Negative electrode film-forming functional electrolyte, preparation method thereof and lithium metal battery

The invention belongs to the technical field of electrolytes, and discloses a negative electrode film-forming functional electrolyte and a preparation method thereof. The negative electrode film-forming functional electrolyte comprises an additive, an ether solvent and a lithium salt, and the additive is one or more of compounds with a structure as shown in a formula (I); formula I; wherein R1 and R2 are respectively and independently selected from alkyl and alkoxy with the carbon atom number of 16 to 24; and R3 and R4 are respectively and independently selected from alkyl and alkoxy with the carbon atom number of 1-8. On one hand, the additive forms LiF-rich SEI on the surface of the negative electrode through decomposition, on the other hand, large-size cations occupy the surface of the negative electrode preferentially compared with Li < + > under the electrostatic adsorption effect, the effect of promoting uniform deposition of Li < + > is achieved, and under the synergistic effect of the positive ions an