Fluorine-containing layered oxide positive electrode material for sodium ion battery and preparation method of fluorine-containing layered oxide positive electrode material

Abstract

The invention relates to a fluorine-containing layered oxide positive electrode material for a sodium ion battery and a preparation method thereof, the chemical general formula of the fluorine-containing layered oxide positive electrode material is NazMxTO2-yFy or NauMxT1-xO2-yFy, y is more than or equal to 0.04 and less than or equal to 0.1, xm-y is equal to 0, m is the valence of M, z is more than or equal to 0.8 and less than or equal to 1.0, u is more than or equal to 0.9 and less than or equal to 1.0, and z and u meet the charge balance of the chemical general formula; t is selected from at least one of Ni, Co, Fe, Mn, Cu and Ti; when the chemical general formula is NazMxTO2-yFy, M is selected from at least one of Ca, Sr and Mg; when the chemical general formula is NauMxT (1-x) O (2-y) Fy, M is selected from at least one of Cu, Co, Zr and Fe and is not the same as T; the fluorine-containing layered oxide positive electrode material is prepared by mixing MxFy and a T source material and then carrying out gradient calcination.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical cells, and in particular relates to a fluorine-containing layered oxide positive electrode material for sodium ion batteries and a preparation method thereof. Background Art

[0002] As energy and environmental challenges become increasingly severe, the demand for large-scale energy storage is increasing. However, the scarcity and uneven global distribution of lithium resources have hindered the widespread application of lithium-ion batteries in this field. However, sodium-ion batteries, which share the same operating principle as lithium-ion batteries, are considered promising for large-scale energy storage due to their abundant sodium resources and low cost.

[0003] Among the many cathode materials for sodium-ion batteries, layered oxide cathodes have the characteristics of high capacity, low pollution and easy preparation, and are considered to be an ideal cathode material suitable for large-scale energy storage applications. + / Na standard electrode potential compared to Li + The standard electrode potential of lithium-ion batteries (Li) is low at ~0.3V, and the molar mass of sodium is greater, resulting in a lower energy density for sodium-ion batteries than for lithium-ion batteries. Therefore, increasing the output voltage of sodium-ion batteries is the key to increasing their energy density. However, layered cathode materials face serious interface problems under high pressure. Transition metals are easily dissolved and segregated on the surface, which degrades the surface structure and forms a rock salt phase. In addition, the activity of transition metal ions and oxygen increases under high pressure. On the one hand, high-valent transition metal ions catalyze the decomposition of the electrolyte, and on the other hand, the surface of the material oxidizes and releases oxygen, which not only destroys the structure of the material but also poses a safety hazard. In addition to the serious interface problems under high pressure, layered oxide cathodes also undergo irreversible phase transitions under high pressure, resulting in the destruction of the bulk structure and deterioration of cycle performance.

[0004] Chinese patent CN113764669B discloses a layered oxide cathode material for a high-voltage sodium-ion battery. The patent uses lithium fluoride doping to improve material stability. However, due to the low melting point (845°C) and vaporization enthalpy (146.8 kJ / mol) of lithium fluoride, and considering the thermal volatilization effect at high temperatures, the fluorine doping amount is less than its initial stoichiometric ratio, which in turn affects the structure and performance of the material, especially its stability under high pressure.

[0005] Chinese patent CN114678509B discloses a sodium-ion battery layered cathode material in situ coated with fluoride oxide and a preparation method thereof. The preparation method in this patent is solid-phase coating, using sodium fluoride for in-situ coating. However, sodium fluoride forms a low eutectic point (694°C) with sodium carbonate, and the evaporation enthalpy of sodium fluoride is low (176.2 kJ / mol), causing large amounts of fluorine and sodium to volatilize, thereby affecting the structure and performance of the material. Moreover, coating with sodium fluoride alone is difficult to solve the problem of irreversible phase change of the bulk phase under high pressure. Summary of the Invention

