Nagoya University · Engineering
Professor Takayuki Yamamoto's research lab specializes in the development and characterization of advanced solid electrolytes and oxide interfaces for next-generation energy storage devices, particularly all-solid-state batteries (ASSBs). The lab focuses on lithium-based anti-perovskites, oxyhalide electrolytes, and complex oxide heterostructures, with an emphasis on understanding and manipulating interfacial chemistry, ionic conductivity, and electrochemical stability. Key research directions include the synthesis of novel solid electrolytes via mechanochemical and thin-film processes, the control of crystal structure and doping effects to enhance Li+ mobility, and the design of stable, high-performance thin-film all-solid-state batteries. The lab combines advanced spectroscopic and diffraction techniques (e.g., XPS, XAS, synchrotron XRD) with electrochemical evaluation to bridge materials synthesis with device performance.
Figures are computed from collected data and may differ slightly.
The authors have investigated the chemical states at the interface of metal/perovskite oxides both with and without bipolar resistive switching (RS) behavior using photoemission spectroscopy and x-ray absorption spectroscopy. Al/Pr0.7Ca0.3MnO3 (PCMO), Al/La0.7Ca0.3MnO3 (LCMO), and Al/La0.33Sr0.67FeO3 interfaces were chosen as typical examples of interfaces for the perovskite-based resistance random access memory (ReRAM), while Pt/PCMO and Ag/LCMO were chosen as references for the metal/perovskit
Lithium-rich antiperovskites (Li3–xOHxX (X = Cl, Br)) are considered as promising electrolyte candidates for all-solid-state lithium secondary batteries with Li metal as the negative electrode owing to their soft nature and similarity to sulfide-based solid electrolytes. However, it has been reported that all-solid-state batteries with Li3–xOHxX exhibit low cycling stability. Although the reasons for this are not fully understood, one possibility could be the electrochemical instability of Li3–x
Lithium metal is a potential anode material to develop all-solid-state battery (SSB) with high energy density. However, Li metal easily reacts with atmospheric component (H2O, CO2, O2, N2) and then Li metal must be treated sensitively for industrial applications. Here, we report an inverted-stack Li-free thin-film SSB, SUS/Pt/LiPON/LiCoO2/Au, where highly-crystalline LiCoO2 thin film is formed on amorphous LiPON thin film at room temperature by aerosol deposition and Li metal is electrochemicall
The oxyhalide-based solid electrolyte Li<sub>2</sub>OHCl usually forms the thermodynamically stable orthorhombic phase at room temperature and shows poor lithium ionic conductivity. Above 35 °C, a structural phase transition into the cubic phase occurs and ionic conductivity is enhanced. In this work, mechanochemical synthesis of Li<sub>2</sub>OHCl is reported. The as-prepared Li<sub>2</sub>OHCl formed a cubic <i>Pm</i>3̅<i>m</i> structure and showed an ionic conductivity of 2.6 × 10<sup>-6</sup
We report that mixed-halogen anti-perovskite-type Li2OHBr1−xXx (X = Cl, I and x = 0–1) materials are prepared by room temperature ball-milling process, and investigate how the halogen mixing affects the total Li+ conductivity. Both solid solution ranges and lattice constants depend on the species of X. Among them, though X = I compounds form solid solution in narrow range of x smaller than 0.15, Li2OHBr0.9I0.1 shows the largest lattice constant and the highest total ionic conductivity at 25 °C (
This paper describes about the effect of Li-H exchange amount on total lithium-ion (Li<sup>+</sup>) conductivity of Li<sub>2+<i>x</i></sub>OH<sub>1-<i>x</i></sub>Br (<i>x</i> = -0.5 to +0.4). These samples are systematically prepared at room temperature by a dry ball-milling process using LiOH, LiOH·H<sub>2</sub>O, Li<sub>2</sub>O, and LiBr as starting materials. Synchrotron X-ray diffraction analysis reveals that single-phase Li<sub>2+<i>x</i></sub>OH<sub>1-<i>x</i></sub>Br samples are formed w
Oxide-based all-solid-state batteries (OX-SSBs) have been expected as next generation rechargeable batteries. In the OX-SSBs, charge transfer reaction occurs at electrode-solid electrolyte interface and then both of them must adhere well with smaller interfacial ion transfer resistance. Although various kinds of electrodes and solid electrolytes have been proposed, most of them are composed of different elements and concentrations, and, in addition, they have different thermal stability. Thus, s
Abstract Effects of target-substrate (TS) distance during pulsed laser deposition process on the chemical structure and lithium-ion conductivity of amorphous lithium phosphate (LPO) thin films are investigated. The shorter TS distance results in lower Li concentration, longer phosphate chain, and higher ionic conductivity. The ionic conductivity of 2.7 × 10−7 S/cm is obtained at 25 °C in the LPO thin film with short TS distance.
A method of simulating the transient response of semiconductor diodes with deep impurity levels has been established. This has enabled us to visualize the space charge overlapping model of switching when carriers are sufficiently injected and carrier-capture time is shorter than transit time. The results confirmed this model. Delay time in this case is dominated by the carrier transit time through the diode. In the case of shorter transit time, the rate of carrier supply by injection is the domi
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