Decoupling Kinetic and Shuttle Limitations in Li─S Batteries Enabled by Temperature Responsive Functional Interlayer

Lithium-sulfur batteries (LSBs) face intertwined challenges of sluggish Li₂S nucleation and polysulfide shuttling, which are strongly temperature-dependent. Here, we demonstrate that an electrocatalytic MXene interlayer can decouple these limitations by functioning differently under low, room, and elevated temperatures. Using potentiostatic nucleation studies, post-cycling FESEM, and ex situ XPS, we reveal that at low temperatures, the MXene accelerates Li₂S nucleation and enhances reaction kinetics, while at high temperatures it effectively anchors polysulfides, suppressing shuttle-induced degradation. This temperature-responsive behavior enables stable cycling, improved sulfur utilization, and mitigates dendrite formation across a wide thermal range (-10°C-55°C). These findings provide a mechanistic framework for designing interlayers that adaptively address kinetic and shuttle limitations, offering a new strategy for high-energy-density LSBs capable of stable operation under diverse thermal conditions.