Preparation method and application of a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material

Abstract

The application relates to a preparation method and application of a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material. The preparation method is as follows: a vanadium source, hydrogen peroxide and a solvent are uniformly mixed to obtain a mixed solution A; then, a sodium source, a phosphorus source and a fluorine source are added to obtain a mixed solution B; after the mixed solution B is transferred into a reaction kettle and high-temperature reaction, solid powder A is obtained through washing and drying, then, inert gas heating sintering is carried out, and the rich-pore nanospherical fluorophosphate of vanadium is obtained. The material has a rich-pore structure, can effectively shorten the electron and ion transmission path, the multi-pore structure can effectively buffer the volume change of the material in the charging and discharging process, guarantees the structural stability of the material, meanwhile, manganese doping further improves the intrinsic conductivity of the material, stabilizes the structure of the material, and improves the cycle performance of the material. Therefore, the material exhibits excellent long cycle performance as a sodium ion battery positive electrode.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of sodium-ion battery cathode materials, and particularly relates to a preparation method and application of a nano-spherical manganese-doped sodium vanadium fluorophosphate cathode material with rich pore. BACKGROUND

[0002] With the increasing demand for energy by mankind, it is inevitable to develop efficient electrochemical energy storage technology suitable for renewable energy. Among them, lithium ion batteries (LIBs) occupy the dominant position in the market with the advantages of low self-discharge rate, high energy density, etc. However, it is faced with the bottleneck of high cost and limited resource reserves. Therefore, sodium-ion batteries (SIBs) with high safety, abundant resources and low cost have once again attracted widespread attention.

[0003] Among various sodium battery cathode materials, the polyanion compound sodium vanadium fluorophosphate Na3V2(PO4)2F3 (NVPF) has a sodium superionic conductor (NASICON) type structure, which has good stability, fast ion transmission and high working potential, and is a promising cathode material. However, its intrinsic conductivity is low, and the rate performance of the material is not ideal. In addition, due to the large radius of sodium ions, the sodium ion diffusion coefficient is small, and the kinetic process is slow, which hinders the reversible deintercalation of sodium ions, and thus affects the cycle performance.

[0004] Nanometer structure and porous structure of sodium vanadium fluorophosphate material not only can accelerate the transmission of ions and electrons, but also show good strain adjustment ability in the ion deintercalation process, which is helpful to improve the service life of the material. The Chinese patent document with publication number CN118851137A discloses a sodium vanadium fluorophosphate composite material and its preparation method and application. The surface porous structure of the synthesized sodium vanadium fluorophosphate composite material increases the contact area of the electrolyte, and more fully infiltrates to help reduce the polarization degree during the redox reaction, thereby improving the capacity retention rate of the sodium vanadium fluorophosphate composite material. However, the particle size is relatively large, which leads to the deficiency of long cycle performance. The Chinese patent document with publication number CN118108204A discloses a preparation method of nano-ball-like sodium vanadium fluorophosphate electrode material. The nano-ball-like sodium vanadium fluorophosphate electrode material prepared has a solid structure and lacks pore structure, which leads to low transmission capacity of ions and electrons, and poor strain adjustment ability of the structure in the ion deintercalation process, resulting in insufficient electrochemical performance of the material. Therefore, the nanometer size sodium vanadium fluorophosphate material with porous structure is undoubtedly an effective measure to improve the electrochemical performance of the material. However, the synthesis method of many nanometer porous spherical materials needs complex steps, and the synthesis of nanometer porous spherical materials often needs to use expensive raw materials or reagents, such as some special metal salts. SUMMARY

[0005] The application aims to provide a preparation method of a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material.

[0006] In order to achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] In the first aspect, the application provides a preparation method of a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material, which specifically comprises the following steps:

[0008] (1) Vanadium source and hydrogen peroxide are added into a mixed solution of deionized water and an alcohol organic solvent, and are stirred and mixed uniformly to obtain a mixed solution A;

[0009] (2) A sodium source, a phosphorus source, a fluorine source and a manganese source are added into the mixed solution A and are stirred and mixed uniformly to obtain a mixed solution B; high-temperature reaction is performed to obtain a suspension, and centrifugation, washing and drying are performed to obtain a powder A;

[0010] (3) The powder A is sintered at high temperature under an inert atmosphere to obtain the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material.

