Navegando por Autor "Lavela, Pedro"
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Artigo Influence of Cosurfactant on the Synthesis of Surface-Modified Na2/3Ni1/3Mn2/3O2 as a Cathode for Sodium-Ion Batteries(Wiley, 2020-08-17) García-García, Francisco José; Lavela, Pedro; Klee, Rafael; Delmonte, Maurício Roberto Bomio; Tirado, José LuisThe electrochemicalperformanceof two Na2/3Ni1/3Mn2/3O2samples,preparedthroughan oleic-assistedemulsionproce-dure, is examined.The effect of cosurfactantswith either short(methylamine)or long (octylamine)chains is determinedfortheir applicabilityas cathodematerialsfor sodium-ionbatteries.Their structuraland morphologicalpropertiesare studiedby X-ray diffractionand electronmicroscopy.The electrochemicalperformanceis determinedby cyclingsodiumhalf-cellswiththe galvanostaticmethod.Particularinterestis devotedto theirkinetic propertiesevaluatedby using impedancespectroscopyArtigo Microwave-assisted hydrothermal synthesis of magnetite nanoparticles with potential use as anode in lithium ion batteries(UFSCar, 2014-09-09) Xavier, Camila Soares; Paskocimas, Carlos Alberto; Motta, Fabiana Villela da; Araújo, Vinícius Dantas; Aragón, Maria José; Tirado, José Luís; Lavela, Pedro; Silva, Elson Longo da; Delmonte, Maurício Roberto BomioRechargeable solid-state batteries have long been considered an attractive power source for a wide variety of applications, and in particular, lithium-ion batteries are emerging as the technology of choice for portable electronics. One of the main challenges in the design of these batteries is to ensure that the electrodes maintain their integrity over many discharge-recharge cycles. Fe3O4 deserves great attention as one of the most important electrode active materials due to its high theoretical capacity (926 mAhg - 1), low cost, being environmental-friendly and naturally abundance in worldwide. A simple strategy to synthesize magnetite nanoparticles (Fe3O4) by microwave-assisted hydrothermal method in a short processing time without further treatment is reported. The material obtained was tested as anode active material for lithium ions batteries. Impedance spectroscopy revealed that small differences in cell performance on cycling observed between samples cannot be strictly correlated to cell resistance. A high reversible capacity of 768.5 mAhg - 1 at 1C over 50 cycles was demonstrated, suggesting its prospective use as anode material for high power lithium ion batteriesArtigo On the use of guanidine hydrochloride soft template in the synthesis of Na2/3Ni1/3Mn2/3O2 cathodes for sodium-ion batteries(Elsevier, 2019-06-15) Aragon, Maria José; Ortiz, Gregório F.; Lavela, Pedro; Tirado, José Luís; Oliveira, J. D. C.; Motta, Fabiana Villela da; Delmonte, Maurício Roberto BomioSeveral P2-Na2/3Ni1/3Mn2/3O2 layered oxides have been prepared by a modified synthesis procedure using guanidine hydrochloride as a soft template. X-ray diffraction patterns will reveal a decrease of both crystallite size and strain for guanidine hydrochloride treated samples, favoring sodium accessibility at the electrode/electrolyte interface. Also, guanidine hydrochloride promotes anisotropic particles for intermediate amounts. This specific morphology may contribute to a partial suppression of the P2-O2 phase transition. Galvanostatic tests at different rates and potential windows will evidence better capacity retention and low charge-discharge hysteresis for NaNMO-2% in close relationship with the low internal resistance values at the electrode-electrolyte interphase and apparent diffusion coefficients determined by impedance spectroscopy. A performing full sodium-ion cell will demonstrate the reliability of this material as an electrode for Na-ion cells