Journal of the Electrochemical Society

Kuriyama, Nobuhiro; Sakai, Tetsuo; Miyamura, Hiroshi; Uehara, Itsuki; Ishikawa, Hiroshi; Iwasaki, Toshikatsu

doi: 10.1149/1.2221180pmid: N/A

Electrochemical impedance spectrum of a metal hydride electrode was interpreted by an equivalent circuit including a reaction resistance on the alloy surface, a contact resistance between the current collector and the pellet, one related to alloy particle‐to‐particle contact, and a Warburg impedance. According to the interpretation, deterioration of a metal hydride electrode using copper‐coated alloy powder was found to be caused by passivation of the alloy surface only. On the other hand, deterioration of an electrode using uncoated alloy was dominated by increase of the contact resistances.

Malem, Franck; Mandler, Daniel

doi: 10.1149/1.2221177pmid: N/A

An easy approach for constructing gold electrodes embedded in glass is described. A special “soft” glass, with a thermal expansion coefficient matching that of gold has enabled us to assemble gold electrodes which exhibit good sealing and thus excellent electrochemical response.

Lawson, Del R.; Feldheim, Daniel L.; Foss, Colby A.; Dorhout, Peter K.; Elliott, C. Michael; Martin, Charles R.; Parkinson, Bruce

doi: 10.1149/1.2221179pmid: N/A

can exist in a number of oxidation states including , , , and . We describe in this paper near‐IR absorption peaks which are unique to these four oxidation states. These peaks are observed upon one, two, three, and four electron electrochemical reductions of . We have rationalized the energies and intensities of these electronic absorptions based on modifications of the known molecular orbital diagram of . The near‐IR absorptions reported here should provide a clear and unambiguous route for determining the oxidation state of in solution.

Snyder, D. W.; Sides, P. J.; Ko, E. I.

doi: 10.1149/1.2221178pmid: N/A

Helium and nitrogen were substituted for hydrogen as a carrier gas in the thermally activated organometallic vapor phase epitaxy of cadmium telluride. The deposition rate decreased markedly and the decrease depended on the particular gas (helium or nitrogen), tellurium precursor (diethyltellurium or diisopropyltellurium), and crystal orientation of the cadmium telluride substrate. Deposition ceased entirely when helium or nitrogen was substituted for hydrogen, the alkyl was diethyltellurium, and the crystal orientation was (111)Cd.

Carter, Michael T.; Osteryoung, Robert A.

doi: 10.1149/1.2069500pmid: N/A

The electrochemical behavior of 9, 10‐anthraquinone (AQ) in a basic room‐temperature molten salt composed of a mixture of and 1‐ethyl‐3‐methylimidazolium chloride is described. In the absence of a proton source, AQ is reduced via a quasireversible two‐electron transfer to . The homogeneous chemical steps coupled to the electron transfers are displacement of Cl− from to form . Addition of a proton source, imidazolium hydrogen dichloride , causes the coupled chemical reactions to shift from solvent leveling of reduced AQ by to more facile protonation steps. Visible spectroscopy of AQ in 0.8:1 melt and neat show that AQ is present as the neutral, unprotonated quinone in its oxidized form. The two‐electron, two‐proton reduction product 9, 10‐dihydroxyanthracene is formed under these conditions but is unstable in the melt. It is converted to , which is the reoxidizable form, regardless of whether protons are present in the melt. is stable on the voltammetric time scale in neat . Under these conditions, the hydroquinone is formed exclusively and the electrochemistry tends toward that of the classical 2 e−, 2 H+ case found in aqueous systems. Experiments in molten , at 90°C, show that the quinone anion radical and dianion are stable only under conditions where no Lewis acid is available for adduct formation.

Choi, Yong‐Kook; Seo, Seong‐Seob; Chjo, Ki‐Hyung; Choi, Q‐Won; Park, Su‐Moon

doi: 10.1149/1.2069501pmid: N/A

Effects of temperatures, at which electrodes were prepared by thermal oxidation from titanium sheet metals, as well as platinum loading, on electrochemical and photoelectrochemical properties have been studied and the results are reported. Titanium dioxide electrodes prepared at higher temperatures were found to have slightly more negative flatband potentials and significantly higher donor densities than their low temperature counterparts. Platinum loading showed a similar effect to a lesser extent. Improved oxygen reduction kinetics and photoelectrochemical responses were observed at both the electrodes prepared at higher temperatures and platinum loaded electrodes; the oxygen reduction was affected by platinum loading more at oxide electrodes prepared at low temperatures than those prepared at high temperatures.

