In-situ generated NiCo2O4/CoP polyhedron with rich oxygen vacancies interpenetrating by P-doped carbon nanotubes for high performance supercapacitors

In situ controllable preparation of P-doped carbon nanotubes intercalating NiCo2O4/CoP core–shell polyhedron film with rich oxygen vacancies shows an ultra-high volumetric/gravimetric energy density in hybrid supercapacitor. [Display omitted] •P-doped carbon nanotubes intercalated with NiCo2O4/CoP core–shell polyhedron film is successfully prepared.•The self-supporting film displays a maximum gravimetric/volumetric capacitance of 1918.4 F g−1/1074.3 F cm−3.•The electrode with rich oxygen vacancies shows enhanced conductivity and interconnected architecture.•The supercapacitor delivers an ultra-high gravimetric/volumetric energy density of 68.6 W h kg−1/41.8 W L−1. Supercapacitor with high storage capacity and small volumes are the development trends of miniaturization and portable energy storage systems. Herein, we design a novel self-supporting P-doped carbon nanotube (P-CNT) intercalating NiCo2O4/CoP core–shell polyhedron film. P-CNT is an ideal substrate with high electrical conductivity and interconnected porous architecture, which can enable the electrons transport to an external circuit from the electroactive component. NiCo2O4/CoP core–shell fluffy polyhedrons are derived from metal-organic frameworks with rich oxygen vacancies and abundant characteristics of pseudocapacitance, as well as better wettability. The self-supporting composite film readily achieves an ultra-high gravimetric and volumetric capacitance of 1918.4 F g−1 and 1074.3 F cm−3 at 1 A g−1. Accordingly, as-assembled hybrid supercapacitors using two binder-free electrodes, i.e., a self-supporting composite film as the positive electrode and P-doped CNT integrating graphene film as the negative electrode, harvest a remarkable gravimetric/volumetric energy density of 68.6 W h kg−1 (41.8 W h L−1) at 800 W kg−1 (488 W L−1). Our work suggests that the rational-designed NiCo2O4/CoP@P-CNTs electrode is a competitive candidate for designing next-generation supercapacitors with high volumetric energy density.