Cobalt-doping in hierarchical NiS nanorod arrays enables high areal capacitance

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 8; no. 26; pp. 13114 - 1312
• Main Authors: Chen, Qiang, Jin, Jialun, Kou, Zongkui, Jiang, Jiangmin, Fu, Yulu, Liu, Ziang, Zhou, Liang, Mai, Liqiang
• Format: Journal Article
• Language: English
• Published: 07.07.2020
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d0ta04483k

Areal capacitance is an important metrics for miniaturized capacitive energy storage devices due to the constraint of device area. In the present work, we proposed a free-standing hierarchical cobalt-doped Ni 3 S 2 (Co-Ni 3 S 2 ) nanorod arrays as a novel pseudocapacitive electrode to realize impressively high areal capacitance. With enhanced surface area donated by the introduction of cobalt, the Co-Ni 3 S 2 nanorods exhibit an ultrahigh areal capacitance of 3.46 F cm −2 at 8 mA cm −2 , which is more than three-fold over that of pristine Ni 3 S 2 . When coupled with an FeOOH anode, the fabricated Co-Ni 3 S 2 //FeOOH hybrid supercapacitor can deliver a large areal capacitance of 1.61 F cm −2 , a peak energy density of 0.73 mW h cm −2 , and a peak power density of 36.00 mW cm −2 . Besides, the as-fabricated hybrid supercapacitor also exhibits stable capacitive performance (83.5% capacity retention after 5000 cycles). The advanced and stable Co-Ni 3 S 2 electrode developed in this work is highly desirable for micro supercapacitor devices. Cobalt-doped Ni 3 S 2 nanorod arrays have been prepared via a hydrothermal method. As a free-standing electrode, the Co-Ni 3 S 2 demonstrates ultrahigh areal capacitance, affording the Co-Ni 3 S 2 //FeOOH hybrid supercapacitor a high energy density.