Single-crystal cathode material modified by molten salt-assisted valence gradient doping, preparation method therefor, and use thereof

A preparation method for a single-crystal cathode material modified by molten salt-assisted valence gradient doping, comprising the following steps:

• (1) mixing a transition metal source, a lithium source, a manganese source, and a molten salt additive, sequentially performing first sintering and second sintering, and removing the molten salt additive to obtain a doped and modified single-crystal cathode material precursor;
• and
• (2) tempering the doped and modified single-crystal cathode material precursor to obtain the single-crystal cathode material modified by molten salt-assisted valence gradient doping;
• wherein the transition metal source in the step (1) is a transition metal oxide containing one or more doping elements of Ti4+, Nb5+, and Mo6+;
• or the transition metal source in the step (1) is a transition metal oxide containing one or more doping elements of Mg2+ and Sm3+;
• the manganese source comprises MnCO3, Mn3O4, or MnO2;
• in the step (1), a molar ratio of the transition metal source, the lithium source, the manganese source, and the molten salt additive is 0.01:(1-1.08):2:(1-2);
• in the step (1), the mixing is ball milling;
• the ball milling is performed for 3-6 h at a rotation speed of 300-400 r/min, and a ball-to-material ratio is 10-20:1;
• and
• in the step (2), the tempering is performed at a temperature of 700-750 °C for 4-6 h, and a rate of heating to the temperature required for the tempering is 1.5-3 °C/min.