Localized Recrystallization of a Lithium-Metal Anode during Fast Stripping in High-Activity Liquid Electrolytes

The
lithium-metal anode is one of the most promising candidates
for “beyond-lithium-ion” batteries thanks to its high
specific capacity and low negative electrochemical potential. However,
the electrode–electrolyte interface instability hinders its
commercialization in rechargeable batteries. During cycles of charging
and discharging, the lithium-metal anode is electrochemically plated
and stripped along with the morphological evolution, which determines
the cycling performance. In this work, with a phase-field model, we
computationally characterize the morphological evolution dynamics
during the plating and stripping steps at the lithium–metal–electrolyte
interface. Our model is valid in a wide range of lithium concentrations
in liquid electrolytes by incorporating nonidealities of electrolyte
solutions into the interfacial reaction kinetics. Intriguingly, at
fast stripping, i.e., high discharging overpotential, we observe an
unexpected localized recrystallization phenomenon in high-lithium-ion-concentration
valley regions. This recrystallization phenomenon mitigates the overall
reaction rate heterogeneity and provides a potential approach to improving
the morphological stability. Furthermore, we systematically investigate
the correlation between the recrystallization phenomenon and lithium-ion
activity and draw a simplified phase diagram for the overpotential-dependent
recrystallization.