Physics

Nanotechnology

Electrode

Organic chemistry

Shell (structure)

Composite number

Astronomy

Engineering

Carbon fibers

Physical chemistry

Composite material

Core (optical fiber)

Chemistry

Materials science

Chemical engineering

Optoelectronics

Electrochemistry

Nitrogen

Doping

Supercapacitor

SPHERES

Small

Co3 O4 /nitrogen-doped carbon hollow spheres (Co3 O4 /NHCSs) with hierarchical structures are synthesized by virtue of a hydrothermal method and subsequent calcination treatment. NHCSs, as a hard template, can aid the generation of Co3 O4 nanosheets on its surface; while SiO2 spheres, as a sacrificed-template, can be dissolved in the process. The prepared Co3 O4 /NHCS composites are investigated as the electrode active material. This composite exhibits an enhanced performance than Co3 O4 itself. A higher specific capacitance of 581 F g-1 at 1 A g-1 and a higher rate performance of 91.6% retention at 20 A g-1 are achieved, better than Co3 O4 nanorods (318 F g-1 at 1 A g-1 and 67.1% retention at 20 A g-1 ). In addition, the composite is employed as a positive electrode to fabricate an asymmetric supercapacitor. The device can deliver a high energy density of 34.5 Wh kg-1 at the power density of 753 W kg-1 and display a desirable cycling stability. All of these attractive results make the unique hierarchical Co3 O4 /NHCS core-shell structure a promising electrode material for high-performance supercapacitors.

Core–Shell Nitrogen‐Doped Carbon Hollow Spheres/Co<sub>3</sub>O<sub>4</sub> Nanosheets as Advanced Electrode for High‐Performance Supercapacitor

Core–Shell Nitrogen‐Doped Carbon Hollow Spheres/Co3O4 Nanosheets as Advanced Electrode for High‐Performance Supercapacitor

Core–Shell Nitrogen‐Doped Carbon Hollow Spheres/Co₃O₄ Nanosheets as Advanced Electrode for High‐Performance Supercapacitor