Observation of dendrite formation at Li metal-electrolyte interface by a machine-learning enhanced constant potential framework.

Uncontrollable dendrites growth during electrochemical cycles leads to low Coulombic efficiency and critical safety issues in Li metal batteries. Hence, a comprehensive understanding of the dendrite formation mechanism is essential for further enhancing the performance of Li metal batteries. Machine learning accelerated molecular dynamics simulations can provide atomic-scale resolution for various key processes at an ab-initio level accuracy. However, traditional molecular dynamics simulation tools hardly capture Li electrochemical depositions, due to lack of an electrochemical constant potential condition. In this work, we propose a constant potential approach that combines a machine learning force field with the charge equilibration method to reveal the dynamic process of dendrites nucleation at Li metal anode surfaces. Our simulations show that inhomogeneous Li depositions, following Li aggregations in amorphous inorganic components of solid electrolyte interphases, can initiate dendrites nucleation. Our study provides microscopic insights for Li dendrites formations in Li metal anodes. More importantly, we present an efficient and accurate simulation method for modeling realistic constant potential conditions, which holds considerable potential for broader applications in modeling complex electrochemical interfaces.