Scalable and controllable synthesis of multi-shell hollow carbon microspheres for high-performance supercapacitors

It is a great challenge to enhance the specific capacitance while without sacrificing the remarkable rate capability and long-term cycle durability of carbon materials for supercapacitors. Here we present a novel spherical and multi-shell hollow carbon material with tunable shell numbers and N-doping derived from a sequential synthetic route recombining hydrothermal nucleation, carbonization, and etching. The very special features, including uniform in shape and size, hollow structure, core/multi-shell architecture, hierarchical porous structures, and nitrogen doping, facilitated high specific surface area, abundant active sites, fast ion diffusions kinetics and good electrical conductivity. As a result, very superior electrochemical performance with an excellent combination of high specific capacitance (318.5 F g−1), and outstanding rate capability (the capacity retention ratio was more than 80% when the current density was raised from 0.1 to 10 A g−1), and very stable cycling (more than 94% capacity retention after 50000 cycles at 1 A g−1) has been achieved. This hierarchical multi-shell strategy opens a new avenue for design of high performance electrode for next-generation energy storage devices.