Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells

Niobium triselenide offers promise as a high energy density cathode material for ambient temperature lithium rechargeable cells. The electrochemical behavior of NbSe3 in the battery electrolyte, i.e., 1.5m LiAsF6/2 Me-THF is reported here. A detailed study has been carried out using various ac and dc electrochemical techniques to establish the mechanism of intercalation of three equivalents of Li with NbSe3 as well as the rate governing processes in the reduction of NbSe3. Based on the experimental data, an equivalent circuit has been formulated to represent the NbSe3-solution interface. The kinetic parameters for the reduction of NbSe3 were evaluated from the ac and dc measurements. Finally, the structural change in NbSe3 on lithiation during initial discharge which results in higher cell voltages and different electrochemical response as compared to virgin NbSe3 was identified to be a loss of crystallographic order, i.e., amorphous by x-ray diffraction