TiO2 Hollow Spheres With Flower-Like SnO2 Shell as Anodes for Lithium-Ion Batteries

SnO₂ is a promising anode material for lithium-ion batteries due to its high theoretical specific capacity and low operation voltage. However, its poor cycling performance hinders its commercial application. In order to improve the cycling stability of SnO₂ electrodes, novel flower-like SnO₂/TiO₂ hollow spheres were prepared by facile hydrothermal method using carbon spheres as templates. Their flower-like shell and mesoporous structure highlighted a large specific surface area and excellent ion migration performance. Their TiO₂ hollow sphere matrix and 2D SnO₂ nano-flakes ensured good cycle stability. The electrochemical measurements indicated that novel flower-like SnO₂/TiO₂ hollow spheres delivered a high specific capacity, low irreversible capacity loss and superior rate performance. After 1,000 cycles at current densities of 200 mA g⁻¹, the capacity of the flower-like SnO₂/TiO₂ hollow spheres was still maintained at 720 mAh g⁻¹. Their rate capacity reached 486 mAh g⁻¹ when the current densities gradually increase to 2,000 mA g⁻¹.

Tin dioxide-based nanomaterials as anodes for lithium-ion batteries

The development of new electrode materials for lithium-ion batteries (LIBs) has attracted significant attention because commercial anode materials in LIBs, like graphite, may not be able to meet the increasing energy demand of new electronic devices. Tin dioxide (SnO2) is considered as a promising alternative to graphite due to its high specific capacity. However, the large volume changes of SnO2 during the lithiation/delithiation process lead to capacity fading and poor cycling performance. In this review, we have summarized the synthesis of SnO2-based nanomaterials with various structures and chemical compositions, and their electrochemical performance as LIB anodes. This review addresses pure SnO2 nanomaterials, the composites of SnO2 and carbonaceous materials, the composites of SnO2 and transition metal oxides, and other hybrid SnO2-based materials. By providing a discussion on the synthesis methods and electrochemistry of some representative SnO2-based nanomaterials, we aim to demonstrate that electrochemical properties can be significantly improved by modifying chemical composition and morphology. By analyzing and summarizing the recent progress in SnO2 anode materials, we hope to show that there is still a long way to go for SnO2 to become a commercial LIB electrode and more research has to be focused on how to enhance the cycling stability.

Germanium tin alloy nanowires as anode materials for high performance Li-ion batteries

The combination of two active Li-ion materials (Ge and Sn) can result in improved conduction paths and higher capacity retention. Here we report for the first time, the implementation of Ge_1-x Sn _x alloy nanowires as anode materials for Li-ion batteries. Ge_1-x Sn _x alloy nanowires have been successfully grown via vapor-liquid-solid technique directly on stainless steel current collectors. Ge_1-x Sn _x (x = 0.048) nanowires were predominantly seeded from the Au_0.80Ag_0.20 catalysts with negligible amount of growth was also directly catalyzed from stainless steel substrate. The electrochemical performance of the the Ge_1-x Sn _x nanowires as an anode material for Li-ion batteries was investigated via galvanostatic cycling and detailed analysis of differential capacity plots (DCPs). The nanowire electrodes demonstrated an exceptional capacity retention of 93.4% from the 2nd to the 100th charge at a C/5 rate, while maintaining a specific capacity value of ∼921 mAh g^-1 after 100 cycles. Voltage profiles and DCPs revealed that the Ge_1-x Sn _x nanowires behave as an alloying mode anode material, as reduction/oxidation peaks for both Ge and Sn were observed, however it is clear that the reversible lithiation of Ge is responsible for the majority of the charge stored.

Low-Temperature Growing Anatase TiO2/SnO2 Multi-dimensional Heterojunctions at MXene Conductive Network for High-Efficient Perovskite Solar Cells

A multi-dimensional conductive heterojunction structure, composited by TiO2, SnO2, and Ti3C2TX MXene, is facilely designed and applied as electron transport layer in efficient and stable planar perovskite solar cells. Based on an oxygen vacancy scramble effect, the zero-dimensional anatase TiO2 quantum dots, surrounding on two-dimensional conductive Ti3C2TX sheets, are in situ rooted on three-dimensional SnO2 nanoparticles, constructing nanoscale TiO2/SnO2 heterojunctions. The fabrication is implemented in a controlled low-temperature anneal method in air and then in N2 atmospheres. With the optimal MXene content, the optical property, the crystallinity of perovskite layer, and internal interfaces are all facilitated, contributing more amount of carrier with effective and rapid transferring in device. The champion power conversion efficiency of resultant perovskite solar cells achieves 19.14%, yet that of counterpart is just 16.83%. In addition, it can also maintain almost 85% of its initial performance for more than 45 days in 30-40% humidity air; comparatively, the counterpart declines to just below 75% of its initial performance.

Electronic and magnetic properties of SnSe monolayers doped by Ga, In, As, and Sb: a first-principles study

A SnSe monolayer with an orthorhombic Pnma GeS structure is an important two-dimensional (2D) indirect band gap material at room temperature. Based on first-principles density functional theory calculations, we present systematic studies on the electronic and magnetic properties of X (X = Ga, In, As, Sb) atom doped SnSe monolayers. The calculated electronic structures show that the Ga-doped system maintains its semiconducting properties while the In-doped SnSe monolayer is half-metal. The As- and Sb-doped SnSe systems present the characteristics of an n-type semiconductor. Moreover, all considered substitutional doping cases induce magnetic ground states with a magnetic moment of ∼ 1 μB. In addition, the calculated formation energies also show that four types of doped systems are thermodynamically stable. These results provide a new route for the potential applications of doped SnSe monolayers in 2D photoelectronic and magnetic semiconductor devices.

