Search

Subnanometer pores/channels (SNPCs) play crucial roles in regulating electrochemical redox reactions for rechargeable batteries. The delicately designed and tailored porous structure of SNPCs not only provides ample space for ion storage but also facilitates efficient ion diffusion within the electrodes in batteries, which can greatly improve the electrochemical performance. However, due to current technological limitations, it is challenging to synthesize and control the quality, storage, and transport of nanopores at the subnanometer scale, as well as to understand the relationship between SNPCs and performances. In this review, we systematically classify and summarize materials with SNPCs from a structural perspective, dividing them into one-dimensional (1D) SNPCs, two-dimensional (2D) SNPCs, and three-dimensional (3D) SNPCs. We also unveil the unique physicochemical properties of SNPCs and analyse electrochemical couplings in SNPCs for rechargeable batteries, including cathodes, anodes, electrolytes, and functional materials. Finally, we discuss the challenges that SNPCs may face in electrochemical reactions in batteries and propose future research directions. [ABSTRACT FROM AUTHOR]

Sodium metal is one of the ideal anodes for high-performance rechargeable batteries because of its high specific capacity (~ 1166 mAh·g−1), low reduction potential (−2.71 V compared to standard hydrogen electrodes), and low cost. However, the unstable solid electrolyte interphase, uncontrolled dendrite growth, and inevitable volume expansion hinder the practical application of sodium metal anodes. At present, many strategies have been developed to achieve stable sodium metal anodes. Here, we systematically summarize the latest strategies adopted in interface engineering, current collector design, and the emerging methods to improve the reaction kinetics of sodium deposition processes. First, the strategies of constructing protective layers are reviewed, including inorganic, organic, and mixed protective layers through electrolyte additives or pretreatments. Then, the classification of metal-based, carbon-based, and composite porous frames is discussed, including their function in reducing local deposition current density and the effect of introducing sodiophilic sites. Third, the recent progress of alloys, nanoparticles, and single atoms in improving Na deposition kinetics is systematically reviewed. Finally, the future research direction and the prospect of high-performance sodium metal batteries are proposed. [ABSTRACT FROM AUTHOR]

Alloy‐based anodes have shown great potential to be applied in sodium‐ion batteries (SIBs) due to their high theoretical capacities, suitable working potential, and abundant earth reserves. However, their practical applications are severely impeded by large volume expansion, unstable solid‐electrolyte interfaces (SEI), and sluggish reaction kinetics during cycling. Herein, a surface engineering of tin nanorods via N‐doped carbon layers (Sn@NC) and an interface engineering strategy to improve the electrochemical performance in SIBs are reported. In particular, the authors demonstrate that uniform surface modification can effectively facilitate electron and sodium transport kinetics, confine alloy pulverization, and simultaneously synergize interactions with the ether‐based electrolyte to form a robust organic‐inorganic SEI. Moreover, it is discovered that the diethylene glycol dimethyl ether electrolyte with strong stability and an optimized Na+ solvation structure can co‐embed the carbon layer to achieve fast reaction kinetics. Consequently, Sn@NC anodes deliver extra‐long cycling stability of more than 10 000 cycles. The full cell of Na3V2(PO4)3║Sn@NC exhibits high energy density (215 Wh kg−1), excellent high‐rate capability (reaches 80% capacity in 2 min), and long cycle life over a wide temperature range of −20 to 50 °C. [ABSTRACT FROM AUTHOR]

Lithium‐metal (Li‐metal) batteries are one of the most potential energy storage devices available these days. However, uncontrollable lithium dendritic growth and parasitic reactions lead to poor cycling efficiency and severe safety concerns, which restricts the use of Li‐metal batteries in practical applications. This article reviews the current development status of Li‐metal anodes, including investigations of reaction mechanisms and performance improvement strategies. In addition, future opportunities for developing safe and high‐performance Li‐metal batteries are also outlined. [ABSTRACT FROM AUTHOR]

