Lithium battery electrolyte based on sulfate additive

An additive and sulfate technology, applied in the field of lithium battery electrolyte and new energy materials, can solve the problems of dendrite growth and low coulombic efficiency, and achieve the effect of easy large-scale continuous production, easy manufacturing and strong universality

Inactive Publication Date: 2017-11-17
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problems of dendrite growth and low coulombic efficiency produced by metal lithium negative electrodes during the charge

Method used

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  • Lithium battery electrolyte based on sulfate additive
  • Lithium battery electrolyte based on sulfate additive
  • Lithium battery electrolyte based on sulfate additive

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0038] Example 1: 1M LiPF with dimethyl sulfate added 6 EC / DMC (v=1:1) electrolyte lithium deposition / precipitation efficiency

[0039] In an inert atmosphere, 1wt% of dimethyl sulfate was added to the commercially available 1M LiPF 6 In the EC / DMC (v=1:1) solution, prepare a ready-to-use electrolyte. According to the order of the positive battery case, the copper pole piece, the diaphragm, the lithium metal pole piece, and the negative battery case, inject the ready-to-use electrolyte, and assemble the button battery in the glove box.

[0040] The assembled button cell constitutes a copper and lithium two-electrode system. The lithium metal pole piece is used as the reference and auxiliary electrode, and the copper pole piece is used as the working electrode. The deposition and precipitation process of lithium metal on the current collector can be examined. This process can be analyzed , Can judge the reversibility and efficiency of the deposition and precipitation process, so a...

Example Embodiment

[0042] Example 2: 1M LiPF with dimethyl sulfate added 6 Scanning electron microscope topography of lithium deposition / precipitation in EC / DMC (v=1:1) electrolyte

[0043] Using the method of Example 1, disassemble the button cell after 20 weeks of circulation in the glove box, take out the copper pole piece, wash the pole piece with dimethyl carbonate, dry it, and place it under a scanning electron microscope for observation. Such as image 3 Shown. The control group without sulfate ester additives showed a typical lithium deposition morphology. Needle-like dendrites with a diameter of about 200nm were deposited on the copper current collector. The growth of such dendrites would pierce the separator and cause the inside of the battery. Short circuit causes serious safety problems. After adding the sulfuric acid ester additive, after the electrolyte was circulated for 20 weeks, the morphology of the lithium deposit was dendrites about 5 μm tumor-like particles, and the growth of...

Example Embodiment

[0044] Example 3: 1M LiTFSI DOL / DME (v=1:1)+1% LiNO added with diethyl sulfate 3 Lithium deposition / extraction efficiency of electrolyte

[0045] In an inert atmosphere, add diethyl sulfate to 1M LiTFSI DOL / DME (v=1:1)+1% LiNO 3 In the electrolyte, its mass fraction is 3.8%. The Li|Cu button cell was assembled according to the method in Example 1, and the electrochemical performance test was performed.

[0046] Figure 4 It is 1M LiTFSI DOL / DME (v=1:1)+1% LiNO added with diethyl sulfate 3 Cycle life diagram of Li|Cu battery of electrolyte. From Figure 4 It can be seen that the deposition / precipitation efficiency of the blank control example was only 91.2% in the first week, while the electrolyte with the diethyl sulfate additive increased to 95.1% in the first week. At the same time, the number of cycles of Li|Cu batteries added with the electrolyte of diethyl sulfate increased from 40 to 100 weeks, an increase of 2.5 times. Prove that the sulfate additives are in 1M LiTFSIDOL / D...

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Abstract

The invention discloses a lithium battery electrolyte based on a sulfate additive. The lithium battery electrolyte comprises a solvent A, a lithium salt B and a sulfate additive C. The sulfate additive C is used for participating in the formation of SEI on the surface of a lithium metal negative electrode, and decoration/modification is carried out on the SEI film on the surface of the electrode; the sulfate additive C comprises the components such as ethylene sulfate, 4-methyl-1,3,2-dioxathiolane 2-oxide and trimethylene sulfite and has relatively low lowest unoccupied molecular orbital energy, electrons are easily obtained, the components are reduced more easily, and a decomposition product of the additive is rich in Li2S and Li2O, inorganic constituents are introduced on the surface of the lithium negative electrode, the mechanical strength of the SEI is improved by regulating and controlling the constituents of the SEI, so that the stability of the SEI is improved, and then the growth of lithium dendrites is inhibited, the service life of a lithium metal battery is prolonged, and the cycle performance of the lithium metal battery is improved.

Description

technical field [0001] The invention relates to a lithium battery electrolyte based on a sulfuric acid ester additive, which belongs to the field of lithium batteries and also belongs to the field of new energy materials and technologies. Background technique [0002] "Lithium metal battery" is a type of battery that uses lithium metal or lithium alloy as the negative electrode material and uses a non-aqueous electrolyte solution. Lithium metal density is small (0.59g / cm -3 ), low negative potential (-3.040V vs. SHE), and high theoretical specific capacity (3860mAh / g), which is 10 times that of graphite electrodes (372mAh / g) used in traditional lithium-ion batteries. Therefore, lithium metal batteries are expected to become A new generation of high energy density batteries. [0003] The main problems currently faced by lithium metal batteries are dendrite growth on the lithium surface and low Coulombic efficiency. The generation of lithium dendrites is mainly due to defec...

Claims

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Application Information

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IPC IPC(8): H01M10/0567H01M10/052H01M12/08
CPCH01M10/052H01M10/0567H01M12/08H01M2300/0025Y02E60/10
Inventor 钱江锋万国佳艾新平杨汉西
Owner WUHAN UNIV
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