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Purification method of lithium difluorophosphate

A technology of lithium difluorophosphate and purification method, applied in the field of purification of lithium difluorophosphate, can solve the problems of battery damage, inability to play a lifting role, and inability to form a passivation layer on the surface of graphite electrodes.

Inactive Publication Date: 2019-12-13
ZHUHAI SMOOTHWAY ELECTRONICS MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The high concentration of metal impurity ions may also lead to the inability to form an effective passivation layer on the surface of the graphite electrode, causing the entire battery to be damaged
[0007] In summary, lithium difluorophosphate as an additive can significantly improve the electrochemical performance of the battery, but low-quality lithium 2 The introduction of 0 and metal impurity ions leads to battery performance failure

Method used

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  • Purification method of lithium difluorophosphate
  • Purification method of lithium difluorophosphate
  • Purification method of lithium difluorophosphate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Replace the stirring tank with weighing with nitrogen until the water content is less than 15ppm, press in 100kg of ethylene glycol dimethyl ether solvent, add 25kg of lithium difluorophosphate to be purified, stir and dissolve at room temperature for 2 hours.

[0025] Start the diaphragm pump to pass the dissolved lithium difluorophosphate solution through the 4A lithiated molecular sieve tower and 5A lithiated molecular sieve tower at 30-50L / min, and return to the stirring tank after passing through the 0.1um precision filter, and circulate and dehydrate for 2 hours.

[0026] Add 65mL of hexamethyldisilazane dropwise to the stirred tank, raise the temperature to 40°C, stir for 0.5h, continue to heat up to 65°C, turn on the vacuum pump to maintain a vacuum of -0.8bar, concentrate in vacuo until the displayed weight of the stirred tank is 40kg, stop heating, Naturally lower the temperature to 40°C, turn on the circulating refrigerant and continue to cool down to 10°C, an...

Embodiment 2

[0032] Replace the stirred tank with weighing with nitrogen until the water content is less than 15ppm, press into 120kg of acetonitrile solvent, add 25kg of lithium difluorophosphate to be purified, stir and dissolve at room temperature for 2.5h.

[0033] Start the diaphragm pump to pass the dissolved lithium difluorophosphate solution through the 4A lithiated molecular sieve tower and 5A lithiated molecular sieve tower at 30-50L / min, and return to the stirring tank after passing through the 0.1um precision filter for 3 hours of circular dehydration. Add 65mL of dicyclohexylcarbodiimide dropwise to the stirred tank, raise the temperature to 40°C, stir for 0.5h, continue to raise the temperature to 65°C, turn on the vacuum pump to maintain a vacuum degree of -0.8bar, concentrate in vacuo until the displayed weight of the stirred tank is 40kg, stop heating, Naturally lower the temperature to 40°C, turn on the circulating refrigerant and continue to cool down to 0°C, and keep war...

Embodiment 3

[0039] Replace the stirring tank with weighing with nitrogen until the water content is less than 15ppm, press into 100kg of ethylene glycol methyl ether solvent, add 25kg of lithium difluorophosphate to be purified, stir and dissolve at room temperature for 2.5h.

[0040] Start the diaphragm pump to pass the dissolved lithium difluorophosphate solution through the 4A lithiated molecular sieve tower and 5A lithiated molecular sieve tower at 30-50L / min, and return to the stirring tank after passing through the 0.1um precision filter, and circulate and dehydrate for 2 hours.

[0041] Add 50mL of nonamethyltrisilazane dropwise to the stirred tank, raise the temperature to 50°C, stir for 0.5h, continue to raise the temperature to 65°C, turn on the vacuum pump to maintain a vacuum of -0.8bar, concentrate in vacuo until the displayed weight of the stirred tank is 40kg, stop heating, Naturally lower the temperature to 40°C, turn on the circulating refrigerant and continue to cool down...

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Abstract

The invention provides a purification method of lithium difluorophosphate, and the purification method comprises the following steps: S1: in an inert gas protective atmosphere, dissolving a lithium difluorophosphate crude product by using an organic solvent, removing water by using a molecular sieve, and filtering by using a precision filter to obtain a lithium difluorophosphate solution of whichthe water content is less than 5ppm and the insoluble substance content is less than 200ppm; S2, adding a deacidifying agent into the lithium difluorophosphate solution obtained in the step S1 to obtain a lithium difluorophosphate solution of which the acid value(based on HF)is lower than 10ppm; S3, recrystallizing the lithium difluorophosphate solution obtained in the step S2 to obtain lithium difluorophosphate solid particles of which the impurity metal ion content is lower than 1ppm; and S4, drying and crushing the lithium difluorophosphate obtained in the step S3 to obtain a lithium difluorophosphate particle product with extremely low contents of water, free acids, insoluble substances and metal ions. The method can effectively remove water, acids and metal impurities of lithium difluorophosphate with poor quality, reduce the content of insoluble substances and improve the product quality of the lithium difluorophosphate.

Description

[technical field] [0001] The invention relates to a method for purifying lithium difluorophosphate, which belongs to the technical field of lithium ion batteries. [Background technique] [0002] Lithium difluorophosphate is used as an electrolyte additive for lithium-ion batteries to significantly improve the electrochemical performance. The research results show that adding lithium difluorophosphate to the lithium hexafluorophosphate electrolyte system can reduce the electrode polarization, and at the same time significantly improve the battery's normal temperature, high temperature cycle stability and high temperature storage performance. In addition, the lithium difluorophosphate additive is beneficial to the diffusion and charge transfer of lithium ions on the interface between positive and negative electrodes. Therefore, lithium difluorophosphate will have high industrial value as an electrolyte additive for lithium ion batteries. [0003] In the actual production pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/455H01M10/0525H01M10/0567
CPCC01B25/455H01M10/0525H01M10/0567C01P2006/80C01P2006/82Y02E60/10
Inventor 徐辑亮毛冲戴晓兵
Owner ZHUHAI SMOOTHWAY ELECTRONICS MATERIALS
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