A Multi‐Wall Sn/SnO2@Carbon Hollow Nanofiber Anode Material for High‐Rate and Long‐Life Lithium‐Ion Batteries

Multi‐wall Sn/SnO₂@carbon hollow nanofibers evolved from SnO₂ nanofibers are designed and programable synthesized by electrospinning, polypyrrole coating, and annealing reduction. The synthesized hollow nanofibers have a special wire‐in‐double‐wall‐tube structure with larger specific surface area and abundant inner spaces, which can provide effective contacting area of electrolyte with electrode materials and more active sites for redox reaction. It shows excellent cycling stability by virtue of effectively alleviating pulverization of tin‐based electrode materials caused by volume expansion. Even after 2000 cycles, the wire‐in‐double‐wall‐tube Sn/SnO₂@carbon nanofibers exhibit a high specific capacity of 986.3 mAh g^?1 (1 A g^?1) and still maintains 508.2 mAh g^?1 at high current density of 5 A g^?1. This outstanding electrochemical performance suggests the multi‐wall Sn/SnO₂@ carbon hollow nanofibers are great promising for high performance energy storage systems.     

Bullet‐like Cu9S5 Hollow Particles Coated with Nitrogen‐Doped Carbon for Sodium‐Ion Batteries

Metal sulfides with excellent redox reversibility and high capacity are very promising electrode materials for sodium‐ion batteries. However, their practical application is still hindered by the poor rate capability and limited cycle life. Herein, a template‐based strategy is developed to synthesize nitrogen‐doped carbon‐coated Cu₉S₅ bullet‐like hollow particles starting from bullet‐like ZnO particles. With the structural and compositional advantages, these unique nitrogen‐doped carbon‐coated Cu₉S₅ bullet‐like hollow particles manifest excellent sodium storage properties with superior rate capability and ultra‐stable cycling performance.     

Polymer‐Templated Formation of Polydopamine‐Coated SnO2 Nanocrystals: Anodes for Cyclable Lithium‐Ion Batteries

Well‐controlled nanostructures and a high fraction of Sn/Li₂O interface are critical to enhance the coulombic efficiency and cyclic performance of SnO₂‐based electrodes for lithium‐ion batteries (LIBs). Polydopamine (PDA)‐coated SnO₂ nanocrystals, composed of hundreds of PDA‐coated “corn‐like” SnO₂ nanoparticles (diameter ca. 5 nm) decorated along a “cob”, addressed the irreversibility issue of SnO₂‐based electrodes. The PDA‐coated SnO₂ were crafted by capitalizing on rationally designed bottlebrush‐like hydroxypropyl cellulose‐graft‐poly (acrylic acid) (HPC‐g ‐PAA) as a template and was coated with PDA to construct a passivating solid‐electrolyte interphase (SEI) layer. In combination, the corn‐like nanostructure and the protective PDA coating contributed to a PDA‐coated SnO₂ electrode with excellent rate capability, superior long‐term stability over 300 cycles, and high Sn→SnO₂ reversibility.     

A Multi-Wall Sn/SnO2@Carbon Hollow Nanofiber Anode Material for High-Rate and Long-Life Lithium-Ion Batteries

Multi-wall Sn/SnO₂@carbon hollow nanofibers evolved from SnO₂ nanofibers are designed and programable synthesized by electrospinning, polypyrrole coating, and annealing reduction. The synthesized hollow nanofibers have a special wire-in-double-wall-tube structure with larger specific surface area and abundant inner spaces, which can provide effective contacting area of electrolyte with electrode materials and more active sites for redox reaction. It shows excellent cycling stability by virtue of effectively alleviating pulverization of tin-based electrode materials caused by volume expansion. Even after 2000 cycles, the wire-in-double-wall-tube Sn/SnO₂@carbon nanofibers exhibit a high specific capacity of 986.3 mAh g⁻¹ (1 A g⁻¹) and still maintains 508.2 mAh g⁻¹ at high current density of 5 A g⁻¹. This outstanding electrochemical performance suggests the multi-wall Sn/SnO₂@ carbon hollow nanofibers are great promising for high performance energy storage systems.     