Nanotubular Heterostructure of Tin Dioxide/Titanium Dioxide as a Binder-Free Anode in Lithium-Ion Batteries

Titanium dioxide (TiO2 ), tin dioxide (SnO2 ), and heterostructured TiO2 /SnO2 nanotube (NT) arrays have been fabricated by template-assisted atomic-layer deposition (ALD) for use as anodes in a lithium-ion battery (LIB). TiO2 NT arrays with 8 nm thick walls showed higher capacity (≈250 mA h g(-1) after the 50th cycle at a rate of C/10) than the typical theoretical capacity of bulk TiO2 and a radically improved capacity retention property upon cycling. SnO2 NT arrays with different wall thicknesses (8, 10, 13, and 20 nm) were also fabricated and their electrochemical performances were measured. All of the SnO2 NT arrays showed substantially higher initial irreversible capacity and higher reversible capacity than those of bulk TiO2 . Thinner walls of the SnO2 NTs result in better capacity retention. Heterotubular structures of TiO2 (5 nm)/SnO2 (10 nm)/TiO2 (5 nm) were successfully fabricated, and displayed a sufficiently high capacity (≈300 mA h g(-1) after 50 cycles) with exceptionally improved cycling performance up to the 50th cycle.

Ternary Sn-Ti-O based nanostructures as anodes for lithium ion batteries

SnO(x) (x = 0, 1, 2) and TiO(2) are widely considered to be potential anode candidates for next generation lithium ion batteries. In terms of the lithium storage mechanisms, TiO(2) anodes operate on the base of the Li ion intercalation-deintercalation, and they typically display long cycling life and high rate capability, arising from the negligible cell volume change during the discharge-charge process, while their performance is limited by low specific capacity and low electronic conductivity. SnO(x) anodes rely on the alloying-dealloying reaction with Li ions, and typically exhibit large specific capacity but poor cycling performance, originating from the extremely large volume change and thus the resultant pulverization problems. Making use of their advantages and minimizing the disadvantages, numerous strategies have been developed in the recent years to design composite nanostructured Sn-Ti-O ternary systems. This Review aims to provide rational understanding on their design and the improvement of electrochemical properties of such systems, including SnO(x) -TiO(2) nanocomposites mixing at nanoscale and nanostructured Sn(x) Ti(1-x) O(2) solid solutions doped at the atomic level, as well as their combinations with carbon-based nanomaterials.

An Fe3O4@(C–MnO2) core–double-shell composite as a high-performance anode material for lithium ion batteries

An Fe₃O₄@(C–MnO₂) composite with a cube-like core–double-shell structure has been successfully prepared as an anode material.

Hydrothermal synthesis and electrochemical properties of tin titanate nanowires coupled with SnO2 nanoparticles for Li-ion batteries

Tin-titanate nanowires coupled with SnO₂ nanoparticles demonstrate enhanced electrochemical properties owing to atomic- and nano-scaled uniform distribution of tin elements.

SnO2@TiO2 double-shell nanotubes for a lithium ion battery anode with excellent high rate cyclability

SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

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

The development of new electrode materials for lithium-ion batteries (LIBs) has always been a focal area of materials science, as the current technology may not be able to meet the high energy demands for electronic devices with better performance. Among all the metal oxides, tin dioxide (SnO₂) is regarded as a promising candidate to serve as the anode material for LIBs due to its high theoretical capacity. Here, a thorough survey is provided of the synthesis of SnO₂-based nanomaterials with various structures and chemical compositions, and their application as negative electrodes for LIBs. It covers SnO₂ with different morphologies ranging from 1D nanorods/nanowires/nanotubes, to 2D nanosheets, to 3D hollow nanostructures. Nanocomposites consisting of SnO₂ and different carbonaceous supports, e.g., amorphous carbon, carbon nanotubes, graphene, are also investigated. The use of Sn-based nanomaterials as the anode material for LIBs will be briefly discussed as well. The aim of this review is to provide an in-depth and rational understanding such that the electrochemical properties of SnO₂-based anodes can be effectively enhanced by making proper nanostructures with optimized chemical composition. By focusing on SnO₂, the hope is that such concepts and strategies can be extended to other potential metal oxides, such as titanium dioxide or iron oxides, thus shedding some light on the future development of high-performance metal-oxide based negative electrodes for LIBs.

Layer-by-layer synthesis of γ-Fe2O3@SnO2@C porous core-shell nanorods with high reversible capacity in lithium-ion batteries

We demonstrated the layer-by-layer synthesis of γ-Fe2O3@SnO2@C porous core-shell nanorods. FeOOH nanorods were first synthesized via a hydrothermal process, and acted as a template for subsequent layer-by-layer deposition. It was indicated that the electrostatic attraction between the charged species may play the key role in the formation of the core-shell nanostructures. When used as an anode material in lithium-ion batteries, γ-Fe2O3@SnO2@C porous core-shell nanorods showed high initial Coulombic efficiency, high reversible capacity, and good cycling and rate performances. The correlation between the structure, composition and electrochemical performance was also discussed.