The structure, morphology, and electrochemical properties of Li1+xNi1/6Co1/6Mn4/6O2.25+x/2 (0.1 ≤ x ≤ 0.7) cathode materials

Li1+xNi1/6Co1/6Mn4/6O2.25+x/2 (0.1 ≤ x ≤ 0.7) cathode materials have been synthesized by a simple carbonate co-precipitation method. The effects of the lithium content on the structure, physical property, and electrochemical performance of the samples have been investigated. As the increase of lithium content, the Li1+xNi1/6Co1/6Mn4/6O2.25+x/2 evolves from a mixture of hexagonal R−3m, monoclinic C2/m, and spinel Fd−3m structure to a mixture of hexagonal and monoclinic structure, accompanied with less cation mixing between Li+ and Ni2+. The increase of x value also affects the size of the primary particles and the roughness of the secondary particles. The Li1+xNi1/6Co1/6Mn4/6O2.25+x/2 with appropriate lithium content, e.g., x = 0.3, thereby small particle size, high pellet density, and low cation mixing, brings on the largest discharge capacity, which is more than 288 mAh g−1 in the voltage range of 2.0–4.8 V at 25 mA g−1, and the lowest irreversible capacity loss of 47 mAh g−1 among these cathode materials.

► A simple co-precipitation method is used to prepare spherical Ni1/6Co1/6Mn4/6CO3.
► The effect of Li content on the physical and electrochemical properties is studied.
► Li1.3Ni1/6Co1/6Mn4/6O2.4 exhibits excellent physical and electrochemical properties.