Sodium ion positive electrode material and its preparation method and application

Abstract

The present invention relates to the technical field of sodium ion batteries, and in particular to a sodium ion positive electrode material, a preparation method thereof, and an application thereof. The preparation method of the sodium ion positive electrode material comprises: S1: mixing a nickel source, an iron source, a manganese source, other metal sources, and a sodium source, and then performing a first calcination treatment to obtain an intermediate product; S2: mixing the intermediate product and a coating agent, and then performing a second calcination treatment to obtain the sodium ion positive electrode material; the coating agent comprises a first coating agent and / or a second coating agent; the first coating agent comprises a nickel source; the second coating agent comprises a zinc source. The sodium ion positive electrode material provided by the present invention, and its preparation method and application, can significantly improve the conductivity of the positive electrode material by optimizing the coating means, improve the cycle retention rate, and improve the charge and discharge performance; ultimately, a high-capacity, long-cycle sodium ion positive electrode material is obtained.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a sodium-ion cathode material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries dominate the market for portable electronics and electric vehicles, but their application in large-scale energy storage is limited due to the low reserves and high price of lithium resources. Sodium-ion batteries, with similar chemical properties to lithium-ion batteries and abundant sodium resources, are considered a promising alternative in large-scale energy storage applications such as smart grids.

[0003] Among numerous sodium-ion cathode materials, layered transition metal oxides are considered the most promising due to their high theoretical capacity and ease of synthesis. However, because sodium ions have a large radius, significant volume changes and phase transitions occur during insertion / extraction, leading to interlayer delamination and structural collapse, resulting in decreased cycle retention. Therefore, reducing volumetric strain during cycling and optimizing the interface between the cathode material and the electrolyte are crucial for layered transition metal oxides.

[0004] Surface coating is a common method for interfacial modification of layered oxides. Common industrial coatings are metal oxides, such as Al2O3, TiO2, and ZrO2, which can effectively suppress interfacial side reactions and volumetric strain. However, due to their electrochemical inertness, these coatings suffer significant losses in charge and discharge capacity.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a sodium-ion cathode material, its preparation method, and its application, thereby obtaining a high-capacity, long-cycle sodium-ion cathode material.

[0007] In a first aspect, the present invention provides a method for preparing a sodium ion cathode material, comprising the following steps.

[0008] S1: Mix nickel source, iron source, manganese source, other metal source and sodium source, and then perform a first calcination treatment to obtain intermediate product;

[0009] S2: The intermediate product and the coating agent are mixed, and then subjected to a second calcination treatment to obtain the sodium ion cathode material; the coating agent includes a first coating agent and / or a second coating agent; the first coating agent includes a nickel source; the second coating agent includes a zinc source.

[0010] According to a method for preparing a sodium-ion cathode material provided by the present invention, the coating agent includes a first coating agent and a second coating agent; wherein the molar amount a of the first coating agent and the molar amount b of the second coating agent satisfy the following relationship: 0.7≤a≤0.9, 0.1≤b≤0.3, a+b=1.

[0011] According to the method for preparing a sodium-ion cathode material provided by the present invention, the amount of the coating agent is 0.2-2 wt%, based on the mass of the intermediate product; preferably, the amount of the coating agent is 0.3-0.7 wt%.

[0012] According to a method for preparing a sodium-ion cathode material provided by the present invention, during the first calcination treatment, the calcination temperature is controlled at 800-1200 degrees Celsius; and / or, during the second calcination treatment, the calcination temperature is controlled at 700-850 degrees Celsius.

[0013] According to a method for preparing a sodium-ion cathode material provided by the present invention, the first coating agent includes nickel oxide and / or nickel hydroxide; the second coating agent includes zinc oxide and / or zinc hydroxide.

[0014] According to a method for preparing a sodium-ion cathode material provided by the present invention, the other metal sources include one or more of aluminum, titanium, calcium, zirconium, and zinc sources; preferably, the aluminum source includes aluminum oxide; the titanium source includes titanium oxide; and the calcium source includes calcium oxide.

