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Crystalline Ni3Si2 nanostructures were grown on nickel foams via a simple and high-yield chemical vapor deposition (CVD). The morphologies were found to be dependent on the growth pressure. The obtained nanostructures have good crystallinity and uniform distribution. After coating amorphous silicon (a-Si) layers onto the obtained Ni3Si2 nanostructures by an inductively coupled plasma CVD, the architectures were assembled as anodes for lithium-ion batteries. High initial reversible specific capacity of 3733 mA h g−1 is obtained for the prepared a-Si coated Ni3Si2 nanowire electrode at a current density of 2.1 A g−1. After 50 cycles, the specific capacity still stays at above 2000 mA h g−1. When the current density is as high as 8.4 A g−1, the specific capacity maintains at about 1500 mA h g−1. For such core–shell configuration electrodes, the inactive and metallic Ni3Si2 core conducts electrons and provides a mechanically stable anchoring basis for the a-Si layers, resulting in improved electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, 2D nanosheets or nanoplatelets have attracted great attention due to their wide applications. However, the synthesis of 2D α-Fe2O3 nanosheets with well-defined hexagonal shape is extremely challenging, because the selective growth along one specific facet is very hard to be realized. In our work, we studied the non-capping ligand mediated reaction within graphene layer chamber, and successfully synthesized α-Fe2O3 hexagonal nanoplatelets sandwiched between graphene layers (HP-Fe–G). These materials exhibit an improved electrochemical performance compared with the pre-existing α-Fe2O3 nanoparticles loaded graphene (G-Fe2O3) composites because of the uniqueness of such architectures: thin nanoplatelets, large enough sandwiched spaces to buffer the volume expansion and N-doped graphene. HP-Fe–G delivered an ultrahigh reversible capacity of 1100mAh/g after 50 cycles, thus higher than their theoretical value (926mAh/g); while G-Fe2O3 composites showed relatively low capacity retention even after only 20 cycles (582mAh/g). In addition, HP-Fe–G also reveal superior rate capability, 887mAh/g at 1C; in comparison, this value was only 135mAh/g at 1C for G-Fe2O3. [Copyright &y& Elsevier]

Molybdenum disulfide nanosheets@hollow nitrogen-doped carbon (MoS 2 @NC) spheres were prepared via a facile synthesis and investigated as a host material for ion storages. When used in lithium ion batteries (LIBs) or sodium ion batteries (SIBs), the MoS 2 @NC spheres electrodes exhibited excellent electrochemical performances. A high capacity of 1386 mAh g −1 after 100 cycles was obtained at a current density of 200 mA g −1 for LIBs. As for SIBs, a capacity of 330 mAh g −1 was retained after 400 cycles at 1000 mA g −1 . The remarkable ion storage performances can be attributed to the hierarchical architecture of the MoS 2 @NC spheres, which not only supply abundant active sites and efficient electron and ion pathways, but also alleviate the volume change of the active MoS 2 material. Meanwhile, synergistic effect of the heterogeneous components, interfacial ion storages, nitrogen doping and induced defects are responsible for high capacities of the MoS 2 @NC electrodes. And the electrodes exhibited enhanced electrochemical kinetics due to the significantly improved electrical conductivity and the large specific area of the MoS 2 @NC spheres. [ABSTRACT FROM AUTHOR]

Composites of graphene-wrapped Si nanoparticles (NPs) have been assembled via a one-pot liquid nitrogen fast freezing followed by a thermal reduction. It is found that, as a self-support and binder-free anode of lithium-ion battery, the composited graphene is helpful to form a uniform morphology, reduce the resistance of the electrode and isolate the Si NPs from the electrolyte to suppress the formation of unstable solid electrolyte interphase. Moreover, it can buffer the strain from the volume change of the Si NPs. The composite with an optimized mass ratio of reduced graphene oxide (rGO) to Si NPs exhibits significantly improved lithium storage performance with an excellent rate capability and a large reversible capacity of 1482 mAh g −1 at a current density of 210 mA g −1 after 300 cycles. Furthermore, the electrochemical reaction kinetics and interfacial behavior of the rGO/Si composites are investigated in-depthly. The work reported here can be extended to the fabrication of the other graphene-based materials. [ABSTRACT FROM AUTHOR]

