Terephthalate-based cobalt hydroxide: a new electrode material for supercapacitors with ultrahigh capacitance

• Published in: Dalton transactions : an international journal of inorganic chemistry 2018-10, Vol.47 (42), p.14958-14967
• Main Authors: Ou, Xiuling, Wang, Yifan, Lei, Shuijin, Zhou, Wei, Sun, Shunqiang, Fu, Qi, Xiao, Yanhe, Cheng, Baochang
• Format: Article
• Language: English
• Subjects: Activated carbon; Aqueous electrolytes; Cobalt; Crystal growth; Current density; Electrode materials; Electrodes; Flux density; Metal foams; Nickel; Scanning electron microscopy; Storage capacity; Supercapacitors; Terephthalate
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c8dt03231a

Searching for new electrode materials is one of the key tasks in developing high-performance supercapacitors. In this work, as a layered hydroxyl derivative, terephthalate-based cobalt hydroxide, Co 2 (OH) 2 (C 8 H 4 O 4 ), is successfully prepared in situ on nickel foam through a simple hydrothermal route. The scanning electron microscopy results reveal that the products are composed of massive double-blade lath crystals grown along the a -axis. The as-obtained Ni-foam-supported Co 2 (OH) 2 (C 8 H 4 O 4 ) is directly used as the positive electrode of supercapacitors without further treatment. The resulting Co 2 (OH) 2 (C 8 H 4 O 4 ) electrode exhibits ultrahigh charge storage capacity with the specific capacity of 9.36 C cm −2 (1261 C g −1 ) at a current density of 10 mA cm −2 (0.5 A g −1 ) and good cycling stability with the capacity retention of 82.4% over 5000 cycles at a current density of 50 mA cm −2 . In combination with activated carbon as the negative electrode in 3 M KOH aqueous electrolyte, the constructed asymmetric supercapacitor delivers a high energy density of 30.62 W h kg −1 at a power density of 221 W kg −1 within a voltage window of 1.5 V. These encouraging electrochemical performances enable the developed terephthalate-based cobalt hydroxide to be a promising electrode material for supercapacitor applications. Terephthalate-based cobalt hydroxide, a layered hydroxyl derivative, is grown on Ni foam and first applied in supercapacitors with ultrahigh capacitances.