[0015] According to the method for preparing a sodium-ion cathode material provided by the present invention, the amount of other metal sources is 0.1 to 10 wt%, based on the total mass of the nickel source, iron source and manganese source.

[0016] According to a method for preparing a sodium-ion cathode material provided by the present invention, the ratio of the total molar amount of nickel in the nickel source, iron in the iron source, manganese in the manganese source, and other metal elements in the metal source to the molar amount of sodium in the sodium source is 1:(0.6~1.1).

[0017] According to a method for preparing a sodium-ion cathode material provided by the present invention, the nickel source includes one or more of nickel oxide, nickel hydroxide, and nickel acetate; the iron source includes ferric oxide and / or ferric oxide; the manganese source includes one or more of manganese dioxide, manganese tetroxide, and manganese acetate; the sodium source includes one or more of anhydrous sodium carbonate, sodium hydroxide, sodium acetate, and sodium sulfate; preferably, the molar ratio of the nickel source, the iron source, and the manganese source is (0.2-0.5):(0.2-0.5):(0.2-0.5).

[0018] Secondly, the present invention provides a sodium ion cathode material, which is prepared by the above-mentioned method for preparing sodium ion cathode materials.

[0019] Thirdly, the present invention provides a sodium-ion battery comprising the aforementioned sodium-ion positive electrode material.

[0020] The sodium-ion cathode material, its preparation method, and its application provided by this invention can significantly improve the conductivity of the cathode material and enhance the cycle retention rate while improving charge-discharge performance by optimizing the coating method; ultimately, a high-capacity, long-cycle sodium-ion cathode material is obtained. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a SEM image of the sodium ion cathode material prepared in Example 1 of the present invention.

[0023] Figure 2 This is an XRD image of the sodium-ion cathode material prepared in Example 1 of the present invention.

[0024] Figure 3 These are the coin cell cycle data of the sodium-ion cathode materials prepared in Example 1 and Comparative Example 1 provided by the present invention.

[0025] Figure 4 These are the rate discharge data of the coin cell half-cells of sodium ion cathode materials provided in Example 1 and Comparative Example 1 of this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0027] To improve the charge-discharge performance and cycle performance of sodium-ion batteries, various coating methods have been disclosed in existing technologies. For example, CN 117594769 A discloses a method for preparing layered oxide cathode materials, the materials themselves, and their applications. Specifically, the method for preparing layered oxide cathode materials involves mixing a nickel source, an iron source, a manganese source, an additive metal source, and a sodium source, followed by a first calcination to obtain a calcined intermediate product. This intermediate product is then mixed with a coating agent, followed by a second calcination to obtain the layered oxide cathode material. This method employs a two-stage calcination process to coat multiple metal oxides, resulting in cathode materials that improve charge-discharge capacity, rate performance, and cycle performance to some extent. However, there is still room for further improvement in the final battery performance.

[0028] This invention reveals that the main reason for the difficulty in achieving breakthroughs in battery performance lies in the inherently poor conductivity of metal oxides, coupled with insufficient mechanical strength and corrosion resistance of the coating. Furthermore, this invention addresses this issue by sintering an alloy oxide coating layer onto the surface of a sodium ion-layered oxide. Compared to common metal oxide coatings, the alloy oxide can improve conductivity by varying its metal composition to control the gap between the energy band and conduction band. This significantly enhances conductivity compared to traditional oxides, improving cycle retention while simultaneously enhancing ion diffusion and capacity utilization, thus eliminating the negative impacts of traditional oxide coatings on capacity performance. Additionally, it exhibits superior mechanical properties and structural stability in crystallography.

[0029] Based on this, the present invention has the following technical solution:

[0030] In a first aspect, the present invention provides a method for preparing a sodium-ion cathode material, comprising the following steps:

[0031] S1: Mix a nickel source, an iron source, a manganese source, other metal sources, and a sodium source, and then perform a first calcination treatment to obtain an intermediate product; S2: Mix the intermediate product with a coating agent, and then perform a second calcination treatment to obtain the sodium ion cathode material; the coating agent includes a first coating agent and / or a second coating agent; the first coating agent includes a nickel source; the second coating agent includes a zinc source.

