1. A positive electrode active material powder suitable 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 particles comprising the elements: Li, M′ and oxygen, wherein M′ has a formula: M′=NizMnyCoxAk, wherein A is a dopant, 0.60≤z≤0.89, 0.05≤y≤0.20, 0.05≤x≤0.20, x+y+z+k=1, and k≤0.01, said positive electrode active material powder having a median particle size D50 ranging from 5 μm to 15 μm, a span ranging from 0.25 to 0.90, and a surface layer thickness ranging from 10 nm to 200 nm, said surface layer comprising: sulfur in a content superior or equal to 0.150 wt % and inferior or equal to 0.375 wt % with respect to the total weight of the positive electrode active material powder, and aluminum in a content superior or equal to 0.05 wt % and inferior or equal to 0.15 wt % with respect to the total weight of the positive electrode active material powder,