A sodium-ion battery layered oxide cathode material based on high ionic potential doping element combination and a preparation method thereof

Abstract

The application discloses a sodium ion battery layered oxide positive electrode material based on a high ion potential doping element combination and a preparation method thereof. m N n O2, wherein m and n range from 0 to 1 and m+n=1, M is an element participating in charge compensation and is at least one of Ni, Fe, Mn and Co; Na is a base element; and N is an element not participating in charge compensation and is at least one of Mg, Ti, V, Cr B, Al, Ga, B and Ga. ‑1 The application selects more than one kind of doping high ion potential element to make the weighted ion potential of the doping element metal higher than a critical value 6 Å, so that the material has better sodium ion diffusion kinetics and rate performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion secondary battery technology, and more specifically, to a layered oxide cathode material for sodium-ion batteries based on a combination of high ion potential doping elements and its preparation method. Background Technology

[0002] As a core component of sodium-ion batteries, the performance and cost of cathode materials directly affect the overall performance and commercial prospects of the battery. Currently, research on cathode materials for sodium-ion batteries mainly focuses on three major systems: polyanionic compounds, Prussian blue analogs, and layered transition metal oxides. Among them, polyanionic compounds and Prussian blue analogs, due to their stable three-dimensional framework and open ion channel structure, usually exhibit good rate performance and cycle stability, but still face problems such as insufficient conductivity, residual water of crystallization, and dissolution of transition metal ions.

[0003] In contrast, layered transition metal oxides (TLMOs) are considered the most promising cathode materials due to their high specific capacity, operating voltage, and energy density, coupled with low raw material costs and simple preparation processes. However, these materials are prone to structural distortion during cycling, leading to capacity decay and decreased cycle stability. Furthermore, the large radius of sodium ions results in slow ion diffusion kinetics. In addition, most layered oxides are hygroscopic and prone to side reactions with air or electrolytes, further affecting their material stability and electrochemical performance. These factors collectively limit the practical application of layered transition metal oxide cathodes.

[0004] To address the problems inherent in layered transition metal oxide cathodes, existing technologies offer several strategies to improve their electrochemical performance, among which ion doping is a widely used approach. Ion doping can be performed with a single element or multiple elements. By partially replacing sodium, transition metals, or oxygen in the material, it effectively suppresses harmful phase transitions during deep desodium removal, alleviates volume expansion, improves conductivity, lowers migration barriers, and ultimately extends cycle life and enhances rate performance. Multi-element doping is even more widely used because it allows for systematic control of doping sites to achieve corresponding performance improvements. Furthermore, doping can modulate the electron distribution around lattice oxygen, activating the electrochemical activity of lattice oxygen under high voltage, contributing additional capacity, and increasing energy density. Currently, elements such as lithium, magnesium, aluminum, copper, zinc, and titanium have been widely used in doping research, all demonstrating positive improvements in cathode performance.

[0005] For example, modification by doping anion sites and transition metal sites within the P2-type layered oxide cathode of sodium-ion batteries often exhibits a synergistic effect, thereby enhancing the performance of these batteries. Through a Zn / F dual-site doping strategy, P2-Na... 0.67 Ni 0.15 Fe0.20 Mn 0.65 The performance of O2(NFM) was significantly enhanced. P2-Na doped materials were prepared using solid-state and co-precipitation methods. 0.67 Zn 0.05 Ni 0.15 Fe 0.20 Mn 0.60 O 1.95 F 0.05 (ZNFMF) exhibited excellent cycling stability and rate performance in electrochemical tests. Zn / F doping optimized the local electronic structure of the material, lowered the valence state of the transition metal (TM) element, enhanced the binding energy between lattice oxygen and TM, shortened the TM-O bond length, effectively suppressed structural distortion, and improved the material's cycling performance and structural stability. While the cycling performance was significantly improved, the rate performance improvement was not significant, reaching only 70 Ah·g at a current density of 5C. -1 The capacity improvement at high currents compared to the matrix material is not significant. The designed Na... 0.67 Zn 0.05 Ni 0.15 Fe 0.20 Mn 0.60 O 1.95 F 0.05 The doping element is Zn, and the calculated weighted ionic potential is 2.7 Å. -1 .

