Stable Dendrite-Free Room Temperature Sodium-Sulfur Batteries Enabled by a Novel Sodium Thiotellurate Interface.

The practical application of room-temperature sodium-sulfur (RT Na-S) batteries was severely hindered by inhomogeneous sodium deposition and notorious sodium polysulfides (NaPSs) shuttling. Herein, novel sodium thiotellurate (Na2TeS3) interfaces are constructed both on the cathode and anode for Na-S batteries to simultaneously address the Na dendritic growth and polysulfide shuttling. On the cathode side, a heterostructural sodium sulfide/sodium telluride embedded in a carbon matrix (Na2S/Na2Te@C) was rationally designed through a facile carbothermal reaction, where the Na2TeS3interface will be in-situ chemically obtained. Such an interface provides abundant electron/ion diffusion channels and ensures rich catalytic surfaces toward Na-S redox, which could significantly improve the utilization of active material and alleviate polysulfide shuttling in the cathode. On the anode side, the inevitable formation of soluble polytellurosulfides species will migrate on Na anode surface, finally constructing a compact and smooth solid-electrolyte Na2TeS3 interphase (SEI) layer. Such electrochemical formed Na2TeS3 interface can significantly enhance ionic transport and stabilize Na deposition, thus realizing dendrite-free Na-metal plating/stripping. Benefitting from these advantages, an anode-free cell fabricated with the Na2S/Na2Te@C cathode exhibits an ultrahigh initial discharge capacity of 634 mAh g-1 at 0.1 C, which could pave a new path to design high-performance cathodes for anode-free RT Na-S batteries.

3D Flower-like Nanospheres Constructed by Transition Metal Telluride Nanosheets as Sulfur Immobilizers for High-Performance Room-Temperature Na-S Batteries.

Room-temperature sodium-sulfur (RT Na-S) batteries hold immense promise as next-generation energy storage systems, owing to their exceptionally high theoretical capacity, abundant resources, eco-friendliness, and affordability. Nevertheless, their practical application is impeded by the shuttling effect of sodium polysulfides (NaPSs) and sluggish sulfur redox kinetics. In this study, an advanced strategy by designing 3D flower-like molybdenum telluride (MoTe2) as an efficient catalyst to promote sulfur redox for RT Na-S batteries is presented. The unique 3D flower-like MoTe2 effectively prevents NaPS shuttling and simultaneously offers abundant active catalytic sites facilitating polysulfide redox. Consequently, the obtained MoTe2/S cathode delivers an outstanding initial reversible capacity of 1015 mAh g-1 at 0.1 C, along with robust cycling stability of retaining 498 mAh g-1 at 1 C after 500 cycles. In addition, pouch cells are fabricated with the MoTe2 additive to deliver an ultrahigh initial discharge capacity of 890 mAh g-1 and remain stable over 40 cycles under practically necessary conditions, demonstrating the potential application in the commercialization of RT Na-S batteries.

Boron nitride nanosheets wrapped by reduced graphene oxide for promoting polysulfides adsorption in lithium-sulfur batteries.

The polysulfides shuttling and slow redox kinetics of sulfur-based cathodes have severely hindered the commercialization of lithium-sulfur (Li-S) batteries. Herein, distinctive three-dimensional microspheres composed of boron nitride (BN) nanosheets and reduced graphene oxide (rGO) were applied to act as efficient sulfur cathode hosts for the first time using in a spray-drying process. Using this construction, the robust microsphere structure could shorten ion diffusion pathways and supply sufficient spaces to alleviate the volumetric expansion of sulfur during lithiation. Besides, the synergistic effect between BN and rGO significantly enhanced polysulfides adsorption capability and accelerated their conversion, verified by the density functional theory (DFT) calculations and adsorption experiments. Consequently, the S-BN@rGO cathode could manifest the high initial capacity (1137 mAh g-1 at 0.2 C) and remarkable cycling/stability performance (572 mAh g-1 at 1 C after 500 cycles). These results shed light on a design concept of high-performance sulfur cathode host materials.

Combined enhanced redox kinetics and physiochemical confinement in three-dimensionally ordered macro/mesoporous TiN for highly stable lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries with tremendous energy density possess great promise for the next-generation energy storage devices. Even though, the shuttle effect and sluggish redox kinetics of lithium polysulfides (LiPSs) seriously restrict practical applications of Li-S batteries. Herein, a three-dimensionally ordered macro/mesoporous TiN (3DOM TiN) nanostructure is established via using poly (methyl methacrylate) PMMA spheres as template. The interconnected macro/mesoporous channels are constructed to effectively alleviate the stacking of composite materials and render a large portion of inherent active sites exposed on the surface region. Moreover, TiN exhibits high electrical conductivity, which efficiently enhances charge-transfer kinetics and guarantees the favorable electrochemical performance of sulfur cathode. More importantly, the as-prepared 3DOM TiN suppresses the shuttle effect and improves the redox kinetics significantly due to strong affinity toward LiPSs. Attributed to these unique features, the S/3DOM TiN electrode achieves an ultrahigh initial discharge capacity of 1187 mAh g-1at 0.2 C, and stable cycling performance of 552 mAh g-1over 500 cycles at 1 C. Meanwhile, the discharge capacity retention of 701 mAh g-1(3.5 mAh cm-2) can be endowed for the S/3DOM TiN electrode under high sulfur loading of 5 mg cm-2after 100 cycles at 0.1 C. Therefore, the 3DOM TiN nanostructure electrocatalyst provides a promising path for developing practically useable Li-S batteries.