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Zhao Y.,Hebei University of Technology | Bakenova Z.,Institute of Batteries LLC | Zhang Y.,Hebei University of Technology | Peng H.,Hebei University of Technology | And 3 more authors.
Ionics | Year: 2015

A sulfur/nitrogen-doped graphene (S/N-G) composite was synthesized by simple sonicated mixing of nanosized sulfur suspension and nitrogen-doped graphene suspension followed by heat treatment. Scanning electron microscopy and energy dispersive spectroscopy mapping showed the formation of a porous structure with uniform distribution of sulfur and nitrogen-doped graphene. Electrochemical performance reveals that the resultant S/N-G composite exhibits a high reversible capacity of 1355 mAh g−1 at the initial cycle, with 823 mAh g−1 remaining after 80 cycles at 0.1 C. Moreover, a reversible capacity of 475 mAh g−1 could still be obtained at 2.5 C. Such an electrochemical performance of S/N-G composite is superior to the graphene counterpart. The enhanced electrochemical performance can be attributed to the introduction of nitrogen-doped graphene with the N functionalization, which provides both a more effective electron conduction path and a stronger physical and chemical confinement setting for elemental sulfur and resident polysulfides. © 2015, Springer-Verlag Berlin Heidelberg. Source


Yermukhambetova A.,Nazarbayev University | Bakenov Z.,Nazarbayev University | Bakenov Z.,Institute of Batteries LLC | Zhang Y.,Institute of Batteries LLC | And 4 more authors.
Journal of Electroanalytical Chemistry | Year: 2015

Nanostructured magnesium nickel oxide Mg0.6Ni0.4O and alumina Al2O3 were studied as additives to sulphur/polyaniline (S/PANI) composites via wet ball-milling of sulphur and polyaniline followed by heat treatment. Metal oxide nanoparticles, which have small particle size, porous structure and high specific surface area to volume ratio, are expected to be catalytic for chemical reactions, including electron transfer and are able to adsorb lithium polysulphides. The composites were characterized by SEM and electrochemical methods. Cyclic voltammetry studies suggest that the alumina additive acts differently to the Mg0.6Ni0.4O. The results suggest that although the alumina additive improves the S/PANI composite performance as a lithium-sulphur battery cathode, the use of Mg0.6Ni0.4O is more effective. © 2015. Source


Yesibolati N.,Nazarbayev University | Yesibolati N.,Institute of Batteries LLC | Umirov N.,Nazarbayev University | Umirov N.,Institute of Batteries LLC | And 12 more authors.
Electrochimica Acta | Year: 2015

In this work, a novel aqueous rechargeable battery Zn/LiCl-ZnCl2/LiFePO4 has been developed. The electrochemical performance of olivine LiFePO4 positive electrode has been investigated in the structure of this battery. Along with a high (about 100%) coulombic efficiency, this electrode exhibited enhanced cycling performance at various current densities up to 60 C with the average operation voltage 1.2 V. A capacity of 92 mAh g-1 was achieved over 400 cycles at a cycling rate 6 C, and exhibited a superior rate capability with the capacities of 72 mAh g-1 at 30 C and 45 mAh g-1 at 60 C, respectively. The battery temperature tolerance was first investigated, and it demonstrated a very stable cycling at a wide temperature range from -10 °C to 50 °C. A cylindrical battery with the capacity of 150 mAh was first designed using proposed configuration and successfully operated under 54 mA with high efficiency and capacity retention. Zn/LiFePO4 battery offers an exceptionally safe, low cost, long cycling life, and high energy and power density energy storage for large-scale applications. © 2014 Elsevier Ltd. All rights reserved. Source


Zhang Y.,Nazarbayev University | Zhang Y.,Institute of Batteries LLC | Zhao Y.,Nazarbayev University | Zhao Y.,Institute of Batteries LLC | And 2 more authors.
Ionics | Year: 2014

We report on a simple and facile synthesis route for the sulfur/graphene oxide composite via ultrasonic mixing of the nano-sulfur and graphene oxide aqueous suspensions followed by a low-temperature heat treatment. High-resolution transmission and scanning electronic microscopy observations revealed the formation of a highly porous structure consisting of sulfur with uniform graphene oxide coating on its surface. The resulting sulfur/graphene oxide (S/GO) composite exhibited high and stable specific discharge capacities of 591 mAh g-1 after 100 cycles at 0.1 C and good rate capability. This enhanced electrochemical performance could be attributed to the effective confining the polysulfides dissolution and accommodation of the volume changes during the Li-S electrochemical reaction by the functional groups on the graphene oxide coating layer. Furthermore, the highly developed porous structure of S/GO composite favors the enhanced ion transport and electrolyte diffusion. © 2014 Springer-Verlag Berlin Heidelberg. Source


Zhao Y.,Hebei University of Technology | Yin F.,Hebei University of Technology | Zhang Y.,Hebei University of Technology | Zhang C.,Hebei University of Technology | And 7 more authors.
Nanoscale Research Letters | Year: 2015

A free-standing sulfur/nitrogen-doped carbon nanotube (S/N-CNT) composite prepared via a simple solution method was first studied as a cathode material for lithium/sulfur batteries. By taking advantage of the self-weaving behavior of N-CNT, binders and current collectors are rendered unnecessary in the cathode, thereby simplifying its manufacturing and increasing the sulfur weight ratio in the electrode. Transmission electronic microscopy showed the formation of a highly developed core-shell tubular structure consisting of S/N-CNT composite with uniform sulfur coating on the surface of N-CNT. As a core in the composite, the N-CNT with N functionalization provides a highly conductive and mechanically flexible framework, enhancing the electronic conductivity and consequently the rate capability of the material. © 2015, Zhao et al. Source

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