Scalable synthesis and electrochemical investigations of fluorine-doped lithium manganese spinel oxide

A scalable synthesis route for the preparation of fluorine-doped lithium manganese spinel was developed. The effect of 2.5% fluorine doping on the properties of aluminum-doped lithium manganese spinel was investigated by examining the electrochemical performance and structural changes. The electrochemical study indicates that the initial discharge capacity increases by about 5% while other properties, like the capacity retention and rate performance, remain almost unchanged. The structural studies indicate that no impurity phase was formed, along with only little morphological changes and a slight increase in the lattice parameter. The Mn K-edge absorption spectra clearly show that the average manganese oxidation state decreases as a result of fluorine doping and Mn L_II,III -edge spectra indicate that the electronic structure of the fluorine-doped spinel changes significantly, which may alleviate the intrinsic structural instability of this material.