Synthesis and electrochemical properties of sulfur doped-Li_xMnO_2-yS_y materials for lithium secondary batteries

Sulfur doped lithium manganese oxides (Li_xMnO_2-yS_y) were prepared by ion exchange of sodium for lithium in Na_xMnO_2-yS_y precursors obtained by a sol-gel method. These materials had the nano-crystallite size, which was composed of grain size of about 100-200 nm. Especially, Li_0.56MnO_1.98S_0.02 delivered the initial discharge capacity of 170 mAh g^-1 and gradually increased the discharge capacity of 220 mAh g^-1 until 50 cycles. Moreover, it showed an excellent cycling behavior, although its original structure transformed into the spinel phase during cycling.