A Flexible Film with SnS2 Nanoparticles Chemically Anchored on 3D-Graphene Framework for High Areal Density and High Rate Sodium Storage

Lithium Azides Induced SnS Quantum Dots for Ultra-Fast and Long-Term Sodium Storage

Tin sulfide (SnS) is an attractive anode for sodium ion batteries (NIBs) because of its high theoretical capacity, while it seriously suffers from the inherently poor conductivity and huge volume variation during the cycling process, leading to inferior lifespan. To intrinsically maximize the sodium storage of SnS, herein, lithium azides (LiN3 )-induced SnS quantum dots (QDs) are first reported using a simple electrospinning strategy, where SnS QDs are uniformly distributed in the carbon fibers. Taking the advantage of LiN3 , which can effectively prevent the growth of crystal nuclei during the thermal treatment, the well-dispersed SnS QDs performs superior Na+ transfer kinetics and pseudocapacitive when used as an anode material for NIBs. The 3D SnS quantum dots embedded uniformly in N-doped nanofibers (SnS QDs@NCF) electrodes display superior long cycling life-span (484.6 mAh g-1 after 5800 cycles at 2 A g-1 and 430.9 mAh g-1 after 7880 cycles at 10 A g-1 ), as well as excellent rate capability (422.3 mAh g-1 at 20 A g-1 ). This fabrication of transition metal sulfides QDs composites provide a feasible strategy to develop NIBs with long life-span and superior rate capability to pave its practical implementation.

Balanced Crystallinity and Nanostructure for SnS2 Nanosheets through Optimized Calcination Temperature toward Enhanced Pseudocapacitive Na+ Storage

Sodium ion batteries (SIBs) are expected to take the place of lithium ion batteries (LIBs) as next-generation electrochemical energy storage devices due to the cost advantages they offer. However, due to the larger ion radius, the reaction kinetics of Na⁺ in anode materials is sluggish. SnS₂ is an attractive anode material for SIBs due to its large interlayer spacing and alloying reactions with high capacity. Calcination is usually employed to improve the crystallinity of SnS₂, which could affect the Na⁺ reaction kinetics, especially the pseudocapacitive storage. However, excessively high temperature could damage the well-designed nanostructure of SnS₂. In this work, we uniformly grow SnS₂ nanosheets on a Zn-, N-, and S-doped carbon skeleton (SnS₂@ZnNS). To explore the optimal calcination temperature, SnS₂@ZnNS is calcined at three typical temperatures (300, 350, and 400 °C), and the electrochemical performance and Na⁺ storage kinetics are investigated specifically. The results show that the sample calcined at 350 °C exhibited the best rate capacity and cycle performance, and the reaction kinetics analysis shows that the same sample exhibited a stronger pseudocapacitive response than the other two samples. This improved Na⁺ storage capability can be attributed to the enhanced crystallinity and the intact nanostructure.

Rational Design Hierarchical SnS2 Uniformly Adhered to Three-Sided Carbon Active Sites to Enhance Sodium Storage

Reducing material accumulation and designing reasonable sizes are critical strategies for increasing the rate and cycling stability of electrode materials. Herein, we presented a double-walled hollow carbon spheres (DWHCSs) loading strategy for achieving ultrafine SnS₂ nanosheet adhesion by utilizing three-sided active sites of the interior/exterior carbon walls. The structure effectively shortened the electron/ion transport path, increased the effective contact between electrolyte and electrode material, and promoted ion diffusion kinetics. Furthermore, the hollow structure can adapt to the volume change of the electrode during the cycle, preventing active substances from draining. Based on the above advantages, SnS₂@DWHCSs as an anode material for sodium ion batteries (SIBs) exhibited a distinguished reversible capacity of 665.7 mA h g^-1 at 2 A g^-1 after 1000 cycles, and a superior rate ability of 377.6 mA h g^-1 at an ultrahigh rate of 10 A g^-1. The outstanding electrochemical performance revealed that the structure exhibited a broad application prospect in the field of energy storage and provided a reference for the rational design of other 2D materials.

Phosphorus Doping Induced the Co-Construction of Sulfur Vacancies and Heterojunctions in Tin Disulfide as a Durable Anode for Lithium/Sodium-Ion Batteries

The reasonable design of electrode materials with heterojunction and vacancy is a promising strategy to elevate its electrochemical performances. Herein, tin-based sulfide composites with heterojunction and sulfur vacancy encapsulated by...

A novel interlayer-expanded tin disulfide/reduced graphene oxide nanocomposite as anode material for high-performance sodium-ion batteries

As a kind of negative electrode material for sodium-ion batteries (SIBs), tin-based active compounds have attracted numerous research efforts in recent years due to relatively high theoretical capacity. However, sluggish reaction kinetics for large-radius sodium ions hinders the practical application of layered tin-based anodes such as tin disulfide (SnS₂) in SIBs. In this study, polyethylene glycol (PEG) is introduced as an intercalant and reduced graphene oxide (rGO) is utilized as the substrate to prepare a novel PEG-SnS₂/rGO composite with expanded layer spacing (0.921 nm) through a facile hydrothermal process. SnS₂ flakes in a size range of 50-100 nm are uniformly grown on the graphene sheet, the CS covalent bonding demonstrates a tight connection between the active SnS₂ particles and the graphene skeleton, which is conductive to convenient charge transfer during the electrochemical process. Owing to the significantly improved sodium ions transport kinetics and fast electronic conductive network, the PEG-SnS₂/rGO composite presents a high capacitance contribution of 90.69% at a scan rate of 0.6 mV s^-1. It delivers a high reversible capacity of 960.6 mAh g^-1 at 0.1 A g^-1, good cycling performance with 770 mAh g^-1 remained after 100 charge/discharge cycles, and excellent rate capability with an ultrahigh capacity of 720 mAh g^-1 at 5 A g^-1. This work provides new insights into the design of a kinetically favorable anode material for SIBs.

