Amorphous titanium-oxide supercapacitors with high capacitance

¹ New Industry Creation Hatchery Center, Tohoku University - Sendai 980-8579, Japan
² Fracture and Reliability Research Institute, Graduate School of Engineering, Tohoku University Sendai 980-8579, Japan
³ The Electron Microscopy Center, Tohoku University - Aoba, Sendai 980-8577, Japan

^(a) fukuhara@niche.tohoku.ac.jp

Received: 9 May 2019
Accepted: 19 December 2019

Abstract

An amorphous titanium-oxide film oxidized anodically on amorphous Ti–10at%V–15at%Si alloy ribbons demonstrated excellent electric properties. Specifically, it showed a remarkable increase in parallel capacitance Cp, series capacitance Cs, time constant RCs, and decrease in the dielectric loss with decreasing frequency. The oblate semicircle after a semicircle with a Warburg region in the Nyquist diagram and rapid increases in the real impedance in the low-frequency region in the Bode diagram demonstrated a parallel circuit comprising an electric transport resistance Re (0.64 MΩ), and a high electric double-layer capacitance C_dl (604.0 μF/cm ²) at a nanometer-sized ( in convex size) uneven surface between an upper (Ti_0.84V_0.11Si_0.05)O_1.655 layer approximately 45-nm deep and air. The superior capacitances could be elucidated by electrostatic induction of a large positive charge to the uneven oxide surface based on the electronic conduction state derived from TiO₂/VO₂ nanostructural interfaces in the upper oxide layer.