KTP type sodium-rich phosphate positive electrode material as well as preparation method and application thereof

Abstract

The invention discloses a KTP type sodium-rich phosphate positive electrode material and a preparation method and application thereof, the chemical formula of the phosphate positive electrode material is NaxV1-yTyPO4F1-zOz, 1 < x < = 2, 0 < y < = 1, and 0 < = z < = 1; the preparation method of the material comprises the following steps: adding a vanadium source, a T source, a phosphorus source and a fluorine source in a stoichiometric ratio into a reaction kettle containing a reaction solvent, adding an ammonium source to keep the pH value to be 6-10, maintaining the temperature to be 120-250 DEG C, and reacting for 2-24 hours; naturally cooling, and washing with clear water to obtain a (NH4) xV < 1-y > TyPO4F < 1-z > Oz precursor; the preparation method comprises the following steps: fully grinding an excessive sodium source and a (NH4) xV < 1-y > TyPO4F < 1-z > Oz precursor, carrying out Na < + > / NH4 < + > molten salt exchange in a tubular furnace at 60-400 DEG C for 1-48 hours, introducing inert gas during reaction, and washing an obtained product with a washing solvent after the reaction is finished to remove the excessive sodium source; and drying in a drying oven at 50-250 DEG C for 1-30 hours to obtain the KTP type sodium-rich phosphate positive electrode material. By utilizing the induction effect of KTP configuration on V-O or T-O bonds, the voltage of V and T transition metal related redox couple is increased, and the energy density is improved.

Description

Technical Field

[0001] The invention relates to a KTP-type sodium-rich phosphate positive electrode material and a preparation method and application thereof, belonging to the field of preparation of positive electrode materials for sodium ion batteries. Background Art

[0002] In recent years, energy crises and environmental pollution have become increasingly prominent, driving the rapid development of clean energy sources such as solar, wind, and tidal power. However, the large-scale application of alternative energy sources has necessitated the critical development of energy storage technology. Rechargeable lithium-ion batteries, with their high energy density and conversion efficiency, have become a research hotspot in the energy storage field. However, limited lithium reserves and uneven geographical distribution pose challenges to their sustainable development. Against this backdrop, sodium-ion batteries, with their significant advantages such as abundant sodium reserves (2.64% in the Earth's crust) and low raw material costs, are rapidly developing as a key complementary technology to lithium-ion batteries in large-scale energy storage systems. In sodium-ion batteries, polyanionic phosphate cathode materials have attracted widespread attention due to their excellent structural stability, favorable safety profile, and three-dimensional ion diffusion capabilities. However, conventional phosphate cathode materials, such as sodium vanadium phosphate and sodium iron pyrophosphate, suffer from heavy molecular weight and low capacity, resulting in energy densities far lower than those of lithium iron phosphate materials used in lithium-ion batteries, limiting their practical application.

[0003] CN119812287A discloses a method for preparing an iron-based phosphate positive electrode material, wherein the chemical formula of the material is Na 3-4.5 Fe 2-3.5 (PO4) 2-2.5 P2O7. Although the reversible capacity of the material can be increased by regulating the elemental composition ratio, its heavy molecular weight limits its theoretical capacity to less than 130 mAh / g, and its actual capacity is only around 110 mAh / g, making its energy density far lower than that of lithium iron phosphate materials for lithium-ion batteries.

[0004] CN107394147B discloses a method for preparing a carbon-coated NaVPO4F cathode material with a tetragonal crystal structure. Despite its low molecular weight, the material achieves a reversible capacity of less than 120 mAh / g and an average voltage of only around 3.4 V, resulting in an energy density lower than that of lithium iron phosphate materials used in lithium-ion batteries.

[0005] KTiOPO4 (KTP) is a nonlinear optical crystal. The sodium-based phosphate cathode material with KTP structure has the general formula NaMPO4X (where Na replaces K; M replaces Ti and can be a variety of active transition metals such as V, Fe, Mn, Ni, Co, Mn, Cr, etc.; X replaces O and can be halogen elements, oxygen elements and OH - etc.), due to its special induction effect, it can significantly increase M n+ / Mn+1 In addition, by adjusting the composition ratio of X and M and the adjustment of chemical valence, KTP-type sodium-rich Na 1+a The MPO4X positive electrode (where a>1) realizes multi-electron reaction, increases reversible capacity, and ultimately improves the energy density of phosphate positive electrode materials, accelerating the practical application of sodium-based phosphate positive electrode materials.

