Heterointerface-engineered 2D/2D layered heterojunction with electronic coupling for energy storage

Co(OH)2 layers were grown on nickel foam by an instantaneous nucleation mechanism regulated by cathodic electrodeposition. Treating Co(OH)2 layers as the template, Ni(OH)2 layers were cladded onto to form Co(OH)2/ Ni(OH)2 heterojunction. The resultant self-supported binder-free architectures with abundant active sites and reduced aggregation facilitate faradaic redox reactions and shorten electron transport distance. The heterointerface-engineered Co(OH)2/Ni(OH)2 architecture with interfacial electronic coupling as electrodes highlighted its merits by delivering an areal capacity of 1965 mC cm- 2 at 1 mA cm- 2, a high specific capacity of 444 C g- 1, and a specific capacitance of 889 F g- 1 at 1 A g- 1. Moreover, the electrode demonstrated its chemical stability and structural endurance, with an 89.5 % retention of specific capacity at the 5000 th cycle. Additionally, the hybrid device assembled with Co(OH)2/Ni(OH)2//activated carbon composition delivered a specific capacity of 181 C g- 1 at 1 A g- 1, a maximum specific energy of 53.1 Wh kg- 1 at 1 A g- 1, and an appreciable specific power of 16.56 kW kg- 1 at 20 A g- 1. The proposed strategy takes advantage of yielding replicated twodimensional sheets (2D) with interfacial electronic coupling, ample active sites, and high synergy between the two layers, which help in designing high-energy electrochemical storage devices.