In situ fabrication of nitrogen-doped carbon-coated SnO2/SnS heterostructures with enhanced performance for lithium storage

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.

Designing nano-heterostructured nickel doped tin sulfide/tin oxide as binder free electrode material for supercapattery

New generation of electrochemical energy storage devices (EESD) such as supercapattery is being intensively studied as it merges the ideal energy density of batteries and optimal power density of supercapacitors in a single device. A multitude of parameters such as the method of electrodes preparation can affect the performance of supercapattery. In this research, nickel doped tin sulfide /tin oxide (SnS@Ni/SnO2) heterostructures were grown directly on the Ni foam and subjected to different calcination temperatures to study their effect on formation, properties, and electrochemical performance through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and electrochemical tests. The optimized SnS@Ni/SnO2 electrode achieved a maximum specific capacity of 319 C g- 1 while activated carbon based capacitive electrode exhibited maximum specific capacitance of 381.19 Fg- 1. Besides, capacitive electrodes for the supercapattery were optimized by incorporating different conductive materials such as acetylene black (AB), carbon nanotubes (CNT) and graphene (GR). Assembling these optimized electrodes with the aid of charge balancing equation, the assembled supercapattery was able to achieve outstanding maximum energy density and power density of 36.04 Wh kg- 1 and 12.48 kW kg- 1 with capacity retention of 91% over 4,000 charge/discharge cycles.

Insight into Reversible Conversion Reactions in SnO2 -Based Anodes for Lithium Storage: A Review

Various anode materials have been widely studied to pursue higher performance for next generation lithium ion batteries (LIBs). Metal oxides hold the promise for high energy density of LIBs through conversion reactions. Among these, tin dioxide (SnO₂ ) has been typically investigated after the reversible lithium storage of tin-based oxides is reported by Idota and co-workers in 1997. Numerous in/ex situ studies suggest that SnO₂ stores Li⁺ through a conversion reaction and an alloying reaction. The difficulty of reversible conversion between Li₂ O and SnO₂ is a great obstacle limiting the utilization of SnO₂ with high theoretical capacity of 1494 mA h g^-1 . Thus, enhancing the reversibility of the conversion reaction has become the research emphasis in recent years. Here, taking SnO₂ as a typical representative, the recent progress is summarized and insight into the reverse conversion reaction is elaborated. Promoting Li₂ O decomposition and maintaining high Sn/Li₂ O interface density are two effective approaches, which also provide implications for designing other metal oxide anodes. In addition, some in/ex situ characterizations focusing on the conversion reaction are emphatically introduced. This review, from the viewpoint of material design and advanced characterizations, aims to provide a comprehensive understanding and shed light on the development of reversible metal oxide electrodes.

Boosting Reversibility and Stability of Li Storage in SnO2 -Mo Multilayers: Introduction of Interfacial Oxygen Redistribution

Among the promising high-capacity anode materials, SnO₂ represents a classic and important candidate that involves both conversion and alloying reactions toward Li storage. However, the inferior reversibility of conversion reactions usually results in low initial Coulombic efficiency (ICE, ≈60%), small reversible capacity, and poor cycling stability. Here, it is demonstrated that by carefully designing the interface structure of SnO₂ -Mo, a breakthrough comprehensive performance with ultrahigh average ICE of 92.6%, large capacity of 1067 mA h g^-1 , and 100% capacity retention after 700 cycles can be realized in a multilayer Mo/SnO₂ /Mo electrode. Furthermore, high capacity retentions are also achieved in pouch-type Mo/SnO₂ /Mo||Li half cells and Mo/SnO₂ /Mo||LiFePO₄ full cells. The amorphous SnO₂ /Mo interfaces, which are induced by redistribution of oxygen between SnO₂ and Mo, can precisely adjust the reversible capacity and cycling stability of the multilayers, while the stable capacities are parabolic with the interfacial density. Theoretical calculations and in/ex situ investigation reveal that oxygen redistribution in SnO₂ /Mo heterointerfaces boosts Li-ion transport kinetics by inducing a built-in electric field and improves the reaction reversibility of SnO₂ . This work provides a new understanding of interface-performance relationship of metal-oxide hybrid electrodes and pivotal guidance for creating high-performance Li-ion batteries.

