No abstract

The development of next-generation rechargeable lithium–metal batteries (LMBs) is critical to improving the performance of existing lithium-ion batteries. However, uncontrollable lithium dendrite growth and unstable solid electrolyte interphases (SEI) in lithium–metal anodes result in poor cycling efficiency and pose considerable safety risks, limiting their practical applications. A previous study showed that a marginal amount of Mg doping on the Li anode may aid in the formation of major SEI components on the surface, thereby improving the electrochemical performance of LMBs. However, the detailed decomposition mechanism of the electrolyte and the stability of the SEI layer following this doping process remain unknown. Therefore, in this study, ab initio molecular dynamics (AIMD) simulations were applied to investigate the interfacial reactions between the electrolytes and the Mg-doped Li metal anode surface. Commercialized lithium salts, lithium hexafluorophosphate (LiPF6), ethylene carbonate (EC), and diethyl carbonate (DEC) were selected as the electrolyte mixtures in our 3.6 M concentration model. Our results demonstrate that the Mg-doped lithium anode facilitates the decomposition of LiPF6 and solvents, forming a denser SEI layer than that of the pristine Li anode. Furthermore, we calculated the charged systems to simulate the conditions during the charging process and found that an increased amount of LiPF6 could easily decompose and form a fluoride-rich SEI layer in the charged system, especially in the Mg-doped case. We therefore confirmed that the Mg-doped Li anode facilitated the formation of a stable SEI layer to suppress the dendrite growth.