[0006] By achieving multi-element doped Cu, Fe, and Mn base-like oxides (HE-CFMO) Na 0.95 Li 0.05 Mg 0.05 Cu 0.20 Fe 0.22 Mn 0.35 Ti 0.13 O2. The HE-CFMO cathode possesses a uniformly stress-distributed transition metal (TM) layer, providing appropriate interlayer spacing to maintain structural stability and enhance Na. + Ion diffusion. Furthermore, Li doping in the TM layer increases the Mn valence state, effectively suppressing the John-Teller effect and thus stabilizing the layered structure during cycling. The HE-CFMO cathode exhibits super cycling performance, retaining 95% of its capacity after 300 cycles. Rate performance at 5C is close to 98 mAh g⁻¹. -1 The capacity. The designed Na 0.95 Li 0.05 Mg 0.05 Cu 0.20 Fe 0.22 Mn 0.35 Ti 0.13The O2 is doped with Li, Mg, and Ti, and the calculated weighted ionic potential is 4.63 Å. -1 .

[0007] via P2-Na 0.85 Mn 0.7 Ni 0.3 O2-derived O3-Na 0.85 Mn 0.45 Ni 0.25 Li 0.05 Cu 0.1 Ti0. 15 The O2 (O3-NMNLCTO) cathode incorporates P-type characteristics, particularly a large Na interlayer distance of 3.29 Å. By employing a multi-element doping strategy to integrate P-type features into the O3 framework, O3-NMNLCTO achieves a rapid O3-P3 phase transition in the low-pressure region and induces a P3+P3' solid solution transition. Therefore, the customized O3-NMNLCTO cathode achieves high performance at 10 m·Ag⁻¹. -1 It has 135.6 Ah·g -1 Discharge capacity, excellent cycle stability (at 1 Ag) -1 It retains 91.8% of its capacity after 1500 cycles and has excellent rate performance (approximately 94 Ah·g at 5C). -1 The designed Na 0.85 Mn 0.45 Ni 0.25 Li 0.05 Cu 0.1 Ti 0.15 The O2 dopants are Li, Cu, and Ti, and the calculated weighted ionic potential is 3.96 Å. -1 .

[0008] Layered Na 0.67 Li 0.1 Co 0.1 Cu 0.1 Ni 0.1 Ti 0.1 Mn 0.5 The multi-element doped high-entropy design of the O2 cathode features a self-regulating mechanism, enabling scalable specific capacity and energy density. During the initial charging process, the oxygen redox reaction is activated, accompanied by self-regulation of the active elements, strengthening ionic bonds, and forming vacancy walls near TM vacancies, thereby preventing the migration of transition metal elements. Therefore, the Mn-HEO cathode exhibits a stable structure during cycling. It displays near-zero strain over a wide voltage range of 2.0–4.5 V, exhibiting a significant specific capacity (177 Ah·g at 0.05 C). -1It exhibits excellent long-term cycling stability (87.6% capacity retention after 200 cycles at 2C). Furthermore, the material achieves a capacity of 96.4 Ah·g at 4C rate. -1 The designed Na 0.67 Li 0.1 Co 0.1 Cu 0.1 Ni 0.1 Ti 0.1 Mn 0.5 The non-variable valence elements of O2 are Li, Ti, and Cu, and the calculated weighted ionic potential is 3.08 Å. -1 .