Binary-Metal Mn2SnO4 Nanoparticles and Sn Confined in a Cubic Frame with N-Doped Carbon for Enhanced Lithium and Sodium Storage

Sn-based materials have been popularly researched as anodes for energy storage due to their high theoretical capacity. However, the sluggish reaction kinetics and unsatisfied cycling stability caused by poor conductivity and dramatic volume expansion are still pivotal barriers for the development of Sn-based materials as anodes. In this work, the binary-metal Mn₂SnO₄ nanoparticles and Sn encapsulated in N-doped carbon (Sn@Mn₂SnO₄-NC) were fabricated by multistep reactions and employed as the anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The coexistence of binary metals (Sn and Mn) can improve intrinsic conductivity. Simultaneously, hollow architecture along with carbon relieves internal stress and prevents structural collapse. A Sn@Mn₂SnO₄-NC anode delivers an appealing capacity of 1039.5 mAh g^-1 for 100 cycles at 100 mA g^-1 and 823.8 mAh g^-1 for 600 cycles at 1000 mA g^-1 in LIBs. When evaluated as an anode in SIBs, the Sn@Mn₂SnO₄-NC anode tolerates up to 7000 cycles at 2000 mA g^-1 and maintains a capacity of 185.8 mAh g^-1. Quantified kinetic investigations demonstrate the high contribution of pseudocapacitive effects during the cycle process. Furthermore, density functional theory (DFT) calculations further verify that introduction of the second metal (Mn) improves the conductivity of the material, which is favorable for charge transport. This work is expected to provide a feasible preparation strategy for binary-metal materials to enhance the performance of lithium- and sodium-ion batteries.

Modern Nanocomposites and Hybrids as Electrode Materials Used in Energy Carriers

Over the past decades, the application of new hybrid materials in energy storage systems has seen significant development. The efforts have been made to improve electrochemical performance, cyclic stability, and cell life. To achieve this, attempts have been made to modify existing electrode materials. This was achieved by using nano-scale materials. A reduction of size enabled an obtainment of changes of conductivity, efficient energy storage and/or conversion (better kinetics), emergence of superparamagnetism, and the enhancement of optical properties, resulting in better electrochemical performance. The design of hybrid heterostructures enabled taking full advantage of each component, synergistic effect, and interaction between components, resulting in better cycle stability and conductivity. Nowadays, nanocomposite has ended up one of the foremost prevalent materials with potential applications in batteries, flexible cells, fuel cells, photovoltaic cells, and photocatalysis. The main goal of this review is to highlight a new progress of different hybrid materials, nanocomposites (also polymeric) used in lithium-ion (LIBs) and sodium-ion (NIBs) cells, solar cells, supercapacitors, and fuel cells and their electrochemical performance.

Tin Oxide Based Nanomaterials and Their Application as Anodes in Lithium-Ion Batteries and Beyond

Herein, recent progress in the field of tin oxide (SnO2 )-based nanosized and nanostructured materials as conversion and alloying/dealloying-type anodes in lithium-ion batteries and beyond (sodium- and potassium-ion batteries) is briefly discussed. The first section addresses the importance of the initial SnO2 micro- and nanostructure on the conversion and alloying/dealloying reaction upon lithiation and its impact on the microstructure and cyclability of the anodes. A further section is dedicated to recent advances in the fabrication of diverse 0D to 3D nanostructures to overcome stability issues induced by large volume changes during cycling. Additionally, the role of doping on conductivity and synergistic effects of redox-active and -inactive dopants on the reversible lithium-storage capacity and rate capability are discussed. Furthermore, the synthesis and electrochemical properties of nanostructured SnO2 /C composites are reviewed. The broad research spectrum of SnO2 anode materials is finally reflected in a brief overview of recent work published on Na- and K-ion batteries.

Heterostructured SnS/TiO2@C hollow nanospheres for superior lithium and sodium storage

Tin(ii) sulfide (SnS) is considered to be one of the most promising anode materials for lithium/sodium ion batteries (LIBs/SIBs) due to its high theoretical capacity and low-cost. However, its practical applications are severely impeded by its low electrical conductivity and large volume change upon cycling. Herein, we demonstrate a high-performance SnS/TiO₂ encapsulated by a carbon shell (SnS/TiO₂@C) synthesized by facile coprecipitation and annealing treatment. The exterior carbon coating can not only improve the conductivity, but also effectively relieve volume variation to maintain the structural integrity during cycling. Significantly, the internal SnS/TiO₂ heterostructure formed a built-in electric field to provide favorable driving force for ion transfer. Consequently, the synthesized SnS/TiO₂@C delivered a reversible capacity of 672.4 mA h g^-1 at 0.5 A g^-1 after 100 cycles for lithium storage and 331.2 mA h g^-1 at 0.2 A g^-1 after 200 cycles for sodium storage. Meanwhile, ultra-long lifespans of 3000 cycles at 5.0 A g^-1 with a capacity of 394.5 mA h g^-1 for LIBs and 750 cycles at 5.0 A g^-1 with a capacity of 295 mA h g^-1 for SIBs were achieved. The electrochemical reaction mechanisms of the SnS/TiO₂@C electrode have been investigated by in situ XRD, ex situ XRD, and ex situ HRTEM. Our work may offer further understanding of the hierarchical structure to boost the electrochemical properties of the electrode materials.

