Carbon Coated SnS/SnO2 Heterostructures Wrapping on CNFs as an Improved-Performance Anode for Li-Ion Batteries: Lithiation-Induced Structural Optimization upon Cycling

A PEGylated deep eutectic solvent for "bubbling" synthesis of SnO2/SnS heterostructure for the stable lithium-ion storage

Constructing heterostructures is an effective strategy for the synthesis of high-performance anode electrode materials for lithium-ion batteries (LIBs). In this study, a "bubbling" PEGylated deep eutectic solvent (DES) method is utilized to synthesize SnO2/SnS heterostructure nanodots anchored on carbon nanosheets (SnO2/SnS@CN). A comprehensive investigation of the physical and chemical processes during the "bubbling" reaction offers in-depth insights into the underlying mechanism of the PEGylated DES approach. The carbon nanosheet structure enhances the electrical conductivity between SnO2 particle units and, due to its excellent mechanical properties, significantly contributes to material stability. The nanodot configuration of the heterostructure further improves electron transfer and lithium-ion (Li+) migration within the SnO2 units. The SnO2/SnS@CN material exhibits outstanding Li+ storage performance, achieving a high capacity of 675.6 mA h/g at 1 A/g after 1000 cycles. These findings establish a theoretical foundation for preparing heterostructure anode materials using the "bubbling" PEGylated DES method.

Ternary g-C3N4/Co3O4/CeO2 nanostructured composites for electrochemical energy storage supercapacitors

Extensive use of fossil fuels causes heavy discharge of carbon dioxide, depleting energy resources and this requires environmentally friendly and effective energy storage materials. Hybrid supercapacitors (HSCs) are recently developed as effective energy storage materials enabling high capacitance retention rate and quick charging. Herein, synthesis of two-dimensional g-C3N4 nanosheets supported onto three-dimensional flower-like Co3O4/CeO2 (CoCe) ternary synergistic heterostructures are developed as effective electrodes for hybrid supercapacitor applications. Addition of g-C3N4 produces substantial surface active sites, enabling its synergistic effect with CoCe to enhance electrochemical performance having exceptional conductivity. The CoCe/g-C3N4 ternary composite electrode exhibits a higher specific capacitance of 1088.3 F g-1 at 1 A g-1 with 96 % of recycling stability over 5000 cycles, which is ∼5.5 and ∼5 folds higher specific capacitance than the pristine g-C3N4 and CoCe electrodes. EIS analysis revealed that CoCe/g-C3N4 electrode offered reduced charge transfer resistance compared to pristine electrodes. The fabricated two-electrode HSC device displays outstanding retention after 10,000 cycles with an ultra-high specific capacitance of 119.8 F g-1, excellent energy density 37.4 Wh kg-1 and power density of 749.9 W kg-1. This research showcases the perspectives of CoCe/g-C3N4 ternary electrodes in hybrid supercapacitors and other renewable energy storage devices.

Graphene-Like Carbon Film Wrapped Tin (II) Sulfide Nanosheet Arrays on Porous Carbon Fibers with Enhanced Electrochemical Kinetics as High-Performance Li and Na Ion Battery Anodes

SnS, is a promising anode material for lithium ion batteries (LIBs) and sodium ion batteries (SIBs), however, undergoes poor cyclic lifespan due to its huge volume changes and bad electroconductivity. Here, a modified CVD method is used to directly grow graphene-like carbon film on the surface of SnS nanosheet arrays which are supported by Co-, N-modified porous carbon fibers (CCF@SnS@G). In the strategy, the SnS nanosheet arrays confined into the integrated carbon matrix containing porous carbon fibers and graphene-like carbon film, perform a greatly improved electrochemical performance. In situ TEM experiments reveal that the vertical graphene-like carbon film can not only protect the SnS nanosheet from destruction well and enhance the conductivity, but also transforms SnS nanosheet into ultrafine nanoparticles to promote the electrochemical kinetics. Systematic electrochemical investigations exhibit that the CCF@SnS@G electrode delivers a stable reversible capacity of 529 mAh g-1 at a high current density of 5 A g-1 for LIBs and 541.4 mAh g-1 at 2 A g-1 for SIBs, suggesting its good potential for anode electrodes.

Sn(salen)-derived SnS nanoparticles embedded in N-doped carbon for high performance lithium-ion battery anodes

By simple pyrolysis of a tin salen complex [Sn(salen)] and sulfur powder at 700 °C, SnS nanoparticles with ∼20 nm thickness homogeneously embedded in nitrogen-doped carbon are prepared. When applied as lithium-ion battery anodes, the SnS/N-C nanocomposites exhibited long cycling stability and excellent rate capability.

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.