[0011] Preferably, the concentration of the hydrogen peroxide is 30wt%, and the added amount is 1%-3% of the total volume of the deionized water and the alcohol organic solvent;

[0012] The volume ratio of the deionized water to the alcohol organic solvent is 1:0.5-1:3;

[0013] The alcohol organic solvent is one of polyethylene glycol or triethylene glycol, and the molecular weight of the polyethylene glycol is 200-600;

[0014] The vanadium source is one of vanadium pentoxide, ammonium metavanadate or sodium metavanadate;

[0015] The sodium source is one of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium metavanadate or sodium fluoride;

[0016] The phosphorus source is one of diammonium hydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate or sodium dihydrogen phosphate;

[0017] The fluorine source is one of sodium fluoride or ammonium fluoride;

[0018] The manganese source is one of manganese acetate, manganese nitrate or manganese sulfate;

[0019] The molar ratio of Na, V, P, F and Mn elements in the mixed solution B is 3-5:1.99:2:3-4:0.01.

[0020] Preferably, in the step (2), the high-temperature reaction temperature is 120-160℃, and the time is 6-24h.

[0021] Preferably, in step (3), the heating treatment condition: the high-temperature sintering temperature is 420-480℃, the time is 4-8h; the heating rate is 5℃ / min; the inert gas is selected from one of argon, nitrogen or helium.

[0022] In a second aspect, the present application provides a nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material with rich pores prepared by the above preparation method.

[0023] Preferably, the equivalent diameter of the nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material with rich pores is 80-180nm, and the equivalent diameter of the pores is 5-30nm.

[0024] In a third aspect, the present application also provides an application of the nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material with rich pores, which is used for a sodium ion battery positive electrode material.

[0025] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0026] 1) Under the action of the alcohol organic solvent, suitable reaction conditions of 120-160℃ and 6-24h are controlled. In this way, not only is the high solubility of the raw materials in the initial stage of the reaction ensured, but also the raw materials can be reacted, aggregated and precipitated to form nanocrystal nuclei, and then the nuclei slowly grow into nanospheres, without causing the nanocrystal nuclei to grow rapidly and agglomerate due to excessively high temperature or excessively long time, so that the particle size is increased. In addition, the alcohol organic solvent can also promote the uniform growth of the crystals and reduce the agglomeration of the particles, which is helpful to the formation of uniform nanospheres. In addition, the alcohol organic solvent can also provide a carbon source as a reducing agent to ensure the full reaction.

[0027] When hydrogen peroxide is heated to above 100℃, it will begin to decompose rapidly, producing water and oxygen, and releasing a large amount of heat. The generated gas not only helps to produce the pore structure of the material itself, but also helps to speed up the reaction, shorten the reaction time and reduce energy consumption.

[0028] The synergistic effect of suitable reaction conditions, hydrogen peroxide and alcohol organic solvent successfully obtains the nano-spherical structure with rich pores.

[0029] 2) The nanospheres with an equivalent diameter of 80-180 nm and rich pore structure can effectively increase the wetting area of electrolyte and material, greatly shorten the electron and ion transmission path during charging and discharging, and improve the ion migration rate. During the charging and discharging process of the battery, lithium ions and the like can quickly pass through these pores to transmit between the inside and outside of the electrode material, thereby improving the ion migration rate. The efficient material transmission characteristics enable the electrode material to fully exert its electrochemical performance, and even under the condition of large current charging and discharging, the supply and transmission of ions can be ensured, the electrode polarization phenomenon caused by poor ion transmission is avoided, and the cycle life of the battery is improved.

[0030] 3) The rich-pore nanospherical structure can effectively alleviate the volume expansion of the sodium vanadium fluorophosphate positive electrode material during the charging and discharging process, ensure the structural stability of the material during repeated charging and discharging, and effectively improve the cycle stability performance of the battery. The pore structure can also enhance the bonding force between the material and the current collector, further improve the structural stability of the electrode, and be beneficial to prolonging the cycle life of the battery.

[0031] 4) The rich-pore nanospherical structure is beneficial to the transmission of electrons. The skeleton part in the porous structure usually has good electrical conductivity, which can form a continuous electron conduction network. The good electrical conductivity can reduce the internal resistance of the electrode, reduce the energy loss during charging and discharging, and improve the overall performance of the battery.

