P-doped NiMn-layered double hydroxides (LDHs) for the preparation and study of supercapacitor electrodes

Nickel-manganese layered double hydroxides (NiMn-LDHs) exhibit low intrinsic conductivity, nanosheet stacking, and insufficient structural stability, resulting in low energy density, which severely restricts their application in high-energy storage systems. The P-doped NiMn-LDHs (P-NiMn-LDHs) electrode with a 3D nanoflowers structure was prepared in situ on porous nickel foam (NF) through a one-step hydrothermal route. The present study systematically investigates the influences of P-doping on the morphology, crystal structure, electronic states, and electrochemical performance of NiMn-LDHs. The results indicate that P-doping maintains the layered framework while introducing lattice distortion, abundant defects, and loose porous ultrathin nanosheet assemblies, thereby increasing the specific surface area and electroactive sites. Electrochemical measurements demonstrate that the P-NiMn-LDHs electrode exhibits significantly higher specific capacitance and faster reaction kinetics compared to the undoped counterpart. It exhibits a capacity retention of 94.9% over 3,000 cycles at 1 A g-1, which is remarkably higher than the 88.9% of pristine NiMn-LDHs. This doping strategy has been demonstrated to enhance the specific surface area and active-site density, thus providing a novel framework for the design of advanced high-performance electrode materials.