Lithium-ion battery positive electrode lithium supplement additive, preparation method therefor, and lithium-ion battery

A preparation method for a lithium-ion battery positive electrode lithium supplement additive, comprising:

• step 1:
• preparing a composite lithium salt
• a lithium raw material is heated from the room temperature to 400-950° C. at a heating rate of 1-10° C./min under a vacuum degree of less than 100 pa, held at the temperature for 15-480 min, naturally cooled to the room temperature with the vacuum degree in the furnace kept, then taken out and crushed, so as to obtain the composite lithium salt xLiOH·yLi2O·zLi2CO3·wH2O, wherein x, y and z are mass proportion, 0<x<0.5, 0.5≤y<1.0, 0<z<0.5, x+y+z=1, w represents a crystal water content, and 0≤w≤1;
• the lithium raw material is at least one of a lithium hydroxide-lithium oxide-lithium carbonate composite, a lithium hydroxide-lithium oxide-lithium oxalate composite, a lithium hydroxide-lithium peroxide-lithium carbonate composite, a lithium hydroxide-lithium peroxide-lithium oxalate composite, a lithium hydride-lithium oxide-lithium carbonate composite, a lithium hydride-lithium oxide-lithium oxalate composite, a lithium hydride-lithium peroxide-lithium carbonate composite, and a lithium hydride-lithium peroxide-lithium oxalate composite;
• step 2:
• mixing the composite lithium salt with a nickel source
• the composite lithium salt is mixed with the nickel source at a rotation speed of 500-1000 rpm with a lithium source-nickel source molar ratio of 1.5-2.2:1.0 for 0.5-6.0 h under an argon or nitrogen protective atmosphere, so as to obtain a mixed powder of the composite lithium salt and the nickel source;
• the nickel source is at least one of nickelous oxide, dinickel trioxide, nickel dioxide, nickel hydroxide, nickel oxide hydroxide, nickel carbonate, nickel oxalate and nickel acetate;
• step 3:
• sintering
• under a protective atmosphere or an oxidizing atmosphere, the mixed powder of the composite lithium salt and the nickel source is heated to 100-300° C. at a heating rate of 1-10° C./min, held at the temperature for 0.5-5.0 h, then heated to 600-800° C. at a heating rate of 1-10° C./min, held at the temperature for 5.0-20.0 h, and naturally cooled to the room temperature in the furnace, so as to obtain a sintered material;
• step 4:
• crushing
• the sintered material is crushed at a rotation speed of 800-1000 rpm for 15-30 min under an argon or nitrogen protective atmosphere, pulverized, and sieved by a 350-400 mesh screen, so as to obtain the lithium-ion battery positive electrode lithium supplement additive.