Constructing an advanced artificial solid electrolyte interphase (SEI) on lithium metal anodes is a promising strategy to protect Li anodes and enable them to maintain long‐term cycling stability and safety. Herein, the development of a dual‐protective interface as an artificial SEI with high ionic conductivity and appropriate mechanical strength to protect Li anodes from parasitic reactions and dendrite formation is reported. The dual‐protective interface consists of a Prussian blue (PB) inner layer and a reduced graphene oxide (rGO) outer layer. The compact and uniform PB layer with abundant Li‐ion diffusion channels facilitates fast and uniform Li‐ion flux to or from the surface of the Li metal anode, guiding uniform Li deposition without dendrite formation. In addition, the flexible rGO layer on the top of the PB layer enhances the structural integrity of the PB film against severe volume change during repeated Li plating and stripping. As a result, the Li metal anodes with the dual‐protective interfaces show significantly improved cycling stability with high Coulombic efficiency and dendrite‐free morphology. This work provides a new strategy to enhance the stability and safety of Li metal anodes for lithium metal batteries. [ABSTRACT FROM AUTHOR]

Silicon has been regarded as an attractive high‐capacity anode material for next‐generation lithium‐ion batteries (LIBs). However, Si anodes suffer from huge volume variation during cycling, which poses a critical challenge for stable battery operation. Compared with Si, Si suboxide (SiOx) is one of the most promising candidates for high‐energy‐density LIBs because of its alleviated swelling and highly stable cycling performance. Whereas, the poor electronic conductivity and low (initial) Coulombic efficiency of SiOx anodes severely hinder practical applications for LIBs. Herein, for the first time, these issues are successfully solved through rationally designing hollow‐structured SiOx@carbon nanotubes (CNTs)/C architectures with graphitic carbon coatings and in situ growth of CNTs. When applied as anodes in LIBs, the SiOx@CNTs/C anodes exhibit high reversible capacity, high initial Coulombic efficiency (88%), outstanding cycling performance, and extraordinary mechanical strength during the calendaring process (200 MPa). This work paves the way for developing SiOx‐based anode materials for high‐energy‐density LIBs. [ABSTRACT FROM AUTHOR]

The last 10 years established the beginning of a post‐lithium era in the field of energy storage, with the renaissance of Na‐ion batteries (NIBs) as alternative for Li‐based systems. The development of this technology has required intense work in materials research in order to produce and optimize anodes, cathodes, and electrolytes for NIBs. The strong and weak points of the main families of compounds for each battery component are analyzed in this progress report. Taking into account the achievements made in materials for NIBs, the industrial scene is analyzed through the existing prototypes and commercial cells and also from an economical viewpoint. In this scenario, where Na‐ion technology seems to be ready for a coming second generation, the use of Na can be extended to almost the whole spectrum of electrochemical energy storage systems: the new room temperature Na–S systems, high‐energy Na–air technology, or high‐power Na‐based hybrid supercapacitors. Thus, the degree of development of NIBs, together with the promising performance of newer Na‐based energy storage systems, makes Na the key to the coming commercial post‐lithium systems. [ABSTRACT FROM AUTHOR]

The practical applications of lithium metal anodes in high-energy-density lithium metal batteries have been hindered by their formation and growth of lithium dendrites. Herein, we discover that certain protein could efficiently prevent and eliminate the growth of wispy lithium dendrites, leading to long cycle life and high Coulombic efficiency of lithium metal anodes. We contend that the protein molecules function as a "self-defense" agent, mitigating the formation of lithium embryos, thus mimicking natural, pathological immunization mechanisms. When added into the electrolyte, protein molecules are automatically adsorbed on the surface of lithium metal anodes, particularly on the tips of lithium buds, through spatial conformation and secondary structure transformation from α-helix to β-sheets. This effectively changes the electric field distribution around the tips of lithium buds and results in homogeneous plating and stripping of lithium metal anodes. Furthermore, we develop a slow sustained-release strategy to overcome the limited dispersibility of protein in the ether-based electrolyte and achieve a remarkably enhanced cycling performance of more than 2000 cycles for lithium metal batteries. The practical application of lithium metal anodes in high-energy-density lithium metal batteries is hindered by the formation and growth of lithium dendrites. Here, authors report fibroin protein as an electrolyte additive to prevent and eliminate the growth of wispy lithium dendrites. [ABSTRACT FROM AUTHOR]