[0032] In this invention, before preparation, the particle size of the raw material metal source is controlled to be in the nanometer range; further, the particle size of the intermediate product is controlled to be 3 to 10 micrometers; and / or, the particle size of the sodium ion cathode material is controlled to be 3 to 10 micrometers.

[0033] In this invention, step S1, after obtaining the intermediate product, further includes a step of naturally cooling the product.

[0034] Preferably, the coating agent includes the first coating agent and the second coating agent.

[0035] More preferably, the coating agent is selected from the first coating agent and the second coating agent.

[0036] According to a preferred embodiment of the present invention, the molar amount a of the first coating agent and the molar amount b of the second coating agent conform to the following relationship: 0.7≤a≤0.9, 0.1≤b≤0.3, a+b=1.

[0037] This invention discovers that by controlling the molar amounts of the first and second coating agents within the aforementioned range, it is possible to further construct a highly conductive alloy oxide coating layer on the surface of layered oxides. This reduces interfacial side reactions, optimizes the overall conductivity of the positive electrode, eliminates the capacity loss inherent in traditional oxide coating layers, and improves charge-discharge performance. Furthermore, compared to traditional metal oxide coating layers, the constructed highly conductive alloy oxide coating layer exhibits higher mechanical strength, significantly reduces volume changes caused by phase transitions, and improves cycle performance.

[0038] According to a preferred embodiment of the present invention, the first coating agent comprises nickel oxide and / or nickel hydroxide; the second coating agent comprises zinc oxide and / or zinc hydroxide.

[0039] According to a preferred embodiment of the present invention, the amount of the coating agent is 0.2 to 2 wt% based on the mass of the intermediate product; preferably, the amount of the coating agent is 0.3 to 0.7 wt%; for example, values ​​such as 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, and 0.7 wt%.

[0040] According to a preferred embodiment of the present invention, during the first calcination treatment, the calcination temperature is controlled to be 800-1200 degrees Celsius.

[0041] More preferably, during the first calcination treatment, the temperature is maintained for 5 to 15 hours after reaching the calcination temperature described above.

[0042] According to a preferred embodiment of the present invention, during the second calcination treatment, the calcination temperature is controlled to be 700–850 degrees Celsius; for example, the calcination temperature is 700 degrees Celsius, 710 degrees Celsius, 720 degrees Celsius, 730 degrees Celsius, 740 degrees Celsius, 750 degrees Celsius, 760 degrees Celsius, 770 degrees Celsius, 780 degrees Celsius, 790 degrees Celsius, 800 degrees Celsius, 810 degrees Celsius, 820 degrees Celsius, 830 degrees Celsius, 840 degrees Celsius, or 850 degrees Celsius, etc.

[0043] In this invention, by controlling the calcination temperature during the second calcination process to the range described above, the purity of the alloy oxide coating layer can be effectively guaranteed, thus avoiding phase separation.

[0044] More preferably, during the second calcination treatment, the temperature is maintained for 2 to 10 hours after reaching the calcination temperature described above.

[0045] More preferably, the heating rates of the first calcination treatment and the second calcination treatment are controlled to be the same or different, ranging from 2 to 10 degrees Celsius per minute.

[0046] More preferably, controlling the calcination temperature of the first calcination treatment to be higher than that of the second calcination treatment can better ensure the crystallinity of the calcination intermediate product, thereby ensuring the stability of the bulk structure.

[0047] According to a preferred embodiment of the present invention, the other metal source includes one or more of aluminum, titanium, calcium, zirconium and zinc.

[0048] More preferably, the other metal source includes a titanium source and / or a calcium source.

[0049] More preferably, the other metal source includes a titanium source and a calcium source.

[0050] Furthermore, the aluminum source includes aluminum oxide; the titanium source includes titanium oxide; the calcium source includes calcium oxide; the zirconium source includes zirconium oxide; and the zinc source includes zinc oxide.

[0051] According to a preferred embodiment of the present invention, the amount of other metal sources is 0.1 to 10 wt%, based on the total mass of the nickel source, iron source and manganese source.

