Sodium-ion layered transition metal oxide cathode material with cerium oxide coating and its preparation method

Abstract

This invention discloses a sodium-ion battery layered transition metal oxide cathode material with cerium oxide coated on its surface. The bulk phase of this cathode material is a layered transition metal oxide Na. x The bulk phase is composed of MO2, and the surface of the bulk phase has a uniform coating layer composed of CeO2. Neither the bulk phase nor the coating layer has any transition metal shifts or vacancies. The layered transition metal oxide Na... x MO2 is an open-phase (OP) miscible phase, where M is a transition metal ion Ni. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of the following; x is the molar ratio, ranging from 0.75 to 0.85. This invention also discloses a method for preparing and applying sodium-electric layered transition metal oxide cathode materials with cerium oxide surface coating. The cathode material of this invention can effectively suppress problems such as transition metal migration, dissolution, and surface amorphization on the surface of layered transition metal oxide materials, resulting in low-cost, high-efficiency, and long-cycle-life materials.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery cathode material technology, and more specifically to a sodium-ion battery layered transition metal oxide cathode material with cerium oxide coated on its surface and its preparation method. Background Technology

[0002] Layered transition metal oxide Na x MO2 (where M is a transition metal element) is considered one of the most promising cathode materials for sodium-ion batteries due to the advantages of sodium resources, such as low price, wide availability, and high theoretical specific capacity, and has attracted widespread attention.

[0003] Layered transition metal oxide Na x MO2 mainly includes O3 and P2 type layered transition metal oxides, but currently reported O3 and P2 type layered oxides Na x MO2 exhibits shortcomings in electrochemical performance. For instance, O3-NaMnO2 cathode materials can provide a discharge capacity as high as 197 mAh / g (J. Electrochem. Soc., 2011, 158, A1307), but during charge and discharge, the lattice structure is prone to distortion due to oxygen layer slippage, leading to rapid capacity decay. Compared to O3-NaMnO2, P2-Na... 0.67 MnO2 cathode material has good rate performance, but when charged to a high potential, the P2 phase will also experience oxygen layer sliding, resulting in a phase transition from P2 to O2, and thus a drastic change in unit cell volume. This is very unfavorable as an electrode material for commercial sodium-ion batteries (Angew. Chem. Int. Ed., 2016, 128, 12952).

[0004] Compared to pure O and pure P phases, OP mixed-phase layered transition metal oxides possess both the high initial efficiency of the pure O phase and the relatively stable structure of the pure P phase. However, as a manganese-based material, OP still exhibits the inherent intrinsic defects of manganese-based materials, and its electrochemical performance has significant room for improvement. Therefore, modifying layered transition metal oxide cathode materials for sodium-ion batteries to enhance their electrochemical stability is crucial.

[0005] Surface coating is a common method for material modification, but currently reported surface-coated modified materials still have certain shortcomings in electrochemical performance. For example, the P3 phase material Na+ coated with phosphate... 0.65 Mn 0.75 Ni 0.25O2 (Yu Wang, 2019, 372, 1066) can improve the cycling performance of the material from 76.4% to 92.4% at 0.2C, but only increases the capacity from 130.2 mAh / g to 133.6 mAh / g. The P2 phase material N with Al2O3 surface coating... a0.5 Mn 0.5 Co 0.5 O2 (HariVignesh Ramasamy, 2019, 564, 467) can increase its capacity from 154 mAh / g to 174 mAh / g at 0.5C, but only from 75% to 78% in terms of cycling performance. Summary of the Invention

[0006] The purpose of this invention is to address the poor electrochemical performance of existing sodium-ion battery layered transition metal oxide cathode materials by providing a sodium-ion battery layered transition metal oxide cathode material with cerium oxide coating and its preparation method. Under specific phase composition conditions, a one-step sintering surface coating technology is used to obtain a cathode material with an OP mixed phase in the bulk and a uniform CeO2 coating on the surface. This effectively suppresses problems such as transition metal migration, dissolution, and surface amorphization on the surface of layered transition metal oxide materials. The cathode material is low-cost to prepare, has high initial efficiency, and long cycle life.

