Rational construction of multilayer NiCo-MOF@MnO2 heterostructures with optimized charge storage behavior for asymmetric supercapacitors

Abstract

Manganese dioxide (MnO₂) is a promising supercapacitor electrode material with its high theoretical capacitance, abundant resources, and eco-friendliness. However, poor ion transport and volume expansion during cycling hinder its practical performance. In contrast, metal–organic frameworks (MOFs) provide extensive surface area and structural versatility but suffer from low intrinsic conductivity, limiting their direct application as electrodes. Here, a MOF-derived NiCo-MOF@MnO₂ heterostructure is successfully anchored onto activated carbon cloth (AC) to prepare a self-supported electrode (NCM@MO-1) through a rational synthetic regulation strategy. The NCM@MO-1 electrode presents a unique overlapping massive nanostructure conducive to exposing more active sites and shortening the diffusion path of electrolyte ions. Owing to its optimized structure and composition, the NCM@MO-1 electrode exhibits improved specific capacitance of 15.2 F/cm² at 2 mA/cm² and ultrahigh rate performance of 65 % at 50 mA/cm². Moreover, the NCM@MO-1//annealed AC (AAC) asymmetric supercapacitor (ASC) achieves a superb energy density of 1.191 mWh/cm² at 1.715 mW/cm² and an exceptional cycle durability (about 85.67 % retention over 10,000 cycles). The meticulously prepared NCM@MO-1 electrode presents significant potential for diverse applications, especially in the realm of high-performance supercapacitors, where the material is poised to serve as a key enabler for next-generation devices.