Lithium transition metal composite oxide as a positive electrode active material for rechargeable lithium secondary batteries

A powderous positive electrode material for lithium ion batteries, comprising crystalline lithium transition metal-based oxide particles having a general formula Li1+a((Niz (Ni0.5Mn0.5)y Cox)1−k Ak)1−aO2, wherein A is a dopant, −0.030≤a≤0.025, 0.10≤x≤0.40, 0.25≤z≤0.52, x+y+z=1 and k≤0.01, wherein the crystalline powder has a crystallite size less than 33 nm as determined by the Scherrer equation based on the peak of the (104) plane obtained from the X-ray diffraction pattern using a CuKα radiation source, and wherein MR(SC—Ni) is between 1.04 and 1.10, MR(SC—Ni) being a normalized molar ratio MR(Ni) of a particle, wherein EDS analysis is performed at sample locations having the same volume and being located along an EDS scan line crossing a center of the particle on a cross-section of the particle, wherein a first sample location (D1) is at a surface of a first particle edge, a second sample location (D3) is at a center of the particle, and a third sample location (D5) is at a surface of a second particle edge, opposite the first particle edge, and wherein MR(SC—Ni) is obtained by dividing the sum of the value of MR(Ni) measured in a volume at the first sample location and the value of MR(Ni) measured in a volume at the third sample location, by two times the value of MR(Ni) measured in a volume at the second sample location.