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Full-Text Articles in Engineering

High-Performance Sodium-Ion Batteries And Sodium-Ion Pseudocapacitors Based On Mos2/Graphene Composites, Yunxiao Wang, Shulei Chou, David Wexler, Hua-Kun Liu, S X. Dou Oct 2014

High-Performance Sodium-Ion Batteries And Sodium-Ion Pseudocapacitors Based On Mos2/Graphene Composites, Yunxiao Wang, Shulei Chou, David Wexler, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Sodium-ion energy storage, including sodium-ion batteries (NIBs) and electrochemical capacitive storage (NICs), is considered as a promising alternative to lithium-ion energy storage. It is an intriguing prospect, especially for large-scale applications, owing to its low cost and abundance. MoS2 sodiation/desodiation with Na ions is based on the conversion reaction, which is not only able to deliver higher capacity than the intercalation reaction, but can also be applied in capacitive storage owing to its typically sloping charge/discharge curves. Here, NIBs and NICs based on a graphene composite (MoS2/G) were constructed. The enlarged d-spacing, a contribution of the graphene matrix, and the …


Reduced Graphene Oxide With Superior Cycling Stability And Rate Capability For Sodium Storage, Yunxiao Wang, Shulei Chou, Hua-Kun Liu, S X. Dou Mar 2014

Reduced Graphene Oxide With Superior Cycling Stability And Rate Capability For Sodium Storage, Yunxiao Wang, Shulei Chou, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Sodium ion battery is a promising electrical energy storage system for sustainable energy storage applications due to the abundance of sodium resources and their low cost. In this communication, the electrochemical properties of sodium ion storage in reduced graphene oxide (RGO) were studied in an electrolyte consisting of 1 M NaClO4 in propylene carbonate (PC). The experimental results show that the RGO anode allowed significant sodium ion insertion, leading to higher capacity at high current density compared to the previously reported results for carbon materials. This is due to the fact that RGO possesses higher electrical conductivity and is a …


A Facile Route To Synthesize Transition Metal Oxide/Reduced Graphene Oxide Composites And Their Lithium Storage Performance, Chongjun Zhao, Shulei Chou, Yunxiao Wang, Cuifeng Zhou, Hua-Kun Liu, S X. Dou Mar 2014

A Facile Route To Synthesize Transition Metal Oxide/Reduced Graphene Oxide Composites And Their Lithium Storage Performance, Chongjun Zhao, Shulei Chou, Yunxiao Wang, Cuifeng Zhou, Hua-Kun Liu, S X. Dou

Shi Xue Dou

Transition metal oxide (Mn3O4, Fe2O3, Co3O4, and ZnO) and reduced graphene oxide (RGO) composites were successfully synthesized via a hydrothermal method using the direct reaction between the corresponding metal powder and graphene oxide (GO). In this process, the GO can be reduced by transition metal powder in water, and the nanosized metal oxide can be obtained, and homogeneously mixed with and wrapped by RGO to form a metal oxide/RGO composite at the same time. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning and transmission electron microscopy were used to characterize the as-prepared materials. The different experimental parameters, including reactants, …


Fusion Of Nacre, Mussel, And Lotus Leaf: Bio-Inspired Graphene Composite Paper With Multifunctional Integration, Da Zhong, Qinglin Yang, Lin Guo, S X. Dou, Kesong Liu, Lei Jiang Mar 2014

Fusion Of Nacre, Mussel, And Lotus Leaf: Bio-Inspired Graphene Composite Paper With Multifunctional Integration, Da Zhong, Qinglin Yang, Lin Guo, S X. Dou, Kesong Liu, Lei Jiang

Shi Xue Dou

Multifunctional integration is an inherent characteristic for biological materials with multiscale structures. Learning from nature is an effective approach for scientists and engineers to construct multifunctional materials. In nature, mollusks (abalone), mussels, and the lotus have evolved different and optimized solutions to survive. Here, bio-inspired multifunctional graphene composite paper was fabricated in situ through the fusion of the different biological solutions from nacre (brick-and-mortar structure), mussel adhesive protein (adhesive property and reducing character), and the lotus leaf (self-cleaning effect). Owing to the special properties (self-polymerization, reduction, and adhesion), dopamine could be simultaneously used as a reducing agent for graphene oxide …


The Electrochemical Properties Of High-Capacity Sulfur/Reduced Graphene Oxide With Different Electrolyte Systems, Yunxiao Wang, Shulei Chou, Hua-Kun Liu, S X. Dou Mar 2014

The Electrochemical Properties Of High-Capacity Sulfur/Reduced Graphene Oxide With Different Electrolyte Systems, Yunxiao Wang, Shulei Chou, Hua-Kun Liu, S X. Dou

Shi Xue Dou

The lithium/sulfur battery is a promising electrochemical system with high capacity, which is well-known to undergo a complex multistep reaction during the discharge process. Two types of electrolytes including poly (ethylene glycol) dimethyl ether (PEGDME)-based and 1.3 - dioxolane (DOL)/ dimethoxyethane (DME)-based electrolytes were investigated here. Furthermore, LiNO3 additive was introduced into the electrolyte in order to effectively eliminate the overcharge effect. The lithium sulfur battery with 1.0 M LiN(CF3SO2)2 in PEGME with 0.1 M LiNo3 shows highly stable reversible capacity of 624.8 mAh g-1 after 200 cycles and improved average coulombic efficiency of 98 percent.