[0007] The first aspect of this invention relates to a sodium-electric layered transition metal oxide cathode material with a surface coated with cerium oxide, wherein the bulk phase of the cathode material is a layered transition metal oxide Na. x The bulk phase is composed of MO2, and the surface of the bulk phase has a uniform coating layer composed of CeO2. There are no transition metal shifts or vacancies in the bulk phase and the coating layer.

[0008] The layered transition metal oxide Na x MO2 is an open-phase (OP) miscible phase, where M is a transition metal ion Ni. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of the following; x is the molar ratio, ranging from 0.75 to 0.85.

[0009] In an optional embodiment, the thickness of the coating layer is 1–20 nm.

[0010] The second aspect of this invention relates to a method for preparing the aforementioned sodium-electric layered transition metal oxide cathode material with cerium oxide coating, comprising the following steps:

[0011] Using transition metal source, sodium source and cerium source as raw materials, they are ball-milled and mixed evenly according to stoichiometric ratio, and then heat-treated and cooled in air atmosphere to obtain sodium-electric layered transition metal oxide cathode material with cerium oxide coating on the surface.

[0012] In an optional embodiment, the transition metal source corresponds to Ni as the transition metal ion. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of them.

[0013] In an optional embodiment, the transition metal source is a transition metal salt, transition metal oxide, or transition metal hydroxide; the transition metal salt is a carbonate, acetate, nitrate, chloride, sulfate, borate, or phosphate of the transition metal.

[0014] In an optional embodiment, the sodium source is one or more of sodium carbonate, sodium nitrate, sodium sulfate, sodium phosphate, sodium fluoride, sodium iodide, sodium oxalate, and sodium hydroxide.

[0015] In an optional embodiment, the cerium source is one or more of cerium carbonate, cerium nitrate, cerium sulfate, cerium phosphate, cerium hydroxide, cerium chloride, cerium oxide, and cerium trioxide.

[0016] In an optional embodiment, the masses of the transition metal source and the sodium source are determined according to the layered transition metal oxide Na. x The MO2 was prepared according to the stoichiometric ratio, with the mass of the cerium source being 0.1% to 10% of the total mass of the transition metal source and the sodium source.

[0017] In an optional embodiment, the heat treatment conditions are: heat treatment at 900±10℃ for 15 to 18 hours.

[0018] The third aspect of the present invention relates to the application of the aforementioned sodium-ion battery with a cerium oxide-coated sodium-ion layered transition metal oxide cathode material in sodium-ion batteries.

[0019] Compared with the prior art, the significant advantages of the present invention are as follows:

[0020] The sodium-ion battery layered transition metal oxide cathode material with cerium oxide coating of the present invention synthesizes an OP mixed-phase layered transition metal oxide by controlling the Na / Mn ratio and sintering temperature. A CeO2 layer is simultaneously coated on the surface of the OP mixed-phase layered transition metal oxide by a one-step sintering method. The surface CeO2 coating inhibits the formation of surface Na2CO3, allowing more Na to enter the bulk phase of the material, resulting in a higher Na content and an OP phase in the bulk phase. This leads to a higher first-efficiency cathode material while ensuring structural stability.

[0021] In addition, the intrinsic characteristics of the CeO2 coating layer improve the electronic conductivity of the material, and the CeO2 coating layer can also suppress the dissolution of transition metals, which greatly improves the structural stability of the material and makes the material have better cycling performance.

[0022] This invention utilizes CeO2 and OP mixed-phase layered metal oxides (Na) x By leveraging the phase separation characteristics during MO2 synthesis, an OP mixed-phase layered transition metal oxide cathode material coated with CeO2 was synthesized via a one-step sintering method. The coating layer is uniform and robust, resulting in excellent electrical properties. Attached Figure Description

[0023] Figure 1 These are the XRD spectra of samples prepared in Examples 1, 2, 3, 4, and 5 of the present invention, as well as Comparative Example 1.