[0006] In order to solve the problem that the electrochemistry of the sodium ion battery cathode material in the prior art cannot meet the actual requirements, especially the stability under high pressure, the present invention uses fluoride with high vaporization enthalpy, cation M and anion F - The above problems were solved by the strategy of dual doping and staged calcination, and a fluorine-containing layered oxide positive electrode material with fluorine surface enrichment doping and uniform cation doping was obtained, which improved its interface stability at high voltage and solved the problem of irreversible phase change of layered oxide positive electrode material under high voltage, thereby improving its energy density and cycle stability.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A fluorine-containing layered oxide cathode material for sodium ion batteries, the general chemical formula of which is Na z M x TO 2-y F y Or Na u M x T 1-x O 2-y F y , where 0.04≤y≤0.1, xm-y=0, m is the valence of M, 0.8≤z≤1.0, and z satisfies Na z M x TO 2-y F y Charge balance, 0.9≤u≤1.0, and u satisfies Na u M x T 1-x O 2-y F y Charge balance; T is a transition metal, selected from at least one of Ni, Co, Fe, Mn, Cu, and Ti; when the chemical formula is Na z M x TO 2-y F y When M is an alkaline earth metal, selected from at least one of Ca, Sr, and Mg; when the chemical formula is Na u M x T 1-x O2-y F y When M is a transition metal, selected from at least one of Cu, Co, Zr, and Fe, and is different from T; the fluorine-containing layered oxide positive electrode material is obtained by replacing M x F y It is mixed with T source material and calcined at 300-600°C, and then mixed with sodium source material and calcined at 800-1000°C.

[0009] The fluorine-containing layered oxide cathode material of the present invention has a stable layered structure. z M x TO 2-y F y When the chemical formula is Na u M x T 1-x O 2-y F y When , the M element is doped at the transition metal layer site.

[0010] In the raw materials for preparing the fluorine-containing layered oxide positive electrode material of the present invention, the M source and the F source come from the same compound M x F y , that is, xm-y=0 in the general chemical formula, where m is the valence of M.

[0011] Preferably, 0.06≤y≤0.08, for example, y=0.06, y=0.07, y=0.08.

[0012] Preferably, the T includes at least two of Ni, Fe, Mn, Cu, and Ti. Preferably, T includes Ni, Fe, Mn, Cu, and Ti at the same time, and the molar ratio of Ni, Fe, Mn, Cu, and Ti is 1:(0.8-1.2):(0.8-1.2):(0.1-0.2):(0.1-0.2).

[0013] Preferably, the chemical formula is Na z M x TO 2-y F y , that is, the M element is doped in the Na layer; more preferably, the chemical formula is Na z M x TO 2-y F y When Ca or Mg is doped in the Na layer, the atomic radius of Ca or Mg is closer to that of Na, thereby reducing the degree of structural distortion caused by doping and acting as a structural pillar, making the structure of the fluorine-containing layered oxide cathode material more stable, thereby improving its cycle stability.

[0014] Furthermore, the chemical formula is Nau M x T 1-x O 2-y F y When M is selected from at least one of Cu, Co, and Fe, and is different from T. Cu, Co, or Fe has an atomic radius closer to that of T. When doped at the transition metal layer site, it can reduce the degree of structural distortion caused by doping, making the structure of the fluorine-containing layered oxide positive electrode material more stable, thereby improving its cycle performance.

[0015] Furthermore, the T source material is at least one of T oxides, sulfates, nitrates, carbonates, acetates, oxalates and hydrated compounds thereof; and the sodium source material is selected from at least one of sodium carbonate, sodium bicarbonate, sodium acetate, sodium oxalate, sodium hydroxide, sodium oxide, sodium peroxide and sodium nitrite.

[0016] Furthermore, the calcination time at 300-600° C. is 12-48 hours; the calcination time at 800-1000° C. is 12-48 hours.

[0017] In the preferred technical solution of the present invention, the chemical formula of the fluorine-containing layered oxide positive electrode material for sodium ion batteries is Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 、Na 0.88 Mg 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.0 5O 1.94 F 0.06 Or Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08 .

[0018] The fluorine-containing layered oxide positive electrode material for sodium ion batteries of the present invention is a layered flaky particle with an average particle size of 1 to 5 μm.

[0019] In a second aspect, the present invention also provides a method for preparing the fluorine-containing layered oxide positive electrode material for a sodium ion battery, comprising the following steps:

[0020] (S1) According to the stoichiometric ratio corresponding to the chemical formula, M x F y , T source materials are ball-milled and mixed, and then calcined at 300-600° C. for 12-48 hours, and cooled to room temperature to obtain a calcined product;

[0021] (S2) The sodium source material in an amount of 1.01 to 1.03 times the stoichiometric ratio corresponding to the chemical formula is mixed with the above calcined product by ball milling, and then calcined at 800 to 1000° C. for 12 to 48 hours, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material.

