Boosting ion diffusion at Ni2P@3D nanostructure carbon network interface for superior and durable sodium-ion hybrid capacitor

•Facile synthesis of Ni2P@CNF composite via one-step electrospinning method.•3D carbon nanofiber network offered enhanced Na+ ion diffusivity.•Ni2P@CNF demonstrated improved cycle stability (80%) than bare Ni2P (46%).•Na-ion hybrid capacitor was fabricated and demonstrated with improved performance.•High energy (136 Wh kg−1) and power (16.3 kW kg−1) density was achieved.