Morphological, electrochemical and in-situ XRD study of LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ as high potential cathode material for rechargeable lithium-ion batteries

By using a simple high temperature solid state reaction, LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ is prepared via Ni site dual substitution with Mn and Al. Structural observation reveals that the as-prepared sample can be indexed to an α-NaFeO₂ type single phase with R-3m space group. Morphology and particle size investigations present that Mn and Al co-doped LiNi_0.8Co_0.2O₂ is composed of micro-sized secondary particles (5–20 μm) agglomerated from highly packed primary particles (1–2 μm). Charge–discharge tests demonstrate that LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ can reversibly react with lithium between 2.5 and 4.9 V with a high discharge capacity of 202.0 mAh g⁻¹. This favorable electrochemical performance is attributed to the stable crystal structure after Mn and Al dual doping. This quasi-reversible structural change is also proved by in-situ X-ray diffraction study in this work. - Highlights: • LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ is prepared via Ni site dual substitution with Mn and Al. • LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ shows high reversibility as high potential cathode. • Structural evolution of LiNi_0.6Co_0.2Mn_0.1Al_0.1O₂ is studied in 2.5–4.9 V. • In-situ X-ray diffraction shows the quasi-reversible structural change.