Porous structured SnSb/C nanocomposites for Li-ion battery anodes

Here, we report a simple, cheap, and rapid synthesis method combined with physical and chemical routes for porous structured metal-based carbon nanocomposites, which can be applicable to anode materials for high performance Li-ion batteries.     

Multilayered structure of N-carbonenvelopediron oxide/graphene nanocomposites as an improved anode for Li-ion battery

Transition metal oxides with high capacity are considered a promising electrode material for lithium-ion batteries (LIBs). Nevertheless, the huge volume expansion and poor conductivity severely hamper their practical application. In this work, a carbon riveting method is reported to address the above issues by designing multilayered N-doped carbon (N-carbon) enveloped Fe₃O₄/graphene nanosheets. When evaluated as a negative electrode, the N-carbon/Fe₃O₄/graphene nanocomposites demonstrate greatly enhanced electrochemical properties compared with Fe₃O₄/graphene. The N-carbon/Fe₃O₄/graphene presents a superior reversible capacity (807 mAh/g) over Fe₃O₄/graphene (540 mAh/g). Furthermore, it affords a considerable capacity of 550 mAh/g at 1 A/g over 700 cycles, indicating superb cycling stability. The structure-property correlation studies reveal that the carbon riveting layer is essential for enhancing the lithium diffusion kinetics. The good electrochemical properties and effective structure design make the carbon riveting strategy quite general and reliable to manipulate high performance electrodes for future LIBs.     

GBL-based electrolyte for Li-ion battery: thermal and electrochemical performance

Thermal stability, flammability, and electrochemical performances of the cyclic carbonate-based electrolytes [where γ-butyrolactone (GBL) is a main component (at least 50 vol.%) among of EC and PC with LiBF₄] have been examined in comparison with contemporary (EC/EMC, 1:3 vol.%, 1 M LiPF₆) electrolyte by DSC, accelerating rate calorimetry (ARC), AC impedance, and cyclic voltammetry (CV). This study shows that GBL-based electrolytes have perfect thermal stability and will improve Li-ion battery safety (including flammability) without performance trade-off with the accurate combination of active materials and separator. Several types of negative electrode materials (such as hard carbon, MCMB, and SWF) have been tested to evaluate GBL-based electrolyte influence on SEI formation and battery performance. Finally, GBL-based electrolytes show not only equal electrochemical performance in comparison to commonly used electrolytes (EC/EMC in this study) but it will notably improve battery safety.     

Hierarchical micro/nano porous silicon Li-ion battery anodes

A wet-chemical etching method is reported for the scale-up preparation of carbon-coated hierarchical micro/nano porous silicon powders as a Li-ion battery anode, which shows no capacity fading at 1500 mA h g(-1) in 50 charge/discharge cycles.     

Preparation and electrochemical performance for methanol oxidation of pt/graphene nanocomposites

The composites of graphene nanosheets decorated by Pt nano clusters have been prepared via reduction of graphite oxide and H₂PtCl₆ in one pot. Electrochemical experiments show that the composites have superior catalytic performance toward methanol oxidation indicating the graphene may have a splendid future as catalysts carrier in electrocatalysis and fuel cell.     

Preparation of MnO2 and MnO2/carbon nanotubes nanocomposites with improved electrochemical performance for lithium ion batteries

Journal of Solid State Electrochemistry - Manganese dioxide (MnO2) nanomaterials and manganese dioxide/carbon nanotubes (MnO2/CNTs) nanocomposites were prepared by chemical precipitation and...     

碳网封装Fe3O4/还原氧化石墨烯锂离子电池负极材料

通过简单有效的溶剂热法将Fe3 O4颗粒与氧化石墨烯(GO)进行复合,得到Fe3 O4/GO复合材料.将Fe3 O4/GO与葡萄糖进行碾磨.在高温下将GO还原成还原氧化石墨烯(rGO)的同时在Fe3 O4/rGO表面制备网状结构的导电碳层,得到三维网络传输结构C/Fe3 O4/rGO复合材料.由碳网和还原氧化石墨烯组成...     

