NiSe2/Ni(OH)2 Heterojunction Composite through Epitaxial-like Strategy as High-Rate Battery-Type Electrode Material

Highlights A facile and effective epitaxial-like growth strategy is applied to fabricate the NiSe 2 /Ni(OH) 2 heterojunction composite. The assembled asymmetric supercapacitor based on the heterojunction composite surpasses most of the reported results. It is the first time that the powdered electrode materials can have such large capacity, high rate, and extreme long cycle life. Constructing heterojunction is a promising way to improve the charge transfer efficiency and can thus promote the electrochemical properties. Herein, a facile and effective epitaxial-like growth strategy is applied to NiSe 2 nano-octahedra to fabricate the NiSe 2 -(100)/Ni(OH) 2 -(110) heterojunction. The heterojunction composite and Ni(OH) 2 (performing high electrochemical activity) is ideal high-rate battery-type supercapacitor electrode. The NiSe 2 /Ni(OH) 2 electrode exhibits a high specific capacity of 909 C g −1 at 1 A g −1 and 597 C g −1 at 20 A g −1 . The assembled asymmetric supercapacitor composed of the NiSe 2 /Ni(OH) 2 cathode and p-phenylenediamine-functional reduced graphene oxide anode achieves an ultrahigh specific capacity of 303 C g −1 at 1 A g −1 and a superior energy density of 76.1 Wh kg −1 at 906 W kg −1 , as well as an outstanding cycling stability of 82% retention for 8000 cycles at 10 A g −1 . To the best of our knowledge, this is the first example of NiSe 2 /Ni(OH) 2 heterojunction exhibiting such remarkable supercapacitor performance. This work not only provides a promising candidate for next-generation energy storage device but also offers a possible universal strategy to fabricate metal selenides/metal hydroxides heterojunctions.