MnO powder as anode active materials for lithium ion batteries

摘要

MnO powder materials are investigated as anode active materials for Li-ion batteries. Lithium is stored reversibly in MnO through conversion reaction and interfacial charging mechanism, according to the results of ex situ XRD, TEM and galvanostatic intermittent titration technique. A layer of the solid electrolyte interphase with a thickness of 20-60 nm is covered on MnO particles after full insertion. MnO powder materials show reversible capacity of 650mAh g~(-1) with average charging voltage of 1.2 V. It can deliver 400 mAh g~(-1) at a rate of 400 mA g~(-1). The cyclic performance of MnO is improved significantly after decreasing particle size and coating with a layer of carbon. Among observed transition metal oxides, MnO shows relatively lower voltage hysteresis (< 0.7 V) between the discharging and the charging curves at 0.05 C. In addition to its environmental benign feature and high density (5.43 g cm~(-3)), MnO seems a promising high capacity anode material for Li-ion batteries among transition metal oxides. However, the initial columbic efficiency is less than 65% and the voltage hysteresis is still too high. The origins of them are discussed.