[0024] Figure 2 These are the XRD spectra of the samples prepared in Example 3 and Comparative Example 2 of the present invention.

[0025] Figure 3 These are SEM images of samples obtained from the embodiments and comparative examples of the present invention; wherein, a is the sample of Example 1, b is the sample of Example 2, c is the sample of Example 3, d is the sample of Example 4, e is the sample of Example 5, f is the sample of Comparative Example 1, and g is the sample of Comparative Example 2.

[0026] Figure 4 These are TEM images of samples obtained from embodiments and comparative examples of the present invention; wherein, a is the sample of Example 3 and b is the sample of Comparative Example 1.

[0027] Figure 5 For Comparative Example 1, the first charge-discharge curves of the samples prepared in Examples 1, 2, 3, 4, and 5 at a current density of 0.1 A / g are shown.

[0028] Figure 6 The first charge-discharge curves of the samples prepared for Comparative Example 2 and Example 3 at a current density of 0.1 A / g are shown.

[0029] Figure 7 For Comparative Example 1, the long cycle diagrams of samples prepared in Examples 1, 2, 3, 4, and 5 at a current density of 1 A / g for 2000 cycles are shown.

[0030] Figure 8 Long cycle diagrams of 2000 cycles at a current density of 1 A / g for samples prepared for Comparative Example 2 and Example 3. Detailed Implementation

[0031] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0032] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described below in more detail, can be implemented in any of a number of ways.

[0033] This invention designs a novel cathode material for sodium-ion batteries. By coating a CeO2 layer onto the surface of a sodium-ion layered transition metal oxide with an op-phase mixture, problems such as transition metal migration, dissolution, and surface amorphization on the surface of the layered transition metal oxide material are effectively suppressed, resulting in a low-cost, high-efficiency, and long-cycle-life layered transition metal oxide cathode material for sodium-ion batteries.

[0034] In an exemplary embodiment of the present invention, a sodium-ion battery layered transition metal oxide cathode material with a surface coated with cerium oxide is provided, wherein the bulk phase of the cathode material is a layered transition metal oxide Na. x The bulk phase is composed of MO2, and the surface of the bulk phase has a uniform coating layer composed of CeO2. There are no transition metal shifts or vacancies in the bulk phase and the coating layer.

[0035] The layered transition metal oxide Na x MO2 is an open-phase (OP) miscible phase, where M is a transition metal ion Ni. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of the following; x is the molar ratio, ranging from 0.75 to 0.85.

[0036] It should be understood that when M consists of two or more types of transition metal ions, the molar ratio between different transition metal ions is not limited, as long as the total molar ratio of transition metal ions is 1.

[0037] In an optional embodiment, the thickness of the coating layer is 1–20 nm.

[0038] By coating materials with specific surfaces, new physical, chemical, and other functionalities can be acquired, significantly improving the material's dispersibility and compatibility with other substances. Common coating methods include mechanical mixing, solid-state reaction, hydrothermal methods, sol-gel methods, precipitation methods, and deposition methods. Among these, solid-state synthesis is the simplest, most convenient, and most suitable for commercialization.

[0039] However, current solid-state surface coating methods are often combined with sol-gel or precipitation methods, or involve secondary sintering. The entire process is still relatively complicated and prone to problems such as uneven or weak coating.

[0040] Therefore, in another exemplary embodiment of the present invention, a method for preparing the aforementioned sodium-electric layered transition metal oxide cathode material with cerium oxide coating is provided, comprising the following steps:

[0041] Using transition metal source, sodium source and cerium source as raw materials, they are ball-milled and mixed evenly according to stoichiometric ratio, and then heat-treated and cooled in air atmosphere to obtain sodium-electric layered transition metal oxide cathode material with cerium oxide coating on the surface.

[0042] In an optional embodiment, the transition metal source corresponds to Ni as the transition metal ion. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of them.

