Nanodot BaTiO 3 supported LiCoO 2 cathode thin films can dramatically improve high-rate chargeability and cyclability. The prepared BaTiO 3 nanodot is <3 nm in height and 35 nm in diameter, and its coverage is <5%. Supported by high dielectric constant materials on the surface of cathode materials, Li ion (Li + ) can intercalate through robust Li paths around the triple-phase interface consisting of the dielectric, cathode, and electrolyte. The current concentration around the triple-phase interface is observed by the finite element method and is in good agreement with the experimental data. The interfacial resistance between the cathode and electrolyte with nanodot BaTiO 3 is smaller than that without nanodot BaTiO 3 . The decomposition of the organic solvent electrolyte can prevent the fabrication of a solid electrolyte interface around the triple-phase interface. Li + paths may be created at non solid electrolyte interface covered regions by the strong current concentration originating from high dielectric constant materials on the cathode. Robust Li + paths lead to excellent chargeability and cyclability.

Synthetic techniques to prepare large-size, flexible, and high-quality singlecrystalline sheets of transition metal oxides are crucial to developing lowenergy consumption devices. One promising way is a lift-off and transfer technique using a heterostructure of polymer supporting oxide and Sr 3 Al 2 O 6 (SAO) layers grown on a single-crystalline substrate. By removing the water-soluble SAO and the supporting layers, the oxide sheet is obtained. Although some ferroelectric flexible sheets are prepared by this method, a simpler method for obtaining large-size sheets is required. Herein, a lift-off and transfer method is proposed without a supporting layer. With this simple method, single-crystalline SrRuO 3 and BaTiO 3 flexible sheets with a lateral size of a few millimeters are successfully prepared. The SrRuO 3 sheet exhibits high crystallinity and conductivity. Meanwhile, the ferroelectricity of the BaTiO 3 sheet is successfully observed via polarization hysteresis loop measurements. In addition to the simplicity, this method has low costs and the substrate is reusable. Accordingly, the proposed method could enhance the development of various kinds of large-size functional oxide sheets.

Light irradiation onto a semiconductor generates heat; however, its electronic structure under high temperature has not yet been well investigated. In this study, we have carefully examined the temperature dependence on the bandgap of simple metal oxides, which are well-known photocatalysts, i.e., TiO2, CeO2, Nb2O5, SnO2 Ta2O5, WO3, ZnO, and ZrO2, using operando UV–visible spectroscopy under controlled temperature (from room temperature to 500 °C). Consequently, a linear decrease in bandgap was seen as a function of temperature with a different slope for each semiconductor. We found that the slope was dependent on the bonding distance between metal and oxygen. This finding is essential to develop a photocatalyst used under the condition involving photo-thermal effect.

On‐board vehicle applications dictate the need for improved low‐temperature power densities of rechargeable batteries. Integration of high‐permittivity artificial dielectric solid electrolyte interfaces (SEIs) into the lithium ion battery architecture is a promising path to satisfy this need. The relationship between the permittivity of various artificial dielectric SEIs and the resulting high‐rate capability at low temperatures is investigated. Room‐temperature studies reveal a weak relationship between these variables. However, at low temperatures, the correlation between the larger permittivity of the dielectric SEIs and the greater high‐rate capabilities of the cells is striking. The high‐rate capabilities for pulsed laser deposition‐synthesized cathode thin films with various BaTiO3 (BTO) SEIs covering configurations are evaluated. A remarkable improvement in the high‐rate capability is observed for LiCoO2 (LCO) modified with dot BTOs, while the rate capability for planar BTO (fully covered LCO) is weakened significantly. A series of experimental results prove that a large polarization, P, in the dielectric SEIs intensified with permittivity accelerates interfacial charge transfer near the dielectrics–LCO–electrolyte triple junction.

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