Designing bi-layer electrode-electrolyte interfaces with an asymmetric ether to enable wide-temperature lithium metal batteries

Lithium metal batteries (LMBs) are promising next-generation energy storage solutions, but face challenges in achieving stable performance across wide temperature ranges. While sulfurized polyacrylonitrile (SPAN) offers advantages over traditional sulfur positive electrodes, its compatibility with ether electrolytes remains problematic. This work introduces a temperature-resistant, anion-rich solvation structure using an asymmetric ether solvent, ethyl butyl ether, to enable Li | |SPAN batteries with a wide operational range of 100 °C ( − 40 to 60 °C). The tailored electrolyte fosters a bi-layer interphase on Li negative electrode, which is more effective than the conventional mosaic interphase in suppressing dendrite growth and electrochemically inactive Li accumulation. Concurrently, it builds a dual-layer interphase on the SPAN positive electrode, enabling rapid Li+ transport and shuttle-free sulfur conversion. The resultant Li | |SPAN batteries achieve 72.8% capacity retention after 1000 cycles at 60 °C and 1 C and stably operate at −40 °C and 0.1 C. Validation via an Ah-level pouch cell underscores practical feasibility. This work advances electrolyte design strategies for LMBs resilient to extreme environments, offering critical insights into interfacial engineering for next-generation energy storage systems. Lithium metal batteries suffer from instability under extreme temperatures. Here, the authors develop a weakly solvating electrolyte based on an asymmetric ether that builds bi-layer electrode-electrolyte interfaces, enabling Li | |SPAN batteries to operate reliably from −40 °C to 60 °C