Hierarchical NiO-In₂O₃ microflower (3D)/ nanorod (1D) hetero-architecture as a supercapattery electrode with excellent cyclic stability

Three-dimensional (3D) hybrid nanostructured electrodes based on one-dimensional (1D) nanorod arrays have recently attracted great attention owing to their synergistic effect of three-dimensional nanostructures and application in energy storage and conversion devices. Here, we designed a heterostructured supercapattery electrode from a combination of NiO and In₂O₃ with a hierarchical hybrid microstructure on nickel foam (NF). Simultaneous heterogeneous growth of 1D nanorod-supported 3D microflower structures on nickel foam enhanced the non-capacitive faradaic energy storage performance due to the synergistic contribution from hierarchical hybrid nanostructure. The heterostructured electrode exhibits a high specific capacity of 766.65 C g^-1 at 5 A g^-1 and remains as high as 285.12 C g^-1 at 30 A g^-1. The composite electrode shows an excellent rate performance as a sandwich type symmetric device, offering a high specific energy of 26.24 W h kg^-1 at a high power of 1752.8 W kg^-1. The device shows a long term cyclic stability with 79% retention after 50000 cycles, which is remarkable for an oxide based pseudocapacitor. These results suggest that NiO-In₂O₃ with hybrid micro/nano architecture could be a promising electrode for next generation supercapatteries.