Doeff, M. M.; Visco, S. J.; De Jonghe, L. C.

doi: 10.1149/1.2069502pmid: N/A

Thin‐film solid‐state batteries consisting of lithium foils, amorphous PEO separators, and solid redox polymerization electrodes (SRPEs) were assembled, discharged, and cycled at room temperature. No solvents were added to any of the components, nor were structural additives used. Performances were studied as a function of cathode thickness and composition of separator and SRPE. At 50 μA/cm2, cells could be discharged to a depth of 0.6 to 1.3 C/cm2, at 100 μA/cm2 to a depth of 0.5 C/cm2, and at 200 μA/cm2 to a depth of 0.25 C/cm2. It was also possible to pulse batteries at higher current densities for short periods of time (ranging from 0.1 to 3 s) with instantaneous recovery of open‐circuit potential after the pulses. One cell was cycled 100 times, with inadvertent overdischarge and overcharge, before significant deterioration of performance occurred. Batteries may be designed to be paper thin, or may consist of several cells stacked together to give a somewhat thicker device. Practical energy and power densities were calculated as a function of component dimensions (cathode and current collector thicknesses) for paper thin batteries consisting of lithium anodes, amorphous PEO separators, SRPEs, and metallized plastic current collectors. Power densities of 30 W/l (continuous discharge) and pulse (0.1 s power densities over 1000 W/l may be achieved for these ultrathin devices.

Frankel, G. S.; Davenport, A. J.; Isaacs, H. S.; Schrott, A. G.; Jahnes, C. V.; Russak, M. A.

doi: 10.1149/1.2069503pmid: N/A

Oxides grown electrochemically in a borate buffer solution on the surface of sputter‐deposited alloy films were studied by x‐ray absorption near edge structure (XANES). The measurements were made in air immediately following polarization in solution. The oxides were also examined with x‐ray photoelectron spectroscopy (XPS). The effects of alloy composition and thickness as well as applied potential were studied. Cr(VI) was found in the oxides if the applied potential was sufficiently high. The Cr(VI) was enriched at the interface with the electrolyte and the proportion of Cr(VI) in the oxide was higher for alloy films containing more Cr. The Cr(VI) in the oxides could be reversibly reduced to Cr(III) and reoxidized to Cr(VI) by subsequent potentiostatic treatments in solution.

Hikino, S.; Xie, Gang; Ema, K.; Ito, Y.; Shou, Zhao Min

doi: 10.1149/1.2069504pmid: N/A

The electrochemical reduction of yttrium ion on a molybdenum electrode in a eutectic melt at 723 K was found to be almost reversible and to proceed by a one‐step three electron reaction. The diffusion coefficient D of the Y(III) ion was measured to be by cyclic voltammetry, by the rotating disk electrode method, and by chronopotentiometry. The D values obtained by the latter two methods are in fairly good agreement with each other. The rather low D value obtained by cyclic voltammetry might be attributed to the fact that yttrium metal can dissolve slightly in the chloride melt. The standard potential of Y(III)/Y(0) couple was determined to be V (vs. ) by open‐circuit potentiometry, V (vs. ) by the rotating disk electrode method and V (vs. ) by chronopotentiometry. These three values are in good agreement with each other. Several types of Ni‐Y intermetallic compounds were found to be formed on a nickel electrode.

Kuwabata, Susumu; Mitsui, Kazuki; Yoneyama, Hiroshi

doi: 10.1149/1.2069505pmid: N/A

Polyaniline films containing methylene blue were electrochemically prepared using polymerized tetrafluorosulfonate (Nafion) as an electrolyte anion which worked well for electrostatic binding of methylene blue and served as a charge compensator for oxidized polyaniline. The incorporated methylene blue was reduced by illumination of the polyaniline film in solution containing 0.1M ascorbic acid. The rate of photoreduction was enhanced by further incorporating. The role of the incorporated on the photoreduction rate of the incorporated methylene blue was quantitatively analyzed by measuring photoelectrochemical properties of the films, and discussed based on energy diagrams. Furthermore, the effectiveness of the use of conductive polyaniline matrix in comparison with the matrix of Nafion alone was demonstrated. The photoreduction of methylene blue in such films could successfully be utilized in the formation of light images.