Open Access Nano Express

Electric charging/discharging characteristics of super capacitor, using de-alloying and anodic oxidized Ti-Ni-Si amorphous alloy ribbons

Mikio Fukuhara123* and Kazuyuki Sugawara4

Author Affiliations

1 New Industry Creation Hatchery Center, Tohoku University, 3-4-1, Sakuragi, Tagajyo, Miyagi 985-8589, Japan

2 Fracture and Reliability Research Institute, Tohoku University, Sendai 980-8579, Japan

3 Green Device Laboratory, Institute for Nanoscience & Nanotechnology, Waseda University, Shinjuku, Tokyo 162-0041, Japan

4 Research Institute for Electromagnetic Materials, Sendai, Miyagi 982-0807, Japan

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Nanoscale Research Letters 2014, 9:253  doi:10.1186/1556-276X-9-253

Published: 21 May 2014

Abstract

Charging/discharging behaviors of de-alloyed and anodic oxidized Ti-Ni-Si amorphous alloy ribbons were measured as a function of current between 10 pA and 100 mA, using galvanostatic charge/discharging method. In sharp contrast to conventional electric double layer capacitor (EDLC), discharging behaviors for voltage under constant currents of 1, 10 and 100 mA after 1.8 ks charging at 100 mA show parabolic decrease, demonstrating direct electric storage without solvents. The supercapacitors, devices that store electric charge on their amorphous TiO2-x surfaces that contain many 70-nm sized cavities, show the Ragone plot which locates at lower energy density region near the 2nd cells, and RC constant of 800 s (at 1 mHz), which is 157,000 times larger than that (5 ms) in EDLC.

Keywords:
Electric storage devices; Amorphous alloys with TiO2-x surfaces; Nanometer sized cavity