[0043] In an optional embodiment, the transition metal source is a transition metal salt, transition metal oxide, or transition metal hydroxide; the transition metal salt is a carbonate, acetate, nitrate, chloride, sulfate, borate, or phosphate of the transition metal.

[0044] In an optional embodiment, the sodium source is one or more of sodium carbonate, sodium nitrate, sodium sulfate, sodium phosphate, sodium fluoride, sodium iodide, sodium oxalate, and sodium hydroxide.

[0045] In an optional embodiment, the cerium source is one or more of cerium carbonate, cerium nitrate, cerium sulfate, cerium phosphate, cerium hydroxide, cerium chloride, cerium oxide, and cerium trioxide.

[0046] In an optional embodiment, the masses of the transition metal source and the sodium source are determined according to the layered transition metal oxide Na. x The MO2 was prepared according to the stoichiometric ratio, with the mass of the cerium source being 0.1% to 10% of the total mass of the transition metal source and the sodium source.

[0047] In an optional embodiment, the heat treatment conditions are: heat treatment at 900±10℃ for 15 to 18 hours.

[0048] In other exemplary embodiments of the present invention, the application of the aforementioned sodium-ion battery with cerium oxide coating is also provided. When the sodium-ion battery with cerium oxide coating is applied, the battery exhibits excellent rate performance and cycle stability.

[0049] To facilitate better understanding, the present invention will be further illustrated below with several specific examples, but the processing technology is not limited thereto, and the content of the present invention is not limited thereto.

[0050] In the following examples and comparative examples, the amount of cerium source added is calculated as a percentage of the mass of cerium source relative to the total mass of Mn2O3, NiO, Fe2O3, and Na2CO3.

[0051] Example 1

[0052] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed uniformly in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with 2% excess Na source), and 0.1 wt% cerium nitrate were ball-milled (400 r / min, 6 h). The mixture was then heated at 900 °C for 15 h and cooled to obtain a layered transition metal oxide powder with a surface coating.

[0053] Example 2

[0054] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with 2% excess Na source), and 1 wt% cerium nitrate were ball-milled (400 r / min, 6 h). After being mixed evenly, the mixture was heated at 900 °C for 15 h and then cooled to obtain a layered transition metal oxide powder with a surface coating.

[0055] Example 3

[0056] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed uniformly in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with 2% excess Na source) and 2wt% cerium nitrate were ball-milled (400 r / min, 6 h), and then heated at 900 °C for 15 h and cooled to obtain a layered transition metal oxide powder with a surface coating.

[0057] Example 4

[0058] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed uniformly in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with Na source in excess of 2%), and 5wt% cerium nitrate were ball-milled (400 r / min, 6 h). The mixture was then heated at 900 °C for 15 h and cooled to obtain a layered transition metal oxide powder with a surface coating.

[0059] Example 5

[0060] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed uniformly by ball milling (400 r / min, 6 h) with 10 wt% cerium nitrate, and then heated at 900 °C for 15 h and cooled to obtain a layered transition metal oxide powder with a surface coating.

[0061] Example 6

[0062] Set 0.8 mol Na 0.85 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were mixed uniformly by ball milling (400 r / min, 6 h) with 2 wt% cerium nitrate, and then heated at 900 °C for 15 h and cooled to obtain a layered transition metal oxide powder with a surface coating.

[0063] Comparative Example 1

[0064] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were ball-milled (400 r / min, 6 h) in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with Na source in excess of 2%) until homogeneous. The mixture was then heated at 900℃ for 15 h and cooled to obtain Na. 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2 is used as the positive electrode material.

[0065] Comparative Example 2

[0066] Set 0.8 mol Na 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2, Mn2O3, NiO, Fe2O3, and Na2CO3 were ball-milled (400 r / min, 6 h) in a molar ratio of Na:Ni:Fe:Mn = 0.75:0.2:0.3:0.5 (with Na source in excess of 2%) until homogeneous. The mixture was then heated at 900℃ for 15 h and cooled to obtain Na. 0.75 Ni 0.2 Fe 0.3 Mn 0.5 O2 is used as the positive electrode material.

