  Lithium-ion batteries (LIBs) are crucial for the green economy, powering
portable electronics, electric vehicles, and renewable energy systems. The
solid-electrolyte interphase (SEI) is vital for LIB operation, performance, and
safety. SEI forms due to thermal instability at the anode-electrolyte
interface, with electrolyte reduction products stabilizing it as an
electrochemical buffer. This article aims to enhance the parametrization of the
ReaxFF force field for accurate molecular dynamics (MD) simulations of SEI in
LIBs.
  Focus is on Lithium Fluoride (LiF), an inorganic salt with favorable
properties in the passivation layer. The protocol heavily relies on Python
libraries for atomistic simulations, enabling robust automation of
reparameterization steps. The proposed configurations and dataset enable the
new ReaxFF to accurately represent the solid nature of LiF and improve mass
transport property prediction in MD simulations. Optimized ReaxFF surpasses
previous force fields by adjusting lithium diffusivity, resulting in a
significant improvement in room temperature prediction by two orders of
magnitude.
  However, our comprehensive investigation reveals ReaxFF's strong sensitivity
to the training set, challenging its ability to interpolate the potential
energy surface. Consequently, the current ReaxFF formulation is suitable for
modeling specific phenomena by utilizing the proposed interactive
reparameterization protocol and constructing a dataset. This work is an
important step towards refining ReaxFF for precise reactive MD simulations,
shedding light on challenges and limitations in force field parametrization.
The demonstrated limitations underscore the potential for developing more
advanced force fields through our interactive reparameterization protocol,
enabling accurate and comprehensive MD simulations in the future.
