Doped sodium vanadium phosphate and preparation method and application thereof

Abstract

A doped sodium vanadium phosphate and a preparation method and application thereof. Preparation steps of a nitrogen-doped peony-shaped molybdenum oxide in raw materials of the doped sodium vanadium phosphate are as follows: adding a regulator into a molybdenum-containing solution for reaction, concentrating and thermal treatment to obtain a peony-shaped molybdenum oxide; and dissolving the peony-shaped molybdenum oxide in a conditioning agent, and adding an amine source for standing, centrifuging, washing and heat treatment, thus obtaining the nitrogen-doped peony-shaped molybdenum oxide.

Claims

1. A preparation method of a nitrogen-doped peony-shaped molybdenum oxide, comprising the following steps of: (1) adding a regulator into a molybdenum-containing solution for reaction, concentrating and thermal treatment to obtain a peony-shaped molybdenum oxide; and (2) dissolving the peony-shaped molybdenum oxide in a conditioning agent, and adding an amine source for standing, centrifuging, washing and heat treatment, thus obtaining the nitrogen-doped peony-shaped molybdenum oxide; wherein, the regulator is at least one of nitric acid, ammonium nitrate, sodium persulfate, ammonium persulfate, concentrated sulfuric acid, H.sub.2O.sub.2, ozone or sodium hypochlorite; wherein in step (2), the conditioning agent is at least one of sodium acetate, ammonium acetate, sodium formate, diaminoethane, sodium oxalate, ammonium benzoate, sodium phenylacetate, sodium propionate, sodium tartrate, sodium citrate or ammonium citrate; and wherein in step (2), the amine source is at least one of aniline, dimethylamine, trimethylamine, benzylamine, phenethylamine, ethamine, diethylamine, propylamine, phenylene diamine, benzylamine, benzene dimethylamine or benzedrinum.

2. The preparation method according to claim 1, wherein in step (1), the molybdenum-containing solution is obtained by dissolving a molybdenum source in a solvent; and the molybdenum source is at least one of sodium molybdate, molybdenum acetate, molybdenum formate, molybdenum citrate, ammonium molybdate, molybdenum oxide or molybdenum powder.

3. The preparation method according to claim 1, wherein in step (2), a solid-liquid ratio of the peony-shaped molybdenum oxide to the conditioning agent and the amine source is (0.1 to 10):(50 to 200):(0.01 to 5) g/mL/g.

4. A nitrogen-doped peony-shaped molybdenum oxide prepared by the preparation method according to claim 1, wherein a chemical formula of the nitrogen-doped peony-shaped molybdenum oxide is NMoO.sub.3.

5. A preparation method of a doped sodium vanadium phosphate, comprising the following steps of: (1) mixing a vanadium source, a sodium source, a phosphorus source and the nitrogen-doped peony-shaped molybdenum oxide according to claim 4 for ball-milling, washing and concentrating to obtain a precursor; and (2) calcining the precursor to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.N-MoO.sub.3.

6. The preparation method according to claim 5, wherein in step (1), the vanadium source is at least one of metavanadic acid, sodium metavanadate, ammonium metavanadate, sodium orthovanadate or ammonium orthovanadate; and the sodium source is at least one of sodium hydroxide, sodium carbonate, sodium hydrogen phosphate, sodium dihydrogenphosphate, sodium oxalate, sodium formate, sodium citrate, sodium methanesulfonate and sodium acetate.

7. The preparation method according to claim 5, wherein in step (1), the phosphorus source is at least one of sodium phosphate, sodium hydrogen phosphate, ferrous phosphate, phosphoric acid, ammonium dihydrogen phosphate and diammonium phosphate; and a molar ratio of the sodium source to the vanadium source and the phosphorus source is (0.01 to 60):(0.01 to 40):(0.01 to 60).

8. A doped sodium vanadium phosphate prepared by the preparation method according to claim 5, wherein a chemical formula of the doped sodium vanadium phosphate is Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.mN-MoO.sub.3, and 0.0001?m?0.1.