[0022] The present invention utilizes cation M and anion F - The double-doping method was used to prepare a layered oxide material with fluorine-rich surface and uniformly doped cation M. The surface fluorine-rich can effectively inhibit the interface problems under high pressure, such as transition metal dissolution, electrolyte decomposition and gas production; the uniformly doped cation M can effectively inhibit the irreversible phase change problem under high pressure; that is, through the cation M and anion F - The dual doping solves the interface and irreversible phase transition problems faced by layered oxides under high pressure, significantly improving their energy density and cycle stability. At the same time, in the chemical formula of the fluorine-containing layered oxide positive electrode material of the present invention, xm-y=0, m is the valence of M, that is, the M source and the F source come from the same compound M x F y Compared with conventional doping F sources (such as LiF, NaF), M x F y The vaporization enthalpy of the sodium source is higher, so less volatilization occurs during the calcination process, thereby avoiding the eutectic effect between the sodium source and the fluoride, reducing the large amount of volatilization of the sodium source and the fluorine source during the calcination process, and making the fluorine doping more effective and closer to the designed stoichiometric ratio.

[0023] In addition, the present invention adopts a staged calcination process, that is, first calcining at a low temperature of 300-600°C without adding a sodium source, and then calcining at a high temperature of 800-1000°C with the addition of a sodium source. The inventors have found through research that the step-by-step calcination can reduce the volatilization of the sodium source and the fluorine source during the calcination process, which is conducive to the doping of cations M into the bulk phase, thereby improving the structural stability of the material. The possible reason is that the low-temperature calcination of M x F yWhen the T source material is used, it is conducive to the formation of a spinel phase structure, which further avoids the volatilization of fluorine and allows the metal M to stably enter the bulk phase; when calcined at a high temperature, it is conducive to allowing sodium to enter the bulk phase to form a layered structure, which is conducive to improving the crystallinity and thus improving the structural stability of the material. In the present invention, the actual ratio of the sodium source material is slightly higher than its stoichiometric ratio to supplement the volatilization of the sodium source material at high temperature; in the prior art, the sodium source is generally excessive by more than 5%, but the excess sodium source will cause residual alkali to form on the surface of the obtained layered oxide positive electrode material, which must be eliminated later; while in the present invention, M is used. x F y The step-by-step calcination method can reduce the usage of sodium source materials. The sodium source only needs to be in excess of 1-3%, and there is no need to eliminate the residual alkali in the subsequent step.

[0024] Furthermore, in step (S1) and step (S2), the ball milling mixing conditions are: ball mill speed 200-800 rpm, preferably 300-600 rpm, time 1-10 h, preferably 3-7 h; the calcination atmosphere is at least one of oxygen and air.

[0025] In a third aspect, the present invention further provides a sodium ion battery, wherein the raw materials for preparing the positive electrode thereof include the above-mentioned fluorine-containing layered oxide positive electrode material.

[0026] Furthermore, the raw materials for preparing the positive electrode also include a conductive agent and a binder; the mass ratio of the fluorine-containing layered oxide positive electrode material, the conductive agent, and the binder is (7-9):(0.5-2):(0.5-2), preferably (8-9):(0.5-1):(0.5-1).

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention uses cation M and anion F - By dual doping and step-by-step calcination, a layered oxide material with surface rich fluorine and uniformly doped cation M was obtained, which solved the problem of irreversible phase change of layered oxide positive electrode materials under high voltage and improved its interface stability under high voltage, thereby improving its energy density and cycle stability.

[0029] 2. The M source and F source of the present invention are derived from the same compound M x F y , and M x F yThe higher the enthalpy of vaporization, the less volatile it is during the calcination process. This avoids the eutectic effect between the sodium source and the fluoride, reduces the large-scale volatilization of the sodium and fluorine sources during the calcination process, and makes the fluorine doping more effective. In the present invention, the fluorine doping amount reaches 97% to 99% of the theoretical amount. In addition, the use of a step-by-step calcination method in the present invention further reduces the amount of sodium source material used. Only a 1 to 3% excess of sodium source is required to reach 97% to 99% of the theoretical amount, and no subsequent step of eliminating residual alkali is required.

[0030] 3. The fluorine-containing layered oxide cathode material prepared by the present invention has good cycle stability, especially excellent cycle stability under high-voltage conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the XRD spectrum of the fluorine-containing layered oxide positive electrode material prepared in Example 1.

[0032] Figure 2 This is the SEM spectrum of the fluorine-containing layered oxide positive electrode material prepared in Example 1.

