Preparation method of lithium iron phosphate cathode material

Abstract

The invention discloses a preparation method of a lithium iron phosphate cathode material. The preparation method comprises the following steps of (1), dispersing iron phosphate into a dispersing agent, so as to obtain dispersion liquid A of the iron phosphate; (2), dispersing a lithium carbonate and magnesium chloride doping agent into a dispersing agent, so as to obtain lithium source-magnesium source doping agent dispersion liquid B; (3), slowly adding the dispersion liquid A of the iron phosphate into the lithium source-magnesium source doping agent dispersion liquid B, enabling an obtained first mixture to react to make a coarse material of a lithium iron phosphate material; (4), grinding and uniformly mixing the coarse material of the lithium iron phosphate material and carbon-source glucose in a dispersing medium ethanol, drying an obtained second mixture, sintering the second mixture for 12h to 24h at a temperature of 700 to 750 DEG C in a protective atmosphere of a nitrogen gas, and naturally cooling the second mixture to a room temperature, so as to obtain the lithium iron phosphate cathode material. The non-in-situ carbon coating is adopted by the preparation method; meanwhile, the carbon coating is carried out in a sintering process; the increment of a crystal particle of the lithium iron phosphate material in a long-time high-temperature sintering process is limited; the electronic conductivity and the ion diffusion rate of the material are further improved; the lithium iron phosphate cathode material has better rate charging and discharging performance.

Description

technical field

[0001] The invention relates to surface modification and modification of a lithium iron phosphate positive electrode material for a lithium ion battery, in particular to a preparation method of a lithium iron phosphate positive electrode material. Background technique

[0002] With the rapid development of the power battery and energy storage battery industry, people have put forward higher requirements for the service life and safety of lithium-ion batteries. Compared with other traditional positive electrode materials, lithium iron phosphate material has abundant raw materials, low price, green environmental protection, moderate working voltage, good thermal stability, especially lithium iron phosphate material has two remarkable characteristics of good cycle performance and high safety performance , so it has become the preferred cathode material for power and energy storage lithium-ion batteries, which has attracted widespread attention and research. [...

Examples

Embodiment 1

[0025] (1) Prepare the dispersion of iron phosphate: dissolve 17g of AEO-9 in 1L of ethanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0026] (2) Preparation of lithium source-magnesium source dopant dispersion: dissolve 17g of AEO-9 in 1L of ethanol under stirring, then add 8.4977mol of lithium carbonate, disperse at high speed for 28min, then add 8.887mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0027] (3) Add liquid B into the autoclave, then slowly add liquid A into liquid B, control the flow rate of liquid A to 88ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 178°C and react for 18 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, release the suspended matter, and filter with suction...

Embodiment 2

[0031] (1) Prepare the dispersion of iron phosphate: dissolve 7g of AEO-9 in 1L of methanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0032] (2) Preparation of lithium source-dopant magnesium source dispersion: dissolve 18g of AEO-9 in 1L of methanol under stirring, then add 8.499mol of lithium carbonate, disperse at high speed for 28min, then add 8.882mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0033] (3) Add liquid B to the autoclave, then slowly add liquid A to liquid B, control the flow rate of liquid A to 78ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 278°C and react for 6 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, release the suspended matter, and filter with suction to o...

Embodiment 3

[0037] (1) Prepare the dispersion of iron phosphate: dissolve 28g of AEO-9 in 1L of ethanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0038] (2) Preparation of lithium source-magnesium source dopant dispersion: dissolve 28g of AEO-9 in 1L of ethanol under stirring, then add 8.4977mol of lithium carbonate, disperse at high speed for 28min, then add 8.887mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0039] (3) Add liquid B into the autoclave, then slowly add liquid A into liquid B, control the flow rate of liquid A to 188ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 288°C and react for 12 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, discharge the suspended matter, and filter with suct...

technical field

[0001] The invention relates to surface modification and modification of a lithium iron phosphate positive electrode material for a lithium ion battery, in particular to a preparation method of a lithium iron phosphate positive electrode material. Background technique

[0002] With the rapid development of the power battery and energy storage battery industry, people have put forward higher requirements for the service life and safety of lithium-ion batteries. Compared with other traditional positive electrode materials, lithium iron phosphate material has abundant raw materials, low price, green environmental protection, moderate working voltage, good thermal stability, especially lithium iron phosphate material has two remarkable characteristics of good cycle performance and high safety performance , so it has become the preferred cathode material for power and energy storage lithium-ion batteries, which has attracted widespread attention and research. [...

Examples

Embodiment 1

[0025] (1) Prepare the dispersion of iron phosphate: dissolve 17g of AEO-9 in 1L of ethanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0026] (2) Preparation of lithium source-magnesium source dopant dispersion: dissolve 17g of AEO-9 in 1L of ethanol under stirring, then add 8.4977mol of lithium carbonate, disperse at high speed for 28min, then add 8.887mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0027] (3) Add liquid B into the autoclave, then slowly add liquid A into liquid B, control the flow rate of liquid A to 88ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 178°C and react for 18 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, release the suspended matter, and filter with suction...

Embodiment 2

[0031] (1) Prepare the dispersion of iron phosphate: dissolve 7g of AEO-9 in 1L of methanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0032] (2) Preparation of lithium source-dopant magnesium source dispersion: dissolve 18g of AEO-9 in 1L of methanol under stirring, then add 8.499mol of lithium carbonate, disperse at high speed for 28min, then add 8.882mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0033] (3) Add liquid B to the autoclave, then slowly add liquid A to liquid B, control the flow rate of liquid A to 78ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 278°C and react for 6 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, release the suspended matter, and filter with suction to o...

Embodiment 3

[0037] (1) Prepare the dispersion of iron phosphate: dissolve 28g of AEO-9 in 1L of ethanol under stirring, then add 1mol of iron phosphate, and disperse at high speed for 1h to obtain the dispersion of iron phosphate, denoted as A;

[0038] (2) Preparation of lithium source-magnesium source dopant dispersion: dissolve 28g of AEO-9 in 1L of ethanol under stirring, then add 8.4977mol of lithium carbonate, disperse at high speed for 28min, then add 8.887mol of magnesium chloride, and continue stirring 48min, obtain lithium source-magnesium source dopant dispersion liquid, denoted as B;

[0039] (3) Add liquid B into the autoclave, then slowly add liquid A into liquid B, control the flow rate of liquid A to 188ml / min, after adding liquid A, seal the autoclave, Under certain conditions, raise the temperature to 288°C and react for 12 hours. After the reaction is completed, cool down to room temperature, open the reaction kettle, discharge the suspended matter, and filter with suct...

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