碳包覆磷酸亚铁锂/石墨烯复合结构的制备及其电化学性能

通过简单的水热和气相沉积法合成了碳包覆磷酸亚铁锂/石墨烯复合材料,通过XRD,SEM,TEM等对其形貌进行了表征,并将其用作锂离子电池正极材料进行电化学性能表征,结果表明:碳包覆磷酸亚铁锂/石墨烯复合材料即使在10C的倍率下仍有115mAh·g~(-1)的容量,同时在10C循环300次,容量保持率为82%.其优异的倍率和循环性能归因于沉积碳、石墨烯以及磷酸亚铁锂之间层层叠加的独特三维导电结构.     

Enhanced rate performance and cyclic stability of Fe3O4-graphene nanocomposites for Li ion battery anodes

Monodispersed Fe(3)O(4) nanoparticles of size ～10 nm were processed by a simple ultrasonic assisted co-precipitation method, mechanically mixed with graphene oxide, and thermally reduced to form a magnetite-graphene composite. Electrochemical characterization of the Fe(3)O(4)-graphene nanocomposites showed excellent capacity in excess of 1200 mA h g(-1), and exceptional stability during high current cycling for at least 1000 cycles.     

TiO2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance

TiO_2 nanocrystals/graphene hybrids(TiO_2-G) with ultrafine TiO_2 nanocrystals(~7 nm in size) conformally coated on ultrathin graphene nanosheets(~ 2 layers thick) were successfully prepared via a facile one-pot solvothermal route under mediated conditions.With the feature of large surface area,abundant mesopores and high thermal stability,the TiOi-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability(629 mAh·g~(-1) after 400 cycles at a current of 60 mA·g~(-1)) and good rate capability(184 mAh·g~(-1) at a current density of 3 A·g~(-1)) due to the synergetic effects and strong interactions between the components,showing great promise in applications for advanced energy storage devices.     

TiO_2 nanocrystals/graphene hybrids with enhanced Li-ion storage performance

TiO_2 nanocrystals/graphene hybrids(TiO_2-G) with ultrafine TiO_2 nanocrystals(~7 nm in size) conformally coated on ultrathin graphene nanosheets(~ 2 layers thick) were successfully prepared via a facile one-pot solvothermal route under mediated conditions.With the feature of large surface area,abundant mesopores and high thermal stability,the TiOi-G nanohybrids exhibited large reversible Li-ion storage capacity with excellent cycling stability(629 mAh·g~(-1) after 400 cycles at a current of 60 mA·g~(-1)) and good rate capability(184 mAh·g~(-1) at a current density of 3 A·g~(-1)) due to the synergetic effects and strong interactions between the components,showing great promise in applications for advanced energy storage devices.     

One-pot synthesis of Fe3O4/polypyrrole/graphene oxide nanocomposites for electrochemical sensing of hydrazine

Microchimica Acta - The authors describe the synthesis of a nanocomposite consisting of Fe3O4 nanoparticles, polypyrrole and graphene oxide (Fe3O4/PPy/GO), and its application to voltammetric...     

The design and fabrication of Co_3O_4/Co_3V_2O_8/Ni nanocomposites as high-performance anodes for Li-ion batteries

The Co_3O_4/Co_3V_2O_8/Ni nanocomposites were rationally designed and prepared by a two-step hydrothermal synthesis and subsequent annealing treatment. The one-dimensional(1D) Co_3O_4 nanowire arrays directly grew on Ni foam, whereas the 1D Co_3V_2O_8 nanowires adhered to parts of Co_3O_4 nanowires.Most of the hybrid nanowires were inlayed with each other, forming a 3D hybrid nanowires network.As a result, the discharge capacity of Co_3O_4/Co_3V_2O_8/Ni nanocomposites could reach 1201.8 mAh/g after100 cycles at 100 mA/g. After 600 cycles at 1 A/g, the discharge capacity was maintained at 828.1 mAh/g.Moreover, even though the charge/discharge rates were increased to 10 A/g, it rendered reversible capacity of 491.2 mAh/g. The superior electrochemical properties of nanocomposites were probably ascribed to their unique 3D architecture and the synergistic effects of two active materials. Therefore, such Co_3O_4/Co_3V_2O_8/Ni nanocomposites could potentially be used as anode materials for high-performance Li-ion batteries.     

