The above precursor of the nickel cobalt manganese active materials, lithium hydroxide as the lithium source, aluminum oxide as the first dopant, tungsten oxide as the second dopant, and strontium carbonate as the third dopant were mixed at a molar ratio of 0.99:1.03:0.007:0.002:0.001 in a mixer. The mixture was subjected to the programmed calcining in a furnace. While oxygen was introduced at a flow rate of 1.33 m³/kg-h, the mixture was heated at a constant rate for 3 hours from room temperature to 300° C. and kept at a temperature of 300° C. for 2 hours, to complete the first calcining. And then, the mixture was heated at a constant rate for 6 hours to 780° C., and kept at 780° C. for 12 hours, to complete the second calcining. Finally, the mixture was naturally cooled to room temperature, to obtain a doped nickel cobalt manganese active material. The doped nickel cobalt manganese active material was subjected to cooling, pulverizing and sieving, then ready for use.

(3) The Preparation of a Positive Electrode Material.

The doped nickel cobalt manganese active material and boric acid as the coating agent were mixed in a molar ratio of 1:0.01 in a high-speed mixer. The mixture was subjected to a third calcining in a furnace, at 350° C. for 10 hours, to obtain the positive electrode material P1, which had a formula of Li_1.03(Ni_0.896Co_0.057Mn_0.037Al_0.007Zr_0.002Sr_0.001)O₂/B₂O₃. The positive electrode material P1 was subjected to cooling, sieving and removing iron impurities, then ready for use.

As mentioned above, the obtained positive electrode material P1 was subjected to extreme water washing and testing for its intrinsic specific surface area and intrinsic pore size. The results were listed in Table 1-2.