Activation of Manganese Ions in Lithium-ion Battery Anode Materials via Nickel and Cobalt Doping

Nanosized Ni_xMn_3?xO_z(x?=?0, 0.25, 0.50, 0.65, 0.75 and 1.0) and (1?y)Li₂MnO₃???(y)LiCoO₂ (y?=?0, 0.1, 0.25, 0.50 and 1.0) powders were synthesized by the Pechini process and electrochemically evaluated as battery anode materials for their lithium capacities and cycle life. The materials were investigated using x-ray diffraction (XRD), a scanning electron microscope (SEM) and electrochemical characterizations. Undoped anode materials (i.e., Mn₂O₃ when x?=?0 and Li₂MnO₃ when y?=?0) had the lowest first cycle Coulombic efficiencies and long-term cycling capacities. However, upon addition of Ni or Co elements, drastic improvements in battery performance was observed. The highest percentages of increase in first cycle performance were observed at an intermediate level of doping (i.e., x?=?0.25 or 0.50 and y?=?0.1 or 0.25). For extended cycling, on the other hand, anode materials with higher levels of nickel and cobalt doping are the best.