Hollow Multi‐Shelled Structure with Metal–Organic‐Framework‐Derived Coatings for Enhanced Lithium Storage

Herein, we present heterogeneous hollow multi‐shelled structures (HoMSs) prepared by exploiting the properties of the metal–organic framework (MOFs) casing. Through accurately controlling the transformation of MOF layer into different heterogeneous casings, we can precisely design HoMSs of SnO₂@Fe₂O₃(MOF) and SnO₂@FeO_x‐C(MOF), which not only retain properties of the original SnO₂‐HoMSs, but also structural information from the MOFs. Tested as anode materials in LIBs, SnO₂@Fe₂O₃ (MOF)‐HoMSs demonstrate superior lithium‐storage capacity and cycling stability to the original SnO₂‐HoMSs, which can be attributed to the topological features from the MOF casing. Making a sharp contrast to the electrodes of SnO₂@Fe₂O₃ (particle)‐HoMSs fabricated by hydrothermal method, the capacity retention after 100 cycles for the SnO₂@Fe₂O₃ (MOF)‐HoMSs is about eight times higher than that of the SnO₂@Fe₂O₃ (particle)‐HoMS.     

Self‐Templated Formation of Uniform NiCo2O4 Hollow Spheres with Complex Interior Structures for Lithium‐Ion Batteries and Supercapacitors

Despite the significant advancement in preparing metal oxide hollow structures, most approaches rely on template‐based multistep procedures for tailoring the interior structure. In this work, we develop a new generally applicable strategy toward the synthesis of mixed‐metal‐oxide complex hollow spheres. Starting with metal glycerate solid spheres, we show that subsequent thermal annealing in air leads to the formation of complex hollow spheres of the resulting metal oxide. We demonstrate the concept by synthesizing highly uniform NiCo₂O₄ hollow spheres with a complex interior structure. With the small primary building nanoparticles, high structural integrity, complex interior architectures, and enlarged surface area, these unique NiCo₂O₄ hollow spheres exhibit superior electrochemical performances as advanced electrode materials for both lithium‐ion batteries and supercapacitors. This approach can be an efficient self‐templated strategy for the preparation of mixed‐metal‐oxide hollow spheres with complex interior structures and functionalities.     

One‐Step Synthesis of SnO2 and TiO2 Hollow Nanostructures with Various Shapes and Their Enhanced Lithium Storage Properties

A versatile one‐step method for the general synthesis of metal oxide hollow nanostructures is demonstrated. This method involves the controlled deposition of metal oxides on shaped α‐Fe₂O₃ crystals which are simultaneously dissolved. A variety of uniform SnO₂ hollow nanostructures, such as nanococoons, nanoboxes, hollow nanorings, and nanospheres, can be readily generated. The method is also applicable to the synthesis of shaped TiO₂ hollow nanostructures. As a demonstration of the potential applications of these hollow nanostructures, the lithium storage capability of SnO₂ hollow structures is investigated. The results show that such derived SnO₂ hollow structures exhibit stable capacity retention of 600–700 mAh g^?1 for 50 cycles at a 0.2 C rate and good rate capability at 0.5–1 C, perhaps benefiting from the unique structural characteristics.     

Controllable Synthesis of Mesoporous Peapod‐like Co3O4@Carbon Nanotube Arrays for High‐Performance Lithium‐Ion Batteries

Transition metal oxides are regarded as promising anode materials for lithium‐ion batteries because of their high theoretical capacities compared with commercial graphite. Unfortunately, the implementation of such novel anodes is hampered by their large volume changes during the Li⁺ insertion and extraction process and their low electric conductivities. Herein, we report a specifically designed anode architecture to overcome such problems, that is, mesoporous peapod‐like Co₃O₄@carbon nanotube arrays, which are constructed through a controllable nanocasting process. Co₃O₄ nanoparticles are confined exclusively in the intratubular pores of the nanotube arrays. The pores between the nanotubes are open, and thus render the Co₃O₄ nanoparticles accessible for effective electrolyte diffusion. Moreover, the carbon nanotubes act as a conductive network. As a result, the peapod‐like Co₃O₄@carbon nanotube electrode shows a high specific capacity, excellent rate capacity, and very good cycling performance.     

