Silver-incorporated NiCo metal–organic frameworks with controlled morphology for enhanced cycling in flexible supercapacitor applications

Abstract

Supercapacitors (SCs) are highly promising for next-generation energy-storage applications due to their predominant properties. Metal–organic frameworks (MOFs), an innovative class of energy storage electrodes, offer a wide range of structural variations and high porosities. However, their broad application is limited by their low capacitance and cycle stability. This study uses a facile solvothermal method to synthesize a series of NiCo-MOF (NCA_X-MOF/NF, X = 0, 5, 10, 15, and 20) on nickel foam (NF) with varying amounts of Ag⁺ cations. This study systematically explores the influence of Ag⁺ incorporation on the morphology and electrochemical performance of NiCo-MOF. Analysis of the MOF morphology reveals that the introduction of Ag⁺ transforms the bulk NiCo-MOF into a spherical structure. NCA₁₅-MOF/NF, with its uniform size and spherical morphology, exhibits the best electrochemical performance, achieving a specific capacitance of 1317 F g⁻¹ at 1 A g⁻¹ and retaining 89% of its capacitance after 15 000 cycles. Furthermore, upon assembly into a flexible symmetric supercapacitor, it delivers an energy density of 72.55 W h kg⁻¹ at a power density of 408.61 W kg⁻¹. This study suggests that incorporating Ag⁺ can tailor the MOF morphologies and improve their electrochemical characteristics, thus providing a novel approach for fabricating NiCo-MOF electrodes with enhanced SC performance.