Electrochemical Performance Of Composite Material Research Articles

Enhancing Electrochemical Performance of Co(OH)2 Anode Materials by Introducing Graphene for Next-Generation Li-ion Batteries

To satisfy the growing demand for high-performance batteries, diverse novel anode materials with high specific capacities have been developed to replace commercial graphite. Among them, cobalt hydroxides have received considerable attention as promising anode materials for lithium-ion batteries as they exhibit a high reversible capacity owing to the additional reaction of LiOH, followed by conversion reaction. In this study, we introduced graphene in the fabrication of Co(OH)2-based anode materials to further improve electrochemical performance. The resultant Co(OH)2/graphene composite exhibited a larger reversible capacity of ~1090 mAh g−1, compared with ~705 mAh g−1 for bare Co(OH)2. Synchrotron-based analyses were conducted to explore the beneficial effects of graphene on the composite material. The experimental results demonstrate that introducing graphene into Co(OH)2 facilitates both the conversion and reaction of the LiOH phase and provides additional lithium storage sites. In addition to insights into how the electrochemical performance of composite materials can be improved, this study also provides an effective strategy for designing composite materials.

Oxidized Multiwalled Carbon Nanotubes as Components and Oxidant Agents in the Formation of Multiwalled Carbon Nanotube/Polyazulene Composites

This work describes the practical and facile synthesis of oxidized multiwalled carbon nanotube/polyazulene (ox-MWCNT/PAZ) composites. In the proposed procedure, oxidized multiwalled carbon nanotubes were used both as components and oxidant agents in the formed composite material, which eliminated the use of conventional oxidizing agents such as ferric chloride. The properties and morphology of composite materials depend on the synthesis conditions, such as monomer concentration, synthesis time and synthesis temperature. The composite material is much more stable at high temperatures than pristine polyazulene. Additionally, the electrochemical performance of composite materials is better than that of pure polymeric materials. The highest specific capacitance of the ox-MWCNT/PAZ composite equals 381 F gPAZ −1. This value is approximately 5 times higher than the specific capacitance of pristine polyazulene. This high value results from the larger surface area of the composite material and its easier penetration by counterions of the supporting electrolyte during the oxidation process. Apart from the traditional doping process by counterions, the composite material is additionally codoped by hexafluorophosphate anions of the supporting electrolyte, which form hydrogen bonds with surface hydroxyl groups of ox-MWCNTs.

Design of Nb2O5@rGO composites to optimize the lithium-ion storage performance

Compounding with carbonaceous materials is the most common method used to improve the performance of battery electrodes. In this work, the hydrothermal method is employed to synthesize the pure Nb2O5 and Nb2O5@rGO composites. Meanwhile, the electrochemical performance of pure Nb2O5 and Nb2O5@rGO composites as the anode for the lithium-ion battery is studied. The pure Nb2O5 exhibits the cycling stability keeping 58% of the initial specific capacity after 1000 cycles at the current density of 1.0 A g−1 and the specific capacity of 120 mAh g−1 at the current density of 1.0 A g−1, but the Nb2O5@rGO composites all show the cycling stability keeping 100% of the initial specific capacity after 1000 cycles at the current density of 1.0 A g−1 and higher specific capacity than that of the pure Nb2O5. When the amount of rGO in the Nb2O5@rGO composite is the largest, the specific capacity of Nb2O5@rGO composite is maximum (270 mAh g−1 at the current density of 1.0 A g−1). In addition, after introduction of rGO, the conductivity and rate performance of composite materials can also be improved. This work well proves that compounding with the rGO can improve the electrochemical performance of composite material.

Study on Efficient Electrode from Electronic waste renewed carbon material for sodium battery applications

The present work enlightens the preparation of anode material for sodium battery by utilizing the powder from exhausted printer cartridges (pEPC). Herein, the toner powder was heat treated to obtain carbon-ferric (C/Fe3O4) composite. The obtained composite’s structure, surface morphology were analyzed using X-ray diffraction, and electron microscopic analyses. The electrochemical performance of composite material was examined by using this material as anode for sodium ion battery. The composite material delivered an initial discharge capacity of 410 m Ah g−1 in the range 0.1–3.0 V with 93% coulombic efficiency; Even after 100 cycles, the material delivered 280 m Ah g−1. This work proposes the potentiality of recycling the waste toner as anode materials for sodium ion batteries. By this way, the environmental issues can be minimized from the hazardous e-waste and renewed it for energy storage application.

