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Wang X.,Beijing Research Institute of Chemical Defense
Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering | Year: 2011

In order to improve the attenuation effect of oil fog smoke on 10.6 μm laser emission, the mass extinction coefficient to 10.6 μm laser emission and distribution rule of granularity of oil fog caused by superfine graphite and oil fog smoke which was produced by oil smoke producer were tested in flat and wide outfield. Experimental results show oil fog combined with superfine graphite has larger attenuation effect on 10.6 μm laser emission and bigger average diameter than pure oil fog. The average diameter increases 87.8% and the extinction coefficient to 10.6 μm laser emission increases 122%. By analysis, the extinction performance of oil fog smoke will be enhanced with the increase of the average diameter of the smoke's particles when the diameter is smaller than 10.2 μm. As a result, the extinction performance of oil fog to 10.6 μm laser emission may be remarkably improved by enhancing the smoke's granularity through producing oil fog combined with graphite particles which have a bigger diameter. Source


Ni J.,Soochow University of China | Wang Y.,Beijing Research Institute of Chemical Defense
RSC Advances | Year: 2015

Lithium iron phosphate (LiFePO4) is an appealing cathode material for lithium ion batteries. However, the degradation of LiFePO4 in air presents an unavoidable challenge, due to the vulnerability of divalent Fe against oxygen attack. In this work, we have carried out comprehensive research on the thermal stability and temperature-driven evolution of nanocarbon modified LiFePO4 in air. The results show that LiFePO4 retains structural stability up to 250°C for short periods of exposure to air. At long exposure times, structural evolution occurs at a much lower temperature, 150°C. The structural evolution proceeds as the temperature increases, and finishes at 400°C. The final products are monoclinic Li3Fe2(PO4)3 and α-Fe2O3. A quantitative evolution map has been developed through electrochemical cyclic voltammetry and galvanostatic tests. The results show that the largest changes take place between 200 and 250°C. © The Royal Society of Chemistry 2015. Source


Zhang X.,Beijing Institute of Technology | Sui Z.,Beijing Institute of Technology | Xu B.,Beijing Research Institute of Chemical Defense | Yue S.,Beijing Research Institute of Chemical Defense | And 3 more authors.
Journal of Materials Chemistry | Year: 2011

Mechanically strong and electrically conductive graphene aerogels can be prepared by either supercritical drying or freeze drying of hydrogel precursors synthesized from reduction of graphene oxide with l-ascorbic acid, and the resulting graphene aerogels possess the specific capacitance of 128 F g -1 with superior rate performance. © 2011 The Royal Society of Chemistry. Source


Xu B.,Beijing Research Institute of Chemical Defense | Hou S.,China University of Mining and Technology | Cao G.,Beijing Research Institute of Chemical Defense | Wu F.,Beijing Institute of Technology | Yang Y.,Beijing Research Institute of Chemical Defense
Journal of Materials Chemistry | Year: 2012

Gelatin, a renewable animal derivative composed of various proteins, was used as a precursor for nitrogen-doped porous carbon with high surface areas for supercapacitors for the first time. The preparation procedure is very simple, including the carbonization of gelatin under inert atmosphere, followed by NaOH activation of the carbonized char at 600 °C for 1 h. The porosity and surface chemistry of the carbon depend strongly on the weight ratio of NaOH/char, with the specific surface area and nitrogen content varying between 323 and 3012 m 2 g -1 and between 0.88 and 9.26 at%, respectively. The unique microstructure and nitrogen functionalities enable the carbon to exhibit a high capacitance of up to 385 F g -1 in 6 mol L -1 KOH aqueous electrolytes, attributed to the co-contribution of double layer capacitance and pseudo-capacitance. It also shows excellent rate capability (235 F g -1 remained at 50 A g -1) and cycle durability, making it a promising electrode material for supercapacitors. This journal is © The Royal Society of Chemistry. Source


Miao L.-X.,Beijing Institute of Technology | Miao L.-X.,Beijing Research Institute of Chemical Defense | Wang W.-K.,Beijing Research Institute of Chemical Defense | Wang A.-B.,Beijing Research Institute of Chemical Defense | And 2 more authors.
Journal of Materials Chemistry A | Year: 2013

Lithium-sulfur (Li-S) batteries have received significant attention in recent years because of their high theoretical specific capacity (1675 mA h g-1) and energy density (2600 W h kg-1). Many papers focus on cells that exhibit very high capacity per gram of sulfur, which contain sulfur contents well below 50% which greatly reduces their overall energy density per gram of cathode. Moreover, they do not address the issues of practical sulfur loading and large-scale technology for commercial applications. In general, the lower the sulfur content, the higher the sulfur capacity. In this paper, a high sulfur content (80% S) carbon-sulfur (P-AB@S) material with core-shell structure has been successfully synthesized by grafting of polymer electrolyte (polyethylene glycol, PEG) chains and depositing sulfur onto the surface of electronically conductive acetylene black (AB). The PEG chains are inserted into the sulfur layer to reinforce the material's structural stability. More importantly, with a cathode containing 66% sulfur and approximately 3 mg cm-2 sulfur loading on the electrode, P-AB@S as a cathode material for lithium sulfur batteries shows a specific capacity of 577 mA h g -1 after 500 cycles at 100 mA g-1 between 1.5 V and 2.8 V. Moreover, the preparation method of the P-AB@S composite is a facile, cost-effective and template-free method and easy to implement large-scale technology for commercial applications. © 2013 The Royal Society of Chemistry. Source

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