Sandwich-Like C@SnS@TiO2 Anodes with High Power and Long Cycle for Li-Ion Storage

Up to now, high energy density batteries can be easily achieved by using alloys or conversion materials with high theoretical capacities (such as silicon-based and tin-based materials). However, these anode materials tend to sacrifice power densities while maintaining high energy densities. Herein, a sandwich-like C@SnS@TiO₂ anode with both high capacity and high power is designed by controlling a close integration between interfacial layers. The volume expansion of the middle layer of the SnS in the C@SnS@TiO₂ anode is greatly constrained by a synergetic interaction of the TiO₂ core and the carbon shell. From the results of the real-time dynamic evolution of electrode thickness during charging and discharging processes, the sandwich-like C@0.5SnS@TiO₂ has a max expansion rate of 11.5% in the first lithiation, which is much lower than that of pristine SnS (89.2%), and the expansion of C@0.5SnS@TiO₂ is basically reversible in the following charging/discharging processes. As a result, the sandwich-like C@0.5SnS@TiO₂ anode delivers a stable capacity of 660mAh g^-1 at 50 mA g^-1 and manifests an excellent rate capability, with a capacity of 357.2 mAh g^-1 at 5A g^-1 and a recovery ability of nearly 100%. In addition, it exhibits an outstanding long lifespan, retaining 95.6% capacity after 2500 cycles at 1A g^-1. This work presents a durable tin-based anode with moderate capacity for high-energy batteries and offers some ideas for the delicate study of materials with severe expansion during circulation.

SnS/N-Doped carbon composites with enhanced Li+ storage and lifetime by controlled hierarchical submicron- and nano-structuring

Hollow and dense hierarchical SnS microspheres coated with a nitrogen doped carbon layer were synthesised, tested and compared as anodes in lithium ion battery half cells.

Hierarchical Nanostructured NiS/MoS2/C Composite Hollow Spheres for High Performance Sodium-Ion Storage Performance

Development of high performance electrode materials for sodium-ion batteries has been given a lot of attention in recent years but challenges remain. Herein, we have successfully synthesized the first NiS/MoS₂/C composite hollow spheres (NMSCHSs) via a facile hard template method combined with calcined sulfidation process. Owing to its unique hierarchical nanostructure with NiS nanoparticles embedded in shell wrapped with MoS₂ nanosheets, the NMSCHS-based anode electrodes exhibit superior rate capability and cycling stability, with a specific discharge capacity of 516 mAh g^-1 and 98.5% retention after 60 cycles at a current density of 0.1 A g^-1 and a discharge capacity of 398 mAh g^-1 even at 5 A g^-1.

Sandwich-like SnS2/Graphene/SnS2 with Expanded Interlayer Distance as High-Rate Lithium/Sodium-Ion Battery Anode Materials

SnS₂ materials have attracted broad attention in the field of electrochemical energy storage due to their layered structure with high specific capacity. However, the easy restacking property during charge/discharge cycling leads to electrode structure instability and a severe capacity decrease. In this paper, we report a simple one-step hydrothermal synthesis of SnS₂/graphene/SnS₂ (SnS₂/rGO/SnS₂) composite with ultrathin SnS₂ nanosheets covalently decorated on both sides of reduced graphene oxide sheets via C-S bonds. Owing to the graphene sandwiched between two SnS₂ sheets, the composite presents an enlarged interlayer spacing of ∼8.03 Å for SnS₂, which could facilitate the insertion/extraction of Li⁺/Na⁺ ions with rapid transport kinetics as well as inhibit the restacking of SnS₂ nanosheets during the charge/discharge cycling. The density functional theory calculation reveals the most stable state of the moderate interlayer spacing for the sandwich-like composite. The diffusion coefficients of Li/Na ions from both molecular simulation and experimental observation also demonstrate that this state is the most suitable for fast ion transport. In addition, numerous ultratiny SnS₂ nanoparticles anchored on the graphene sheets can generate dominant pseudocapacitive contribution to the composite especially at large current density, guaranteeing its excellent high-rate performance with 844 and 765 mAh g^-1 for Li/Na-ion batteries even at 10 A g^-1. No distinct morphology changes occur after 200 cycles, and the SnS₂ nanoparticles still recover to a pristine phase without distinct agglomeration, demonstrating that this composite with high-rate capabilities and excellent cycle stability are promising candidates for lithium/sodium storage.