[0006] This application is specifically proposed to address the problem of low energy density of the above-mentioned sodium ion battery phosphate positive electrode materials. Summary of the Invention

[0007] The purpose of the present invention is to solve the main problem of low energy density of the above-mentioned sodium ion battery phosphate positive electrode material.

[0008] The first object of the present invention is to provide a KTP type sodium-rich phosphate cathode material, the chemical formula of the phosphate cathode material is: Na x V 1-y T y PO4F 1-z O z , where 1<x≤2, 0<y≤1, 0≤z≤1.

[0009] Preferably, the T source in step S1 is a soluble salt, and the cation is Mn 2+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Co 3+ or Cr 3+ , anion is CH3COO - 、NO 3- 、SO4 2- or Cl - .

[0010] Using this technical solution, the present invention leverages the inductive effect of the KTP configuration on VO or TO bonds to increase the voltage of the V and T transition metal redox couples. Simultaneously, by adjusting the F / O ratio and introducing low-valent active T metal ions, a sodium-rich KTP-based sodium-rich phosphate cathode material is constructed, enabling multi-electron reactions and increasing reversible capacity. The entire process is short and simple to operate, making it suitable for large-scale production.

[0011] A second object of the present invention is to provide a method for preparing a KTP-type sodium-rich phosphate cathode material, comprising the following steps: S1: Preparation (NH4) x V 1-y T y PO4F 1-z O z Precursor Add vanadium source, T source, phosphorus source and fluorine source in a stoichiometric ratio into a reaction kettle containing a reaction solvent, add an ammonium source to maintain pH = 6-10, maintain the temperature at 120-250 ° C, and react for 2-24 hours; cool naturally and wash with clean water to obtain (NH4) x V 1-y T y PO4F 1-z O z Precursor; S2: Preparation of Na x V 1-y T y PO4F 1-z O z cathode materials Use excess sodium source with (NH4) x V 1-y T y PO4F 1-z O z After the precursor is fully ground, it is heated in a tube furnace at 60-400℃ for Na + / NH4 + The molten salt exchange is carried out for 1-48 hours, and an inert gas is introduced during the reaction. After the reaction is completed, the product is washed with a washing solvent to remove excess sodium source; then it is dried in an oven at 50-250°C for 1-30 hours to obtain a KTP-type sodium-rich phosphate positive electrode material.

[0012] Preferably, the vanadium source in step S1 has a concentration of 0.1-2 mol / L, including one or more of vanadyl sulfate, ammonium metavanadate, ammonium polyvanadate, vanadyl oxalate, vanadium chloride, vanadium trioxide, vanadium dioxide, vanadium pentoxide, vanadium acetylacetonate, and vanadyl acetylacetonate.

[0013] Preferably, the phosphorus source in step S1 is one or more of ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium monoammonium phosphate, sodium diammonium phosphate, sodium triammonium phosphate, potassium monoammonium phosphate, potassium diammonium phosphate, and potassium triammonium phosphate; the fluorine source is one or two of sodium ammonium fluoride and potassium ammonium fluoride; the ammonium source is ammonia water, monoammonium phosphate, diammonium phosphate, triammonium phosphate, ammonium fluoride, and NH4 + One or more buffer solutions.

[0014] Preferably, the sodium source in step S2 is one or more of sodium acetate, sodium oxalate, sodium formate, monosodium phosphate, disodium phosphate, trisodium phosphate, sodium nitrate, sodium glutamate, sodium alginate, and sodium citrate; and the inert gas is one or more of nitrogen, argon, nitrogen / hydrogen mixed gas, and argon / hydrogen mixed gas.

[0015] Preferably, the sodium source and (NH4) x V 1-y T yPO4F 1-z O z The molar ratio of the precursors is 1-10:1.

[0016] Preferably, the reaction solvent in step S1 is one or more of deionized water, ethanol, ethylene glycol, and acetone; and the washing solvent in step S2 is one or more of deionized water, ethanol, ethylene glycol, and acetone.

[0017] Preferably, the oven in step S2 is a forced air oven, a vacuum oven, a muffle furnace, a tube furnace or a microwave oven.

