High-nickel positive electrode active material, preparation method thereof, and lithium-ion battery, battery module, battery pack and power consuming device comprising same
The present application provides a high-nickel ternary positive electrode active material, which comprises a core Li 1+a [LixCoyMn z M b ]O 2 , a fast ionic conductor Li α Al X Si Y O 4 of a first shell layer, an oxide of an element R of a second shell layer, and a transition layer Li p R q O w formed between the first shell layer and the second shell layer. In the high-nickel ternary positive electrode active material of the present application, the surface impurity lithium amount is significantly reduced, and by creatively converting the surface impurity lithium into effective components in the fast ionic conductors Li α Al X Si Y O 4 and Li p R q O w which accelerate the intercalation/deintercalation of lithium ions in the core material, the decomposition and gas production of an electrolyte solution caused by the surface impurity lithium is greatly improved, such that a high-nickel ternary lithium-ion battery has high energy density as well as good cycle performance and safety performance.
1 . A high-nickel positive electrode active material with a core-shell structure, wherein
the core comprises Li 1+a [Ni x Co y Mn z M b ]O 2 , wherein 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M being Sb;
the shell comprises a first shell layer coating the core, a second shell layer coating the first shell layer, and a transition layer formed between the first shell layer and the second shell layer; wherein
the first shell layer is a fast ionic conductor consisting of four elements of lithium, aluminum, silicon and oxygen;
the second shell layer comprises an oxide of an element R, the element R being selected from at least one of B, Ti, P, or La; and
the transition layer comprises LiBO 2 .
2 . The high-nickel positive electrode active material according to claim 1 , wherein
the fast ionic conductor of the first shell layer is Li α Al X Si Y O 4 , wherein 0<X<2.4, 0<Y<1.8, 0.8≤α≤1.2, and a ratio of the stoichiometric coefficient X of the element aluminum to the stoichiometric coefficient Y of the element silicon is 0.8 to 1.2.
3 . The high-nickel positive electrode active material according to claim 1 , wherein
the x is 0.8≤x<1.
4 . The high-nickel positive electrode active material according to claim 1 , wherein
a mass ratio of the element lithium in the core to the element lithium in the shell is (40 to 1,300):1.
5 . The high-nickel positive electrode active material according to claim 1 , wherein
based on a total mass of the high-nickel positive electrode active material, a mass content of the element M in the high-nickel positive electrode active material is 1,000 to 5,000 ppm.
6 . The high-nickel positive electrode active material according to claim 1 , wherein
based on a total mass of the high-nickel positive electrode active material, a mass content of the element R in the second shell layer is 100 to 20,000 ppm.
7 . The high-nickel positive electrode active material according to claim 1 , wherein
in the high-nickel positive electrode active material, a mass ratio of the element Si to the element R in the second shell layer is 0.1 to 7.0:1.
8 . The high-nickel positive electrode active material according to claim 1 , wherein
based on a total mass of the high-nickel positive electrode active material, a total mass content of the elements silicon and aluminum in the first shell layer is 435 to 13,150 ppm.
9 . The high-nickel positive electrode active material according to claim 1 , wherein a volume-average particle size Dv50 of the high-nickel positive electrode active material is 1.5 to 20 μm, and a total thickness of the shell is 0.001 to 1 μm.
10 . A method for preparing a high-nickel positive electrode active material, comprising:
coating a high-nickel ternary precursor with a silicon-aluminum hydroxide to obtain a first intermediate;
mixing and sintering the first intermediate and an M precursor and a lithium precursor to obtain a second intermediate; and
mixing and sintering the second intermediate and an R precursor to obtain the high-nickel positive electrode active material;
wherein the high-nickel positive electrode active material is a core-shell structure,
the core comprises Li 1+a [Ni x Co y Mn z M b ]O 2 , wherein 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M being Sb;
the shell comprises a first shell layer coating the core, a second shell layer coating the first shell layer, and a transition layer formed between the first shell layer and the second shell layer; wherein
the first shell layer is a fast ionic conductor consisting of four elements of lithium, aluminum, silicon and oxygen; and
the second shell layer comprises an oxide of an element R, the element R being selected from at least one of B, Ti, P, or La; and
the transition layer comprises LiBO 2 .
11 . The preparation method according to claim 10 , wherein
a process of coating the high-nickel ternary precursor with a silicon-aluminum hydroxide comprises:
dissolving an aluminum precursor and a silicon precursor in an alkaline solution, and then adding a high-nickel ternary precursor to obtain a solid-liquid mixture; and
lowering the pH of the solid-liquid mixture to initiate a hydrolysis-in-situ precipitation reaction between the aluminum precursor and the silicon precursor, to obtain a high-nickel ternary precursor coated with a silicon-aluminum hydroxide.
12 . A lithium-ion battery, comprising a high-nickel positive electrode active material according to claim 1 .
13 . A battery module, comprising the lithium-ion battery according to claim 12 .
14 . A high-nickel positive electrode active material with a core-shell structure, wherein
the core comprises Li 1+a [Ni x Co y Mn z M b ]O 2 , wherein 0.6≤x<1, 0<y<0.3, 0<z<0.3, 0<a<0.2, 0<b<0.2, x+y+z+b=1, M being Sb;
the shell comprises a first shell layer coating the core, a second shell layer coating the first shell layer, and a transition layer formed between the first shell layer and the second shell layer; wherein
the first shell layer is a fast ionic conductor consisting of four elements of lithium, aluminum, silicon and oxygen;
the second shell layer comprises an oxide of an element R and a hydroxide Co(OH) 2 , the element R being Co; and
the transition layer comprises LiBO 2 .