N-doped amorphous carbon coated Fe3O4/SnO2 coaxial nanofibers as a binder-free self-supported electrode for lithium ion batteries

N-doped amorphous carbon coated Fe3O4/SnO2 coaxial nanofibers were prepared via a facile approach. The core composite nanofibers were first made by electrospinning technology, then the shells were conformally coated using the chemical bath deposition and subsequent carbonization with polydopamine as a carbon source. When applied as a binder-free self-supported anode for lithium ion batteries, the coaxial nanofibers displayed an enhanced electrochemical storage capacity and excellent rate performance. The morphology of the interwoven nanofibers was maintained even after the rate cycle test. The superior electrochemical performance originates in the structural stability of the N-doped amorphous carbon shells formed by carbonizing polydopamine.

Template-free electrochemical synthesis of Sn nanofibers as high-performance anode materials for Na-ion batteries

Sn nanofibers with a high aspect ratio are successfully synthesized using a simple electrodeposition process from an aqueous solution without the use of templates. The synthetic approach involves the rapid electrochemical deposition of Sn accompanied by the strong adsorption of Triton X-100, which can function as a growth modifier for the Sn crystallites. Triton X-100 is adsorbed on the {200} crystallographic planes of Sn in an elongated configuration and suppressed the preferential growth of Sn along the [100] direction. Consequently, the Sn electrodeposits are forced to grow anisotropically in a direction normal to the (112) or (1̅12) plane, forming one-dimensional nanofibers. As electrode materials for the Na-ion batteries, the Sn nanofibers exhibit a high reversible capacity and an excellent cycle performance; the charge capacity is maintained at 776.26 mAh g(-1) after 100 cycles, which corresponds to a retention of 95.09% of the initial charge capacity. The superior electrochemical performance of the Sn nanofibers is mainly attributed to the high mechanical stability of the nanofibers, which originate from highly anisotropic expansion during sodiation and the pore volumes existing between the nanofibers.

Cobalt carbonate/ and cobalt oxide/graphene aerogel composite anodes for high performance Li-ion batteries

Nanocomposites consisting of ultrafine, cobalt carbonate nanoneedles and 3D porous graphene aerogel (CoCO3/GA) are in situ synthesized based on a one-step hydrothermal route followed by freeze-drying. A further heat treatment produces cobalt oxide nanoparticles embedded in the conductive GA matrix (Co(3)O(4)/GA). Both the composite anodes deliver excellent specific capacities depending on current density employed: the CoCO(3)/GA anode outperforms the Co(3)O(4)/GA anode at low current densities, and vice versa at current densities higher than 500 mA g(-1). Their electrochemical performances are considered among the best of similar composite anodes consisting of CoCO(3) or Co(3)O(4) active particles embedded in a graphene substrate. The stable multistep electrochemical reactions of the carbonate compound with a unique nanoneedle structure contribute to the excellent cyclic stability of the CoCO(3)/GA electrode, whereas the highly conductive networks along with low charge transfer resistance are responsible for the high rate performance of the Co(3)O(4)/GA electrode.

Multishelled TiO2 hollow microspheres as anodes with superior reversible capacity for lithium ion batteries

Herein, uniform multishelled TiO2 hollow microspheres were synthesized, especially 3- and 4-shelled TiO2 hollow microspheres were synthesized for the first time by a simple sacrificial method capable of controlling the shell thickness, intershell spacing, and number of internal multishells, which are achieved by controlling the size, charge, and diffusion rate of the titanium coordination ions as well as the calcination process. Used as anodes for lithium ion batteries, the multishelled TiO2 hollow microspheres show excellent rate capacity, good cycling performance, and high specific capacity. A superior capacity, up to 237 mAh/g with minimal irreversible capacity after 100 cycles is achieved at a current rate of 1 C (167.5 mA/g), and a capacity of 119 mAh/g is achieved at a current rate of 10 C even after 1200 cycles.

