Phosphorus‐Doped Nickel Oxide Micro‐Supercapacitor: Unleashing the Power of Energy Storage for Miniaturized Electronic Devices

Abstract For an uninterrupted self‐powered network, the requirement of miniaturized energy storage device is of utmost importance. This study explores the potential utilization of phosphorus‐doped nickel oxide (P‐NiO) to design highly efficient durable micro‐supercapacitors. The introduction of P as a dopant serves to enhance the electrical conductivity of bare NiO, leading to 11‐fold augmentation in volumetric capacitance to 841.92 Fcm −3 followed by significant enhancement of energy and power density from 6.71 to 42.096 mWhcm −3 and 0.47 to 1.046 Wcm −3 , respectively. Theoretical calculations used to determine the adsorption energy of OH‐ ions, revealing higher in case of bare NiO (1.52 eV) as compared to phosphorus‐doped NiO (0.64 eV) leading to high electrochemical energy storage performance. The as‐designed micro‐supercapacitor (MSC) device demonstrates a facile integration with the photovoltaic system for renewable energy storage and smooth transfer to external loads for enlightening the blue LED for ≈1 min. The choice of P‐NiO/Ni not only contributes to cost reduction but also ensures minimal lattice mismatch at the interface facilitating high durability up to 15 K cycles along with capacitive retention of ≈100% and coulombic efficiency of 93%. Thus, the heterostructure unveils the possibilities of exploring miniaturized energy storage devices for portable electronics.