[0033] Figure 3 This is the XPS etching pattern of the fluorine-containing layered oxide positive electrode material prepared in Example 1.

[0034] Figure 4 Graph showing the cycle performance of the sodium ion batteries prepared in Application Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0035] The present invention will be described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0036] The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.

[0037] Example 1 - Preparation of Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 (Conforms to the chemical formula Na z M x TO 2-y F y , wherein M is Ca, and T includes Ni, Fe, Mn, Cu, and Ti. Specifically, T is Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti0.05 , z=0.88, y=0.06, x=0.03)

[0038] (S1) by chemical formula Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.03 mol of CaF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80 ° C. in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450 ° C. at a heating rate of 5 ° C. / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0039] (S2) 0.90 mol (by Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 900 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 .

[0040] Example 2 - Preparation of Na 0.88 Mg 0.03 Ni0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06

[0041] The rest is the same as Example 1, except that: M is Mg, that is, MgF2 is used instead of CaF2 in step (S1); specifically:

[0042] (S1) by chemical formula Na 0.88 Mg 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.03 mol of MgF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80 ° C in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 500 ° C at a heating rate of 5 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0043] (S2) 0.90 mol (by Na 0.88 Mg 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball milling was performed for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 950 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.88 Mg 0.03 Ni 0.3 Fe 0.3 Mn0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 .

[0044] Example 3 - Preparation of Na 0.88 Ca 0.03 Ni 0.3 Fe 0.4 Mn 0.3 O 1.94 F 0.06

[0045] The rest is the same as Example 1, except that the type of T is different. T includes Ni, Fe, and Mn. Specifically, T is Ni 0.3 Fe 0.4 Mn 0.3 ; Specifically:

[0046] (S1) by chemical formula Na 0.88 Ca 0.03 Ni 0.3 Fe 0.4 Mn 0.3 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.03 mol of CaF2, 0.3 mol of NiO, 0.2 mol of Fe2O3, 0.3 mol of MnO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 600 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80°C in a vacuum oven for 12 h to obtain a mixture A; then the mixture A was placed in a muffle furnace, heated to 600°C at a heating rate of 5°C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0047] (S2) 0.90 mol (by Na 0.88 Ca 0.03 Ni 0.3 Fe 0.4 Mn 0.3 O 1.94 F 0.06 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 800 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 24 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries.0.8 8Ca 0.03 Ni 0.3 Fe 0.4 Mn 0.3 O 1.94 F 0.06 .

[0048] Example 4 - Preparation of Na 0.88 Sr 0.03 Fe 0.4 Co 0.6 O 1.94 F 0.06

[0049] The rest is the same as Example 1, except that the types of M and T are different, M is Sr, T includes Fe and Co, specifically, T is Fe 0.4 Co 0.6 ; Specifically:

[0050] (S1) by chemical formula Na 0.88 Sr 0.03 Fe 0.4 Co 0.6 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.03 mol of SrF2, 0.2 mol of Fe2O3, 0.3 mol of Co2O3 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80°C in a vacuum oven for 12 h to obtain a mixture A; then the mixture A was placed in a muffle furnace, and the temperature was increased to 300°C at a heating rate of 5°C / min in an air atmosphere, kept at this temperature for 24 h, and cooled to room temperature to obtain a calcined product;

[0051] (S2) 0.90 mol (by Na 0.88 Sr 0.03 Fe 0.4 Co 0.6 O 1.94 F 0.06 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball milling was performed for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 1000 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.88 Sr 0.03Fe 0.4 Co 0.6 O 1.94 F 0.06 .

[0052] Example 5 - Preparation of Na 0.92 Ca 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.96 F 0.04

[0053] The rest is the same as Example 1, except that: z = 0.92, y = 0.04, then x = 0.02, and accordingly according to the chemical formula Na 0.92 Ca 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.98 F 0.04 The corresponding stoichiometric ratio of ingredients is as follows:

[0054] (S1) by chemical formula Na 0.92 Ca 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.96 F 0.04 Corresponding to the stoichiometric ratio of each element, 0.02 mol of CaF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 5 h. After the ball milling was completed, the mixture was dried at 80 ° C. in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450 ° C. at a heating rate of 5 ° C. / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0055] (S2) 0.94 mol (by Na 0.92 Ca 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.96F 0.04 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 900 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.92 Ca 0.01 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.98 F 0.02 .

