Structurally connected Vanadates and Molybdates as Electrode materials

This book presents the Electrochemical performance of three structurally related compounds MVMoO7 (M= Fe3+, Cr3+, Al3+) as electrode materials for Li-ion batteries. It is observed that the voltage corresponding to the redox couples V5+/V4+ and Mo6+/Mo5+ are significantly different for AlVMoO7 vis-à-vis the Fe and Cr analogues. This study provides conclusive evidence that the presence of different counter cations in the lattice (trivalent ions in the present case) does affect the energetics of the redox process of the electrochemically active species. FeVMoO7, CrVMoO7 and AlVMoO7 react with 3.5 Li, 2.5 Li and 3.3 Li per formula unit, respectively of which reversible extraction of 2.2 Li, 1.3 Li and 2.6 Li respectively, is possible. The results of cycling studies show that FeVMoO7 and AlVMoO7 phases exhibit a reversible capacity of 160 mAhg-1 and 180 mAhg-1 without any noticeable capacity fading even after 20 cycles. Reversibility of reaction of Li is more facile in AlVMoO7 vis-à-vis the other phases.