High-voltage lithium-metal batteries enabled by ethylene glycol bis(propionitrile) ether-LiNO₃ synergetic additives

The employment of Li metal anodes is a key to realizing ultra-high energy batteries. However, the commercialization of lithium metal batteries (LMBs) remains challenging partially due to the thermodynamic instability and competitive oxidative decomposition of the solvent. Herein, a bi-functional electrolyte for stabilizing the interfaces of both the Li metal anode and LiCoO2 (LCO) cathode is designed by introducing lithium nitrate (LiNO3) through Ethylene Glycol Bis(Propionitrile) Ether (DENE). For the anode, the C8H(12)N(2)O(2)-LiNO3 coordination-solvation contributes to forming a stable Li3N-enhanced solid electrolyte interphase (SEI), which increases the average Li coulombic efficiency (CE) up to 98.5%. More importantly, in situ electrochemical dilatometry further reveals that the highly reversible behavior and a low volume expansion of lithium deposition are related to the stable Li3N-enhanced SEI. The designed electrolyte enables the Li||LCO cell to achieve an average CE of 99.2% and a high capacity retention of 88.2% up to 4.6 V after 100 cycles. This work provides a strategic guidance in developing high-voltage Li||LCO batteries with dual electrolyte additives.