and ball mill for 4 hours; then add Bi 2.5 Na 3.5 Nb5O 18 The single crystal granules are then stirred, dried and sieved.

[0068] 4) The mixture was again placed in an alumina crucible, heated to 950°C, and held for 4 hours to synthesize flaky NaNbO3 single crystal particles using a topochemical reaction, followed by furnace cooling to room temperature; the reaction product was washed with deionized water, then acid-washed with HNO3, and repeatedly washed with deionized water to remove residues, and then dried to obtain pure flaky NaNbO3 single crystal particles.

[0069] The rest of the preparation methods and parameters were the same as those in Example 1.

[0070] Example 3

[0071] The difference between this embodiment and embodiment 1 is that the positive electrode precursor material in step (1) of this embodiment is a nickel-cobalt-manganese hydroxide precursor material, and the preparation method is:

[0072] Nickel cobalt manganese sulfate solution (the molar ratio of Ni, Co and Mn is 8:1:1), ammonia solution and sodium hydroxide solution are added in parallel, and a coprecipitation reaction is carried out at a reaction temperature of 40°C under the condition of pH 10.8 to obtain a nickel cobalt manganese hydroxide precursor material.

[0073] The rest of the preparation methods and parameters were the same as those in Example 1.

[0074] Example 4

[0075] This embodiment provides a positive electrode material, the positive electrode material includes a base material NaMn 0.31 Cu 0.34 Fe 0.35 O2 and a NaNbO3 coating layer coated on the surface of the base material; the chemical formula of the positive electrode material is NaMn 0.31 Cu 0.34 Fe 0.35O2@NaNbO3, the particle size of sodium niobate is nanometer scale.

[0076] The specific preparation steps of the positive electrode material are as follows:

[0077] (1) Preparing an iron-copper-manganese oxide precursor: preparing an iron-copper-manganese sulfate solution (the molar ratio of Mn, Cu, and Fe is 0.31:0.34:0.35) with a total metal ion concentration of 100 g / L, subjecting the iron-copper-manganese sulfate solution to ultrasonic atomization treatment, and then feeding the atomized precursor solution into a spray pyrolysis furnace with oxygen at a flow rate of 5 L / min for pyrolysis reaction at a pyrolysis temperature of 800°C to obtain an iron-copper-manganese oxide precursor;

[0078] Preparation of sodium niobate: 0.5 mol sodium carbonate and 0.1 mol sodium hydroxide were added to deionized water and heated with stirring for 30 minutes. After complete dissolution, 2 g of Nb2O5 was added to the mixed solution and heated with stirring for 10 minutes to uniformly mix to form a milky white mixed solution. The mixed solution was then ultrasonically atomized and the atomized precursor solution was then fed into a spray pyrolysis furnace with oxygen at a flow rate of 4 L / min for pyrolysis at 1050°C to obtain nano-sized sodium niobate.

[0079] (2) The iron-copper-manganese oxide precursor, sodium niobate and sodium carbonate were mixed and ground evenly according to the total metal molar ratio of iron, copper and manganese to sodium molar ratio of 1:1.05, and then sintered at high temperature. The sintering was carried out in an oxygen atmosphere at a heating rate of 5°C / min and the sintering temperature was kept at 900°C for 24 hours to obtain NaMn 0.31 Cu 0.34 Fe 0.35 O2@NaNbO3.

[0080] Example 5

[0081] The difference between this embodiment and embodiment 4 is that the sodium niobate in this embodiment is a micron-scale flaky structure, and the preparation method of the sodium niobate is the same as that in embodiment 2.

[0082] The remaining preparation methods and parameters were consistent with those in Example 4.

[0083] Comparative Example 1

[0084] The difference between this comparative example and Example 1 is that the positive electrode material provided in this comparative example does not contain a sodium niobate coating layer, and the positive electrode material is a positive electrode matrix material.

[0085] In the preparation method, the preparation and coating of sodium niobate are not performed.

[0086] The rest of the preparation methods and parameters were the same as those in Example 1.

[0087] Comparative Example 2

[0088] The difference between this comparative example and Example 4 is that the positive electrode material provided in this comparative example does not contain a sodium niobate coating layer, and the positive electrode material is a positive electrode matrix material.