High-Performance and Reactivation Characteristics of High-Quality, Graphene-Supported SnS2 Heterojunctions for a Lithium-Ion Battery Anode

SnS₂ has received tremendous attention as an anode material for lithium-ion batteries owing to its high theoretical capacity and low cost. However, its applications are limited by its inferior cycling stability and poor rate performance. In this study, graphene@SnS₂ heterojunction nanocomposites are synthesized using a microwave-assisted solvothermal approach on liquid-phase exfoliated graphene (LEGr). Compared with graphene oxides, LEGr layers with an intrinsic atomic structure show extraordinary conductivity and serve as robust substrates for in situ growth of SnS₂ with improved interfacial contact. A LEGr-derived SnS₂ hybrid shows remarkable storage capacity, superior rate capability, and excellent cycling stability. The storage capacity remains at 664 mAh g^-1 after 200 cycles at 300 mA g^-1 current density. Furthermore, lithiation-induced reactivation of LEGr-based SnS₂ is investigated using in situ transmission electron microscopy, giving an in-depth explanation of the electrochemical reaction mechanisms.

Integrated Anode Electrode Composited Cu⁻Sn Alloy and Separator for Microscale Lithium Ion Batteries

A novel integrated electrode structure was designed and synthesized by direct electrodepositing of Cu⁻Sn alloy anode materials on the Celgard 2400 separator (Cel-CS electrode). The integrated structure of the Cel-CS electrode not only greatly simplifies the battery fabrication process and increases the energy density of the whole electrode, but also buffers the mechanical stress caused by volume expansion of Cu⁻Sn alloy active material; thus, effectively preventing active material falling off from the substrate and improving the cycle stability of the electrode. The Cel-CS electrode exhibits excellent cycle performance and superior rate performance. A capacity of 728 mA·h·g-1 can be achieved after 250 cycles at the current density of 100 mA·g-1. Even cycled at a current density of 5 A·g-1 for 650 cycles, the Cel-CS electrode maintained a specific capacity of 938 mA·h·g-1, which illustrates the potential application prospects of the Cel-CS electrode in microelectronic devices and systems.

SnO2@rice husk cellulose composite as an anode for superior lithium ion batteries

The RHC 3D-network structure effectively alleviates the volume expansion of the SnO₂-based anode material and exhibits extraordinary electrochemical performance.

MnWO4 nanoparticles as advanced anodes for lithium-ion batteries: F-doped enhanced lithiation/delithiation reversibility and Li-storage properties

F-Doped MnWO4 nano-particles were synthesized by a one-pot hydrothermal reaction. When evaluated as an electrode material for a Li ion battery, the F-doped nano-MnWO4 delivers a theoretical capacity of 708 mA h g-1 and a long cycle life, as demonstrated by more than 85% capacity retention when cycled for 150 cycles.

Highly reversible and fast sodium storage boosted by improved interfacial and surface charge transfer derived from the synergistic effect of heterostructures and pseudocapacitance in SnO2-based anodes

Sodium-ion batteries have attracted worldwide attention as potential alternatives for large scale stationary energy storage due to the rich reserves and low cost of sodium resources. However, the practical application of sodium-ion batteries is restricted by unsatisfying capacity and poor rate capability. Herein, a novel mechanism of improving both interfacial and surface charge transfer is proposed by fabricating a graphene oxide/SnO₂/Co₃O₄ nanocomposite through a simple hydrothermal method. The formation of heterostructures between ultrafine SnO₂ and Co₃O₄ could enhance the charge transfer of interfaces owing to the internal electric field. The pseudocapacitive effect, which is led by the high specific area and the existence of ultrafine nanoparticles, takes on a feature of fast faradaic surface charge-transfer. Benefiting from the synergistic advantages of the heterostructures and the pseudocapacitive effect, the as-prepared graphene oxide/SnO₂/Co₃O₄ anode achieved a high reversible capacity of 461 mA h g^-1 after 80 cycles at a current density of 0.1 A g^-1. Additionally, at a high current density of 1 A g^-1, a high reversible capacity of 241 mA h g^-1 after 500 cycles is obtained. A full cell coupled by the as-prepared graphene oxide/SnO₂/Co₃O₄ anode and the Na₃V₂(PO₄)₃ cathode was also constructed, which exhibited a reversible capacity of 310.3 mA h g^-1 after 100 cycles at a current density of 1 A g^-1. This method of improving both interfacial and surface charge transfer may pave the way for the development of high performance sodium-ion batteries.

Mercaptopropionic Acid-Capped Wurtzite Cu9Sn2Se9 Nanocrystals as High-Performance Anode Materials for Lithium-Ion Batteries

In this research, we provide a simple but sound solution to address the low performance of lithium-ion batteries through preparation of wurtzite Cu₉Sn₂Se₉ nanoparticles with uniform size distribution and morphology via a hot injection colloidal approach as a promising anode material. The Cu₉Sn₂Se₉ nanoparticles anode exhibits superior rate performance and high reversible capacity of 979.8 mAh g^-1 in the 100th cycle at a current density of 100 mA g^-1, which is approximate 2 times of reported Cu-Sn-S framework (563 mA g^-1), 1.5 times of reported pristine Cu₂SnS₃ (621 mA g^-1) and comparable or higher than a number of reported Sn-based nanocomposites based anodes for lithium-ion batteries at the same cycle. The study demonstrate such outstanding properties are attributed to the high structural flexibility of the metal selenide and increased electronic connectivity by colloidal quantum dot ligand exchange procedure associated with mercaptopropionic acid (MPA). In addition, unlike most metal sulfides or selenides, it possesses a stepwise intercalation mechanism during the lithiation/delithiation cycles which is beneficial to buffer against volume variation of the alloy electrode materials. Such findings provide a new and feasible insight into guide the design and manufacturing of high performance lithium-ion batteries for a broad variety of engineering applications.

