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

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 alpha-Co(OH)(2)/alpha-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 alpha-M(OH)(2)(M =Co or Ni) and the ideal electronic conductivity of alpha-Co(OH)(2) construct numerous cross-linked ion and electron transport paths in heterojunction nanorods. The deformation stresses exerted by alpha-Co(OH)(2) and alpha-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 alpha-Co(OH)(2)/alpha-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 alpha-Co(OH)(2)/alpha-Ni(OH)(2) heterojunction nanorods. And the capacitance retention rate is up to 93.4% at 1Ag(-1) from three-electrode system to two-electrode system. The alpha-Co(OH)(2)/alpha-Ni(OH)(2)//AC device also present a long cycle life (the capacitance retention rate is 123.6% at 5Ag(-1) for 10000 cycles), a high specific capacitance (207.2 Fg(-1) at 1Ag(-1)), and high energy density and power density (72.6Wh kg(-1) at 196.4W kg(-1) and 40.9Wh kg(-1) at 3491.8W kg(-1)), exhibiting a fascinating potential for supercapacitor in large-scale applications.