A High-Humidity-Tolerant Electrolyte for High-Voltage Lithium-Metal Batteries

Lithium-metal batteries (LMBs) paired with high-voltage cathodes hold considerable commercial promise. Their practical deployment, however, remains hindered by persistent challenges such as electrolyte decomposition at high voltages (>4.4 V vs. Li/Li⁺), lithium dendrite growth, and interfacial instability. Furthermore, the pronounced hygroscopicity of advanced electrolytes imposes stringent drying requirements during manufacturing, increasing complexity, and cost and thereby obstructing scalable, cost-effective production. Herein, we develop a humidity-tolerant, high-voltage electrolyte by incorporating perfluorooctyltriethoxysilane (PFOTS) as a co-solvent into fluorinated carbonates. The weak solvation of PFOTS with Li⁺ forms a molecular hydrophobic shield, enabling efficient water scavenging and suppressing LiPF₆ hydrolysis. PFOTS also preferentially decomposes to form a robust electrode-electrolyte interphase. Consequently, Li/LiNi_0.8Co_0.1Mn_0.1O₂ cells achieves 90% capacity retention after 600 cycles at 4.4 V and 87% after 400 cycles at 4.7 V. Remarkably, with 0.5 vol% added water (corresponding to a dew point of 15°C), the cell maintains 80% retention after 150 cycles. This unique electrolyte system not only significantly enhances the high-voltage performance of LMBs, but also alleviates the stringent humidity control requirements during manufacturing.