In Situ Electrochemically Deposited Mg Seeds Stabilizing the Lithium Metal Anode

Abstract

Lithium metal, recognized for its extremely low reaction potential and ultrahigh theoretical specific capacity, is regarded as the “Holy Grail” of anode materials. However, the formation of lithium dendrites result in rapid cell capacity degradation and considerable safety issues, hindering its further advancement. In this study, in situ Mg seeds are generated on the lithium metal surface during cycling by incorporating MgCl₂ into the electrolyte. These Mg seeds function as thiophilic sites, which lower the Li nucleation barrier and promote uniform Li nucleation and growth. Consequently, symmetric cells constructed with the carbonate electrolyte can cycle stably for over 400 h at a current density of 1 mA cm⁻² and a capacity of 1 mAh cm⁻². Notably, full cells using Li₄Ti₅O₁₂ as the cathode can maintain stable cycling for 300 cycles, achieving a capacity retention rate of 71.9 %. This method has demonstrated its effectiveness in mitigating lithium dendrites formation and enhancing the performance of lithium metal batteries.