Co 3 O 4 has been always highlighted as an anode material for lithium ion batteries (LIBs) due to its high theoretical capacity and low cost. However, its practical application is severely limited by the inherent structural pulverization and activation hysteresis during cycling. To overcome such limitation, in this work, a facile route of air-injection assisted soaking in dopamine-tris (DA-tris) solution followed by annealing in Ar atmosphere is successfully approached to decorate N-doped amorphous carbon (a-C) shells on surface of Co 3 O 4 microspheres. The N-doped a-C shells are co-constructed by films and nanoparticles of N-doped a-C. The concentration of DA-tris plays significant roles to the structural nature of the N-doped a-C shells and the phase configuration of the Co 3 O 4 microspheres. As an anode material for LIBs, the Co 3 O 4 microspheres decorated by the N-doped a-C shells exhibit superior reversible capabilities of 1074 mA h g −1 under 500 mA g −1 and 830 mA h g −1 under 1000 mA g −1 after 500 cycles, respectively. Moreover, the rate capacity is impressive and the activation hysteresis is remitted effectively. Such an excellent lithium ions storage performance is firstly ascribed to the rapid activation of Co 3 O 4 promoted by metallic Co, which is reduced by the N-doped a-C shells in situ. Secondly, the N-doped a-C shells effectively protect the structure from cracking and promote the electrochemical reactions of the Co 3 O 4 microspheres. The present work provides an effective way to buffer the activation hysteresis of the transition metal oxides used for advanced LIBs application. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries have attracted extensive interest due to their higher theoretical energy density than the current commercial lithium-ion batteries. However, their practical application is largely hindered by the low sulfur utilization and poor cycling stability. Restraining the shuttle effect and enhancing the electrochemical kinetics are important for developing high-performance Li-S batteries. Here we use carbon nanofibers (CNFs) supported manganese dioxide (MnO 2 ) composite as a bifunctional coating on sulfur cathode for anchoring polysulfides and accelerating their redox reactions simultaneously. The CNFs/MnO 2 composite supplies fast paths for electron transfer and ion diffusion, and greatly promotes the transformation processes of polysulfides to Li 2 S/Li 2 S 2 , leading to an enhanced electrochemical kinetics. The diffusion coefficient of lithium ion has been increased by 560%. As a result, the CNFs/MnO 2 composite covered electrode exhibits an excellent cycling stability, its specific capacity maintains at about 600 mAh g −1 at 1C after 400 cycles, corresponding to a capacity decay as low as 0.063% per cycle, and the average coulombic efficiency reaches up to 99.66%. [ABSTRACT FROM AUTHOR]

The rock-salt structural manganous sulfide (α-MnS) is of higher lithium storage capacity. To improve the cyclability of α-MnS anode in lithium-ion batteries, we prepared a composite of α-MnS nanocrystallites grown on nitrogen and sulfur co-doped reduced graphene oxide (rGO) honeycomb framework. N and S atoms have been co-doped into rGO along with the growth of the α-MnS nanocystallites by a one-pot hydrothermal synthesis using thiourea as dopant and reactant. The typical α-MnS/N S co-doped rGO (NSG) composite electrode exhibits a reversible capacity as high as 763.5 mAh g −1 after 100 cycles at 100 mA g −1 , and a reversible capacity of 576.7 mAh g −1 even after 2000 cycles at 1000 mA g −1 . More importantly, the α-MnS/NSG composite electrodes show superior cycle performance at asymmetric discharge/charge current densities. The excellent electrochemical performance can be attributed to that the α-MnS nanocrystallites shorten lithium ion transmission distance, N-S co-doping improves the electronic conductivity of rGO, and the formation of chemical bonds combination between α-MnS and NSG enhances the electrode structural stability and the electron transport. In addition, more stable architecture of NSG-supported ultrafine α-MnS particles is formed upon cycling, which greatly enhances the electrical contact and further improves the electrochemical performance. [ABSTRACT FROM AUTHOR]

