Reaction sequence and electrochemical properties of lithium vanadium oxide cathode materials synthesized via a hydrothermal reaction

Abstract Lithium vanadium oxide (Li 1+ x V 3 O 8 ) cathode materials were synthesized via a simple hydrothermal reaction followed by heat treatment at 300 or 400 °C. From both XRD and TG/DTA analyses, a detailed comprehensive reaction sequence for the formation of single-phase LiV 3 O 8 is proposed. Li 1+ x V 3 O 8 ( x =0.2) materials with different thermal histories show clear differences in morphologies and sizes, although they maintained an impurity-free single phase regardless of thermal treatment. Samples that were heat treated at 300 °C show an agglomerated particle shape with many nanorod-like Li 1+ x V 3 O 8 particles over the surface that enhance the surface area of the particles. In contrast, samples treated at 400 °C have a bi-modal particle size distribution with improved crystallinity. Such differences in morphologies clearly influence the electrochemical properties. LiV 3 O 8 cathode materials that were treated at 300 and 400 °C showed initial discharge capacacities of 346.52 and 261.23 mA h/g, respectively, and discharge capacities of 78.66 and 157.35 mA h/g, respectively, after 100 cycles. The improved cyclability of LiV 3 O 8 cathode materials that were heat treated at 400 °C is due to their increased crystallinity and structural stability.