[0018] Using the above technical solution, button-type batteries assembled with the KTP-type sodium-rich phosphate cathode material obtained using the preparation method provided by the present invention were subjected to charge and discharge tests at 0.1 C. The battery demonstrated an initial discharge capacity exceeding 135 mAh / g, an average discharge voltage above 3.9 V, and an energy density exceeding 540 Wh / kg (calculated based on the active material content of the half-cell cathode material). The specific capacity at 10 C was above 100 mAh / g, and the capacity retention rate exceeded 80% after 2000 cycles at 10 C. This demonstrates the excellent electrochemical performance of this KTP-type sodium-rich phosphate cathode material.

[0019] The third object of the present invention is to provide a KTP-type sodium-rich phosphate cathode material for use in the battery field.

[0020] Beneficial effects of the present invention: (1) The present invention utilizes the inductive effect of the KTP configuration on the VO or TO bond to increase the voltage of the V and T transition metal-related redox couples and improve the energy density.

[0021] (2) The present invention adjusts the F / O composition ratio and introduces low-valent active T metal ions to adjust the material's crystal structure, electronic structure, and chemical bond strength, thereby constructing a sodium-rich KTP-type sodium-rich phosphate positive electrode material, achieving multi-electron reaction, increasing reversible capacity, and improving energy density.

[0022] (3) The KTP-type sodium-rich phosphate cathode material prepared by the present invention has the advantages of both high capacity and high voltage. Furthermore, the preparation method provided is simple to operate, has significant improvement effects, is easily industrialized, and is suitable for promotion and use in this field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the XRD pattern of the KTP-type sodium-rich phosphate positive electrode material prepared in Example 1 of the present invention.

[0024] Figure 2 A high-resolution transmission electron microscopy image (left) and the corresponding selected area electron diffraction pattern (right) of the KTP-type sodium-rich phosphate cathode material prepared in Example 1 of the present invention.

[0025] Figure 3 This is the charge-discharge curve of the KTP-type sodium-rich phosphate cathode material prepared in Example 1 of the present invention at 0.1C.

[0026] Figure 4 The cycling performance of the KTP-type sodium-rich phosphate cathode material prepared in Example 1 of the present invention at 10°C is shown. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0028] Example 1 S1: Preparation (NH4) 1.2 V 0.8 Mn 0.2 PO4F precursor Vanadium trioxide, manganese acetate, ammonium dihydrogen phosphate, and ammonium fluoride at a molar ratio of 0.4:0.2:1:1 were added to a reactor containing deionized water, and the concentration of the vanadium source was maintained at 0.8 mol / L. At the same time, an appropriate amount of ammonia water was added to maintain the pH value of the reaction at 6.5. The temperature was maintained at 180°C and the reaction was carried out for 12 hours. After natural cooling and washing, (NH4) was obtained. 1.2 V 0.8 Mn 0.2 PO4F precursor; S2: Preparation of Na 1.2 V 0.8 Mn 0.2 PO4F positive electrode material The obtained precursor was mixed evenly with sodium oxalate in a molar ratio of 1:2.5, and ion exchange was carried out at 300 ° C in a tube furnace for 24 h while argon was introduced as a protective gas. The reaction product was washed with a mixture of clean water and ethanol. Finally, the above product was dried in a blast oven at 120 ° C for 10 h to obtain the desired KTP-type sodium-rich Na 1.2 V 0.8 Mn 0.2 PO4F positive electrode material.

[0029] Example 2 S1: Preparation (NH4) 1.2 V 0.9 Fe 0.1 PO4O precursor Vanadyl sulfate, ferrous sulfate, ammonium phosphate, and ammonium fluoride were added to a reactor containing ethanol in a molar ratio of 0.9:0.1:1:0, maintaining the vanadium source concentration at 0.45 mol / L. Ammonia was added to maintain the pH at 7.5. The temperature was raised to 230°C and the reaction was continued for 24 hours. After cooling naturally, the resulting product was washed with ethanol to obtain (NH4) 1.2 V 0.9 Fe 0.1 PO4O precursor.

[0030] S2: Preparation of Na 1.2 V 0.9 Fe 0.1 PO4O cathode material The obtained precursor was mixed evenly with sodium acetate in a molar ratio of 1:5, and ion exchange was carried out in a tube furnace at 100 ° C for 48 h, while nitrogen was introduced as a protective gas, and the reaction product was washed with clean water; finally, the above product was dried in a muffle furnace at 80 ° C for 48 h to obtain the desired KTP-type sodium-rich Na 1.2 V 0.9 Fe 0.1 PO4O positive electrode material.