A Significant Improvement In The Superconducting Properties Of Mgb2 By Co-Doping With Graphene And Nano-Sic, K S B De Silva, X Xu, Xiaolin Wang, D Wexler, D Attard, F Xiang, S. X. Dou Jun 2013

A Significant Improvement In The Superconducting Properties Of Mgb2 By Co-Doping With Graphene And Nano-Sic, K S B De Silva, X Xu, Xiaolin Wang, D Wexler, D Attard, F Xiang, S. X. Dou

Shi Xue Dou

The effects of graphene (G) and nanosilicon carbide (SiC) co-doping on the superconducting properties of MgB2 were studied using bulk samples. SiC remains one of the best dopants which can significantly improve the high field performance, while graphene is emerging as a new dopant for MgB2, which can improve the zero field critical current density (Jc). The superconducting properties characterized by Jc, the intergrain connectivity, and the critical fields were significantly improved by the use of both SiC and graphene as dopants.


The Effect Of Reduced Graphene Oxide Addition On The Superconductivity Of Mgb2, K S. B De Silva, S Gambhir, Xiaolin Wang, X Xu, W X. Li, David L. Officer, D Wexler, G G. Wallace, S. X. Dou Jun 2013

The Effect Of Reduced Graphene Oxide Addition On The Superconductivity Of Mgb2, K S. B De Silva, S Gambhir, Xiaolin Wang, X Xu, W X. Li, David L. Officer, D Wexler, G G. Wallace, S. X. Dou

Shi Xue Dou

Reduced graphene oxide (rGO) and highly reduced chemically converted graphene (ICCO) samples were prepared under different processing condition! and were doped into MgBz by a diffusion process at 800 °C for 10 houn. It was demonstrated that a small addition rCCG can significantly improve the supcn;onducting properties of MgBz. Doping of M8B2 with 1 mol% of rCCG resulted in a Ie of 5.45 X lOS A cm-2 at 20 K in self-fields, which il nearly 32% improvement over that of the undopcd sample. This is a significant improvement as most carbon sources adversely affect the Ie performance: at the zero …


Graphene Micro-Substrate Induced High Electron-Phonon Coupling In Mgb2, W X. Li, X Xu, K S. B De Silva, F X. Xiang, S X. Dou Jun 2013

Graphene Micro-Substrate Induced High Electron-Phonon Coupling In Mgb2, W X. Li, X Xu, K S. B De Silva, F X. Xiang, S X. Dou

Shi Xue Dou

Electron-phonon coupling strength was studied in graphene-MgB2 composites to explore the possibilities for a higher superconducting transition temperature (Tc). For the first time in the experimental work on MgB2, the Raman active E2g mode was split into two parts: a softened mode corresponding to tensile strain and a hardened mode attributed to the carbon substitution effect. The tensile strain effect is suggested to improve Tc of graphene-MgB2 composites because it increases the electron-phonon coupling strength of MgB2.


Superconducting Properties Of Graphene Doped Magnesium Diboride, Xun Xu, Wenxian Li, Xiaolin Wang, S. X. Dou Jun 2013

Superconducting Properties Of Graphene Doped Magnesium Diboride, Xun Xu, Wenxian Li, Xiaolin Wang, S. X. Dou

Shi Xue Dou

Graphene, carbon in the form of monolayer sheets, has revealed astonishing and unique chemical and physical properties, which have made it an extremely active research topic in both materials science and physics (Novoselov, K. S. et al., 2004). Through chemical and materials integration, graphene is being actively exploited in a range of technological applications (Stankovich, S. et al., 2006). Superconductors can carry electrical current without any energy dissipation. The combination of both graphene and a superconductor into a composite has great potential for electrical devices and large scale applications. MgB2, a superconductor with a simple composition and two-gap feature has …


Dependence Of Magnetoelectric Properties On Sintering Temperature For Nano-Sic-Doped Mgb2/Fe Wires Made By Combined In Situ/Ex Situ Process, Wenxian Li, Rong Zeng, Jiazhao Wang, Y Li, S. X. Dou Jun 2013

Dependence Of Magnetoelectric Properties On Sintering Temperature For Nano-Sic-Doped Mgb2/Fe Wires Made By Combined In Situ/Ex Situ Process, Wenxian Li, Rong Zeng, Jiazhao Wang, Y Li, S. X. Dou

Shi Xue Dou

Very fine nano-SiC particles (nm) were doped into a MgB2 superconductor. The influence of self-field supercurrent on the high-field performance of the nano-SiC-doped MgB2/Fe wires is discussed based on comparison of the critical current densities of the in situ processed nano-SiCdoped MgB2 wires and those of the nano-SiC-doped MgB2/Fe wires processed by the combination of in situ/ex situ methods.