SnO₂-based nanomaterials: synthesis and application in lithium-ion batteries

The role of graphene aerogels in rechargeable batteries

Energy storage systems, particularly rechargeable batteries, play a crucial role in establishing a sustainable energy infrastructure. Today, researchers focus on improving battery energy density, cycling stability, and rate performance. This involves enhancing existing materials or creating new ones with advanced properties for cathodes and anodes to achieve peak battery performance. Graphene aerogels (GAs) possess extraordinary attributes, including a hierarchical porous and lightweight structure, high electrical conductivity, and robust mechanical stability. These qualities facilitate the uniform distribution of active sites within electrodes, mitigate volume changes during repeated cycling, and enhance overall conductivity. When integrated into batteries, GAs expedite electron/ion transport, offer exceptional structural stability, and deliver outstanding cycling performance. This review offers a comprehensive survey of the advancements in the preparation, functionalization, and modification of GAs in the context of battery research. It explores their application as electrodes and hosts for the dispersion of active material nanoparticles, resulting in the creation of hybrid electrodes for a wide range of rechargeable batteries including lithium-ion batteries (LIBs), Li-metal-air batteries, sodium-ion batteries (SIBs), zinc-ion batteries (AZIBs) and zinc-air batteries (ZABs), aluminum-ion batteries (AIBs) and aluminum-air batteries and other.

Stannate-Based Materials as Anodes in Lithium-Ion and Sodium-Ion Batteries: A Review

Binary metal oxide stannate (M₂SnO₄; M = Zn, Mn, Co, etc.) structures, with their high theoretical capacity, superior lithium storage mechanism and suitable operating voltage, as well as their dual suitability for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), are strong candidates for next-generation anode materials. However, the capacity deterioration caused by the severe volume expansion problem during the insertion/extraction of lithium or sodium ions during cycling of M₂SnO₄-based anode materials is difficult to avoid, which greatly affects their practical applications. Strategies often employed by researchers to address this problem include nanosizing the material size, designing suitable structures, doping with carbon materials and heteroatoms, metal-organic framework (MOF) derivation and constructing heterostructures. In this paper, the advantages and issues of M₂SnO₄-based materials are analyzed, and the strategies to solve the issues are discussed in order to promote the theoretical work and practical application of M₂SnO₄-based anode materials.

Tailoring SnO2 Defect States and Structure: Reviewing Bottom-Up Approaches to Control Size, Morphology, Electronic and Electrochemical Properties for Application in Batteries

Tin oxide (SnO₂) is a versatile n-type semiconductor with a wide bandgap of 3.6 eV that varies as a function of its polymorph, i.e., rutile, cubic or orthorhombic. In this review, we survey the crystal and electronic structures, bandgap and defect states of SnO₂. Subsequently, the significance of the defect states on the optical properties of SnO₂ is overviewed. Furthermore, we examine the influence of growth methods on the morphology and phase stabilization of SnO₂ for both thin-film deposition and nanoparticle synthesis. In general, thin-film growth techniques allow the stabilization of high-pressure SnO₂ phases via substrate-induced strain or doping. On the other hand, sol-gel synthesis allows precipitating rutile-SnO₂ nanostructures with high specific surfaces. These nanostructures display interesting electrochemical properties that are systematically examined in terms of their applicability to Li-ion battery anodes. Finally, the outlook provides the perspectives of SnO₂ as a candidate material for Li-ion batteries, while addressing its sustainability.

High-Resolution Nanoanalytical Insights into Particle Formation in SnO2/ZnO Core/Shell Nanowire Lithium-Ion Battery Anodes

Tin oxide (SnO₂)/zinc oxide (ZnO) core/shell nanowires as anode materials in lithium-ion batteries (LIBs) were investigated using a combination of classical electrochemical analysis and high-resolution electron microscopy to correlate structural changes and battery performance. The combination of the conversion materials SnO₂ and ZnO is known to have higher storage capacities than the individual materials. We report the expected electrochemical signals of SnO₂ and ZnO for SnO₂/ZnO core/shell nanowires as well as unexpected structural changes in the heterostructure after cycling. Electrochemical measurements based on charge/discharge, rate capability, and electrochemical impedance spectroscopy showed electrochemical signals for SnO₂ and ZnO and partial reversibility of lithiation and delithiation. We find an initially 30% higher capacity for the SnO₂/ZnO core/shell NW heterostructure compared to the ZnO-coated substrate without the SnO₂ NWs. However, electron microscopy characterization revealed pronounced structural changes upon cycling, including redistribution of Sn and Zn, formation of ∼30 nm particles composed of metallic Sn, and a loss of mechanical integrity. We discuss these changes in terms of the different reversibilities of the charge reactions of both SnO₂ and ZnO. The results show stability limitations of SnO₂/ZnO heterostructure LIB anodes and offer guidelines on material design for advanced next-generation anode materials for LIBs.

