The first cycle characteristics of Li[Ni1/3Co1/3Mn1/3]O2 charged up to 4.7 V

In this research, we studied the first cycle characteristics of Li[Ni1/3Co1/3Mn1/3]O-2 charged up to 4.7 V. Properties, such as valence state of the transition metals and crystallographic features, were analyzed by X-ray absorption spectroscopy and X-ray and neutron diffractions. Especially, two plateaus observed around 3.75 and 4.54 V were investigated by ex situ X-ray absorption spectroscopy. XANES studies showed that the oxidation states of transition metals in Li[Ni1/3Co1/3Mn1/3]O-2 are mostly Ni2+, Co3+ and Mn4+. Based on neutron diffraction Rietveld analysis, there is about 6% of all nickel divalent (Ni2+) ions mixed with lithium ions (cation mixing). Meanwhile, it was found that the oxidation reaction of Ni2+/Ni4+ is related to the lower plateau around 3.75 V, but that of Co3+/Co4+ seems to occur entire range of x in Li1-x[Ni1/3Co1/3Mn1/3]O-2. Small volume change during cycling was attributed to the opposite variation of lattice parameter c and a with charging-discharging. (C) 2003 Elsevier Ltd. All rights reserved.