Preparation of a porous Sn@C nanocomposite as a high-performance anode material for lithium-ion batteries

MOF-derived porous carbon nanofibers wrapping Sn nanoparticles as flexible anodes for lithium/sodium ion batteries

Facile synthesis of flexible electrodes with high reversible capacity plays a key role in meeting the ever-increasing demand for flexible batteries. Herein, we incorporated Sn-based metal-organic framework (Sn-MOF) templates into crosslinked one-dimensional carbon nanofibers (CNFs) using an electrospinning strategy and obtained a hierarchical porous film (Sn@C@CNF) after a carbothermal reduction reaction. Merits of this modification strategy and its mechanism in improving the electrochemical performance of Sn nanoparticles (NPs) were revealed. Electrospun CNFs substrate ensured a highly conductive skeleton and excellent mechanical toughness, making Sn@C@CNF a self-supported binder-free electrode. Serving as a self-sacrificing template, Sn-MOF provided Sn NPs and derived into porous structures on CNFs after pyrolysis. The hierarchical porous structure of the carbon substrate was beneficial to enhancing the Li⁺/Na⁺ storage of the active materials, and the carbon wrappings derived from polyacrylonitrile (PAN) nanofibers and the MOF skeleton could jointly accommodate the violent volume variation during cycling, enabling Sn@C@CNF to have excellent cycle stability. The Sn@C@CNF anode exhibited a stable discharge specific capacity of 610.8 mAh g^-1 under 200 mA g^-1 for 180 cycles in lithium ion batteries (LIBs) and 360.5 mAh g^-1 under 100 mA g^-1 after 100 cycles in sodium ion batteries (SIBs). As a flexible electrode, Sn@C@CNF demonstrated a stable electromechanical response to repeated 'bending-releasing' cycles and excellent electrochemical performance when assembled in a soft-pack half-LIB. This strategy provided promising candidates of active materials and fabrication methods for advanced flexible batteries.

Metal-organic framework derived amorphous VOx coated Fe3O4/C hierarchical nanospindle as anode material for superior lithium-ion batteries

Lithium-ion batteries (LIBs) are widely regarded as a promising electrochemical energy storage device, due to their high energy density and good cycling stability. To date, the development of anode materials for LIBs is still confronted with many serious problems, and much effort is required for constructing more ideal anode materials. Herein, starting with metal-organic frameworks (MOFs), an amorphous VO_x coated Fe₃O₄/C hierarchical nanospindle has been successfully synthesized. The obtained Fe₃O₄/C@VO_x nanospindle has a uniform particle size of ∼100 nm in diameter and ∼400 nm in length and consists of ultrafine Fe₃O₄ nanoparticles (∼5 nm) embedded in a porous carbon matrix as the core and an amorphous VO_x layer as the shell. Notably, as the anode material for LIBs, Fe₃O₄/C@VO_x delivers a high coulombic efficiency (74.2%) and a large capacity of 845 mA h g^-1 after 500 cycles at 1000 mA g^-1. A prominent discharge reversible capacity of 340 mA h g^-1 is also still retained at 5000 mA g^-1. More importantly, the presented facile MOF-derived route could be easily extended to other functional materials for widespread applications.

Monodisperse CoSn and NiSn Nanoparticles Supported on Commercial Carbon as Anode for Lithium- and Potassium-Ion Batteries

Monodisperse CoSn and NiSn nanoparticles were prepared in solution and supported on commercial carbon black. The obtained nanocomposites were applied as anodes for Li- and K-ion batteries. CoSn@C delivered stable average capacities of 850, 650, and 500 mAh g^-1 at 0.2, 1.0, and 2.0 A g^-1, respectively, well above those of commercial graphite anodes. The capacity of NiSn@C retained up to 575 mAh g^-1 at a current of 1.0 A g^-1 over 200 continuous cycles. Up to 74.5 and 69.7% pseudocapacitance contributions for Li-ion batteries were measured for CoSn@C and NiSn@C, respectively, at 1.0 mV s^-1. CoSn@C was further tested in full-cell lithium-ion batteries with a LiFePO₄ cathode to yield a stable capacity of 350 mAh g^-1 at a rate of 0.2 A g^-1. As electrode in K-ion batteries, CoSn@C composites presented a stable capacity of around 200 mAh g^-1 at 0.2 A g^-1 over 400 continuous cycles, and NiSn@C delivered a lower capacity of around 100 mAh g^-1 over 300 cycles.