Looking Outside the Square: The Growth, Structure, and Resilient Two-Dimensional Surface Electron Gas of Square SnO2 Nanotubes

Nanotechnology has delivered an amazing range of new materials such as nanowires, tubes, ribbons, belts, cages, flowers, and sheets. However, these are usually circular, cylindrical, or hexagonal in nature, while nanostructures with square geometries are comparatively rare. Here, a highly scalable method is reported for producing vertically aligned Sb-doped SnO₂ nanotubes with perfectly-square geometries on Au nanoparticle covered m-plane sapphire using mist chemical vapor deposition. Their inclination can be varied using r- and a-plane sapphire, while unaligned square nanotubes of the same high structural quality can be grown on silicon and quartz. X-ray diffraction measurements and transmission electron microscopy show that they adopt the rutile structure growing in the [001] direction with (110) sidewalls, while synchrotron X-ray photoelectron spectroscopy reveals the presence of an unusually strong and thermally resilient 2D surface electron gas. This is created by donor-like states produced by the hydroxylation of the surface and is sustained at temperatures above 400 °C by the formation of in-plane oxygen vacancies. This persistent high surface electron density is expected to prove useful in gas sensing and catalytic applications of these remarkable structures. To illustrate their device potential, square SnO₂ nanotube Schottky diodes and field effect transistors with excellent performance characteristics are fabricated.

Operando study of mechanical integrity of high-volume expansion Li-ion battery anode materials coated by Al2O3

Group IV elements and their oxides, such as Si, Ge, Sn and SiO have much higher theoretical capacity than commercial graphite anode. However, these materials undergo large volume change during cycling, resulting in severe structural degradation and capacity fading. Al₂O₃coating is considered an approach to improve the mechanical stability of high-capacity anode materials. To understand the effect of Al₂O₃coating directly, we monitored the morphology change of coated/uncoated Sn particles during cycling using operando focused ion beam-scanning electron microscopy. The results indicate that the Al₂O₃coating provides local protection and reduces crack formation at the early stage of volume expansion. The 3 nm Al₂O₃coating layer provides better protection than the 10 and 30 nm coating layer. Nevertheless, the Al₂O₃coating is unable to prevent the pulverization at the later stage of cycling because of large volume expansion.

Development of Cellulose Nanofiber-SnO2 Supported Nanocomposite as Substrate Materials for High-Performance Lithium-Ion Batteries

The large volumetric expansion of conversion-type anode materials (CTAMs) based on transition-metal oxides is still a big challenge for lithium-ion batteries (LIBs). An obtained nanocomposite was established by tin oxide (SnO₂) nanoparticles embedding in cellulose nanofiber (SnO₂-CNFi), and was developed in our research to take advantage of the tin oxide's high theoretical specific capacity and the cellulose nanofiber support structure to restrain the volume expansion of transition-metal oxides. The nanocomposite utilized as electrodes in lithium-ion batteries not only inhibited volume growth but also contributed to enhancing electrode electrochemical performance, resulting in the good capacity maintainability of the LIBs electrode during the cycling process. The SnO₂-CNFi nanocomposite electrode delivered a specific discharge capacity of 619 mAh g^-1 after 200 working cycles at the current rate of 100 mA g^-1. Moreover, the coulombic efficiency remained above 99% after 200 cycles showing the good stability of the electrode, and promising potential for commercial activity of nanocomposites electrode.

Nano-Confined Tin Oxide in Carbon Nanotube Electrodes via Electrostatic Spray Deposition for Lithium-Ion Batteries

The development of novel materials is essential for the next generation of electric vehicles and portable devices. Tin oxide (SnO2), with its relatively high theoretical capacity, has been considered as a promising anode material for applications in energy storage devices. However, the SnO2 anode material suffers from poor conductivity and huge volume expansion during charge/discharge cycles. In this study, we evaluated an approach to control the conductivity and volume change of SnO2 through a controllable and effective method by confining different percentages of SnO2 nanoparticles into carbon nanotubes (CNTs). The binder-free confined SnO2 in CNT composite was deposited via an electrostatic spray deposition technique. The morphology of the synthesized and deposited composite was evaluated by scanning electron microscopy and high-resolution transmission electron spectroscopy. The binder-free 20% confined SnO2 in CNT anode delivered a high reversible capacity of 770.6 mAh g-1. The specific capacity of the anode increased to 1069.7 mAh g-1 after 200 cycles, owing to the electrochemical milling effect. The delivered specific capacity after 200 cycles shows that developed novel anode material is suitable for lithium-ion batteries (LIBs).