[0067] The Na obtained above 0.75 Ni 0.2 Fe 0.3 Mn 0.5 Adding 2wt% cerium source to O2 and heating at 900℃ for 15h, followed by cooling, yields a layered transition metal oxide powder with a surface coating.

[0068] XRD

[0069] XRD tests were performed on the materials obtained in Examples 1-5 and Comparative Examples 1-2, and the results are as follows: Figure 1 and Figure 2 As shown.

[0070] As can be seen from the figure, the samples of Examples 1-5 have characteristic peaks of O phase, P phase and CeO2, which proves that the bulk phase of the cathode material obtained by the method of the present invention is mainly composed of O phase, P phase and CeO2. Moreover, as the mass of Ce source increases, the peak of CeO2 phase becomes stronger and stronger, indicating that CeO2 accounts for more and more of the material.

[0071] The sample of Comparative Example 1 consists of O phase and P phase. The sample of Comparative Example 2, obtained after two-step sintering, also consists of O phase, P phase and CeO2, but has more impurity peaks, indicating that the coating is not uniform. Furthermore, based on the comparison between Comparative Example 1 and Examples 1-5, it can be proven that the CeO2 layer is coated on the surface of the bulk phase.

[0072] SEM, TEM

[0073] The materials obtained in Examples 1-5 and Comparative Examples 1-2 were subjected to SEM and TEM tests, and the results are as follows: Figure 3 and Figure 4 As shown.

[0074] As can be seen from the SEM images, the samples in the comparative example and the embodiment all have irregular plate-like morphology. Combined with TEM, it can be seen that the sample modified with cerium source has a coating layer on the surface of the bulk phase. As the mass of cerium source increases, the coating layer on the material surface becomes more and more obvious. The thickness of the CeO2 coating layer on the surface of Example 3 is about 3 nm. The thickness of the coating layer needs to be controlled within 1 to 20 nm to ensure the final electrochemical performance.

[0075] As can be seen from the above, the present invention successfully synthesized sodium-electric layered transition metal oxides with CeO2 coating on the surface, and the sodium-electric layered transition metal oxides are OP mixed phases.

[0076] Electrode preparation and electrochemical performance testing

[0077] The prepared cathode material was uniformly mixed with superconducting carbon black (Super P) and polyvinylidene fluoride (PVDF) at a mass ratio of 8:1:1 and then dissolved in N-methylpyrrolidone (NMP). The mixture was then coated onto the surface of aluminum foil and dried in a vacuum oven at 80°C for 10 hours to obtain a surface-coated layered transition metal oxide electrode.

[0078] A half-cell was assembled in an argon-atmosphere glove box using a surface-coated layered transition metal oxide electrode as the positive electrode, a sodium metal sheet as the negative electrode, and 1.0 mol / L NaPF6 / propylene carbonate as the electrolyte. The electrochemical performance of the surface-coated layered transition metal oxide electrode material, including specific capacity, rate performance, cycle stability, and initial coulombic efficiency, was tested in the range of 2–4 V.

[0079] The test results are shown in Table 1 and Figure 5-8 As shown.

[0080] Table 1

[0081]

[0082] Combination Figure 5-8 As shown in Table 1, the addition of the CeO2 coating significantly improves the initial efficiency of the material. When 2% wt cerium nitrate is added, the initial efficiency reaches as high as 98% (e.g., Figure 5 (As shown). Furthermore, the sample sintered using the one-step method of this invention exhibits higher first-pass efficiency (98%) and higher specific capacity (103.5 mAh / g) (as shown). Figure 6 (As shown).

[0083] The addition of the CeO2 coating significantly improved the material's cycling performance; when 2% wt cerium nitrate was added, the cycling performance improved by 19% (e.g., Figure 7 (As shown). Furthermore, the one-step sintering of this invention results in a higher cycle retention rate (84.2%) and a higher specific capacity (77.7 mAh / g) (as shown). Figure 8 (As shown).

