N-doped TiO2 hierarchical microspheres as electrode for high-performance supercapacitors

•N-doped TiO2 microsphere was prepared by hydrothermal process for supercapacitor.•Structural design of sphere can provide large surface area and suitable pore size.•Nitrogen doping can improve the electrical properties of TiO2 electrode.•The specific capacitance increases from 2.26 to 11.89 mF/cm2 at 1 mA/cm2.•The capacitance remains 90.5% of the original capacity after 10,000 cycles.