[0009] The introduction of the concept of ionic potential into layered oxides for sodium-ion batteries has sparked considerable discussion. Ionic potential is the ratio of ionic charge to radius. It represents the electrostatic attraction of an ion to surrounding charges. (This is based on the previous discussion of Na...) 0.67 Zn 0.05 Ni 0.15 Fe 0.20 Mn 0.60 O 1.95 F 0.05， Na 0.95 Li 0.05 Mg 0.05 Cu 0.20 Fe 0.22 Mn 0.35 Ti 0.13 O2, Na 0.85 Mn 0.45 Ni 0.25 Li 0.05 Cu 0.1 Ti 0.15 O2, Na 0.67 Li 0.1 Co 0.1 Cu 0.1 Ni 0.1 Ti 0.1 Mn 0.5 The weighted ionic potential of O2-doped metal elements is calculated to be 2.7 Å. -1 4.63 Å -1 3.96 Å -1 3.08 Å -1 Overall, the values ​​are low, and the rate performance has not reached a good level.

[0010] As can be seen, in most of the existing doping methods for layered oxides, the weighted ion potential of the doped metals in the resulting materials does not reach a very high level, with most not exceeding 6 Å. -1This results in poor rate performance. Therefore, developing a layered oxide material that can effectively improve rate performance is one of the important problems that needs to be solved. Summary of the Invention

[0011] To address the aforementioned problems in existing technologies, this invention provides a layered oxide cathode material for sodium-ion batteries based on a combination of high-ionic-potential doping elements. By doping with high-ionic-potential elements, the metal-weighted ionic potential of the doping elements is made higher than the critical value of 6 Å. -1 To improve the rate performance of materials.

[0012] This application also provides a method for preparing layered oxide cathode materials for sodium-ion batteries based on combinations of high ionic potential doping elements.

[0013] To solve the above problems, the present invention adopts the following technical solution: a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doping elements, the general structural formula of which is NaM m N n O2, where m and n are in the range of 0 to 1 and satisfy m+n=1, M is an element that participates in charge compensation and is selected from at least one of Ni, Fe, Mn, and Co; Na is a matrix element; N is an element that does not participate in charge compensation and is selected from at least one of Mg, Ti, V, Cr, B, Al, and Ga.

[0014] Furthermore, element N is a combination of high ionic potential doped elements, whose weighted ionic potential... The calculation formula is as follows:

[0015] ,

[0016] in, The ionic potential is expressed as φ = z / r, where z is the electric charge and r is the ionic radius. Indicates the first The number of moles of element N. The weighted ionic potential represents the total number of moles of N element. The value is greater than 6 Å -1 .

[0017] Furthermore, the average particle size of the cathode material is between 3 μm and 7 μm.

[0018] A method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements, wherein the cathode material is synthesized by solid-state reaction. Specifically, sodium source and metal oxide raw materials are weighed according to stoichiometric ratio, mixed evenly, and then ball-milled for 5-8 hours to obtain precursor powder. The precursor powder is placed in a muffle furnace and calcined at 850℃-950℃ for 10-15 hours in air atmosphere to obtain the layered oxide cathode material for sodium-ion batteries.

[0019] Furthermore, the sodium source is Na2CO3.

[0020] Furthermore, the metal oxide raw material includes oxides of element M and oxides of element N, wherein the oxide of element M includes at least one of NiO, Fe2O3, and MnO2.

[0021] A method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements, wherein the cathode material is synthesized by a co-precipitation reaction. Specifically, metal sulfate powder is dissolved in deionized water to prepare a mixed solution, and the resulting mixed solution is pumped into a reaction vessel. Simultaneously, NaOH solution is added to the reaction vessel as a precipitant and NH4OH solution is added as a pH control agent. During the co-precipitation process, the pH value is maintained between 10 and 11, and the amounts of NaOH solution and NH4OH solution are adjusted based on the pH value.

[0022] During the co-precipitation process, the temperature of the mixed solution is controlled at 40-60℃, the pH value is 10-11, and the stirring speed is 200-400rpm;

[0023] The powder obtained from coprecipitation was filtered, washed, and dried in an oven at 80-120℃ to obtain the precursor powder.

