Hiroyuki Usui
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View article: Mesoporous Spheres Comprised of Rutile TiNbO<sub>4</sub> Particles for Na Storage Materials
Mesoporous Spheres Comprised of Rutile TiNbO<sub>4</sub> Particles for Na Storage Materials Open
We prepared rutile-type TiNbO4 by a sol-gel method to investigate the relationship between the calcination temperature in the synthesis and its nanostructure and evaluated the influence of the nanostructure on the electrode properties as a…
View article: Nickel-Doped Titanium Oxide with the Rutile Structure for High-Performance Sodium Storage
Nickel-Doped Titanium Oxide with the Rutile Structure for High-Performance Sodium Storage Open
We prepared rutile TiO2 particles doped with Ni2+, Al3+, Nb5+, and Ta5+ by hydrothermal synthesis as anode materials for Na-ion batteries and investigated the effect of doping cation valence on the anode performance and the Na+ diffusion b…
View article: Electrochemical Lithiation Mechanism of Nickel Silicide Electrode
Electrochemical Lithiation Mechanism of Nickel Silicide Electrode Open
Pure silicide electrodes have attracted attention as a promising anode material in lithium-ion batteries using certain ionic liquid electrolytes. However, the reaction mechanisms of silicide electrodes, particularly the lithiation sites in…
View article: Sn<sub>4</sub>P<sub>3</sub>/Sb Composite Electrodes as High-Performance Anodes for Li-Ion and Na-Ion Storages
Sn<sub>4</sub>P<sub>3</sub>/Sb Composite Electrodes as High-Performance Anodes for Li-Ion and Na-Ion Storages Open
Various composite electrodes were prepared using Sn4P3 and other active materials (Sb, Bi, Ge, TiO2, In, and Fe) with weight ratios of 70 and 30 wt% for Na-ion battery anode to improve capacity decay of Sn4P3 caused by Sn aggregation. No i…
View article: Silicon-Based Nanocomposite Anodes with Excellent Cycle Life for Lithium-Ion Batteries Achieved by the Synergistic Effect of Two Silicides
Silicon-Based Nanocomposite Anodes with Excellent Cycle Life for Lithium-Ion Batteries Achieved by the Synergistic Effect of Two Silicides Open
Nanocomposite electrodes comprising LaSi 2 and Si exhibit satisfactory charge–discharge cycling performances but their capacity is degraded after repeated cycles. A metallographic structure, in which the Si phase was finely dispersed in th…
View article: Coating of Chlorophylls <i>a</i> and <i>b</i> Enhanced Photoelectrochemical Capacitor Reaction of TiO<sub>2</sub>/MnO<sub>2</sub> Composite Electrode
Coating of Chlorophylls <i>a</i> and <i>b</i> Enhanced Photoelectrochemical Capacitor Reaction of TiO<sub>2</sub>/MnO<sub>2</sub> Composite Electrode Open
We prepared composite electrodes using TiO2 coated with chlorophylls a and b as photoelectric conversion material and MnO2 as energy storage material and investigated their photoelectrochemical capacitor properties. The coating with the co…
View article: Electrochemical Anode Behavior of α-FeSi<sub>2</sub> Co-Sintered with Solid Electrolyte
Electrochemical Anode Behavior of α-FeSi<sub>2</sub> Co-Sintered with Solid Electrolyte Open
It is essential in the production of the next generation of rechargeable batteries to elucidate the reaction phases formed after co-sintering in all-solid-state batteries with oxide solid electrolytes and silicon materials and their electr…
View article: Anode Properties of Sb-Based Alloy Electrodes for K-Ion Batteries in an Ionic-Liquid Electrolyte
Anode Properties of Sb-Based Alloy Electrodes for K-Ion Batteries in an Ionic-Liquid Electrolyte Open
Maintaining the sustainability of society demands the strategic use of multipurpose rechargeable batteries. One promising option is K-ion batteries (KIBs), which are suitable as large stationary storage batteries and store renewable energy…
View article: Na-storage reactions of rutile TiNbO4
Na-storage reactions of rutile TiNbO4 Open
As a novel anode material for Na-ion battery, we evaluated rutile-type TiNbO4 synthesized by a sol−gel method. It was revealed for the first time that TiNbO4 showed reversible reactions of Na+-insertion and Na+-extraction in the potential …
View article: NASICON-type Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> Containing Amorphous Phase for Solid Li-Ion Conductor
NASICON-type Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> Containing Amorphous Phase for Solid Li-Ion Conductor Open
Amorphous Li1.5Al0.5Ge1.5(PO4)3 (LAGP), which is an oxide-based solid electrolyte with a NASICON-type structure, was sintered at various temperatures to investigate its ionic conductivity and potential windows. The LAGP sheet sintered at 6…
