Electrolyte and preparation method therefor, and lithium-sulfur battery

Abstract

The invention provides an electrolyte and a preparation method therefor, and a lithium-sulfur battery prepared by adopting the electrolyte. The electrolyte comprises an electrolyte lithium salt, a non-aqueous organic solvent and an ether group functional group-containing ionic liquid. By taking the ether group functional group-containing ionic liquid as a solvent, the vapor pressure of the electrolyte can be obviously lowered, and the flame retardancy of the electrolyte can be improved; and by virtue of the existence of the ether group functional group, the dissolvability and degree of dissociation of the lithium salt in the electrolyte can be promoted.

Description

technical field [0001] The invention relates to the field of preparation of lithium battery electrode materials, in particular to an electrolytic solution and a preparation method thereof, and a lithium-sulfur battery prepared by using the electrolytic solution. Background technique [0002] With the rapid development of compact portable electronic devices and power batteries, the demand for high energy density batteries is increasing. Elemental sulfur has a high theoretical specific capacity (1675mAh / g) and specific energy (2600Wh / kg), which is more than five times the theoretical energy density of traditional lithium-ion batteries. The actual energy density of lithium-sulfur batteries currently developed is 400~ 600Wh / kg, which is 2 to 3 times the actual energy density of commercial lithium-ion batteries. Elemental sulfur as a cathode material also has the advantages of abundant natural reserves, low price, and environmental friendliness. [0003] The lithium-sulfur batt...

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Problems solved by technology

[0003] The lithium-sulfur battery system is also the focus of extensive research in the current academic circles. It is generally believed that the main problems of lithium-sulfur batteries are: 1) The electronic conductivity of elemental sulfur is low

2) The S x n-anions generated during charging and discharging have strong nucleophilic ability, and there is interaction between them and solvents such as carbonate and LiPF 6 or electrolyte materials, so traditional lithium-ion battery electrolytes are not suitable for lithium ion batteries. Sulfur battery system, 3) polysulfides (Li2S x) (x=4~8) generated during charging and discharging will gradually dissolve into the electrolyte and shuttle between the positive and negative electrodes, resulting in the loss of positive active materials, At the same time, this is also an important factor for the low coulombic efficiency and fast capacity decay of lithium-sulfur batteries.

4) Using metal lithium as the negative electrode, there is a problem of lithium dendrites in the long cycle process

It has also been reported that the selection of solid-state electrolytes can partially inhibit the generation of dendrites (X.Liang, et al., Journal of Power Sources, 2011, 196, 3655), but the conductivity of organic all-solid-state electrolytes is low, resulting in the battery's low temperature at room temperature. Difficult to charge and discharge with high current

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