[0056] Example 6 - Preparation of Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08

[0057] The rest is the same as Example 1, except that: z = 0.84, y = 0.08, then x = 0.04, and accordingly according to the chemical formula Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08 The corresponding stoichiometric ratio of ingredients is as follows:

[0058] (S1) by chemical formula Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08Corresponding to the stoichiometric ratio of each element, 0.04 mol of CaF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 8 h. After the ball milling was completed, the mixture was dried at 80°C in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450°C at a heating rate of 5°C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0059] (S2) 0.85 mol (Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 800 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.92 F 0.08 .

[0060] Example 7 - Preparation of Na 0.8 Ca 0.05 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 F 0.1

[0061] The rest is the same as Example 1, except that: z = 0.8, y = 0.1, then x = 0.05, and accordingly according to the chemical formula Na 0. 8Ca 0.05 Ni0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 F 0.1 The corresponding stoichiometric ratio of ingredients is as follows:

[0062] (S1) by chemical formula Na 0.8 Ca 0.05 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 F 0.1 Corresponding to the stoichiometric ratio of each element, 0.05 mol of CaF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 8 h. After the ball milling was completed, the mixture was dried at 80°C in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450°C at a heating rate of 5°C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0063] (S2) 0.81 mol (according to Na 0.8 Ca 0.05 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 F 0.1 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 800 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.8 Ca 0.05 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 F0.1 .

[0064] Example 8 - Preparation of Na 0.96 Co 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.03 Ti 0.04 O 1.94 F 0.06 (Conforms to the chemical formula Na u M x T 1-x O 2-y F y , wherein M is Co, and T includes Ni, Fe, Mn, Cu, and Ti. Specifically, T is Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.04 Ti 0.04 , u=0.96, y=0.06, x=0.03)

[0065] (S1) by chemical formula Na 0.96 Co 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.04 Ti 0.04 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.02 mol of CoF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.04 mol of CuO, 0.04 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80 ° C. in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450 ° C. at a heating rate of 5 ° C. / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0066] (S2) 0.98 mol (i.e., Na 0.96 Co 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.04 Ti 0.04 O 1.94 F 0.06The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball milling was performed for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 900 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.98 Co 0.02 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.04 Ti 0.04 O 1.94 F 0.06 .

[0067] Example 9 - Preparation of Na 0.91 Zr 0.02 Ni 0.33 Fe 0.33 Mn 0.32 O 1.92 F 0.08 (Conforms to the chemical formula Na u M x T 1-x O 2- y F y , wherein M is Zr, T includes Ni, Fe, Mn, specifically, T is Ni 0.3 Fe 0.3 Mn 0.25 , u=0.91, y=0.06, x=0.03)

[0068] (S1) by chemical formula Na 0.91 Zr 0.02 Ni 0.33 Fe 0.33 Mn 0.32 O 1.92 F 0.08 Corresponding to the stoichiometric ratio of each element, 0.02 mol of ZrF4, 0.33 mol of NiO, 0.165 mol of Fe2O3, 0.32 mol of MnO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 6 h. After the ball milling was completed, the mixture was dried at 80°C in a vacuum oven for 12 h to obtain a mixture A; then the mixture A was placed in a muffle furnace, heated to 500°C at a heating rate of 5°C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0069] (S2) 0.93 mol (i.e., Na 0.91 Zr 0.02 Ni 0.33 Fe 0.33 Mn 0.32 O 1.92 F 0.08 The mixture was placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 400 rpm, the forward and reverse modes were used, and the ball mill was milled for 5 h. After the ball milling was completed, the mixture was dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B was placed in a muffle furnace, heated to 900 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.91 Zr 0.02 Ni 0.33 Fe 0.33 Mn 0.32 O 1.92 F 0.08 .

[0070] Comparative Example 1---Preparation of NaNi 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O2

[0071] The rest is the same as in Example 1, except that no CaF2 is used, that is, no cation Ca is used. 2+ and anion F - Double doping; specifically:

[0072] (S1) According to the chemical formula NaNi 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 The stoichiometric ratio of each element corresponding to O2 was calculated, and 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was performed for 8 h. After the ball milling was completed, the mixture was dried at 80 ° C in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450 ° C at a heating rate of 5 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0073] (S2) 1.02 mol (NaNi 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 NaHCO3 (based on the stoichiometric ratio of Na element corresponding to O2, with an excess of 2.0% of sodium source) is mixed with the calcined product obtained in step (S1) and a small amount of ethanol and placed in a ball mill, the ball-to-material ratio is controlled to 20:1, the ball mill speed is set to 400 rpm, the forward and reverse modes are used, and the ball mill is milled for 5 hours. After the ball milling is completed, the mixture is dried at 80°C in a vacuum oven for 12 hours to obtain a mixture B; the mixture B is then placed in a muffle furnace, heated to 900°C at a heating rate of 8°C / min in an air atmosphere, kept warm for 12 hours, and cooled to room temperature to obtain a layered oxide positive electrode material NaNi for sodium ion batteries. 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O2.

