Two-step synthesis of a-NiCu(OH)2CO3/Na3NiCuCO3PO4: a battery-type electrode for pseudocapacitor applications

Here, we report the environmentally friendly and cost-effective two-step synthesis of amorphous nickel-copper carbonate hydroxide on nickel-copper carbonophosphate (a-NiCu(OH)(2)CO3/Na3NiCuCO3PO4) using the alkaline (1 M KOH) etching of hydrothermally prepared Na3NiCuCO3PO4 at room temperature. The KOH etching creates a mesoporous structure, and the high specific surface area (171.14 m(2) g(-1)) assists electrolytes in passing through the porous architecture more efficiently and facilitates high faradaic reactions. The KOH etched sample with a Ni : Cu ratio of 4 : 1 in the precursor (Ni:Cu-80:20+KOH) exhibits excellent specific discharge capacitance of 3400.0 F g(-1) at a current density of 1 A g(-1). The assembled Ni:Cu-80:20+KOH based symmetric battery-type pseudocapacitor (with 1 mg mass loading) exhibits a maximum energy density of 32.4 W h kg(-1) at a power density of 1.54 kW kg(-1) with excellent cyclic stability (65% retention after 40 000 charge-discharge cycles at the current density of 5 A g(-1)). The symmetric supercapacitors (with 4 mg mass loading) connected in series can illuminate a red light-emitting diode (LED) for 18.16 min (two cells) and power a 6 V DC motor fan for 14 s (four cells). The features efficaciously illustrate that a-NiCu(OH)(2)CO3/Na3NiCuCO3PO4 is a promising electrode material for advance electronic applications.

Automated summary

In this study, environmentally friendly and cost-effective synthesis of amorphous nickel-copper carbonate hydroxide was achieved by etching hydrothermally prepared Na3NiCuCO3PO4 using alkaline solution. The resulting mesoporous structure and high specific surface area enhanced electrolyte penetration and facilitated high faradaic reactions. The synthesized material showed excellent capacitance and cyclic stability, making it a promising electrode material for advanced electronic applications.