[0052] According to a preferred embodiment of the present invention, the ratio of the total molar amount of nickel in the nickel source, iron in the iron source, manganese in the manganese source, and other metal elements in the metal source to the molar amount of sodium in the sodium source is 1:(0.6 to 1.1).

[0053] According to a preferred embodiment of the present invention, the nickel source includes one or more of nickel oxide, nickel hydroxide, and nickel acetate; the iron source includes ferric oxide and / or ferric oxide; the manganese source includes one or more of manganese dioxide, manganese tetroxide, and manganese acetate; and the sodium source includes one or more of anhydrous sodium carbonate, sodium hydroxide, sodium acetate, and sodium sulfate.

[0054] More preferably, the nickel source includes nickel oxide; the iron source includes ferric oxide; the manganese source includes manganese dioxide; and the sodium source includes sodium carbonate.

[0055] More preferably, the molar ratio of the nickel source, the iron source, and the manganese source is (0.2-0.5):(0.2-0.5):(0.2-0.5).

[0056] Secondly, the present invention provides a sodium ion cathode material, which is prepared by the above-mentioned method for preparing sodium ion cathode materials.

[0057] Thirdly, the present invention provides a sodium-ion battery comprising the aforementioned sodium-ion positive electrode material.

[0058] Example 1

[0059] This embodiment provides a sodium-ion cathode material, the preparation method of which includes the following steps:

[0060] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese dioxide, titanium oxide and calcium oxide were weighed in the stoichiometric ratio Na:Mn:Ni:Fe:Ti:Ca=0.96:0.33:0.28:0.34:0.03:0.02 and added to a high-speed mixer for mixing at 1000 rpm for 10 minutes. The uniformly mixed material was then sintered in an oxygen atmosphere at a rate of 3°C / min to 950°C for 12 hours. The sintered material was then crushed by an air jet mill with the following parameters: air pressure 0.25 MPa, induced draft fan frequency 50 Hz, and classifier wheel frequency 75 Hz. The crushed material was then sieved to obtain a semi-finished product.

[0061] (2) The coating agent NiO and ZnO are mixed in a ball mill at a speed of 1000 rpm for 12 minutes with the mixture obtained in step 1 at a molar ratio of 8:2 (the total mass of the two is 0.3 wt% of the mass of the semi-finished product obtained in step 1). Then the mixture is heated to 800 degrees Celsius in air at a rate of 5 degrees Celsius / minute for sintering. The holding time for sintering is 8 hours. After sieving, the sodium-ion battery cathode material is obtained.

[0062] SEM images of the sodium-ion cathode material prepared above are shown below. Figure 1 XRD images of the sodium ion cathode material can be found in [link to image]. Figure 2 .

[0063] Example 2

[0064] This embodiment provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: the total mass of the coating agent is 1 wt% of the mass of the semi-finished product obtained in step 1.

[0065] Example 3

[0066] This embodiment provides a sodium ion cathode material, the only difference between which preparation method is different from that of Example 1 is that the total mass of the coating agent is 0.1 wt% of the mass of the semi-finished product obtained in step 1.

[0067] Example 4

[0068] This embodiment provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: NiO in step (2) is replaced with an equal amount of Ni(OH)2.

[0069] Example 5

[0070] This embodiment provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: the ZnO in step (2) is replaced with an equal amount of Zn(OH)2.

[0071] Example 6

[0072] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Embodiment 1 is that NiO in step (2) is replaced with an equal amount of Ni(OH)2, and ZnO is replaced with an equal amount of Zn(OH)2.

[0073] Example 7

[0074] This embodiment provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: the ZnO in step (2) is replaced with an equal amount of NiO.

[0075] Example 8

[0076] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Example 1 is that NiO in step (2) is replaced with an equal amount of ZnO.

[0077] Example 9

[0078] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Example 1 is that in step (2), the molar ratio of coating agent NiO and ZnO is 6:4.

[0079] Example 10

[0080] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Example 1 is that in step (2), the molar ratio of coating agent NiO and ZnO is 5:5.

[0081] Example 11

[0082] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Example 1 is that in step (2), the sintering temperature is 900 degrees Celsius.

