The invention discloses a preparation method of an ultrahigh 
nickel single crystal positive 
electrode material, which comprises the following steps of S1, mixing a ternary precursor and 
lithium hydroxide according to a 
lithium-
metal molar ratio of 1.01-1.10: 1, adding a 
doping agent, and calcining in an 
oxygen atmosphere to obtain a primary calcined material, S2, performing coarse crushing, fine crushing, sieving and demagnetizing on the primary calcined material to obtain a crushed material, S3, adding the crushed material and water into a reaction kettle according to a water-material ratio of 0.5: 1-5: 1, controlling the temperature of the reaction kettle, adding a 
reagent for reaction, and 
drying after the reaction is finished to obtain a mixed material, and S4, mixing the mixture witha modified 
coating agent, placing the mixture in an 
atmosphere furnace for secondary 
calcination, and then performing coarse crushing, fine crushing, sieving and demagnetizing to obtain the ternary positive 
electrode material. The ultrahigh 
nickel single crystal is subjected to optimization treatment by different calcining processes and is coated and modified by the modified 
coating agent, so thatthe obtained 
single crystal positive 
electrode material has the characteristics of extremely low residual alkali level and less single 
crystal particle agglomeration state, and the soft 
package battery assembled by the single 
crystal material has the characteristics of good 
thermal stability, low 
gas expansion rate and excellent cycle performance; compared with a conventional high-
nickel secondary ball with the same 
nickel content, the material has obvious performance advantages.