[0024] The dried precursor powder is ground and mixed with sodium source and N element oxide to obtain mixed powder. The muffle furnace is heated to 300-500℃ and held for 5-10h to remove the water of crystallization in the precursor. The temperature is then raised to 850-950℃ and held for 10-15h for high-temperature sintering to obtain the high ionic potential layered oxide cathode material.

[0025] Furthermore, the metal sulfate is selected from at least one of NiSO4, FeSO4, and MnSO4.

[0026] Furthermore, the N element oxide is selected from at least one of TiO2, MgO, and Al2O3.

[0027] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0028] 1. The sodium-ion layered oxide cathode material provided in this application, by introducing one or more high-ion-potential elements (at least one of Mg, Ti, V, Cr, B, Al, Ga) to make the weighted ion potential of the dopant element metal higher than the critical value of 6 Å. -1 This material effectively shields the Coulomb repulsion between the sodium ion layer and the transition metal layer, while expanding the interlayer spacing of the sodium layer, resulting in better sodium ion diffusion kinetics and rate performance. Furthermore, by limiting the critical ion potential threshold, this material simultaneously optimizes sodium ion diffusion kinetics and high-rate structural stability, making it particularly suitable for high-power, long-life sodium-ion batteries.

[0029] 2. The preparation method provided in this application, wherein the solid-state method only requires conventional ball milling and high-temperature solid-state sintering, without other complex processes, and has high compatibility with existing cathode material production lines; the co-precipitation method also does not require a high-pressure or strong oxidation environment, the process conditions are easy to control, the material quality is stable, and the sodium source is widely available, making it easy to achieve large-scale industrial production. Attached Figure Description

[0030] Figure 1 This is an XRD result diagram of the layered oxide cathode material described in Example 1 of this application;

[0031] Figure 2 This is a SEM image of the layered oxide cathode material prepared by solid-state method in Example 1 of this application;

[0032] Figure 3 This is a SEM image of the layered oxide cathode material prepared by the co-precipitation method in Example 2 of this application;

[0033] Figure 4 This is a flowchart of the synthesis steps for preparing layered oxides using a solid-state method in Example 1 of this application;

[0034] Figure 5 This is a flowchart of the synthesis steps for preparing layered oxides using the co-precipitation method in Example 2 of this application;

[0035] Figure 6 This is a charge-discharge curve diagram of the first three cycles at a current density of 0.2C for Embodiment 1 of this application;

[0036] Figure 7 This is a rate performance diagram of the target material in Embodiment 1 of this application, wherein the current density is 0.2C, 0.5C, 1C, 2C, and 5C, respectively, for five cycles. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] This application provides a layered oxide cathode material for sodium-ion batteries based on a combination of high ion potential doped elements, with the general structural formula NaM. m N n O2, where m and n are in the range of 0 to 1 and satisfy m+n=1, M is an element that participates in charge compensation and is selected from at least one of Ni, Fe, Mn, and Co; Na is a matrix element; N is an element that does not participate in charge compensation and is selected from at least one of Mg, Ti, V, Cr, B, Al, and Ga.

[0039] The element N is a combination of high ionic potential doped elements, whose weighted ionic potential The calculation formula is as follows:

[0040] ,

[0041] in, The ionic potential is expressed as φ = z / r, where z is the electric charge and r is the ionic radius. Indicates the first The number of moles of element N. The weighted ionic potential represents the total number of moles of N element. The value is greater than 6 Å -1 .

[0042] The average particle size of the cathode material is between 3μm and 7μm, such as 3μm, 5μm, 6μm, etc.

[0043] In some embodiments, the cathode material described in this application is synthesized by solid-state reaction. Specifically, sodium source and metal oxide raw material are accurately weighed according to stoichiometric ratio, mixed evenly, and then ball-milled for 5-8 hours to obtain precursor powder. The precursor is placed in a muffle furnace and calcined at 850-950°C for 10-15 hours in air atmosphere to obtain the corresponding high ionic potential layered oxide material. The sodium source is Na2CO3. The metal oxide raw material includes oxides of element M and oxides of element N. The oxide of element M includes at least one of NiO, Fe2O3, and MnO2.

