Enhanced Cycling Stability of High-Voltage Lithium Metal Battery with Trifunctional Electrolyte Additive

Carbonate-based electrolytes have been extensively employed in commercial Li-ion batteries, but they faces numerous interphasial stability challenges while supporting the high-voltage cathode chemistries and lithium metal anode, which result in electrolyte decomposition, electrode polarization, lithium dendritic growth and transition metal dissolution during cycling. Herein, a novel multifunctional electrolyte additive, trimethoxy(3,3,3-trifluoropropyl)silane (TTS), is proposed to address these challenges simultaneously. Through preferential reduction and oxidation, TTS constructs high stability protective films on both lithium metal and high voltage cathode surfaces, which effectively inhibits electrolyte decomposition, electrode polarization and lithium dendrite formation during cycling. In particular, the Si and O element shows great capability on capturing and eliminating the detrimental HF in electrolyte. Capacity retention of a lithium metal battery constructed with a 5 V-class cathode LiNi0.5Mn1.5O4/Li achieves 92% after 500 cycles in presence of only 2% TTS, which is 44% better than the reference without the additive.