Li‐Assisted Structural and Morphological Engineering of Ni–Co Phosphate Nanoarchitectures for High‐Performance Supercapacitors

The electrochemical properties of transition‐metal phosphates could be considerably improved through structural and morphological tuning. In this work, Li‐assisted Ni–Co phosphate (Li‐NCP) electrodes were grown directly onto nickel foam via a straightforward one‐pot hydrothermal technique, and the influence of Li ⁺ assistance on the structural, morphological, and electrochemical properties was studied in detail. Structural tuning and variations in the local coordination environments resulting from Li ⁺ ‐assisted hydrothermal synthesis were analyzed using XRD and FTIR spectroscopy. The morphological tuning of the electrode from stacked platelets to flower‐like structures made up of interconnected needle‐like nanostructures was observed by FESEM. Among all the electrodes fabricated in this study, the Li‐2 electrode showed exceptional electrochemical performance, with areal capacitances of 10,828 mF cm ⁻² at 3 mA cm ⁻² and 4144 mF cm ⁻² at 20 mA cm ⁻² . The charge‐transfer resistance determined by EIS was extremely low (0.0571 Ω), indicating superior charge‐transfer kinetics. The optimized electrode retains 70% of its capacitance after 5000 cycles. A hybrid Li‐2//graphite solid‐state supercapacitor worked stably within a 1.2 V potential window, and two devices in series successfully powered a red LED, demonstrating the practical potential of the developed electrode for advanced energy storage applications.