Overcoming the Low-Temperature Barrier: Controlling Li₂S Deposition and Enhancing Catalysis in Lithium-Sulfur...

Low-temperature lithium-sulfur batteries (LSBs) face challenges such as Li₂S accumulation and the slow conversion of lithium polysulfides (LiPSs), significantly affecting their capacity and cycling life. While functionalizing cathode shows potential to overcome these problems, there has been little focus on understanding the deposition behavior of Li₂S at low temperatures and the specific catalysis processes of newly identified platforms. Here we report an island-like Bi₂O₃ uniformly distributed on reduced graphene oxide (IBG) as a sulfur host material. This unique island-like structure increases the contact area between the electrolyte and electrode, thus enhancing Li⁺ transport efficiency. More importantly, the IBG structure exhibits a targeted catalytic ability toward LiPSs at low temperatures, significantly accelerating the conversion of Li₂S₈ to Li₂S₄ and subsequently to Li₂S. Moreover, the nucleation of Li₂S on the IBG cathode follows a progressive mode with fewer nuclei, effectively preventing Li₂S accumulation and enhancing the battery's charge-discharge efficiency. As a result, LSBs using IBG as the sulfur host can operate reliably at extremely low temperatures, down to -60 °C. This remarkable performance broadens the operating temperature range of LSBs and offers valuable insights for selecting high-performance cathode modification materials in the future.