Non-aqueous electrolyte and preparation method thereof, and secondary battery and electric apparatus containing same

Provided are a non-aqueous electrolyte and a preparation method thereof, and a secondary battery and an electric apparatus containing the same. The non-aqueous electrolyte contains a non-aqueous solvent and lithium ions, first cations, and first anions dissolved therein, where the first cation is a metal cation Me n+ other than the lithium ion, n representing a chemical valence of the metal cation; the first anion is a difluorooxalate borate anion DFOB ; mass concentration of the first cations in the non-aqueous electrolyte is D1 ppm, and mass concentration of the first anions in the non-aqueous electrolyte is D2 ppm, both based on total mass of the non-aqueous electrolyte; and the non-aqueous electrolyte satisfies that D1 is 0.5 to 870 and that D1/D2 is 0.02 to 2. The non-aqueous electrolyte in this application enables the secondary battery to have good cycling performance, safety performance, and kinetic performance.