ИСТИНА

In a hunt for high-energy cathode materials for Li-ion batteries, different families of fluoride-containing materials such as fluoride-phosphates AxMPO4F (A = Li, Na; M = V, Mn, Fe, Co, Ni; x = 1, 2) have been extensively examined. Introduced to the lattice fluorine brings about not only an increase in operating voltages due to its highest electronegativity, but also a richer structural variety. In these systems the nature of alkali and transition metals strongly affects the adopting crystal structure, which in turn determines electrochemical properties. Due to a larger ionic radius compared to Li and Na and somewhat different crystal chemistry, K provides ample opportunities in searching and stabilizing new frameworks for reversible ion de/intercalation. Here we report on a novel vanadium-based AVPO4F (A = Li, K) cathode material adopting a KTP-type framework for high power rechargeable batteries with enhanced specific energy and excellent rate capability. Synthesis, structure and electrochemical properties of the obtained cathode material will be discussed in detail. A special focus will be given on structural peculiarities and substitution in the metal sublattice and their effect on the electrochemical performance in a Li anode cell.