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A kind of electrolyte additive for lithium metal negative electrode protection and its preparation method and application

An electrolyte and additive technology, applied in the field of electrolyte additives for lithium metal anode protection and their preparation, can solve the problems of uneven deposition, uneven current density distribution, potential safety hazards, etc., so as to improve deposition dissolution efficiency and inhibit growth. , the effect of improving safety

Active Publication Date: 2019-11-01
SUZHOU UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are some problems restricting the application of lithium as follows: (1) Lithium metal has high activity and almost reacts with most organic solvents, thus forming an SEI film at the interface between lithium metal and electrolyte. As the process progresses, the SEI film gradually thickens, the interface impedance continues to increase, the Coulombic efficiency decreases, and the battery capacity decays; (2) The SEI film is unstable, and it continuously breaks-falls-regenerates during the process of lithium intercalation and deintercalation, consuming metal lithium and electrolysis (3) The uneven distribution of current density during the lithium deposition-extraction process leads to uneven deposition and the formation of lithium dendrites, causing safety hazards and irreversible capacity loss caused by "dead lithium"
This method has a certain effect, but because it is difficult to make the artificially synthesized polymer electrolyte membrane thin enough, a relatively thick interface layer will produce a large internal resistance, and as time goes by, the actual application of the battery The electrochemical performance has a great influence

Method used

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  • A kind of electrolyte additive for lithium metal negative electrode protection and its preparation method and application
  • A kind of electrolyte additive for lithium metal negative electrode protection and its preparation method and application
  • A kind of electrolyte additive for lithium metal negative electrode protection and its preparation method and application

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] Preparation of LiTCNQ:

[0057] Weigh 1g TCNQ and 1.02g LiI, grind them evenly, then add them into 50mL acetonitrile solution and stir for 40min. React at 60-80°C, when the color of the solid product changes from yellow to purple, the reaction is completed, filter, wash the resulting product with acetonitrile, and finally recrystallize in ethanol solution, dry the resulting solid in a vacuum oven at 80°C for 12 hours, That is LiTCNQ with a purity of 98.5% to 99.5%.

[0058] LiTCNQ characterization:

[0059] Do IR test to gained LiTCNQ, and compare with the IR spectrogram of raw material TCNQ, as figure 1 Shown, as can be seen from this figure, the compound (LiTCNQ) shown in formula (I) is synthesized successfully.

[0060] Carry out XRD test to the obtained LiTCNQ, the XRD figure is as follows figure 2 As shown, the results show that the prepared LiTCNQ is in crystalline form, and its X-ray diffraction pattern has characteristic peaks at 2theta of 10.5°, 15.2°, 17°...

Embodiment 2

[0068] LiTCNQ application:

[0069] Weigh 0.005g of LiTCNQ prepared by the method of Example 1, add to 1mL 1M LiPF 6 In the EC / EMC / DMC electrolyte (purchased from Zhangjiagang Guotai Huarong Chemical New Material Co., Ltd.), the small magnet was stirred for 30 minutes until the dissolution was complete, and the lithium battery electrolyte of the present invention (LiTCNQ accounted for 100% of the mass of the lithium battery electrolyte) was obtained. Min content is 0.2%-0.25%).

[0070] to LiPF 6 The stability of metal lithium on copper foil and the deposition and dissolution curve of metal lithium on copper foil in Li / Cu batteries with EC / EMC / DMC electrolyte were tested, and the specific performance is capacity (charge and discharge at 0.5mA for 2h) and Coulombic efficiency, the results see Figure 7 with 8 .

[0071] The stability of metal lithium on the copper foil and the deposition and dissolution curve of metal lithium on the copper foil in the Li / Cu battery of th...

Embodiment 3

[0074] LiTCNQ application:

[0075]Weigh 0.005g of LiTCNQ prepared according to the method of Example 1, add it to 1mL 1M LiTFSI DOL / DME electrolyte (purchased from Zhangjiagang Guotai Huarong Chemical New Material Co., Ltd.), stir for 30min with a small magnet until it dissolves completely, and obtain The lithium battery electrolyte of the present invention (LiTCNQ accounts for 0.2%-0.25% by mass of the lithium battery electrolyte).

[0076] The stability of metal lithium on copper foil and the deposition and dissolution curve of metal lithium on copper foil in Li / Cu batteries with LiTFSI DOL / DME electrolyte were tested, specifically expressed as capacity (charge and discharge at 0.5mA for 2h) and Coulombic efficiency, the results see Figure 11 with 12 .

[0077] The stability of metal lithium on the copper foil and the deposition and dissolution curve of metal lithium on the copper foil in the Li / Cu battery of the lithium battery electrolyte of the present invention have...

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Abstract

The invention discloses an electrolyte additive for protecting a lithium metal negative electrode and a preparation method and application of the electrolyte additive. The electrolyte additive is a compound as shown in a formula (1): the formula (1) is as shown in the specification. The preparation method comprises the following step of reacting a reducing lithium salt with 7,7,8,8-tetracyanoquinodimethane in an organic solvent to obtain the compound as shown in the formula (1); and the application comprises an application of the compound as shown in the formula (1) in a lithium battery electrolyte and an application of the lithium battery electrolyte containing the compound as shown in the formula (1) in a lithium battery. According to the compound as shown in the formula (1), growth of lithium dendrites can be effectively inhibited and the deposition and dissolution efficiency of lithium is improved, thereby improving the cycle stability and the security of the lithium battery.

Description

technical field [0001] The invention belongs to the field of new energy materials, and in particular relates to an electrolyte additive for lithium metal negative electrode protection, a preparation method and application thereof. Background technique [0002] At this stage, LiFePO is used in commercial batteries 4 ,LiCoO 2 , Li 2 MnO 3 A transition metal compound is used as the positive electrode, and graphite or hard carbon is used as the negative electrode. Whether it is a transition metal compound positive electrode or a graphite negative electrode, their theoretical specific capacity does not exceed 400mAh / g, and the energy density of the battery is limited. With the development of electric vehicle technology, people have higher and higher requirements for battery energy density, and the current commercial batteries can no longer meet the energy density requirements of power batteries. Therefore, in recent years, Li-S, Li-O 2 High energy density battery systems su...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M10/0567H01M10/052H01M10/42C07C255/33C07C253/30
CPCC07B2200/13C07C255/33H01M10/052H01M10/0567H01M10/4235Y02E60/10
Inventor 李长明邓雯雯
Owner SUZHOU UNIV OF SCI & TECH
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