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 α-Co(OH)₂ and Ag, which drives the spontaneous deposition of Ag ions onto the defect-rich α-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 (R_transfer). The α-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 α-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 α-Co(OH)₂Ag90@CP600 as a promising supercapacitor electrode material, offering an effective pathway for developing high-performance electrode materials.