Reversible conversion-alloying of Sb2O3 as a high-capacity, high-rate, and durable anode for sodium ion batteries

Sodium ion batteries are attracting ever-increasing attention for the applications in large/grid scale energy storage systems. However, the research on novel Na-storage electrode materials is still in its infancy, and the cycling stability, specific capacity, and rate capability of the reported electrode materials cannot satisfy the demands of practical applications. Herein, a high performance Sb(2)O(3) anode electrochemically reacted via the reversible conversion-alloying mechanism is demonstrated for the first time. The Sb(2)O(3) anode exhibits a high capacity of 550 mAh g(-1) at 0.05 A g(-1) and 265 mAh g(-1) at 5 A g(-1). A reversible capacity of 414 mAh g(-1) at 0.5 A g(-1) is achieved after 200 stable cycles. The synergistic effect involving conversion and alloying reactions promotes stabilizing the structure of the active material and accelerating the kinetics of the reaction. The mechanism may offer a well-balanced approach for sodium storage to create high capacity and cycle-stable anode materials.

New synthesis of a Foamlike Fe3O4/C composite via a self-expanding process and its electrochemical performance as anode material for lithium-ion batteries

A novel foamlike Fe3O4/C composite is prepared via a sol-gel type method with gelatin as the carbon source and ferric nitrate as the iron source, following a postannealing treatment. Its lithium storage properties as anode material for a lithium-ion battery are thoroughly investigated in this work. With the interaction between ferric nitrate and gelatin, the foamlike architecture is attained through a unique self-expanding process. The Fe3O4/C composite possesses abundant porous structure along with highly dispersed Fe3O4 nanocrystal embedment in the carbon matrix. In the constructed architecture, the 3D porous network property ensures electrolyte accessibility; meanwhile, nanosized Fe3O4 promotes lithiation/delithiation, owing to numerous active sites, large electrolyte contact area, and a short lithium ion diffusion path. As a result, this Fe3O4/C composite electrode demonstrates an excellent cycling stability with a reversible capacity of 1008 mA h g(-1) over 400 cycles at 0.2C (1C = 1000 mA g(-1)), as well as a superior rate performance with reversible capacity of 660 and 580 mA h g(-1) at 3C and 5C, respectively.

Nanoparticulate Mn3O4/VGCF composite conversion-anode material with extraordinarily high capacity and excellent rate capability for lithium ion batteries

In this work, highly conductive vapor grown carbon fiber (VGCF) was applied as an electrically conductive agent for facile synthesis of a nanoparticulate Mn3O4/VGCF composite material. This material exhibits super high specific capacity and excellent rate capability as a conversion-anode for lithium ion batteries. Rate performance test result demonstrates that at the discharge/charge current density of 0.2 A g(-1) a reversible capacity of ca. 950 mAh g(-1) is delivered, and when the current rate is increased to a high current density of 5 A g(-1), a reversible capacity of ca. 390 mAh g(-1) is retained. Cyclic performance examination conducted at the current density of 0.5 A g(-1) reveals that in the initial 20 cycles the reversible capacity decreases gradually from 855 to 747 mAh g(-1). However, since then, it increases gradually with cycle number increasing, and after 200 cycles an extraordinarily high reversible capacity of 1391 mAh g(-1) is achieved.

Synthesis of hierarchically porous SnO(2) microspheres and performance evaluation as li-ion battery anode by using different binders

We have prepared nanoporous SnO2 hollow microspheres (HMS) by employing the resorcinol-formaldehyde (RF) gel method. Further, we have investigated the electrochemical property of SnO2-HMS as negative electrode material in rechargeable Li-ion batteries by employing three different binders-polyvinylidene difluoride (PVDF), Na salt of carboxy methyl cellulose (Na-CMC), and Na-alginate. At 1C rate, SnO2 electrode with Na-alginate binder exhibits discharge capacity of 800 mA h g(-1), higher than when Na-CMC (605 mA h g(-1)) and PVDF (571 mA h g(-1)) are used as binders. After 50 cycles, observed discharge capacities were 725 mA h g(-1), 495 mA h g(-1), and 47 mA h g(-1), respectively, for electrodes with Na-alginate, Na-CMC, and PVDF binders that amounts to a capacity retention of 92%, 82%, and 8% . Electrochemical impedance spectroscopy (EIS) results confirm that the SnO2 electrode with Na-alginate as binder had much lower charge transfer resistance than the electrode with Na-CMC and PVDF binders. The superior electrochemical property of the SnO2 electrode containing Na-alginate can be attributed to the cumulative effects arising from integration of nanoarchitecture with a suitable binder; the hierarchical porous structure would accommodate large volume changes during the Li interaclation-deintercalation process, and the Na-alginate binder provides a stronger adhesion betweeen electrode film and current collector.

