Layered O2-Li 2/3(Ni 1/3−xMn 2/3−xM 2x)O 2 (M=Cr, Co, x=0.05) cathode materials for Li-ion rechargeable batteries

Abstract

Layered O2-phase lithium manganese oxides, Li 2/3(Ni 1/3−xMn 2/3−xM 2x)O 2 (M=Cr, Co, x=0.05) were prepared by ion exchange of Li for Na in P2-Na 2/3(Ni 1/3−xMn 2/3−xM 2x)O 2 precursors, which were synthesized by a citric acid-assisted sol–gel method. The as-synthesized compounds were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and galvanostatic tests. The discharge capacity of O2-Li 2/3(Ni 1/3−xMn 2/3−xCo 2x)O 2 ( x=0.05) is around 188 mA h g −1 (vs. Li metal; voltage window 2.5–4.6 V) at a current density of 0.2 mA cm −2.