Safe low-concentration electrolyte for lithium battery and application of safe low-concentration electrolyte

A lithium battery and electrolyte technology, which is applied in the field of low-concentration electrolyte for lithium batteries, can solve the problems of not being able to balance high performance and high safety, and reduce the cost of electrolyte, so as to improve cycle stability and reduce the amount of free solvent molecules , the effect of high commercialization prospects

Pending Publication Date: 2022-01-18
ANHUI UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to overcome the problem that the low-concentration electrolyte in the prior art cannot take into account high performance and high safety. It intends to provide a safe low-concentration electrolyte for lithium batteries and its application. The idea is to adjust the solvation structure, interface structure and physical and chemical properties of the electrolyte at the same time. The present invention achieves a low-concentration electrolyte that can make the lithium battery stable and safe by rationally designing the composition of lithium salts, solvents and co-solvents. Compared with the traditional electrolyte, the electrolyte has a lower lithium salt concentration, which can significantly reduce the cost of the electrolyte, and finally obtain a low-cost, high-performance, high-safety electrolyte for lithium batteries

Method used

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  • Safe low-concentration electrolyte for lithium battery and application of safe low-concentration electrolyte
  • Safe low-concentration electrolyte for lithium battery and application of safe low-concentration electrolyte
  • Safe low-concentration electrolyte for lithium battery and application of safe low-concentration electrolyte

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] The lithium salt concentration is respectively configured as 0.6M without co-solvent (specifically 0.3M LiDFOB+0.3M LiBF 4 dissolved in FEC solvent) and 0.6M added co-solvent (specifically 0.3M LiDFOB+0.3M LiBF 4 Dissolved in the mixed solvent of FEC / TTE, the volume ratio of FEC and TTE is 1:1) low-concentration electrolyte, using the above electrolyte, lithium sheet, copper sheet, and diaphragm to assemble into a lithium-copper half-cell, and at 1mA cm -2 The Coulombic efficiency test is carried out under the current density, such as figure 1 As shown, in the 0.6M no co-solvent control group, the average coulombic efficiency of the lithium anode was lower than 90%, while in the 0.6M co-solvent addition experimental group, the average coulombic efficiency of the lithium anode was close to 100%. This example demonstrates that the addition of co-solvents has an important effect on the properties of low-concentration electrolytes.

Embodiment 2

[0045] The concentration of lithium salt is respectively configured as 1M without co-solvent (specifically 0.5M LiDFOB+0.5M LiBF 4 soluble in FEC solvent), 2M without co-solvent (specifically 1M LiDFOB+1M LiBF 4 dissolved in FEC solvent) and 0.6M added co-solvent (specifically 0.3M LiDFOB+0.3M LiBF 4 Dissolved in the FEC / TTE solvent, the volume ratio of FEC and TTE is 1:1) low-concentration electrolyte, using the above electrolyte, lithium sheet, copper sheet, and diaphragm to assemble into a lithium copper half-cell, and at 1mA em -2 The Coulombic efficiency test is carried out under the current density, such as figure 2 As shown, in the 1M no co-solvent control group, only 10 weeks of stable circulation can be achieved, while the performance of the 0.6M co-solvent addition experimental group and the 2M no co-solvent control group is similar, and the lithium anode can be stably circulated. This example shows that by adding a co-solvent to a low-concentration electrolyte, e...

Embodiment 3

[0047] Configure the lithium salt concentration as a single lithium salt (specifically 0.6M LiBF 4 Dissolved in FEC / TTE solvent, the volume ratio of FEC and TTE is 1:1) and mixed lithium salt (specifically 0.3M LiDFOB+0.3M LiBF 4 Dissolved in the solvent of FEC / TTE, the volume ratio of FEC and TTE is 1:1) low-concentration electrolyte, using the above electrolyte, lithium sheet, copper sheet, and diaphragm to assemble into a lithium copper half-cell, and at 1mA cm -2 The Coulombic efficiency test is carried out under the current density, such as image 3 As shown, in the single lithium salt control group, the coulombic efficiency of the lithium anode gradually decreases, while in the mixed lithium salt experimental group, the coulombic efficiency of the lithium anode can remain stable. This example shows that the use of mixed lithium salts in low-concentration electrolytes has superior performance over single lithium salts.

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Abstract

The invention discloses a safe low-concentration electrolyte for a lithium battery and application of the safe low-concentration electrolyte, and belongs to the field of secondary batteries. The electrolyte contains lithium salt, a solvent for dissolving the lithium salt and a non-solvated cosolvent, the lithium salt is a mixed lithium salt rich in fluorine element, the overall concentration of the lithium salt does not exceed 0.6 mol/L, the solvent is a single solvent or a mixed solvent, the cosolvent is a fluorinated solvent, and the electrolyte has a flame-retardant effect. The problem that in the prior art, a low-concentration electrolyte cannot give consideration to high performance and high safety at the same time is solved, the low-concentration electrolyte capable of enabling a lithium battery to stably circulate and be safe is achieved by reasonably designing the components of the lithium salt, the solvent and the cosolvent, and compared with a traditional electrolyte, the electrolyte has the advantages that the lithium salt concentration is lower, the cost of the electrolyte can be remarkably reduced, and the electrolyte for the lithium battery, which is low in cost, high in performance and high in safety, is finally obtained.

Description

technical field [0001] The invention relates to the technical field of secondary batteries, in particular to a safe low-concentration electrolyte for lithium batteries and its application. Background technique [0002] Metal lithium has the highest theoretical specific capacity (3860mAh / g) and the lowest redox potential (-3.04V vs. standard hydrogen electrode), so lithium metal batteries that directly use metal lithium as the negative electrode are regarded as the next generation of high energy density batteries. However, the large-scale application of lithium metal batteries is facing severe challenges. On the one hand, the uneven deposition and unstable interface of the lithium anode during cycling will lead to a rapid decline in the capacity of the anode and potential safety issues. On the other hand, the structure of the cathode The destruction of the active material will lead to the loss of active material and the failure of the battery. [0003] The electrolyte is in ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/052H01M10/0569
CPCH01M10/052H01M10/0569H01M10/0567H01M2300/0025Y02E60/10
Inventor 姜智鹏莫季生李永涛张庆安
Owner ANHUI UNIVERSITY OF TECHNOLOGY
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