It is essential to develop a facile and effective method to enhance the electrochemical performance of lithium metal anodes for building high‐energy‐density Li‐metal based batteries. Herein, we explored the temperature‐dependent Li nucleation and growth behavior and constructed a dendrite‐free Li metal anode by elevating temperature from room temperature (20 °C) to 60 °C. A series of ex situ and in situ microscopy investigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density, and compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li‐ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite‐free Li growth behavior. As anodes in both half cells and full cells, the compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 °C. [ABSTRACT FROM AUTHOR]

Abstract: Lithium‐ion batteries have been used to operate various electric devices over the last decade. Electronic devices have been developed rapidly to achieve a high level of performance and enter into new markets. However, lithium‐ion batteries face limitations as a result of the low theoretical energy density of existing materials. Thus, many researchers have sought to investigate different ways to enhance the performance of batteries when used for practical applications. This review revisits the literature related to the development of high performance lithium‐ion batteries, which have been shown to have achieved outstanding results in a full cell test. In particular, the full cell test is critically important when seeking to develop materials that are appropriate for use in practical applications, and it also helps meet the increasing demands of new lithium‐ion batteries that are a result of emerging technology. This review article aims to provide information about the development of lithium‐ion batteries and the latest developments in new materials and nanotechnology. Furthermore, it will outline the challenges faced by the research community in developing advanced batteries and the outlook for the next generation of lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: The development of high energy‐density and low‐cost energy storage devices requires new chemistry beyond the horizon of current state‐of‐the‐art lithium‐ion batteries. Recently, sodium/oxygen (Na/O2) batteries have attracted great attention as one possible battery type among the new generation of rechargeable batteries. They convince with superior energy density, a relatively simple cell reaction, and abundance of sodium. Research on Na/O2 batteries has progressed quickly in recent years. However, a fundamental understanding underpinning the complex chemical/electrochemical side reactions is still insufficient, and many challenges remain unsolved for real practical applications. Herein, recent achievements and remaining issues for the development of rechargeable Na/O2 batteries are summarized. The discussion focuses on cell reaction mechanisms as well as cathode materials, sodium anodes, and electrolytes as key components of this type of battery. Furthermore, perspectives for future research and technological advances of Na/O2 batteries are outlined. [ABSTRACT FROM AUTHOR]

Abstract: Tin disulfide, as a promising high‐capacity anode material for sodium‐ion batteries, exhibits high theoretical capacity but poor practical electrochemical properties due to its low electrical conductivity. Constructing heterostructures has been considered to be an effective approach to enhance charge transfer and ion‐diffusion kinetics. In this work, composites of SnS2/Sb2S3 heterostructures with reduced graphene oxide nanosheets were synthesized by a facile one‐pot hydrothermal method. When applied as anode material in sodium‐ion batteries, the composite showed a high reversible capacity of 642 mA h g−1 at a current density of 0.2 A g−1 and good cyclic stability without capacity loss in 100 cycles. In particular, SnS2/Sb2S3 heterostructures exhibited outstanding rate performance with capacities of 593 and 567 mA h g−1 at high current densities of 2 and 4 A g−1, respectively, which could be ascribed to the dramatically improved Na+ diffusion kinetics and electrical conductivity. [ABSTRACT FROM AUTHOR]

Nanostructured transitional metal oxides have received more and more attention as the electrode materials for lithium-ion batteries to achieve high specific capacity and good safety performance. In this paper, a graphene nanosheet-supported $$\hbox {Mn}_{3}\hbox {O}_{4}$$ nanoparticles ( $$\hbox {Mn}_{3}\hbox {O}_{4}$$ -GNS) composite, as well as $$\hbox {Mn}_{3}\hbox {O}_{4}$$ nanosheet, were synthesized via a facile hydrothermal method. The $$\hbox {Mn}_{3}\hbox {O}_{4}$$ -GNS composite exhibits good electrochemical performances with high reversible specific capacity (an initial charge capacity of 969 mAh $$\hbox {g}^{-1}$$ at 93.6 mA $$\hbox {g}^{-1}$$ ), good cycling stability (a retained capacity of 646 mAh $$\hbox {g}^{-1}$$ after 60 cycles) and rate capability when used as the anode material for LIBs. The enhanced electrochemical performance could be attributed to the nanoscaled particles of $$\hbox {Mn}_{3}\hbox {O}_{4}$$ , the buffer and confine effects of graphene nanosheets (GNSs) and the distinctive synergistic effect between two components of GNS and metal oxides. [ABSTRACT FROM AUTHOR]