[0089] In the preparation method, the preparation and coating of sodium niobate are not performed.

[0090] The remaining preparation methods and parameters were consistent with those in Example 4.

[0091] A 7% polyvinylidene fluoride solution was prepared using N-methylpyrrolidone as a solvent. The positive electrode materials provided in Examples 1-3 and Comparative Example 1, polyvinylidene fluoride, and conductive carbon black were mixed evenly in a mass ratio of 95:2:3. The mixture was then applied to an aluminum foil. The coated electrode was placed in a vacuum drying oven at 90°C and dried for 4 hours. The electrode was then rolled to a surface density of 4-7 mg / cm 2 For standby use, lithium metal sheet as counter electrode, 1 mol / LLiPF6 three-component mixed solvent with EC:DMC:EMC=1:1:1 (volume ratio) as electrolyte, and then assembled into 2032 button cells in an argon-filled glove box.

[0092] The electrochemical performance tests were performed on the lithium-ion batteries provided in Examples 1-3 and Comparative Example 1. The test conditions were as follows: Cycle performance test conditions: at 25°C, 1C / 1C cycle for 200 cycles to detect capacity retention (cycle performance). The test results are shown in Table 1.

[0093] Table 1

[0094] A 7% polyvinylidene fluoride solution was prepared using N-methylpyrrolidone as a solvent. The sodium ion positive electrode materials provided in Examples 4-5 and Comparative Example 2, polyvinylidene fluoride, and conductive carbon black were mixed evenly in a mass ratio of 80:10:10 and applied to aluminum foil. The coated electrode was placed in a vacuum drying oven at 90°C and dried for 4 hours. The electrode was then rolled to a surface density of 4-7 mg / cm 2 For standby use, a sodium metal sheet was used as the counter electrode, and a 1 mol / L NaPF6 solution in diethylene glycol dimethyl ether was used as the electrolyte, and then assembled into a 2032-type button cell in an argon-filled glove box.

[0095] The sodium ion batteries provided in Examples 4-5 and Comparative Example 2 were subjected to electrochemical performance tests. The test conditions were: a cycle test was performed in the voltage range of 2-4.2 V: the capacity retention rate was obtained by cycling at 0.5C / 0.5C for 100 cycles. The test results are shown in Table 2.

[0096] Table 2

[0097] Combining Table 1 and Table 2, we can conclude that:

[0098] It can be seen from the data results of Examples 1, 2, 4 and 5 that when sodium niobate is prepared by a method other than spray pyrolysis, the coating effect is poor and the cycle performance is reduced.

[0099] From the data results of Examples 1, 2 and 3, it can be seen that in the positive electrode material provided in this application, the positive electrode precursor and sodium niobate are both prepared by spray pyrolysis, and the two work together to achieve improved cycle stability.

[0100] From the data results of Example 1 and Comparative Example 1, and Example 4 and Comparative Example 2, it can be seen that, whether it is a lithium-ion positive electrode material or a sodium-ion positive electrode material, the problem of poor cycle stability of the positive electrode material cannot be solved without coating the surface with sodium niobate.

[0101] In summary, the present application prepares the positive electrode precursor material and sodium niobate material by spray pyrolysis, and then coats the material with sodium niobate. The resulting positive electrode material has uniform element distribution, small particle size, dense coating layer, and excellent coating effect. The elements in the matrix material are uniformly distributed, the particle size is uniform, and the structure is more stable. After coating with sodium niobate, it can not only avoid direct contact between the positive electrode matrix material and the electrolyte, but also improve the surface stability of the electrode material, thereby helping to improve the cycle stability of the positive electrode material. More importantly, the stress changes brought about by the changes in the crystal microstructure of the positive electrode matrix material during the electrochemical cycle are utilized to generate a piezoelectric potential on the surface-coated sodium niobate, thereby effectively improving the interfacial ion diffusion capacity and further improving the kinetic performance of the battery. In addition, the uniform sodium niobate coating layer has a specific Curie temperature, which can effectively improve the thermal safety of the positive electrode active material to varying degrees and reduce safety hazards.