9. A battery, comprising the doped sodium vanadium phosphate according to claim 8.

10. A nitrogen-doped peony-shaped molybdenum oxide prepared by the preparation method according to claim 2, wherein a chemical formula of the nitrogen-doped peony-shaped molybdenum oxide is NMoO.sub.3.

11. A nitrogen-doped peony-shaped molybdenum oxide prepared by the preparation method according to claim 3, wherein a chemical formula of the nitrogen-doped peony-shaped molybdenum oxide is NMoO.sub.3.

12. A doped sodium vanadium phosphate prepared by the preparation method according to claim 6, wherein a chemical formula of the doped sodium vanadium phosphate is Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.mN-MoO.sub.3, and 0.0001?m?0.1.

13. A doped sodium vanadium phosphate prepared by the preparation method according to claim 7, wherein a chemical formula of the doped sodium vanadium phosphate is Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.mN-MoO.sub.3, and 0.0001?m?0.1.

14. A preparation method of a doped sodium vanadium phosphate, comprising the following steps of: (1) mixing a vanadium source, a sodium source, a phosphorus source and the nitrogen-doped peony-shaped molybdenum oxide according to claim 10 for ball-milling, washing and concentrating to obtain a precursor; and (2) calcining the precursor to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.N-MoO.sub.3.

15. A preparation method of a doped sodium vanadium phosphate, comprising the following steps of: (1) mixing a vanadium source, a sodium source, a phosphorus source and the nitrogen-doped peony-shaped molybdenum oxide according to claim 11 for ball-milling, washing and concentrating to obtain a precursor; and (2) calcining the precursor to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.N-MoO.sub.3.

16. A battery, comprising the doped sodium vanadium phosphate according to claim 12.

17. A battery, comprising the doped sodium vanadium phosphate according to claim 13.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a process flowchart of Embodiment 1 of the present disclosure;

(2) FIG. 2 is an SEM graph of a peony-shaped molybdenum oxide in Embodiment 3;

(3) FIG. 3 is an SEM graph of a sodium vanadium phosphate in Embodiment 3; and

(4) FIG. 4 is an SEM graph of a sodium vanadium phosphate in Comparative Example 1.

DETAILED DESCRIPTION

(5) The concepts and the technical effects produced of the present disclosure will be clearly and completely described in conjunction with the embodiments so as to sufficiently understand the objects, the features and the effects of the present disclosure. Obviously, the described embodiments are merely some embodiments of the disclosure, rather than all the embodiments. Other embodiments obtained by those skilled in the art without going through any creative effort shall all fall within the protection scope of the disclosure.

Embodiment 1

(6) A preparation method of a doped sodium vanadium phosphate of this embodiment included the following steps of: (1) peony-shaped three-dimensional molybdenum oxide: dissolving 60 g of molybdenum acetate in 400 mL of acetone, adding 25 mL of H.sub.2O.sub.2 with a mass fraction of 28% for reaction, removing gases in the reaction, evaporating and dehydrating the reacted solution, then heating the solution at 460? C. for 6 hours, cooling, washing and drying to obtain 21 g of peony-shaped molybdenum oxide; (2) nitrogen-doped peony-shaped molybdenum oxide (nitrogen-doped peony-shaped three-dimensional molybdenum oxide): adding 8.3 g of peony-shaped molybdenum oxide to 100 mL of 0.012 mol/L ammonium acetate solution (a pH of ammonium acetate=7.8), adding 1.5 mL of benzylamine, then standing, centrifuging, washing and drying the mixture, sending the mixture to an Ar atmosphere heating furnace for high-temperature treatment at 440? C. for 10 hours, and then cooling, washing and drying to obtain 8.4 g of nitrogen-doped peony-shaped molybdenum oxide; (3) synthesis: mixing 23.5 g of ammonium metavanadate, 12 g of sodium hydroxide, 300 mL of 11.5 wt % phosphoric acid and 20 mL of methanol, and then adding 1.2 g of nitrogen-doped peony-shaped molybdenum oxide (an addition amount of the nitrogen-doped peony-shaped molybdenum oxide was 1.7% of a total mass of the ammonium metavanadate, the sodium hydroxide and the phosphoric acid) to obtain a mixture, ball-milling the mixture at 840 r/min in Ar atmosphere (a discharge particle size was less than 50 m) for 8 hours, washing and drying the mixture to remove methanol, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (4) sending the precursor into a heating furnace, introducing Ar, calcining at 550? C. for 8 hours, and then cooling to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.0.017NMoO.sub.3.

