A novel TiO2/CuSe based nanocomposite for high-voltage asymmetric supercapacitors

Abstract

TiO2/CuSe nanocomposites were synthesized using a straightforward wet chemical without any sophisticated template. A variety of characterization techniques, including XRD, Raman spectra, UV-Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and SEM/EDS analysis were used to elucidate the structure, morphology, and optical properties of the TiO2/CuSe nanocomposite. In addition, CV, GCD, and EIS were used to study the supercapacitive performance of the TiO2/CuSe based electrodes in detail. Three-electrode cells made of TiO2/CuSe with 0.56 g weight ratio of CuSe content (denoted as ZT-3) exhibited a maximum specific capacitance of around 184 F g−1, low Rs and Rct values (2.99 Ω/6.21 Ω) among samples investigated, facilitating the charge transport and efficient utilization of ion diffusions during the electrochemical activities. Based on the outstanding performance of the ZT-3 electrode, we further assembled an asymmetric supercapacitor (ASC) composed of ZT-3//AC and successfully expanded a voltage window (2.2 V) for the first time, which yielded a specific capacitance of 40.5 F g−1 at 1 A g−1. More importantly, the ASC exhibited a high specific energy of 27 Wh kg−1 and maintained 11.4 Wh kg−1 at a high specific power of 7125.5 W kg−1 even at a high current density of 20 A g−1 with excellent cycling stability (90% retention) after 20,000 cycles.

Keywords

• Titanium dioxide
• CuSe
• Supercapacitor
• ASC
• Electrochemical
• Specific energy and power