[0084] As can be seen from the test results of Comparative Examples 1-2 and Example 3, the coating of CeO2 on the material surface inhibits the formation of surface Na2CO3, allowing more Na to enter the bulk of the material, resulting in a higher Na content and thus improving the first-stage efficiency of the battery. Under the condition of OP mixing, the cathode material coated with CeO2 layer makes the battery exhibit a higher first-stage efficiency. This shows that the cathode material of the present invention improves the first-stage efficiency under OP mixing and surface CeO2 layer conditions.

[0085] Furthermore, the CeO2 coating can suppress the dissolution of transition metals, greatly improving the structural stability of the material and resulting in better cycling performance. The electrochemical performance is optimal when the cerium source content reaches 2% wt. As the cerium source content continues to increase, the CeO2 coating thickens, increasing the amount of electrons and Na+. + The mass transfer resistance of diffusion deteriorates the electrochemical performance of the material.

[0086] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating, characterized in that, The bulk phase of the cathode material is a layered transition metal oxide Na. x The bulk phase is composed of MO2, and the surface of the bulk phase has a uniform coating layer composed of CeO2. There are no transition metal shifts or vacancies in the bulk phase and the coating layer. The layered transition metal oxide Na x MO2 is an open-phase (OP) miscible phase, where M is a transition metal ion Ni. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3+ Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of the following; x is the molar ratio, ranging from 0.75 to 0.85; Among them, transition metal source, sodium source and cerium source are used as raw materials. After being ball-milled and mixed evenly according to stoichiometric ratio, they are heat-treated in air atmosphere and then cooled to obtain sodium-electric layered transition metal oxide cathode material with cerium oxide coating on the surface. The heat treatment conditions are: heat treatment at 900±10℃ for 15~18h.

2. The sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 1, characterized in that, The thickness of the coating layer is 1–20 nm.

3. A method for preparing a sodium-ion layered transition metal oxide cathode material with a surface coated with cerium oxide as described in any one of claims 1-2, characterized in that, Includes the following steps: Using transition metal source, sodium source and cerium source as raw materials, they are ball-milled and mixed evenly according to stoichiometric ratio, and then heat-treated and cooled in air atmosphere to obtain sodium-electric layered transition metal oxide cathode material with cerium oxide coating on the surface.

4. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, In the transition metal source, the corresponding transition metal ion is Ni. 2+ Ni 3+ Fe 3+ Cu 2+ Co 3+ Cr 3 + Zn 2+ Ti 4+ V 5+ 、Nb 5+ Li + Mn 3+ Mn 4+ One or more of them.

5. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, The transition metal source is a transition metal salt, transition metal oxide, or transition metal hydroxide; the transition metal salt is a transition metal carbonate, acetate, nitrate, chloride, sulfate, borate, or phosphate.

6. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, The sodium source is one or more of sodium carbonate, sodium nitrate, sodium sulfate, sodium phosphate, sodium fluoride, sodium iodide, sodium oxalate, and sodium hydroxide.

7. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, The cerium source is one or more of cerium carbonate, cerium nitrate, cerium sulfate, cerium phosphate, cerium hydroxide, cerium chloride, cerium oxide, and cerium trioxide.

8. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, The quality of the transition metal source and the sodium source is determined according to the layered transition metal oxide Na. x The MO2 was prepared according to the stoichiometric ratio, with the mass of the cerium source being 0.1% to 10% of the total mass of the transition metal source and the sodium source.

9. The method for preparing the sodium-electric layered transition metal oxide cathode material with cerium oxide surface coating according to claim 3, characterized in that, The heat treatment conditions are: heat treatment at 900±10℃ for 15~18h.

10. The application of a sodium-ion battery with a cerium oxide-coated sodium-ion layered transition metal oxide cathode material as described in any one of claims 1-2.

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