Embodiment 2

(7) A preparation method of a doped sodium vanadium phosphate of this embodiment included the following steps of: (1) peony-shaped three-dimensional molybdenum oxide: dissolving 60 g of molybdenum acetate in 400 mL of acetone, adding 25 mL of H.sub.2O.sub.2 with a mass fraction of 28% for reaction, removing gases in the reaction, evaporating and dehydrating the reacted solution, then heating the solution at 460? C. for 6 hours, cooling, washing and drying to obtain 21 g of peony-shaped molybdenum oxide; (2) nitrogen-doped peony-shaped molybdenum oxide (nitrogen-doped peony-shaped three-dimensional molybdenum oxide): adding 10 g of peony-shaped molybdenum oxide to 120 mL of 0.012 mol/L ammonium acetate solution (a pH of ammonium acetate=7.8), adding 1.5 mL of benzylamine, then standing, centrifuging, washing and drying the mixture, sending the mixture to an Ar atmosphere heating furnace for high-temperature treatment at 485? C. for 10 hours, and then cooling, washing and drying to obtain 10.3 g of nitrogen-doped peony-shaped molybdenum oxide; (3) synthesis: mixing 23.5 g of ammonium metavanadate, 12 g of sodium hydroxide, 300 mL of 11.5 wt % phosphoric acid and 25 mL of methanol, and then adding 1.8 g of nitrogen-doped peony-shaped molybdenum oxide (an addition amount of the nitrogen-doped peony-shaped molybdenum oxide was 2.6% of a total mass of the ammonium metavanadate, the sodium hydroxide and the phosphoric acid) to obtain a mixture, ball-milling the mixture at 900 r/min in Ar atmosphere for 8 hours (a discharge particle size was less than 50 m), washing and drying the mixture to remove methanol, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (4) sending the precursor into a heating furnace, introducing Ar, calcining at 550? C. for 8 hours, and then cooling to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.0.026NMoO.sub.3.

Embodiment 3

(8) A preparation method of a doped sodium vanadium phosphate of this embodiment included the following steps of: (1) peony-shaped three-dimensional molybdenum oxide: dissolving 25 g of molybdenum acetate in 240 mL of propanetriol, adding 18 mL of H.sub.2O.sub.2 with a mass fraction of 28% for reaction, removing gases in the reaction, evaporating and dehydrating the reacted solution, then heating the solution at 530? C. for 8 hours, cooling, washing and drying to obtain 25 g of peony-shaped molybdenum oxide; (2) nitrogen-doped peony-shaped molybdenum oxide (nitrogen-doped peony-shaped three-dimensional molybdenum oxide): adding 10 g of peony-shaped molybdenum oxide to 100 mL of 0.034 mol/L sodium citrate solution (a pH of the sodium citrate solution was regulated to be 8.1), adding 1.5 mL of benzylamine, then standing, centrifuging, washing and drying the mixture, sending the mixture to an Ar atmosphere heating furnace for high-temperature treatment at 440? C. for 10 hours, and then cooling, washing and drying to obtain 10.3 g of nitrogen-doped peony-shaped molybdenum oxide; (3) synthesis: mixing 23.5 g of ammonium metavanadate, 20.4 g of sodium formate, 35 g of ammonium dihydrogen phosphate and 20 mL of triethanolamine, and then adding 1.7 g of nitrogen-doped peony-shaped molybdenum oxide (an addition amount of the nitrogen-doped peony-shaped molybdenum oxide was 2.2% of a total mass of the ammonium metavanadate, the sodium formate and the ammonium dihydrogen phosphate) to obtain a mixture, ball-milling the mixture at 840 r/min in Ar atmosphere for 10 hours (a discharge particle size was less than 50 m), washing and drying the mixture to remove triethanolamine, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (4) sending the precursor into a heating furnace, introducing Ar, calcining at 660? C. for 8 hours, and then cooling to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.0.022NMoO.sub.3.