[0031] Example 3 S1: Preparation (NH4) 1.4 V 0.6 Mn 0.4 PO4F 0.5 O 0.5 Precursor Vanadium chloride, vanadyl sulfate, manganese sulfate, diammonium hydrogen phosphate, and ammonium fluoride were added to a reactor containing deionized water at a molar ratio of 0.3:0.3:0.4:1:0.5 to maintain a total vanadium source concentration of 1.2 mol / L -1 At the same time, add appropriate amount of ammonia water to maintain the pH value of the reaction at 7. Raise the temperature to 200℃ and react for 16 hours; after natural cooling, wash the obtained product with clean water to obtain (NH4) 1.4 V 0.6 Mn 0.4 PO4F 0.5 O 0.5 Precursor.

[0032] S2: Preparation of Na 1.4 V 0.6 Mn 0.4 PO4F 0.5 O 0.5 cathode materials The obtained precursor was mixed evenly with sodium glutamate in a molar ratio of 1:10, and ion exchange was carried out in a tube furnace at 200 ° C for 20 h, while hydrogen and argon mixed gas was introduced as a protective gas, and the reaction product was washed with clean water; finally, the above product was dried in a vacuum oven at 100 ° C for 12 h to obtain the desired KTP-type sodium-rich Na 1.4 V 0.6 Mn 0.4 PO4F 0.5 O 0.5 positive electrode material.

[0033] Example 4 S1: Preparation (NH4) 1.2 V 0.8 Cr 0.2 The molar ratio of PO4O is 0.8:0.2:1:0 of ​​vanadyl oxalate, chromium acetate, ammonium dihydrogen phosphate, and ammonium fluoride. The concentration of the vanadium source is maintained at 0.8 mol / L. At the same time, an appropriate amount of ammonia water is added to maintain the pH value of the reaction at 6.5. The temperature is raised to 250°C and the reaction is carried out for 5 hours. After natural cooling, the obtained product is washed with acetone to obtain (NH4) 1.2 V 0.8 Cr 0.2 PO4O precursor.

[0034] S2: Preparation of Na 1.2 V 0.8 Cr 0.2 PO4O cathode material The obtained precursor was mixed with sodium nitrate in a molar ratio of 1:7, and ion exchange was carried out in a tube furnace at 350℃ for 10 hours while argon was introduced as a protective gas. The reaction product was washed with clean water. Finally, the above product was dried in a tube furnace at 200℃ for 8 hours to obtain the desired KTP-type sodium-rich Na 1.2 V 0.8 Cr 0.2 PO4O positive electrode material.

[0035] Example 5 S1: Preparation (NH4) 1.2 V 0.8 Cu 0.1 Zn 0.1 PO4F precursor Vanadium trioxide, copper nitrate, zinc sulfate, ammonium dihydrogen phosphate, and ammonium fluoride at a molar ratio of 0.4:0.1:0.1:1:1 were added to a reactor containing deionized water, and the concentration of the vanadium source was maintained at 1.6 mol / L. An appropriate amount of ammonia water was added to maintain the pH value of the reaction at 6.0. The temperature was maintained at 200°C and the reaction was carried out for 10 hours. After natural cooling and washing, (NH4) was obtained. 1.2 V0.8 Cu 0.1 Zn 0.1 PO4F precursor; S2: Preparation of Na 1.2 V 0.8 Cu 0.1 Zn 0.1 PO4F positive electrode material The obtained precursor was mixed evenly with sodium alginate in a molar ratio of 1:1.5, and ion exchange was carried out at 250 ° C in a tube furnace for 22 h, while nitrogen was introduced as a protective gas, and the reaction product was washed with clean water; finally, the above product was dried in a muffle furnace at 130 ° C for 8 h to obtain the desired KTP-type sodium-rich Na 1.2 V 0.8 Cu 0.2 PO4F positive electrode material.

[0036] Example 6 S1: Preparation (NH4) 1.4 V 0.6 Ni 0.2 Mg 0.2 PO4F 0.5 O 0.5 Precursor Vanadium chloride, vanadyl sulfate, nickel sulfate, magnesium acetate, ammonium phosphate, and ammonium fluoride in a molar ratio of 0.3:0.3:0.2:0.2:1:0.5 were added to the reactor containing ethanol to maintain a total vanadium source concentration of 0.6 mol / L -1 At the same time, add an appropriate amount of buffer solution to maintain the pH value of the reaction at 7. Raise the temperature to 220℃ and react for 18 hours; after cooling naturally, wash the obtained product with clear ethanol to obtain (NH4) 1.4 V 0.6 Ni 0.2 Mg 0.2 PO4F 0.5 O 0.5 Precursor.

