Enhanced cycling stability of high-voltage lithium metal batteries with a trifunctional electrolyte additive

Carbonate-based electrolytes have been extensively employed in commercial Li-ion batteries, but they face 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 trifunctional 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 anode and high voltage cathode surfaces, which effectively improves the interphasial stability of the electrode/electrolyte. In addition, the Si and O elements show great capability of capturing and eliminating the detrimental HF in the electrolyte. The capacity retention of lithium metal batteries constructed with a 5 V-class cathode LiNi0.5Mn1.5O4/Li reaches 92% after 500 cycles in the presence of only 2% TTS, which is 44% higher than that of the reference without the additive.