Electrochemical performance of all-solid-state asymmetric supercapacitors based on Cu/Ni-Co(OH)2/Co4S3 self-supported electrodes

Understanding the performance contributions by rational designing of electrode structure holds the key point in the construction of supercapacitors. Here, a facile in suit hydrothermal method which integrates morphology modulation and charge transfer acceleration has been developed to synthesize self-supported Cu/Ni-Co(OH)2/ Co4S3 electrode on Ni foam. The copper layer can significantly contribute to the electron transportation ability of the whole materials. Not only the merit mentioned above but also the synergistic effect between Co(OH)2 and Co4S3 makes low resistance in electrons and ions transportation possible, therefore, resulting in largely improved electrochemical performance. Meanwhile, we can rational regulate the morphology of Cu/Ni-Co(OH)2/Co4S3 just by changing the relative amount of urea. Apart from that, during the structure regulation process, we further explore the relationship between electrochemical properties and morphology changes. As a result, the obtained optimal Cu/Ni-Co(OH)2/Co4S3-0.6 possesses an outstanding specific capacitance of 966 C g-1 at 1 A g-1. In addition, an all-solid-state asymmetric Cu/Ni-Co(OH)2/Co4S3-0.6//AC supercapacitor device was fabricated, showing a prominent energy density of 64.2 Wh kg- 1 at 800 W kg -1. This work provides a new avenue for high performance electrode materials synthesis and explores the key point in the relationship between morphologies and electrochemical properties among electrode materials used in supercapacitors.