High-voltage lithium cobalt oxide material and preparation method thereof, positive plate and secondary battery

The invention belongs to the technical field of secondary batteries, and particularly relates to a preparation method of high-voltage lithium cobalt oxide, which comprises the following steps: step S1, adding a cobalt source, terephthalic acid, cobalt trichloride, lithium fluoride and deionized water into a polytetrafluoroethylene container, heating for crystallization, washing to obtain an intermediate product, drying the intermediate product, heating for primary calcination, and drying to obtain the high-voltage lithium cobalt oxide. Heating and carrying out secondary calcination to obtain a spindle cobaltosic oxide precursor; s2, adding a carbon source into a solvent, adding alcohol and the spindle cobaltosic oxide precursor, carrying out a heating reaction, cooling to room temperature, and filtering to obtain a precipitate; and S3, adding the precipitate into a metal cation salt solution, heating, stirring, drying, and calcining at high temperature to obtain the high-voltage lithium cobalt oxide. The prep