Electrolyte capable of being used for lithium metal secondary battery and application of electrolyte

A secondary battery and electrolyte technology, applied in secondary batteries, secondary battery repair/maintenance, organic electrolytes, etc., can solve the problems of shortening battery life, easily generating dendrites, affecting battery coulomb efficiency, etc. The effect of deposition overpotential, simple preparation steps and excellent safety performance

Pending Publication Date: 2022-01-25
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the application of lithium metal anodes is still facing great challenges.
On the one hand, metal lithium is prone to produce dendrites during the deposition process, which will pierce the separator in severe cases, resulting in a short circuit of the battery and even a safety accident.
On the other hand, the infinite volume expansion of Li metal leads to poor interfacial stability, which seriously affects the cycle performance of batteries.
In addition, the extremely active lithium metal has side reactions with the organic electrolyte, and the unstable solid electrolyte membrane (SEI) will further consume a large amount of lithium metal and electrolyte, which will eventually affect the Coulombic efficiency of the battery and shorten the battery life.

Method used

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  • Electrolyte capable of being used for lithium metal secondary battery and application of electrolyte
  • Electrolyte capable of being used for lithium metal secondary battery and application of electrolyte
  • Electrolyte capable of being used for lithium metal secondary battery and application of electrolyte

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] In a glove box filled with inert gas (argon), add phenylphosphonic acid to carbonate electrolyte (0.01MLiAsO 6dissolved in EC / DMC / FEC (volume ratio 1:1:1, total volume 100ml), made into an electrolyte solution with a mass fraction of phenylphosphonic acid of 0.1%, and stirred for 10 minutes to obtain the phenylphosphonic acid-containing Phosphonic acid electrolyte. The electrolyte prepared by this method is used to assemble Li||Li symmetrical battery, and the separator is PE. After the battery was cycled for 50 cycles, the surface of the electrode without phenylphosphonic acid in the electrolyte appeared obvious dendrite morphology ( figure 1 ), while the electrode surface with phenylphosphonic acid added to the electrolyte remained flat after 50 cycles. in figure 1 a and figure 1 b is the surface morphology of the electrode without adding phenylphosphonic acid, figure 1 c and figure 1 d is the surface morphology of the electrode added with phenylphosphonic acid. ...

Embodiment 2

[0042] In a glove box filled with inert gas (helium), add phenylphosphonic acid to ester electrolyte (0.5M LiPF 6 dissolved in EC / DMC / FEC (volume ratio 1:1:1, total volume 100ml), made into an electrolyte solution with a mass fraction of phenylphosphonic acid of 0.5%, and stirred for 30 minutes to obtain the phenylphosphonic acid-containing Phosphonic acid electrolyte. The electrolyte solution prepared by this method is used to assemble Li||Li symmetrical battery, and the separator is PE / PP. figure 2 After assembling the battery for the above-mentioned electrolyte solution containing 0.5wt.% phenylphosphonic acid, at a current density of 0.5mA / cm 2 , the deposition capacity is 0.5mAh / cm 2 Under the same conditions, the voltage-time diagram of the battery is stable for 480 hours, the polarization voltage is lower than 60mV, and the charge-discharge curve is stable.

Embodiment 3

[0044] Under the protection of an inert gas (helium), add phenylphosphonic acid to the ester electrolyte (1M LiBF4 dissolved in EMC / DMC / DEC, volume ratio 1:1:1, total volume 100ml) to form phenyl The solution with a mass fraction of phosphonic acid of 1% was stirred for 1 h until it was completely dissolved, and the electrolyte solution containing phenylphosphonic acid described in the present invention was obtained. The electrolyte prepared by this method is used to assemble Li||Cu batteries, with PP film as the separator, and the battery operates at 1mA / cm 2 Under the current density of , after one hour of discharge, the lithium deposited on Cu foil as image 3 shown. The results of SEM showed that the deposition of lithium on the copper foil was very uniform after adding the phenylphosphonic acid additive, and the deposited lithium showed a spherical shape; the lithium deposition on the copper foil without the additive was very uneven and showed a rod shape.

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Abstract

The invention discloses an electrolyte capable of being used for a lithium metal secondary battery and application of the electrolyte. The electrolyte can enable the lithium metal secondary battery to show better cycling stability and rate capability. The electrolyte comprises a lithium salt, an organic solvent and an additive, the lithium salt is dissolved in the organic solvent, the organic solvent is an ester solvent, and the additive is phenylphosphonic acid. According to the invention, the phenyl phosphonic acid additive is introduced into the electrolyte, and through the coordination reaction of the additive and lithium ions in the electrolyte, the deposition overpotential of the lithium metal is increased, the particle size of the deposited lithium metal is refined, the interface stability of the lithium metal is improved, and the cycle life of the lithium metal battery is finally prolonged. The preparation process is simple, large-scale production is easy, and the use requirement of the lithium metal negative electrode in a high-energy-density rechargeable battery can be met.

Description

technical field [0001] The invention is applied in the fields of lithium metal secondary batteries and electrochemistry, and relates to an electrolyte solution for lithium metal secondary batteries containing additives and a preparation method thereof. Background technique [0002] Lithium-ion secondary batteries are the most promising electrochemical energy storage devices in the 21st century because of their high discharge capacity, high energy density, small size, light weight, no memory effect, clean and renewable, and many other advantages. Lithium-ion secondary batteries The research and development and application of the technology are conducive to solving the problem of environmental pollution and alleviating the fossil energy crisis. With the continuous progress of society, the demand for new energy vehicles to replace traditional internal combustion engine-driven vehicles continues to increase. The rapid development of new information and communication technologies...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/42
CPCH01M10/0567H01M10/4235H01M2300/0025Y02E60/10
Inventor 欧阳柳章邹品娟曾美琴朱敏
Owner SOUTH CHINA UNIV OF TECH
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