Antimony/porous biomass carbon nanocomposites have been prepared by a chemical reduction method and applied as anodes for sodium-ion batteries. The porous biomass carbon derived from a black fungus had a large Brunauer-Emmett-Teller (BET) surface area of 2233 m2 g−1 in which antimony nanoparticles were uniformly distributed in the porous carbon. The as-prepared antimony/porous biomass carbon nanocomposites exhibited a high reversible sodium storage capacity of 567 mA h g−1 at a current density of 100 mA g−1, extended cycling stability, and good rate capability. [ABSTRACT FROM AUTHOR]

Multiwalled carbon nanotube (MWCNT)-ZnMn2O4 nanoparticles were fabricated by a hydrothermal method without further thermal treatment. The morphology and microstructure were investigated by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and the Brunauer-Emmett-Teller method. Owing to the synergistic effect and strongly coupled interaction between the MWCNTs and ZnMn2O4 nanoparticles, the MWCNT-ZnMn2O4 composite material exhibited a higher specific capacity of 809 mA h g−1, good rate capability and stable cycling performance compared to both pristine ZnMn2O4 nanoparticles and MWCNTs, indicating it to be a promising anode material for lithium ion battery applications. [ABSTRACT FROM AUTHOR]

We report the synthesis of hierarchical vanadium pentoxide (V2O5) spheres as anode materials for sodium-ion batteries (Na-ion batteries). Through field emission scanning electron microscopy, X-ray diffraction, and transmission electron microscopy characterizations, it was found that the as-prepared V2O5 spheres are composed of primary nanoparticles with pores between them. The as-prepared hierarchical V2O5 spheres achieved a discharge capacity of 271 mA h g−1 at a current density of 40 mA g−1, and 177 mA h g−1 discharge capacity after 100 cycles. Even at high current densities, V2O5 spheres still delivered high capacity and superior cyclability (179 and 140 mA h g−1 discharge capacities at 640 and 1280 mA g−1 current densities, respectively). The promising electrochemical performances of V2O5 spheres should be ascribed to the unique architecture of hierarchical spheres and the predominant exposed (110) facets, which provides open interlayers for facile sodium ion intercalation. Each nanoparticle contains predominantly exposed (110) crystal planes. The ex situ FESEM analysis revealed that the pores formed by the primary nanocrystals effectively buffer volume changes in the electrode during cycling, contributing to the excellent cycling performance. [ABSTRACT FROM AUTHOR]

Few-layer MoS2 nanosheets are successfully synthesized using a simple and scalable ultrasonic exfoliation technique. The thicknesses of the MoS2 nanosheets ares about 10 nm as measured by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The unique nanosheet architecture renders the high-rate transportation of sodium ions due to the short diffusion paths provided by ultrathin thickness and the large interlayer space within the MoS2 crystal structure ( d(002) = 6.38 Å). When applied as anode materials in sodium-ion batteries, MoS2 nanosheets exhibit a high, reversible sodium storage capacity and excellent cyclability. The MoS2 nanosheets also demonstrate good electrochemical performance at high current densities. [ABSTRACT FROM AUTHOR]

Sodium ion (Na) batteries have attracted increased attention for energy storage owing to the natural abundance and low cost of sodium. Herein, we report the synthesis of mesoporous carbon with large pores as anode for Na-ion batteries. The mesoporous carbon was obtained by carbonization and dense packing of 50 nm resorcinol and formaldehyde spheres synthesized through an extension Stöber method. Our work demonstrates that replacement of lithium by sodium using large pore carbon as anode might offer an alternative route for rechargeable batteries. [ABSTRACT FROM AUTHOR]

