Phase variation electrolyte as well as preparation method and application thereof

Abstract

The invention provides a phase variation lithium ion electrolyte comprising the following components of lithium salts and organic compounds containing acid amide functional groups. The invention also provides a preparation method of the electrolyte, comprising the following steps: a. mixing the lithium salts and the organic compounds containing acid amide functional groups; b. heating the mixtureand melting the mixture to obtain transparency liquid; and c. cooling the transparency liquid to obtain the electrolyte, wherein the steps a, b and c are operated in dry environments. The phase variation lithium ion electrolyte is applied to chargeable and dischargeable lithium batteries. In addition, the invention also provides a chargeable and dischargeable lithium battery comprising the electrolyte. The electrolyte has lower electrical conductivity and higher thermal and chemical stability when being a solid under the condition that the temperature is lower than a phase variation temperature and has higher electrical conductivity when being liquid under the condition that the temperature is higher than the phase variation temperature.

Description

technical field [0001] The invention relates to a phase transition electrolyte and a preparation method and application of the electrolyte, belonging to the technical field of materials. Background technique [0002] Due to many natural disasters, we put forward higher requirements for energy storage methods. The large-scale snow disaster that occurred in the south of my country in early 2008 caused a large-scale power supply shortage; Large-scale earthquakes will cause damage to the power grid. If the power grid fails to work normally, the distributed power system will still work, which will be conducive to power supply in emergency situations. Therefore, in addition to lithium-ion batteries with high energy density and high power density, research on long-life energy storage lithium-ion batteries has gradually attracted attention. From the perspective of clean energy, the two highly respected new energy sources are solar energy and wind energy, but their disadvantage is th...

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Problems solved by technology

In "Journal of Electrochemistry (J.Electrochem.Soc)" 2001, No. 148, page 1100 and "Chemical Review" (Chemical Review) 2004, No. 104, pages 4303-4417 disclosed that LiPF 6 There are two significant shortcomings in the electrolyte as a lithium salt: (1) thermal instability, the reason is that in the solution, the anion PF 6 - There is an equilibrium: LiPF 6 →LiF+PF 5 (I), and LiF belongs to strong Lewis acid, it and PF 5 Both tend to react with organic solvents and cause the equilibrium to go to the right; (2) At the same time, the P-F bond is very sensitive to water, even a trace amount of water will trigger the following reaction: LiPF 6 +H 2 O→POF 3 +LiF+2HF(II), PF 5 +H 2 O→POF 3 +2HF(III), the HF produced by formula (II) and formula (III) will promote the dissolution of the positive electrode material, so that its lithium storage capacity will gradually decay

[0005] At the same time, for the current lithium-ion energy storage battery, the use of liquid organic electrolyte has a certain self-discharge rate in the process of storing energy, which is easy to cause energy loss

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