The invention provides an
electrolyte, a preparation method thereof and a battery. The
electrolyte comprises a
phosphate flame retardant, a cosolvent, a high-donor-number
solvent and salt, the cosolvent comprises at least one of a
fluorobenzene compound, a fluoroether compound or a
nitrile compound, the donor number of the high-donor-number
solvent is larger than or equal to 8 kcal / mol, and the salt is
sodium salt or
lithium salt. The
phosphate flame retardant is added, so that the safety of the battery can be improved; a cosolvent which is weakly coordinated with
metal cations in salt is introduced into an
electrolyte, the cosolvent and a
phosphate flame retardant generate
dipole-
dipole interaction with the phosphate flame retardant due to low polarity and strong
dipole moment, a phosphate flame retardant
solvent can be pulled outwards, the
binding energy between the phosphate flame retardant and the
metal cations is weakened, a
desolvation energy barrier is reduced, and the
desolvation performance of the phosphate flame retardant is improved. The rate capability of the battery is improved; the anions in the high-donor-number solvent and the salt are preferentially coordinated with the
metal cations, so that the coordination ratio of the phosphate to the metal cations can be reduced, and the rate capability of the battery can be improved.