Nanocrystallisation in vanadate phosphate and lithium iron vanadate phosphate glasses

In this paper we have summarised our recent research on nanocrystallisation in vanadate-phosphate (VP) and lithium-iron-vanadate-phosphate (LFVP) glasses. These materials are amorphous analogues of crystalline V2O5 or LiFePO4 cathode materials for Li-ion batteries. The influence of synthesis and further thermal treatment conditions on electrical, thermal and electrochemical properties has been studied. In particular, a significant increase in electronic conductivity (up to 0.7x10(-1) and 7x10(-3) S/cm for VP and LFVP nanomaterials, respectively) was observed as a result of thermal nanocrystallisation. The microstructure has been observed and studied by a combination of XRD, SEM/TEM and EDX methods. Densely packed, small (15-30 nm and 5-15 nm in size) grains were observed in VP and LFVP materials, respectively. The significant increase in the conductivity is discussed in terms of Mott's model of electron hopping and a core-shell model.