Hierarchical Sulfur-Doped Graphene Foam Embedded with Sn Nanoparticles for Superior Lithium Storage in LiFSI-Based Electrolyte

Lithium-ion batteries based on tin (Sn) anode have the advantage of high energy density at a reasonable cost. However, their commercialization suffers from rapid capacity fading caused by active material aggregation, huge volumetric change, and continuous formation/deformation of solid-electrolyte interphase (SEI). Herein, we report an anode made of nanosized metallic Sn particles embedded in a hierarchically porous sulfur-doped graphene foam (Sn@3DSG). In this design, the sulfur-doped graphene foam provides abundant active defect sites to facilitate the rapid lithium-ion diffusion from outside to inside the Sn nanoparticles. Meanwhile, the hierarchical pores resulting from the self-assembly of graphene and evaporation of nanosized metallic Zn provide sufficient space to hold the volumetric changes of Sn. Owing to these merits, the as-prepared Sn electrode exhibits an excellent lithiated capacity (1272 mA h g^-1 at 200 mA g^-1) and high-rate performance (345 mA h g^-1 at 2000 mA g^-1) in the LiFSI-based electrolyte. It is also discovered that a LiF-Li₃N-rich SEI layer is formed on the surface of the Sn electrode in a LiFSI-based electrolyte, which is beneficial for enhancing the electrode's cycling stability. Our work shows great promise of composite Sn anodes for future high-energy-density lithium-ion batteries.

Carbon framework microbelt supporting SnOx as a high performance electrode for lithium ion batteries

Facile preparation of rational SnO_x-based electrode materials with excellent electrochemical performance is highly desired for lithium ion batteries (LIBs). In this work, carbon framework microbelt supporting SnO_x nanoparticles (CFM-SnO_x) were prepared via a facile electrospinning technology and annealing treatment process. The as-synthesized CFM-SnO_x electrode exhibits high reversible capacity of 768 mAh g^-1 at 0.2 A g^-1 after 200 cycles, high rate capacity of 535 mAh g^-1 at high current density of 3.2 A g^-1. The facile synthesis and superior performance indicate that the as-synthesized CFM-SnO_x is a competitive anode material for LIBs.

Co3Sn2/SnO2 nanocomposite loaded on Cu foam as high-performance three-dimensional anode for lithium-ion batteries

It is a challenge to commercialize tin dioxide-based anodes for lithium-ion batteries due to their low rate capability and poor cycling performance of the electrodes.

Ultrafine Mo-doped SnO2 nanostructure and derivative Mo-doped Sn/C nanofibers for high-performance lithium-ion batteries

Tin-based materials have been intensively studied as attractive candidates for high-capacity and long-cycle-life anodes in Li-ion batteries (LIBs) owing to their low cost and high energy density. However, they all suffer from severe structural decay during the lithium ion insertion/extraction process, which results in deterioration in the overall performance of the batteries. To mitigate this problem, we have synthesized a Mo-doped SnO2 nanostructure via a facile hydrothermal method, which then fragmented into ultrafine particles after dozens of cycles. The fracture-resistant size and ample contact with Super-P and Li2O greatly improved the electrochemical kinetics and cyclability to deliver a reversible capacity of 670 mA h g-1 after 700 cycles, which demonstrated the potential suitability of Mo-doped SnO2 nanoparticles as a long-cycle-life anode material. Then, the compounds were uniformly dispersed in carbon nanofibers and reduced in situ to prepare a free-standing anode via electrospinning and carbonization. When used directly as an anode in LIBs (without a polymeric binder or conductive agent, as well as a current collector), the nanofiber membrane anode delivered comparable cycling performance and capacity to that of a slurry-coated electrode.

Metallic Sn-Based Anode Materials: Application in High-Performance Lithium-Ion and Sodium-Ion Batteries

With the fast-growing demand for green and safe energy sources, rechargeable ion batteries have gradually occupied the major current market of energy storage devices due to their advantages of high capacities, long cycling life, superior rate ability, and so on. Metallic Sn-based anodes are perceived as one of the most promising alternatives to the conventional graphite anode and have attracted great attention due to the high theoretical capacities of Sn in both lithium-ion batteries (LIBs) (994 mA h g-1) and sodium-ion batteries (847 mA h g-1). Though Sony has used Sn-Co-C nanocomposites as its commercial LIB anodes, to develop even better batteries using metallic Sn-based anodes there are still two main obstacles that must be overcome: poor cycling stability and low coulombic efficiency. In this review, the latest and most outstanding developments in metallic Sn-based anodes for LIBs and SIBs are summarized. And it covers the modification strategies including size control, alloying, and structure design to effectually improve the electrochemical properties. The superiorities and limitations are analyzed and discussed, aiming to provide an in-depth understanding of the theoretical works and practical developments of metallic Sn-based anode materials.

