Lithium ion battery and electrolyte thereof

Abstract

The present invention discloses a lithium ion battery and an electrolyte thereof, wherein the lithium ion battery electrolyte contains a non-aqueous organic solvent, a lithium salt, film forming additives such as vinylene carbonate and ethylene sulfate, and a phosphonate derivative flame retardant additive, and the weight content of the phosphonate derivative flame retardant additive in the electrolyte is 0.1-20%. According to the present invention, the lithium ion battery electrolyte contains the phosphonate derivative flame retardant additive, such that the flame retardant property of the electrolyte can be significantly improved, and the first time efficiency, the rate and the cycle performance of the lithium ion battery cannot be affected.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, more specifically, the invention relates to a lithium ion battery electrolyte with good flame retardancy and a lithium ion battery containing the electrolyte. Background technique [0002] Safety issues are the main obstacles restricting the development of lithium-ion batteries in the direction of large-scale and high-energy. Due to the defects of existing electrolyte systems, safe electrolyte systems have attracted more and more attention, and have become a hot spot in the research and development of lithium-ion battery electrolytes. [0003] Safe electrolyte systems can be divided into flame-retardant electrolytes, ionic liquid electrolytes and solid electrolytes. Among them, flame-retardant electrolytes are functional electrolytes, and flame-retardant functions are generally obtained by adding flame-retardant additives to conventional electrolytes. [0004] At present, the research on fla...

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Problems solved by technology

[0005] CN10193808A discloses an alkyne-containing phosphate flame retardant, which has good electrochemical performance, but the compatibility with the negative electrode needs to be improved

[0006] CN101079504A, CN101079505A, CN101445515A, and CN101071863A disclose the introduction of P-C bonds in the phosphoric acid ester structure to obtain phosphorous acid esters (such as methyl methyl phosphate, ethyl diethyl phosphate and derivatives thereof) as pure solvents or components of solvents Lithium-ion battery flame-retardant electrolyte, phosphite electrolyte has the characteristics of low price, non-combustibility, low toxicity, high conductivity and good electrochemical stability, but the combination of this type of organic phosphorus compound and graphite carbon negative electrode poor compatibility

However, the generated SEI film has a large impedance, which has a great influence on the rate and cycle performance of the battery cell, and is difficult to be used as a commercial electrolyte.

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