View article: TiO<sub>2</sub> Anode Material for All-Solid-State Battery Using NASICON Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> as Lithium Ion Conductor
TiO<sub>2</sub> Anode Material for All-Solid-State Battery Using NASICON Li<sub>1.5</sub>Al<sub>0.5</sub>Ge<sub>1.5</sub>(PO<sub>4</sub>)<sub>3</sub> as Lithium Ion Conductor Open
We have been developing sintered multilayer oxide-based all-solid-state batteries. Anode active material rutile-type TiO2 was not reacted with amorphous Na superionic conductor (NASICON)-type solid electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) …
View article: Rutile TiO<sub>2</sub> Creates Advanced Na-Storage Materials
Rutile TiO<sub>2</sub> Creates Advanced Na-Storage Materials Open
Rutile-type titanium oxide (TiO2) is a resource-rich and inexpensive material with a one-dimensional ion-diffusion path along the c-axis. However, it has received no attention as an anode material for Na-ion batteries because of its low el…
View article: Effect of Sn Addition on Anode Properties of SiO<i><sub>x</sub></i> in Sodium-Ion Batteries
Effect of Sn Addition on Anode Properties of SiO<i><sub>x</sub></i> in Sodium-Ion Batteries Open
Our group has investigated the properties of lithium-ion battery anodes fabricated using Sn/SiOx (SiOx is a mixed phase of Si clusters and amorphous SiO2 matrix). The addition of Sn improves the conductivity of the SiO2 matrix, while the f…
View article: Electrochemical Polarization Part 1: Fundamentals and Corrosion
Electrochemical Polarization Part 1: Fundamentals and Corrosion Open
Polarization measurement is one of the major electrochemical methods used by electrochemists. The changes in current/potential with time at constant potential/current are investigated. The outcomes of these observations can be used to plot…
View article: Electrochemical Polarization Part 2: Electrochemical Devices
Electrochemical Polarization Part 2: Electrochemical Devices Open
In this paper, examples of polarization measurements with a battery, electric double-layer capacitor, and fuel cell are discussed. The analysis of the polarization of a real cell and analytical methodology are described. In battery section…
View article: Effect of Sn Addition on the Anode Properties of SiO<i><sub>x</sub></i> for Lithium-Ion Batteries
Effect of Sn Addition on the Anode Properties of SiO<i><sub>x</sub></i> for Lithium-Ion Batteries Open
In this study, we have prepared Sn-added SiOx using a mechanical milling method and investigated the effect of Sn addition on the anode properties of SiOx for lithium-ion batteries. A charge–discharge cycle test with a charge limit of 1000…
View article: Impact of Low Temperatures on the Lithiation and Delithiation Properties of Si-Based Electrodes in Ionic Liquid Electrolytes
Impact of Low Temperatures on the Lithiation and Delithiation Properties of Si-Based Electrodes in Ionic Liquid Electrolytes Open
Lithium-ion batteries are used in various extreme environments, such as cold regions and outer space; thus, improvements in energy density, safety, and cycle life in these environments are urgently required. We investigated changes in the …
View article: Effects of Phase Change and Cu Doping on the Li Storage Properties of Rutile TiO<sub>2</sub>
Effects of Phase Change and Cu Doping on the Li Storage Properties of Rutile TiO<sub>2</sub> Open
The crystal structure and Li storage properties of Cu-doped rutile TiO2 after a phase change caused by lithiation were investigated for the first time. Structural analysis results confirmed that undoped rutile TiO2 was transformed to a dis…
View article: Improved Cycling Performance of Cr<sub>x</sub>V<sub>1−x</sub>Si<sub>2</sub>/Si Composite Electrode for Application to Lithium-Ion Battery Anodes
Improved Cycling Performance of Cr<sub>x</sub>V<sub>1−x</sub>Si<sub>2</sub>/Si Composite Electrode for Application to Lithium-Ion Battery Anodes Open
We have evaluated the anode properties of the silicide/Si composite electrodes for lithium-ion batteries and revealed that ternary silicide made by elemental substitution improved the electrochemical performance of the electrodes. In parti…
View article: Impact of the crystalline phase of binary silicide on its lithiation and delithiation properties
Impact of the crystalline phase of binary silicide on its lithiation and delithiation properties Open
The reversible capacity is not dependent on the amount of Si included in the silicide; the capacity was found to be independent on the composition of silicide even in the case of a given transition metal making up the silicide.