[0037] S2: Preparation of Na 1.4 V 0.6 Ni 0.2 Mg 0.2 PO4F 0.5 O 0.5 cathode materials The obtained precursor was mixed evenly with sodium glutamate in a molar ratio of 1:10, and ion exchange was carried out in a tube furnace at 200 ° C for 20 h, while hydrogen and argon mixed gas was introduced as a protective gas, and the reaction product was washed with clean water; finally, the above product was dried in a vacuum oven at 100 ° C for 12 h to obtain the desired KTP-type sodium-rich Na 1.4 V 0.6Ni 0.2 Mg 0.2 PO4F 0.5 O 0.5 positive electrode material.

[0038] Comparative Example 1 S1: Preparation of (NH4)VPO4F precursor Vanadium trioxide, ammonium dihydrogen phosphate, and ammonium fluoride at a molar ratio of 0.5:1:1 were added to a reactor containing deionized water to maintain the concentration of the vanadium source at 1 mol / L.

[0039] Other details are the same as in Example 1.

[0040] S2: Preparation of NaVPO4F positive electrode material Same as Example 1.

[0041] Comparative Example 2 S1: Preparation of (NH4)VPO4O precursor Vanadyl sulfate, ammonium phosphate, and ammonium fluoride at a molar ratio of 1:1:0 were added to a reactor containing ethanol to maintain the concentration of the vanadium source at 0.5 mol / L.

[0042] Other details are the same as in Example 1.

[0043] S2: Preparation of NaVPO4O positive electrode material Same as Example 1.

[0044] Test Example 1 Structural Analysis (1) X-ray analysis of the Na 1.2 V 0.8 Mn 0.2 PO4F cathode material was subjected to XRD analysis, and the test results were as follows Figure 1 As shown in the figure, it can be seen that the diffraction peaks of the prepared material correspond one to one with the standard spectrum, and the crystallinity is good, indicating that the obtained sodium-rich phosphate positive electrode material is a KTP structure.

[0045] (2) Using transmission electron microscopy, the Na prepared in Example 1 1.2 V 0.8 Mn 0.2 The microstructure of the PO4F cathode was analyzed, and the test results are as follows: Figure 2 As shown in the figure, it can be seen that the lattice fringes of the prepared material are clear, corresponding to the crystal plane index of the KTP structure.

[0046] Experimental Example 2 Electrochemical Performance Analysis 1. Battery preparation (1) Preparation of battery positive electrode sheets: The prepared KTP-type sodium-rich phosphate positive electrode material, Ketjen black, and polytetrafluoroethylene binder were ground and mixed in a mass ratio of 7:2:1, and then rolled thoroughly using a double-roller mill to form a film of uniform thickness. After drying in a vacuum drying oven at 120°C for 5 hours, the obtained positive electrode film was cut into square pieces with a side length of approximately 6 mm. After accurately weighing the square pieces, the mass of the active material in the positive electrode sheet was calculated based on the formula composition.

[0047] (2) Battery assembly: The above-obtained square positive electrode sheet, 16 mm diameter separator, 15 mm diameter sodium sheet, spring and gasket were assembled into a 2032-type testable button battery in a glove box (oxygen content less than 0.01 ppm, water content less than 0.01 ppm).

[0048] 2. Electrochemical performance test method: The assembled batteries were tested for charge and discharge at various rates using a blue battery test system. 1.2 V 0.8 Mn 0.2 The PO4F positive electrode was assembled into a button cell, with an initial discharge capacity of 140 mAh / g and a discharge voltage of 4.05 V ( Figure 3 ), the specific capacity at 10 C is 110 mAh / g, and after 2000 cycles, the capacity retention rate can reach 90% ( Figure 4 ). It can be seen that the prepared Na 1.2 V 0.8 Mn 0.2 PO4F cathode material has excellent electrochemical properties.

