High-performance lithium–sulfur batteries with mXene-transition metal oxide decorated electrospun interlayers for optimized polysulfide conversion

Official URL: https://dx.doi.org/10.1155/er/8862016

Lithium-sulfur (Li–S) batteries offer exceptional theoretical energy density, yet their practical realization remains limited by polysulfide shuttling and sluggish redox kinetics. Conventional interlayers typically mitigate only one of these bottlenecks, either improving conductivity or providing polysulfide adsorption, which proves insufficient under realistic conditions. Here, we introduce a multifunctional interlayer composed of electrospun polyvinylidene fluoride (PVDF) nanofibers embedded with MXene/transition metal oxide (TMO) hybrids and compacted via hot pressing. This design uniquely integrates MXene’s conductivity, TMO’s strong polar–polar adsorption and catalytic activity, and PVDF’s structural flexibility, producing a single architecture capable of suppressing shuttle effects, accelerating LiPS conversion, and stabilizing the electrode-interlayer interface. Electrochemical evaluation demonstrates high discharge capacities of 1032 mAh g−1 for PVDF-calcined MXene (P-CM) interlayer and 931 mAh g−1 for PVDF-MXene/SnO2 (P-MS) interlayer at medium sulfur loading (2–3 mg cm−2), with outstanding long-term retention of 800 mAh g−1 after 100 cycles and ultralow fading rates of 0.23% and 0.18% per cycle. Strikingly, at high sulfur loadings (5–6 mg cm−2), both interlayers sustained similarly low decay rates (0.18% per cycle), highlighting their robustness under practical conditions. Electrochemical impedance spectroscopy revealed a > 94% reduction in polysulfide shuttle resistance, directly confirming the efficient immobilization and conversion of soluble lithium polysulfides (LiPSs). Moreover, Li + diffusion coefficients were boosted to 9.89 × 10−8 mg cm2 s−1, nearly two orders of magnitude higher than previously reported values, while postmortem X-ray photoelectron spectrometer (XPS) identified Sn–S, Sn–O, and S–Ti–C bonding as evidence of strong chemical interactions. This work presents the first electrospun PVDF-based interlayer integrating MXene/TMO hybrids, establishing a multifunctional strategy that concurrently resolves shuttling and redox kinetics limitations. The ability to maintain high stability at practical sulfur loadings, coupled with scalable electrospinning and hot-pressing fabrication, underscores its potential for enabling next-generation Li–S batteries.