Study of the nanosized Li₂MnO₃: Electrochemical behavior, structure, magnetic properties, and vibrational modes

In this work, we synthesized nano-particles (20-80 nm) of Li ₂MnO₃ using the self-combustion reaction and studied the electrochemical activity of electrodes prepared from this nano-material at 30, 45, and 60 C. It was shown that the first Li-extraction from nano-Li ₂MnO₃ occurs at much lower potentials (by 180-360 mV) in comparison with micron-sized Li₂MnO₃ electrodes. This can be associated with the higher surface-to-volume ratio, much shorter the diffusion path and the increased surface concentration of the electrochemically active sites. On the basis of magnetic susceptibility studies of nano-Li ₂MnO₃ we proposed a model of disordered surface layer, containing Mn³⁺ or Mn²⁺ ions, both at low spin state, at the surface of these nano-particles. From the results of structural analysis (by X-ray and electron diffraction and vibrational Raman spectroscopy) of galvanostatically cycled nano-Li₂MnO₃ electrodes in Li-cells we came to a conclusion of partial transition of layered LiMO ₂ to spinel-type ordering.