Titanium dioxide-based anode materials for lithium-ion batteries: structure and synthesis

Lithium-ion batteries (LIBs) have high energy density, long life, good safety, and environmental friendliness, and have been widely used in large-scale energy storage and mobile electronic devices. As a cheap and non-toxic anode material for LIBs, titanium dioxide (TiO2) has a good application prospect. However, its poor electrical conductivity leads to unsatisfactory electrochemical performance, which limits its large-scale application. In this review, the structure of three TiO2 polymorphs which are widely investigated are briefly described, then the preparation and electrochemical performance of TiO2 with different morphologies, such as nanoparticles, nanowires, nanotubes, and nanospheres, and the related research on the TiO2 composite materials with carbon, silicon, and metal materials are discussed. Finally, the development trend of TiO2-based anode materials for LIBs has been briefly prospected.

Metal oxide nanocomposite based flexible nanogenerator: synergic effect of light and pressure

Here, we report the fabrication of nanocomposite comprising of CuO and poly (vinylidene fluoride-hexafluoro propylene) (PVDF-HFP) for application in flexible piezoelectric nanogenerators (PENG). The chemically grown CuO nanostructures have been characterized through electron microscopy, x-ray diffraction, and spectroscopic techniques. It has been found that the incorporation of optimal CuO nanostructures in PVDF-HFP can increase the output voltage of the PENG by 22 times and is assigned to the increment in the effective dielectric constant of host PVDF-HFP. Further, the nanogenerator exhibits a maximum power of ∼20μW cm^-2at 3 MΩ load and can charge a capacitor under continuous bio-mechanical impart. Further, upon slight alteration of the device configuration, the output of the nanocomposite-based nanogenerator can be enhanced under illumination condition. The increment in overall piezopotential through photoexcitation in optically active CuO nanostructures can be assigned to the increment in output voltage. The wavelength dependent output variation reveal the maximum output of the PENG under blue light. Further, under white light illumination, the nanogenerator exhibits a maximum power which is 3 times higher than in dark condition and can charge a capacitor 52 times faster. The development of such superior flexible and optically active nanogenerators are quite promising for futuristic self-powered devices operated under mechanical and solar energies.

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.

Review of metal oxides as anode materials for lithium-ion batteries

Lithium-ion batteries with a stable circulation capacity, high energy density and good safety are widely used in automobiles, mobile phones, manufacturing and other fields. MOs due to their large theoretical capacity, simple processing and abundant reserves, and used as anode materials for LIBs, have attracted much attention. Three electrochemical mechanisms of MOs are reviewed in this paper. In addition, research progress of MOs and prospects for their further applications in LIBs are summarized.

Zn-doped Tin monoxide nanobelt induced engineering a graphene and CNT supported Zn-doped Tin dioxide composite for Lithium-ion storage

In this work, a rapid coprecipitation reaction is developed to obtain nano-sized Zn-doped tin oxide samples (Zn-SnO-II or Zn-SnO₂-IV) for the first time by simply mixing tin ion (Sn²⁺ or Sn⁴⁺) and zinc ion (Zn²⁺) containing salts in a mild aqueous condition. Characterization results illustrate the Zn-SnO-II sample is constituted by an overwhelming quantity of Zn-doped SnO nanobelts and a small quantity of Zn-doped SnO₂ nanoparticles. The redox reaction between the Sn²⁺ ions from the Zn-SnO-II sample and the surface oxygen-containing functional groups from functionalized carbon nanotube (F-CNT) and graphene oxide (GO) leads to the formation of the final Zn-SnO₂/CNT@RGO composites. As an anode active material for lithium-ion batteries, the Zn-SnO₂/CNT@RGO product showed superior electrochemical performance than the controlled Zn-SnO₂/CNT and Zn-SnO₂/RGO samples, which had a high gravimetric capacity of 901.3 mAh·g^-1 at a high charge and discharge current of 1000 mA·g^-1 after 300 cycles and excellent rate capability. The reaction mechanism for the successful synthesis of the Zn-doped tin oxide samples has been proposed, and the insight into the outstanding lithium-ion storage performance for the Zn-SnO₂/CNT@RGO composite has been revealed. The synthetic processes for both the Zn-doped tin oxides and derived carbon supported composites are straightforward and involve no harsh conditions nor complicated treatment, which have good potential for massive production and application in wider fields.