One-step synthesis of SnCo nanoconfined in hierarchical carbon nanostructures for lithium ion battery anode

A new strategy for the one-step synthesis of a 0D SnCo nanoparticles-1D carbon nanotubes-3D hollow carbon submicrocube cluster (denoted as SnCo@CNT-3DC) hierarchical nanostructured material was developed via a simple chemical vapor deposition (CVD) process with the assistance of a water-soluble salt (NaCl). The adopted NaCl not only acted as a cubic template for inducing the formation of the 3D hollow carbon submicrocube cluster but also provides a substrate for the SnCo catalysts impregnation and CNT growth, ultimately leading to the successful construction of the unique 0D-1D-3D structured SnCo@CNT-3DC during the CVD of C₂H₂. When utilized as a lithium-ion battery anode, the SnCo@CNT-3DC composite electrode demonstrated an excellent rate performance and cycling stability for Li-ion storage. Specifically, an impressive reversible capacity of 826 mA h g^-1 after 100 cycles at 0.1 A g^-1 and a high rate capacity of 278 mA h g^-1 even after 1000 cycles at 5 A g^-1 were achieved. This remarkable electrochemical performance could be ascribed to the unique hierarchical nanostructure of SnCo@CNT-3DC, which guarantees a deep permeation of electrolytes and a shortened lithium salt diffusion pathway in the solid phase as well as numerous hyperchannels for electron transfer.

Gd–Sn alloys and Gd–Sn–graphene composites as anode materials for lithium-ion batteries

Gd–Sn alloys and Gd–Sn–graphene composites are prepared by a simple route. GdSn₆/G composites have higher reversible discharge capacities than Gd–Sn powders.

Multi-yolk-shell SnO2/Co3Sn2@C Nanocubes with High Initial Coulombic Efficiency and Oxygen Reutilization for Lithium Storage

The challenging problems of SnO₂ anode material for lithium ion batteries are the poor electronic conductivity and the low oxygen reutilization due to the irreversibility of Li₂O generated in the initial discharge leading to a theoretical initial Coulombic efficiency (ICE) of only 52.4%. Different from these strategies, this work proposes a novel strategy to level up the oxygen reutilization in SnO₂ by introducing Co₃Sn₂ nanoalloys which can release Co atoms to reversibly react with Li₂O instead. According to this protocol, multi-yolk-shell SnO₂/Co₃Sn₂@C nanocubes are designed and successfully prepared using hollow CoSn(OH)₆ nanocubes as precursors followed a hydrothermal carbon coating and calcination treatment. The unique multi-yolk-shell nanostructure offers adequate breathing space for the volumetric deformation during long-term cycling. Moreover, the removal of Li₂O allows a high electronic conductivity and resultant rate performance. As a result, the efficient reutilization of oxygen enables a high ICE of 71.7% and a reversible capacity of 1003 mA h g^-1 after 200 cycles at 100 mA g^-1. Cyclic voltammetry, cycling performance at different voltage windows, and X-ray photoelectron spectroscopy confirm the proposed mechanism. This strategy employing oxygen-poor metals or alloys provides a novel approach to enhance the oxygen reutilization in SnO₂ for higher reversibility.

Galvanic Exchange in Colloidal Metal/Metal-Oxide Core/Shell Nanocrystals

While galvanic exchange is commonly applied to metallic nanoparticles, recently its applicability was expanded to metal-oxides. Here the galvanic exchange is studied in metal/metal-oxide core/shell nanocrystals. In particular Sn/SnO₂ is treated by Ag⁺, Pt²⁺, Pt⁴⁺, and Pd²⁺. The conversion dynamics is monitored by in situ synchrotron X-ray diffraction. The Ag⁺ treatment converts the Sn cores to the intermetallic Ag _x Sn (x ∼ 4) phase, by changing the core's crystal structure. For the analogous treatment by Pt²⁺, Pt⁴⁺, and Pd²⁺, such a galvanic exchange is not observed. This different behavior is caused by the semipermeability of the naturally formed SnO₂ shell, which allows diffusion of Ag⁺ but protects the nanocrystal cores from oxidation by Pt and Pd ions.

3D Scaffolded Nickel-Tin Li-Ion Anodes with Enhanced Cyclability

A 3D mechanically stable scaffold is shown to accommodate the volume change of a high-specific-capacity nickel-tin nanocomposite during operation as a Li-ion battery anode. The nickel-tin anode is supported by an electrochemically inactive conductive scaffold with an engineered free volume and controlled characteristic dimensions, which engender the electrode with significantly improved cyclability.

Simple preparation of Cu6Sn5/Sn composites as anode materials for lithium-ion batteries

Cu₆Sn₅/Sn composites are directly fabricated by a high energy mechanical milling technique and subsequent heat treatment.

Three-dimensional porous carbon nanosheet networks anchored with Cu6Sn5@carbon as a high-performance anode material for lithium ion batteries

A three-dimensional porous carbon nanosheet networks anchored with Cu₆Sn₅@carbon nanoparticles as a high-performance anode of lithium ion batteries are synthesized.

Nano-Sn doped carbon-coated rutile TiO2 spheres as a high capacity anode for Li-ion battery

Nano-Sn doped carbon-coated rutile TiO₂ spheres (C-NS/TiO₂-1 and C-NS/TiO₂-2) as an improved TiO₂-based anode for Li-ion batteries were in situ fabricated.