Multifunctional Additive for Electrolyte Stabilization and Electrode/Electrolyte Interphase Regulation in High-Voltage Lithium Metal Batteries

Lithium-metal batteries (LMBs) incorporating nickel-rich cathodes have the potential to achieve superior energy densities. However, challenges associated with the electrolyte-electrode interphases (EEIs) have impeded the successful transition of these advanced systems into practical applications. In this study, azidotrimethylsilane (ATMS) is introduced as a multifunctional additive for traditional carbonate-based electrolytes. The azido group in ATMS plays a dual role in electrochemical reactions, with multiple nitrogen (N) atoms engaging in both nucleophilic and electrophilic interactions. These N atoms tend to undergo preferential oxidation reactions at the cathode, forming a stable cathode electrolyte interphase, while also undergoing preferential reduction reactions at the anode to inhibit lithium dendrite growth. The Si-N bond in the ATMS structure has unique reactivity, effectively neutralizing HF produced from LiPF₆ decomposition, thus preventing the recurrent formation of EEIs in the battery. As a result, the long-cycle performance of Li||NCM811 is significantly improved, with capacity retention increasing from 34.7% in baseline electrolyte to 82.6% after 600 cycles. Similarly, ATMS enhances the cycling performance of Li||Li symmetric cells, extending their lifespan to over 800 h, and improves the Coulombic efficiency of Li||Cu cells from 81.6 to 91.6%. The synergistic effect of ATMS on both anodes and cathodes further significantly enhances the high-voltage performance of the LMBs.