[0032] 5) Manganese doping on the rich-pore nanospheres further improves the intrinsic conductivity of the material, stabilizes the structure of the material, and improves the cycle performance of the material. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 SEM image of the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material of Example 1;

[0034] Figure 2 TEM image of the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material of Example 1;

[0035] Figure 3 XRD image of the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material of Example 1;

[0036] Figure 4 TEM image of the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material of Example 2;

[0037] Figure 5 TEM image of the rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material of Example 3;

[0038] Figure 6 TEM image of the nanoscale sodium vanadium fluorophosphate positive electrode material prepared in Comparative Example 1;

[0039] Figure 7 TEM image of the sodium vanadium fluorophosphate positive electrode material prepared for Comparative Example 2;

[0040] Figure 8 Rate performance graph of the nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material rich in pores for Example 1;

[0041] Figure 9 Cycle performance graph of the nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material rich in pores for Example 1. DETAILED DESCRIPTION

[0042] The present application will be further described in conjunction with the accompanying drawings and specific examples, so that those skilled in the art can better understand the present application and implement it.

[0043] The scope of protection of the present application is not limited to this. Example 1

[0044] (1) 200 mL of deionized water and 400 mL of polyethylene glycol 200 were stirred and mixed uniformly, and then 9.95 mmol of vanadium pentoxide and 12 mL of 30 wt% hydrogen peroxide were added, and a uniform mixed solution A was obtained by stirring at 60°C for 1 h;

[0045] (2) 20 mmol of ammonium dihydrogen phosphate, 30 mmol of sodium fluoride and 0.1 mmol of manganese acetate were added to the above mixed solution A, and the mixed solution B was obtained by continuing to stir at 60°C for 1 h. The mixed solution B was added to a reaction kettle and reacted in an oven at 140°C for 12 h. After the reaction was completed, the reaction kettle was cooled to room temperature, centrifuged, washed 3 times, and then dried in a vacuum oven at 80°C for 12 h to obtain a solid powder A;

[0046] (3) The solid powder A was placed in a tube furnace, argon was introduced, and sintering was carried out at 450°C for 6 h at a heating rate of 5°C / min to obtain a nano-spherical manganese-doped sodium vanadium fluorophosphate positive electrode material rich in pores.

[0047] From Figure 1 and Figure 2 It can be seen that the synthesized sodium vanadium fluorophosphate material is a nanosphere with an equivalent diameter of 80-180 nm, and the dispersion is uniform. At the same time, the individual nanosphere is full of pores of different sizes, and the equivalent diameter of the pores is 5-30 nm. In addition, from the XRD pattern of Figure 3 It can be seen that the synthesized material has high crystallinity, and the peak position is consistent with the standard card, indicating that the phase structure of the synthesized sodium vanadium fluorophosphate is correct. From Figure 8 and Figure 9As can be seen, the obtained porous nanosphere manganese-doped sodium vanadium fluorophosphate cathode material exhibits a discharge capacity close to 90 mAh g⁻¹ even at a charge-discharge current density of 10 C. -1 And after 2000 cycles, the capacity retention rate was 82.9%. Example 2

[0048] (1) Take 200 mL of deionized water and 600 mL of polyethylene glycol 400 and stir to mix evenly. Then add 19.9 mmol of sodium metavanadate and 24 mL of 30 wt% hydrogen peroxide. Stir at 60 °C for 1 h to obtain a uniform mixed solution A.

[0049] (2) Take 20 mmol sodium dihydrogen phosphate, 40 mmol ammonium fluoride and 0.1 mmol manganese acetate and add them to the above mixed solution A. Stir at 60°C for 1 h to obtain a uniform mixed solution B. Add mixed solution B to the reaction vessel and react at 140°C in the oven for 12 h. After the reaction is completed, wait for the reaction vessel to cool to room temperature, centrifuge and wash 3 times, and then place it in the vacuum oven to dry at 80°C for 12 h to obtain solid powder A.

[0050] (3) Solid powder A was placed in a tube furnace, argon gas was introduced, and sintering was carried out at 450℃ for 6 hours with a heating rate of 5℃ / min to obtain a porous nanosphere manganese-doped sodium fluorophosphate cathode material.

[0051] Depend on Figure 4 The synthesized sodium vanadium fluorophosphate material appears to be nanospheres with uniform dispersion. Furthermore, each individual nanosphere is filled with pores of varying sizes. Example 3

[0052] (1) Take 400 mL of deionized water and 200 mL of polyethylene glycol 600 and stir to mix evenly. Then add 19.9 mmol of ammonium metavanadate and 6 mL of 30 wt% hydrogen peroxide. Stir at 60 °C for 1 h to obtain a uniform mixed solution A.