Embodiment 4

(9) A preparation method of a doped sodium vanadium phosphate of this embodiment included the following steps of: (1) peony-shaped three-dimensional molybdenum oxide: dissolving 25 g of molybdenum acetate in 240 mL of propanetriol, adding 20 mL of H.sub.2O.sub.2 with a mass fraction of 28% for reaction, removing gases in the reaction, evaporating and dehydrating the reacted solution, then heating the solution at 530? C. for 8 hours, cooling, washing and drying to obtain 25 g of peony-shaped molybdenum oxide; (2) nitrogen-doped peony-shaped molybdenum oxide (nitrogen-doped peony-shaped three-dimensional molybdenum oxide): adding 8.3 g of peony-shaped molybdenum oxide to 100 mL of 0.034 mol/L sodium citrate solution (a pH of the sodium citrate solution was regulated to be 8.1), adding 1.5 mL of benzylamine, then standing, centrifuging, washing and drying the mixture, sending the mixture to an Ar atmosphere heating furnace for high-temperature treatment at 440? C. for 10 hours, and then cooling, washing and drying to obtain 8.8 g of nitrogen-doped peony-shaped molybdenum oxide; (3) synthesis: mixing 35 g of ammonium metavanadate, 20.4 g of sodium formate, 35 g of ammonium dihydrogen phosphate and 25 mL of triethanolamine, and then adding 2.0 g of nitrogen-doped peony-shaped molybdenum oxide (an addition amount of the nitrogen-doped peony-shaped molybdenum oxide was 2.5% of a total mass of the ammonium metavanadate, the sodium formate and the ammonium dihydrogen phosphate) to obtain a mixture, ball-milling the mixture at 720 r/min in Ar atmosphere for 12 hours (a discharge particle size was less than 50 m), washing and drying the mixture to remove triethanolamine, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (4) sending the precursor into a heating furnace, introducing Ar, calcining at 660? C. for 8 hours, and then cooling to obtain the doped sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.Math.0.025NMoO.sub.3.

Comparative Example 1

(10) A preparation method of a sodium vanadium phosphate of this comparative example included the following steps of: (1) synthesis: mixing 23.5 g of ammonium metavanadate, 12 g of sodium hydroxide, 300 mL of 11.5 wt % phosphoric acid and 9 mL of methanol, and ball-milling the mixture at 840 r/min in Ar atmosphere for 8 hours (a discharge particle size was less than 50 m), washing and drying the mixture to remove methanol, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (2) sending the precursor into a heating furnace, introducing Ar, calcining at 550? C. for 8 hours, and then cooling to obtain the sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.

Comparative Example 2

(11) A preparation method of a doped sodium vanadium phosphate of this comparative example included the following steps of: (1) synthesis: mixing 35 g of ammonium metavanadate, 20.4 g of sodium formate, 35 g of ammonium dihydrogen phosphate and 25 mL of triethanolamine, and ball-milling the mixture at 840 r/min in Ar atmosphere for 8 hours (a discharge particle size was less than 50 m), washing and drying the mixture to remove the 25 mL of triethanolamine, and then evaporating and drying the mixture to obtain a Na.sub.3V.sub.2(PO.sub.4).sub.3 precursor; and (2) sending the precursor into a heating furnace, introducing Ar, calcining at 660? C. for 8 hours, and then cooling to obtain the sodium vanadate phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3.