Ultrafine SnO2/Sn Nanoparticles Embedded into an In Situ Generated Meso-/Macroporous Carbon Matrix with a Tunable Pore Size

Ultrafine SnO₂/Sn nanoparticles encapsulated into an adjustable meso-/macroporous carbon matrix have been successfully fabricated by the in situ SiO_x sacrificial strategy. The control over the void space in the carbon matrix effectively improves the accessibility of the SnO₂/Sn toward an electrolyte solution. More importantly, the void space also provides an efficient means to accommodate the mechanical stress caused by the volume change of the SnO₂/Sn over cycles. As a result, the enhanced electrolyte accessibility and suppressed mechanical stress improve the electrochemical performance regarding reversible capacity, cyclic stability, and rate capability. A reversible capacity of 1105 mAh g^-1 is still retained after 290 cycles at 200 mAg^-1, and the capacity still can keep at 107 mAh g^-1 at a high current density of 10 A g^-1.

Tin-Based Anode Materials for Stable Sodium Storage: Progress and Perspective

Because of concerns regarding shortages of lithium resources and the urgent need to develop low-cost and high-efficiency energy-storage systems, research and applications of sodium-ion batteries (SIBs) have re-emerged in recent years. Herein, recent advances in high-capacity Sn-based anode materials for stable SIBs are highlighted, including tin (Sn) alloys, Sn oxides, Sn sulfides, Sn selenides, Sn phosphides, and their composites. The reaction mechanisms between Sn-based materials and sodium are clarified. Multiphase and multiscale structural optimizations of Sn-based materials to achieve good sodium-storage performance are emphasized. Full-cell designs using Sn-based materials as anodes and further development of Sn-based materials are discussed from a commercialization perspective. Insights into the preparation of future high-performance Sn-based anode materials and the construction of sodium-ion full batteries with a high energy density and long service life are provided.

Recent insights into SnO2-based engineered nanoparticles for sustainable H2 generation and remediation of pesticides

Due to the ongoing industrial revolution and global health pandemics, solar-driven water splitting and pesticide degradation are highly sought to cope with catastrophes such as depleting fossil reservoirs, global warming, and environmental degradation.

Porous carbon-confined Co x S y nanoparticles derived from ZIF-67 for boosting lithium-ion storage

Reasonable regulation and synthesis of hollow nanostructure materials can provide a promising electrode material for lithium-ion batteries (LIBs). In this work, utilizing a metal-organic framework (MOF, ZIF-67) as the raw material and template, a composite of Co x S y with a carbon shell is successfully formed through a hydrothermal vulcanization and a subsequent high temperature sintering process. The as-obtained Co x S y (700) material sintered at 700 °C has a large specific surface area, and at the same time possesses a hollow carbon shell structure. Benefiting from unique structural advantages, the volume change during the electrochemical reaction can be well alleviated, and thus the structural stability is greatly improved. The presence of the carbon matrix can also offer sufficient ion/electron transfer channels, contributing to the enhanced electrochemical performance. As a result, the Co x S y (700) electrode can deliver an excellent capacity of 875.6 mA h g-1 at a current density of 100 mA g-1. Additionally, a high-capacity retention of 88% is achieved after 1000 cycles when the current density is increased to 500 mA g-1, and exhibiting a prominent rate capability of 526.5 mA h g-1, simultaneously. The novel synthesis route and considerable electrochemical properties presented by this study can afford guidance for the exploration of high-performance cobalt sulfide anodes in LIBs.

Boosting the lithium storage performance of tin dioxide by carbon nanotubes supporting and surface engineering

In order to reduce the negative impact of the extra carbon coating on the electrochemical properties of the commonly sandwiched carbon nanotubes@tin dioxide@carbon (CNT@SnO₂@C) composites, the external C coating has been designed as a porous carbon in this work. The well-designed porous carbon coating offers an attractive advantage compared to the common carbon coatings, namely, it can not only better mitigate the volumetric variation of SnO₂ by means of its spongy structure with better flexibility and rich free space, but also accelerate the lithium-ions diffusion by virtue of its open tunnel-like architecture. For this reason, this composite prepared here shows outstanding electrochemical performance stemming from the cooperative effect of inner CNT supporting and externally porous carbon coating, displaying 819.3 and 576.0 mAh g^-1 at 200 and even 1000 mA g^-1 after even 500 cycles, respectively. This surface engineering strategy may be valuable for enhancing the cyclical durability of other metal oxides with higher theoretical specific capacities.

