Facile synthesis of porous high-entropy perovskite nanoparticles through MOF gel method for solid-state supercapacitor application

High-entropy oxides (HEOs) are regarded as promising candidates for supercapacitors owing to their distinctive chemical composition and unique mixture characteristics. However, conventional methods still pose challenges in synthesizing HEOs with a desirable specific surface area and a favorable pore structure because most of the traditional synthesis templates are compact and impermeable. Herein, a MOF (metal–organic framework) gel method was developed to synthesize La(Mn_0.2Fe_0.2Co_0.2Ni_0.2Cu_0.2)O₃ high-entropy oxide with a high specific surface area and abundant mesopores. The experimental data showed that the mole ratio of metal cations/ligands significantly influenced the specific surface area of HEO, and the product obtained at the optimal mole ratio exhibited an outstanding specific surface area of approximately 43.2 m² g⁻¹. When utilized as supercapacitor electrodes, the optimal HEO nanoparticle exhibited exceptional electrochemical properties, including rapid kinetics, low impedance, excellent stability, and a superior capacitance of 609.3F g⁻¹ (243.7C g⁻¹). Furthermore, a solid-state asymmetric supercapacitor device was assembled using HEO//activated carbon, which achieved a high specific capacitance of 106.8F g⁻¹ (154.9C g⁻¹) at 1 A g⁻¹. Additionally, it showed a superior energy density of 31.2 W h kg⁻¹ and a high power density of 14500 W kg⁻¹ with a capacitance retention of 84.2 % after 10,000 cycles. This study presents a simple and efficient approach for synthesizing porous high-entropy materials for supercapacitors.