A positive electrode active material powder for lithium-ion batteries, comprising lithium transition metal-based oxide particles, said particles comprising a core and a surface layer, said surface layer being on top of said core, said particle comprising the elements: Li, M' and oxygen, wherein M' has a formula: M'=Ni z Mn y Co x A k , wherein A is a dopant, 0.80≤z≤0.90, 0.05≤y≤0.20, 0.05≤x≤0.20, x+y+z+k=1, and 0≤k≤0.01, said positive electrode active material powder having a median particle size D50 ranging from 5μm to 15μm and a surface layer thickness ranging from 10nm to 200nm, said surface layer comprising sulfate ion (SO42) in a content superior or equal to 6.78 · z - 4.83 wt% and inferior or equal to 6.78 · z - 4.33 wt% with respect to the total weight of the positive electrode active material, wherein the thickness of the surface layer corresponds to a minimal distance D defined as: D in nm = L S 1 − L S 2 , wherein L S1 is a first point location at the center of a particle, L S2 is a second point location in a line defined between said first point location and a geometric center of said particle, wherein a content of S measured by TEM-EDS at the second point location L S2 is superior or equal to 0at% and inferior or equal to 5.0% of a content of S measured at the first point location, said second content of S (S 2 ) being defined as: S 2 in at % = S 3 ± 0.1 at % , S 3 being a content of S (in at%) at a third point location ( LS 3 ) in said line, said third point being located at any location between the geometric center of said particle and the second point location L S2 , wherein the median particle size D50 is measured according to the method in the description under the heading 'D) PSD measurement'. Li, M' and oxygen, wherein M' has a formula: M'=Ni z Mn y Co x A k , wherein A is a dopant, 0.80≤z≤0.90, 0.05≤y≤0.20, 0.05≤x≤0.20, x+y+z+k=1, and 0≤k≤0.01, said positive electrode active material powder having a median particle size D50 ranging from 5μm to 15μm and a surface layer thickness ranging from 10nm to 200nm, said surface layer comprising sulfate ion (SO42) in a content superior or equal to 6.78 · z - 4.83 wt% and inferior or equal to 6.78 · z - 4.33 wt% with respect to the total weight of the positive electrode active material, wherein the thickness of the surface layer corresponds to a minimal distance D defined as: D in nm = L S 1 − L S 2 , wherein L S1 is a first point location at the center of a particle, L S2 is a second point location in a line defined between said first point location and a geometric center of said particle, wherein a content of S measured by TEM-EDS at the second point location L S2 is superior or equal to 0at% and inferior or equal to 5.0% of a content of S measured at the first point location, said second content of S (S 2 ) being defined as: S 2 in at % = S 3 ± 0.1 at % , S 3 being a content of S (in at%) at a third point location ( LS 3 ) in said line, said third point being located at any location between the geometric center of said particle and the second point location L S2 , wherein the median particle size D50 is measured according to the method in the description under the heading 'D) PSD measurement'. <EOS>