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

Abstract

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