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.
Keywords: Core-shell polyhedron; Energy density; Oxygen vacancies; Self-supporting electrode; Supercapacitor.
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