Shaping Tin Nanocomposites through Transient Local Conversion Reactions

Shape-preserving conversion offers a promising strategy to transform self-assembled structures into advanced functional components with customizable composition and shape. Specifically, the assembly of barium carbonate nanocrystals and amorphous silica nanocomposites (BaCO₃/SiO₂) offers a plethora of programmable three-dimensional (3D) microscopic geometries, and the nanocrystals can subsequently be converted into functional chemical compositions, while preserving the original 3D geometry. Despite this progress, the scope of these conversion reactions has been limited by the requirement to form carbonate salts. Here, we overcome this limitation using a single-step cation/anion exchange that is driven by the temporal pH change at the converting nanocomposite. We demonstrate the proof of principle by converting BaCO₃/SiO₂ nanocomposites into tin-containing nanocomposites, a metal without a stable carbonate. We find that BaCO₃/SiO₂ nanocomposites convert in a single step into hydroromarchite nanocomposites (Sn₃(OH)₂O₂/SiO₂) with excellent preservation of the 3D geometry and fine features. We explore the versatility and tunability of these Sn₃(OH)₂O₂/SiO₂ nanocomposites as a precursor for functional compositions by developing shape-preserving conversion routes to two desirable compositions: tin perovskites (CH₃NH₃SnX₃, with X = I or Br) with tunable photoluminescence (PL) and cassiterite (SnO₂)-a widely used transparent conductor. Ultimately, these findings may enable integration of functional chemical compositions into advanced morphologies for next-generation optoelectronic devices.

Facile Synthesis of MPS3/C (M = Ni and Sn) Hybrid Materials and Their Application in Lithium-Ion Batteries

Herein, we successfully synthesized two novel metal thiophosphites (MTPs) hybridized with carbon, that is, NiPS3/C and SnPS3/C composites, via an environment-friendly and cost-effective approach without harsh reaction conditions. Subsequently, the electrochemical performances of NiPS3/C and SnPS3/C composites have been investigated in coin-cells, and it is revealed that MTPs/C have a significantly higher Li-storage capacity and better stability compared to the MTPs without carbon. Moreover, the SnPS3/C electrode shows a lower internal resistance and a better rate performance compared to NiPS3/C. We employed extensive ex situ experiments to characterize the materials and interpreted the remarkably improved performance of MTPs/C.

A comparative study of the photoelectric properties for lithium oxide prepared by Green synthesis method

Lithium oxide Li2O was synthesized by two green synthesis methods using two plants saffron and turmeric. Then the Li2O colloidal is deposite on p-type porous Si substrate p-PSi and n-type porous silicon substrate n-PSi to fabricate Al/Li2O/p-PSi/pSi/Al heterojunction and Al/Li2O/n-Psi/nSi/Al heterojunction. The morphological studies were measured by X-Ray Diffraction XRD getting an average crystallite size 34.7 nm for green synthesized saffron and 31.36 nm average crystallite size in case of green synthesized turmeric. Scanning Electron Microscopy SEM was about 80 nm size in case of saffron and about 55 nm. Fourier Transformation Infra-Red FT-IR was nearly the same in both cases. Optical measurement UV-visible occurred by calculating the transmittance and absorbance spectra and finally IV-in dark and IV under illumination were measured for the application of a heterojunction as a solar cell.

MOF derived double-carbon layers boosted the lithium/sodium storage performance of SnO2nanoparticles

Tin oxide (SnO₂) was considered as a promising alternative to commonly used graphite anode in energy storage devices thanks to its superior specific capacity. However, its electrochemical property was severely limited due to the inherent poor conductivity and drastic volume variation during the charging/discharging process. To overcome this disadvantage, we grew Sn-MOF directly on graphene oxide (GO) layers to synthesize a double carbon conductive network-encapsulated SnO₂nanoparticles (SnO₂/C/rGO) via a facile solvothermal method. During the process, Sn-MOF skeleton transformed into porous carbon shells, in which nanosized SnO₂particles (~8nm) were embedded, while GO template was reduced to highly conductive rGO layer tightly wrapping the SnO₂/C particles. This double-carbon structure endowed SnO₂/C/rGO anode with enhanced specific capacity and rate property both in lithium ion batteries (LIB) and sodium ion batteries (SIB). The SnO₂/C/rGO anode showed a highly reversible specific capacity of 1038.3 mAh g^-1at 100 mA g^-1, and maintained a stable capacity of 720.2 mAh g^-1(70.1%) under 500 mA g^-1after 150 cycles in LIBs. Similarly, highly reversible capacity of 350.7 mAh g^-1(81.1%) under 100 mA g^-1after 150 cycles was also achieved in SIBs. This work provided a promising strategy in improving the electrochemical properties of SnO₂nanoparticles (NPs), as well as other potential anode materials suffering from huge volume change and poor conductivity.