[0053] (2) Take 20 mmol sodium dihydrogen phosphate, 30 mmol ammonium fluoride and 0.1 mmol manganese acetate and add them to the above mixed solution A. Stir at 60°C for 1 h to obtain a uniform mixed solution B. Add mixed solution B to the reaction vessel and react at 140°C in the oven for 12 h. After the reaction is completed, wait for the reaction vessel to cool to room temperature, centrifuge, wash 3 times, and then place it in the vacuum oven to dry at 80°C for 12 h to obtain solid powder A.

[0054] (3) Solid powder A was placed in a tube furnace, argon gas was introduced, and sintering was carried out at 450℃ for 6 hours with a heating rate of 5℃ / min to obtain a porous nanosphere manganese-doped sodium fluorophosphate cathode material.

[0055] Depend onFigure 5 It can be seen that the synthesized sodium vanadium fluorophosphate material is nanospheres, and the dispersion is uniform. At the same time, the individual nanospheres are full of pores of different sizes, and the overall pore diameter is slightly larger. Example 4

[0056] (1) 200 mL of deionized water and 400 mL of polyethylene glycol 400 were stirred and mixed uniformly, then 19.9 mmol of ammonium metavanadate and 12 mL of 30wt% hydrogen peroxide were added, stirred at 60°C for 1h to obtain a uniform mixed solution A;

[0057] (2) 20 mmol of diammonium hydrogen phosphate, 35 mmol of sodium fluoride and 0.1 mmol of manganese nitrate were added to the above mixed solution A, and the stirring was continued at 60°C for 1h to obtain a uniform mixed solution B. The mixed solution B was added to the reaction kettle and reacted in the oven at 160°C for 6h. After the reaction was completed, the reaction kettle was cooled to room temperature, centrifuged, washed 3 times, and then placed in a vacuum oven at 80°C for 12h to obtain a solid powder A;

[0058] (3) The solid powder A was placed in a tube furnace, argon was introduced, and sintering was carried out at 480°C for 4h with a heating rate of 5°C / min to obtain a porous nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material. Example 5

[0059] (1) 300 mL of deionized water and 300 mL of polyethylene glycol 600 were stirred and mixed uniformly, then 19.9 mmol of ammonium metavanadate and 12 mL of 30wt% hydrogen peroxide were added, stirred at 60°C for 1h to obtain a uniform mixed solution A;

[0060] (2) 20 mmol of sodium dihydrogen phosphate, 30 mmol of sodium fluoride and 0.1 mmol of manganese sulfate were added to the above mixed solution A, and the stirring was continued at 60°C for 1h to obtain a uniform mixed solution B. The mixed solution B was added to the reaction kettle and reacted in the oven at 120°C for 24h. After the reaction was completed, the reaction kettle was cooled to room temperature, centrifuged, washed 3 times, and then placed in a vacuum oven at 80°C for 12h to obtain a solid powder A;

[0061] (3) The solid powder A was placed in a tube furnace, argon was introduced, and sintering was carried out at 420°C for 8h with a heating rate of 5°C / min to obtain a porous nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material. Example 6

[0062] (1) 200 mL of deionized water and 400 mL of triethylene glycol were stirred and mixed uniformly, then 19.9 mmol of ammonium metavanadate and 12 mL of 30wt% hydrogen peroxide were added, stirred at 60°C for 1h to obtain a uniform mixed solution A;

[0063] (2) Take 20 mmol of sodium dihydrogen phosphate, 30 mmol of sodium fluoride and 0.1 mmol of manganese acetate and add them to the above mixed solution A, continue to stir at 60°C for 1h to obtain a uniform mixed solution B, add the mixed solution B to the reaction kettle and react in the oven at 120°C for 12h, after the reaction is completed, wait for the reaction kettle to cool to room temperature, centrifuge, wash 3 times, and then place it in a vacuum oven at 80°C for 12h to obtain solid powder A;

[0064] (3) Place the solid powder A in a tube furnace, pass argon gas, sinter at 420°C for 6h with a heating rate of 5°C / min to obtain a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material. Comparative Example 1

[0065] The difference from Example 1 is that no hydrogen peroxide H2O2 is added in step (1).

