Interface Engineering of a Ni ₂ P-LaPO ₄ Heterostructure for a High-Energy Asymmetric Hybrid Supercapacitor

Pioneering pathways to engineer advanced materials is a necessity for the development of robust energy storage devices. Herein, a soft-template hydrothermal approach was utilized for the preparation of Ni2P and LaPO4, followed by ultrasonication together to develop the NLP composite. The synergistic interaction, via the phosphide-phosphate interface, brings out the high redox property of Ni2P and the superior ionic stability of LaPO4 together in varying ratios to form NLP-1, NLP-2, and NLP-3. This results in intimate heterostructure contacts for faster reaction kinetics, resulting in enhanced electrochemical performance. NLP-1 composite exhibited superior performance among them, with a specific capacitance of 993 F/g at a current density of 1 A/g, retaining 93% of its initial capacitance after 10,000 cycles. NLP-1 was utilized as cathode material for the fabrication of a solid-state asymmetric supercapacitor device, with biomass-derived activated carbon as anode material. The fabricated device achieved a high energy density of 92.025 Wh/kg at a power density of 270 W/kg, retaining 90% performance after 10,000 consecutive cycles. The results confirm the robust nature of NLP composites, making them an ideal candidate for real-time device assembly.