Na-ion batteries have been attracting intensive investigations as a possible alternative to Li-ion batteries. Herein, we report the synthesis of SnS2 nanoplatelet@graphene nanocomposites by using a morphology-controlled hydrothermal method. The as-prepared SnS2/graphene nanocomposites present a unique two-dimensional platelet-on-sheet nanoarchitecture, which has been identified by scanning and transmission electron microscopy. When applied as the anode material for Na-ion batteries, the SnS2/graphene nanosheets achieved a high reversible specific sodium-ion storage capacity of 725 mA h g−1, stable cyclability, and an enhanced high-rate capability. The improved electrochemical performance for reversible sodium-ion storage could be ascribed to the synergistic effects of the SnS2 nanoplatelet/graphene nanosheets as an integrated hybrid nanoarchitecture, in which the graphene nanosheets provide electronic conductivity and cushion for the active SnS2 nanoplatelets during Na-ion insertion and extraction processes. [ABSTRACT FROM AUTHOR]

Mesoporous SnO microspheres were synthesised by a hydrothermal method using NaSO4 as the morphology directing agent. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) analyses showed that SnO microspheres consist of nanosheets with a thickness of about 20 nm. Each nanosheet contains a mesoporous structure with a pore size of approximately 5 nm. When applied as anode materials in Na-ion batteries, SnO microspheres exhibited high reversible sodium storage capacity, good cyclability and a satisfactory high rate performance. Through ex situ XRD analysis, it was found that Na+ ions first insert themselves into SnO crystals, and then react with SnO to generate crystalline Sn, followed by Na-Sn alloying with the formation of crystalline NaSn2 phase. During the charge process, there are two slopes corresponding to the de-alloying of Na-Sn compounds and oxidisation of Sn, respectively. The high sodium storage capacity and good electrochemical performance could be ascribed to the unique hierarchical mesoporous architecture of SnO microspheres. [ABSTRACT FROM AUTHOR]

Hollow structured CoFe2O4 nanospheres were synthesized by a hydrothermal method. The uniform hollow nanosphere architecture of the as-prepared CoFe2O4 has been confirmed by field emission scanning electron microscopy and transmission electron microscopy analysis, which give an outer diameter of 200-300 nm and a wall thickness of about 100 nm. CoFe2O4 nanospheres exhibited a high reversible capacity of 1266 mA h g-1 with an excellent capacity retention of 93.6% over 50 cycles and an improved rate capability. CoFe2O4 could be a promising high capacity anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotube/cobalt oxide core-shell one-dimensional nanostructures were prepared via a hydrothermal synthesis method, in which nanosize cobalt oxide crystals were homogeneously coated on the surface of carbon nanotubes. The morphologies and crystal structures of the as-prepared core-shell nanocomposites were analysed by X-ray diffraction, field emission gun scanning electron microscopy, and transmission electron microscopy. When applied as anodes in lithium-ion cells, carbon nanotube/cobalt oxide core-shell nanostructures exhibited an initial lithium storage capacity of 1250mAh/g and a stable capacity of 530mAh/g over 100 cycles. The good electrochemical performance could be attributed to the nanocrystalline cobalt oxide and the unique core-shell one-dimensional nanostructures. [Copyright &y& Elsevier]

Abstract: α-Fe2O3 nanorods were synthesized by a facile hydrothermal method. The as-prepared α-Fe2O3 nanorods have a high quality crystalline nanostructure with diameters in the range of 60–80nm and lengths extending from 300 to 500nm. The crystal structure of the α-Fe2O3 nanorods was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The α-Fe2O3 nanorod anodes exhibit a stable specific capacity of 800mAh/g. This indicates significantly improved electrochemical performance in lithium-ion cells, compared to that of commercial microcrystalline α-Fe2O3 powders. [Copyright &y& Elsevier]

Abstract: Carbon coated magnetite (Fe3O4) core-shell nanorods were synthesized by a hydrothermal method using Fe2O3 nanorods as the precursor. Transmission electron spectroscopy (TEM) and high resolution TEM (HRTEM) analysis indicated that a carbon layer was coated on the surfaces of the individual Fe3O4 nanorods. The electrochemical properties of Fe3O4/carbon nanorods as anodes in lithium-ion cells were evaluated by cyclic voltammetry, ac impedance spectroscopy, and galvanostatic charge/discharge techniques. The as-prepared Fe3O4/C core-shell nanorods show an initial lithium storage capacity of 1120mAh/g and a reversible capacity of 394mAh/g after 100 cycles, demonstrating better performance than that of the commercial graphite anode material. [Copyright &y& Elsevier]