[0066] (1) Take 200 mL of deionized water and 400 mL of polyethylene glycol 200 and stir them to mix uniformly, then add 9.95 mmol of vanadium pentoxide, and stir at 60°C for 1h to obtain a uniform mixed solution A;

[0067] (2) Take 20 mmol of ammonium dihydrogen phosphate, 30 mmol of sodium fluoride and 0.1 mmol of manganese acetate and add them to the above mixed solution A, continue to stir at 60°C for 1h to obtain a uniform mixed solution B, add the mixed solution B to the reaction kettle and react in the oven at 140°C for 12h, after the reaction is completed, wait for the reaction kettle to cool to room temperature, centrifuge, wash 3 times, and then place it in a vacuum oven at 80°C for 12h to obtain solid powder A;

[0068] (3) Place the solid powder A in a tube furnace, pass argon gas, sinter at 450°C for 6h with a heating rate of 5°C / min to obtain a manganese-doped sodium vanadium fluorophosphate positive electrode material.

[0069] From Figure 6 It can be seen that the manganese-doped sodium vanadium fluorophosphate positive electrode material obtained without adding hydrogen peroxide still presents a spherical shape, but its pores disappear, which shows that hydrogen peroxide plays a key role in the formation of the rich-pore structure. Comparative Example 2

[0070] The difference from Example 1 is that no alcohol organic solvent is added, i.e. all the alcohol organic solvent in step (1) is replaced by deionized water.

[0071] (1) Take 600 mL of deionized water, 9.95 mmol of vanadium pentoxide and 12 mL of 30wt% hydrogen peroxide and stir at 60°C for 1h to obtain a uniform mixed solution A;

[0072] (2) Take 20 mmol of ammonium dihydrogen phosphate, 30 mmol of sodium fluoride and 0.1 mmol of manganese acetate into the above mixed solution A, continue to stir at 60°C for 1h to obtain a uniform mixed solution B, add the mixed solution B into the reaction kettle and react in the oven at 140°C for 12h. After the reaction is completed, the reaction kettle is cooled to room temperature, centrifuged, washed 3 times, and then placed in a vacuum oven at 80°C for 12h to obtain solid powder A;

[0073] (3) Put the solid powder A into a tube furnace, pass argon, sinter at 450°C for 6h, and the heating rate is 5°C / min to obtain the Mn-doped sodium vanadium fluorophosphate positive electrode material.

[0074] By Figure 7 It can be seen that the Mn-doped sodium vanadium fluorophosphate positive electrode material obtained without adding an alcohol organic solvent has irregular particle morphology, different sizes, and the average size is significantly larger.

[0075] Battery assembly and test:

[0076] The prepared porous nanospherical sodium vanadium fluorophosphate positive electrode material is used as a positive active material, conductive carbon black Super P is used as a conductive agent, and polyvinylidene fluoride (PVDF) is used as a binder. The active material, Super P and PVDF are added into a mortar in a mass ratio of 7:2:1, and are ground for 30 min. Aluminum foil is used as a current collector to coat into a thin sheet, which is completely dried in a vacuum drying box, and then a positive electrode sheet is prepared by a slicer. The negative electrode is a metal sodium, the electrolyte is selected to be a NaClO4 (+FEC) solution, and a porous glass fiber membrane (GF / D) is used as a separator. The assembly of the button cell is carried out in an argon glove box with a water and oxygen value of less than 0.01 ppm.

[0077] Firstly, the positive electrode shell is placed flat on a glass plate, the positive electrode sheet is placed into the positive electrode shell with a pair of tweezers, and the positive electrode sheet is ensured to be centered. The electrolyte is sucked by a pipette and evenly coated on the positive electrode sheet, and attention should be paid to avoid contacting the separator to cover the positive electrode sheet and ensure not to contact the electrolyte. Then, the electrolyte is sucked by a pipette to wet the surface of the separator, ensure the flatness of the separator, clamp the sodium sheet in the center of the separator, and ensure the accurate position. Finally, the gasket is clamped on the sodium sheet to ensure alignment, the spring is clamped on the gasket to ensure alignment, the negative electrode shell is clamped with a pair of tweezers to cover the entire structure, and the assembly of the button cell is completed.

[0078] The assembled battery is tested for electrochemical performance using a new battery test system. The voltage window is set to 2.0-4.2 V, the charge and discharge current densities are selected to be 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C and 20C according to the specific capacity calculated theoretically and the mass of the corresponding positive electrode active material, and the electrochemical performance is tested. The results are as follows:

[0079]

[0080] By Figures 1 to 5 It can be seen that the materials synthesized in Examples 1 to 3 are nanometer-sized spherical structures, and each nanosphere has abundant vesicular structures. It can be seen from the above battery performance test comparison table that the nanosphere-like sodium vanadium fluorophosphate material with abundant vesicular pores obtained in Examples 1-6 as a positive electrode of a sodium ion battery has better initial capacity and cycle performance than Comparative Examples 1 and 2. This is because the nanometer-structured sodium vanadium fluorophosphate material and the abundant vesicular pore structure itself effectively increase the contact area of the material with the electrolyte, shorten the transmission path of electrons and ions in the charging and discharging process, and exhibit good strain adjustment capability in the ion deintercalation process, effectively improving the cycle life of the battery; in addition, the nanosphere-like material with abundant vesicular pores can effectively buffer the volume change of the material in the charging and discharging process, improving the structural stability of the material, thereby further effectively improving the material stability in the charging and discharging process; manganese doping further improves the intrinsic conductivity of the material, stabilizes the structure of the material, and improves the cycle performance of the material.

