3D Tungsten Disulfide/Carbon Nanotube Networks as Separator Coatings and Cathode Additives for Stable and Fast Lithium-Sulfur Batteries

Arginine as a Multifunctional Additive for High Performance S-Cathode

Advancement of sulfur (S) cathode of lithium-sulfur (Li-S) batteries is hindered by issues such as insulating nature of sulfur, sluggish redox kinetics, polysulfide dissolution and shuttling. To address these issues, we initiate a study on applying an important amino acid of protein, arginine (Arg), as a functional additive into S cathode. Based on our simulation study, the positively charged Arg facilitates strong interactions with polysulfides. The experimental results indicate that the interaction enable capability of trapping polysulfides within the S cathode, responsible for reducing shuttle effects. Furthermore, the positively charged Arg also promotes efficient ion diffusion and polysulfides conversion. The new findings include that, with addition of only 1 wt % Arg, the resultant cathode demonstrates effectively enhanced electrolyte wettability, polysulfide adsorption and redox kinetics, leading to enhanced rate performance and long-term cycling stability. This study highlights the great potential of amino acids being able to act as effective functional bio-additives in S cathode, paving a new way to high-performance and sustainable energy storage solutions.

Tungsten oxide nanowire clusters anchored on porous carbon fibers as a sulfur redox mediator for lithium-sulfur batteries

Addressing the sluggish redox kinetics of sulfur electrodes and mitigating the shuttle effect of intermediate lithium polysulfides (LiPS) are crucial for the advancement of high-energy lithium-sulfur batteries. Here, we introduce a pioneering flexible self-supporting composite scaffold that incorporates tungsten oxide nanowire clusters anchored on core-shell porous carbon fibers (WO3/PCF) for sulfur accommodation. The core of PCF serves as a robust electrode supporting scaffold, whereas the porous shell of PCF provides a 3D interconnected conductive network to accommodate sulfur, restrain polysulfide diffusion and buffer electrode expansion. The WO3 nanowire clusters not only entrap polysulfides but also function as a redox mediator to promote sulfur conversion, thus greatly mitigating the shuttle effect and boosting redox kinetics. The unique core-shell porous structure of PCF and the dual functionality of WO3 for LiPS capture and conversion contribute to the high capacity, exceptional cycling stability, and superior rate capability of the WO3/PCF/S cathode. Impressively, at a sulfur loading of 3.0 mg cm-2, it achieves an initial capacity of 1082 mA h·g-1 at 1 C with an ultralow decay rate of 0.039% over 1000 cycles. Even under a high sulfur loading of 6.1 mg cm-2, it maintains a reversible capacity of 536 mA h·g-1 after 1000 cycles with a decay rate of only 0.043% at 0.5 C.

Scalable 3D Honeycombed Co3O4 Modified Separators as Polysulfides Barriers for High-Performance Li-S Batteries

Lithium sulfur batteries (LSBs) are regarded as one of the most promising energy storage devices due to the high theoretical capacity and energy density. However, the shuttling lithium polysulfides (LiPSs) from the cathode and the growing lithium dendrites on the anode limit the practical application of LSBs. To overcome these challenges, a novel three-dimensional (3D) honeycombed architecture consisting of a local interconnected Co₃O₄ successfully assembled into a scalable modified layer through mutual support, which is coated on commercial separators for high-performance LSBs. On the basis of the 3D honeycombed architecture, the modified separators not only suppress effectively the "shuttle effects" but also allow for fast lithium-ions transportation. Moreover, the theoretical calculations results exhibit that the collaboration of the exposed (111) and (220) crystal planes of Co₃O₄ is able to effectively anchor LiPSs. As expected, LSBs with 3D honeycombed Co₃O₄ modified separators present a reversible specific capacity with 1007 mAh g^-1 over 100 cycles at 0.1 C. More importantly, a high reversible capacity of 808 mAh g^-1 over 300 cycles even at 1 C is also acquired with the modified separators. Therefore, this proposed strategy of 3D honeycombed architecture Co₃O₄ modified separators will give a new route to rationally devise durable and efficient LSBs.

Tessellated N-doped carbon/CoSe2 as trap-catalyst sulfur hosts for room-temperature sodium-sulfur batteries

The construction of highly conductive structure with excellent adsorption-catalytic properties to accelerate electron transfer and suppress polysulfides shuttle is considered as an effective strategy to achieve well-behaved sodium-sulfur batteries. Herein,...