[0074] Comparative Example 2

[0075] The rest is the same as Example 1, except that the Ca source and the F source are not derived from the same compound CaF2, that is, the Ca source is derived from CaO, and the F source is derived from NaF, specifically:

[0076] (S1) by chemical formula Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 Corresponding to the stoichiometric ratio of each element, 0.03 mol of CaO, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2, 0.06 mol of NaF and 1 times the total mass of ethanol of the above materials were mixed and placed in a ball mill, the ball-to-material ratio was controlled to be 20:1, the ball mill speed was set to 500 rpm, the forward and reverse modes were used, and the ball milling was carried out for 8 h. After the ball milling was completed, the mixture was dried at 80 ° C in a vacuum oven for 12 h to obtain a mixture A; the mixture A was then placed in a muffle furnace, heated to 450 ° C at a heating rate of 5 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a calcined product;

[0077] (S2) 0.84 mol (i.e., Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu0.05 Ti 0.05 O 1.94 F 0.06 The corresponding Na element stoichiometric ratio is calculated, and the sodium source is in excess of 2.3%, where the partial Na source provided by NaF is deducted. The NaHCO3 is mixed with the calcined product obtained in step (S1) and a small amount of ethanol and placed in a ball mill, and the ball-to-material ratio is controlled to 20:1. The ball mill speed is set to 400 rpm, in forward and reverse modes, and the ball milling is performed for 5 h. After the ball milling is completed, the mixture is dried in a vacuum oven at 80 ° C for 12 h to obtain a mixture B; the mixture B is then placed in a muffle furnace, heated to 900 ° C at a heating rate of 8 ° C / min in an air atmosphere, kept warm for 12 h, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 .

[0078] Comparative Example 3

[0079] The rest is the same as Example 1, except that no staged calcination is performed. Specifically:

[0080] (S1) by chemical formula Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 The corresponding stoichiometric ratio of each element is 0.90 mol (i.e., Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06The corresponding Na element stoichiometric ratio is calculated, and the sodium source is 2.3% excess) of NaHCO3, 0.03 mol of CaF2, 0.3 mol of NiO, 0.15 mol of Fe2O3, 0.3 mol of MnO2, 0.05 mol of CuO, 0.05 mol of TiO2 and 1 times the total mass of the above materials are mixed and placed in a ball mill, the ball-to-material ratio is controlled to 20:1, the ball mill speed is set to 500 rpm, the forward and reverse modes are used, and the ball milling is performed for 10 hours. After the ball milling is completed, the mixture is dried at 80°C in a vacuum oven for 12 hours to obtain a mixture A; the mixture A is then placed in a muffle furnace, heated to 900°C at a heating rate of 6°C / min in an air atmosphere, kept warm for 24 hours, and cooled to room temperature to obtain a fluorine-containing layered oxide positive electrode material Na for sodium ion batteries. 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 .

[0081] Application Example 1

[0082] The layered oxide positive electrode material prepared in Example 1 was pressed into small discs with a diameter of 10 mm, and then placed in a muffle furnace for calcination at a heating rate of 5°C / min. After reaching 950°C, it was kept warm for 15 hours, cooled to room temperature, and then transferred to a hand box for standby use; then the pressed fluorine-containing layered oxide positive electrode material, conductive additive SP, and binder PVDF were mixed in 80 parts by mass, 10 parts by mass, and 10 parts by mass, dissolved in the solvent NMP, and stirred to obtain a uniform slurry. The slurry was then evenly coated on a carbon-coated aluminum foil with a 200μm scraper, dried, and sliced to obtain a pole piece; finally, a button battery was assembled using the obtained pole piece as the positive electrode, the metal sodium sheet as the negative electrode, the glass fiber as the diaphragm, and 1mol / L NaClO4 (PC+5%FEC) as the electrolyte.

[0083] Application Example 2-9

[0084] The rest is the same as Application Example 1, except that the layered oxide positive electrode materials are prepared from Examples 2-9, respectively.

