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

• The Ag was spontaneously deposited on the defect-rich α-Co(OH) 2 layer as a supercapacitor electrode. • The Ag deposition acted on the electrons located in the d orbital of Co to improve capacitive ability and rate performance. • The α-Co(OH) 2 Ag90@CP600 exhibited a specific capacitance of 801F g −1 at 1 A g −1 and a rate performance of 57 % at 100 A g −1 . • The assembled ASC device by α-Co(OH) 2 Ag90@CP600 and AgNP@HWGN reached 1.8 V and retained high energy and power density. 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) 2 Ag90@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) 2 Ag90@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) 2 Ag90@CP600 as a promising supercapacitor electrode material, offering an effective pathway for developing high-performance electrode materials.