Oxygen-vacancy-enriched CuMn2O4@CoAl layered double hydroxide nickel foam serving as a sophisticated electrode material for asymmetric supercapacitors

Abstract

CuMnO, the abundant spinel in the earth, is considered a promising electrode material in the fields of energy storage and conversion, its practical application are hindered by limitations such as the insufficient energy density and poor stability of the material. Here, CuMnO@CoAl layered double hydroxide nickel foam (CuMnO@CoAl LDH NF) with abundant oxygen vacancy was constructed applied as an electrode material by simple hydrothermal method and NaBH reduction. The electrochemical tests validate that CuMnO@CoAl LDH NF soaked in NaBH solution stirring for 0.5 h (donated as CuMnO@CoAl LDH NF-0.5) shows a remarkable specific capacitance of 1437.7 F · g at the current density of 1.0 A · g. The capacitance retention remains 86.1 % even after enduring 5000 cycles at a higher current density of 8.0 A · g. Furthermore, the assembled CuMnO@CoAl LDH NF-0.5// activated carbon (AC) supercapacitor exhibits a capacitance of 167.5 F · g, achieving a maximum energy density of 52.44 Wh · kg and a power density of 4029.5 W · kg when operated at the current density of 1.0 A · g. The experimental results show that the prepared material has excellent conductivity, good chemical stability, remarkable specific capacitance, and stable cycle life as a supercapacitor electrode. All these results confirm that both the construction of CuMnO@CoAl LDH core-shell structure and the reduction of NaBH can introduce abundant oxygen vacancy defects in CuMnO@CoAl LDH NF, which can significantly improve the electrical conductivity and accelerate the redox kinetics.