Tetsu Ichitsubo 교수

By utilizing ultrasonic annealing at a temperature below (or near) the glass transition temperature Tg, we revealed a microstructural pattern of a partially crystallized Pd-based metallic glass with a high-resolution electron microscopy. On the basis of the observed microstructure, we inferred a plausible microstructural model of fragile metallic glasses composed of strongly bonded regions surrounded by weakly bonded regions (WBRs). The crystallization in WBRs at such a low temperature under the

On the basis of the similarity between spinel and rocksalt structures, it is shown that some spinel oxides (e.g., MgCo₂O₄, etc) can be cathode materials for Mg rechargeable batteries around 150 °C. The Mg insertion into spinel lattices occurs via "intercalation and push-out" process to form a rocksalt phase in the spinel mother phase. For example, by utilizing the valence change from Co(III) to Co(II) in MgCo₂O₄, Mg insertion occurs at a considerably h

In this work, we propose and examine a battery system with a new design concept. The battery consists of a non-noble polyvalent metal (such as Ca, Mg, Al) combined with a positive electrode already well-established for lithium ion batteries (LIBs). The prototype demonstrated here is composed of a Mg negative electrode, LiFePO4 positive electrode, and tetrahydrofuran solution of two kinds of salts (LiBF4 and phenylmagnesium chloride) as an electrolyte. The LIB positive-electrode materials such as

Magnesium-ion batteries (MIBs) with a Mg-metal negative electrode are expected to combine high energy density and high electromotive force, owing to the divalent ion careers and its low redox potential. However, it has been reported to date that the cell voltage of MIBs is not high enough (∼1.5 V), being far below that of lithium-ion batteries (LIBs) (4–5 V). In this work, we have investigated the potentiality of Mg–Co–O and Mg–Ni–O complex oxides as the positive electrode for MIBs, which are co

This work is devoted to fundamental electrochemistry on a novel concept of rechargeable battery, "rocking-chair type" Mg–Li dual-salt battery, in which both Mg and Li cations are carrier ions.

In lithium-ion batteries, Li ions usually infiltrate into the anode active material, which usually leads to the formation of Li compounds with expanding volumes. It is well known that the volume strain associated with dilatation/contraction at the intercalation/deintercalation cycles gradually deteriorates the electrode. The intention of this work devoting a simple Li/Sn battery system is to clearly show that such a mechanical strain accompanied by the formation of the Li–Sn compounds causes the

A stable metallic glass, SMG, is often viewed as an amorphous alloy exhibiting a reversible $\text{glass}\ensuremath{\leftrightarrow}\text{liquid}$ transition. Here we show experimentally that even in a less-stable metallic glass, LMG, which is prepared only by rapid melt quenching and promptly crystallized without glass transition at the ordinary heating rate, sufficiently rapid heating exposes the $\text{glass}\ensuremath{\rightarrow}\text{liquid}$ transition by suppressing crystallization. Th

It has been reported that the structural stability is significantly deteriorated under radio-frequency-ultrasonic perturbation at relatively low temperatures, e.g., near/below the glass transition temperature T(g), even for thermally stable metallic glasses. Here, we consider an underlying mechanism of the ultrasound-induced instability, i.e., crystallization, of a glass structure to grasp the nature of the glass-to-liquid transition of metallic glasses. Mechanical spectroscopy analysis indicate