Electrodeposition-constructed 3D interconnected NiCoP4O12/MgCo2O4 conductive network for high-performance supercapacitors

Abstract

Nickel-cobalt phosphate (NCP) readily suffers from severe nanoparticle agglomeration during synthesis, leading to non-uniform dispersion and degraded electrochemical performance; moreover, NCP generally exhibits poor cycling stability. To overcome these limitations, we designed a self-supported three-dimensional (3D) heterostructured electrode of NiCoP₄O₁₂/MgCo₂O₄ (NCP/MCO) on Ni foam (NF). One-dimensional MCO nanowire arrays were first grown in situ as a robust, high-surface-area scaffold, followed by the uniform electrodeposition of zero-dimensional NCP nanoparticles to form a tightly integrated 3D network. The 3D network structure provides continuous electron-transport pathways, while the intimate contact at the NCP/MCO heterointerface further reduces charge-transfer resistance and facilitates ion diffusion, synergistically accelerating Faradaic kinetics and enhancing durability. This hierarchical architecture suppresses particle aggregation, shortens ion/electron diffusion paths, and improves structural integrity and charge-transport efficiency. As a result, the NCP/MCO/NF electrode delivers a high specific capacity of 273.74 mAh g⁻¹ at 1 A g⁻¹ and 210.5 mAh g⁻¹ at 20 A g⁻¹, while retaining 88.29 % of its capacity after 8000 cycles. The assembled NCP/MCO/NF//AC hybrid supercapacitor achieves an energy density of 51.46 Wh kg⁻¹ at a power density of 800 W kg⁻¹ and maintains 81.28 % of its initial capacity after 16,000 cycles. This work highlights a practical strategy for engineering interfacial contact and 3D architectures to realize high-rate, long-life supercapacitors.