3D Carbon Networks: Design and Applications in Sodium Ion Batteries

As the key component of a new generation for low-cost energy storage systems, sodium-ion batteries (SIBs) have attracted enormous attention and research due to its promising potentiality in large-scale electrochemical energy storage. For practical application of SIBs, carbonaceous materials have been considered to be one of the best choices for electrodes in virtue of their abundant reserves, low cost, easy availability, and environmental friendliness. 3D carbon network (3D-carbon) is of particular interests, which has displayed outstanding features, including abundant active sites, interconnected multi-level pore structures, high electronic conductivity, and excellent mechanical stability. Herein, we review the structural advantages of 3D-carbon and its preparation methods, and then discuss recent progress in 3D carbon materials and their composites for SIBs. The superior functionalities of 3D-carbon are emphasized as support templates or encapsulation shell membranes. Finally, we summarize and outline the challenges and future prospects of 3D-carbon in SIBs.

Selective Interface Synthesis of Cobalt Metaphosphate Nanosheet Arrays Motivated by Functionalized Carbon Cloths for Fast and Durable Na/K-Ion Storage

Exploiting novel nanomaterials with fast and durable sodium/potassium ion storage capability is key to alleviate the application limitations of lithium-ion batteries. Herein, a novel energy storage material based on cobalt metaphosphate nanosheet arrays self-supported on carbon cloths [Co(PO₃)₂ NSs/CC] is fabricated by a two-step strategy. This rationally designed strategy avoids the preparation of the complex {Co[O₂P(O^tBu)₂]₂}_n precursor, which significantly simplifies the synthesis process. The active CC acts not only as an electrically conductive substrate as usual but also as a functional basis to suppress PH₃-involved reaction and to promote HPO₃-involved reaction during the phosphating process, contributing to the formation of Co(PO₃)₂. The mutual cross-linked porous Co(PO₃)₂ nanosheets vertically grow on the surface of activated CC, ensuring sufficient electrolyte infiltration and fast electron transport among the electrodes. Sodium ion storage analysis for the Co(PO₃)₂ NSs/CC electrode reveals a multi-step reaction mechanism with high reversibility, as reflected by the high reversible capacity (667 mA h g^-1 at 50 mA g^-1) and excellent cyclability (with almost no capacity decay over 500 cycles). This novel electrode is also well capable of storing potassium ions, exhibiting high reversible capacity, which outperforms most reported anodes for potassium-ion batteries. The development of this novel high-performance nanomaterial would advance the performance of sodium/potassium-ion batteries toward practical applications.

SnS2 Nanosheets with RGO Modification as High-Performance Anode Materials for Na-Ion and K-Ion Batteries

To date, the fabrication of advanced anode materials that can accommodate both Na+ and K+ storage is still very challenging. Herein, we developed a facile solvothermal and subsequent annealing process to synthesize SnS2/RGO composite, in which SnS2 nanosheets are bonded on RGO, and investigated their potential as anodes for Na+ and K+ storage. When used as an anode in SIBs, the as-prepared SnS2/RGO displays preeminent performance (581 mAh g-1 at 0.5 A g-1 after 80 cycles), which is a significant improvement compared with pure SnS2. More encouragingly, SnS2/RGO also exhibits good cycling stability (130 mAh g-1 at 0.3 A g-1 after 300 cycles) and excellent rate capability (520.8 mAh g-1 at 0.05 A g-1 and 281.4 mAh g-1 at 0.5 A g-1) when used as anode for PIBs. The well-engineered structure not only guarantees the fast electrode reaction kinetics, but also ensures superior pseudocapacitance contribution during repeated cycles, which has been proved by kinetic analysis.

In situ chemically encapsulated and controlled SnS2 nanocrystal composites for durable lithium/sodium-ion batteries

SnS2 as the promising anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) still encounters the undesirable rate performance and cycle stability. Herein, a unique stable structure is developed, where the SnS2 nanocrystals (NCs) are sturdily encapsulated by carbon shells anchored on a reduced graphene oxide (rGO) via the one-pot solvothermal process. The well-controlled carbon shells provide the enduring protection for SnS2 NCs through C-S covalent bonds from the corrosion of electrolyte and pulverization of structure. Moreover, both experimental results and density functional theory (DFT) calculations demonstrate that the carbon protective shell effectively enhances the structure stability and conductivity of the resulting materials. Interestingly, the size of SnS2 NCs and the thickness of carbon shells are accurately controlled by regulating the content of glucose. Aided by the advanced electron/ion transfer kinetics and structure stability, the SnS2-based electrode exhibits desired lithium/sodium storage performance and unprecedented long-term cycling stability (capacity retention of 74.7% after 1000 cycles at 2 A g-1 for LIBs and 102% after 200 cycles at 500 mA g-1 for SIBs). This work develops a method for promoting the practical applications and large-scale production of SnS2 composites for energy storage devices.