ae0c00668_si_001.pdf (1.23 MB)
Enhanced Performance Induced by Phase Transition of Li2FeSiO4 upon Cycling at High Temperature
journal contribution
posted on 2020-05-21, 15:52 authored by Titus Masese, Yuki Orikasa, Kentaro Yamamoto, Yosuke Hori, Rika Hagiwara, Yoshiharu UchimotoOwing
to its low cost, thermal stability, and theoretically high
capacity, Li2FeSiO4 has been a promising cathode
material for high-energy-density Li-ion (Li+) battery systems.
However, its poor rate performance and high voltage polarization attributed
to innately slow Li+ kinetics at room temperature have
fundamentally curbed its ascent into prominence. Here, the rate performance
of Li2FeSiO4 at high temperatures in electrolyte
comprising molten salt (ionic liquid) was investigated. Subsequently,
a comparison of the phase transition behavior observed at both high-temperature
and room-temperature cycling was elucidated. Our results show that
remarkable rate performance with good cyclability in conjunction with
low voltage polarization is attained upon cycling of Li2FeSiO4 at high temperatures, due to the faster phase transformation
from unstable monoclinic structures to thermodynamically stable orthorhombic
structures triggered by elevated temperature. What this study adds
to the burgeoning body of research work relating to the silicates
is that the initially slow phase transformation behavior observed
at room temperature can significantly be enhanced upon cycling at
elevated temperatures.