Synthesis and extreme rate capability of Si-Al-C-N functionalized carbon nanotube spray-on coatings as Li-ion battery electrode

Silicon-based precursor derived glass-ceramics or PDCs have proven to be an attractive alternative anode material for Li ion batteries. Main challenges associated with PDC anodes are their low electrical conductivity, first cycle loss, and meager C-rate performance. Here, we show that thermal conversion of single source aluminum-modified polysilazane on the surfaces of carbon nanotubes (CNTs) results in a robust Si-Al-C-N/CNT shell/core composite that offers extreme C-rate capability as battery electrode. Addition of Al to the molecular network of Si-C-N improved electrical conductivity of Si-C-N by 4 orders of magnitude, while interfacing with CNTs showed 7-fold enhancement. Further, we present a convenient spray-coating technique for PDC composite electrode preparation that eliminates polymeric binder and conductive agent there-by reducing processing steps and eradicating foreign material in the electrode. The Si-Al-C-N/CNT electrode showed stable charge capacity of 577 mAh g(-1) at 100 mA g(-1) and a remarkable 400 mAh g(-1) at 10,000 mA g(-1), which is the highest reported value for a silazane derived glass-ceramic or nanocomposite electrode. Under symmetric cycling conditions, a high charge capacity of ∼350 mA g(-1) at 1600 mA g(-1) was continuously observed for over 1000 cycles.

Enhancing the Li storage capacity and initial coulombic efficiency for porous carbons by sulfur doping

Here, we report a new approach to synthesizing S-doped porous carbons and achieving both a high capacity and a high Coulombic efficiency in the first cycle for carbon nanostructures as anodes for Li ion batteries. S-doped porous carbons (S-PCs) were synthesized by carbonization of pitch using magnesium sulfate whiskers as both templates and S source, and a S doping up to 10.1 atom % (corresponding to 22.5 wt %) was obtained via a S doping reaction. Removal of functional groups or highly active C atoms during the S doping has led to formation of much thinner solid-electrolyte interface layer and hence significantly enhanced the Coulombic efficiency in the first cycle from 39.6% (for the undoped porous carbon) to 81.0%. The Li storage capacity of the S-PCs is up to 1781 mA h g(-1) at the current density of 50 mA g(-1), more than doubling that of the undoped porous carbon. Due to the enhanced conductivity, the hierarchically porous structure and the excellent stability, the S-PC anodes exhibit excellent rate capability and reliable cycling stability. Our results indicate that S doping can efficiently promote the Li storage capacity and reduce the irreversible Li combination for carbon nanostructures.

Sodium/Lithium storage behavior of antimony hollow nanospheres for rechargeable batteries

Sodium-ion batteries (SIBs) have come up as an alternative to lithium-ion batteries (LIBs) for large-scale applications because of abundant Na storage in the earth's crust. Antimony (Sb) hollow nanospheres (HNSs) obtained by galvanic replacement were first applied as anode materials for sodium-ion batteries and exhibited superior electrochemical performances with high reversible capacity of 622.2 mAh g(-1) at a current density of 50 mA g(-1) after 50 cycles, close to the theoretical capacity (660 mAh g(-1)); even at high current density of 1600 mA g(-1), the reversible capacities can also reach 315 mAh g(-1). The benefits of this unique structure can also be extended to LIBs, resulting in reversible capacity of 627.3 mAh g(-1) at a current density of 100 mAh g(-1) after 50 cycles, and at high current density of 1600 mA g(-1), the reversible capacity is 435.6 mAhg(-1). Thus, these benefits from the Sb HNSs are able to provide a robust architecture for SIBs and LIBs anodes.