(12) Analysis of Embodiments 1 to 4 and Comparative Examples 1 to 2:

(13) The doped sodium vanadium phosphates or the sodium vanadate phosphates obtained in Embodiments 1 to 4 and Comparative Examples 1 to 2, acetylene black and PVDF were dissolved in deionized water at a mass ratio of 90:5:5 and stirred into slurry, and then the slurry was evenly coated on aluminum foil by a coater, dried and made into positive plates with 1.1 mol/L sodium hexafluorophosphate, DMC/EMC/PC solvents and other additives as electrolytes, and graphite as anodes to prepare coin cells. A BTS battery tester was used to test the cycle performances of the cells, wherein a test voltage ranged from 3.0 V to 4.2 V, a current density was 25 mAh.Math.g.sup.?1, and a FBT-9A one-point method was used to test BET values.

(14) TABLE-US-00001 TABLE 1 Data of Embodiments 1 to 4 and Comparative Examples 1 to 2: Specific capacity Coulombic efficiency (mA .Math. h g.sup.?1)/cycles (%)/cycles BET Sample 1 20 50 100 1 20 50 100 (m.sup.2/g) Embodiment 1 138.8 134.9 117.5 104.6 91.5 88.1 83.4 77.3 1.38 Embodiment 2 146.9 132.6 120.2 105.0 91.0 87.9 79.6 75.4 1.20 Embodiment 3 154.3 153.6 121.3 107.8 92.8 86.5 81.3 75.9 1.65 Embodiment 4 151.0 146.1 122.8 108. 92.3 88.3 80.4 76.1 1.31 Comparative Example 1 90.3 86.8 73.5 58.6 74.5 70.7 71.9 56.3 0.77 Comparative Example 2 95.6 88.3 78.2 57.5 76.2 73.8 68.4 54.4 0.92

(15) It can be seen from Table 1 that, compared with Comparative Examples 1 to 2, the decrease of the capacity retention rates of Embodiments 1 to 4 at the 1.sup.st, 20.sup.th, 50.sup.th and hundredth discharge times are not obvious, the Coulomb efficiencies are all high, and the BET values of Embodiments 1 to 4 are 1.38 m.sup.2/g, 1.20 m.sup.2/g, 1.65 m.sup.2/g and 1.31 m.sup.2/g respectively. The BET values of Comparative Examples 1-2 are 0.77 and 0.92 respectively, and the BET values of Comparative Examples are lower.

(16) FIG. 1 is a process flowchart of Embodiment 1: adding molybdenum acetate into acetone, adding H.sub.2O.sub.2 for reaction, removing gases in the reaction, evaporating and dehydrating the solution after the reaction, then heating, cooling, washing and drying to obtain a peony-shaped molybdenum oxide, adding the peony-shaped molybdenum oxide into an ammonium acetate solution, adding benzylamine for standing, centrifuging, washing and drying, after high-temperature treatment, cooling, washing and drying to obtain a nitrogen-doped peony-shaped molybdenum oxide; mixing ammonium metavanadate, sodium hydroxide, phosphoric acid and methanol, then adding the nitrogen-doped peony-shaped molybdenum oxide for grinding, washing and drying to obtain a mixture, sending the mixture to a heating furnace, calcining and cooling to obtain a doped sodium vanadium phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3/NMoO.sub.3.

(17) FIG. 2 is the peony-shaped molybdenum oxide prepared in step (1) of Embodiment 3, with a size of about 48 m.

(18) FIG. 3 is the doped sodium vanadium phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3/NMoO.sub.3 prepared in step (4) of Embodiment 3, and most of the peony-like molybdenum oxides are 40 m to 60 m in size.

(19) FIG. 4 is the granular sodium vanadium phosphate Na.sub.3V.sub.2(PO.sub.4).sub.3 prepared in step (2) of the comparative example, with a size of about 2 m.

(20) The embodiments of the present disclosure are described in detail with reference to the drawings above, but the present disclosure is not limited to the above embodiments, and various changes may also be made within the knowledge scope of those of ordinary skills in the art without departing from the purpose of the present disclosure. In addition, in case of no conflict, the embodiments in the application and the features in the embodiments may be combined with each other.