1 research outputs found
Asymmetric Lithium Extraction and Insertion in High Voltage Spinel at Fast Rate
Spinel-structured ordered-LiNi0.5Mn1.5O4 (o-LNMO) has experienced a resurgence of interest in
the
context of reducing scarce elements such as cobalt from the lithium-ion
batteries. O-LNMO undergoes two two-phase reactions at slow rates.
However, it is not known if such phenomenon also applies at fast rates.
Herein, we investigate the rate-dependent phase transition behavior
of o-LNMO through in operando time-resolved X-ray
diffraction. The results indicate that a narrow region of the solid
solution reaction exists for charge and discharge at both slow and
fast rates. The overall phase transition is highly asymmetric at fast
rates. During fast charge, it is a particle-by-particle mechanism
resulting from an asynchronized reaction among the particles. During
fast discharge, it is likely a core–shell mechanism involving
transition from Li0+xNi0.5Mn1.5O4 to Li1+xNi0.5Mn1.5O4 in the outer layer of particles.
The Li0.5Ni0.5Mn1.5O4 phase
is suppressed during fast discharge and appears only through Li redistribution
upon relaxation