Silicon is the most promising anode material for the next-generation lithium-ion batteries (LIBs). However, the large volume change during lithiation/delithiation and low intrinsic conductivity hamper its electrochemical performance. Here we report a well-designed LIB anode in which carbon-coated Si nanoparticles/reduced graphene oxide (Si/rGO) multilayer was anchored to nanostructured current collector with stable mechanical support and rapid electron conduction. Furthermore, we improved the integral stability of the electrode through introducing amorphous carbon. The designed anode exhibits superior cyclability, its specific capacity remains above 800 mAh g −1 after 350 cycles at a current density of 2.0 A g −1 . The excellent electrochemical performance can be attributed to the fact that the Si/rGO multilayer is reinforced by the nanostructured current collector and the formed amorphous carbon, which can maintain the structural and electrical integrities of the electrode. [ABSTRACT FROM AUTHOR]

Carbon-wrapped MnO nanodendrites interspersed on reduced graphene oxide sheets (C-MnO/rGO) were prepared on nickel foam by a facile vacuum filtration and a subsequent thermal treatment. As a binder-free anode of lithium-ion battery, the nanodendritic structure of C-MnO accommodates the huge volume expansion and shortens the diffusion length for lithium ion and electron, rGO sheets prevent C-MnO nanodendites from aggregation and offer a good electronic conduction. As a result, the electrode with such a novel architecture delivers superior electrochemical properties including high reversible capacity, excellent rate capability and cycle stability. Moreover, MnO nanodendrites change to nanoparticles wrapped in graphene sheets during the lithiation/delithiation process, which is a more beneficial microstructure to further increase the specific capacity and cycle life of the electrode. [ABSTRACT FROM AUTHOR]

The core-shell structural Fe 3 O 4 @C nanospheres have been facilely fabricated using ferrocene as a starting material.(*) The obtained architecture shows unique morphology and, as an anode of half cell lithium-ion batteries, delivers an initial coulombic efficiency as high as 80% and a high reversible capacity of 736 mAh g −1 at 0.3 A g −1 after 80 cycles. Even at an ultrahigh current density of 10 A g −1 , the reversible capacity is 234 mAh g −1 . Also, Fe 3 O 4 @C nanospheres electrode was paired with commercial LiCoO 2 electrode to design a novel full cell, which shows a superior electrochemical performance. [ABSTRACT FROM AUTHOR]

Despite their potential application in lithium-ion battery electrodes, one apparent disadvantage for SnO 2 -based materials is that the electrodes suffer low coulombic efficiency especially for the initial cycle, which originates from the irreversible conversion of SnO 2 to Sn, the formation of solid electrolyte interphase and the other possible side reactions. Here we design a novel nanofiber structure in which SnO 2 nanoparticles are well separated and confined by inner porous carbon framework and then hooped by outer carbon shell. The resultant SnO 2 /voids@C nanofibers electrode displays not only a high reversible capacity of 986 mAh g −1 at 200 mA g −1 after 200 cycles, but also a high initial coulombic efficiency of 73.5%. It has been shown that such a rational design can efficiently reduce the side reactions and promote the reversible conversion of Sn to SnO 2 for both half and full cells. [ABSTRACT FROM AUTHOR]

Lithiated-CuO nanorods were used as a nanostructured electronic-conductor of the current-collector for Ge anode to improve the performance of lithium-ion batteries. By limiting the voltage cut-off window in a range which could avoid the discharge–charge plateaus of CuO after the initial discharge, the lithiated-CuO nanorods can act as an electronic-conductor. The obtained Ge anode exhibits an excellent rate capability and superior cyclability. At a current-density of 1 A/g, the anode presents a capacity retention of above 95% even after 100 cycles. The anode also presents a stable rate performance even at a current-density as high as 10 A/g. The enhanced performance can be mainly ascribed to the lithiated-CuO nanorods which could result in a nanocable structure that offers short electron/lithium-ion transport path, enough buffering space for the huge volume change of Ge coating and excellent electrical contact between the Ge coating and the current-collector. [ABSTRACT FROM AUTHOR]

