Constructing a NiCoO/NiCoP Heterostructure with a Built-In Electric Field for High-Performance Supercapacitors

Constructing heterostructures is a powerful way to improve the performance of electrode materials for supercapacitors. Herein, a compact NiCoO₂/NiCoP heterostructure (NiCoO/P) with a 3D porous network architecture was prepared via simple electrodeposition followed by an in situ phosphorization strategy. The strong built-in electric field at the heterointerface, coupled with the synergistic effects of NiCoO₂ and NiCoP, could endow abundant active sites, improve the charge transmission and OH^- absorption, and significantly enhancing electrochemical performance. Thanks to the unique 3D network structure and the synergy of the two components, the optimal NiCoO/P₅ achieved a high specific charge (1265.6 C g^-1) at 1.0 A g^-1 and a stable cycling lifetime with 82.3% capacity retention after 5000 cycles. Moreover, the hybrid supercapacitor using NiCoO/P₅ as a positive electrode delivered a satisfactory energy density of 54.9 Wh kg^-1 at 800 W kg^-1 and a desirable long-term cycling lifetime. This work provides a reference for designing and synthesizing well-defined electrode materials for the energy storage field.