Heterojunction α-Co(OH)2/α-Ni(OH)2 nanorods arrays on Ni foam with high utilization rate and excellent structure stability for high-performance supercapacitor

• Published in: Scientific reports Vol. 9; no. 1; pp. 12727 - 12
• Main Authors: Zhou, Shaojie, Wei, Wutao, Zhang, Yingying, Cui, Shizhong, Chen, Weihua, Mi, Liwei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-09-2019; Nature Publishing Group
• Subjects: 639/301/357/1016; 639/301/357/1018; Anions; Capacitance; Crystal structure; Electrodes; Electron transport; Humanities and Social Sciences; multidisciplinary; Nickel; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-49138-5

The practical implementation of supercapacitors is hindered by low utilization and poor structural stability of electrode materials. Herein, to surmount these critical challenges, a three-dimensional hierarchical α-Co(OH)
2
/α-Ni(OH)
2
heterojunction nanorods are built
in situ
on Ni foam through a mild two-step growth reaction. The unique lamellar crystal structure and abundant intercalated anions of α-M(OH)
2
(M = Co or Ni) and the ideal electronic conductivity of α-Co(OH)
2
construct numerous cross-linked ion and electron transport paths in heterojunction nanorods. The deformation stresses exerted by α-Co(OH)
2
and α-Ni(OH)
2
on each other guarantee the excellent structural stability of this heterojunction nanorods. Using nickel foam with a three-dimensional network conductive framework as the template ensures the rapidly transfer of electrons between this heterojunction nanorods and current collector. Three-dimensional hierarchical structure of α-Co(OH)
2
/α-Ni(OH)
2
heterojunction nanorods provides a large liquid interface area. These result together in the high utilization rate and excellent structure stability of the α-Co(OH)
2
/α-Ni(OH)
2
heterojunction nanorods. And the capacitance retention rate is up to 93.4% at 1 A g
−1
from three-electrode system to two-electrode system. The α-Co(OH)
2
/α-Ni(OH)
2
//AC device also present a long cycle life (the capacitance retention rate is 123.6% at 5 A g
−1
for 10000 cycles), a high specific capacitance (207.2 F g
−1
at 1 A g
−1
), and high energy density and power density (72.6 Wh kg
−1
at 196.4 W kg
−1
and 40.9 Wh kg
−1
at 3491.8 W kg
−1
), exhibiting a fascinating potential for supercapacitor in large-scale applications.