Superior Room-Temperature Ammonia Sensing Using a Hydrothermally Synthesized MoS2/SnO2 Composite

Layered two-dimensional transition metal dichalcogenides, due to their semiconducting nature and large surface-to-volume ratio, have created their own niche in the field of gas sensing. Their large recovery time and accompanied incomplete recovery result in inferior sensing properties. Here, we report a composite-based strategy to overcome these issues. In this study, we report a facile double-step synthesis of a MoS₂/SnO₂ composite and its successful use as a superior room-temperature ammonia sensor. Contrary to the pristine nanosheet-based sensors, the devices made using the composite display superior gas sensing characteristics with faster response. Specifically, at room temperature (30° C), the composite-based sensor exhibited excellent sensitivity (10%) at an ammonia concentration down to 0.4 ppm along with the response and recovery times of 2 and 10 s, respectively. Moreover, the device also exhibited long-term durability, reproducibility, and selectivity toward ammonia against hydrogen sulfide, methanol, ethanol, benzene, acetone, and formaldehyde. Sensor devices made on quartz and alumina substrates with different roughnesses have yielded almost an identical response, except for slight variations in response and recovery transients. Further, to shed light on the underlying adsorption energetics and selectivity, density functional theory simulations were employed. The improved response and enhanced selectivity of the composite were explicitly discussed in terms of adsorption energy. Lowdin charge analysis was performed to understand the charge transfer mechanism between NH₃, H₂S, CH₃OH, HCHO, and the underlying MoS₂/SnO₂ composite surface. The long-term durability of the sensor was evident from the stable response curves even after 2 months. These results indicate that hydrothermally synthesized MoS₂/SnO₂ composite-based gas sensors can be used as a promising sensing material for monitoring ammonia gas in real fields.

In Situ Local Oxidation of SnO Induced by Laser Irradiation: A Stability Study

In this work, semiconductor tin oxide (II) (SnO) nanoparticles and plates were synthesized at room conditions via a hydrolysis procedure. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the high crystallinity of the as-synthesized romarchite SnO nanoparticles with dimensions ranging from 5 to 16 nm. The stability of the initial SnO and the controlled oxidation to SnO2 was studied based on either thermal treatments or controlled laser irradiation using a UV and a red laser in a confocal microscope. Thermal treatments induced the oxidation from SnO to SnO2 without formation of intermediate SnOx, as confirmed by thermodiffraction measurements, while by using UV or red laser irradiation the transition from SnO to SnO2 was controlled, assisted by formation of intermediate Sn3O4, as confirmed by Raman spectroscopy. Photoluminescence and Raman spectroscopy as a function of the laser excitation source, the laser power density, and the irradiation duration were analyzed in order to gain insights in the formation of SnO2 from SnO. Finally, a tailored spatial SnO/SnO2 micropatterning was achieved by controlled laser irradiation with potential applicability in optoelectronics and sensing devices.

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO2@MXene lithium ion anode system

Structural and chemical interplay between nano-active and encapsulation materials in a core–shell SnO₂@MXene lithium ion anode system was investigated in detail.

Dual Immobilization of SnOx Nanoparticles by N-Doped Carbon and TiO2 for High-Performance Lithium-Ion Battery Anodes

The grain aggregation engendered kinetics failure is regarded as the main reason for the electrochemical decay of nanosized anode materials. Herein, we proposed a dual immobilization strategy to suppress the migration and aggregation of SnO_x nanoparticles and corresponding lithiation products through constructing SnO_x/TiO₂@PC composites. The N-doped carbon could anchor the tin oxide particles and inhibit their aggregation during the preparation process, leading to a uniform distribution of ultrafine SnO_x nanoparticles in the matrix. Meanwhile, the incorporated TiO₂ component works as parclose to suppress the migration and coarsening of SnO_x and corresponding lithiation products. In addition, the N-doped carbon and TiO₂/Li_xTiO₂ can significantly improve the electrical and ionic conductivities of the composites, enabling a good diffusion and charge-transfer dynamics. Owing to the dual immobilization from the "synergistic effect" of N-doped carbon and the "parclose effect" of TiO₂, the conversion reaction of SnO_x remains fully reversible throughout the cycling. Thereby, the composites exhibit excellent cycling performance in half cells and can be fully utilized in full cells. This work may provide an inspiration for the rational design of tin-based anodes for high-performance lithium-ion batteries.