[0083] Example 12

[0084] This embodiment provides a sodium ion cathode material, the only difference between its preparation method and that of Example 1 is that in step (2), the sintering temperature is 850 degrees Celsius.

[0085] Comparative Example 1

[0086] This comparative example provides a sodium ion cathode material, the preparation method of which differs from that of Example 1 only in that step (2) is not included.

[0087] Comparative Example 2

[0088] This comparative example provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: the coating agent is replaced with equal amounts of boron oxide and silicon oxide in a mass ratio of 8:2.

[0089] Comparative Example 3

[0090] This comparative example provides a sodium ion cathode material, the only difference between which is the preparation method and that of Example 1: the coating agent is replaced with equal amounts of barium oxide and tin oxide in a mass ratio of 8:2.

[0091] Test case

[0092] The sodium-ion cathode materials prepared in the above embodiments and comparative examples were used to fabricate coin-type half-cells for electrical performance testing. The steps are as follows:

[0093] The positive electrode material, conductive carbon (super P), and P-volt DF obtained in the examples and comparative examples were mixed in NMP at a mass ratio of 96:2:2 and dissolved. After thorough stirring, the positive electrode sheet was coated onto aluminum foil using an automatic coating machine. The coated electrode sheet was dried in a vacuum at 105 degrees Celsius for 12 hours, and then rolled using a roller press. The rolled positive electrode sheet was cut into 12 mm diameter discs. Using metallic sodium as the negative electrode sheet and a glass fiber membrane as the separator, and 1 mmol of NaPF6 dissolved in an EC:DEC = 1:1 organic electrolyte, CR2032 coin cells were assembled in an argon-protected glove box. The charge / discharge current of the battery was 240 mA / g. Electrochemical performance tests were then conducted on the batteries obtained in each group at 25 degrees Celsius: voltage 2.0 V-4.0 V, current 0.1 coulomb, and the first charge / discharge specific capacity was measured to obtain the first efficiency.

[0094] The test results are shown in Table 1 below:

[0095] Table 1

[0096]

[0097] The test results of Comparative Example 1 and Comparative Example 1 show that a highly conductive alloy oxide coating layer is formed on the surface of sodium ion layered oxide, which not only improves the cycle retention rate but also enhances ion diffusion and improves capacity utilization.

[0098] By comparing the test results of Example 1 and Example 7, it can be seen that when a single nickel oxide coating layer is formed on the material surface, although it can reduce interfacial side reactions to a certain extent, the conductivity itself is poor and the capacity improvement is small.

[0099] Comparing the test results of Example 1 and Example 8, it can be seen that when a single zinc oxide coating layer is formed on the material surface, although the interfacial side reactions can be reduced to a certain extent, thereby improving the cycle retention rate and first-cycle efficiency, the ion diffusion on the material surface will be greatly affected, resulting in a serious reduction in discharge capacity.

[0100] By comparing the test results of Examples 1 and 9 and 10, it can be seen that when the nickel-zinc ratio of the alloy coating layer formed on the material surface is low, the conductivity of the alloy coating is still low, resulting in a low increase in discharge capacity.

[0101] Comparing the test results of Example 1 and Example 11, it can be seen that excessive coating temperature will lead to excessive consumption of sodium ions on the surface of the core, thereby reducing the number of sodium ions that can be inserted and extracted in the bulk phase and affecting the capacity.

[0102] By comparing the test results of Example 1 and Example 12, it can be seen that when the temperature of the second calcination is lower than that of the first calcination, other unknown structural changes in the bulk phase at higher temperatures can be avoided, ensuring a better coating effect and avoiding excessive loss of bulk active sodium through volatilization.

[0103] By comparing the test results of Example 1 and Comparative Examples 2-3, it can be seen that when other oxides are used for coating, due to the structural differences of different oxides, the physical properties of the alloy oxides formed under the same conditions are different, or they are prone to phase separation to form other impurities, resulting in poor coating effect.