[0049] Meanwhile, referring to Table 1, by comparing Examples 1-4, it can be found that the KTP-type sodium-rich phosphate cathode materials obtained by the preparation method provided by the present invention all exhibit good electrochemical performance, with an initial discharge capacity of more than 135 mAh / g, a specific capacity of more than 100 mAh / g at 10 C, and a cycle retention rate of more than 80% after 2000 cycles. By comparing Example 1 with Comparative Example 1, it can be seen that by introducing low-valent Mn into NaVPO4F, 2+ The ion structure is sodium-rich (sodium content is greater than 1 mol per molecular formula), the reversible capacity of the material is significantly increased, and the cycle stability is enhanced; by comparing Example 2 and Comparative Example 2, it can be seen that the introduction of low-valent Fe into NaVPO4O 2+ The ionic structure is sodium-rich (sodium content is greater than 1 mol per molecular formula), the reversible capacity of the material is significantly increased, and the cycle stability is enhanced.

[0050] Table 1 Performance test results of each group

[0051] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0052] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A KTP-type sodium-rich phosphate cathode material, characterized in that: The chemical formula of the phosphate positive electrode material is: Na x V 1-y T y PO4F 1-z O z , where 1<x≤2, 0<y≤1, 0≤z≤1.

2. A KTP-type sodium-rich phosphate cathode material according to claim 1, characterized in that: T is Mn 2+ / Mn 3+ 、Fe 2 + / Fe 3+ 、Co 2+ / Co 3+ 、Ni 2+ / Ni 3+ Cr 3+ / Cr 4+ Mg 2+ 、Zn 2+ 、Cu 2+ One or more of the .

3. A method for preparing the KTP-type sodium-rich phosphate cathode material according to claim 1 or 2, characterized in that: The steps include: S1: Preparation (NH4) x V 1-y T y PO4F 1-z O z Precursor Add vanadium source, T source, phosphorus source and fluorine source in a stoichiometric ratio into a reaction kettle containing a reaction solvent, add an ammonium source to maintain pH = 6-10, maintain the temperature at 120-250 ° C, and react for 2-24 hours; cool naturally and wash with clean water to obtain (NH4) x V 1- y T y PO4F 1-z O z Precursor; S2: Preparation of Na x V 1-y T y PO4F 1-z O z cathode materials Use excess sodium source with (NH4) x V 1-y T y PO4F 1-z O z After the precursor is fully ground, it is heated in a tube furnace at 60-400℃ for Na + / NH4 + The molten salt exchange is carried out for 1-48 hours, and an inert gas is introduced during the reaction. After the reaction is completed, the product is washed with a washing solvent to remove excess sodium source; then it is dried in an oven at 50-250°C for 1-30 hours to obtain a KTP-type sodium-rich phosphate positive electrode material.

4. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3, wherein: The vanadium source in step S1 has a concentration of 0.1-2 mol / L, including one or more of vanadyl sulfate, ammonium metavanadate, ammonium polyvanadate, vanadyl oxalate, vanadium chloride, vanadium trioxide, vanadium dioxide, vanadium pentoxide, vanadium acetylacetonate, and vanadyl acetylacetonate.

5. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3, wherein: The T source in step S1 is a soluble salt, and the cation is Mn 2+ 、Ni 2+ 、Fe 2+ 、Fe 3+ 、Co 3+ or Cr 3+ , anion is CH3COO - 、NO 3- 、SO4 2- or Cl - .

6. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3, wherein: The phosphorus source in step S1 is one or more of ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium monoammonium phosphate, sodium diammonium phosphate, sodium triammonium phosphate, potassium monoammonium phosphate, potassium diammonium phosphate, and potassium triammonium phosphate; the fluorine source is one or two of sodium ammonium fluoride and potassium ammonium fluoride; the ammonium source is ammonia water, monoammonium phosphate, diammonium phosphate, triammonium phosphate, ammonium fluoride, and NH4 + One or more buffer solutions.

7. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3, wherein: The sodium source in step S2 is one or more of sodium acetate, sodium oxalate, sodium formate, monosodium phosphate, disodium phosphate, trisodium phosphate, sodium nitrate, sodium glutamate, sodium alginate, and sodium citrate; and the inert gas is one or more of nitrogen, argon, nitrogen / hydrogen mixed gas, and argon / hydrogen mixed gas.

8. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3 or 7, wherein: The sodium source and (NH4) x V 1-y T y PO4F 1-z O z The molar ratio of the precursors is 1-10:

1.

9. The method for preparing a KTP-type sodium-rich phosphate cathode material according to claim 3, wherein: The reaction solvent in step S1 is one or more of deionized water, ethanol, ethylene glycol, and acetone; the washing solvent in step S2 is one or more of deionized water, ethanol, ethylene glycol, and acetone.

10. Use of the KTP-type sodium-rich phosphate cathode material according to claim 1 or 2 in the field of batteries.

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