In Situ Growth of Hierarchical SnO2 Nanosheet Arrays on 3D Macroporous Substrates as High‐Performance Electrodes

Finding out how to overcome the self‐aggregation of nanostructured electrode materials is a very important issue in lithium‐ion battery technology. Herein, by an in situ construction strategy, hierarchical SnO₂ nanosheet architectures have been fabricated on a three‐dimensional macroporous substrate, and thus the aggregation of the SnO₂ nanosheets was effectively prevented. The as‐prepared hierarchical SnO₂ nanoarchitectures on the nickel foam can be directly used as an integrated anode for lithium‐ion batteries without the addition of other ancillary materials such as carbon black or binder. In view of their apparent advantages, such as high electroactive surface area, ultrathin sheet, robust mechanical strength, shorter ion and electron transport path, and the specific macroporous structure, the hierarchical SnO₂ nanosheets exhibit excellent lithium‐storage performance. Our present growth approach offers a new technique for the design and synthesis of metal oxide hierarchical nanoarrays that are promising for electrochemical energy‐storage electrodes without carbon black and binder.     

Carbon‐Coated Hierarchical SnO2 Hollow Spheres for Lithium Ion Batteries

Hierarchical SnO₂ hollow spheres self‐assembled from nanosheets were prepared with and without carbon coating. The combination of nanosized architecture, hollow structure, and a conductive carbon layer endows the SnO₂‐based anode with improved specific capacity and cycling stability, making it more promising for use in lithium ion batteries.     

High‐Loading Nano‐SnO2 Encapsulated in situ in Three‐Dimensional Rigid Porous Carbon for Superior Lithium‐Ion Batteries

Tin oxide nanoparticles (SnO₂ NPs) have been encapsulated in situ in a three‐dimensional ordered space structure. Within this composite, ordered mesoporous carbon (OMC) acts as a carbon framework showing a desirable ordered mesoporous structure with an average pore size (≈6 nm) and a high surface area (470.3 m² g^?1), and the SnO₂ NPs (≈10 nm) are highly loaded (up to 80 wt %) and homogeneously distributed within the OMC matrix. As an anode material for lithium‐ion batteries, a SnO₂@OMC composite material can deliver an initial charge capacity of 943 mAh g^?1 and retain 68.9 % of the initial capacity after 50 cycles at a current density of 50 mA g^?1, even exhibit a capacity of 503 mA h g^?1 after 100 cycles at 160 mA g^?1. In situ encapsulation of the SnO₂ NPs within an OMC framework contributes to a higher capacity and a better cycling stability and rate capability in comparison with bare OMC and OMC ex situ loaded with SnO₂ particles (SnO₂/OMC). The significantly improved electrochemical performance of the SnO₂@OMC composite can be attributed to the multifunctional OMC matrix, which can facilitate electrolyte infiltration, accelerate charge transfer, and lithium‐ion diffusion, and act as a favorable buffer to release reaction strains for lithiation/delithiation of the SnO₂ NPs.     

A New Concept for Obtaining SnO2 Fiber‐in‐Tube Nanostructures with Superior Electrochemical Properties

