The invention discloses an
electrolyte additive for a
lithium or
sodium ion battery and an application thereof, belonging to the technical field of
lithium batteries; the
electrolyte additive comprises g-C3N4 and a film-forming additive, and the g-C3N4 and the film-forming additive are coupled to form a negative
electrode solid electrolyte interface film through intermolecular
hydrogen bonding; the film-forming additive comprises one or more organic substances containing a carbonyl bond, an
ether bond, a hydroxyl group, a carboxyl group, an amino group, a
nitrile group, a
thiol group, a
sulfonic acid group, a
hydrocarbon oxygen carbonyl group, a haloformyl group, a carbamoyl group, a
formyl group, an
amide group, and a
halogen; in terms of
mass fractions, the content of g-C3N4 accounts for 0.001%-5% of the total electrolyte
mass, and the content of the film-forming additive accounts for 0.01%-30% of the total electrolyte
mass. The present invention uses g-C3N4 with strong nucleophilic ability and a film-forming additive for
coupling. During the electrochemical reaction, a negative
electrode solid electrolyte interface film rich in
nitrogen and with good
conductivity is formed. The film can inhibit the generation of
lithium /
sodium dendrites, achieve uniform deposition of lithium /
sodium, and improve the rate and cycle performance of the battery.