A method for synthesizing carbon-coated lithium iron pyrophosphate by hydrothermal method

Abstract

The invention discloses a method for synthesizing carbon-coated lithium ferrous pyrophosphate by a hydrothermal method. The method comprises the following steps of (1) weighing raw materials, dissolving a carbon source into distilled water or deionized water, and heating, stirring and dissolving in a water bath at the temperature of 50-90 DEG C; respectively dissolving a lithium source, an iron source and a phosphorus source into the deionized water, uniformly stirring the sources, sequentially adding the iron source and the lithium source into a solution dissolved with the carbon source, adding ammonia water to adjust the pH of the mixed solution to 4-6, adding the phosphorus source, heating the mixed solution in the water bath at the temperature of 50-90 DEG C, and stirring for 1-2 hours; (2) performing reaction on the mixed solution at 150-350 DEG C and the pressure of 1-10MPa for 3-10 hours, cooling to room temperature after the reaction is finished, and performing solid-liquid separation to obtain a solid which is a precursor solid-phase product; (3) drying the precursor solid-phase product, and then sintering to obtain the carbon-coated lithium ferrous pyrophosphate. The method has the advantage that the reaction temperature is relatively low, and the synthesis method is simple; the prepared carbon-coated lithium ferrous pyrophosphate serving as a positive electrode material is excellent in electrochemical performance.

Description

technical field

[0001] The invention belongs to the field of new energy materials, and relates to a method for synthesizing lithium iron pyrophosphate, a positive electrode active material of a lithium ion battery, in particular to a method for synthesizing carbon-coated lithium iron pyrophosphate by a hydrothermal method. Background technique

[0002] Since it was proposed in 1990, the commercialization of lithium-ion batteries has achieved great success, replacing traditional lead storage, nickel-hydrogen, and nickel-cadmium batteries, and occupying a dominant position in the field of portable electronic products. As people's needs continue to increase, lithium-ion batteries are expected to play a greater role in large-scale energy storage, electric vehicles and other fields.

[0003] Layered LiCoO 2 、LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 Materials are widely used in portable energy storage devices. However, when used as large-scale energy storage and power batteries, high cost ...

Examples

Embodiment 1

[0035] This embodiment includes the following steps:

[0036] (1) This example is designed to generate 0.01mol of the target product Li 2 FeP 2 o 7 , prepare 100ml of the solution; weigh 0.01mol of citric acid, add it into a beaker with 40ml of deionized water, put the beaker into a 50°C constant temperature water bath, and stir magnetically; weigh 0.005mol of ferric sulfate (Fe 2 (SO 4 ) 3 ) and 0.04mol of lithium hydroxide, measure 0.02mol of orthophosphoric acid, add them into three small beakers with 20ml of deionized water respectively, stir until they are all dissolved, add the solutions containing iron source and lithium source in turn into the solution with the carbon source dissolved, then add ammonia water to adjust the pH of the mixed solution to 6, and then add the solution containing the phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.1mol L -1 , magnetically stir the mixed solution in a water bath at 50°C for ...

Embodiment 2

[0043] This embodiment includes the following steps:

[0044] (1) This example is designed to generate 0.1mol of the target product Li 2 FeP 2 o 7 , prepare 1000ml of solution; weigh 0.1mol of ascorbic acid, add it into a beaker with 400ml of deionized water, put the beaker into a 60°C constant temperature water bath, and stir evenly with a mixer; weigh 0.1mol of ferric nitrate and 0.3mol of Lithium carbonate, measure 0.2mol of ammonium dihydrogen phosphate, add to three small beakers with 200ml of deionized water respectively, and stir until all of them are dissolved; Then add ammonia water to adjust the pH of the mixed solution to 5, then add the solution containing the phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.1mol L -1 , magnetically stir the mixed solution in a water bath at 80°C for 1 h;

[0045] (2) Pour the mixed solution into an integrated temperature-controlled stirring reactor. The volume of the reactor is 1...

