Hierarchical NiGa-LDH/Ti₃C₂T_x MXene composites for enhanced capacitance in alkaline all-solid-state energy storage

In recent years, the rapid advancement of safe energy storage devices with high energy and power densities has generated significant interest in all-solid-state supercapacitors (SCs). MXene-based nanomaterials have emerged as promising candidates for energy storage owing to their exceptional redox properties, extensive surface area, and high metallic conductivity. Additionally, layered double hydroxides (LDHs), distinguished by their distinct nanostructures, and efficient ion channels, with elevated specific capacitance, have attracted interest. Consequently, a novel all-solid-state supercapacitor(AASCs) was fabricated by employing a hydrothermal method to integrate NiGa-LDH nanosheets with Ti₃C₂T_x MXene, resulting in enhanced energy storage properties. The NiGa-LDH/Ti₃C₂T_x MXene exhibits excellent properties, including a specific capacitance of 618.66 F g^-1 at 1 mA cm^-2 and 93.75 % capacitance retention after 5,000 cycles at 1 mA cm^-2. The all-solid-state NiGa-LDH/Ti₃C₂T_x MXene//activated carbon(AC) asymmetric supercapacitor (AASCs) demonstrates an impressive energy density of 20 Wh kg^-1 and a high power density of 400 W kg^-1. Density-functional theory (DFT) studies show that NiGa-LDH/Ti₃C₂T_x MXene has a high density of states (DOS) around the Fermi level and possesses a potassium ion adsorption energy of -2.36 eV. This study provides technical and theoretical insights into the design of intricate nanostructures utilizing MXene-based nanomaterials for all-solid-state energy storage device.