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Phone: þ82 55 772 1668, Fax: þ82 55 772 1670During discharge of lithium sulfur (Li-S) battery with a liquid electrolyte system, sulfur is first reduced to Li 2 S 8 , which is dissolved into the organic electrolyte and this serves as the liquid cathode. In solution, lithium polysulfides undergo a series of chemical reactions and their concentration varies during cell reaction. The amount of sulfur and electrolytes in the system plays an important role in determining the cell performance. In this work, the effect of sulfur loading in cathode and the amount of electrolyte on the energy density and cycle performance of Li-S battery has been investigated. Cathodes with sulfur loading of 0.99, 2.98, and 6.80 mg_S cm À2 were prepared. Precisely controlled amount of electrolyte was added with varied electrolyte/sulfur (E/S) ratios of 1.67, 5, 10, 20, and 40 ml/mg_S. The surface morphology of fresh and cycled sulfur cathodes was characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).

The surface decoration of CoS2 on SPAN–CNT nanofibers endows lithium–sulfur (Li–S) batteries with outstanding capacity reversibility and high energy density.

Organic cathode materials are of great interest for application in batteries due to their abundant availability and environmental compatibility. An approach to make long chain molecules of these organic materials in order to overcome the problem of dissolution in a liquid electrolyte (LE) and incorporate a highly conducting material to enhance the poor electric conductivity of these materials would be of great research interest. In this work, a novel polyimide (PI)/multiwalled carbon nanotube (MWCNT) nanocomposite is prepared as the cathode material for organic Na-ion batteries (NIBs), via a two-step imidization reaction using perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and diaminopropane (DAP) to form an insoluble PI. The MWCNT in the composite serves as the conductive channel to maximize the utilization of the active material in the electrode. Furthermore, a three-dimensional fiber network is prepared from an electrospun polyacrylonitrile nanofibrous membrane and used as a gel polymer electrolyte (GPE) with efficient electrolyte uptake and high ionic conductivity. The combination of the PI/MWCNT nanocomposite cathode and GPE results in a highly efficient organic NIB with an ultralong life span of 3000 cycles and stable cycle performance at high C-rates.

Simple and scalable synthesis of binder free CuS anode with ultrafast, high capacity and long-cycling.

Concrete is certainly prone to internal deteriorations or defects during the construction and operating periods. Compared with other nondestructive techniques, infrared thermography can easily detect the subsurface delamination in a very short period of time, but accurately identifying its size and depth in concrete is a very challenging task. In this study, experimental testing was carried out on a concrete specimen having internal delaminations of various sizes and at varying depths. Delaminations at 1 and 2 cm deep showed a good temperature contrast after only 5-minute heating, but delaminations at 3 cm practically identified the value of the temperature contrast from heating of 15 minutes. In addition, the size of the delamination at 3 cm deep could be estimated with a difference of 10% to 28% for 20 minutes of heating. The depth of the delamination was linearly correlated with the increase in its size.

A highly ordered mesoporous sulfurized polyacrylonitrile (MSPAN) composite has been synthesized via in situ polymerization of polyacrylonitrile (PAN) in an SBA-15 template followed by sulfurization. The synthesized composite possessed high sulfur utilization, high Coulombic efficiency, and excellent cycling stability as a cathode active material for high-rate lithium sulfur (Li−S) batteries. A highly ordered mesoporous structure was observed in the MSPAN composite from transmission electron microscopy. Excellent electrochemical and stable cycling performances of the MSPAN composite were obtained, especially at high C rates. The capacity retention of the MSPAN cell was 755 mAh g −1 after 200 cycles at 1 C and 610 mAh g −1 after 900 cycles at 2 C. Even at a higher rate of 5 C, the composite showed reasonable capacity retention. The superior performance of the MSPAN composite was attributed to its highly porous structure, which could effectively improve the wettability, accessibility, and absorption of electrolyte, facilitating rapid ion transfer in Li−S batteries. The electrochemical results demonstrate that the highly ordered mesoporous MSPAN composite is a promising cathode active material for advanced Li−S batteries.

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