Room-Temperature Synthesis Leading to Nanocrystalline Ag₂V₄O₁₁

Abstract

This work highlights a room-temperature composition study of the Ag(2)O/V(2)O(5)/HF((aq)) ternary system, leading to the precipitation of either various silver vanadates having Ag/V ratios from 1/2 to 3/1 or the new silver vanadium oxyfluoride compounds Ag(4)V(2)O(6)F(2) and Ag(3)VO(2)F(4), and a synthetic procedure that affords nanocrystalline Ag(2)V(4)O(11) (SVO) at room temperature. The as-precipitated SVO particles exhibit an acicular morphology, 10-15 x 50-200 nm in size, and present a peculiar reactivity vs lithium notably through a Ag(+)/Li(+) displacement reaction that progresses in a reversible fashion. This step forward thus enables the reversible and simultaneous combination of two active redox processes (silver and vanadium), providing a significant enhancement in the cathode gravimetric capacity of 320 mAh/g at C rate and more than 250 mAh/g at 5C.