Method for preparing difluorine oxalic acid boracic acid lithium

A technology of lithium difluorooxalate borate and oxalate, which is applied in the field of electrolyte salt manufacturing, can solve problems affecting battery power characteristics, poor low-temperature performance, large resistance, etc., achieve good low-temperature cycle performance, improve high-temperature cycle performance, and good The effect of battery rate capacity

Inactive Publication Date: 2008-03-12
ZHANGJIAGANG GUOTAI HUARONG NEW CHEM MATERIALS CO LTD
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  • Abstract
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AI Technical Summary

Problems solved by technology

However, LiBOB also has some disadvantages, such as low solubility and high viscosity in alkyl carbonate solvents, resulting in poor electrical conductivity and poor low-temperature performance; in addition, the SEI film formed by using LiBOB salt has a large resistance, It affects the power characteristics of the battery, especially the power performance under low temperature conditions, so to some extent limits the extensive application of LiBOB in lithium-ion batteries
Lithium tetrafluoroborate (LiBF 4 ) is used as an electrolyte salt for lithium-ion batteries, which can significantly improve the low-temperature performance of lithium-ion batteries, but there are a series of problems such as low conductivity, poor thermal stability and easy hydrolysis
Therefore, looking at the development of lithium-ion battery electrolytes, it is difficult for commercially used electrolytes to simultaneously meet the high-temperature and low-temperature performance requirements of lithium-ion batteries.

Method used

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  • Method for preparing difluorine oxalic acid boracic acid lithium

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Lithium difluorooxalate borate was prepared from boron trifluoride ether solution and lithium oxalate.

[0015] Step 1. Add 101.9g of lithium oxalate dried at 120°C for 4 hours in a dry reactor equipped with an electric stirrer and a thermometer, slowly drop in 158g of boron trifluoride ether solution, heat and stir to mix the raw materials as much as possible, and then seal The reactor was heated to 80°C for 48 hours at a constant temperature to fully react boron trifluoride and lithium oxalate to generate lithium difluorooxalate borate and lithium fluoride, and then cooled to room temperature.

[0016] Step 2, filter the reacted mixture at room temperature to remove unreacted lithium oxalate and lithium fluoride solids generated after the reaction, extract the mother liquor several times with dimethyl carbonate, concentrate under reduced pressure, cool and crystallize, and then use dicarbonate Methyl esters are subjected to a recrystallization process to remove residu...

Embodiment 2

[0021] Lithium difluorooxalate borate was prepared from lithium hydroxide, oxalic acid and boron trifluoride ether solution.

[0022] Step 1. Dissolve 47.9g of lithium hydroxide in distilled water, gradually add 140g of oxalic acid crystals, start the stirring device at the same time, slowly drop in 173.1g of boron trifluoride ether solution after it is completely dissolved, seal the reactor, and heat the whole mixture to 86° C. and kept at constant temperature for 54 hours to fully react, then cooled to room temperature.

[0023] Step 2: filter the reacted mixture at room temperature, extract the mother liquor several times with dimethyl carbonate, concentrate under reduced pressure, cool and crystallize, and then carry out recrystallization process with acetonitrile solution to remove residual impurities.

[0024] Step 3: The recrystallized product was dried at 180° C. for 48 hours under a vacuum degree of −0.08 MPa to finally obtain 129.6 g of the product, whose purity was ...

Embodiment 3

[0028] Take LiMn 2 o 4 As the positive electrode, graphite is the lithium-ion battery assembled as the negative electrode in 1mol / L LiODFB propylene carbonate / ethylene carbonate / ethyl methyl carbonate (1: 2: 1wt%) cycle performance test results are shown in Figure 1. The analysis shows that the capacity retention rate of the lithium-ion battery is 90% after 300 cycles at 1C at 60°C, and 85.4% after 300 cycles at 1C at 0°C. It can be seen that the lithium ion battery using LiODFB as the electrolyte has good high and low temperature cycle performance.

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Abstract

The present invention discloses a preparation method of the difluoride lithium oxalate borate. The method is characterized in that the compounds containing the fluorin, boron, lithium and oxalate react at a certain temperature and under a certain pressure to produce the crude material of the difluoride lithium oxalate borate; then the organic solvent is used for extracting and purifying; finally, the recrystallization and vacuum drying are done to get the battery-level lithium fluoride oxalate borate. The advantage is that the preparation method of the difluoride lithium oxalate borate can improve the high-temperature and low-temperature performance, the cycle performance, power characteristics and other comprehensive performances of the lithium-ion battery.

Description

technical field [0001] The invention relates to the technical field of manufacturing electrolyte salts used in lithium ion batteries, in particular to a preparation method of electrolyte salt lithium difluorooxalate borate. Background technique [0002] Electrolyte salt is an important part of lithium-ion electrolyte, which has a great influence on the performance of lithium-ion batteries. In recent years, lithium hexafluorophosphate (LiPF 6 ) are widely used in the study of electrolyte salts for lithium-ion batteries. LiPF 6 It has the advantages of good ionic conductivity and electrochemical stability, simple disposal of waste batteries, little environmental pollution, etc., and has good compatibility with the positive and negative electrodes of the battery. However, its thermal stability is poor and it is easy to decompose into LiF and PF 5 , while PF 5 Easily hydrolyzed to form HF and POF 3 , these two hydrolyzed products have high reactivity to both positive and n...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F5/02C07C55/07
Inventor 骆宏钧周冬兰
Owner ZHANGJIAGANG GUOTAI HUARONG NEW CHEM MATERIALS CO LTD
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