Electrolyte and preparation method thereof and lithium ion battery

Abstract

An electrolyte and a preparation method thereof and a lithium ion battery, where the electrolyte comprises the following components in percentages by mass: 10-20% of a lithium salt, 0.2-7% of an additive composition and a balance of a solvent; among them, the additive composition comprises a boron-containing lithium salt compound and a sulfur-based compound represented by Formula 1, in which Rand Rare each independently selected from hydrogen, halogen, or substituted or unsubstituted alkyl; Ris selected from a substituted or unsubstituted alkylene, or is a direct bond; the boron-containing lithium salt compound is at least 0.1% by mass of the electrolyte. The electrolyte can significantly improve the performance of an SEI film, thereby facilitating increasing the cycle performance and storage performance of the lithium ion battery.