Mo-Doped SnO2 Nanoparticles Embedded in Ultrathin Graphite Nanosheets as a High-Reversible-Capacity, Superior-Rate, and Long-Cycle-Life Anode Material for Lithium-Ion Batteries

A new ternary Mo-SnO₂-graphite composite has been constructed via hydrothermal and ball milling. The Mo/SnO₂ hybrids were homogeneously dispersed in graphite nanosheets. In the Mo-SnO₂-graphite, Mo can inhibit the Sn nanoparticle aggregation, enhance the reversible conversion reaction in lithiation, and improve the electrochemical performance. Consequently, the Mo-SnO₂-graphite composite contributes a high capacity of 1317.4 mAh g^-1 at 0.2 A g^-1 after 200 cycles, remarkable rate property of 514.0 mAh g^-1 at 5 A g^-1, and long-term cyclic stabilization of 759.0 mAh g^-1 after 950 cycles at 1.0 A g^-1. With outstanding electrochemical performance and facial synthesis, the ternary Mo-SnO₂-graphite is a hopeful anode material for lithium-ion batteries (LIBs).

SnO2 Nanoflower-Nanocrystalline Cellulose Composites as Anode Materials for Lithium-Ion Batteries

One of the biggest challenges in the commercialization of tin dioxide (SnO₂₎-based lithium-ion battery (LIB) electrodes is the volume expansion of SnO₂ during the charge-discharge process. Additionally, the aggregation of SnO₂ also deteriorates the performance of anode materials. In this study, we prepared SnO₂ nanoflowers (NFs) using nanocrystalline cellulose (CNC) to improve the surface area, prevent the particle aggregation, and alleviate the change in volume of LIB anodes. Moreover, CNC served not only as the template for the synthesis of the SnO₂ NFs but also as a conductive material, after annealing the SnO₂ NFs at 800 °C to improve their electrochemical performance. The obtained CNC-SnO₂NF composite was used as an active LIB electrode material and exhibited good cycling performance and a high initial reversible capacity of 891 mA h g^-1, at a current density of 100 mA g^-1. The composite anode could retain 30% of its initial capacity after 500 charge-discharge cycles.

Controlled Prelithiation of SnO2/C Nanocomposite Anodes for Building Full Lithium-Ion Batteries

SnO₂ is an attractive anodic material for advanced lithium-ion batteries (LIBs). However, its low electronic conductivity and large volume change in lithiation/delithiation lead to a poor rate/cycling performance. Moreover, the initial Coulombic efficiencies (CEs) of SnO₂ anodes are usually too low to build practical full LIBs. Herein, a two-step hydrothermal synthesis and pyrolysis method is used to prepare a SnO₂/C nanocomposite, in which aggregated SnO₂ nanosheets and a carbon network are well-interpenetrated with each other. The SnO₂/C nanocomposite exhibits a good rate/cycling performance in half-cell tests but still shows a low initial CE of 45%. To overcome this shortage and realize its application in a full-cell assembly, the SnO₂/C anode is controllably prelithiated by the lithium-biphenyl reagent and then coupled with a LiCoO₂ cathode. The resulting full LIB displays a high capacity of over 98 mAh g^-1_LCO in 300 cycles at 1 C rate.

Heteroleptic Tin(IV) Aminoalkoxides and Aminofluoroalkoxides as MOCVD Precursors for Undoped and F-Doped SnO2 Thin Films

A series of asymmetric and potentially bidentate amino alcohols and amino fluoro alcohols (R_NOH) having a different number of methyl/trifluoromethyl substituents at the α-carbon atom, [HOC(R¹)(R²)CH₂NMe₂] (R¹ = R² = H (dmaeH); R¹ = H, R² = CH₃ (dmapH); R¹ = R² = CH₃ (dmampH); R¹ = H, R² = CF₃ (F-dmapH); R¹ = R² = CF₃ (F-dmampH)) have been used to develop new monomeric and heteroleptic tin(IV) amino(fluoro)alkoxides [Sn(OR)₂(OR_N)₂] (R = Et, Prⁱ, Bu^t). These new complexes, which were thoroughly characterized by spectroscopy (IR and multinuclei NMR (¹H, ¹³C, ¹⁹F, and ¹¹⁹Sn)) as well as single-crystal X-ray studies on representative samples, were investigated for their thermal behavior to determine their suitability as MOCVD precursors for the deposition of metal oxide thin films. The two most suitable compounds, [Sn(OBu^t)₂(dmamp)₂] and [Sn(OBu^t)₂(F-dmamp)₂], were used in a direct liquid injection chemical vapor deposition (DLI-CVD) process to deposit undoped SnO₂ and F-doped SnO₂ thin films, respectively, on silicon and quartz substrates. Film growth rates at different temperatures (from 400 to 700 °C), film thickness, crystalline quality, and surface morphology were investigated. The films deposited on quartz showed high transparency (above 80%) in the visible region and low carbon contamination on the surface (11-13% from XPS), which could easily be removed completely with 2 min of Ar⁺ sputtering.

