Exploring the potential of constructing a hybrid supercapacitor with FeCoNi-LDH porous material containing oxygen vacancies for high-performance energy storage applications

A significant challenge in developing high-performance hybrid supercapacitors (HSCs) is the need to reasonably construct advanced architectures that consist of various components and exhibit superior electrochemical capacitance performance. The FeCoNi-layered double hydroxide (FeCoNi-LDH) porous material has a specific capacitance of 1960 F·g⁻¹ when used as the anode material at 1 A·g⁻¹. The FeCoNi-LDH material exhibits nanoplates with a distinct spindle morphology on their surface. Due to the combined action of the three metals and abundant oxygen vacancies, they exhibit unique rate performance and cycle stability. The electronic structure of LDH and the regulation of oxygen vacancy were confirmed by density functional theory (DFT) calculations. This suggests that the strength of hydroxide can reduce the energy required for oxygen vacancy formation in FeCoNi-LDH nanosheets and enhance ion and charge transfer, as well as electrolyte adsorption on the electrode surface. The FeCoNi-LDH//activated carbon (AC) HSC has an energy density of 53.2 Wh·kg⁻¹ at a power density of 800 W·kg⁻¹, surpassing other devices composed of comparable materials during the same timeframe. This study made significant advances in the design and synthesis of a ternary LDH porous structure with distinct oxygen vacancies, as well as its potential application in electrochemical energy storage.