Exploring SnS nanoparticles interpenetrated with high concentration nitrogen-doped-carbon as anodes for sodium ion batteries

Carbon-Coated MOF-Derived Porous SnPS3 Core-Shell Structure as Superior Anode for Sodium-Ion Batteries

Metal thiophosphites have recently emerged as a hot electrode material system for sodium-ion batteries because of their large theoretical capacity. Nevertheless, the sluggish electrochemical reaction kinetics and drastic volume expansion induced by the low conductivity and inherent conversion-alloying reaction mechanism, require urgent resolution. Herein, a distinctive porous core-shell structure, denoted as SnPS3@C, is controllably synthesized by synchronously phosphor-sulfurizing resorcinol-formaldehyde-coated tin metal-organic framework cubes. Thanks to the 3D porous structure, the ion diffusion kinetics are accelerated. In addition, SnPS3@C features a tough protective carbon layer, which improves the electrochemical activity and reduces the polarization. As expected, the as-prepared SnPS3@C electrode exhibits superior electrochemical performance compared to pure SnPS3, including excellent rate capability (1342.4 and 731.1 mAh g-1 at 0.1 and 4 A g-1, respectively), and impressive long-term cycling stability (97.9% capacity retention after 1000 cycles at 1 A g-1). Moreover, the sodium storage mechanism is thoroughly studied by in-situ and ex-situ characterizations. This work offers an innovative approach to enhance the energy storage performance of metal thiophosphite materials through meticulous structural design, including the introduction of porous characteristics and core-shell structures.

Structural engineering of SnS quantum dots embedded in N, S Co-Doped carbon fiber network for ultrafast and ultrastable sodium/potassium-ion storage

Tin sulfides have received significant attention as potential candidates for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to their abundance, high theoretical capacity, and favorable working potential. However, the inherent drawbacks such as slow kinetics, low intrinsic electronic conductivity, and significant volume change during cycling, have not been adequately addressed. In this study, we propose a rational and effective approach to simultaneously overcome these challenges by embedding stannous sulfide (SnS) quantum dots (QDs) within a crosslinked nitrogen (N) and sulfur (S) co-doped carbon fiber network (SnS-CFN). The well-dispersed and densely packed SnS QDs, measuring approximately 2 nm, not only minimize the diffusion distance of Na+/K+ ions but also buffer the volume expansion effectively. The N, S co-doped carbon fiber network in SnS-CFN serves as a highly conductive and stable support structure that inhibits SnS QDs aggregation, creates ion/electron transport channels, and alleviates volume variations. Density functional theory (DFT) calculations further confirm that the combination of SnS QDs and the N, S co-doped carbon effectively reduces the adsorbed energies in the interlayer of SnS-CFN. These advantages synergistically contribute to the exceptional sodium/potassium storage performance of the SnS-CFN composite. Consequently, SnS-CFN demonstrates exceptional cyclability, retaining a capacity of 251.5 mAh/g over 10,000 cycles, and exhibits excellent rate capability (299.5 mAh/g at 20 A/g) when employed in SIBs. When used in PIBs, a high capacity of 112.3 mAh/g at 2 A/g after 1000 cycles, a remarkable capacity of 51.4 mAh/g at 5 A/g after 10,000 cycles, and a remarkable rate capability with a specific capacity of 55.5 mAh/g at a high current density of 20 A/g have been achieved.

Sulfur-Mediated Interface Engineering Enables Fast SnS Nanosheet Anodes for Advanced Lithium/Sodium-Ion Batteries

Interface design is generally helpful to ameliorate the electrochemical properties of electrode materials but challenging as well. Herein, in situ sulfur-mediated interface engineering is developed to effectively raise the kinetics properties of the SnS nanosheet anodes, which is realized by a synchronous reduction and carbon deposition/doping process. The sulfur in the raw SnS₂ directly induces the sulfur-doped amorphous carbon layer onto the in situ reduced SnS nanosheet. In situ and ex situ electrochemical characterizations suggest that the sulfur-mediated interface layer can enhance the reversibility and kinetics properties, promote the ion/electron swift delivery, and maintain the configurational wholeness of the SnS nanosheet anodes. Consequently, a relatively high Li-storage capacity of 922 mAh g^-1 and Na-storage capacity of 349 mAh g^-1 at 1.0 A g^-1 even after 1000 and 300 long-term cycles are achieved, respectively. The facile method and excellent performance suggest the effective interface tuning for developing the SnS-based anodes for batteries and beyond.

The In-Situ Synthesis of a 3D SnS/N-Doped Graphene Composite with Enhanced Electrochemical Performance as a Low-Cost Anode Material in Sodium Ion Batteries

SnS/N-doped graphene (SnS/NG) composites are promising anode materials for sodium ion batteries. Generally, SnS is synthesized from SnCl₂·2H₂O. However, SnCl₂·2H₂O is not suitable for large-scale production due to its high price. Compared with SnCl₂·2H₂O, SnCl₄·5H₂O has a lower price, more stable chemical properties and better water solubility. Until now, there have been no related reports on the synthesis of SnS from SnCl₄·5H₂O. In this work, the fabrication of SnS/NG in a facile, two-step process, which combines a hot water bath and thermal annealing and uses SnCl₄·5H₂O as a precursor, is described. The mechanism of phase transformation in the direct synthesis of SnS from Sn⁴⁺ is also discussed in detail. Applying our methodology, SnS nanoparticles were grown in-situ on graphene sheets and wrapped by N-doped graphene sheets to form a 3D SnS/NG composite. With 35.35% content of graphene in the SnS/NG composite, the reversible specific capacity remained at 417.8 mAh/g at 1000 mA/g after 100 cycles, exhibiting a high specific capacity and good cycling stability. In addition, the composite also had an excellent rate performance, with a specific capacity of 366.9 mAh/g obtained even at 5000 mA/g. Meanwhile, the fast sodium storage kinetics of SnS/NG were also analyzed, providing some theoretical support for further study.