Preparation method of high-performance aluminum and potassium co-doped sodium vanadium fluorophosphates/carbon composite material

Abstract

The invention discloses a preparation method of a high-performance aluminum and potassium co-doped sodium vanadium fluorophosphate / carbon composite material. According to the preparation method, a uniform solution is formed from a reaction raw material and low-molecular polyethylene glycol, a high-activity aluminum-doped vanadium phosphate / carbon composite material is prepared by combining carbonthermal reduction reaction, and the high-performance Na<1-x>K<x>V<1-y>Al<y>PO<4>F / C composite material is obtained by high-temperature reaction under inert atmosphere by taking the aluminum-doped vanadium phosphate / carbon composite material as the raw material. Carbon with high electron conductivity is generated from polyethylene glycol and a carbohydrate under a high-temperature inert atmospherecondition in an in-situ way, carbon can generate a reduction agent in carbon thermal reduction reaction, and growth and agglomeration of product particles also can be prevented; a larger passage is provided for sodium ion mobility by sodium doped with potassium, and the structural stability of sodium vanadium fluorophosphate is improved by vanadium doped with aluminum; and by combining the advantages of high electron conductivity, large sodium ion mobility passage and structural stability, the aluminum and potassium co-doped sodium vanadium fluorophosphates / carbon composite material has excellent electrochemical performance.

Description

technical field

[0001] The invention belongs to the technical field of energy materials, in particular to a method for preparing a high-performance aluminum-potassium co-doped sodium vanadium fluorophosphate / carbon composite material. Background technique

[0002] Sodium vanadium fluorophosphate (NaVPO) is a cathode material for sodium-ion batteries. 4 F) It has a stable open framework structure that allows reversible deintercalation / intercalation of all sodium ions with little structural change, its theoretical capacity is as high as 142.5mAh / g, and its operating voltage is as high as 3.7V. The above advantages make vanadium sodium fluorophosphate become one of the hot research materials for sodium ion batteries. However, the low electronic conductivity and ionic conductivity of sodium vanadium fluorophosphate seriously affect the electrochemical performance of sodium vanadium phosphate, resulting in its actual capacity being much smaller than its theoretical capacity, mak...

Examples

Embodiment example 1

[0018] Implementation Case 1: Weigh 0.01455mol of vanadium pentoxide, 0.03mol of ammonium dihydrogen phosphate, 0.0009mol of aluminum nitrate and 0.0075mol of sucrose, and transfer them all to a ball mill jar, and add about 20% polyethylene glycol by weight of the solid mixture (molecular weight is 200), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 180°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 2°C / min The heating rate is heated to 700°C, kept at a constant temperature for 8 hours, and cooled to room temperature with the furnace, then V 0.97 Al 0.03 PO 4 / C Composite. The prepared V 0.97 Al 0.03 PO 4 / C Mix all the materials with 0.0291mol sodium fluoride and 0.0009mol potassium fluoride evenly, then transfer the mixture to a tube furnace, and heat it to 700°C at a heating rate of 2°C / min under the protection of an argon atmosphere. 1h, cool to room temperature with the furna...

Embodiment example 2

[0020] Implementation case 2: Weigh 0.01425mol vanadium pentoxide, 0.03mol diammonium phosphate, 0.0015mol aluminum nitrate and 0.015mol glucose, and transfer to the ball mill jar, and add about 20% Polyethylene Glycol ( The molecular weight is 400), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 180°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 5°C / min Heating rate to 750°C, constant temperature for 6 hours, and cooling to room temperature with the furnace, then V 0.95 Al 0.05 PO 4 / C Composite. The prepared V 0.95 Al0.05 PO 4 / C All materials are mixed evenly with 0.0285mol sodium fluoride and 0.0015mol potassium fluoride, then the mixture is transferred to a tube furnace, and heated to 750°C at a heating rate of 5°C / min under the protection of an argon atmosphere. Constant temperature for 1h, then cool down to room temperature with the furnace, then Na 0.95 K 0.05 V 0.95 al ...