[0085] Comparative Application Examples 1-3

[0086] The rest is the same as Application Example 1, except that the layered oxide positive electrode materials are prepared from Comparative Examples 1-3 respectively.

[0087] Testing and Analysis

[0088] 1. Structural analysis

[0089] The layered cathode materials prepared in the examples and comparative examples were subjected to XRD, SEM and XPS tests. The XRD spectrum of the fluorine-containing layered oxide cathode material prepared in Example 1 is as follows: Figure 1 As shown, the SEM spectrum of the fluorine-containing layered oxide positive electrode material prepared in Example 1 is as follows Figure 2 As shown, the XPS etching pattern of the fluorine-containing layered oxide cathode material prepared in Example 1 is as follows: Figure 3 shown.

[0090] from Figure 1 It can be seen that the fluorine-containing layered oxide cathode material Na prepared in Example 1 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 It still maintains the structure of the O3 phase and can still be classified as the R-3m type space group, without obvious impurities. Figure 2 It can be seen that the particle size of the fluorine-containing layered oxide positive electrode material is relatively uniform, flaky, with a particle size of 1 to 5 μm and a relatively smooth surface. Figure 3 It can be seen that the signal of F gradually increases from the bulk to the surface, indicating that F is more enriched on the surface; while the signals of cation M in the bulk and surface are basically the same, indicating that cation M is evenly distributed in the entire system.

[0091] 2. Sodium and fluoride content test

[0092] The sodium content and fluorine content of the layered cathode materials prepared in the examples and comparative examples were tested by inductively coupled plasma mass spectrometry (ICP-MS). The specific test data are shown in Table 1.

[0093] Table 1 Fluoride content and sodium content test

[0094]

[0095]

[0096] As can be seen from Table 1, the fluorine content and sodium content of the fluorine-containing layered oxide positive electrode material prepared in the embodiment of the present invention are close to the theoretical values, and the fluorine content and sodium content are both about 97% to 99% of the theoretical content, indicating that the sodium source and fluorine source are less volatile.

[0097] In Comparative Example 1, since no cationic Ca 2+ and anion F -, so the obtained layered oxide positive electrode material does not contain fluorine, and the sodium content is also close to the theoretical value, but the subsequent electrochemical performance is poor (as shown in Table 2). In Comparative Example 2, the Ca source and the F source are not derived from the same compound CaF2, and the fluorine content and sodium content of the obtained layered oxide positive electrode material are both lower than the theoretical value, about 72% to 75% of the theoretical value. This is because when sodium fluoride is used as a fluorine source, it will form a low eutectic mixture with sodium bicarbonate of the sodium source, which aggravates the volatilization of the sodium source and the fluorine source during the calcination process. Comparative Example 3 did not perform staged calcination, and the fluorine content and sodium content of the obtained layered oxide positive electrode material were also lower than the theoretical value, about 83% to 85% of the theoretical value.

[0098] 3. Electrochemical performance test

[0099] The electrochemical performance of the batteries assembled in the application examples and comparative application examples was tested. The specific conditions were: the positive electrode was activated for 3 cycles at a current density of 15mA / g (15mA / g=0.1C) in the voltage range of 2.0-4.2V, and then charged and discharged at a current density of 150mA / g (150mA / g=1C). The cycle performance of the sodium ion batteries prepared in application example 1 and comparative application example 1 is shown in the figure. Figure 4 The specific test results are shown in Table 2.

[0100] Table 2 Electrochemical performance

[0101]

[0102] The first-cycle discharge capacity* refers to the capacity at the 4th cycle. The capacity retention rate after 400 cycles** actually refers to the capacity after 404 cycles compared to the 4th cycle. The first 3 cycles belong to the formation process.

[0103] As can be seen in Table 2, the capacity retention of sodium-ion batteries assembled with the fluorine-containing layered oxide cathode materials prepared in Examples of the present invention after 400 cycles is significantly improved. In particular, in Application Examples 1, 2, and 6, the capacity retention after 400 cycles reaches over 91%, significantly higher than in the comparative application examples.

[0104] The present invention provides a fluorine-containing layered oxide positive electrode material and an application thereof in a sodium ion battery. The contribution to the prior art lies in avoiding the volatilization problem caused by the low eutectic state of the fluorine source and the sodium source and the low vaporization enthalpy fluorine source, and simultaneously achieving dual-site doping, effectively solving the interface and irreversible phase change problems under high-voltage cycling, and significantly improving the electrochemical performance of sodium ion batteries under high voltage.

