In-situ generated electrolyte additive as well as preparation method and application thereof

The invention relates to an in-situ generated electrolyte additive and a preparation method and application thereof. The additive is a Lewis acid-base complex multifunctional additive. The Lewis acid-base complex multifunctional additive is prepared by adding Lewis acid and Lewis base into a conventional electrolyte and then carrying out Lewis acid-base coordination reaction between the Lewis acid and the Lewis base. The additive can be generated in the electrolyte in situ, and has multiple functions of widening an electrochemical window of the electrolyte, retarding flame, inhibiting decomposition and hydrolysis of electrolyte salt, removing harmful impurities in the electrolyte, stabilizing an electrode material and an electrolyte interface and the like. The obtained multifunctional electrolyte containing the additive can be used for improving the working voltage, the energy density, the power density, the cycle life and the safety of an electrochemical energy storage device, and is easy to popularize and a