Voltage and Temperature Limits of Advanced Electrolytes for Lithium-Metal Batteries
Isik Su Buyuker, Ben Pei, Hui Zhou, Xia Cao, Zhiao Yu, Sufu Liu, Weiran Zhang, Wu Xu, Ji‐Guang Zhang, Zhenan Bao, Yi Cui, Chunsheng Wang, M. Stanley Whittingham
Abstract
Several advanced electrolytes (mainly ether-based) have shown promising electrochemical performance in high-energy-density lithium-metal batteries. This work evaluates their thermal stability under abuse conditions to elucidate their safety limits compared to carbonate electrolytes typically used in Li-ion batteries. Electrolyte stability was assessed in conjunction with a LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode and a Li-metal anode at ultra-high voltages (≤4.8 V) and temperatures (≤300 °C). The onset and extent of heat release were monitored via isothermal microcalorimetry and differential scanning calorimetry. Most ether-based electrolytes show improved thermal resilience over carbonate electrolytes. While extreme voltages severely destabilize the ether-based electrolytes, a phosphate-based localized high-concentration electrolyte exhibits improved stability over carbonate electrolytes, even at 60 °C. Although thermal analysis during the first charge process may be insufficient to conclude the long-term advantages of these electrolytes, a more stable electrolyte identified under extreme voltage and temperature conditions provides valuable guidance for the safety of future electrolyte designs.