[0044] In some embodiments, the material can also be synthesized by a coprecipitation reaction. Specifically, metal sulfate (e.g., NiSO4, FeSO4, MnSO4) powder is dissolved in deionized water to prepare a mixed solution, and the resulting mixed solution is pumped into a reaction vessel. Simultaneously, NaOH solution is added to the reaction vessel as a precipitant and NH4OH solution is added as a pH control agent. During the coprecipitation process, the pH value is maintained between 10 and 11, and the amounts of NaOH solution and NH4OH solution are adjusted based on the pH value.

[0045] During the co-precipitation process, the temperature of the mixed solution is controlled at 40-60℃, the pH value is 10-11, and the stirring speed is 200-400rpm;

[0046] The powder obtained from coprecipitation was filtered, washed, and dried in an oven at 80-120℃ to obtain the precursor powder.

[0047] The dried precursor powder is ground and mixed with a sodium source and nitrogen oxide to obtain a mixed powder. The mixture is then heated in a muffle furnace to 300-500℃ and held for 5-10 hours to remove the water of crystallization from the precursor. The temperature is then raised to 850-950℃ and held for 10-15 hours for high-temperature sintering to obtain the high-ionic-potential layered oxide cathode material. The nitrogen oxide is selected from at least one of TiO2, MgO, and Al2O3.

[0048] Example 1: As Figure 4 As shown, the synthesis steps for preparing layered oxides using the solid-state method are as follows: Na₂CO₃, MgO, NiO, Mn₂O₃, Fe₂O₃, and TiO₂ in stoichiometric proportions are thoroughly mixed, then ball-milled at 500 rpm for eight hours to achieve a uniform and refined mixture. The mixture is then calcined in a muffle furnace at 950°C for 15 hours, followed by natural cooling to obtain NaNi. 0.1 Fe 0.1 Mn 0.5 Mg 0.02 Ti 0.28 O 2。 The calculated potential of the doped metal ions for this composition is 6.35 Å. -1 .like Figure 1 , Figure 2 As shown, the observed values ​​are... Figure 1 The plus sign "+" indicates a calculated value. Figure 1 The difference line is represented by a thick solid line. Figure 1 The locations of Bragg peaks are indicated by thin solid lines. Figure 1 The lower middle " The composite cathode was assembled with sodium metal into a 2032 coin cell, and its electrochemical performance was tested, showing excellent rate performance. Figure 6 This is a charge-discharge curve diagram of the first three cycles (Cycle 1, Cycle 2, Cycle 3) of this embodiment at a current density of 0.2C. Among them, Cycle 1 shows a slight irreversible capacity loss, which is consistent with the typical activation behavior of lithium-ion batteries.

[0049] The high degree of overlap between Cycle 2 and Cycle 3 cycle curves indicates that the battery exhibits excellent electrochemical stability and reversibility from the initial stage. The clear charge / discharge plateau and small voltage hysteresis suggest stable electrode material structure and good ion diffusion kinetics. The evolution trend of the first three curves demonstrates that this battery system possesses good cycle stability and electrochemical reversibility at low rates, laying a solid foundation for subsequent high-rate or long-cycle testing.

[0050] Figure 7 This is a rate performance diagram of the layered oxide material in this embodiment. The current densities were 0.2C, 0.5C, 1C, 2C, and 5C, with five cycles each. At a current density of 5C, the capacity remained at 116 mAh·g. -1 .