A new benchmark capacitance for supercapacitor anodes by mixed-valence sulfur-doped V6O(13-x)

A new pseudocapacitor anode, sulfur-doped V6O(13-x), is reported. It achieves a benchmark capacitance of 1353 F/g (0.72 F/cm(2)) at a current density of 1.9 A/g (1 mA/cm(2)) in 5 M LiCl solution. The charges are stored chemically in the electrode via reversible redox reactions that involve multiple oxidation states of vanadium (V(3+), V(4+) and V(5+)).

Silicon decorated cone shaped carbon nanotube clusters for lithium ion battery anodes

In this work, we report the synthesis of an three-dimensional (3D) cone-shape CNT clusters (CCC) via chemical vapor deposition (CVD) with subsequent inductively coupled plasma (ICP) treatment. An innovative silicon decorated cone-shape CNT clusters (SCCC) is prepared by simply depositing amorphous silicon onto CCC via magnetron sputtering. The seamless connection between silicon decorated CNT cones and graphene facilitates the charge transfer in the system and suggests a binder-free technique of preparing lithium ion battery (LIB) anodes. Lithium ion batteries based on this novel 3D SCCC architecture demonstrates high reversible capacity of 1954 mAh g(-1) and excellent cycling stability (>1200 mAh g(-1) capacity with ≈ 100% coulombic efficiency after 230 cycles).

Electrical and Mechanical Performance of Carbon Fiber-Reinforced Polymer Used as the Impressed Current Anode Material

An investigation was performed by using carbon fiber-reinforced polymer (CFRP) as the anode material in the impressed current cathodic protection (ICCP) system of steel reinforced concrete structures. The service life and performance of CFRP were investigated in simulated ICCP systems with various configurations. Constant current densities were maintained during the tests. No significant degradation in electrical and mechanical properties was found for CFRP subjected to anodic polarization with the selected applied current densities. The service life of the CFRP-based ICCP system was discussed based on the practical reinforced concrete structure layout.

Hierarchically designed SiOx/SiOy bilayer nanomembranes as stable anodes for lithium ion batteries

Hierarchically designed SiOx /SiOy rolled-up bilayer nanomembranes are used as anodes for lithium-ion batteries. The functionalities of the SiO(x,y) layers can be engineered by simply controlling the oxygen content, resulting in anodes that exhibit a reversible capacity of about 1300 mA h g(-1) with an excellent stability of over 100 cycles, as well as a good rate capability.

Tin phosphide as a promising anode material for Na-ion batteries

Sn4 P3 is introduced for the first time as an anode material for Na-ion batteries. Sn4 P3 delivers a high reversible capacity of 718 mA h g(-1), and shows very stable cycle performance with negligible capa-city fading over 100 cycles, which is attributed to the confinement effect of Sn nanocrystallites in the amorphous phosphorus matrix during cycling.

[NiFe]Hydrogenase from Citrobacter sp. S-77 surpasses platinum as an electrode for H2 oxidation reaction

Reported herein is an electrode for dihydrogen (H2) oxidation, and it is based on [NiFe]Hydrogenase from Citrobacter sp. S-77 ([NiFe]S77). It has a 637 times higher mass activity than Pt (calculated based on 1 mg of [NiFe]S77 or Pt) at 50 mV in a hydrogen half-cell. The [NiFe]S77 electrode is also stable in air and, unlike Pt, can be recovered 100 % after poisoning by carbon monoxide. Following characterization of the [NiFe]S77 electrode, a fuel cell comprising a [NiFe]S77 anode and Pt cathode was constructed and shown to have a a higher power density than that achievable by Pt.

Performance of Solid Oxide Fuel Cell With La and Cr Co-doped SrTiO3 as Anode

The La_0.3Sr_0.55Ti_0.9Cr_0.1O_3-δ (LSTC10) anode material was synthesized by citric acid-nitrate process. The yttria-stabilized zirconia (YSZ) electrolyte-supported cell was fabricated by screen printing method using LSTC10 as anode and (La_0.75Sr_0.25)_0.95MnO_3-δ (LSM) as cathode. The electrochemical performance of cell was tested by using dry hydrogen as fuel and air as oxidant in the temperature range of 800-900 °C. At 900 °C, the open circuit voltage (OCV) and the maximum power density of cell are 1.08 V and 13.0 mW·cm^-2, respectively. The microstructures of cell after performance testing were investigated by scanning electron microscope (SEM). The results show that the anode and cathode films are porous and closely attached to the YSZ electrolyte. LSTC10 is believed to be a kind of potential solid oxide fuel cell (SOFC) anode material.

