Constant current electrolysis of flavones in DMF containing 0.1 mol dm-3 Bu4NBF4 in the presence of CO2 by using a one-compartment cell equipped with a Pt cathode and an Mg anode resulted in reductive carboxylation at the C2 position of flavones in a highly regioselective manner to give flavanone-2-carboxylic acids in moderate to good yields.
Three dimensionally ordered macroporous structure (3DOM) has characteristic features such as large surface area and open pores. Therefore, a composite electrode between active material and 3DOM electrolyte is anticipated to compensate small contact area between solid electrolyte and solid electrode. In this paper, electrochemical properties of TiO2/3DOM Li1.5Al0.5Ti1.5(PO4)3 (LATP) composite anode were examined. The TiO2/3DOM LATP composite was successfully prepared by colloidal crystal templating method and sol-gel method. The composite demonstrated clear charge and discharge plateau at 1.8 V vs. Li/Li+ attributed to redox of anatase TiO2, implying that the composite can be used as anode for lithium battery. Annealing temperature strongly affected on performance of the composite. The discharge capacity of composite annealing at 600°C was 89 mA h g-1 and this is higher than that annealed at 450°C. It is expected that fabrication of all-solid-state battery with better performance would be achieved by using TiO2/3DOM LATP anode.
We simulated grain growth of polycrystalline Cu thin film with impurities by the molecular dynamics method. The examined impurities were O and Ti of which the binding energy with Cu is strong and weak, respectively, and of which size is similar to matrix element Cu. The crystallinity and texture of the film were estimated by 2D-Fourier transformation of the atomic structure. The present study revealed that the impurity with strong binding energy and similar size to Cu atom segregated at the grain boundary and inhibited the grain growth. The obtained results showed good accordance with those obtained in actual experiments on Cu ultra-fine wires.
Liquid electrolytes for rechargeable Li-air batteries were chosen from viewpoints of the electrochemical stability against O2 radical, O2−. Mulliken atomic charges of electrolyte solvents and their reversibility of O2/O2− redox couple were first examined. In the carbonate-based electrolytes, the localization of positive charge in the molecules was confirmed, resulting in low reversibility of O2 radical. The electrolytes must be decomposed by the nucleophilic O2 radical. On the other hand, the nitrile-based and piperidinium-based electrolytes provided high O2 radical reversibility because all of the atomic charges in molecules and cations were either negative or almost zero. It was found that the electronic distribution of electrolyte solvents affected their electrochemical stability against O2 radical. Considering the electrochemical and chemical stability against Li metal, the piperidiniumbased ionic liquid was adopted as an electrolyte solvent in this study. The cell with piperidinium-based electrolyte achieved considerably low charging voltage of around 3.2 V and low voltage gap of about 0.75 V in the discharge-charge profiles, compared to conventional cells with carbonate-based electrolyte. It was, thus, concluded that the charging performances strongly influenced on the O2 radical stability of electrolyte solvent.
The combination of an electric double-layer capacitor (EDLC) and an “electrolyte charge storage system”, which is a completely novel charge storage method, was investigated. We screened p-type and n-type active materials and selected acetylferrocene for the former and 1, 1’-diheptyl-bipyridinium bis (tetrafluoroborate) for the latter. As a result, our capacitor effectively used the redox reactions of active materials dissolved in the electrolyte to increase its charge capacity. Self-discharge caused by the shuttle effect of active materials was almost suppressed using an anion-exchange membrane separator.