Abstract: Ti6Na2O13·nH2O and Ti6Na2O13 nanowires were synthesized by a hydrothermal method. The synthesized Ti6Na2O13 nanowires were used as anode materials for Li-ion cells to examine Li-storage property. The preliminary result shows that this material exhibited a discharge capacity of 1635mAh/g at first cycle and >1050mAh/g after second cycle. The Ti6Na2O13 nanowire electrode also showed good property retention upon cycling. [ABSTRACT FROM AUTHOR]

Antimony-carbon-graphene fibrous composites were prepared by the electrospinning/spray process as freestanding anodes for sodium-ion batteries. Antimony nanoparticles distribute in conductive carbonized polymer fibers and graphene flakes. The unique structure prevents the aggregation of the antimony nanoparticles and buffers the mechanical stress from volume change of antimony during repeated alloying/de-alloying process. The composites demonstrated an excellent electrochemical performance as anode material for sodium-ion batteries, with a reversible capacity of 274 mAh/g after 100 charge-discharge cycles at a current density of 100 mA/g. [ABSTRACT FROM AUTHOR]

Abstract: Graphene has emerged as an intriguing and attractive functional material for a wide range of applications, owing to its unique physical, chemical and mechanical properties. Herein, we report large-scale production of high quality single crystalline graphene sheets based on the ambient pressure chemical vapor deposition (APCVD) method using acetylene (C2H2) as the carbon source and coral-like iron with body-centered-cubic structure as the catalyst. The process can be scaled up for large quantity production at a low cost. The optimum APCVD temperature has been identified to be 850°C, which is much lower than that catalyzed by other metals. Transmission electron microscopy (TEM), atomic force microscopy, Raman spectroscopy and X-ray photoemission spectroscopy characterizations show the single crystalline and high quality nature of the as-prepared graphene produced by the bottom-up APCVD approach. A new horizontal “dissolution–deposition–growth” mechanism is proposed and verified by high resolution TEM. When applied as anode materials in lithium ion batteries, graphene sheets exhibited a high lithium storage capacity and an excellent cyclability. The capability of preparing crystalline graphene on a large scale with low cost opens an avenue for technological applications of graphene in many fields. [Copyright &y& Elsevier]

Abstract: α-Fe2O3 nanowires were synthesized by a facile hydrothermal method. The crystalline structure and morphology of the synthesized materials have been characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results revealed that the prepared α-Fe2O3 product was uniform nanowires with the length/diameter ratio as high as 500. The electrochemical properties of α-Fe2O3 nanowires were evaluated by cyclic voltammetry (CV) and charge/discharge measurements. The initial charge/discharge capacities can reach 947/1303mAh/g at the rate of 0.1C. The lithium storage capacity maintained 456mAh/g after 100 cycles. This good electrochemical performance may be attributed to the large surface area and short pathways in nanowires for lithium ion migration. [Copyright &y& Elsevier]

Abstract: Graphene–carbon nanotube hybrid materials were successfully prepared through the π–π interaction without using any chemical reagent. We found that the ratio between carbon nanotube and graphene had critical influences on the state in aqueous solution and morphology of hybrid materials. Field emission scanning electron microscope and transmission electron microscope analysis confirmed that graphene nanosheets wrap around individual carbon nanotubes and form a homogeneous three-dimensional hybrid nanostructure. When applied as an anode material in lithium ion batteries, graphene–carbon nanotube hybrid materials demonstrated a high reversible lithium storage capacity, a high Coulombic efficiency and an excellent cyclability. [Copyright &y& Elsevier]