High Na+ Mobility in rGO Wrapped High Aspect Ratio 1D SbSe Nano Structure Renders Better Electrochemical Na+ Battery Performance

We chose to understand the cyclic instability and rate instability issues in the promising class of Na⁺ conversion and alloying anodes with Sb₂ Se₃ as a typical example. We employ a synthetic strategy that ensures efficient rGO (reduced graphene oxide) wrapping over Sb₂ Se₃ material. By utilization of the minimum weight of additive (5 wt.% of rGO), we achieved a commendable performance with a reversible capacity of 550 mAh g^-1 at a specific current of 100 mA g^-1 and an impressive rate performance with 100 % capacity retention after high current cycling involving a 2 Ag^-1 intermediate current step. The electrochemical galvanostatic intermittent titration technique (GITT) has been employed for the first time to draw a rationale between the enhanced performance and the increased mobility in the rGO wrapped composite (Sb₂ Se₃ -rGO) compared to bare Sb₂ Se₃ . GITT analysis reveals higher Na⁺ diffusion coefficients (approx. 30 fold higher) in the case of Sb₂ Se₃ -rGO as compared to bare Sb₂ Se₃ throughout the operating voltage window. For Sb₂ Se₃ -rGO the diffusion coefficients in the range of 8.0×10^-15  cm²  s^-1 to 2.2×10^-12  cm²  s^-1 were observed, while in case of bare Sb₂ Se₃ the diffusion coefficients in the range of 1.6×10^-15  cm²  s^-1 to 9.4×10^-15  cm²  s^-1 were observed.

Ordered SnO2 nanotube arrays of tuneable geometry as a lithium ion battery material with high longevity

Ordered arrays of straight, parallel SnO₂ nanotubes are prepared by atomic layer deposition (ALD) on inert 'anodic' aluminum oxide porous membranes serving as templates. Various thicknesses of the SnO₂ tube walls and various tube lengths are characterized in terms of morphology by scanning electron microscopy (SEM), chemical identity by X-ray photoelectron spectroscopy (XPS) and phase composition by X-ray diffraction (XRD). Their performance as negative electrode ('anode') materials for lithium-ion batteries (LIBs) is quantified at different charge and discharge rates in the absence of additives. We find distinct trends and optima for the dependence of initial capacity and long-term stability on the geometric parameters of the nanotube materials. A sample featuring SnO₂ tubes of 30 µm length and 10 nm wall thickness achieves after 780 cycles a coulombic efficiency of >99% and a specific capacity of 671 mA h g^-1. This value represents 92% of the first-cycle capacity and 86% of the theoretical value.

Comparative study of the implementation of tin and titanium oxide nanoparticles as electrodes materials in Li-ion batteries

Transition metal oxides potentially present higher specific capacities than the current anodes based on carbon, providing an increasing energy density as compared to commercial Li-ion batteries. However, many parameters could influence the performance of the batteries, which depend on the processing of the electrode materials leading to different surface properties, sizes or crystalline phases. In this work a comparative study of tin and titanium oxide nanoparticles synthesized by different methods, undoped or Li doped, used as single components or in mixed ratio, or alternatively forming a composite with graphene oxide have been tested demonstrating an enhancement in capacity with Li doping and better cyclability for mixed phases and composite anodes.

Tin and Tin Compound Materials as Anodes in Lithium-Ion and Sodium-Ion Batteries: A Review

Tin and tin compounds are perceived as promising next-generation lithium (sodium)-ion batteries anodes because of their high theoretical capacity, low cost and proper working potentials. However, their practical applications are severely hampered by huge volume changes during Li⁺ (Na⁺) insertion and extraction processes, which could lead to a vast irreversible capacity loss and short cycle life. The significance of morphology design and synergic effects-through combining compatible compounds and/or metals together-on electrochemical properties are analyzed to circumvent these problems. In this review, recent progress and understanding of tin and tin compounds used in lithium (sodium)-ion batteries have been summarized and related approaches to optimize electrochemical performance are also pointed out. Superiorities and intrinsic flaws of the above-mentioned materials that can affect electrochemical performance are discussed, aiming to provide a comprehensive understanding of tin and tin compounds in lithium(sodium)-ion batteries.