Porous silicon–graphene–carbon composite as high performance anode material for lithium ion batteries

Abstract The porous silicon-graphene-carbon (SGC) composite is prepared by freeze-drying and chemical vapor deposition (CVD) process with commercially available nano-silicon, phenolic resin and graphene oxide as raw materials. The self-assembly process makes the nano-silicon into a porous structure and uniform recombination with the graphene oxide, and finally a nano-carbon layer is coated on the surface of the SGC composite by a CVD process. The composition, morphology and pore properties of SGC composite are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and pore size analysis. The nano-carbon layer on the surface of the SGC is examined by transmission electron microscopy (TEM) and Raman spectrometer. The contents of C, Si and O in precursor and SGC are analyzed by X-Ray Fluorescence (XRF), and the electrochemical performances of composite material are analyzed by half-cell and full-cell experiments. The results show that the SGC composite is porous structure with the average pore size of 20–30 nm, and the surface of the porous silicon-graphene is coated by a thickness of 5 nm carbon layers. The reversible capacity and initial coulombic efficiency (ICE) of the SGC are 2180 mAh g−1 and 79.3%. The capacity retention is higher than 70.1% after 100 charge/discharge cycles by the half-cell experiment; and the capacity of the composite anode is still as high as 550 m Ah g−1 after 820 charge/discharge cycles by full-cell experiment. Therefore, the structure design strategy of the composite is beneficial to buffer the volume effect of nano-silicon, prevent iterative growth of the SEI film and boost the electrochemical performances.

FeS/ZnS nanoflower composites as high performance anode materials for sodium ion batteries

The electrochemical performance of composite materials can be effectively improved by regulating multiple components and designing well-defined microstructure. In this work, FeS/ZnS composites with different Fe/Zn ratios were prepared through a facile wet chemical method. The as-prepared sulfide composite with molar ratio Fe/Zn = 1 exhibits optimal nanoflower morphology and achieves a high specific capacity as sodium-ion battery anode with reversible capacity of 475.1 mA h g−1 after 50 cycles at a current density of 100 mA g−1. Moreover, even at a high current density of 2000 mA g−1, a stable capacity of 207.6 mA h g−1 can be obtained. The superior electrochemical performance can be attributed to the design of optimal nanoflower structure through the regulation of Fe/Zn ratio, and the nanostructure can efficiently buffer volume change during discharge-charge, shorten Na+ diffusion pathways, promote the electrode/electrolyte contact, and thus render the sulfide composite FeS/ZnS a promising anode material for advanced sodium-ion batteries.

The graphene/lanthanum oxide nanocomposites as electrode materials of supercapacitors

In this paper, the nanocomposites of reduced graphene oxide/lanthanum oxide are prepared by a simple reflux process. The reduced graphene oxide with a large specific surface area is successfully decorated with lanthanum oxide. The reduced graphene oxide/lanthanum oxide composites are fabricated as the electrode material in a supercapacitor device which displays a high specific capacitance of 156.25 F/g at a current density of 0.1 A/g and excellent cycle stability. The material keeps 78% of its initial charge-discharge efficiency after 500 cycles. The excellent electrochemical performance of composite material may be attributed to the deposited lanthanum oxide nanoparticle on the surface of reduced graphene oxide, which increase the effective conductive area of reduced graphene oxide and the contact area between electrolyte and graphene. The graphene-lanthanum oxide composites can significantly improve the stability and electrical performance of supercapacitors and has great potential in chemical sensors, microelectronics, energy storage and conversion applications.

High rate capability and cyclic stability of hierarchically porous Tin oxide (IV)\u2013carbon nanofibers as anode in lithium ion batteries

Tin oxide–carbon composite porous nanofibres exhibiting superior electrochemical performance as lithium ion battery (LIB) anode have been prepared using electrospinning technique. Surface morphology and structural characterizations of the composite material is carried out by techniques such as XRD, FESEM, HR-TEM, XPS, TGA and Raman spectroscopy. FESEM and TEM studies reveal that nanofibers have a uniform diameter of 150–180 nm and contain highly porous outer wall. The carbon content is limited to ~10% in the nanofibers as shown by the TGA and EDAX which does not fade the high capacity of SnO2. These nanofibers delivered a higher discharge capacity of 722 mAh/g even after 100 cycles at high rate of 1C. The excellent electrochemical performance can be ascribed to the synergy effect of small amount of carbon in the composite and the hierarchically porous structure which accommodate large volume changes associated with Li-ion insertion–desertion. The porous nano-architecture would also provide a short diffusion path for Li+ ions in addition to facilitating high flux of electrolyte percolation through micropores. The electrochemical performance of composite material has also been tested at 60 °C at a higher rate of 2C and 5C. Post cycling FESEM analysis shows no volumetric and morphology changes in porous nanofibers after completing rate capability at high rate of 10C.

Study on Preparation of Si/C Anode Material by Spray Dying and Carbonization

Si/C composites were prepared by spray dying and carbonization process using silica powder, artificial graphite and glucose as raw materials. The physicochemical property and electrochemical performance of composite materials were characterized by XRD, SEM, constant current charge-discharge and cyclic voltammeter (CA) test, respectively. The results show that composite anode materials have pure phase structure with particle size of 5~20μm, and its special structure that silicon and graphite particles are constructed can exhibit good electrochemical performance. The initial discharge specific capacity of Si/C composites is 1033.2mAhg-1 at a current density of 100mAg-1.While the current density is as high as 600mAg-1, the discharge specific capacity is 584.2mAhg-1, and the first cycle coulombic efficiency is 77.3% at 100mAg-1.The mechanism of capacity fading of Si/C composites is discussed by different morphology characterization after 100 cycles.