Luis C. Torres-González

Electrochemical Aspects of Asymmetric Phosphonium Ionic Liquids

Abstract Print abstract Electrochemical Aspects of Asymmetric Phosphonium Ionic Liquids J. Electrochem. Soc., Volume 154, Issue 2, pp. B229-B233 (2007) Rosa E. Ramirez, Luis C. Torres-Gonzalez, and Eduardo M. SanchezLaboratorio de Investigacion del Vidrio, Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, NL Mexico 66450 (Revised 28 September 2006; published 26 December 2006) Asymmetric aliphatic tetraalkyl phosphonium cations form room-temperature ionic liquids with iodide as an anion. Isobutyl-trihexyl phosphonium iodide shows the highest ionic conductivity at room temperature and it is enhanced by 3-methoxypropionitrile addition. A cyclovoltammetric study shows adequate redox behavior for nanocrystalline solar cells devices. ©2006 The Electrochemical Society doi:10.1149/1.2404789 Additional Information View ISIs Web of Science data for this article: [ Source Abstract | Related Articles ] View Cart Full Text: HTML |Sectioned HTML| PDF |GZipped PS

Conductivity and viscosity behavior of asymmetric phosphonium iodides.

In this work, we report the physicochemical properties of a variety of aliphatic phosphonium iodide (API) salts, including thermal degradation. Also, we compared the conductivity, viscosity, and fragility behavior of APIs to similar molten systems and related these properties to their structure. Our investigation has found that APIs have an intermediate fragility behavior. We plotted the conductivity and viscosity data of APIs according to Waldens rule and found that they can be classified as an associated ionic liquid (AIL), an intermediate between a true ionic liquid and a molecular species. Lastly, we correlated the structure and behavior of APIs and similar polarizable anions, such as the diacetamide anion.

Aluminum doped Na3V2(PO4)2F3 via sol–gel Pechini method as a cathode material for lithium ion batteries

The solid solution series Na3V2-xAlx(PO4)2F3 (where x = 0, 0.02, 0.05, and 0.1) powders have been prepared using the Pechini method to study the effect of aluminum doping on the electrochemical properties of these cathode materials for lithium ion batteries. The structure, composition, and morphology of the compounds were investigated by X-ray diffraction, thermogravimetric and differential analysis, specific surface area, and pore size analysis using Brunauer-Emmett-Teller—Barret-Joyner-Halenda methods, scanning electron microscopy, elemental chemical analysis with induced coupled plasma-optical emission spectroscopy and charge/discharge galvanostatic experiments. X-ray diffraction indicates a tetragonal crystal structure for the Na3V2(PO4)2F3 phase, and all the Al compositions. The materials obtained have a microstructure consisting of nanoparticles (40–100 nm) with an average pore size 20 nm and 30 m2/g surface area. The phase with 0.05 moles of aluminum gave the best result electrochemical charge/discharge capacities of 123 to 101 mAh/g with cell voltage of 4.4 V vs. Li and a capacity retention of 82%, compared to undoped material which gave 128 to 63 mAh/g, and 49% capacity retention. Hence, Al-doped samples showed better electrochemical performance maybe attributable to improved structure stability compared to the undoped material. Those results suggest a promising material for lithium ion batteries.Graphical Abstract