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Method for repairing waste lithium iron phosphate

A repair method, lithium iron phosphate technology, applied in chemical instruments and methods, phosphorus compounds, recycling of waste collectors, etc., can solve problems such as complex operation, uneven carbon distribution, low capacity, etc., to improve distribution uniformity, reduce Effect of powder resistivity and good cycle life

Pending Publication Date: 2022-04-01
天津赛德美新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the damage or even falling off of the carbon layer coated on the surface of the waste lithium iron phosphate, and the influence of the conductive carbon black mixed in the positive electrode during the recovery process, the carbon distribution in the waste lithium iron phosphate is not uniform, resulting in the repair of lithium iron phosphate in the prior art. higher resistivity and lower capacity
[0004] The invention patent with the publication number CN113582153A discloses a repaired and regenerated waste lithium iron phosphate positive electrode material and its repair and regeneration method. A carbon source is added to the waste lithium iron phosphate, and the carbon source is used as a reducing agent during the roasting process. On the one hand, the formation of amorphous carbon forms a layer of carbon layer in situ on the surface of lithium iron phosphate particles. Although it can supplement the carbon content, it still cannot overcome the shortcomings of uneven carbon distribution, and the obtained repaired lithium iron phosphate has a low capacity.
[0005] The invention patent with the publication number CN112174107A discloses a method for repairing and regenerating lithium iron phosphate positive electrode materials in waste batteries. After roasting waste and old lithium iron phosphate to remove carbon impurities, adding carbon sources, repairing by hydrothermal reaction, but this regeneration method cannot be used The original carbon in waste lithium iron phosphate has complex operation, long reaction time, low repair efficiency, high regeneration cost, and is not suitable for industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] The waste and old lithium iron phosphate restoration method in the present embodiment comprises the following steps:

[0035] (1) Add waste lithium iron phosphate and polyethylene glycol (PEG-200) with a viscosity of 22mPa·s and a boiling point of 250°C to the ribbon mixer at a mass ratio of 95:5, and mix evenly to obtain a mixture ;

[0036] (2) Send the mixture into the spray drying equipment for drying, set the inlet temperature to 220°C and the outlet temperature to 70°C to obtain solid particles;

[0037] (3) The solid particles were heated up to 750°C under the protection of nitrogen, and kept for 1 hour to obtain repaired lithium iron phosphate, and then the temperature was naturally lowered to 40°C, and taken out.

[0038] The powder resistivity of the repaired lithium iron phosphate is 29.6Ω.cm, the discharge specific capacity is 134.2mAh / g at 0.1C, and the discharge specific capacity is 131.9mAh / g after 100 cycles.

Embodiment 2

[0040] The waste and old lithium iron phosphate restoration method in the present embodiment comprises the following steps:

[0041](1) Premix the waste lithium iron phosphate, lithium carbonate and diammonium hydrogen phosphate, adjust the molar ratio of Li, Fe and P to 1.05:1:1, and then mix it with propylene glycol with a viscosity of 56mPa·s and a boiling point of 185°C , add in the ball mill according to the mass ratio of 80:20, mix evenly to obtain the mixture;

[0042] (2) Send the mixture into the spray drying equipment for drying, set the inlet temperature to 200°C, and the outlet temperature to 80°C to obtain solid particles;

[0043] (3) The solid particles were heated up to 730°C under the protection of argon, and kept for 3 hours to obtain repaired lithium iron phosphate, and then the temperature was naturally lowered to 40°C, and taken out.

[0044] The powder resistivity of the repaired lithium iron phosphate is 20.2Ω.cm, the discharge specific capacity at 0.1C...

Embodiment 3

[0046] The waste and old lithium iron phosphate restoration method in the present embodiment comprises the following steps:

[0047] (1) Premix waste lithium iron phosphate, lithium hydroxide and lithium dihydrogen phosphate, adjust the molar ratio of Li, Fe and P to 1.04:1:1, and then mix it with polypropylene glycol with a viscosity of 200mPa·s and a boiling point of 234 ° C, according to the mass ratio of 90:10 into the ball mill, mixed evenly, to obtain a mixture;

[0048] (2) Send the mixture into the spray drying equipment for drying, set the inlet temperature to 210°C, and the outlet temperature to 90°C to obtain solid particles;

[0049] (3) The solid particles were heated to 700°C under the protection of argon, and kept for 3 hours to obtain repaired lithium iron phosphate, and then the temperature was naturally lowered to 40°C, and taken out.

[0050] The powder resistivity of the repaired lithium iron phosphate is 19.6Ω.cm, the discharge specific capacity is 159.2m...

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Abstract

The invention provides a method for repairing waste lithium iron phosphate, which comprises the following steps: mixing waste lithium iron phosphate with dispersion liquid to obtain a mixture; carrying out spray drying on the mixture to obtain particles; and sintering the particles in an inert atmosphere to obtain the repaired lithium iron phosphate. According to the method for repairing the waste lithium iron phosphate, by adding the dispersion liquid with certain viscosity, the distribution uniformity of carbon in the waste lithium iron phosphate is improved, the powder resistivity of the repaired lithium iron phosphate is reduced, the capacity of repairing the lithium iron phosphate is improved, and by selecting the proper dispersion liquid, the dispersion effect of the carbon and the control of the carbon content are both considered, so that the repairing efficiency of the waste lithium iron phosphate is improved. And the repaired lithium iron phosphate has good cycle life.

Description

technical field [0001] The invention belongs to the technical field of lithium battery recycling, and in particular relates to a method for repairing waste lithium iron phosphate. Background technique [0002] Lithium-ion batteries used in new energy vehicles are about to usher in a climax of decommissioning. If they are not properly disposed of, they will cause environmental pollution and waste of resources. Therefore, the recycling and reuse of spent lithium-ion batteries has become a research hotspot. [0003] At present, the positive electrode materials in waste lithium-ion batteries mainly include lithium iron phosphate, lithium cobalt oxide and lithium nickel cobalt manganese oxide. Among them, the recovery technology of waste lithium iron phosphate includes high-temperature solid-phase method, hydrometallurgy and bioleaching method. High temperature solid phase method based on LiFePO 4 According to the attenuation mechanism of the battery and the charge and dischar...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M10/54
CPCY02W30/84
Inventor 赵小勇王维宙李花
Owner 天津赛德美新能源科技有限公司
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