Nickel-cobalt-manganese multi-element lithium ion battery cathode material with dopants and its methods of preparation

A method of preparing a nickel-cobalt-manganese multi-element lithium ion battery cathode material, comprising the steps of:

• (1) preparing a nickel-cobalt-manganese multi-element intermediate, comprising:
• dissolving salts of nickel, cobalt, and manganese in water to obtain an aqueous solution;
• adding one or more salts selected from the group consisting of a molybdenum salt, a chromium salt, a germanium salt, an indium salt, a strontium salt, a tantalum salt, a magnesium salt, and a salt of a rare earth element to the aqueous solution;
• stirring the solution to dissolve the salts,
• wherein the resulting solution has a total molar concentration of metal elements of 0.8-1.3 mol/L, and a molar ratio of Ni:Co:Mn=(1.89-3.06):(1.5-2.1):(1-1.2), wherein a total mass percentage of molybdenum, chromium, germanium, indium, strontium, tantalum, magnesium or rare earth elements is 0.11%-0.3% of a total mass of nickel, cobalt, and manganese,
• adding the above-described metal salt solution at a speed of 5-30 mL/min at a temperature in the range of 40° C. to 70° C. into an alkaline solution having polyethylene glycol, NaOH, and NH3, or into an oxalate solution having polyethylene glycol to obtain a reaction solution;
• stirring the reaction solution for 1-2 h, then letting stand for 1-4 h;
• filtering the reaction solution to obtain a solid;
• washing the solid with deionized water to obtain a solid having a mass percentage of alkali metal in the solid of less than 0.01%;
• drying the solids after washing at 105° C.-120° C. for 3-5 h to obtain the nickel-cobalt-manganese multiple-element intermediate;
• (2) mixing the multi-element nickel-cobalt-manganese intermediate with a lithium salt uniformly according to a ratio of Li:(Ni+Co+Mn)=1.05-1.1:1 to obtain a first mixture;
• grinding the first mixture for 2-8 h,
• pre-treating the grinded for 2 h at 500° C.-550° C.;
• adding polyvinyl alcohol into the pre-treated material, mixing evenly, and pressing the resulting mixture into lumps, wherein the mass percentage of the added polyvinyl alcohol is 0.98%-2% of the total mass of nickel, cobalt, and manganese;
• (3) placing the material in lumps into a furnace, calcining the material in lumps at 800° C.-950° C. for 15-23 h, removing said material from the furnace, cooling it to 45° C.−5° C., crushing said material and passing it through a 400 mesh sieve;
• (4) calcining the material that passes through a 400 mesh sieve at 700° C.-820° C. for 6-8 h, removing from the furnace, cooling to 45° C.-55° C., crushing the material, passing it through a 400 mesh sieve,
• wherein the material obtained in step (4) comprises non-agglomerated single-grain particles and has a compact density of 3.5-3.7 g/cm3, the particles has a diameter of 0.6-30 μm and a chemical formula of LiNixCoyMnzM(1-x-y-z)O2 wherein M is one or more of molybdenum, chromium, germanium, indium, strontium, tantalum, magnesium, or rare earth elements, the values of x, y, z are:
• 0.37≦x≦0.55, 0.27≦y≦0.35, 0.17<z<0.22, a content of M is 0.11%-0.3% of a total mass of nickel, cobalt, and manganese.