Graphite/silicon hybrid electrodes using a 3D current collector for flexible batteries

A flexible hybrid anode from graphite and thin film silicon is realized by the concept of a 3D sandwich current collector by the combination of micro-contact printing and RF magnetron sputtering. Flexible lithium-ion batteries with a new hybrid anode demonstrate not only enhanced specific capacity but also improved rate capability compared to that of a conventional graphite anode under bending deformation.

Three-dimensional nanoporous Fe₂O₃/Fe₃C-graphene heterogeneous thin films for lithium-ion batteries

Three-dimensional self-organized nanoporous thin films integrated into a heterogeneous Fe2O3/Fe3C-graphene structure were fabricated using chemical vapor deposition. Few-layer graphene coated on the nanoporous thin film was used as a conductive passivation layer, and Fe3C was introduced to improve capacity retention and stability of the nanoporous layer. A possible interfacial lithium storage effect was anticipated to provide additional charge storage in the electrode. These nanoporous layers, when used as an anode in lithium-ion batteries, deliver greatly enhanced cyclability and rate capacity compared with pristine Fe2O3: a specific capacity of 356 μAh cm(-2) μm(-1) (3560 mAh cm(-3) or ∼1118 mAh g(-1)) obtained at a discharge current density of 50 μA cm(-2) (∼0.17 C) with 88% retention after 100 cycles and 165 μAh cm(-2) μm(-1) (1650 mAh cm(-3) or ∼518 mAh g(-1)) obtained at a discharge current density of 1000 μA cm(-2) (∼6.6 C) for 1000 cycles were achieved. Meanwhile an energy density of 294 μWh cm(-2) μm(-1) (2.94 Wh cm(-3) or ∼924 Wh kg(-1)) and power density of 584 μW cm(-2) μm(-1) (5.84 W cm(-3) or ∼1834 W kg(-1)) were also obtained, which may make these thin film anodes promising as a power supply for micro- or even nanosized portable electronic devices.

Tailored Oxygen Framework of Li4Ti5O12 Nanorods for High-Power Li Ion Battery

Here we designed the kinetically favored Li4Ti5O12 by modifying its crystal structure to improve intrinsic Li diffusivity for high power density. Our first-principles calculations revealed that the substituted Na expanded the oxygen framework of Li4Ti5O12 and facilitated Li ion diffusion in Li4Ti5O12 through 3-D high-rate diffusion pathway secured by Na ions. Accordingly, we synthesized sodium-substituted Li4Ti5O12 nanorods having not only a morphological merit from 1-D nanostructure engineering but also sodium substitution-induced open framework to attain ultrafast Li diffusion. The new material exhibited an outstanding cycling stability and capacity retention even at 200 times higher current density (20 C) compared with the initial condition (0.1 C).

CNT@TiO2 nanohybrids for high-performance anode of lithium-ion batteries

This work describes a potential anode material for lithium-ion batteries (LIBs), namely, anatase TiO2 nanoparticle-decorated carbon nanotubes (CNTs@TiO2). The electrochemical properties of CNTs@TiO2 were thoroughly investigated using various electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, and rate experiments. It was revealed that compared with pure TiO2 nanoparticles and CNTs alone, the CNT@TiO2 nanohybrids offered superior rate capability and achieved better cycling performance when used as anodes of LIBs. The CNT@TiO2 nanohybrids exhibited a cycling stability with high reversible capacity of about 190 mAh g-1 after 120 cycles at a current density of 100 mA g-1 and an excellent rate capability (up to 100 mAh g-1 at a current density of 1,000 mA g-1).

Graphene-wrapped MnO2 -graphene nanoribbons as anode materials for high-performance lithium ion batteries

A facile and cost-effective approach for the fabrication of a hierarchical nanocomposite material of graphene-wrapped MnO2 -graphene nanoribbons (GMG) is developed. The resulting composite has a high specific capacity and an excellent cycling stability owing to the synergistic combination of the electrically conductive graphene, graphene nanoribbons, and MnO2 .