Tin oxide (SnO₂) nanotubes with a fiber‐in‐tube structure have been prepared by electrospinning and the mechanism of their formation has been investigated. Tin oxide‐carbon composite nanofibers with a filled structure were formed as an intermediate product, which were then transformed into SnO₂ nanotubes with a fiber‐in‐tube structure during heat treatment at 500 °C. Nanofibers with a diameter of 85 nm were found to be located inside hollow nanotubes with an outer diameter of 260 nm. The prepared SnO₂ nanotubes had well‐developed mesopores. The discharge capacities of the SnO₂ nanotubes at the 2nd and 300th cycles at a current density of 1 A g^?1 were measured as 720 and 640 mA h g^?1, respectively, and the corresponding capacity retention measured from the 2nd cycle was 88 %. The discharge capacities of the SnO₂ nanotubes at incrementally increased current densities of 0.5, 1.5, 3, and 5 A g^?1 were 774, 711, 652, and 591 mA h g^?1, respectively. The SnO₂ nanotubes with a fiber‐in‐tube structure showed superior cycling and rate performances compared to those of SnO₂ nanopowder. The unique structure of the SnO₂ nanotubes with a fiber@void@tube configuration improves their electrochemical properties by reducing the diffusion length of the lithium ions, and also imparts greater stability during electrochemical cycling.     

Boron‐Doped,Carbon‐Coated SnO2/Graphene Nanosheets for Enhanced Lithium Storage

Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron‐doped, carbon‐coated SnO₂/graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO₂/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core–shell architecture and B‐doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium‐ion batteries with a highly stable capacity of 1165 mA h g^?1 at 0.1 A g^?1 after 360 cycles and an excellent rate capability of 600 mA h g^?1 at 3.2 A g^?1, and thus outperforms most of the previously reported SnO₂‐based anode materials.     

Lattice Distortion in Hollow Multi‐Shelled Structures for Efficient Visible‐Light CO2 Reduction with a SnS2/SnO2 Junction

Precise control of the micro‐/nanostructures of nanomaterials, such as hollow multi‐shelled structures (HoMSs), has shown its great advantages in various applications. Now, the crystal structure of building blocks of HoMSs are controlled by introducing the lattice distortion in HoMSs, for the first time. The lattice distortion located at the nanoscale interface of SnS₂/SnO₂ can provide additional active sites, which not only provide the catalytic activity under visible light but also improve the separation of photoexcited electron–hole pairs. Combined with the efficient light utilization, the natural advantage of HoMSs, a record catalytic activity was achieved in solid–gas system for CO₂ reduction, with an excellent stability and 100 % CO selectivity without using any sensitizers or noble metals.     

Template‐Free Synthesis of Hierarchical Vanadium‐Glycolate Hollow Microspheres and Their Conversion to V2O5 with Improved Lithium Storage Capability

Nanosheet‐assembled hierarchical V₂O₅ hollow microspheres are successfully obtained from V‐glycolate precursor hollow microspheres, which in turn are synthesized by a simple template‐free solvothermal method. The structural evolution of the V‐glycolate hollow microspheres has been studied and explained by the inside‐out Ostwald‐ripening mechanism. The surface morphologies of the hollow microspheres can be controlled by varying the mixture solution and the solvothermal reaction time. After calcination in air, hierarchical V₂O₅ hollow microspheres with a high surface area of 70 m² g^?1 can be obtained and the structure is well preserved. When evaluated as cathode materials for lithium‐ion batteries, the as‐prepared hierarchical V₂O₅ hollow spheres deliver a specific discharge capacity of 144 mA h g^?1 at a current density of 100 mA g^?1, which is very close to the theoretical capacity (147 mA h g^?1) for one Li⁺ insertion per V₂O₅. In addition, excellent rate capability and cycling stability are observed, suggesting their promising use in lithium‐ion batteries.     

Hierarchical SnO2/Carbon Nanofibrous Composite Derived from Cellulose Substance as Anode Material for Lithium‐Ion Batteries

A hierarchical fibrous SnO₂/carbon nanocomposite composed of fine SnO₂ nanocrystallites immobilized as a thin layer on a carbon nanofiber surface was synthesized employing natural cellulose substance as both scaffold and carbon source. It was achieved by calcination/carbonization of the as‐deposited SnO₂‐gel/cellulose hybrid in an argon atmosphere. As being employed as an anode material for lithium‐ion batteries, the porous structures, small SnO₂ crystallite sizes, and the carbon buffering matrix possessed by the nanocomposite facilitate the electrode–electrolyte contact, promote the electron transfer and Li⁺ diffusion, and relieve the severe volume change and aggregation of the active particles during the charge/discharge cycles. Hence, the nanocomposite showed high reversible capacity, significant cycling stability, and rate capability that are superior to the nanotubular SnO₂ and SnO₂ sol–gel powder counter materials. For such a composite with 27.8 wt % SnO₂ content and 346.4 m² g^?1 specific surface area, a capacity of 623 mAh g^?1 was delivered after 120 cycles at 0.2 C. Further coating of the SnO₂/carbon nanofibers with an additional carbon layer resulted in an improved cycling stability and rate performance.     