Abstract: MnO/C core–shell nanorods were synthesized by an in situ reduction method using MnO2 nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge–discharge techniques. The as-prepared MnO/C core–shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: An in situ chemical synthesis approach has been developed to prepare SnO2–graphene nanocomposite. Field emission scanning electron microscopy and transmission electron microscopy observation revealed the homogeneous distribution of SnO2 nanoparticles (4–6nm in size) on graphene matrix. The electrochemical reactivities of the SnO2–graphene nanocomposite as anode material were measured by cyclic voltammetry and galvanostatic charge/discharge cycling. The as-synthesized SnO2–graphene nanocomposite exhibited a reversible lithium storage capacity of 765mAh/g in the first cycle and an enhanced cyclability, which can be ascribed to 3D architecture of the SnO2–graphene nanocomposite. [Copyright &y& Elsevier]

The combination of nitrogen doped mesoporous layered structure derived from C 3 N 4 and ultrasmall amorphous Sb enables excellent sodium storage performance. • A novel hybrid containing amorphous Sb and N-doped layered carbon was fabricated. • The amorphous Sb and mesoporous channels endow the hybrid with improved dynamics. • Superior cycling stability and remarkable rate capability are achieved for SIBs. Antimony (Sb) based materials, which have been proved to be promising anodes to fabricate high-performance sodium-ion batteries (SIBs), have attracted considerable interest owing to its large theoretical capacity (660 mAh g−1), appropriate inserting potential of sodium (0.5–0.8 V vs Na+/Na), and moderate electrode polarization (~0.35 V). Unfortunately, fast capacity decay and serious structure pulverization resulting from large volume variation upon cycling are often observed for Sb-based anodes, and further structure design is needed. In this work, a novel hybrid of amorphous Sb/N-doped layered carbon (a-Sb/NC) was fabricated through a facile bottom-up method, where ultrafine amorphous Sb nanoparticles are uniformly anchored on layered N-doped carbon (NC). When applied as anode material for SIBs, this hybrid exhibits a large reversible capacity (479.6 mAh g−1 at 0.1 A g−1 up to 100 cycles), robust rate capability (298.7 mAh g−1 at current density of 2 A g−1), and remarkable stability upon long-term cycling (280.5 mAh g−1 at 1.0 A g−1 up to 500 cycles), outperforming most of the reported amorphous anodes for SIBs. In principle, such impressive sodium storage properties of a-Sb/NC should be mainly ascribed to the amorphous feature of Sb nanoparticles as well as the synergistic effect between amorphous Sb and layered NC, thereby endowing the composite with improved electron/ion dynamics and efficient self-buffering ability. [ABSTRACT FROM AUTHOR]

• Highly flexible CNT scaffolds were prepared and firstly used to stabilize Zn anodes. • The CNT scaffold-stabilized Zn anodes displayed superior cycling stability. • Ultralong-life zinc-ion batteries/hybrid capacitors with Zn anodes were constructed. The merits of zinc metal anodes such as high chemical stability, low cost and ultrahigh volumetric capacity endow Zn based batteries/hybrid capacitors with great potential applications for electronic products. However, unstable stripping/plating of zinc anodes tends to cause the formation of protuberances/dendrites and side reactions such as water decomposition on anode surfaces, eventually leading to the failure of Zn based electrochemical energy storage devices. Herein, we report the fabrication of free-standing, highly flexible and conductive carbon nanotube (CNT)/paper scaffolds to stabilize zinc metal anodes. The free-standing CNT scaffolds only need to be placed between zinc anodes and separators when assembling zinc anode-based batteries/hybrid capacitors. On the surface of the zinc electrode, the scaffolds' porous skeleton mechanically regulates Zn2+ deposition sites and their conductive CNT networks maintain a stable electric field during Zn stripping/plating processes, thus retarding the formation of protuberances/dendrites and the occurrence of side reactions. The scaffold-stabilized zinc anodes displayed small polarization voltages, a long cycling life over 1800 h and superior capability for fast charging-discharging. In addition, benefiting from the high electrochemical stability and reversibility of the scaffold-stabilized zinc anodes, zinc-ion batteries/hybrid capacitors with ultralong cycle lives were successfully constructed. This work provides a scalable approach to stabilize zinc metal anodes for long-life zinc-ion batteries and zinc-ion hybrid capacitors. [ABSTRACT FROM AUTHOR]