Claims

1. A fluorine-containing layered oxide cathode material for a sodium ion battery, characterized in that: Its chemical formula is Na z M x TO 2- y F y Or Na u M x T 1-x O 2-y F y , where 0.04≤y≤0.1, xm-y=0, m is the valence of M, 0.8≤z≤1.0, and z satisfies Na z M x TO 2-y F y Charge balance, 0.9≤u≤1.0, and u satisfies Na u M x T 1-x O 2-y F y Charge balance; T is a transition metal, selected from at least one of Ni, Co, Fe, Mn, Cu, and Ti; when the chemical formula is Na z M x TO 2-y F y When M is an alkaline earth metal, selected from at least one of Ca, Sr, and Mg; when the chemical formula is Na u M x T 1-x O 2-y F y When M is a transition metal, selected from at least one of Cu, Co, Zr, and Fe, and is different from T; the fluorine-containing layered oxide positive electrode material is obtained by replacing M x F y It is mixed with T source material and calcined at 300-600°C, and then mixed with sodium source material and calcined at 800-1000°C.

2. The fluorine-containing layered oxide positive electrode material for sodium ion batteries according to claim 1, characterized in that 0.06≤y≤0.08。 3. The fluorine-containing layered oxide cathode material for sodium ion batteries according to claim 1, wherein The T includes at least two of Ni, Fe, Mn, Cu, and Ti. Preferably, T includes Ni, Fe, Mn, Cu, and Ti at the same time, and the molar ratio of Ni, Fe, Mn, Cu, and Ti is 1:(0.8-1.2):(0.8-1.2):(0.1-0.2):(0.1-0.2).

4. The fluorine-containing layered oxide positive electrode material for sodium ion batteries according to claim 1, characterized in that The chemical formula is Na z M x TO 2-y F y , that is, the M element is doped in the Na layer; preferably, the chemical formula is Na z M x TO 2-y F y When M is selected from Ca or Mg.

5. The fluorine-containing layered oxide positive electrode material for sodium ion batteries according to claim 1, characterized in that The chemical formula is Na u M x T 1-x O 2-y F y When M is selected from at least one of Cu, Co, and Fe, and is different from T.

6. The fluorine-containing layered oxide cathode material for sodium ion batteries according to claim 1, characterized in that The T source material is at least one of T oxides, sulfates, nitrates, carbonates, acetates, oxalates and hydrated compounds thereof; the sodium source material is selected from at least one of sodium carbonate, sodium bicarbonate, sodium acetate, sodium oxalate, sodium hydroxide, sodium oxide, sodium peroxide and sodium nitrite.

7. The fluorine-containing layered oxide cathode material for sodium ion batteries according to claim 1, wherein: The calcination time at 300-600° C. is 12-48 hours; the calcination time at 800-1000° C. is 12-48 hours.

8. The fluorine-containing layered oxide cathode material for sodium ion batteries according to claim 1, wherein: The chemical formula of the fluorine-containing layered oxide positive electrode material for sodium ion batteries is Na 0.88 Ca 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.9 4F 0.06 、Na 0.88 Mg 0.03 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.05 O 1.94 F 0.06 Or Na 0.84 Ca 0.04 Ni 0.3 Fe 0.3 Mn 0.3 Cu 0.05 Ti 0.0 5O 1.92 F 0.08 .

9. The fluorine-containing layered oxide cathode material for sodium ion batteries according to claim 1, wherein: The fluorine-containing layered oxide positive electrode material for sodium ion batteries is a layered flaky particle with an average particle size of 1 to 5 μm.

10. The method for preparing a fluorine-containing layered oxide cathode material for a sodium ion battery according to any one of claims 1 to 9, characterized in that: The following steps are involved: (S1) According to the stoichiometric ratio corresponding to the chemical formula, M x F y , T source materials are ball-milled and mixed, and then calcined at 300-600° C. for 12-48 hours, and cooled to room temperature to obtain a calcined product; (S2) ball-milling the calcined product with a sodium source material in an amount of 1.01 to 1.03 times the stoichiometric ratio corresponding to the chemical formula, calcining the mixture at 800 to 1000° C. for 12 to 48 hours, and cooling the mixture to room temperature to obtain a fluorine-containing layered oxide cathode material; Preferably, in step (S1) and step (S2), the ball milling mixing conditions are: ball mill speed 200-800 rpm, time 1-10 h; the calcination atmosphere is at least one of oxygen and air.

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