High-Performance Flexible All-Solid-State Asymmetric Supercapacitors Based on Vertically Aligned CuSe@Co(OH)2 Nanosheet Arrays

The developments of electrode active materials provide the opportunities for next-generation energy storage devices. The arrangement of electrode materials on the substrate has recently emerged as a promising strategy for preparing high-performance supercapacitors. Herein, we demonstrate a novel vertically aligned CuSe@Co­(OH)2 nanosheet arrays electrode for supercapacitor application. The materials are thoroughly characterized by structural and spectroscopic techniques. Electrochemical performance of CuSe@Co­(OH)2 nanosheet arrays are investigated in detail, which exhibit a specific capacitance as much as 1180 F g–1 at a current density of 1 A g–1. A flexible asymmetric all-solid-state supercapacitor is fabricated using CuSe@Co­(OH)2 nanosheet arrays as the positive electrode and activated carbon as the negative electrode. The device delivers a volumetric capacitance of 441.4 mF cm–3 with maximum energy density and maximum power density is 0.17 and 62.1 mW cm–3, as well as robust cycling stability (∼80.4% capacitance retention after 10 000 cycles), excellent flexibility, and mechanical stability. The excellent electrochemical performance can be attributed to its unique vertically aligned configuration.