Stacked graphene nanofibers doped polypyrrole nanocomposites for electrochemical sensing

This publication shows a single-step electropolymerization which has been carried out by the incorporation of an anionic stacked graphene nanofiber (SGNF) dopant into a polypyrrole (PPy) film, at a disposable screen-printed electrode. The incorporation of the SGNFs into the polymer does not affect their electrochemical properties, shown through cyclic voltammetry by the earlier oxidation of guanine, when compared with that at the graphite doped PPy electrode. The SGNF/PPy composite shows a high selectivity when used in the oxidation of guanine and hydrogen peroxide, both of which are important biomarkers used for biosensing. Disposable screen-printed electrodes provide an inexpensive, sensitive and portable substitute to glassy carbon electrodes, while giving a reproducible surface; qualities essential for effective bionsensing. The production of this single-step disposable SGNF/PPy composite electrode allows for further applications in the detection of biomedically important compounds and DNA sensing.     

Synthesis of carbon-coated Li4Ti5O12 and its electrochemical performance as anode material for lithium-ion battery

Carbon-coated Li_4Ti_5O_(12) sample was synthesized by a sol-gel method. The Li_4Ti_5O_(12) powders were obtained by calcinations of the gels at 750, 800, 850,900 ℃ at N_2 atmosphere. The structure, morphology and electrochemical properties of the materials were characterized by SEM, XRD and charge and discharge. The final product sintered at 850 ℃ demonstrates excellent performance with a specific capacity of 163.5 mAh/g after 100 cycles at 1C. Furthermore, the discharge specific capacity of the sample can retain 80 mAh/g at 10C.     

Optimizing carbon coating parameters for obtaining SiO2/C anodes with improved electrochemical performance

In this work, we present a comprehensive and systematic study on the use of low-cost and highly abundant carbon precursors to obtain SiO₂/C anodes with superior electrochemical performance towards Li-ions. Different SiO₂/C composites are prepared by soaking silica nanoparticles in solutions containing 20 wt%, 40 wt%, or 60 wt% of glucose, sucrose, or cornstarch, followed by thermal decomposition of the carbohydrates at 850 °C or 1200 °C. Structural, microstructural, and textural differences on the composites derived from the different carbon coating treatments are related to the electrochemical performance of the anodes. Composites containing final carbon contents close to 15 wt% show a complete coverage of the SiO₂ particles with a nanometric carbon layer and exhibit the best electrochemical results. The increase in the annealing temperature from 850 to 1200 °C reduces the porosity of the carbon layer and increases its level of ordering, both having positive effects on the overall electrochemical performance of the electrodes. SiO₂/C composites coated with 40 wt% sucrose and heat treated at 1200 °C display the best electrochemical performance, delivering a reversible specific capacity of 723 mAhg⁻¹ at 50 mAg⁻¹ after 100 cycles, which is considerably higher than the reversible capacity of 233 mAhg⁻¹ obtained with the uncoated material cycled under the same conditions.

     

Effect of fluoroethylene carbonate (FEC) on the performance and surface chemistry of Si-nanowire Li-ion battery anodes

The effect of FEC as a co-solvent on the electrochemical performance and surface chemistry of silicon nanowire (SiNW) anodes was thoroughly investigated. Enhanced electrochemical performance was observed for SiNW anodes in alkyl carbonates electrolyte solutions containing fluoroethylene carbonate (FEC). Reduced irreversible capacity losses accompanied by enhanced and stable reversible capacities over prolonged cycling were achieved with FEC-containing electrolyte solutions. TEM studies provided evidence for the complete and incomplete lithiation of SiNW's in FEC-containing and FEC-free electrolyte solutions, respectively. Scanning electron microscopy (SEM) results proved the formation of much thinner and compact surface films on SiNW's in FEC-containing solutions. However, thicker surface films were identified for SiNW electrodes cycled in FEC-free solutions. SiNW electrodes develop lower impedance in electrolyte solutions containing FEC in contrast to standard (FEC-free) solutions. The surface chemistry of SiNW electrodes cycled in FEC-modified and standard electrolytes were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The impact of FEC as a co-solvent on the electrochemical behavior of SiNW electrodes is discussed herein in light of the spectroscopic and microscopic studies.     

Template free electrochemical deposition of ZnSb nanotubes for Li ion battery anodes

ZnSb nanotubes were grown through a template free electrodeposition method under over-potential conditions. The growth of the nanotubes was attributed to the template effect from H(2) bubbles. Due to their hollow structure, the ZnSb nanotubes depicted better Li ion storage performance compared to that of ZnSb nanoparticles deposited under different conditions.