Embodiment example 3

[0022] Implementation Case 3: Weigh 0.0135mol vanadium pentoxide, 0.03mol diammonium hydrogen phosphate, 0.003mol aluminum nitrate and 0.015mol fructose, and transfer them all to a ball mill jar, and add about 10% polyethylene glycol by weight of the solid mixture (molecular weight is 600), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 160°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 5°C / min The heating rate is heated to 800°C, kept at a constant temperature for 4 hours, and cooled to room temperature with the furnace, then V 0.9 al 0.1 PO 4 / C Composite. The prepared V 0.9 al 0.1 PO 4 / C Mix all the materials with 0.0285mol sodium acetate, 0.0015mol potassium acetate, and 0.03mol ammonium fluoride, then transfer the mixture to a tube furnace, and heat it at a heating rate of 5°C / min under the protection of an argon atmosphere to 750°C, keep the temperature constant for 2 hours,...

technical field

[0001] The invention belongs to the technical field of energy materials, in particular to a method for preparing a high-performance aluminum-potassium co-doped sodium vanadium fluorophosphate / carbon composite material. Background technique

[0002] Sodium vanadium fluorophosphate (NaVPO) is a cathode material for sodium-ion batteries. 4 F) It has a stable open framework structure that allows reversible deintercalation / intercalation of all sodium ions with little structural change, its theoretical capacity is as high as 142.5mAh / g, and its operating voltage is as high as 3.7V. The above advantages make vanadium sodium fluorophosphate become one of the hot research materials for sodium ion batteries. However, the low electronic conductivity and ionic conductivity of sodium vanadium fluorophosphate seriously affect the electrochemical performance of sodium vanadium phosphate, resulting in its actual capacity being much smaller than its theoretical capacity, mak...

Examples

Embodiment example 1

[0018] Implementation Case 1: Weigh 0.01455mol of vanadium pentoxide, 0.03mol of ammonium dihydrogen phosphate, 0.0009mol of aluminum nitrate and 0.0075mol of sucrose, and transfer them all to a ball mill jar, and add about 20% polyethylene glycol by weight of the solid mixture (molecular weight is 200), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 180°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 2°C / min The heating rate is heated to 700°C, kept at a constant temperature for 8 hours, and cooled to room temperature with the furnace, then V 0.97 Al 0.03 PO 4 / C Composite. The prepared V 0.97 Al 0.03 PO 4 / C Mix all the materials with 0.0291mol sodium fluoride and 0.0009mol potassium fluoride evenly, then transfer the mixture to a tube furnace, and heat it to 700°C at a heating rate of 2°C / min under the protection of an argon atmosphere. 1h, cool to room temperature with the furna...

Embodiment example 2

[0020] Implementation case 2: Weigh 0.01425mol vanadium pentoxide, 0.03mol diammonium phosphate, 0.0015mol aluminum nitrate and 0.015mol glucose, and transfer to the ball mill jar, and add about 20% Polyethylene Glycol ( The molecular weight is 400), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 180°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 5°C / min Heating rate to 750°C, constant temperature for 6 hours, and cooling to room temperature with the furnace, then V 0.95 Al 0.05 PO 4 / C Composite. The prepared V 0.95 Al0.05 PO 4 / C All materials are mixed evenly with 0.0285mol sodium fluoride and 0.0015mol potassium fluoride, then the mixture is transferred to a tube furnace, and heated to 750°C at a heating rate of 5°C / min under the protection of an argon atmosphere. Constant temperature for 1h, then cool down to room temperature with the furnace, then Na 0.95 K 0.05 V 0.95 al ...

Embodiment example 3

[0022] Implementation Case 3: Weigh 0.0135mol vanadium pentoxide, 0.03mol diammonium hydrogen phosphate, 0.003mol aluminum nitrate and 0.015mol fructose, and transfer them all to a ball mill jar, and add about 10% polyethylene glycol by weight of the solid mixture (molecular weight is 600), start the ball mill, mix the mixture evenly, and dry the mixture in an oven at 160°C, transfer the dried mixture to a tube furnace, and under the protection of an argon atmosphere, heat at 5°C / min The heating rate is heated to 800°C, kept at a constant temperature for 4 hours, and cooled to room temperature with the furnace, then V 0.9 al 0.1 PO 4 / C Composite. The prepared V 0.9 al 0.1 PO 4 / C Mix all the materials with 0.0285mol sodium acetate, 0.0015mol potassium acetate, and 0.03mol ammonium fluoride, then transfer the mixture to a tube furnace, and heat it at a heating rate of 5°C / min under the protection of an argon atmosphere to 750°C, keep the temperature constant for 2 hours,...

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