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Full-Text Articles in Engineering

Enhanced Reversible Lithium Storage In A Nanosize Silicon/Graphene Composite, Shulei Chou, Jiazhao Wang, Mohammad Choucair, Hua Liu, John Stride, S Dou Nov 2012

Enhanced Reversible Lithium Storage In A Nanosize Silicon/Graphene Composite, Shulei Chou, Jiazhao Wang, Mohammad Choucair, Hua Liu, John Stride, S Dou

Shulei Chou

Si/graphene composite was prepared by simply mixing of commercially available nanosize Si and graphene. Electrochemical tests show that the Si/graphene composite maintains a capacity of 1168 mAh g-1 and an average coulombic efficiency of 93% up to 30 cycles. EIS indicates that the Si/graphene composite electrode has less than 50% of the charge-transfer resistance compared with nanosize Si electrode, evidencing the enhanced ionic conductivity of Si/graphene composite. The enhanced cycling stability is attributed to the fact that the Si/graphene composite can accommodate large volume charge of Si and maintain good electronic contact.


One-Step Spray Pyrolysis Synthesized Cuo-Carbon Composite Combined With Carboxymethyl Cellulose Binder As Anode For Lithium-Ion Batteries, Chao Zhong, Jia-Zhao Wang, Xuan-Wen Gao, Shulei Chou, Konstantin Konstantinov, Hua Liu Nov 2012

One-Step Spray Pyrolysis Synthesized Cuo-Carbon Composite Combined With Carboxymethyl Cellulose Binder As Anode For Lithium-Ion Batteries, Chao Zhong, Jia-Zhao Wang, Xuan-Wen Gao, Shulei Chou, Konstantin Konstantinov, Hua Liu

Shulei Chou

Copper oxide-carbon composite with hollow sphere structure has been synthesized by a one-step spray pyrolysis method and tested as anode material for lithium-ion batteries. Different analytical methods, including X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and systematic electrochemical tests were performed. The results demonstrate that the CuO-carbon composite in conjunction with carboxymethyl cellulose (CMC) binder has an excellent electrochemical performance, with a capacity of 577 mAh g-1 up to 100 cycles. The usage of the water soluble binder, CMC, not only obviously improves the electrochemical performance, but also makes the electrode fabrication process much easier and …


Hierarchy Of Supramolecular Synthons In The Of Design Multi-Component Crystals, Padmini Kavuru Jun 2012

Hierarchy Of Supramolecular Synthons In The Of Design Multi-Component Crystals, Padmini Kavuru

USF Tampa Graduate Theses and Dissertations

Most of the biological systems in nature are sustained by molecular self-assemblies which are the finest examples of supramolecular architectures. Non-covalent interactions are key concepts which govern these molecular assemblies. Inspired by these examples crystal engineering emerged as an important tool in supramolecular chemistry which aids in the invention of new molecular structures with desired properties. Understanding of how the molecules interact at the molecular levels enables one to rationally design novel solid forms with modulated physicochemical properties. This feature of crystal engineering has heightened its position in materials chemistry and is currently one of the most well studied fields …


K0.25mn2o4 Nanofiber Microclusters As High Power Cathode Materials For Rechargeable Lithium Batteries, Chaofeng Zhang, Chuanqi Feng, Peng Zhang, Zaiping Guo, Zhixin Chen, Sean Li, Hua-Kun Liu Jan 2012

K0.25mn2o4 Nanofiber Microclusters As High Power Cathode Materials For Rechargeable Lithium Batteries, Chaofeng Zhang, Chuanqi Feng, Peng Zhang, Zaiping Guo, Zhixin Chen, Sean Li, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

K0.25Mn2O4 microclusters assembled from single-crystalline nanofibers were synthesized via a hydrothermal process at different temperatures. The possibility of using these materials as cathode material for lithium ion batteries was studied for the first time. The charge/discharge results showed that the K0.25Mn2O4 nanofiber microclusters synthesized at 120 degrees C exhibit excellent lithium storage properties, with a high reversible capability (360 mA h g-1 at current density of 100 mA g-1) and stable lithium-ion insertion/de-insertion reversibility. The charge/discharge mechanism in lithium ion batteries was studied and proposed for the …