Embodiment 3

[0049] This embodiment includes the following steps:

[0050] (1) This example is designed to generate 0.05mol of the target product Li 2 FeP 2 o 7 , prepare solution 1000ml; Weigh 0.06mol polyethylene glycol, add in the beaker that has 550ml deionized water, put the beaker in 60 ℃ constant temperature water bath, stir evenly with agitator; Iron and 0.25mol of lithium acetate, measure 0.11mol of ammonium dihydrogen phosphate, respectively add to three small beakers with 150ml of deionized water, and stir until they are completely dissolved; the solutions containing iron source and lithium source are sequentially Add to the solution with carbon source dissolved, then add ammonia water to adjust the pH of the mixed solution to 4, then add the solution with phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.05mol L -1 , magnetically stir the mixed solution in a water bath at 80°C for 2 hours;

[0051] (2) Pour the mixed solution i...

technical field

[0001] The invention belongs to the field of new energy materials, and relates to a method for synthesizing lithium iron pyrophosphate, a positive electrode active material of a lithium ion battery, in particular to a method for synthesizing carbon-coated lithium iron pyrophosphate by a hydrothermal method. Background technique

[0002] Since it was proposed in 1990, the commercialization of lithium-ion batteries has achieved great success, replacing traditional lead storage, nickel-hydrogen, and nickel-cadmium batteries, and occupying a dominant position in the field of portable electronic products. As people's needs continue to increase, lithium-ion batteries are expected to play a greater role in large-scale energy storage, electric vehicles and other fields.

[0003] Layered LiCoO 2 、LiNi 1 / 3 co 1 / 3 mn 1 / 3 o 2 Materials are widely used in portable energy storage devices. However, when used as large-scale energy storage and power batteries, high cost ...

Examples

Embodiment 1

[0035] This embodiment includes the following steps:

[0036] (1) This example is designed to generate 0.01mol of the target product Li 2 FeP 2 o 7 , prepare 100ml of the solution; weigh 0.01mol of citric acid, add it into a beaker with 40ml of deionized water, put the beaker into a 50°C constant temperature water bath, and stir magnetically; weigh 0.005mol of ferric sulfate (Fe 2 (SO 4 ) 3 ) and 0.04mol of lithium hydroxide, measure 0.02mol of orthophosphoric acid, add them into three small beakers with 20ml of deionized water respectively, stir until they are all dissolved, add the solutions containing iron source and lithium source in turn into the solution with the carbon source dissolved, then add ammonia water to adjust the pH of the mixed solution to 6, and then add the solution containing the phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.1mol L -1 , magnetically stir the mixed solution in a water bath at 50°C for ...

Embodiment 2

[0043] This embodiment includes the following steps:

[0044] (1) This example is designed to generate 0.1mol of the target product Li 2 FeP 2 o 7 , prepare 1000ml of solution; weigh 0.1mol of ascorbic acid, add it into a beaker with 400ml of deionized water, put the beaker into a 60°C constant temperature water bath, and stir evenly with a mixer; weigh 0.1mol of ferric nitrate and 0.3mol of Lithium carbonate, measure 0.2mol of ammonium dihydrogen phosphate, add to three small beakers with 200ml of deionized water respectively, and stir until all of them are dissolved; Then add ammonia water to adjust the pH of the mixed solution to 5, then add the solution containing the phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.1mol L -1 , magnetically stir the mixed solution in a water bath at 80°C for 1 h;

[0045] (2) Pour the mixed solution into an integrated temperature-controlled stirring reactor. The volume of the reactor is 1...

Embodiment 3

[0049] This embodiment includes the following steps:

[0050] (1) This example is designed to generate 0.05mol of the target product Li 2 FeP 2 o 7 , prepare solution 1000ml; Weigh 0.06mol polyethylene glycol, add in the beaker that has 550ml deionized water, put the beaker in 60 ℃ constant temperature water bath, stir evenly with agitator; Iron and 0.25mol of lithium acetate, measure 0.11mol of ammonium dihydrogen phosphate, respectively add to three small beakers with 150ml of deionized water, and stir until they are completely dissolved; the solutions containing iron source and lithium source are sequentially Add to the solution with carbon source dissolved, then add ammonia water to adjust the pH of the mixed solution to 4, then add the solution with phosphorus source to the mixed solution, then the iron ion concentration in the iron source is 0.05mol L -1 , magnetically stir the mixed solution in a water bath at 80°C for 2 hours;

[0051] (2) Pour the mixed solution i...

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