am7b07895_si_001.pdf (4.86 MB)
ε- and β‑LiVOPO4: Phase Transformation and Electrochemistry
journal contribution
posted on 2017-08-08, 00:00 authored by Hui Zhou, Yong Shi, Fengxia Xin, Fredrick Omenya, M. Stanley Whittinghamε- and β-LiVOPO4 were synthesized from the same precursor at different temperatures
in an air atmosphere. ε-LiVOPO4 is obtained at 400
and 700 °C. The 700 °C sample has better purity and crystallinity,
but the 400 °C sample has a little better electrochemical performance
due to its smaller particle size and the conducting carbon residue
in the sample. β-LiVOPO4 is formed between the above
two temperatures, which gives slightly lower capacity than that of
the ε-LiVOPO4 sample, indicating higher kinetics
of the lithium reaction for the ε phase than those of the β
one. The phase transformation from ε to β then back reversibly
to ε was also observed by ex situ X-ray diffraction. This thermal
study verifies that ε-LiVOPO4 is the more stable
phase for LiVOPO4; however, reaction kinetics control the
phases formed at lower temperatures.