Mixed lithium salt electrolyte

Abstract

The invention discloses a mixed lithium salt electrolyte. The mixed lithium salt electrolyte is prepared from a dinitrile additive, an ether additive, a carbonic ester additive, lithium nitrate and lithium hexafluorophosphate. According to the invention, ADN, anisole, VC and lithium nitrate are used as functional additives; the viscosity of the electrolyte is adjusted through ADN; the formation ofan SEI film is promoted; anisole is reacted with a reduction product of a solvent; the generated LiOCH3 is beneficial to generation of an efficient and stable SEI film on the surface of the electrode, VC inhibits stripping of a graphite negative electrode caused by PC co-insertion, and the cycle performance of the battery is improved; the irreversible capacity loss is reduced; lithium nitrate provides a large number of lithium ions, so that the Li < + > transference number is increased; the generated SEI film has stable ionic conductivity, and the irreversible capacity of first charging is reduced; the diffusion requirement of lithium ions can be met while the integrity and uniformity of the SEI film generated by the material are ensured; and the cyclic discharge capacity of the battery is improved.

Description

technical field [0001] The invention belongs to the field of preparation of lithium ion battery materials, in particular to a mixed lithium salt electrolyte. Background technique [0002] Lithium-ion batteries are widely used in various fields of national economic production due to their outstanding advantages such as high working voltage, large specific energy, long cycle life, no memory effect, small self-discharge, high safety, and relatively low pollution. Since the beginning of the 21st century, with the emergence of emerging industrial products such as smartphones, tablet computers, and electric vehicles, their demand has shown explosive growth. Therefore, the improvement and improvement of the performance of lithium-ion batteries has become a research hotspot that the scientific community continues to pay attention to. Lithium-ion batteries are usually composed of shell materials, positive and negative electrodes, separators, and electrolytes. The electrolyte has a v...

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Problems solved by technology

However, its excessive water sensitivity, low thermal stability, and excessive resistance of the SEI film formed at low temperature also limit its application to a certain extent.

Problems such as lithium dendrite growth and poor water sensitivity in existing electrolyte materials seriously affect the safety and stability of lithium-ion batteries. The growth of lithium dendrites will destroy the integrity of the formed solid electrolyte interface (SEI) film. The cycle discharge capacity of the battery is reduced, which affects the performance of the battery

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