[0081] In comparison, in Comparative Example 1, since no hydrogen peroxide H2O2 is added, Figure 5 It can be seen that the material only presents a nanosphere-like structure and does not have an abundant vesicular pore structure. Therefore, the capacity retention rate after 10C cycling for 2000 cycles is 60.8%, which is lower than that of Example 1, which is 82.9%, which is mainly due to the lack of abundant vesicular pore structure, which cannot effectively buffer the volume change of the material in the charging and discharging process, resulting in poor structural stability of the material in the charging and discharging process; more obviously, the initial capacity of 98 mAh / g and the capacity retention rate of 43.4% of the material prepared in Comparative Example 2 are much lower than those of the nanosphere-like sodium vanadium fluorophosphate material prepared in Example 1, which is due to the lack of addition of an alcohol organic solvent, resulting in a micron-sized material with uneven particle size and irregular morphology. Even though the addition of hydrogen peroxide forms a certain amount of vesicular pore structure on the surface of the material, the electrochemical performance of the material is still poor (as shown in Figure 7 ).

[0082] The above describes the embodiments of the present application with reference to the accompanying drawings, but does not limit the protection scope of the present application. Any modification or similar substitution or supplement made by those skilled in the art to the described specific embodiments shall be within the protection scope of the present application.

Claims

1. A method for preparing a nano-spherical manganese-doped sodium vanadium fluorophosphate cathode material with rich pores; characterized in that, The method comprises the following steps: (1) adding a vanadium source and hydrogen peroxide into a mixed solution of deionized water and an alcohol organic solvent, and stirring to obtain a mixed solution A; (2) adding a sodium source, a phosphorus source, a fluorine source and a manganese source into the mixed solution A, and stirring to obtain a mixed solution B; high-temperature reaction is performed to obtain a suspension, and centrifugation, washing and drying are performed to obtain a powder A; (3) high-temperature sintering of the powder A under an inert atmosphere to obtain a rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material. The alcohol organic solvent is one of polyethylene glycol or tetraethylene glycol; the molecular weight of the polyethylene glycol is 200-600. In step (2), the high-temperature reaction temperature is 120-160 DEG C, and the time is 6-24 h.

2. The preparation method according to claim 1, characterized in that, The concentration of the hydrogen peroxide is 30 wt%, and the amount added is 1%-3% of the total volume of the deionized water and the alcohol organic solvent; The volume ratio of the deionized water to the alcohol organic solvent is 1:0.5-1:3; The vanadium source is one of vanadium pentoxide, ammonium metavanadate or sodium metavanadate; The sodium source is one of sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium metavanadate or sodium fluoride; The phosphorus source is one of diammonium hydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate or sodium dihydrogen phosphate; The fluorine source is one of sodium fluoride or ammonium fluoride; The manganese source is one of manganese acetate, manganese nitrate or manganese sulfate; The molar ratio of Na, V, P, F and Mn in the mixed solution B is 3-5:1.99:2:3-4:0.

01.

3. The production method according to claim 2, characterized by, In step (3), the high-temperature sintering temperature is 420-480 DEG C, the time is 4-8 h, the heating rate is 5 DEG C / min, and the inert gas is one of argon, nitrogen or helium.

4. A rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material prepared by the method according to any one of claims 1-3.

5. The rich-cavitated nanospherical manganese-doped sodium vanadium fluorophosphate cathode material of claim 4, wherein, The nanospheres of the positive electrode material have an equivalent diameter of 80-180 nm, and the pores have an equivalent diameter of 5-30 nm.

6. Use of the rich-cavitated nanosized manganese-doped sodium vanadium fluorophosphate cathode material according to any one of claims 4-5, characterized in that, The rich-pore nanospherical manganese-doped sodium vanadium fluorophosphate positive electrode material is used as a positive electrode material for a sodium ion battery.

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