Sharif Digital Repository

In the current century, burning fossil fuel for producing energy in human life such as in transportation applications leads to make problems, for example, global warming and climate change. Hence, researchers motivate to find out some clear renewable energy sources and design appropriate devices to store them. Rechargeable batteries and supercapacitors are two of the most important devices for energy storage. In the current century, they are playing a significant important role in communication, medical, and transportation devices. However, the electrochemical performances of rechargeable batteries and supercapacitors increasingly depend on the properties of their main components such as... 

Demand for high-capacity, long cycle life, and aqueous batteries based on abundant metals such as nickel, zinc, aluminum, and so on is rising in the energy storage field. In this study, we design a hierarchical morphology as a nanosheet-built microsphere of nickel vanadium layered double hydroxide (NiV LDH) with conductive agents graphene oxide (GO) and multiwalled carbon nanotubes (CNTs) through a low-cost hydrothermal synthesis method. The experimental results demonstrate that the graphitic structures and functional groups of the GO and CNT play an important role in controlling nucleation, growth speed, size, and finally morphology of hierarchical nanosheets. The electrochemical results... 

Nickel-zinc batteries as safe and economic energy storage devices suffer from lack of high electrochemical performance of cathode materials. Herein, a new cathode material for rechargeable Ni/Zn batteries is introduced based on various compositions of mixed metal oxide (MMO) through a calcination process of nickel-vanadium layered double hydroxide at different temperatures. The results demonstrated that the prepared sample at 500 °C presents the best electrochemical properties such as a good electrochemical discharge capacity (278.4 mAh g-1 at 0.5 A g-1), good cycle life (capacity retention of 74% after 1000 cycles at 5 A g-1), and excellent rate capability (177 mAh g-1 at 5 A g-1). These... 

This paper deals with investigation of deformations and pull-in charges of the cantilever and doubly clamped carbon nanotubes (CNTs) with different geometries using molecular dynamics simulation technique. The well-known AIREBO potential for the covalent bonds between carbon atoms, Lennar-Jones potential for the vdW interaction and the Coulomb potential for electrostatic actuation are employed to model the nano electromechanical system. The results reveal that longer CNTs with smaller diameters have smaller pull-in charges in comparison with shorter CNTs possessing larger diameters. Furthermore, the pull-in charges of the doubly clamped CNTs are higher than the pull-in charges of the... 

In this work, we reported the synthesis of a sulfonated poly(ether keto imide sulfone) (SPEKIS) using a novel aromatic diol containing nitrogen heterocycles and sulfonic monomer. New nanocomposite blend membranes were prepared using obtained SPEKIS and polybenzimidazole (PBI) with the incorporation of zinc sulfide (ZnS) functionalized quantum dots (FQDs) having both -COOH and NH2 groups with a solution-casting method and were used as proton exchange membranes. The SPEKIS and ZnS FQDs were used for the first time in the preparation of new nanocomposite blend membranes based on PBI. The purpose of this study is to investigate the effect of SPEKIS and ZnS FQDs on the PBI membrane performance in... 

In this study, we prepared cerium oxide (CeO2) hybridized with reduced graphene oxide (rGO) nanosheets using the hydrothermal method. CeO2 and CeO2/rGO were evaluated as electrode materials for use in supercapacitor applications. The structure and morphology of the synthesized materials were investigated. Cyclic voltammetry tests determined a high specific capacitance of 581 F g−1 for CeO2/rGO at a scan rate of 10 mV s−1 in 2 M KOH. In addition, the CeO2/rGO electrode retained 91 % of its initial capacitance after 5000 consecutive cycles, thereby indicating its excellent electrochemical stability. The excellent stability of CeO2/rGO was due to a synergistic effect between CeO2 and rGO. CeO2... 

The anode materials are one of the critical components in rechargeable lithium ion batteries (LIBs). The monoclinic tungsten trioxide (mWO3) is introduced as interesting anode electrode for LIBs due to its good structure for intercalation and de-intercalation of lithium ions, high abundance and various oxidation state of tungsten and etc. In this study, we prepare and investigate the effect of various amounts of nickel dopant on characteristics and electrochemical properties of the mWO3 as the anode electrode in a rechargeable LIB. The experimental investigations confirm that the number of nickel atoms has a remarkable effect on controlling spherical particle diameter, crystallite size, and... 

In this study, new nanocomposite membranes from sulfonated poly (ether ether ketone) (SPEEK) and proton-conducting Fe2TiO5 nanoparticles are prepared by the solution casting method. Sulfonated core-shell Fe2TiO5 nanoparticles are synthesized by redox polymerization. Therefore, 4-Vinyl benzene sulfonate (VBS) and 2-acrylamide-2-methyl-1-propane sulfonic acid (AMPS) are grafted on the surface of nanoparticles through radical polymerization. The different amounts of hybrid nanoparticles (PAMPS@Fe2TiO5 and PVBS@Fe2TiO5) are incorporated into the SPEEK matrix. The results show higher proton conductivity for all prepared nanocomposites than that of the SPEEK membrane. Embedding the sulfonated...