Recent Progress on Two-Dimensional Nanoflake Ensembles for Energy Storage Applications

The rational design and synthesis of two-dimensional (2D) nanoflake ensemble-based materials have garnered great attention owing to the properties of the components of these materials, such as high mechanical flexibility, high specific surface area, numerous active sites, chemical stability, and superior electrical and thermal conductivity. These properties render the 2D ensembles great choices as alternative electrode materials for electrochemical energy storage systems. More recently, recognition of the numerous advantages of these 2D ensemble structures has led to the realization that the performance of certain devices could be significantly enhanced by utilizing three-dimensional (3D) architectures that can furnish an increased number of active sites. The present review summarizes the recent progress in 2D ensemble-based materials for energy storage applications, including supercapacitors, lithium-ion batteries, and sodium-ion batteries. Further, perspectives relating to the challenges and opportunities in this promising research area are discussed.

(101) Plane-Oriented SnS2 Nanoplates with Carbon Coating: A High-Rate and Cycle-Stable Anode Material for Lithium Ion Batteries

Tin disulfide is considered to be a promising anode material for Li ion batteries because of its high theoretical capacity as well as its natural abundance of sulfur and tin. Practical implementation of tin disulfide is, however, strongly hindered by inferior rate performance and poor cycling stability of unoptimized material. In this work, carbon-encapsulated tin disulfide nanoplates with a (101) plane orientation are prepared via a facile hydrothermal method, using polyethylene glycol as a surfactant to guide the crystal growth orientation, followed by a low-temperature carbon-coating process. Fast lithium ion diffusion channels are abundant and well-exposed on the surface of such obtained tin disulfide nanoplates, while the designed microstructure allows the effective decrease of the Li ion diffusion length in the electrode material. In addition, the outer carbon layer enhances the microscopic electrical conductivity and buffers the volumetric changes of the active particles during cycling. The optimized, carbon coated tin disulfide (101) nanoplates deliver a very high reversible capacity (960 mAh g^-1 at a current density of 0.1 A g^-1), superior rate capability (796 mAh g^-1 at a current density as high as 2 A g^-1), and an excellent cycling stability of 0.5 A g^-1 for 300 cycles, with only 0.05% capacity decay per cycle.

Metastable Marcasite-FeS2 as a New Anode Material for Lithium Ion Batteries: CNFs-Improved Lithiation/Delithiation Reversibility and Li-Storage Properties

Marcasite (m-FeS₂) exhibits higher electronic conductivity than that of pyrite (p-FeS₂) because of its lower semiconducting gap (0.4 vs 0.7 eV). Meanwhile, as demonstrates stronger Fe-S bonds and less S-S interactions, the m-FeS₂ seems to be a better choice for electrode materials compared to p-FeS₂. However, the m-FeS₂ has been seldom studied due to its sophisticated synthetic methods until now. Herein, a hierarchical m-FeS₂ and carbon nanofibers composite (m-FeS₂/CNFs) with grape-cluster structure was designed and successfully prepared by a straightforward hydrothermal method. When evaluated as an electrode material for lithium ion batteries, the m-FeS₂/CNFs exhibited superior lithium storage properties with a high reversible capacity of 1399.5 mAh g^-1 after 100 cycles at 100 mA g^-1 and good rate capability of 782.2 mAh g^-1 up to 10 A g^-1. The Li-storage mechanism for the lithiation/delithiation processes of m-FeS₂/CNFs was systematically investigated by ex situ powder X-ray diffraction patterns and scanning electron microscopy. Interestingly, the hierarchical m-FeS₂ microspheres assembled by small FeS₂ nanoparticles in the m-FeS₂/CNFs composite converted into a mimosa with leaves open shape during Li⁺ insertion process and vice versa. Accordingly, a "CNFs accelerated decrystallization-recrystallization" mechanism was proposed to explain such morphology variations and the decent electrochemical performance of m-FeS₂/CNFs.

Boosted adsorption–photocatalytic activities and potential lithium intercalation applications of layered potassium hexaniobate nano-family

We demonstrated that the KN nano-family (including KN nanolaminas and nano hollow spheres) can be derived from the same Nb₂O₅-based hydrothermal reaction.