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Lithium-sulfur battery electrolyte and preparation method thereof

A lithium-sulfur battery and electrolyte technology, applied in the field of energy chemistry, can solve problems such as hindering the performance of Li-S batteries, inhibiting the conversion kinetics of sulfur species, and uneven precipitation activation energy, so as to improve the overall performance and high reactivity , the effect of improving the utilization rate

Pending Publication Date: 2021-10-22
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, the slow polysulfide conversion kinetics of the sulfur cathode seriously hinders the performance of Li–S batteries and has become one of the bottlenecks for the practical application of Li–S batteries.
Specifically, lithium polysulfide (LiPS), an intermediate product of Li–S batteries, has low diffusion capacity, limited solubility, and poor surface reactivity, which severely inhibit the conversion kinetics of sulfur species during discharge.
In addition, due to the accumulation of LiPS in the electrolyte, solid Li with high activation energy and poor conductivity will be precipitated unevenly on the surface of the positive electrode during the discharge process. 2 S, while large particles of Li 2 S is difficult to reuse in the subsequent process, which poses a huge obstacle for the transformation of sulfur species during charging.

Method used

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  • Lithium-sulfur battery electrolyte and preparation method thereof
  • Lithium-sulfur battery electrolyte and preparation method thereof
  • Lithium-sulfur battery electrolyte and preparation method thereof

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preparation example Construction

[0035] A method for preparing a lithium-sulfur battery electrolyte, the steps are as follows: under the protection of an inert gas, add a lithium salt to an organic solvent or a mixed organic solvent, then add a high-activity additive, stir well and evenly, and obtain the lithium-sulfur battery electrolyte ; The inert gas is at least one of nitrogen, helium and argon; the water content in the inert gas is <0.1ppm, and the oxygen content is <0.1ppm.

[0036] Lithium-sulfur battery electrolyte used in lithium-sulfur batteries. The lithium-sulfur battery includes a positive electrode sheet, a negative electrode sheet, a separator, and the lithium-sulfur battery electrolyte; the positive electrode sheet includes a positive electrode active material, a conductive agent, a current collector, and a binder; the negative electrode sheet includes a negative electrode active material and a binder. The positive electrode active material includes lithium sulfide and elemental sulfur. The ...

Embodiment 1

[0039] 1) Preparation of electrolyte

[0040] DOL and DME are mixed at a volume ratio of 1:1 to obtain an organic solvent;

[0041] Add LiTFSI and LiTfO to the organic solvent, and the concentrations of LiTFSI and LiTfO in the mixed solution of the organic solvent and the electrolyte salt are 1mol / L respectively; then add the additive LiNO 3 , LiNO 3 The mass fraction in the whole mixing system is 2wt%;

[0042] Finally, dimethyl diselenide was added, and its concentration in the mixed solution was controlled to be 50 mmol / L, which was the lithium-sulfur battery electrolyte of Example 1.

[0043] 2) Preparation of lithium-sulfur battery

[0044] Install the positive electrode sheet, electrolyte, separator, and negative electrode sheet in order, let it stand for 6 hours, discharge it to 1.7V with a constant current of 0.5C, and then charge it to 2.6V at a constant current to complete the preparation of the lithium-sulfur battery.

Embodiment 2

[0046] Electrolyte preparation

[0047] DOL and DME are mixed at a volume ratio of 1:1 to obtain an organic solvent;

[0048] Add LiBr and LiI to the organic solvent, and the concentrations of LiBr and LiI in the mixed solution of the organic solvent and the electrolyte salt are 1mol / L; then add the additive LiNO 3 , LiNO 3 The mass fraction in the whole mixing system is 2wt%;

[0049] Finally, diphenyl diselenide was added, and its concentration in the mixed solution was controlled to be 0.1 mmol / L, which was the lithium-sulfur battery electrolyte of Example 2.

[0050] The electrolyte was used to assemble a lithium-sulfur battery; the processes and parameters not indicated in this embodiment were the same as in Example 1.

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Abstract

The invention discloses a lithium-sulfur battery electrolyte and a preparation method thereof, belonging to the technical field of energy chemistry. The electrolyte comprises an organic solvent, a lithium salt and a high-activity additive, wherein the structure of the high-activity additive is one or more of organic sulfur, selenium and tellurium ethers of A-Sn-B, A-Sen-B or A-Ten-B. A series of high-activity additives containing one or more of Se-Se, S-S or Te-Te bonds are introduced, are subjected to reversible cracking and recombination during charging and discharging of the battery, act with an intermediate product polysulfide Li2Sx of the lithium-sulfur battery and participate in the oxidation-reduction process of sulfur, and organic polysulfides RSx + nLi, RSenSxLi or RenSxLi with excellent reactivity and diffusivity are generated to promote proceeding of reaction kinetics. Thus, the utilization rate of chemical oxidation active substances of lithium sulfide is improved, the reversibility, cycle performance and energy density of electrochemical reaction are improved, and the overall performance of the battery is improved.

Description

technical field [0001] The invention belongs to the technical field of energy chemistry, and in particular relates to a lithium-sulfur battery electrolyte and a preparation method thereof. Background technique [0002] The continuous development of human society is accompanied by the increasing demand for energy, but traditional fossil resources cannot meet the growing energy demand. The development and utilization of efficient new energy has become an important means to alleviate the pressure of environmental protection and ensure the security of energy structure. Battery systems play a vital role in the conversion and storage of new energy. [0003] In a variety of energy consumption scenarios including electric vehicles, consumer electronics, and smart grids, commercial lithium-ion batteries occupy a dominant position in energy storage systems, but their related performance indicators are close to the theoretical upper limit. Therefore, it is imperative to develop next-g...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0567H01M10/058H01M10/052
CPCH01M10/0567H01M10/058H01M10/052Y02P70/50Y02E60/10
Inventor 李西尧张强
Owner TSINGHUA UNIV
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