[0051] Example 2: Figure 5 As shown, spherical nickel-iron-manganese precursors prepared by co-precipitation were ground with Na₂CO₃, MgO, and TiO₂ in corresponding stoichiometric ratios in a mortar for 30 minutes to ensure uniform mixing. The mixture was then subjected to segmented calcination in a muffle furnace. First, the material was held at 450℃ for 5 hours to evaporate moisture. Then, the muffle furnace temperature was increased to 950℃ and held for 15 hours. After natural cooling, NaNi was obtained. 0.1 Fe 0.1 Mn 0.5 Mg 0.02 Ti 0.28 O2. The calculated potential of the doped metal ions for this composition is 6.35 Å. -1 .like Figure 3 As shown, the composite cathode was assembled with sodium metal into a 2032 coin cell, and the electrochemical performance was tested. It exhibited excellent rate performance, maintaining a capacity of 115 mAh·g at a current density of 5 C. -1 .

[0052] Example 3: Layered oxides were prepared using a solid-state method. Stoichiometric amounts of Na₂CO₃, NiO, Mn₂O₃, Fe₂O₃, Al₂O₃, and TiO₂ were thoroughly mixed and ball-milled at 500 rpm for eight hours to achieve homogeneity and refinement. The mixture was then calcined in a muffle furnace at 950°C for 15 hours and allowed to cool naturally to obtain NaNi. 0.1 Fe 0.1 Mn 0.5 Al 0.1 Ti 0.2 O 2。 The calculated weighted ion potential of the doped element in this composition is 6.27 Å. -1Electrochemical performance tests were conducted on 2032 coin cells assembled with this composite cathode and sodium metal, demonstrating excellent rate performance. The capacity remained at 112.5 mAh·g at a current density of 5 C. -1 .

[0053] Example 4: Layered oxides were prepared by solid-state method. Stoichiometric amounts of Na₂CO₃, NiO, Mn₂O₃, Fe₂O₃, Ga₂O₃, and TiO₂ were ball-milled at 500 rpm for eight hours, then calcined in a muffle furnace at 950°C for 15 hours, and naturally cooled to obtain NaNi. 0.1 Fe 0.1 Mn 0.5 Ga 0.1 Ti 0.2 O 2。 The calculated potential of the doped metal ions for this composition is 6.02 Å. -1 Electrochemical performance tests were conducted on 2032 coin cells assembled with this composite cathode and sodium metal, demonstrating excellent rate performance, maintaining a capacity of 109.3 mAh·g at a current density of 5C. -1 .

[0054] Example 5: Na2CO3, Ga2O3, NiO, Mn2O3, Fe2O3, V2O5, and TiO2 in stoichiometric proportions were ball-milled at 500 rpm for eight hours by co-precipitation, followed by calcination at 950°C in a muffle furnace for 15 hours and natural cooling to obtain NaN. i0.1 Fe 0.1 Mn 0.5 Ga 0.05 V 0.05 Ti 0.2 O 2。 The calculated potential of the doped metal ions for this composition is 6.76 Å. -1 Electrochemical performance tests were conducted on 2032 coin cells assembled with this composite cathode and sodium metal, demonstrating excellent rate performance, maintaining a capacity of 106.4 mAh·g at a current density of 5C. -1 .

[0055] Comparative Example 1: Stoichiometric amounts of Na₂CO₃, MgO, NiO, Mn₂O₃, Fe₂O₃, ZnO, and MgO were ball-milled at 500 rpm for eight hours via co-precipitation, followed by calcination at 950°C in a muffle furnace for 15 hours, and then naturally cooled to obtain NaNi. 0.2 Fe 0.2 Mn 0.4 Mg 0.1 Zn 0.1 O 2。 The calculated potential of the doped metal ions for this composition is 2.74 Å.-1 Electrochemical performance tests were conducted on 2032 coin cells assembled with this composite cathode and sodium metal. The cells exhibited poor rate performance, maintaining a capacity of only 67.3 mAh·g at a current density of 5 C. -1 .

[0056] Table 1 compares the electrochemical performance of materials in existing technologies.

[0057] Table 1

[0058]

[0059] Table 2 compares the electrochemical performance of Examples 1-5 and Comparative Example 1.

