ИСТИНА

In the search for new cathode materials for Li-ion batteries we explored the A2MPO4F and AMPO4F (A=Li, Na, K, and M=Co, Mn, Fe, V) fluoride-phosphate families. It was shown that the substitutions on the alkali and transition metal sites lead to the wide range of adopted structures. Thus, in the (Na, Li)2FePO4F system synthesis of sodium-containing counterpart, NaLiFePO4F, followed by subsequent electrochemical exchange of Na by Li results in the cathode material with a 3D “stacked” structure.2 In the (Na, Li)2CoPO4F system it provides a new low-temperature polymorph adopting a complex layered structure. The introduction of large potassium into the AVPO4F system gives a raise to a new cathode material with a KTP structure, which exhibits excellent rate capability.3 The reversible electrochemical activity demonstrated by these fluoride-phosphates in Li-cell will be discussed. A special attention will be given to the structure peculiarities and their impact on electrochemical properties of these materials