Spontaneous deposition of Ag nanoclusters on defect-rich α-Co(OH)2 for high-rate performance supercapacitor

Abstract

Enabling the rapid and convenient preparation of supercapacitor electrode materials with excellent rate performance and stability, this study utilizes the standard redox potential difference between alpha-Co(OH)2 and Ag, which drives the spontaneous deposition of Ag ions onto the defect-rich alpha-Co(OH)2 layer. The deposition of Ag nanoclusters is controlled by adjusting the reaction time. The results of Density functional theory (DFT) calculation reveal that Ag deposition interacts with electrons in the Co d-orbital, enhancing capacitive performance and anion transport rates (Rtransfer). The alpha-Co(OH)2Ag90@carbon paper (CP)600 exhibits a specific capacitance of 801 F g-1 at 1 A g-1 and a rate capability of 57 % at 100 A g-1, maintaining 85.7 % capacitance retention after 10,000 charge-discharge cycles at 100 A g-1. The alpha-Co(OH)2Ag90@CP600 as a cathode in an asymmetric supercapacitor (ASC) paired with an anode which using silver nanoparticles integrated with highly water-dispersible graphene nanosheets (AgNP@HWGN). The ASC device achieves an energy density of 35.1 Wh kg-1 at a power density of 900 W kg-1 (1.8 V) and demonstrates excellent cycling stability over 10,000 cycles under 20 A g-1. This approach highlights the potential of alpha-Co(OH)2Ag90@CP600 as a promising supercapacitor electrode material, offering an effective pathway for developing high-performance electrode materials.