[0104] 2. Cyclic capacity retention test

[0105] The present invention tested the cycle capacity retention of batteries assembled in Example 1 and Comparative Example 1, respectively. The test conditions were: 25 degrees Celsius, voltage of 2.0V-4.0V, charging current of 0.5C, and discharging current of 1C. The results are as follows. Figure 3 As shown. The results indicate that the cycling performance of Example 1 is better than that of Comparative Example 1, demonstrating that the alloy oxide coating layer blocks the electrolyte from corroding the bulk phase and improves cycling stability.

[0106] 3. Ratio performance testing

[0107] The present invention tested the rate performance of batteries assembled in Example 1 and Comparative Example 1, respectively. The test conditions were: 25 degrees Celsius, voltage 2.0V-4.0V, charging current of 0.2 coulombs and discharging current of 0.2 coulombs in the first cycle, charging current of 0.5 coulombs and discharging current of 0.5 coulombs in the second cycle, charging current of 0.5 coulombs and discharging current of 1 coulomb in the third cycle, charging current of 0.5 coulombs and discharging current of 2 coulombs in the fourth cycle, and charging current of 0.5 coulombs and discharging current of 5 coulombs in the fifth cycle. The results are as follows. Figure 4 As shown. The results indicate that Ni 0.8 Zn 0.2 The presence of the O alloy oxide coating improves the ion migration efficiency at the interface, thereby enhancing rate performance.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a sodium-ion cathode material, characterized in that, include: S1: Mix nickel source, iron source, manganese source, other metal source and sodium source, and then perform a first calcination treatment to obtain intermediate product; During the first calcination treatment, the calcination temperature is controlled at 800~1200 degrees Celsius; S2: The intermediate product and the coating agent are mixed, and then subjected to a second calcination treatment to obtain the sodium ion cathode material; during the second calcination treatment, the calcination temperature is controlled at 700~850 degrees Celsius. The coating agent is a mixture of a first coating agent and a second coating agent; the first coating agent is a nickel source; the second coating agent is a zinc source; the nickel source is nickel oxide and / or nickel hydroxide; the zinc source is zinc oxide and / or zinc hydroxide; wherein the molar amount 'a' of the first coating agent and the molar amount 'b' of the second coating agent conform to the following relationship: 0.7 ≤ a ≤ 0.9, 0.1 ≤ b ≤ 0.3, a + b = 1; based on the mass of the intermediate product, the amount of the coating agent used is 0.3 wt% to 0.7 wt%.

2. The method for preparing the sodium-ion cathode material according to claim 1, characterized in that, The other metal sources include one or more of aluminum, titanium, calcium, zirconium, and zinc.

3. The method for preparing the sodium-ion cathode material according to claim 2, characterized in that, The aluminum source includes aluminum oxide; the titanium source includes titanium oxide; the calcium source includes calcium oxide; the zirconium source includes zirconium oxide; and the zinc source includes zinc oxide. Based on the total mass of the nickel, iron, and manganese sources, the amount of other metal sources is 0.1 to 10 wt%.

4. The method for preparing the sodium-ion cathode material according to any one of claims 1 to 3, characterized in that, The ratio of the total molar amount of nickel in the nickel source, iron in the iron source, manganese in the manganese source, and other metal elements in the metal source to the molar amount of sodium in the sodium source is 1:(0.6~1.1).

5. The method for preparing the sodium-ion cathode material according to any one of claims 1 to 3, characterized in that, The nickel source includes one or more of nickel oxide, nickel hydroxide, and nickel acetate; the iron source includes ferric oxide and / or ferric oxide; the manganese source includes one or more of manganese dioxide, manganese tetroxide, and manganese acetate; and the sodium source includes one or more of anhydrous sodium carbonate, sodium hydroxide, sodium acetate, and sodium sulfate.

6. The method for preparing the sodium-ion cathode material according to claim 5, characterized in that, The molar ratio of the nickel source, the iron source, and the manganese source is (0.2~0.5):(0.2~0.5):(0.2~0.5).

7. A sodium-ion cathode material, characterized in that, It is prepared by the method for preparing sodium ion cathode material according to any one of claims 1 to 6.

8. A sodium-ion battery, characterized in that, Includes the sodium ion cathode material as described in claim 7.

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