Leveraging doping strategies and interface engineering to enhance catalytic transformation of lithium polysulfides for high-performance lithium-sulfur batteries.

The commercialization of lithium-sulfur (Li-S) batteries has faced challenges due to the shuttle effect of soluble intermediate polysulfides and the sluggish kinetics of sulfur redox reactions. In this study, a synergistic catalyst medium was developed as a high-performance sulfur cathode material for Li-S batteries. Termed A/R-TiO2@ Ni-N-MXene, this sulfur cathode material features an in-situ derived anatase-rutile homojunction of TiO2 nanoparticles on Ni-N dual-atom-doped MXene nanosheets. Using in-situ transmission electron microscopy (TEM) technique, we observed the growth process of the homojunction for the first time confirming that homojunctions facilitated charge transfer, while dual-atom doping offered abundant active sites for anchoring and converting soluble polysulfides. Theoretical calculations and experiments showed that these synergistic effects effectively mitigated the shuttle effect, leading to improved cycling performance of Li-S batteries. After 500 cycles at a 1C rate, Li-S batteries using A/R-TiO2@Ni-N-MXene as cathode materials exhibited stable and highly reversible capacity with a capacity decay of only 0.056 % per cycle. Even after 150 cycles at a 0.1C rate, a high-capacity retention rate of 62.8 % was achieved. Additionally, efficient sulfur utilization was observed, with 1280.76 mA h/g at 0.1C, 694.24 mA h/g at 1C, alongside a sulfur loading of 1.5-2 mg/cm2. The effective strategy based on homojunctions showcases promise for designing high-performance Li-S batteries.

High-Performance Sodium-Ion Batteries Enabled by 3D Nanoflowers Comprised of Ternary Sn-Based Dichalcogenides Embedded in Nitrogen and Sulfur Dual-Doped Carbon.

To make sodium-ion batteries a realistic option for everyday energy storage, a practicable method is to enhance the kinetics of Na+ reactions through the development of structurally stable electrode materials. This study utilizes ternary Sn-based dichalcogenide (SnS1.5 Se0.5 ) in the design of electrode material to tackle several issues that adversely hinder the performance and longevity of sodium-ion batteries. First, the incorporation of Se into the SnS structure enhances its electrical conductivity and stability. Second, the ternary composition restricts the formation of intermediates during the desodiation/sodiation process, resulting in better electrode reaction reversibility. Finally, SnS1.5 Se0.5 lowers the diffusion barrier of Na, thereby facilitating rapid and efficient ion transport within the electrode material. Moreover, nitrogen and sulfur dual-doped carbon (NS-C) is used to enhance surface chemistry and ionic/electrical conductivity of SnS1.5 Se0.5 , leading to a pseudocapacitive storage effect that presents a promising potential for high-performance energy storage devices. The study has successfully developed a SnS1.5 Se0.5 /NS-C anode, exhibiting remarkable rate capability and cycle stability, retaining a capacity of 647 mAh g-1 even after 10 000 cycles at 5 A g-1 in half-cell tests. In full-cell tests, Na3 V2 (PO4 )3 //SnS1.5 Se0.5 /NS-C delivers a high energy density of 176.6 Wh kg-1 . In addition, the Na+ storage mechanism of SnS1.5 Se0.5 /NS-C is explored through ex situ tests and DFT calculations. The findings suggest that the ternary Sn-based dichalcogenides can considerably enhance the performance of the anode, enabling efficient large-scale storage of sodium. These findings hold great promise for the advancement of high-performance energy storage devices for practical applications.