Formation of Triple‐Shelled Molybdenum–Polydopamine Hollow Spheres and Their Conversion into MoO2/Carbon Composite Hollow Spheres for Lithium‐Ion Batteries

Unique triple‐shelled Mo‐polydopamine (Mo‐PDA) hollow spheres are synthesized through a facile solvothermal process. A sequential self‐templating mechanism for the multi‐shell formation is proposed, and the number of shells can be adjusted by tuning the size of the Mo‐glycerate templates. These triple‐shelled Mo‐PDA hollow spheres can be converted to triple‐shelled MoO₂/carbon composite hollow spheres by thermal treatment. Owing to the unique multi‐shells and hollow interior, the as‐prepared MoO₂/carbon composite hollow spheres exhibit appealing performance as an anode material for lithium‐ion batteries, delivering a high capacity of ca. 580 mAh g^?1 at 0.5 A g^?1 with good rate capability and long cycle life.     

Double‐Shelled C@MoS2 Structures Preloaded with Sulfur: An Additive Reservoir for Stable Lithium Metal Anodes

The growth of Li dendrites hinders the practical application of lithium metal anodes (LMAs). In this work, a hollow nanostructure, based on hierarchical MoS₂ coated hollow carbon particles preloaded with sulfur (C@MoS₂/S), was designed to modify the LMA. The C@MoS₂ hollow nanostructures serve as a good scaffold for repeated Li plating/stripping. More importantly, the encapsulated sulfur could gradually release lithium polysulfides during the Li plating/stripping, acting as an effective additive to promote the formation of a mosaic solid electrolyte interphase layer embedded with crystalline hybrid lithium‐based components. These two factors together effectively suppress the growth of Li dendrites. The as‐modified LMA shows a high Coulombic efficiency of 98 % over 500 cycles at the current density of 1 mA cm^?2. When matched with a LiFePO₄ cathode, the assembled full cell displays a highly improved cycle life of 300 cycles, implying the feasibility of the proposed LMA.     

Synthesis of Highly Uniform Molybdenum–Glycerate Spheres and Their Conversion into Hierarchical MoS2 Hollow Nanospheres for Lithium‐Ion Batteries

Highly uniform Mo–glycerate solid spheres are synthesized for the first time through a solvothermal process. The size of these Mo–glycerate spheres can be easily controlled in the range of 400–1000 nm by varying the water content in the mixed solvent. As a precursor, these Mo–glycerate solid spheres can be converted into hierarchical MoS₂ hollow nanospheres through a subsequent sulfidation reaction. Owing to the unique ultrathin subunits and hollow interior, the as‐prepared MoS₂ hollow nanospheres exhibit appealing performance as the anode material for lithium‐ion batteries. Impressively, these hierarchical structures deliver a high capacity of about 1100 mAh g^?1 at 0.5 A g^?1 with good rate retention and long cycle life.     

纳米硫化铜颗粒自组装为球、空心球和线形结构

用水和乙二醇混合物为溶剂,应用溶剂热合成方法制备了由纳米颗粒自组装的球、空心球和线形结构的铜的硫化物,如 Cu7S4, Cu1.8S, Cu1.81S 和 Cu2S。 考查了溶剂组成（水含量的变化）、反应时间、实验温度的变化对所制备样品的形貌和物相结构的影响。研究了其形成机理。结果表明,随着反应时间的变化,首先形成纳米颗粒的铜的硫化物。通过自组装形成线形结构。最后转化为球形或空心球形结构。