• A strategy can control the specific capacity of electrode and reduce the use of high cost active materials in applications. • The prepared Si/PC nanoparticles buffer the effect of silicon volume expansion while improve the diffusion of lithium ions. • The prepared hybrid electrode and full cell have an excellent electrochemical performance. [Display omitted] Silicon-based materials are expected to be the next generation of anode materials for lithium-ion batteries (LIBs). However, the electrode structure will be damaged due to large volume expansion during the lithiation process, resulting in a rapid decay of the battery performance. Nanostructures, porous structures, and carbon coatings have been shown to be effective in reducing the effect of volume expansion. In this work, porous carbon coated silicon (Si/PC) nanoparticles were prepared to suppress the effect of silicon volume expansion while improve the infiltration of electrolyte and the diffusion of lithium ions. The prepared Si/PC nanoparticles were mixed with commercial graphite in different mass ratios as anode materials for LIBs, which can effectively control the specific capacities of the anodes and help the practical applications by reducing the production cost. As the mass ratio of the prepared Si/PC nanoparticles to commercial graphite is 2:1, the first discharge specific capacity is 1586.3 mA h g−1 with an initial coulombic efficiency of 82.1% at a current density of 200 mA g−1. After 250 cycles at 1000 mA g−1, the capacity retention rate is 86.8%. The full cell with LiNi 0.8 Mn 0.1 Co 0.1 O 2 as cathode shows an excellent cycle stability with a high stack cell energy density of 882.3 Wh/L. [ABSTRACT FROM AUTHOR]

Distinctfrom pure graphene, N-doped graphene (GN) has been foundto possess high rate capability and capacity for lithium storage.However, there has still been a lack of direct experimental evidenceand fundamental understanding of the storage mechanisms at the atomicscale, which may shed a new light on the reasons of the ultrafastlithium storage property and high capacity for GN. Here we reporton the atomistic insights of the GN energy storage as revealed byin situ transmission electron microscopy (TEM). The lithiation processon edges and basal planes is directly visualized, the pyrrolic N “hole”defect and the perturbed solid-electrolyte-interface configurationsare observed, and charge transfer states for three N-existing formsare also investigated. In situ high-resolution TEM experiments togetherwith theoretical calculations provide a solid evidence that enlargededge {0002} spacings and surface hole defects result in improved surfacecapacitive effects and thus high rate capability and the high capacityare owing to short-distance orderings at the edges during dischargingand numerous surface defects; the phenomena cannot be understood previouslyby standard electron or X-ray diffraction analyses. [ABSTRACT FROM AUTHOR]

Abstract: Functional Cu nanorods supported P-doped Si anode was designed to improve the performance of lithium-ion batteries for high-power applications. The binder-free anode consists of an electrochemical etched Cu nanorod network coated with P-doped Si. The obtained electrode exhibits excellent rate capability and superior cyclability. At a rate of 2A/g, the anode presents a capacity of 2010mAh/g even after 80 cycles with a capacity retention of above 80%. The anode also presents a stable rate performance even at a high rate of 10A/g. The enhanced performance can be mainly ascribed to the Cu nanorod network which could result in a nanocable structure on the micro-level and play a role of scaffolding on the macro-level, as well as the nature of high conductivity and amorphism of the heavy P-doped Si coating. [Copyright &y& Elsevier]

A novel Si film with Si nanocrystals embedded in amorphous Si matrix was grown on Cu foil via an inductively coupled plasma-enhanced chemical vapor deposition and subsequent electron beam irradiation. The Si nanocrystals show spherical morphology with rich defects and the mean size is about 6 nm. The electrochemical performance of the obtained Si as anode for lithium ion batteries was studied via conventional charge/discharge test, which shows distinct improvement on cycle performance compared with that of amorphous Si obtained without electron beam irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Si–Ni nanorod structures as anode materials for Li ion batteries have been prepared by depositing Si coatings on electrodeposited Ni nanocone arrays using plasma enhanced chemical vapor deposition. The obtained samples were characterized by field emission scanning electron microscopy and X-ray diffraction. The electrochemical performance was evaluated by a galvanostatic battery testing. It is shown that the first discharge capacity is high as 4125mAh/g with a high first coulombic efficiency of 92% at C/20 rate. A capacity of 3249mAh/g at C/5 rate is attained with retention of 95.7% after 30cycles. [Copyright &y& Elsevier]

Abstract: Germanium coatings as an anode material of lithium-ion batteries have been deposited on electrodeposited nickel nanocone-arrays by very high frequency plasma enhanced chemical vapor deposition. The morphologies of the obtained nanostructures were characterized by field emission scanning electron microscopy in detail. The electrochemical performance was evaluated by a galvanostatic battery testing. It was shown that the anode exhibits a stable capacity of 590mAh/g at a rate of C/10. A reversible specific capacity is retained to be 468 mAh/g at a rate of C/2 after 50 cycles, which is close to the value of the second cycle. [Copyright &y& Elsevier]