Multifunctional SnO₂ QDs/MXene Heterostructures as Laminar Interlayers for Improved Polysulfide Conversion and...

Poor cycling stability in lithium-sulfur (Li-S) batteries necessitates advanced electrode/electrolyte design and innovative interlayer architectures. Heterogeneous catalysis has emerged as a promising approach, leveraging the adsorption and catalytic performance on lithium polysulfides (LiPSs) to inhibit LiPSs shuttling and improve redox kinetics. In this study, we report an ultrathin and laminar SnO₂@MXene heterostructure interlayer (SnO₂@MX), where SnO₂ quantum dots (QDs) are uniformly distributed across the MXene layer. The combined structure of SnO₂ QDs and MXene, along with the creation of numerous active boundary sites with coordination electron environments, plays a critical role in manipulating the catalytic kinetics of sulfur species. The Li-S cell with the SnO₂@MX-modified separator not only demonstrates superior electrochemical performance compared to cells with a bare separator but also induces homogeneous Li deposition during cycling. As a result, an areal capacity of 7.6 mAh cm^-2 under a sulfur loading of 7.5 mg cm^-2 and a high stability over 500 cycles are achieved. Our work demonstrates a feasible strategy of utilizing a laminar separator interlayer for advanced Li-S batteries awaiting commercialization and may shed light on the understanding of heterostructure catalysis with enhanced reaction kinetics.