Free-Standing Single-Walled Carbon Nanotube/Sno2 Anode Paper For Flexible Lithium-Ion Batteries, Lukman Noerochim, Jia-Zhao Wang, Shulei Chou, David Wexler Jan 2012

Free-Standing Single-Walled Carbon Nanotube/Sno2 Anode Paper For Flexible Lithium-Ion Batteries, Lukman Noerochim, Jia-Zhao Wang, Shulei Chou, David Wexler

Australian Institute for Innovative Materials - Papers

Free-standingsingle-walledcarbonnanotube/SnO2 (SWCNT/SnO2) anodepaper was prepared by vacuum filtration of SWCNT/SnO2 hybrid material which was synthesized by the polyol method. From field emission scanning electron microscopy and transmission electron microscopy, the CNTs form a three-dimensional nanoporous network, in which ultra-fine SnO2 nanoparticles, which had crystallite sizes of less than 5 nm, were distributed, predominately as groups of nanoparticles on the surfaces of singlewalled CNT bundles. Electrochemical measurements demonstrated that the anodepaper with 34 wt.% SnO2 had excellent cyclic retention, with the high specific capacity of 454 mAh g−1 beyond 100 cycles at a current …


Microporous Gel Polymer Electrolytes For Lithium Rechargeable Battery Application, Nurul Hayati Idris, Md. Mokhlesur Rahman, Jia-Zhao Wang, Hua-Kun Liu Jan 2012

Microporous Gel Polymer Electrolytes For Lithium Rechargeable Battery Application, Nurul Hayati Idris, Md. Mokhlesur Rahman, Jia-Zhao Wang, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

Microporous poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) membranes were prepared using the phase-separation method. Then, the membranes were immersed in liquid electrolyte to form polymer electrolytes. The effects of PMMA on the morphology, degree of crystallinity, porosity, and electrolyte uptake of the PVDF membrane were studied. The addition of PMMA increased the pore size, porosity and electrolyte uptake of the PVDF membrane, which in turn increased the ionic conductivity of the polymer electrolyte. The maximum ionic conductivity at room temperature was 1.21 × 10−3 S cm−1 for Sample E70. The polymer electrolyte was investigated, along with lithium iron phosphate (LiFePO4) as cathode …


Lifepo4-Fe2p-C Composite Cathode: An Environmentally Friendly Promising Electrode Material For Lithium-Ion Battery, M. Mahfuzur Rahman, Jiazhao Wang, Rong Zeng, David Wexler, Hua-Kun Liu Jan 2012

Lifepo4-Fe2p-C Composite Cathode: An Environmentally Friendly Promising Electrode Material For Lithium-Ion Battery, M. Mahfuzur Rahman, Jiazhao Wang, Rong Zeng, David Wexler, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

In this investigation, the synthesis strategy is involved the creation of LiFePO4-Fe2P-C composites with a porous conductive architecture, which includes distinct regions or clusters containing antiferromagnetic LiFePO4 in close proximity to ferromagnetic Fe2P. The microstructure is achieved by using a simple ultra-fast solvent assisted manual grinding method, combined with solid state reaction, which can replace the time-consuming high energy ball milling method. The crystalline structure, morphology, and electrochemical characterization of the synthesised product are investigated systematically. The electrochemical performance is outstanding, especially the high C rate. The composite cathode is found to display specific capacity of 167 mAh g-1 at …


Irradiation Si On Carbon Nanotube Paper As A Flexible Anode Material For Lithium-Ion Batteries, Shulei Chou, Mihail Ionescu, Jia-Zhao Wang, Brad Winton, Hua-Kun Liu Jan 2012

Irradiation Si On Carbon Nanotube Paper As A Flexible Anode Material For Lithium-Ion Batteries, Shulei Chou, Mihail Ionescu, Jia-Zhao Wang, Brad Winton, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

Silicon single walled carbon nanotube composite paper was modified by low energy ion implantation using 5i to obtain a flexible composite paper. Raman and FE-SEM results show that structure of SWCNT could be destroyed by the implantation. Electrochemical measurements display that the implanted SI can improve the specific capacity and the reversible capacity of CNT paper. After 50 cycles, the specific capacity of 5Hmplanted CNT paper is 30 per cent higher than the pristine CNT.