Taketsugu Hirai

Electrochemistry of anatase titanium dioxide in lithium nonaqueous cells

Abstract The electrochemical behavior of anatase TiO2 (>108 ohm cm) was examined in 1M LiClO4-propylene carbonate/tetrahydrofuran solution at 30 °C. The Li/anatase TiO2 cell showed a stable working voltage of 1.780± 0.005 V under a low continuous drain below 20 mA g−1. The high rate performance (ca. 700 mA g−1), without the addition of any conductive binders, was also demonstrated in laboratory cells. The reaction mechanism of anatase TiO2 in lithium nonaqueous cells is discussed, in terms of topotactic lithium insertion into the anatase TiO2 matrix up to 1 Fr mole−1, using X-ray diffraction, in situ optical and electrochemical data.

Topotactic Reduction of Alpha‐Manganese (Di)Oxide in Nonaqueous Lithium Cells

Electrochemical reduction of synthetic α-MnO 2 s was examined in nonaqueous lithium cells. Synthetic α-MnO 2 s containing NH 4 + (empirical formula (NH 4 ) 1.4(1) Mn 8 O 16 , MnO 1.908 ), K + (K 1.3(1) Mn 8 O 16 , MnO 1.913 ), and Rb + ions (Rb 1.3(1) Mn 8 O 16 ,MnO 1.924 ) having tetragonal lattices were examined

Electrochemistry of L-niobium pentoxide a lithium/non-aqueous cell☆

The electrochemical behaviour of L-Nb2O5 (orthorhombic; a = 6.162, b = 3.661, c = 3.919 A) was examined in a 1 M LiClO4-propylene carbonate/ tetrahydrofuran (1:1) solution at 30 °C. L-Nb2O5 exhibited an S-shaped discharge curve (mid-point about 1.58 V) under a low, continuous drain below 5 mA g−1 without addition of any conductive binder (such as graphite or acetylene black) and it could be reduced up to 2 F mol−1. The performance of Li/Nb2O5 cells was examined: these were found to belong to the 1.5 V class of lithium cell at both low and high discharge rates. The reaction mechanism of L-Nb2O5 in a lithium/non-aqueous cell was investigated by ex situ X-ray diffraction analysis together with a chronopotentiometric technique. Reversibility tests indicated that the reaction of L-Nb2O5 was basically reversible over 0 – 2 F mol−1 of reduction, which agreed with the analytical results of ex situ XRD studies. The electrochemistry of L-Nb2O5, especially the characteristic S-shaped electrode potential curve, is discussed in terms of a homogeneous phase reaction.

Topotactic Two‐Phase Reaction of Ruthenium Dioxide (Rutile) in Lithium Nonaqueous Cell

Electrochemical and x-ray diffraction studies were carried out for the reduction of RuO 2 having rutile structure in 1M LiClO 4 propylene carbonate/1,2-dimethoxyethane (1:1) solution. RuO 2 was topotactically reduced to LiRuO 2 , drawing an L-shaped voltage curve

On a homogeneous electrochemical reaction of Prussian blue/Everitt's salt system

Voltammetric, chronopotentiometric, and spectroelectrochemical studies qn the homogeneous-phase (single phase) reaction of Prussian blue (PB)/Everitts salt (ES) system in KC1 aqueous solution were carried out as a model for understanding the homogeneous electrochemical reaction of manganese dioxide. Analytical results of voltammetric and chronopotentiometric studies on PB/ES system indicated that the electrode potential was represented by the empirical formula.

Electrolytic desulphinylation of 1-methylsulphinyl-1-methylthio-2-phenylethene in acetonitrile

Abstract The electrolytic reduction of (E)-1-methylsulphinyl-1-methylthio-2-phenylethene ( 1 ) in acetonitrile involves selective cleavage of one carbon-sulphur bond, resulting in formation of (E)-1-methylthio-2-phenylethene ( 2 ) in good yields, but not the (Z)-isomer, in the presence of excess phenol and benzoic acid, respectively, as proton donor and at all the following electrodes; mercury, platinum, lead, and glassy carbon. Polarographic studies of 1 and its related compounds such as 1,1-dimethylthio-2-phenylethene ( 3 ), (E)-1-methylsulphinyl-2-phenylethene ( 4 ), and 2 has revealed that the electrolytic reduction of 1 to 2 proceeds via neither 3 nor 4 , but via elimination of the methylsulphinyl group.

Cathodic elimination of 1-methylthio-1-p-tolylsulphonyl-2-arylethenes in non-aqueous media

Abstract The electrolytic reduction of 1-methylthio- p -tolylsulphonyl-2-arylethenes (1) in acetonitrile and N , N -dimethylformamide involves selective cleavage of a carbon—sulphur bond, resulting in formation of (E)-1-methylthio-2-arylethenes (2) in moderate yields with the consumption of about 2 electrons per mol, in the presence of efficient proton donors such as phenol and benzoic acid and at all the following electrodes; mercury, platinum, lead and glassy carbon. In the absence of proton donors, as was expected, the yield of 2 is very low and the hydrodimerization of 1 takes place.