View article: Improvement of the Anode Properties of Lithium-Ion Batteries for SiO<i><sub>x</sub></i> with a Third Element
Improvement of the Anode Properties of Lithium-Ion Batteries for SiO<i><sub>x</sub></i> with a Third Element Open
Silicon oxide (SiO x ) has been placed into practical use as an anode active material for next-generation Li-ion batteries because it has a higher theoretical capacity than graphite anodes. However, the synthesis method is typically vapor …
View article: Systematic studies of rubidium-exposed surfaces by X-ray photoelectron spectroscopy and light-induced atom desorption
Systematic studies of rubidium-exposed surfaces by X-ray photoelectron spectroscopy and light-induced atom desorption Open
We systematically investigated various types of surfaces on which rubidium (Rb) atoms were deposited by X-ray photoelectron spectroscopy (XPS) and measured the light-induced atom desorption (LIAD) from those surfaces. The main surfaces of …
View article: Anode Properties of Cr<sub><i>x</i></sub>V<sub>1–<i>x</i></sub>Si<sub>2</sub>/Si Composite Electrodes for Lithium-Ion Batteries
Anode Properties of Cr<sub><i>x</i></sub>V<sub>1–<i>x</i></sub>Si<sub>2</sub>/Si Composite Electrodes for Lithium-Ion Batteries Open
We have reported the effects of substituting a transition metal in silicide on the electrochemical performance of the silicide/Si composite anode for lithium-ion batteries (LIBs); the Cr0.5V0.5Si2/Si electrode exhibited much better cyclabi…
View article: Electrochemical Lithiation and Delithiation Properties of FeSi<sub>2</sub>/Si Composite Electrodes in Ionic-Liquid Electrolytes
Electrochemical Lithiation and Delithiation Properties of FeSi<sub>2</sub>/Si Composite Electrodes in Ionic-Liquid Electrolytes Open
We investigated the applicability of ionic-liquid electrolytes to FeSi2/Si composite electrode for lithium-ion batteries. In conventional organic-liquid electrolytes, a discharge capacity of the electrode rapidly faded. In contrast, the el…
View article: Reaction Behavior of a Silicide Electrode with Lithium in an Ionic-Liquid Electrolyte
Reaction Behavior of a Silicide Electrode with Lithium in an Ionic-Liquid Electrolyte Open
Silicides are attractive novel active materials for use in the negative-electrodes of next-generation lithium-ion batteries that use certain ionic-liquid electrolytes; however, the reaction mechanism of the above combination is yet to be c…
View article: Indium-Doped Rutile Titanium Oxide with Reduced Particle Length and Its Sodium Storage Properties
Indium-Doped Rutile Titanium Oxide with Reduced Particle Length and Its Sodium Storage Properties Open
We hydrothermally synthesized In-doped rutile TiO2 particles in an anionic surfactant solution and investigated the influences of In doping and the particle morphology on the Na+ storage properties. The solid solubility limit was found to …