High-Performance Supercapacitor with Faster Energy Storage and Long Cyclic Life Based on CuO@MnO2 Nano-Core–Shell Array on Carbon Fiber Surface

Abstract

Supercapacitors are a new type of energy storage device, receiving wide attention of researchers in recent years. The electrode material is the core part of the supercapacitor and therefore has higher research value. In this paper, we report an efficient preparation of electrode based on CuO@MnO2 core–shell nanoarray structure and supercapacitor with rapid charge and discharge and long cycle life. First, the surface of the carbon fiber (CF) is electrochemically deposited with a uniform layer of copper (Cu). Second, after in situ chemical treatment on the surface of the Cu layer, copper hydroxide (Cu(OH)2) nanofibers grow and then are converted into copper oxide (CuO) nanofibers. This is the first time that Cu(OH)2 nanofibers have been grown in situ on the surface of CF. Finally, a layer of MnO2 nanocoating grows in situ on the surface of CuO nanofibers to form the CuO@MnO2 core–shell structure. The supercapacitor exhibits excellent charge and discharge rates, taking 4.86 s at a current density of 7 A·g–1, and much shorter than other materials. In addition, it has good capacity retention (96.81%) after 5000 cycles and reaches a maximum energy density of 21.32 Wh·kg–1 at a power density of 7.20 kW·kg–1. Because the prepared electrode material based on the CuO@MnO2 core–shell structure has a faster charge and discharge rate, excellent cycle stability, and high energy density, it will have great application prospects in fields such as spherical triboelectric nanogenerator in the future.