[0060] Table 2

[0061]

[0062] As shown in Table 2, the weighted ion potential of the doped elements in Examples 1-5 exceeds the critical value of 6 Å. -1 Furthermore, it can still maintain 100 mAh·g at a high current density of 5C. -1 The high capacity. However, the weighted ion potential of the doped element in Comparative Example 1 did not reach 6 Å. -1 (only 2.74 Å) -1 Therefore, its rate performance is not ideal, with only 67.3 mAh·g at 5C current conditions. -1 The capacity.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, any equivalent substitutions, structural combinations, or algorithmic tweaks made without departing from the core mechanism and principles of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements, characterized in that, Its general structural formula is NaM m N n O2, where m and n are in the range of 0 to 1 and satisfy m+n=1, M is an element that participates in charge compensation and is selected from at least one of Ni, Fe, Mn, and Co; Na is a matrix element; N is an element that does not participate in charge compensation and is selected from at least one of Mg, Ti, V, Cr, B, Al, and Ga.

2. The sodium-ion battery layered oxide cathode material based on a combination of high ionic potential doped elements according to claim 1, characterized in that, The element N is a combination of high ionic potential doped elements, whose weighted ionic potential The calculation formula is as follows: ， in, The ionic potential is expressed as φ = z / r, where z is the electric charge and r is the ionic radius. Indicates the first The number of moles of element N. The weighted ionic potential represents the total number of moles of N element. The value is greater than 6 Å -1 .

3. The sodium-ion battery layered oxide cathode material based on a combination of high ionic potential doped elements according to claim 1, characterized in that, The average particle size of the cathode material is between 3 μm and 7 μm.

4. A method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements as described in claim 1, characterized in that, The cathode material is synthesized by solid-state reaction. Specifically, sodium source and metal oxide raw materials are weighed according to stoichiometric ratio, mixed evenly, and then ball-milled for 5-8 hours to obtain precursor powder. The precursor powder is placed in a muffle furnace and calcined at 850℃-950℃ for 10-15 hours in air atmosphere to obtain the sodium-ion battery layered oxide cathode material.

5. The method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements according to claim 4, characterized in that, The sodium source is Na2CO3.

6. The method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements according to claim 4, characterized in that, The metal oxide raw material includes oxides of element M and oxides of element N, wherein the oxide of element M includes at least one of NiO, Fe2O3, and MnO2.

7. A method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements as described in claim 1, characterized in that, The positive electrode material is synthesized by a co-precipitation reaction. Specifically, metal sulfate powder is dissolved in deionized water to prepare a mixed solution, and the resulting mixed solution is pumped into a reaction vessel. At the same time, NaOH solution is added to the reaction vessel as a precipitant and NH4OH solution is added as a pH control agent. During the co-precipitation process, the pH value is maintained between 10 and 11, and the amounts of NaOH solution and NH4OH solution are adjusted based on the pH value. During the co-precipitation process, the temperature of the mixed solution is controlled at 40-60℃, the pH value is 10-11, and the stirring speed is 200-400rpm; The powder obtained from coprecipitation was filtered, washed, and dried in an oven at 80-120℃ to obtain the precursor powder. The dried precursor powder is ground and mixed with sodium source and N element oxide to obtain mixed powder. The muffle furnace is heated to 300-500℃ and held for 5-10h to remove the water of crystallization in the precursor. The temperature is then raised to 850-950℃ and held for 10-15h for high-temperature sintering to obtain the high ionic potential layered oxide cathode material.

8. The method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements according to claim 7, characterized in that, The metal sulfate is selected from at least one of NiSO4, FeSO4, and MnSO4.

9. The method for preparing a layered oxide cathode material for sodium-ion batteries based on a combination of high ionic potential doped elements according to claim 7, characterized in that, The N element oxide is selected from at least one of TiO2, MgO, and Al2O3.

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