Interface engineering boosting the capacitive performance by constructing amorphous/crystalline NiCo-LDH@CoP@NiCo–P heterostructure

Abstract

The nickel-cobalt layered double hydroxide (NiCo-LDH) with high theoretical capacitance has great application potential as supercapacitor (SC) electrodes. Nevertheless, poor conductivity, low stability, and aggregation propensity have been considered as its major drawbacks. In this study, we have successfully constructed the amorphous/crystalline NiCo-LDH@CoP@NiCo–P heterogeneous interface composites by introducing two phosphate shells to improve the electrochemical properties. The combination of NiCo–P's high rate performance with the high capacitive performance provided by the CoP coating addresses the issue of insufficient conductivity of the original NiCo-LDH, resulting in composite electrodes with excellent electrochemical performance. At the current density of 1 A g, the specific capacitance is 1652.8 F g, and the rate performance is 70.8 % when the current increases to 20 times. The capacitance retention is 87.5 % after 5000 cycles at 30 A g. The asymmetric supercapacitor prepared with AC as the anode electrode shows a high specific capacitance of 118 F g in the water-based electrolyte system, with a capacitance retention of 60.1 % after 10,000 cycles at 10 A g. Furthermore, at a power density of 800 W kg, it exhibites a maximum energy density of 42 Wh kg. This study has demonstrated the enormous potential of interface design of heterostructures for supercapacitors.