3D Graphene Networks Encapsulated with Ultrathin SnS Nanosheets@Hollow Mesoporous Carbon Spheres Nanocomposite with Pseudocapacitance-Enhanced Lithium and Sodium Storage Kinetics

The lithium and sodium storage performances of SnS anode often undergo rapid capacity decay and poor rate capability owing to its huge volume fluctuation and structural instability upon the repeated charge/discharge processes. Herein, a novel and versatile method is described for in situ synthesis of ultrathin SnS nanosheets inside and outside hollow mesoporous carbon spheres crosslinked reduced graphene oxide networks. Thus, 3D honeycomb-like network architecture is formed. Systematic electrochemical studies manifest that this nanocomposite as anode material for lithium-ion batteries delivers a high charge capacity of 1027 mAh g^-1 at 0.2 A g^-1 after 100 cycles. Meanwhile, the as-developed nanocomposite still retains a charge capacity of 524 mAh g^-1 at 0.1 A g^-1 after 100 cycles for sodium-ion batteries. In addition, the electrochemical kinetics analysis verifies the basic principles of enhanced rate capacity. The appealing electrochemical performance for both lithium-ion batteries and sodium-ion batteries can be mainly related to the porous 3D interconnected architecture, in which the nanoscale SnS nanosheets not only offer decreased ion diffusion pathways and fast Li⁺ /Na⁺ transport kinetics, but also the 3D interconnected conductive networks constructed from the hollow mesoporous carbon spheres and reduced graphene oxide enhance the conductivity and ensure the structural integrity.

Synergistical Coupling Interconnected ZnS/SnS2 Nanoboxes with Polypyrrole-Derived N/S Dual-Doped Carbon for Boosting High-Performance Sodium Storage

Metal sulfides possess tremendous potentials owing to their high specific capacity for sodium storage. However, the huge volume expansion, accompanied with structural collapse and unsatisfied electric conductivity upon continuous cycling, always lead to inferior rate capability and severe cycling fading. In this work, binary metal sulfide (ZnS/SnS₂ ) nanoboxes confined in N/S dual-doped carbon shell (ZSS@NSC) are fabricated through a facile co-precipitation method involving the wrapping of polypyrrole, and subsequent in situ sulfidation process. Such a well-designed heterogeneity between ZnS and SnS₂ provides rapid Na⁺ insertion and enhanced charge transport by creating an electric field at the heterointerface. More significantly, the formation of polypyrrole-derived N/S dual-doped carbon is synergistically coupled with the ZnS/SnS₂ to create a unique and robust architecture, further strengthening the interconnect function at the heterointerface, which improves electric/ion transfer and mitigates the volume variation during the long-term cycling process. Herein, this as-prepared ZSS@NSC exhibits satisfied specific capacity, excellent rate property, and superior cyclic stability (a reversible capacity of 456.2 mAh g^-1 with excellent capacity retention of 97.2% after 700 stable cycles at ultrahigh rate of 5 A g^-1 ). The boosted Na-storage properties demonstrate that the optimized strategy of structure-engineering has a broad prospect to promote energy storage applications.

Effect of Temperature and Capping Agents on Structural and Optical Properties of Tin Sulphide Nanocrystals

SnS nanocrystals were synthesized using bis(phenylpiperazine dithiocarbamate)tin(II) in oleic acid (OA) and octadecylamine (ODA) at three different temperatures (150, 190, and 230°C). XRD diffraction pattern confirms that OASnS and ODASnS nanoparticles are in the orthorhombic phase and the type of capping agent used affects the crystallinity. Transmission electron microscopy (TEM) images shows spherically shaped nanocrystals for oleic acid capped SnS (OASnS) while octadecylamine (ODASnS) are cubic. Monodispersed SnS of size range 10.67–17.74 nm was obtained at 150°C for OASnS while the biggest-sized nanocrystals were obtained at 230°C for ODASnS. Temperature and capping agents tuned the crystallite sizes and shapes of the as-prepared nanocrystals. Electron dispersive X-ray spectroscopy indicates the formation of tin sulphide with the presence of Sn and S peaks in the nanocrystals. Flowery and agglomerated spherical-like morphology were observed for ODASnS and OASnS nanocrystals, respectively, using a SEM (scanning electron microscope). Direct electronic band gaps of the synthesized SnS nanocrystals are 1.71–1.95 eV and 1.93–2.81 eV for OASnS and ODASnS nanocrystals, respectively.