[0102] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of this application. It should be understood that the above is only a specific embodiment of this application and is not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A positive electrode material, comprising a positive electrode base material and a coating layer coated on the surface of the positive electrode base material; the chemical formula of the positive electrode base material is A a Me x Mn y O2, wherein A includes Na and / or Li, 0.6≤a≤1, 0.1≤x≤0.4, 0.2≤y≤0.6, x+y=1, and Me includes a transition metal element; and the coating layer includes sodium niobate.

2. The positive electrode material according to claim 1, wherein The A a Me x Mn y In O2, Me includes any one of Ni, Co, Fe, Cu, Al, Mg, Zr, Ti or Ca, or a combination of at least two thereof.

3. The positive electrode material according to claim 1 or 2, wherein The coating amount of the coating layer is 1 to 5% of the mass of the positive electrode base material; Optionally, the particle size of the sodium niobate is nanometer scale.

4. A method for preparing the positive electrode material according to any one of claims 1 to 3, comprising the following steps: Mixing a positive electrode precursor, a source A and a coating source, and sintering to obtain the positive electrode material; Wherein, the A source includes a lithium source and / or a sodium source, and the coating source includes sodium niobate.

5. The method for preparing the positive electrode material according to claim 4, wherein: The preparation method of the positive electrode precursor comprises: The precursor salt solution is ultrasonically atomized, and the metal elements in the precursor salt solution are reacted with A a Me x Mn y The metal elements other than the A elements in O2 are kept consistent, and then the atomized precursor salt solution is spray pyrolyzed to obtain a positive electrode precursor.

6. The method for preparing the positive electrode material according to claim 5, wherein: The concentration of total metal ions in the precursor salt solution is 80 to 130 g / L; Optionally, the atomized precursor salt solution is spray pyrolyzed using a carrier gas; Optionally, the carrier gas comprises oxygen and / or air; Optionally, the flow rate of the carrier gas is 3 to 8 L / min; Optionally, the spray pyrolysis temperature is 700-950°C.

7. The method for preparing a positive electrode material according to any one of claims 4 to 6, wherein: The preparation method of sodium niobate comprises: A sodium source, an alkali source, a niobium source and a solvent are mixed to obtain a mixed solution, and then the mixed solution is ultrasonically atomized, and the atomized mixed solution is spray-pyrolyzed to obtain sodium niobate; Optionally, the sodium source comprises sodium carbonate; Optionally, the alkali source comprises sodium hydroxide; Optionally, the niobium source comprises niobium pentoxide; Optionally, the mixing includes: mixing the sodium source, the alkali source and the solvent once, and then adding the niobium source for secondary mixing to obtain a mixed solution; Optionally, the time of the first mixing is 20 to 60 minutes; Optionally, the secondary mixing time is 10 to 30 minutes; Optionally, the spray pyrolysis temperature is 800-1100°C.

8. The method for preparing a positive electrode material according to any one of claims 4 to 7, wherein: The sintering is carried out in an oxygen-containing atmosphere; Optionally, the heating rate of the sintering is 2 to 8°C / min; Optionally, the sintering temperature is 400-1000°C; Optionally, the sintering time is 5 to 30 hours.

9. The method for preparing a positive electrode material according to any one of claims 4 to 8, wherein: The preparation method comprises the following steps: The precursor salt solution is ultrasonically atomized, and the metal elements in the precursor salt solution are reacted with A a Me x Mn y The metal elements other than the non-A elements in O2 are kept consistent, and the atomized precursor salt solution is spray-pyrolyzed at 700-950°C using oxygen at a flow rate of 3-8 L / min to obtain a positive electrode precursor; The sodium source, the alkali source and the solvent are mixed for 20 to 60 minutes, and then the niobium source is added and mixed for 10 to 30 minutes to obtain a mixed solution, and then the mixed solution is ultrasonically atomized, and the atomized mixed solution is spray-pyrolyzed at 800 to 1100° C. to obtain sodium niobate; Mixing the positive electrode precursor, the A source and the coating source, and sintering at 400 to 1000° C. for 5 to 30 hours to obtain the positive electrode material; Wherein, the A source includes a lithium source and / or a sodium source, and the coating source includes sodium niobate.

10. A battery comprising the positive electrode material according to any one of claims 1 to 3; Optionally, the battery comprises a lithium ion battery and / or a sodium ion battery.

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